We conducted a study of entry tasks to examine the characteristics of the task at night. We surveyed the amount of entry tasking (total character count), typo rate and brain waves both in the daytime and at night. As a result, the amount of entry tasking and the typo rate are greater at night then in the daytime, and further, at night the alpha wave was controlled and the beta wave was increased compared to the daytime.
Through this study, we found out that the amount of entry tasking is increased while the quality was decreased at night. In addition, we found out that the night time operation was processed in the excited state of mind, controls the decrease of the activity level in the brain and cause an excessive strain of bodily function.

View full abstract

In Japan, aging is rapidly progressing, and the number of patients of senile cataract is steadily increasing. This fact has not only become a medical subject but also a large social problem. Fraction of cataract people has reportedly been near 60% for ages of the 50's and beyond 90% for the 80's or higher, so it may be said that countermeasure against this sort of visual impairment is also one of extremely important subjects in order to raise life quality of the elderly. In this experiment, the authors attempted study and speculation with respect to the manner of viewing colors on the multicolored LED lighting display board by means of goggle that fictionally reproduce visual environment of the cataract. It became evident from the result that perception of color has a large difference from yellowish green to aqua between visual environments of the cataract and normal, and further we qualitatively revealed its range and difference, too.

View full abstract

In recent years, with the utilization of blue Light Emitting Diode, the Light Emitting Diode element is beginning to be actively used in various scenes, and Light Emitting Diode is used even for traffic light now. The Light Emitting Diode traffic signal light has little power consumption as compared with the traffic signal light using the conventional electric bulb, and spreads to progress increasingly from now on. Because the discernment of the yellow of a signal light and red is difficult for sense-of-color unusual person, in the present signal light system, yellow signal light color is made somewhat brighter than red signal light. The aim of the present study is to collect the fundamental data for the display of the traffic signal light, which is easy to be recognized also by sense-of-color unusual persons. The results revealed that the optimal brightness of the yellow light from which a sense-of-color unusual person can distinguish the difference between yellow and red, i. e., “vision barrier-free domain”, is the area where yellow light is 2.8 times brightness of the red light.

View full abstract

In recent years, various computer input devices have been developed with technological advances. A touch pen becomes more popular as a wireless input device for computers, PDAs and mobile phones. Although previous studies on a touch pen mainly focused on its physical characteristics, hand posture, and movement velocity, user input area has been rarely studied. Unlike tablets or pads with their size fixed, a wireless touch pen must set up its size of input area appropriately under normal circumstance or working environments. This study aims to identify the effect of the size of user input area on task performance of a touch pen. In addition to the size of user input area, display size and control-to-response ratio were examined through the experiment where eighteen subjects participated voluntarily. Task completion time, error rates and subject preference as performance measures were obtained from writing and drawing tasks. Through the experiment, appropriate size of user input area was found with respect to display size and control-response ratio. The study is expected to help the designer determine the specification of a touch pen as an input device for digital devices.

View full abstract

The purpose of this study was to understand the customer's needs and to construct house of quality (HOQ) for shoes using the customer's needs and quality function deployment (QFD). The customer's needs was measured by a questionnaire and analyzed by the structural equation model (SEM). The engineering characteristics of HOQ was analyzed by the analytic hierarchy process (AHP). The results of this study showed that the HOQ for shoes was effected by the customer's needs.

View full abstract

Studying the evolution of Korea's stewardess uniform, one finds that there has been no drastic alteration in the shape, though there has been for instance more or less emphasis on the shoulders' design (eventual addition of pads, and their shapes). Differences can also be found in the length of the jacket. The design and colors of the blouse showed some variations, but per se accessories play of course a role for the commercial image as it does for many airlines: scarf, gloves, hairpin, personal name badge, company logo badge, even shoes. Costume design reflects almost always contemporary social and cultural backgrounds. This applies also to a certain degree to flight attendants costumes, but it must be noted that airways uniform design comes usually more in line with the international fashion trends than with domestic cultural elements (with the important exception of some accessories). Here we see that costumes of korean and japan airways companies indeed follow mainly the international trend while adding minor but visible cultural design elements. Another aspect of costumes design which we look at here concerns sizing, which has somewhat evolved in Korea along with the change of the body size of the general population of that country. Finally we give our view on the idea that fashion repeats often itself, at least partly, trying to foresee what may come ahead in the domain of stewardess clothing fashion design.

View full abstract

Human factors engineering has been taught in the design fields and considered as a necessary course for design students. We, ergonomists working with a design department, analyzed the current status of ergonomics curricula in the Korean design colleges. Sixty one percent of schools with design departments were offering ergonomics courses and most courses were electives. Comparatively more ergonomic courses were offered in industrial design and digital media departments. Ergonomic and human factors knowledge might not properly be acquired with this current status of the design curricula and systematic solutions should be considered and prepared for the future Korean designers.

View full abstract

A lot of physiological parameters, mainly cardiovascular indexes, were obtained from fifteen male participants. They were asked to perform a 5-minute multi-task (MATB: Multi-Attribute Task Battery) for three times. The MATB consisted of four tasks, i. e., compensatory tracking task, system monitoring task, resource management task and communication task. The communication task was not operating in this experiment. Two participants out of fifteen showed bradycardia during the performance of MATB comparing with before and after resting periods. However, many of other participants did not show clear heart rate decreases. Therefore, above-mentioned two participants should be grouped as Vascular Reactors who show dominant Total Peripheral Resistance increment (and heart rate decrements consequently) to mental challenge rather than Cardiac Reactors who show increments in Cardiac Output. In vascular Reactors, increased vagal tone (parasympathetic nervous system activity) is elicited by mental tasks. Therefore, when we evaluate the mental workload using autonomic nervous system measures, we may be confused by the results obtained if there are Vascular Reactors, Cardiac Reactors and Mixed Reactors in participants' group at the same time.

View full abstract

To exercise with a bicycle ergometer safely and effectively, anaerobic threshold is a useful indicator of cardiopulmonary exercise test. In this study, AT was estimated with heart rate variability. Electrocariogram (ECG) was measured with palm electrodes mounted on handlebars of a bicycle. The palm lead ECG us heavily contaminated with Electromyogram (EMG) noise. The first step of our study was to eliminate the noise and to find R-R intervals of the ECG. The second step was to control the load of the bicycle ergometer to maintain the exercise at AT level, by maintaining Mean of Squares of Successive Difference of Heart Beat (MSSD) at 25ms2.

View full abstract

Lately, various shoes pursued biomechanical functions have developed. For the gate purpose, shoes that can keep the balance of body and activate whole body muscles are developed. Among these developing shoes, shoes having the variation of toe & heel spring are developed. Then, this study investigates the effect due to the variation of toe and heel spring by EMG analysis. Shoes are selected by 3 kinds (A, B and C) of following types: A type has 0.5-0.7cm toe and 0cm heel spring, B type has 1.5-2.0cm toe and 0.5-1.0cm heel spring and C type has 4.5-5.0cm toe and 2.5-3.0cm heel spring. Measurement parts are calf (gastrocnemius muscle), thigh (nastus muscles), and waist (erector spinae muscles).
Results showed, the shoes having a large variation of toe and heel spring has a large IEMG. And thigh (nastus muscles) showed statistical significance, however the other parts has no significant effects. During gate, the change of mean frequency was founded on same measurement points according to the change of toe, heel spring and types of shoes. So, we can foresee the correlation between the variation of spring of shoes and the CBM (Center of Body Motion). As a future study, measurement of CBM by the motion analysis according to the change of toe and heel spring could be followed.

View full abstract

Several studies have been made on that the power of the high frequency components (HF) from 0.15 to 0.40Hz in heart rate reflects the parasympathetic nerves activity. However, there are some problems to apply HF to the evaluation index. For example, conversion from the time domain data into the frequency domain data needs complicated calculation. The purpose of this study is to show the evaluation method by Lorenz plot (LP) at electrocardiogram (ECG) RR intervals as a new evaluation index of the parasympathetic nerves activity. All the data of LP is projected on y=x axis and y=-x axis. In y=x axis, standard deviation σ(x) of the distance from the coordinate origin is calculated. In the same way, in y=-x axis, standard deviation σ(-x) is calculated. Ellipse area S showing variation of LP is S=π×σ(x)×σ(-x). The correlationship of the significance probability 1% is shown between HF and LP's ellipse area S at ECG RR intervals. This indicates that LP's ellipse area S at ECG RR intervals is a reliable evaluation technique that takes the place of HF.

View full abstract

The aim of this study examine the difference caused by relaxation resulting from a breathing exercise in healthy females during menstrual cycle as measured by power spectral analysis of heart rate variability (HRV). The subjects were 15 women, aged 21-39 years. The effect of the breathing exercise was measured in terms of HRV before and after a mental task, in both follicular and luteal phases. The results showed that the high-frequency (HF) was increased significantly by the breathing exercise, and the LF/HF ratio was not changed significantly in follicular phase. These results indicated that the parasympathetic nervous system activity was increased. On the other hand, HF was not changed significantly by the breathing exercise in luteal phase. Moreover, the LF/HF ratio increased significantly. These results indicated that tension of the sympathetic nervous system was continuous. Therefore, the effect of the relaxation was exhibited in follicular phase, and not in luteal phases. It will be necessary to consider other effective methods including continuous breathing exercise for the relaxation in luteal phase.

View full abstract

This study was performed to estimate the prevalence rate of VWF (vibration white finger) under different work posture while operating a light-weighted powered hand grinder. For the experiment, 8 different types of wrist posture (natural, unlar-flexion, radual-flexion, flexion, extension, complex posture, and etc.) and 3 types of feed force (20 [N], 50 [N], 70 [N]) were considered. 10 male subjects were employed to polish metal plate with an 8-inch hand grinder. All of them were normal and healthy with no history and symptom of the work related musculoskeletal disorders in the dominant hand. Vibration acceleration data were recorded with sampling rate 2048 [Hz]. In addition, weighted R. M. S. accelerations at the tool were used to estimate factors from the recorded tri-axial vibration acceleration. The results indicate that controlled and free posture were lower hand other work posture, and as feed forces becomes larger the prevalence rate decreased.

View full abstract

The aim of this study was to evaluate working conditions using multi display VDTs in terms of work performance, head movement and EMG activities of the neck. A comparative study using single, multi and large display type VDT workstations, was undertaken to obtain ergonomic data applicable to the guidelines and recommendation for VDT operations using multi displays. Subjects comprised 10 healthy volunteers who performed data search and entry tasks for 5min on each workstation. Work efficiency of the single display was inferior compared to multi and large displays. Head movement was greater with multi and large displays than with a single display. EMG activities did not differ significantly between multi and large displays.
The characteristics of a multi display type VDT work is increased efficiency by dividing software into 2 displays. Workload, sense of incongruity, skills required for operation and other possible problems must be examined before spreading this approach becomes widespread in workplaces.

View full abstract

In three-dimensional display systems, binocular disparity must be limited within a certain area, called as “Panum's fusional area”. Otherwise, unsuitable binocular disparity can cause double view or eye fatigue. In this study we fully measured the limits of binocular fusional area in sixteen different directions from 0 degree to 360 degrees by a step of 22.5 degrees in the retinal fovea, using a three-dimensional display device. The following results were obtained: (1) the horizontal limit of Panum's fusional area in retinal fovea is larger than the vertical limit; (2) the limits of Panum's fusional area are almost symmetrical about the horizontal meridian; (3) the nasalward limits are obviously larger than the temporalward limits; (4) In nasal side of retina, the limits increase in a monotonic fashion; however in temporal side, the limits have no obvious change.

View full abstract

In this study, we measured the wavelength difference limit for binocular color vision, using a three-dimensional display to present dichoptic stimuli to the left and right eye, respectively. The size of stimulus was 2° are of visual angle, the wavelength range of the stimuli was selected from 450nm to 650nm, and the brightness of the experimental stimuli was set four levels, as 3cd/m², 7.5cd/m², 15cd/m², and 30cd/m². The following results were obtained: (a) the binocular color fusion ceases when the color difference introduced between the left and right eyes exceeds a certain threshold value. The range of binocular color fusion limit is less than 10-80nm. (b) The limit of binocular color fusion becomes smaller with the increase of the brightness of the stimulus.

View full abstract

This research compared CARS based on a computer system and ROMUM based on manual operation to measure the robot work. Time, accuracy, and usability of the analysis were selected as an evaluation index. In general, even though test results showed that the difference of the analysis time and the rate of error between computer work (CARS) and manual work (ROMUM) increased as the difficulty increased, there was not a certain linear relationship between these two works. This research discussed CARS developed as a computer supported system to measure the work time of a robot by attempting human-interface aspect to substitute the manual work measurement method based on PTS. The CARS was constructed as computer supported user oriented menu-driven type by taking advantage of ROMUM techniques. Therefore, compare to existing analytical method based on detailed basic motion, CARS could pursue the usability for user by selecting a module of unit motion according to the work content, minimize the analysis effort, and prevent errors as an effective work measurement system. Also, it might recognize unnecessary motion in advance and prevent execution of unnecessary motion by employing the analysis method according to the work content

View full abstract

This paper evaluates stress factors to effect on jobs and develops the evaluation model to apply the ma nufacturing workplaces. There are many psychosocial approaches and risk assessment tools to evaluate a job stress and muscularskeletal complaints that are attributed to hazardous occupations, but the exact etiology of these stress/disorders are currently unclear. The researches, however, indicate that these problems are multi-factorial and complicated with physical, psychosocial and environmental factors. Therefore we developed the integrated model considering those factors for the job stress evaluation in manufacturing workplaces.

View full abstract

The objective of this study was to find the musculoskeletal stress problems at chicken farms in Korea. One typical chicken farm was surveyed in this study. NLE (NIOSH Lifting Equation), REBA (Rapid Entire Body Assessment), and OWAS (Ovako Working Analysis System) were used to evaluate the extent of the musculoskeletal stress. It was found that there were some tasks which required fast innovation. It was also found that the RWL (Recommended Weight of Lift) was 4.6Kg. that was lower than weights which were handled by these workers.

View full abstract

This study focused on basic research for establishing a method of teaching bathing techniques to beginners. By analyzing the palm contact pressure of a midwife supporting the head of a newborn baby, this study aimed to clarify how an experienced person uses their hands. The subjects were five right-handed qualified midwives aged 34 to 46 years with 5 years or longer of continuous experiences in bathing newborns. To evaluate the contact between the subject and the bathing doll, a sheet-type body pressure distribution measurement system (BIG-MAT2000 by Nitta Corp.) was used. The subject held the bathing doll in both hands at the bosom and places the bathing doll into the bathtub using the left hand only. These actions were classified into the double-hand holding and single-hand holding patterns. Each action was measured for 6 seconds five times in a row. Of these measurements, two measurement results that were comparatively free from noise were adopted as measurement data. Pressure distribution on the entire palm at bathing indicated three-point support in both the double-hand holding and single-hand holding patterns, as reported in an earlier study.

View full abstract

The aim of this study was to investigate the relationship between the practice midwifery, including services such as birth and bathing assistance, and lower back pain in midwives. The questionnaire survey was carried out to the midwives and the valid response of 89 was obtained. This study showed that the majority of the midwives surveyed had a history of lower back pain. Moreover, height adjustment within the workplace to meet the midwives' height is integral to the reduction of the stress associated with the practice of midwifery.

View full abstract

Recently in Japan, with the enactment of the Transport Accessibility Improvement Law, many Braille signs and tactile guide maps have been installed at various public facilities. However, because many printing companies insufficiently knowledgeable about Braille signs and tactile guide maps have entered this field, many unsatisfactory products have appeared. It has been pointed out that tactile-symbols among different printing companies are unequal in shape and size. It is hoped that several basic studies of tactile-symbols and texture for tactile guide maps will be conducted to discover optimal standards. The Japanese Standards Association is now actively conducting projects that are expected to derive standardized methods for displaying tactile guide maps. In this study, we conducted two basic experiments. The first experiment investigated discriminable tactile-symbol size for three normal tactile symbols (circle, triangle and square). We found the minimum easily discriminable tactile-symbol sizes for each symbol. The second experiment examined useful dot-pattern texture for tactile guide maps. It was found that perception of dot-pattern texture correlates directly with the dot distance. Our findings may be helpful in efforts to derive a standardized method of displaying tactile guide maps.

View full abstract