• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.7 no.1
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• pp.20-25
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• 2014

There are several severe problems for LED device, the next generation's economy green lighting: as the temperature increases, the lamp efficiency decreases; if the temperature is over $80^{\circ}C$, the lifetime of lighting decreases; Red Shift phenomenon that wavelength of spectrum line moves toward long wavelength occurs; and optical power decreases as $T_j$ increases. Thus, Heat sink design that can minimize the heat of LED device is currently in progress. While the thermal resistance of COB Type LED was reduced by direct coupling of LED chip to the board, residential 13.5W requires Heat sink in order resolve heat issue. This study designed Heat Sink suitable for residential 13.5W COB LED down-light and selected the optimum Fin thickness through flow simulation that packaged the designed Heat Sink and 13.5W COB. And finally it analyzed and evaluated the thermal modes using contacting thermometer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.387-388
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• 2010

• Advances in materials Research
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• v.3 no.3
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• pp.129-137
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• 2014

Biocomposites from polypropylene (PP) and corn cob (CC) were investigated. The effect of corn cob content and maleic anhydride polypropylene (MAPP) as compatibilizer were studied. Results showed that addition of corn cob (CC) in PP have decreased the tensile strength and elongation at break, whereas modulus of elasticity of biocomposites increased. The biocomposites with the MAPP as compatibilizer exhibited higher tensile strength and modulus of elasticity compared biocomposites without MAPP. The morphology study of biocomposites indicates that enhanced the interfacial interaction and adhesion between filler and matrix with the presence of MAPP.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.2
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• pp.158-163
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• 2013

In this paper, thermal analysis of heatsink for 30 W class Chip-on-Board (COB) LED light source is performed by using SolidWorks Flow Simulation package. In order to increase the convection heat transfer, number of fin and shape of the heatsink is optimized. Furthermore, a copper spread is applied between the COB LED light source and the heatsink to mitigate the heat concentration on the heatsink. With the copper spread, the junction temperature between the COB LED light source and the heatsink is $50.9^{\circ}C$, which is $5.4^{\circ}C$ lower than the heatsink without the copper spread. Due to the improvement of the junction temperature, the light output is improved by 5.8% when the LED light source is stabilized. The temperature difference between the simulation and measured result of the heatsink with the copper spread is within $2^{\circ}C$, which verifies the validity of the thermal design method using a simulation package.

• Korean Journal of Optics and Photonics
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• v.21 no.3
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• pp.118-122
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• 2010

We fabricated a high power LED lamp structure which utilizes the modified COB concept based on an MCPCB with insulation layer partially removed. In the proposed structure, no insulation layer exists between the LED chip and the metal base. As a result, the heat generated in the chip is easily dissipated through the metal base. In actual measurement as well as in thermal simulation, the fabricated LED lamp structure showed superb thermal properties, compared to the SMD LED lamp attached on an MCPCB or the LED lamp based on conventional COB concept.

• Journal of Forest and Environmental Science
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• v.37 no.1
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• pp.79-89
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• 2021

Cement bonded boards of 10 mm in thickness were produced from the mixture of Gmelina arborea sawdust and corn cob particles. The strength and dimensional stability of cement bonded composites produced from these two mixtures were examined. A total of thirty experimental boards were produced at density level of 1,000 kg/㎥ with cement to fibre ratio of 2.5:1 and 3:1 and five (5) blending proportions of G. arborea sawdust to corn cob particles of 100:0; 75:25; 50:50; 25:75 and 100:0. The effect of the cement to fibre ratio and blending proportion on the Water Absorption (WA), Thickness Swelling (TS), Modulus of Rupture (MOR), and Modulus of Elasticity (MOE) were determined. The result indicates that as the mixing ratio of cement to fibre and blending proportion of maize cob (75%) to G. arborea (25%) increased, the thickness swelling, water absorption decreased, whereas the MOR and MOE increased. It also shows that most dimensionally stable and flexural strength boards were produced at the highest level of mixing ratios (3:1) and blending proportion of G. arborea to corn cob 25:75. However, the analysis of variance shows that TS and WA were significantly different, whereas, MOE and MOR were not significantly affected by mixing ratios and blending proportions. Finding of this study has shown that maize cob particles are suitable for cement bonded board production.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.55-55
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• 2022

Purple com Saekso 1 was developed by Maize Research Institute (Hongcheon, Gangwon, Korea) and registered in 2011. Saekso 1 is a anthocyanin-rich hybrid variety that is yellow grain, purple husk and cob. Purple husk and cob of Saekso 1 is as a resource for the bioactive material by health food. In order to investigate optimum sowing date and planting density of Saekso 1. Agronomic characteristics were compared by sowing times April 25, May 15 and June 5. Husk dry weight were 68,72 and 70kg·10a-1, respectively. Cob dry weight were 90, 92 and 92kg·10a-1, respectively. Content of cyanidin-3-glucoside in husk were 0.56, 0.62 and 0.56% and in cob were 0.19, 0.14 and 0.17%. Therefore, the sowing time to increase husk and cob weight and content of cyanidin-3-glucoside is appropriate for planting in mid-May. The number of plants in planting density trial was 9,400, 7,000, 5,700 and 4,700 plants in 10a area. Plant height at each trial were 249, 250, 246 and 248cm, respectively. Husk dry weight were 76, 67 and 63 and 60kg·10a-1, respectively. Cob dry weight were 112, 92, 87 and 81kg·10a-1, respectively. Content of cyanidin-3-glucoside in husk were 0.70, 0.71, 0.71 and 0.75% and in cob were 0.21, 0.28, 0.26 and 0.20%. Therefore, appropriate sowing time was in mid-May and planting density was 5,700~7,000 plants·10a-1 in order to increase the yield and content of cyanidin-3-glucoside of purple com in South Korea.

• ALGAE
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• v.29 no.1
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• pp.15-25
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• 2014

The number of species of non-native and invasive marine algae is growing, with concomitant public concern about native ecosystems and coastlines. Gelidium vagum, recently introduced from northeast Asia to Europe and North America, commonly occurs from the intertidal to subtidal zones in Korea, China, and Japan. To investigate the level of genetic diversity of native populations, we analyzed mitochondrial cox1 and cob from 108 specimens of G. vagum from Korea, China, eastern Russia, including from the Netherlands and USA. The haplotype network of individual and cox1 + cob datasets revealed no genetic structure in local populations, suggesting genetic flow between Korean populations. Our results corroborate a typical pattern of genetic diversity for introduced species, with low levels in introduced populations and high levels in native populations. All haplotypes were shared between the Netherlands and USA, but not between Korea and the Netherlands / USA except cox1. Additional sampling will identify donor populations in native northeast Asian waters. This is the first report of the utility of the mitochondrial coding cob sequences in red algae.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.15 no.2
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• pp.147-155
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• 1993

The combined induction chemotherapy is usually used to treat the advanced head and neck cancer. In particular, it is considered that the COB(Cisplatin, Oncovin, Bleomycin)regimen is very effective against the squamous cell carcinoma in head and neck region. The purpose of this study is to evaluate the cancer tissue response to chemotherapy (COB Regimen) histopath ologically.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1722-1723
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• 2011

LED는 광학적 특성을 유지하기 위해서는 방열설계가 매우 중요한 문제로 요구된다. 대부분의 반도체 소자의 고장 원인은 85%정도가 열로 인한 것이며 고출력 LED의 인가된 에너지는 20%정도가 광으로 출력되며 나머지 80%정도가 열로 전환된다. 이러한 이유 때문에 LED소자의 신뢰성과 효율 향상을 위한 방열성능의 극대화가 필요하다. 본 연구에서는 AI MCPCB 기판에 기반을 둔 COB Type의 고출력 LED모듈의 구조를 제안 하였으며, LED Chip과 금속base 사이의 절연층 유무의 관점에서의 비교 열 시뮬레이션을 통해 결과를 분석하여 고출력 COB LED모듈의 방열 특성을 최적화 하였다.