Journal of Environmental Engineering (Transactions of AIJ)
Online ISSN : 1881-817X
Print ISSN : 1348-0685
ISSN-L : 1348-0685
Volume 85 , Issue 777
Showing 1-11 articles out of 11 articles from the selected issue
    Yoshito YAMAZOE, Takeyoshi UEMATSU, Yuhei KOYAMA, Shintaro FUKUDA, Yut ...
    2020 Volume 85 Issue 777 Pages 779-789
    Published: 2020
    Released: November 30, 2020

     Traffic vibration causes problems from a viewpoint of habitability occasionally. The characteristic of traffic vibration is non-stationary vibration whose amplitude and frequency change with time. It has been clarified that non-stationary vibration can be evaluated by considering the duration time of the vibration in addition to the amplitude and frequency by previous study. Another characteristic of traffic vibration is multi-axis vibration in which vibration in multiple directions are combined. However, there are few studies on evaluation methods for multi-axis vibration. The aim of our study is to establish an evaluation method for horizontal and vertical dual-axis traffic vibration.

     In this study, we conducted sensory evaluation test using the shaking table which can vibrate simultaneous horizontal and vertical dual-axis, and examined the relationship between human sensation for the vibration and acceleration measured on shaking table.

     The investigated procedure is described as follows;

     1) 18 traffic vibration waveforms measured at the upper floor of a wooden house near a road or railroad were selected.

     2)The sensory evaluation test was conducted. At the sensory tests, the panels were made to experience sample vibration on the shaking table and answer how they felt it. The sample vibrations are 72 lateral and vertical dual-axis vibrations and 72 fore-and-aft and vertical dual-axis vibrations which are made by changing the amplitude each of waveforms selected 1) to 4 levels.

     3)From the panels answer, we constructed psychological scales of feelings of amplitude, annoyance and discomfort against various vibrations using a method of successive categories.

     4)We calculated several kinds of performance value candidates which were supposed to correspond to human sense and examined the correspondence with the psychological scales.

     In this study, we revealed that the performance values C(1/√2:1:1)VLT(630ms, 60dB) applicable to the evaluation of horizontal and vertical dual-axis vibration. C(1/√2:1:1)VLT(630ms, 60dB) is a value that takes into account the maximum value of the level value obtained by converting the combining acceleration to a level value and the total time which the level value is 60dB or more. Where, the combining acceleration is the value obtained by combining the RMS acceleration values in each direction. When combining, multiply the RMS acceleration value in the lateral direction by 1/√2, taking into account the fact that the human sense of vibration in the lateral direction is insensitive. The method of calculating from the maximum value of the level value and the duration time is the same method as the performance value of vertical vibration, horizontal uniaxial vibration and horizontal dual-axis vibration presented in previous research. In this study, we clarified the combining ratio in tri-axis even although it targeted horizontal and vertical dual-axis vibration, it appears to be important knowledge for performance value of tri-axis vibration.

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  • Yuhei KOYAMA, Yoshinori OHASHI, Shintaro FUKUDA, Yutaka YOKOYAMA
    2020 Volume 85 Issue 777 Pages 791-801
    Published: 2020
    Released: November 30, 2020

     Walking vibration can cause complaints to building users on building floor, especially on timber floor. However, the estimation method of walking vibration at the design stage is still not established. In the previous study, the vibration characteristics of a CLT floor subjected to walking vibrations was measured. Then, the finite element model was also created to investigate the influence of varying material properties and boundary conditions on the vibration performance of the floor. Furthermore, via measurement three specimens of CLT floor, the influence of CLT floor-wall connection upon vibration characteristics was investigated. Finally, through analytical modeling based on these results, the span table of CLT floor from the viewpoint of walking vibration was presented.

     In this study, continuing from the previous study, to reveal the influence of finishing joist floor on CLT floor on walking vibration, CLT floors made of two kinds of materials with finishing joist floor were investigated. At first, vibration characteristics of the CLT floors without joist floor and with joist floor subjected to walking vibration were measured. Then, via some investigation about parameters, element shapes, and walking excitation force, four finite element models were also created and the analysis methods to reproduce the measured results were obtained.

     The investigation procedure and result are described as follows;

     1) Vibration characteristics of two CLT floors (one is made of KARAMATSU, the other is made of TODOMATSU) without joist floor were measured through static loading test, dynamic impact test and walking vibration test. It was found that the stress was transmitted not only in the strong axis direction but also in the weak axis direction regardless the half lapped joints, as in the previous study.

     2) Vibration characteristics of two CLT floors with joist floor were measured through dynamic impact test and walking vibration test. Comparing to the results measured without joist floor, it was found that the natural frequency was increased by the finishing joist floor despite of the floor weight increase. And the damping ratio was slightly increased by the finishing joist floor. Furthermore, the VLT index decreased by 8dB, and the evaluation of the walking vibration on the annoyance scale was improved in two categories by the finishing joist floor.

     3) In the final analysis models which can reproduce the measured results, the half lapped joint was set as lower vertical gap, the elements on the floor with no vertical support were set as loading their weights at the point. In addition, the finishing joist floor was set as the elements of the same size, shape, and material properties.

     4) The walking vibrations on these floors were reproduced by the analysis method which was presented in the previous study.

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  • Yoko IKEGAMI, Youko INOUE
    2020 Volume 85 Issue 777 Pages 803-810
    Published: 2020
    Released: November 30, 2020

     The co-use of daylight and artificial lighting is important from the perspective of reducing energy consumption. However, as the illuminance in a room frequently changes when only using daylight, this may cause habitants to feel inconvenience when carrying out daily activities. In this report, we implemented a questionnaire on daylight fluctuations in rooms, actual measurement of the daylight fluctuations, and an impression evaluation under the environment where illuminance change, to investigate the necessity of illuminance control for temporary fluctuations in daylight in rooms.

     From the questionnaire results, it is considered that many people want to actively use daylighting, and are, in fact, using it, but a large majority of them have felt discomfort regarding the fluctuations and brightness in daylight. 74% of people have noticed daylight fluctuations, and 40% of them have felt discomfort with daylight being too bright and in regard to fluctuations in illumination. In addition, some people feel discomfort with automatic dimming of artificial illumination.

     Measurement of daylight illuminance was conducted for 8 days on August and September 2014. Global illuminance, illuminance from unobstructed sky, and horizontal illuminance in a room were measured for 1-second intervals. The cumulative relative appearance frequency of illuminance change ratio from 0.83 to 1.20 is 88.9%, and that 0.67 or less or 1.50 or greater is 2.3%. The illuminance change continuation time at 80 minutes or longer exists, however cases at 2 seconds or shorter share 32.9 %.

     We grasp the ratio of discomfort in relation to temporal illuminance changes in a room where the light environment only monotonically increases or decreases using the subject of an experiment. In such space, we implement the illuminance change ratio by 0.71 or less or 1.41 or greater, which deems to be a comparatively large change for daylight fluctuation. The larger the illuminance change ratio increases, the greater the ratio of discomfort increases, as the change continuation time increases, the lower the discomfort ratio decreases. Additionally, when the illuminance level increases, if the illuminance level is high before the change, the discomfort ratio is high, whereas if the illuminance decreases and the illuminance level were high before the change, the discomfort ratio is low. The discomfort ratio in regard to temporal illuminance fluctuations with a change continuation time of 8 seconds and illumination change ratio of 2 times or 0.50 times was 5.3-58%. Most of these figures are lower than the questionnaire results about cases in which discomfort was felt with the fluctuation.

     From these a questionnaire, actual measurement, and an impression evaluation, it was shown that as even if the appearance ratio is low, discomfort occurs in relation to comparatively large daylight fluctuations, controlling to mitigate fluctuations in the illuminance due to daylight may contribute to the quality of the lighted space. Further, we will clarify, how workability and atmosphere are evaluated when illuminance changes in addition to discomfort concerning temporal illuminance change. Furthermore, assuming cases when illuminance is supplemented with artificial lighting to maintain fixed level of illuminance on a desk by daylighting, we will clarify the impression of a room when adjusting the illuminance using artificial lighting.

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  • Naoki KAGI, Kenichi AZUMA, Hoon KIM, U YANAGI, Kenichi HASEGAWA
    2020 Volume 85 Issue 777 Pages 811-817
    Published: 2020
    Released: November 30, 2020

     The emission mechanisms for 2-ethyl-1-hexanol (2E1H) are not only the primary emission that directly generates from materials but also the secondary emission from material that contains di (2-ethylhexyl) phthalate (DEHP) in PVC floor using with various adhesives and self-leveling sub-floor material that contains water with high pH. Many previous studies showed that the secondary emission for 2E1H is the main emission source in the indoor environments that use concreate and PVC flooring materials. However, there are some cases where the 2E1H concentration are high even in a room that is not constructed with concrete and PVC flooring materials.

     This study carried out the field measurements of airborne 2E1H and the 2E1H emission tests for PVC sheets, carpets and adhesives on various humidity conditions by using the small chamber method for focusing on the emission behavior of 2E1H due to moisture supplied to flooring materials from the air and base material. The airborne 2E1H with humidifiers in the room and wiping of the materials were also measured to investigate the characteristics of indoor concentration.

     From the results of the field measurements, 2E1H was detected in all office rooms in this study, and the 2E1H concentrations of the room B and H were higher than 130 µg/m3. Since the high concentration of 2E1H was detected even in the room where no PVC flooring material was directly applied to the concrete, the primary emission also contributed to the increase of the indoor 2E1H concentration.

     From the emission test from the PVC sheet, tile carpet, adhesives and composite material on the various water conditions, it was confirmed that the 2E1H emission rates for PVC sheet and adhesive were increased due to the moisture from the base material and the water vapor in the air. It was found that moisture of the materials and humidification in the air increased the primary emission of 2E1H from building materials.

     From real-scale experiments, it was shown that 2E1H emissions from PVC building materials increased due to humidification and increased water content of building materials. The water content of the building material and 2E1H emission did not change even if the materials were wiping for adding water.

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  • Sung-ki SONG
    2020 Volume 85 Issue 777 Pages 819-826
    Published: 2020
    Released: November 30, 2020

     In this study, in order to spread and promote rainwater harvesting and to realize Zero Water building, the actual water use situation for eight years in a university lecture building with a rainwater harvesting system of 35.4 mm water stock capacity was clarified, and the performance of rainwater harvesting and the possibility of achieving Zero Water were investigated. The following findings were made.

    I. The situation of Water Using and the Performance of Rainwater Harvesting

     1) Annual water usage of the lecture building ranged from 16,700 m3 to 22,000 m3, with an average of 19,400 m3, and trended upward through 2017 as the rainwater harvesting system water usage increased. The raw water was about 20% rainwater and 40% each of both tap water and well water, and the rainwater harvesting system was almost entirely funded by about 30% rainwater and 70% well water.

     2) The rainwater utilization rate and rainwater replacement rate of the rainwater harvesting system were 71% and 33% respectively.

     3) The evapotranspiration on lecture building site was about 20% of the annual precipitation, which was about 13% less than on natural site. The total of evapotranspiration and infiltration was about 34%, which is about 33% less than the recommendation of the Architectural Institute of Japan "Technical Standard for Rainwater Harvesting ". As the installed rainwater harvesting system in the lecture building, about 30% of the annual precipitation was controlled by outflow.

     4) The average annual water charges of the lecture building without sewerage charges for cooling tower water were 9,600,000 yen, and the percentage of tap water and sewerage charges was 66% and 34%, respectively. As the installed rainwater harvesting system, the water charges was reduced about 41% and the initial cost recovery by the reduced water charges was about 9.5 years.

     5) The Zero Water achievement rate of the lecture building was about 53%.

    II. The Possibility of Zero Water

     1) When the use of raw water in the rainwater harvesting system was extended to drinking, the Zero Water achievement rate was about 80%, the rainwater utilization rate and rainwater replacement rate was improved to about 90% and 40% respectively, the rainwater outflow control effect and CO2 emission reduction both was increased by 10% compared to the current using, and the initial cost recovery was reduced to 8.7 years.

     2) When the use of raw water in the rainwater harvesting system was expanded to drinking and the rainwater collection area was increased more than 1.15 times, Zero Water was achieved, and the rainwater replacement rate was increased to 42-44%, and the rainwater outflow control effect was increased 13-17% more than the current use. However, it was estimated that increasing the collection area by more than 1.15 times will not reduce water charges by much and will not shorten the recovery period for initial costs.

     3) In the future, it will necessary to consider the possibilities of Zero Water including introduction of green infrastructure and capacity of storage tank and water conservation.

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  • Shohei MIYATA, Yasuhiro KUWAHARA, Jongyeon LIM, Yasunori AKASHI, Naoki ...
    2020 Volume 85 Issue 777 Pages 827-835
    Published: 2020
    Released: November 30, 2020

     To reduce carbon dioxide (CO2) emissions, interest in renewable energy, such as solar and wind power, is gradually growing. However, there is an imbalance between the supply and demand of such electric powers. Demand Response (DR) has been the subject of many research and demonstrations as a control measure aimed at power load leveling. In this study, we propose a carbon activated demand response (CADR) that considers a dynamic CO2 emission factor that is estimated hourly. We investigate the control methods used to minimize carbon emissions from the central cooling plant which has two centrifugal chillers. Based on the estimated dynamic CO2 emission factor that fluctuates every hour, the operation of the chillers with water heat storage tanks as an energy buffer was optimized. The novelty of this study lies in the proposition of the dynamic CO2 emission factor and the quantification of the low-carbon effect when the cooling plant with water heat storage tank is optimally controlled based on the dynamic CO2 emission factor.

     The CO2 emission factor is defined as the ratio of the amount of CO2 emitted from power generation by the amount of power generation [kg- CO2 / kWh]. Since data on hourly power generation was available, we used the hourly emission factor for estimating the dynamic CO2 emission factor in our study.

     The cooling plant of a large office building, with a water heat storage tank (total 6,704 m3) and three refrigerators (total 2,470 Rt), was the subject in this study. The control behavior of the cooling plant was simulated to investigate low carbon control. Conventional control starts heat storage at 22:00 or 8:00 and releases heat according to the load. In contrast, the proposed CADR uses Model Predictive Control (MPC) that optimizes the operation of the chillers every two hours. Based on the dynamic CO2 emission factor and the power consumption predicted by the simulation, the combination of the start and stop of the chillers that minimizes the CO2 emissions for the next 48 hours is calculated. Since load prediction is required for power consumption prediction, cases where load prediction has errors, were also included. In this study, we compared the performance of CADR with the conventional method for one week, from 0:00 of June 4, 2017, to 23:59 of June 10.

     The results show that the CADR was able to reduce CO2 emissions by 46.77% and 12.89% compared to the conventional method that starts heat storage at 22:00 and 8:00, respectively. In conventional control, the heat is regularly stored and full at the end of heat storage, but in CADR, heat is stored when the emission factor is low. In addition, this method was effective in reducing CO2 emissions, even with a load prediction error of 10%. The future research focus will be to calibrate the equipment model for MPC, expand the type of energy buffer such as batteries, and analyze the contribution of the proposed method to the power systems.

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  • Chenghao WEI, Miwako FUJITA, Daisuke NARUMI
    2020 Volume 85 Issue 777 Pages 837-847
    Published: 2020
    Released: November 30, 2020

     Supermarkets and grocery stores represent an important energy-intensive role in the commercial sector. In Japan, grocery stores occupy 8% of energy consumption in the commercial sector. Refrigerated and frozen display cases are widely used in grocery stores and those occupation of energy consumption in a store range from 50% to 67%. In addition, plenty of research illustrated that alterations in humidity and temperature affect the cooling load of display cases. Also, cold air leaking from display cases can influence the cooling and heating load of space conditioners because of affecting room temperature. Furthermore, the cold leakage air does harm to the thermal comfort of stores. Hence, it is essential to explore the interaction between space conditioners and display cases while analyzing energy consumption characteristics and thermal comfort in stores

     Although some energy calculation software or methods such as Energy Plus have been used to simulate the energy consumption of space conditioners and display cases in stores in terms of indoor temperature, regarding a store as a temperature completely mixing space leads to a lack of accuracy for the reason of uneven temperature distribution in grocery stores. For the same reason, it is difficult to evaluate the thermal comfort of grocery stores without mastering the temperature distribution. Thus, hardly were energy-saving strategies evaluated in terms of both energy-saving potential and thermal comfort simultaneously.

     In this study, focusing on space conditioners and display cases in grocery stores, CFD (Computer Fluid Dynamics), was utilized to try to build a method that can evaluate energy-saving strategies by mastering the indoor temperature distribution influenced by display cases and space conditions.

     In the first report, based on a series of experimental results, 5 kinds of display case CFD models were built to imitate their cooling load and low-temperature leakage air in different temperatures or humidity environments. The results of this report are shown below.

     (1) Detailed display case CFD models, in which even mock goods in display cases were reproduced, were built based on a series of experiments performed in a laboratory with constant temperature and humidity. And the positive reliability, satisfying the purpose of this study, of them was confirmed.

     (2) According to the results obtained from detailed display case CFD models, especially the cooling load of refrigerated display cases can be influenced easily by altering indoor temperature or humidity.

     (3) Simplified display case CFD models were built to decrease the computation load while setting them in a large space, for example, a store. Only leakage and influx surface were set in the front of a cube, and the relations between the temperature of influx air and boundary values of these surfaces were obtained from the results of detailed models.

     (4) In spite of some bias, the simplified models were able to reproduce the detailed models properly in terms of the temperature space distribution. And the calculation load of computers can be reduced by 44% when replacing a kind of display case detailed model in a large space by the corresponding simplified model.

     Above all, by employing the simplified CFD models for building grocery store CFD models, it is possible to evaluate kinds of energy-saving strategies adopted in grocery stores in terms of indoor thermal comfort and energy consumption, for example, altering space conditioners temperature, altering the numbers or types of display cases, and etc.

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  • Keizo YOKOYAMA
    2020 Volume 85 Issue 777 Pages 849-857
    Published: 2020
    Released: November 30, 2020

     In this study, the intensities of resource consumption were calculated as a database for evaluating resource consumption in the building industry based on the 2011 Input-Output Table for Japan. The following conclusions were drawn:

     1) The intensities of resource consumption were calculated to determine "input of natural resources etc. by equivalent conversion of primary resources (RMI: Raw Material Input)”, considering the overseas extension effects of manufacturing imported resources and products. These intensities included 11 resources and 393 industrial sectors and were indicated per consumer price in units of one million yen.

     2) The coefficients of raw material equivalent (RME) for obtaining RMI was based on EUROSAT data.

     3) The RMI associated with Japanese construction in 2011 accounted for 13.0% of the RMI of all industries and 43.6% of that of the entire construction sector including civil engineering.

     4) The resource consumption per floor area of the entire building was 1,355 kg/m2 on an RMI basis and 1,019 kg/m2 on a direct material input (DMI) basis, and the overseas extension effect was estimated to be about 33%.

     5) The RMI of metal resources was 2 to 40 times larger than the DMI because of metal resources were imported. In contrast, the majority of soil and stone resources were not imported, and hence, the difference between RMI and DMI was small. In addition, energy resources were predominantly imported, so the difference was large about 1.3 to 2.1 times. For biological resources, the difference was 1.5 times larger for wood, owing to the import of wood products.

     6) In terms of building structure, non-wooden buildings consumed large amounts of soil and stone resources and metal resources because concrete, steel bars and steel frames were used. In contrast, wood-based construction consumed more wood than non-wood-based construction.

     7) “Resource productivity by industrial sector” for the four construction sectors was calculated. The resource productivity of overall construction was about 56, 000 yen/t, significantly less than the overall 387,800 yen/t for all sectors in Japan. Residential construction (wooden) sector had the highest resource productivity, followed by the non-residential (wooden) sector and the non-residential (non-wooden) sector.

     8) Resource productivity by industrial sector is meaningless when compared with other industries, and is suitable for comparing trends in the same sector. It is an effective index for evaluating trends in the building sector.

     9) In the future, resource productivity in the building industry will be calculated using resource productivity in terms of “RMI (primary resource equivalent equivalent)” as an evaluation index, and calculating intensities of resource consumption for other ages. In addition, we would like to evaluate the resource productivity of individual buildings and consider measures to construct buildings with high resource productivity.

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  • Masato MIYATA, Susumu HIRAKAWA
    2020 Volume 85 Issue 777 Pages 859-869
    Published: 2020
    Released: November 30, 2020

     In order to achieve further energy savings in buildings, it is essential to accurately clarify the actual situation between energy saving performance and building envelope and equipment design specification followed by taking effective policy measures. In previous surveys, highly reliable information on energy consumption has been collected through the use of detailed statements of utility bills, but in most cases only an overview of the building envelope and equipment design specifications has been interviewed due to the high level of expertise required of the respondents. Therefore, the details of the design specifications are unclear.

     The purpose of this research is to analyze the input/output data from the calculation program to confirm compliance with building energy code and to find out the standard design specifications of building envelope and equipment for commercial buildings. Since commercial buildings of 300 m2 or more are obliged to report the evaluation results of the building energy code, all commercial buildings of 300 m2 or more can be surveyed.

     This paper focuses on office buildings built in the financial year of 2018. A total of 1731 buildings were analyzed in this report. These buildings have been assessed for the building energy code by the Model Building Method (a simple evaluation method) and do not have a mix of building uses other than offices. The findings are presented below.

     ・ Analysis of the distribution of BEIm, which is a performance evaluation index for the building energy code, showed a difference in the number of buildings between BEIm = 0.55, 0.65, and 0.85. Therefore, in this report, standard design specifications were found in five groups: Group I (BEIm<0.55, 3.4% of the total), Group II (0.55 ≦BEIm<0.65, 17.0% of the total), Group III (0.65≦BEIm<0.85, 61.9% of the total), Group IV (0.85≦BEIm<1.00, 16.6% of the total), and Group V (1.00≦BEIm, 1.1% of the total).

     ・ The relationship between BEIm/AC, a performance evaluation index of air-conditioning equipment, BEIm/L, a performance evaluation index of lighting equipment and with or without the adoption of photovoltaic power generation, was compared for each group, and it was found that there were differences in these relationships for each group. As a result, it was determined that the energy performance of the office building can be roughly explained by the specifications of the envelope, air conditioning, lighting, and photovoltaic equipment.

     ・ The distribution of design specifications for envelope, air conditioning, lighting and photovoltaic equipment was compared for each group, and it was shown that there were clear differences between groups in terms of coefficient of heat transmission of exterior wall and roof, window area rate, rated capacity and rated efficiency of air conditioning heat source equipment, power consumption of lighting equipment and power generation capacity of photovoltaic equipment.

     Based on the results of the above analysis, this paper identifies the standard design specifications for office buildings as of FY 2018 according to the evaluation result of the building energy code.

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  • Influence of total heat exchange type whole-house air-conditioning ventilation system
    Akemi IWAKI, Takashi AKIMOTO, Takuya FURUHASHI
    2020 Volume 85 Issue 777 Pages 871-880
    Published: 2020
    Released: November 30, 2020

     It is common to use an air conditioner as a summer sleep measure to improve the quality of sleep; when using an air conditioner at night, however, having an air conditioning control that does not affect people is necessary as concerns about adverse effects on one’s physical conditions exist. The purpose of this study is to investigate the thermal environment that can influence satisfactory sleep and to create a comfortable sleep environment. We compared individual air- conditioning (room air-conditioning), which allows for rapid temperature changes as well as entire-room air conditioning, using a total heat exchange ventilation system, and investigated their effects on sleep.

     In this study, we conducted an experiment in a whole-house air-conditioned model house in Tokyo in the summer. As previous studies have not shown the effect of whole-building air conditioning control on sleep, we conducted a subject experiment with the aim of grasping the indoor environmental conditions at bedtime so as not to cause thermal discomfort to the human body while improving its sleep. Using the entire building air-conditioning model house, which is compliant with the 2016 energy saving standard, the relationship between the thermal air flow control during sleep and the psychological as well as physiological state of the subject was clarified. As an air conditioning comparison, individual air-conditioning (room air-conditioning) was used a condition. The participants were six young men in their twenties, four of whom were used in the analysis.

     As a result, the quality of sleep (δ power) was improved by the whole-house air-conditioning, which was controlled in a step-by-step manner. In contrast, sleep latencies were affected by sudden temperature changes. Therefore, it can be reasonably stated that to control the temperature gently without causing a sudden temperature drop at the time of falling asleep creates a comfortable sleep environment.

     In addition, as a significant relationship between subjective evaluation and the measured values was recognized, the temperature setting performed in this experiment is considered suitable for a sleep environment.

     As other physiological quantities, such as heart rate, decrease with deepening sleep, the parasympathetic nerves predominate and tension is relaxed; thus, it is presumed that this is closely related to the δ power. In the future, it is predicted that the use of air conditioning that automatically controls temperature over time will progress.

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  • Hideyo TSUKAZAKI, Satoshi KATAHIRA, Masahiro YOKOYAMA, Hideyuki MAEKAW ...
    2020 Volume 85 Issue 777 Pages 881-889
    Published: 2020
    Released: November 30, 2020

     In this paper, we proposed teaching materials to quickly acquire carpenter skills. The contents of these teaching materials are focused on a drawing method called Kikujutsu (Roof framing geometry). In Japan, there is a problem that there are few young people who want to become a carpenter. As the number of young carpenters is diminishing, carpenter's skills need to be inherited smoothly from experts to beginners. Therefore, it is necessary to make the beginners acquire carpenter skills in a short time.

      Conventionally, net drawing teaching materials were used to learn roof framing geometry. However, the net drawing method needs a long learning period. Because it deals with three-dimensional things in two dimensions, high space grasp ability is required. Therefore, in this study, the teaching materials of roof framing geometry were developed with the drawing made by 3D-CAD and the model made by 3D-printer so that the members of 3D space could be understood visually.

     Moreover, in order to clarify the effectiveness of proposed teaching materials, the results of the training were verified for 44 students majoring in architecture. At first, 44 students were divided into two groups. One is T group, and the other is M group. T group learned roof framing geometry using the net drawing teaching materials. On the other hand, M group used the 3D-model teaching materials. Confirmation tests were conducted on these two groups after class. As a result of the confirmation test, it was found that the teaching materials using the 3D-model had a large educational effect.

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