• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.190-192
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• 2006

The clinical characteristics of photodamaged skin, such as coarse and fine wrinkle are not accurately evaluable with previous methods. Public awareness for wrinkle treatment and prevention which rely on proper assessment and evaluation of the underlying skin changes has been increased as the population ages. In this paper, we suggest an in-vivo method and instrument that allow us to acquire a wrinkle-enhanced image to improve the accuracy of quantitative and qualitative analysis for skin wrinkle. The method used involved white LED illumination and photography through polarizing filters. Finally, the polarized light photography yields an accurate and evaluable parameter of photodamaged skin, especially fine and coarse wrinkle.

• Journal of the Speleological Society of Korea
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• no.89
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• pp.16-23
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• 2008

In the cave, there are three kinds of CO2 gas from the human body and humidity or H2O from the underground water and also light from illumination fixture creating plants by photosynthesis. For this reason, the green plants of moss created and lived on the rock in the cave, but sometimes there would be the dry season to be killed the green mosses and hence, it could be dried and blackish. When the dried mosses were taken off from the surface of the rock like as laminated dried one, the moss lamination could be taken off together with the skin of the formated stalactite in the cave. Therefore, cave environment should be changed and degenerated. So it is useful and necessary to get selective wave lighting to have photosynthesis in the cave or not to have it in there by using of the LED lamps.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.605-608
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• 1996

The aim of this thesis is to develop a SMT-components placement inspection system equipped with a visual sensor. The visual sensor, which consists of a camera and 2-layer LED illuminator, developed to inspect the component placement state such as missing, shift, flipping, polarity and tomb-stone. on PCB in the reflow-process. In practical applications, however, it is too hard to classify component from images mixed pad on PCB, cream solder paste and component. To overcome the problem, this thesis proposes the 2-layer illumination method and the heuristic image processing algorithms according to inspection type. To show the effectiveness of the proposed approach, a series of experiments on the inspection were conducted. The results show that the proposed method is robust to visual noise and variations in component conditions.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.6 no.2
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• pp.95-99
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• 2006

A tape feeder of a SMD(Surface Mount Device) mounter is a device that sequentially feeds electronic components on a tape reel to the pick-up system of the mounter. As components are getting much smaller, feeding accuracy of a feeder becomes one of the most important factors for successful component pick-up. Therefore, it is critical to keep the feeding accuracy to a specified level in the assembly and production of tape feeders. This paper describes a tape feeder inspection system that was developed to automatically measure and to inspect feeding accuracy using machine vision. It consists of a feeder base, an image acquisition system, and a personal computer. The image acquisition system is composed of CCD cameras with lens, LED illumination systems, and a frame grabber inside the PC. This system loads up to six feeders at a time and inspects them automatically and sequentially. The inspection software was implemented using Visual C++ on Windows with easily usable GUI. Using this system, we can automatically measure and inspect the quality of ail feeders in production process by analyzing the measurement results statistically.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.2
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• pp.133-139
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• 2011

We have performed optical design of light guide plates (LGPs) for a photobioreactor by using an illumination design tool. An LGP having light emitting diodes (LEDs) as a light source on the four sides was designed by optimizing the distribution of LGP patterns and design of another LGP, on top of which sunlight was focused by a Fresnel lens, was executed. Finally, a hybrid-solar-and-LED-lighting scheme was described. Detailed design process and optical performances of the designed LGPs are presented.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.9
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• pp.844-847
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• 2008

The photo leakage currents of a conventional hydrogenated amorphous silicon(a-Si:H) thin film transistor(TFT) were investigated and analyzed in case of illumination from various light sources such as halogen lamp, cold cathode fluorescent lamp(CCFL) backlight, and white light emitting diode(LED) backlight. The photo leakage characteristics showed the apparent differences in the leakage level and in the $I_{on}/I_{off}$ ratio in spite of the similar luminances of light sources. This leakage level is expected to be related to the wavelength of the lowest intensity peak from the spectral characteristics of light sources.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.179-181
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• 2009

보안구역의 외곽울타리지역의 경비체제를 인적경비에서 과학화경비로 전환함에 따라 CCTV 카메라 및 모니터 기능이 보다 향상되고 있는 반면에 이에 따른 조명설비의 중요성이 인식되었다. 그러므로 본 논문에서는 보안구역 내 과학화된 보안시스템에 적합한 조명개선을 위하여 기존 시설된 고압나트륨과 시범 설치된 LED 광원 및 조명등주의 위치를 변경하면서 조도를 실측하였다. 또한 CCTV 감시 화면의 특성을 고려하여 정확한 물체를 확인 할 수 있는 명암을 유지하기 위한 조명 값을 구하기 위하여 시뮬레이션을 실시하여 조도 개선안을 제시하고자 한다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.4
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• pp.364-371
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• 2010

In this paper, we propose the landscape lighting power control system with solar sell generator equipment for energy saving, and also which is included the landscape lighting power transformation device. The power transformation device can check inverse current in the power of the solar cell module and control the power of the battery. And we present the design of landscape lighting power control system. The power control system uses microprocessor with charging system and power transformation device. And also it can control the power of loads under consideration intensity of illumination. The landscape lighting loads are composed of LED(Lighting Emitting Diode) and HID(High Intensity Discharge)lamps. To evaluate property, we installed the solar cell array which generate three kilo watt power. Experimental results show that the proposed system can have stability and energy saving on the mixed configuration of electric loads with DC and AC lamps.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.543-545
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• 2019

Recently, the demand for smart farms is increasing due to the increase in the cultivation area such as horticulture, fruit trees and special crops. However, due to the irregular weather changes and the cultivation method of the crops due to the different cultivation environment, there are frequent occurrence of diseases and insect pests and infectious diseases due to system error or carelessness, and the cycle is also very short. In addition, the Smart Farm business has been built by combining various sensors (temperature, humidity, CO2, illumination) and LED lighting, but it is costly in terms of frequent errors, lack of power supply, And thus the management can not be efficiently managed. Therefore, this paper combines real time sensing technology based on IoT Platform and high performance control technology to control pests and equipment errors and monitor the growth status of crops in real time based on big data analysis and Artificial Intelligence System.

• Advances in materials Research
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• v.3 no.4
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• pp.227-232
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• 2014

$Ce^{4+}$, $Eu^{3+}$, $Tb^{3+}$ co-doped $Ca_3Si_3O_8F_2$ phosphor was synthesized via solid state reaction method using $CaF_2$, $CaCO_3$ and $SiO_2$ as raw materials for the host and $Eu_2O_3$, $CeO_2$, and $Tb_4O_7$ as activators. The luminescent properties of the phosphor was analysed by spectrofluorophotometer at room temperature. The effect of excitation wavelengths on the luminescent properties of the phosphor i.e. under near-ultraviolet (nUV) and visible excitations was investigated. The emission peaks of $Ce^{4+}$, $Eu^{3+}$, $Tb^{3+}$ co-doped $Ca_3Si_3O_8F_2$ phosphor lays at 480(blue band), 550(green band) and 611nm (red band) under 380nm excitation wavelength, attributed to the $Ce^{4+}$ ion, $Tb^{3+}$ ion and $Eu^{3+}$ ions respectively. The results reveal that the phosphor emits white light upon nUV (380nm) / visible (465nm) illumination, and a red light upon 395nm / 535nm illumination. RE ions doped $Ca_3Si_3O_8F_2$ is a promising white light phosphor for LEDs. The emission colours can be seen using Commission international de l'eclairage (CIE) co-ordinates. A single host phosphor emitting different colours under different excitations indicates that it is a potential phosphor having applications in many fields.