There has recently been a significant increase in the number of diabetic patients. Self-monitoring of the glucose levels in a patient's blood is essential for treating diabetes. Generally, blood glucose measurement requires an invasive blood sampling. Therefore, patients are always plagued by issues such as pain, stress, and risk of blood-borne infection. The objective of this study is to develop a non-invasive blood glucose measurement device based on NIR spectroscopy. We compared the prediction accuracy of the individual calibration curve and summarized calibration curve, and took the analysis wavelength range into consideration as fundamental experiments for taking a non-invasive blood glucose measurement. As a result, a clinically effective level of accuracy and a high correlation were confirmed in the individual calibration curve, and an analysis using a smaller wavelength range has a good influence on the accuracy.
This study aims to clarify color rendering properties for two-color combinations when the spectral power distributions of light sources including LED lamps and illuminance change and also aims to calculate the color rendering values while taking illuminance into consideration. Subjects subjectively evaluated the feelings of the two-color combinations of the test side by comparing them with the feelings of those of the reference side by using the Semantic Differential method. In the results, affective evaluation values decreased for all test light sources when illuminance decreased. However, for the red and green combination samples, affective feelings under 10 lx of the LED lamp (LED-RGB) of the combination of red-green-blue LED are almost the same as those under 700 lx of the other light sources. Also, we tried to calculate the color rendering values while takingilluminance into consideration. There was no correlation between affective evaluation values and the color rendering values at anyilluminance level. The results suggested that the current CIE-Ra, CIECAM02-Ra, and CIECAM02UCS-Ra are not be sufficient when color rendering properties are evaluated at low illuminace.
Light pollution due to outdoor lighting results in a delayed heading time and reduced yield in rice. We investigated the effect of light pollution by a method whereby rice grows in a paddy field exposed to three sources of outdoor illuminations: commercial LED illumination, a special LED illumination, and a mercury lamp. We examined effects of heading time and yield in rice when Oryza sativa L. cv. Hinohikari was irradiated by each kind of illumination at night. In the results, for irradiation by a common LED illumination and a mercury lamp, heading time was delayed and yield was reduced with increased illuminance, indicating the occurrence of light pollution. However, for irradiation by a special LED illumination, delayed heading time was unlikely to occur and the reduction in yield was small, indicating less light pollution.
Recently, LED lighting has become widely used in offices and schools. Thus workers and students have to do visual task under artificial light for several hours a day. In this study, we compared the effect of CCT and the spectral distribution of light sources on visual fatigue using four light sources including white LED and fluorescent lamps. Significant differences were found in the reduced ability on eyes to focus among the four lamps. Results also showed that the narrower the spectral band width of the light source, the larger the decreasing rate of accommodation. This suggests that the spectral distribution of a light source affects the ease of accommodation.