• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.307-316
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• 2014

Improved power conversion efficiency of hybrid solar cells with ITO/ZnO seed layer/ZnO NRs/ZnS QDs/P3HT/PCBM/Ag structure was obtained by optimizing the growth period of ZnO nanorods (NRs). ZnO NRs were grown using a hydrothermal method on ZnO seed layers, while ZnS quantum dots (QDs) (average thickness about 24 nm) were fabricated on the ZnO NRs by the successive ionic layer adsorption and reaction (SILAR) technique. Morphology, crystalline structure and optical absorption of layers were analyzed by a scanning electron microscope (SEM), X-ray diffraction (XRD) and UV-Visible absorption spectra, respectively. The XRD results implied that ZnS QDs were in the cubic phase (sphalerite). Other experimental results showed that the maximum power conversion efficiency of 4.09% was obtained for a device based on ZnO NR10 under an illumination of one Sun (AM 1.5G, $100mW/cm^2$).

• Korean Journal of Occupational Health Nursing
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• v.6 no.1
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• pp.5-13
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• 1997

For the purpose of investigating the subjective symptom of industrial fatigue, a questionnaire survey was carried out on 282 labor workers and 189 managerial workers who were employed at the manufacture of electronic products in two small scale industries. Checklist of industrial fatigue was composed of physical symptoms(10 items), mental symptoms(10 items), and sensory neurotic symptoms(10 items). The results were as follows : 1. Complain rate of fatigue was the highest in "eye strain" of physical symptom, "feel anxious about things" of mental symptom, and "feel stiffness in the neck or the shoulders" of sensory neurotic symptom in labor workers and managerial workers. 2. Managerial workers demonstrated II dominant type (mental or night work type), while labor workers demonstrated I dominant type of fatigue (general type). 3. Mean weighted score of fatigue complaints in labor workers (23.16) was significantly higher than that in managerial workers (20.34). 4. Mean weighted scores of fatigue complaints in male, 5~9 years of work duration, married, 4~5 hours of sleeping time, graduation of high school and college, and large of workload were significantly higher in labor workers than in managerial workers. 5. In poor work condition with temperature, ventilation, illumination and noise, the average weighted score was significantly higher in labor workers than in managerial workers.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.3
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• pp.1-9
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• 2005

Light is an important environmental element for people to live and do creative activities in residential areas. Especially, people are used to live under artificial light in artificial interior surroundings for the most times. Currently, the lighting quality of residential areas has been improved, but it still does not reach to the recommended level because the luminous environment of present residential areas is only based on the life behavior which puts its priority to clear vision. Therefore, it is necessary that proper standard illumination must be used for various uses and purposes. From this point of view, this paper investigated the essence of light in residential areas, and the luminous environment for apartments was measured This paper finally established well-coordinated standard illuminance, derived from the measurement and analysis of luminous environment from these cases.

• Agricultural and Biosystems Engineering
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• v.1 no.2
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• pp.106-110
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• 2000

An integrated on-line inspection system was constructed with seven cameras, half mirrors to split images. 720 nm and 970 nm band pass filters, illumination chamber having several tungsten-halogen lamps, one main computer, one color frame grabber, two 4-channel multiplexors, and flat plate conveyer, etc. A total of seven images, that is, one color image form the top of an apple and two B/W images from each side (top, right and left) could be captured and displayed on a computer monitor through the multiplexor. One of the two B/W images captured from each side is 720nm filtered image and the other is 970 nm. With this system an on-line grading software was developed to evaluate appearance quality. On-line test results with Fuji apples that were manually fed on the conveyer showed that grading accuracies of the color, defect and shape were 95.3%, 86% and 88.6%, respectively. Grading time was 0.35 second per apple on an average. Therefore, this on-line grading system could be used for inspection of the final products produced from an apple sorting system.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.802-811
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• 1996

Farmers need alternatives for weed control due to the desire to reduce chemicals used in farming. However, conventional mechanical cultivation cannot selectively remove weeds located in the seedline between crop plants and there are no selective heribicides for some crop/weed situations. Since hand labor is costly , an automated weed control system could be feasible. A robotic weed control system can also reduce or eliminate the need for chemicals. Currently no such system exists for removing weeds located in the seedline between crop plants. The goal of this project is to build a real-time , machine vision weed control system that can detect crop and weed locations. remove weeds and thin crop plants. In order to accomplish this objective , a real-time robotic system was developed to identify and locate outdoor plants using machine vision technology, pattern recognition techniques, knowledge-based decision theory, and robotics. The prototype weed control system is composed f a real-time computer vision system, a uniform illumination device, and a precision chemical application system. The prototype system is mounted on the UC Davis Robotic Cultivator , which finds the center of the seedline of crop plants. Field tests showed that the robotic spraying system correctly targeted simulated weeds (metal coins of 2.54 cm diameter) with an average error of 0.78 cm and the standard deviation of 0.62cm.

• Journal of Biosystems Engineering
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• v.32 no.2 s.121
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• pp.130-135
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• 2007

An on-line real time grading and sorting system for dried oak mushrooms was developed for on-site application. Quality grades of the mushrooms were determined according to an industrial specification. Three dimensional visual quality features were used for the grading. A progressive color computer vision system with white LED illumination was implemented to develop an algorithm to extract external quality patterns of the dried oak mushrooms. Cap (top) and gil (stem) surface images were acquired sequentially and side image was obtained using mirror. Algorithms for extracting size, roundness, pattern and color of the cap, thickness, color of the gil and amount of rolled edge of the dried mushroom were developed. Utilizing those quality factors normal and abnormal ones were classified and normal mushrooms were further classified into 30 different grades. The sorting device was developed using microprocessor controlled electro-pneumatic system with stainless buckets. Grading accuracy was around 97% and processing time was 0.4 s in average.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.5
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• pp.423-428
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• 2005

This paper proposes a new edge detection method using a $3{\times}3$ ideal binary pattern and lookup table (LUT) for the mobile robot localization without any parameter adjustments. We take the mean of the pixels within the $3{\times}3$ block as a threshold by which the pixels are divided into two groups. The edge magnitude and orientation are calculated by taking the difference of average intensities of the two groups and by searching directional code in the LUT, respectively. And also the input image is not only partitioned into multiple groups according to their intensity similarities by the histogram, but also the threshold of each group is determined by fuzzy reasoning automatically. Finally, the edges are determined through non-maximum suppression using edge confidence measure and edge linking. Applying this edge detection method to the mobile robot localization using projective invariance of the cross ratio. we demonstrate the robustness of the proposed method to the illumination changes in a corridor environment.

• ETRI Journal
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• v.35 no.4
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• pp.587-593
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• 2013

We demonstrate semitransparent organic photovoltaics (OPVs) based on thin metal electrodes and polymer photoactive layers consisting of poly(3-hexylthiophene) and [6,6]-phenyl $C_{61}$ butyric acid methyl ester. The power conversion efficiency of a semitransparent OPV device comprising a 15-nm silver (Ag) rear electrode is 1.98% under AM 1.5-G illumination through the indium-tin-oxide side of the front anode at 100 $mW/cm^2$ with 15.6% average transmittance of the entire cell in the visible wavelength range. As its thickness increases, a thin Ag electrode mainly influences the enhancement of the short circuit current density and fill factor. Its relatively low absorption intensity makes a Ag thin film a viable option for semitransparent electrodes compatible with organic layers.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1761-1767
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• 2015

This paper deals with the solar tracking performance using a small heliostat, the light reduction rate of the sun light, and the performance of uniform irradiation of LED light for a plant factory. A high precision encoder is attached to the heliostat to improve tracking accuracy. As a result, our heliostat-based solar tracking systems track efficiently the movement of the sun light in experimental tests. The reduction rate of the sun light in the plant factory is then measured by using an illumination sensor. The average reduction rate is 4.29%, which represents lower light reduction rates. In uniform irradiation tests of LED light, sixteen points are measured, and overall deviations of irradiation were within eight percents.

• Journal of the Optical Society of Korea
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• v.16 no.4
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• pp.449-456
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• 2012

For two well-known modulation methods, stepwise current modulation (SCM) and pulse width modulation (PWM), the effects of driving current modulation conditions on chromaticity were experimentally investigated in a white LED lighting system. For the experimental implementation of both SCM and PWM, a white LED lighting was fabricated using phosphor converted (PC) white light emitting diodes (LEDs) and a driving circuit module was developed. By using them, the variations of illuminance, color coordinates, and spectrum were evaluated under various forward current conditions. Through the analysis in color coordinates, yellow shift in SCM and blue shift in PWM were observed on chromaticity diagrams with increasing average driving current. In addition, in order to analyze color deviation quantitatively, color distance before and after current increase, and the correlated color temperature (CCT) were calculated. As a result, for the white LED lighting in both modulation conditions, the maximum difference in the calculated CCT was obtained close to 1000 K. It means that careful consideration is required to be taken in the design of illumination systems to avoid serious problems such industrial accidents.