• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.11
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• pp.949-956
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• 2016

There are a number of effects by solar radiation in many aerospace industrial fields, such as degradation of mechanical properties, sealing effect of sealants or decolorization. Because it takes long time to investigate these effects by using the light of natural state, new methods are developed for accelerating this phenomenon. In this paper, we developed an apparatus to simulate accelerated solar radiation phenomenon selecting irradiation intensity $1,120W/m^2$ as the designed environment. Epoxy polymer as the composite material was chosen and processed by ASTM-D638, a reference for tensile test of polymer and plastic. Total color shift was selected as the test category to evaluate acceleration of the test. We obtained acceleration factors and numerical model from test data and concluded it can shorten test periods by accelerated irradiation intensity of $1,120W/m^2$.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.2
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• pp.44-52
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• 2012

As an alternative strategy in the era of high level petroleum cost, the study focused to suggest the way on the revitalization of renewable energy through the impact on introduction effect of renewable energy in green village. Total feasible solar energy production is 6.73 GWh/yr along with the biomass energy producing electric power energy is 134.06 GWh/yr, the two category's total electric power energy is 233.19 GWh/yr, which is possible to achieve the selfsufficiency of energy by 33% for total energy consumption of 705.80 GWh/yr in the region. The calculated feasibility on the carbon dioxide reduction, carbon dioxide reduction level is 1,891 ton_$CO_2$ by agricultural byproducts, 43,635 ton_$CO_2$ by livestock waste, 395 ton_$CO_2$ by municipal waste, 50,324 ton_$CO_2$ by forest byproducts, the total biomass shows 96,245 ton_$CO_2$, while the carbon dioxide reduction of solar light energy is 2,251 ton_$CO_2$, 1,383.3 ton_$CO_2$ by solar heat energy, the total solar energy shows 3,634 ton_$CO_2$. So total carbon dioxide reduction effect shows 99,879 ton_$CO_2$.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.105-113
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• 2013

In this paper a micro solar energy harvesting system with MPPT(Maximum Power Point Tracking) control using a miniature PV(photovoltaic) cell of which the output is less than 0.5V is proposed. The MPPT control is implemented using linear relationship between the open-circuit voltage of a PV cell and its MPP(Maximum Power Point) voltage such that a pilot PV cell can track the MPP of the main PV cell in real time. The proposed circuit is designed in 0.18um CMOS process. The designed chip area is $900um{\times}1370um$ including a load charge pump and pads. Measured results show that the designed system can track the MPP voltage changes with variations of light intensity. The designed circuit with MPPT control delivers MPP voltages to load even though the load is heavy such that it can supply more power when the MPPT control is applied. The proposed circuit does not require any precharged battery resulting in more suitability for miniaturized self-powered systems compared to the existing works.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.71-71
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• 2011

Dye-sensitized solar cells (DSCs) have drawn great academic attention due to their potential as low-cost renewable energy sources. DSCs contain a nanostructured TiO2 photoanode, which is a key-component for high conversion efficiency. Particularly, one-dimensional (1-D) nanostructured photoanodes can enhance the electron transport for the efficient collection to the conducting substrate in competition with the recombination processes. This is because photoelectron colletion is determined by trapping/detrapping events along the site of the electron traps (defects, surface states, grain boundaries, and self-trapping). Therefore, 1-D nanostructured photoanodes are advantageous for the fast electron transport due to their desirable features of greatly reduced intercrystalline contacts with specified directionality. In particular, anodic TiO2 nanotube (NT) electrodes recently have been intensively explored owing to their ideal structure for application in DSCs. Besides the enhanced electron transport properties resulted from the 1-D structure, highly ordered and vertically oriented nanostructure of anodic TiO2 NT can contribute additional merits, such as enhanced electrolyte diffusion, better interfacial contact with viscous electrolytes. First, to confirm the advantages of 1-D nanostructured material for the photoelectron collection, we compared the electron transport and charge recombination characteristics between nanoparticle (NP)- and nanorod (NR)-based photoanodes in DSCs by the stepped light-induced transient measurements of photocurrent and voltage (SLIM-PCV). We confirmed that the electron lifetime of the NR-based photoanode was much longer than that of the NP-based photoanode. In addition, highly ordered and vertically oriented TiO2 NT photoanodes were prepared by electrochemical anodization method. We compared the photovoltaic properties of DSCs utilizing TiO2 NT photoanodes prepared by one-step anodization and two-step anodization. And, to reduce the charge recombination rate, energy barrier layer (ZnO, Al2O3)-coated TiO2 NTs also applied in DSC. Furthermore, we applied the TiO2 NT photoanode in DSCs using a viscous electrolyte, i.e., cobalt bipyridyl redox electrolyte, and confirmed that the pore structure of NT array can enhance the performances of this viscous electrolyte.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.4
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• pp.325-331
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• 2015

Skin is exposed to sunlight or artificial indoor light on a daily. The reached solar light on the earth surface consist of 50% visible light and 45% infrared (IR) except for ultra violet (UV). The negative effects of UV including UVB and UVA have been steadily investigated within the last decades. However, little is known about the effects of visible or IR light. In this study, we irradiated human dermal fibroblasts using light emitting diode (LED) to investigate the optimal parameter for enhancing cell growth and collagen synthesis. We found that red of 630 nm and green of 520 nm enhance the cell proliferation, but irradiation with purple and blue light exerts toxic effects. To examine the response of irradiation time and light intensity on the fibroblasts, cells were exposed to red or green light with intensities from 0.05 to $0.75mW/cm^2$. Procollagen secretion was increased of 1.4 fold by 10 min irradiation, while 30 min treatment decreased the collagen synthesis of dermal fibroblasts. Treatment with red of $0.3mW/cm^2$ and green of 0.15 and $0.3mW/cm^2$ resulted in enhancement of collagen mRNA. Lastly, we investigated the combinatorial effect of red and green light on dermal fibroblasts. The sequential irradiation of red and green light is an efficient way for the purpose of the increase in the number of fibroblasts than single light treatment. On the other hand, the exposure of red light alone was more effective method for enhancing of collagen secretion. Our study showed that specific light parameters accelerated cell proliferation, gene expression and collagen secretion on human dermal fibroblasts. In conclusion, we demonstrate that light exposure with specific parameter has beneficial effects on the function of dermal fibroblasts, and suggests the possibility of its cosmetically and clinical application.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.183-189
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• 2004

Deep ocean water is located in the sea deeper than 200m. At such depth the solar light does not reach, photosynthesis is not performed and nutrition salt is not consumed. Therefore, campared with surface water, Deep Sea Water contains more nutrition salt, such as nitrogen and phosphor. Moreover, it has the good balance of minerals. This Research is primary attempt for apply deep sea water to food industry. New type of mineral salt manufacturing system was developed and high levels of Ca, K, Mg detected from the salt analysis.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.48.2-48.2
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• 2010

고효율 실리콘 태양전지 개발은 단파장의 광 응답 특성 개선을 위한 선택적 에미터 형성과 반사 손실 개선을 위한 미세 패턴 전극을 형성하는데 집중적인 연구가 진행되고 있다. 본 실험에서는 레이저 도핑된 선택적 에미터 위에 미세 패턴 Ni/Cu 도금 전극을 형성하였다. 니켈과 동 도금은 무전해 Light induced plating(LIP)으로 진행하였다. 니켈 도금 전극의 접착력 개선과 접촉저항 개선을 위해서 니켈 전극을 질소 분위기에서 열처리하여 니켈실리사이드(NiSi)를 형성하였다. 니켈 도금 두께와 니켈실리사이드 열처리 조건을 최적화하여 충실도 77.4%, 변환효율 18.5%를 달성하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.274-274
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• 2009

고효율 결정질 실리콘 태양전지 구조를 갖기 위해서는 기본적으로 광포획 기능이 고려된 기판이 고려되어야 한다. 본 실험에서는 2-step 습식공정을 이용하여 기판의 반사율을 기존 대비 절반 이하로까지 줄일 수 있는 저반사율을 갖는 표면구조를 얻을 수 있었다. 일반적인 텍스처링 공정을 NaOH와 TMAH등을 이용하여 10um이하의 피라미드 구조를 통해 평균반사율을 10~13%수준을 얻었고, metal assist etching을 이용하여 추가적인 나노 텍스처링을 적용하였다. 전체적인 2-step에칭을 적용하여 평균 반사율을 5%이하까지 줄일 수 있었다. 이는 전반적으로 나노구조 형성으로 인하여 단파장쪽의 반사율이 적게 나오고 IR 파장쪽의 반사율도 같이 낮아짐으로써 저반사율이 달성되었다. 2-step을 이용한 나노 텍스처링 공정 최적화와 반사방지막을 증착하여 이에 대한 효과를 연구하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.332.2-332.2
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• 2016

Two dimensional transition-metal dichalcogenides (TMDs) semiconductors are attractive materials for optoelectric devices because of their direct energy bandgap and transparency. To investigate the feasibility of transparent p-n junctions, we have fabricated a p-n heterojunction consisting of p-type WSe2 and n-type MoS2 flakes since WSe2 and MoS2 with proper electrode metals exhibit p-type and n-type behaviors, respectively. These heterojunctions exhibits gate-tunable rectifying behaviors and photovoltaic effects (ECE ~ 0.2%) indicating that p-n junctions were formed. In addition, photocurrent and photovoltaic effects were observed under light illumination, which were dependent on the gate voltage. In addition, the photocurrent mapping images indicate that the photovoltaic effects comes from the junction area. Possible origins of gate-tunability are discussed.

• Journal of Aerospace System Engineering
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• v.6 no.4
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• pp.7-11
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• 2012

Recently, the renewable energy has been widely used as a wind energy and solar energy resource due to lack and environmental issues of the mostly used fossil fuel. In this situation, the interest in wind power has been risen as an important energy source. For this blade a high efficiency wind turbine blade was designed with the proposing aerodynamic design procedure, and a light and low cost composite structure blade was designed considering fatigue life. Structural analyses including load case study, stress, deformation, buckling, fatigue life and vibration analysis were performed using the Finite Element Method.