• Bulletin of the Korean Chemical Society
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• 제31권8호
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• pp.2185-2189
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• 2010

Closely arranged CdSe and Zn doped CdSe vertical nanorod bundles were grown directly on FTO coated glass by using electrodeposition method. Structural analysis by XRD showed the hexagonal phase without any precipitates related to Zn. FE-SEM image showed end capped vertically aligned nanorods arranged closely. From the UV-vis transmittance spectra, band gap energy was found to vary between 1.94 and 1.98 eV due to the incorporation of Zn. Solar cell parameters were obtained by assembling photoelectrochemical cells using CdSe and CdSe:Zn photoanodes, Pt cathode and polysulfide (1M $Na_2S$ + 1M S + 1M NaOH) electrolyte. The efficiency was found to increase from 0.16 to 0.22 upon Zn doping. Electrochemical impedance spectra (EIS) indicate that the charge-transfer resistance on the FTO/CdSe/polysulfide interface was greater than on FTO/CdSe:Zn/polysulfide. Cyclic voltammetry results also indicate that the FTO/CdSe:Zn/polysulfide showed higher activity towards polysulfide redox reaction than that of FTO/CdSe/polysulfide.

• 항공우주기술
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• 제3권2호
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• pp.11-19
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• 2004

버스전압이 배터리 전압과 동일하며, 전력조절기(power regulator)의 스위칭 듀티 값(duty-ratio)이 위성탑재 소프트웨어에 의해서 제어되는 소프트웨어 제어방식의 비 조절형 버스 시스템(unregulated bus system)은 저궤도 위성에 흔히 사용된다. 본 논문에서는 이와 같은 소프트웨어 제어방식의 비 조절형 버스 시스템의 전력조절기 모듈화에 적용 가능한 새로운 전원단 회로를 제안하며, 제안된 전원단의 모드별 동작 특성을 해석한다. 다음으로 컨버터 병렬동작에서 발생할 수 있는 모듈간 전류 불균형(current unbalance)에 대한 제안된 전원단의 타당성을 검증하기 위해 제안된 전원단을 적용한 병렬모듈 컨버터의 prototype을 제작하여 모듈별 전류 분배(current sharing) 특성을 시뮬레이션 결과와 비교 검토한다.

• 한국기계가공학회지
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• 제14권4호
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• pp.73-84
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• 2015

Electricity generation using fossil fuels has caused environmental pollution. To solve this problem, research on new renewable energy sources (solar, wind power, geothermal heat, etc.) to replace fossil fuels is ongoing. These devices are able to generate power consistently. However, they have many weaknesses, such as high installation costs and limits to possible setup environments. Therefore, an active study on piezoelectric harvesting technology that is able to surmount the limitations of existing energy technologies is underway. Piezoelectric harvesting technology uses the piezoelectric effect, which occurs in crystals that generate voltage when stress is applied. Therefore, it has advantages, such as a wider installation base and lower technological costs. In this study, a piezoelectric harvesting device imitating seaweed, which has a consistent motion caused by fluid, is used. Thus, it can regenerate electricity at sea or on a bridge pillar, which has a constant turbulent flow. The components of the device include circuitry, springs, an electric generator, and balancing and buoyancy elements. Additionally, multiphysics analysis coupled with fluid, structure, and piezoelectric elements is conducted using COMSOL Multiphysics to evaluate performance. Through this program, displacement and electric power were analyzed, and the actual performance was confirmed by the experiment.

• 대한화장품학회지
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• 제35권4호
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• pp.317-323
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• 2009

지속적인 자외선 노출은 사람의 피부에 주름 형성을 유발한다. 본 연구에서 생강나무 추출물이 광노화에 의한 피부 주름 형성의 개선에 미치는 효능을 검증해 보고자 하였다. 우선 사람 섬유아세포를 이용하여 생강나무 추출물의 세포증식과 타입 I 콜라겐의 생합성 활성을 측정하였다. 그 결과 생강나무 추출물에 의한 세포증식과 타입 I 콜라겐의 생합성능은 대조군과 비교하여 각각 33.8 %와 91.8 % 증식함을 보였다. 동물실험에서는 SKH-1 무모쥐에 일주일에 3번 UV를 조사하면서 5 % 생강나무 추출액을 국부적으로 도포하였다. 10주 후에는 각각의 무모쥐의 피부 모사판을 제작하여 관찰하였다. 광노화에 의한 주름형성에 미치는 영향을 알아보고자 UVB를 무모쥐의 피부조직에 조사한 후 생강나무 추출액을 도포하여 피부 상태를 관찰하였다. 모사판을 접사카메라를 이용하여 관찰한 결과 5 % 생강나무 추출액의 도포는 생강나무가 포함되지 않은 도포액을 도포한 대조군에 비해 UV에 의해 생성되는 주름 형성 억제에 영향을 주는 것으로 나타났다. 이러한 결과로 생강나무 추출액의 도포는 광노화에 의한 피부주름 생성을 억제하고 피부를 보호하는 효과가 있을 것으로 판단된다.

• 한국광학회지
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• 제20권2호
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• pp.110-117
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• 2009

본 논문은 광원 및 디스플레이 기기의 중요한 품질 지표 중 하나인 색특성 측정과 관련하여 대표적인 측정량인 CIE 1931(x, y) 색좌표, CIE 1960(u, v) 색좌표, 상관색온도(correlated color temperature, CCT), 분포온도(distribution temperature)에 대한 측정불확도 평가방법과 그 산출 예를 소개한다. 분광복사계를 사용하여 광원의 상대분광분포를 측정하고 이로부터 위의 색특성 측정량을 계산하는 경우에 대하여 표준소급체계를 소개하고, 상대분광분포의 불확도가 각 색특성 측정량의 불확도로 전파되는 과정을 파장간 상관관계를 고려한 행렬식을 이용하여 일관되게 유도한 후, CIE A 표준광원, LED 백색광, LCD 백색광에 대해 측정불확도 산출 예를 보였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.162-162
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• 2011

Nanometer-sized noble metals can trap and guide sunlight for enhanced absorption of light based on surface plasmon that is beneficial for generation of hot electron flows. A pulse of high kinetic energy electrons (1-3 eV), or hot electrons, in metals can be generated after surface exposure to external energy, such as in the absorption of light or in exothermic chemical processes. These energetic electrons are not at thermal equilibrium with the metal atoms. It is highly probable that the correlation between hot electron generation and surface plasmon can offer a new guide for energy conversion systems [1-3]. We show that hot electron flow is generated on the modified gold thin film (<10 nm) of metal-semiconductor (TiO2) Schottky diodes by photon absorption, which is amplified by localized surface plasmon resonance. The short-circuit photocurrent obtained with low energy photons (lower than bandgap of TiO2, ~3.1-3.2 eV) is consistent with Fowler's law, confirming the presence of hot electron flows. The morphology of the metal thin film was modified to a connected gold island structure after heating to 120, 160, 200, and 240$^{\circ}C$. These connected island structures exhibit both a significant increase in hot electron flow and a localized surface plasmon with the peak energy at 550-570 nm, which was separately characterized with UV-Vis [4]. The result indicates a strong correlation between the hot electron flow and localized surface plasmon resonance with possible application in hot electron based solar cells and photodetectors.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.92-92
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• 2012

Chalcopyrite-type Cu(In,Ga)Se2 (CIGS) is one of the most attractive compound semiconductor materials for thin film solar cells. Among various approaches to prepare the CIGS thin film, the powder process offers an extremely simple and materials-efficient method. Here, we present the mechano-chemical synthesis of CIGS compound powders and their use as an ink material for screen-printing. During the synthesis process, milling time and speed were varied in the range of 10~600 min and 100~300 rpm, respectively. Both phase evolution and powder characteristics were carefully monitored by X-ray diffraction (XRD) method, scanning electron microscope (SEM) observation, and particle size analysis by scanning mobility particle spectrometer (SMPS) and aerodynamic particle sizer (APS). We found the optimal milling condition as 200 rpm for 120 min but also found that a monolithic phase of CIGS powders without severe particle aggregation was difficult to be obtained by the mechano-chemical milling alone. Therefore, the optimized milling condition was combined with an adequate heat-treatment (300oC for 60 min) to provide the monolithic CIGS powder of a single phase with affordable particle characteristics for the preparation of CIGS thin film. The powder was used to prepare an ink for screen printing with which dense CIGS thin films were fabricated under the controlled selenization. The morphology and electrical properties of the thin films were analyzed by SEM images and hall measurement, respectively.

• 공업화학
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• 제27권5호
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• pp.467-471
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• 2016

새로운 전자 받개인 6,7-difluoro-2,3-dihexylquinoxaline을 이용하여 유기 태양 전지형 고분자를 개발하였다. Fluorene과 6,7-difluoro-2,3-dihexylquinoxaline으로 Suzuki polymerization방법을 이용하여 낮은 HOMO 에너지를 가지는 PFDTQxF 고분자를 합성하였다. 필름상태의 PFDTQxF은 368과 493 nm에서 두 개의 흡광도를 보였다. PFDTQxF의 HOMO와 LUMO 에너지는 각각 -5.55와 -3.91 eV을 나타내었다. PFDTQxF의 태양전지 소자는 0.47 V의 $V_{OC}$와 $4.48mA/cm^2$의 $J_{SC}$와 0.32의 FF를 가지고 있어 0.78%의 에너지 효율을 나타내었다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.213-216
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• 2011

The feasibility study must be conducted for construction of complex for generation of electric power such as items to get permission and grid connection etc. including wind resource to construct a complex for wind power generation. Since wind power can be used by converting only around 20~40% of energy coming in that kinetic energy of wind passes through blades and driving device into electric energy, when constructing a complex, the survey of wind resource takes up the most important part. Data logger used to measure this wind energy are expressed by calculating generally electromotive that is created from a sensor, variable-type, pulse-type signal to be proper for the actual value, and most data loggers have a type without considering geographical features. Besides, in the case of Met mast that is installed to survey the wind resource, since it is installed lower than the hub height of a wind power generator due to permission matters and the economic factors, the height of wind speed by utilizing Deacon equation is compensated to revise this. In this study, a device measuring wind speed was made by using algorithm that is possible to compensate the height of wind speed according to regional features and by applying Deacon equation, and the function of data storage through SD card or RS232 communication was added as well. Besides it's possible to check data more easily with a type of graph by using LCD touch screen for the convenience of users.

• 한국농림기상학회지
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• 제14권4호
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• pp.170-178
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• 2012

야생버섯의 인위적 재배를 위한 기초 기상환경을 평가하고자, 2002년부터 2004년까지 3년 동안 강원도 원주시 소초면 학곡리 치악산 국립공원 야영장 관리소 동쪽 150m에 위치한 정점 연구대상지에서 국지미기상과 야생버섯발생량을 조사하고 이들의 상관관계를 분석하였다. 야생버섯발생 조사는 6월부터 10월까지 월 1회씩 실시하였는데, 고온 다습한 7~8월에 야생버섯의 발생빈도가 높았으며 조사기간 중에서는 10월이 가장 낮았다. 그리고 발생빈도가 높은 B. citrina 등 9개종을 선발하여 야생버섯발생에 영향을 미치는 국지 미기상을 평가하였다. 야생버섯의 발생에 영향을 많이 주는 버섯발생 전 기상요소는 일사량으로 조사되었다. 다음으로 습도관련 기상요소인 상대습도, 강우량, 토양수분 순이었으며 기온과 지온의 영향이 가장 적은 것으로 분석되었다.