• Journal of Advanced Marine Engineering and Technology
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• 제36권7호
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• pp.876-884
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• 2012

The worldwide CPV(Concentrated Photo Voltaic) market has been increased rapidly due to the increase in large-scale PV(Photo Voltaic) plants which are situated in sun-rich areas with either a Mediterranean or equatorial-type climate. CPV systems are arguably some of the most important devices in the production of electricity within regions with a sun-rich climate, particularly those which benefit from abundant direct solar irradiation. We have developed a 500X CPV module with rated power of 170Wp. The CPV module must satisfy the constraint of having a sensitive tracking accuracy due to the limited tolerance of the acceptance angle in intrinsic optical design. In this study, the module's acceptance angle used was designed with a tolerance angle of ${\pm}1^{\circ}$ in the secondary optics design. In general, non-concentrated module type 2-axis trackers have a tolerance angle larger than ${\pm}1^{\circ}$ due to standard silicon-type modules which are insensitive to the tracking accuracy of the sun. They have a tolerance angle of ${\pm}2{\sim}4^{\circ}$, which fails to exert a significant influence on the performance of the module. This paper provides a study of an experimental variation of the efficiency of the CPV module in terms of its tracking accuracy. Also, the performance of the module is studied from the perspective of temperature and direct irradiation.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.315-324
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• 2001

Mechanochemical effects that occurred in the fine grinding process of quartz particles using planetary ball mill was investigated. Quartz particles have been frequently utilized for optical materials, semiconductor molding materials. We determined that grinding for a long time can be create amorphous structures from the crystalline quartz by Mechanochemical effects. But, to be produced nano-composite particles that the critical grinding time reached for composite materials in a short time. Henceforth, a qualitative estimation must be conducted on the filler for EMC(Epoxy molding compound) materials. It can be produced mechanochemically treated composite materials and also an integrated grinding efficiency considering of the nano-composite amorphous structured particles. The mechanochemical characteristics were evaluated based on particle morphology, size distribution, specific surface area, density and the amount of amorphous phase materials into the particle surface. The grinding operation in the planetary ball mill can be classified into three stages. During the first stage, initial particle size was reduced for the increase of specific surface area. In the second stage, the specific surface areas increased in spite of the increase in particle size. The final stage as a critical grinding stage, the ground quartz was considered mechanochemically treated particles as a nano- composite amorphous structured particles. The development of amorphous phase on the particle surface was evaluated by X-ray diffractometry, thermal gravity analysis and IR spectrometer. The amount of amorphous phase of particles ground for 2048 minutes was 85.3% and 88.2% by X-ray analysis and thermal gravity analysis, respectively.

• Bulletin of the Korean Chemical Society
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• 제26권3호
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• pp.440-446
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• 2005

A method is described for the determination of dibutyltin (DBT) in sediment by isotope dilution using liquid chromatography inductively-coupled plasma/mass spectrometry (LC-ICP/MS). To achieve the highest accuracy and precision, special attentions are paid in optimization and evaluation of overall processes of the analysis including extraction of analytes, characterization of the standards used for calibration and LC-ICP/MS conditions. An approach for characterization of natural abundance DBT standard has been developed by combining inductively-coupled plasma/optical emission spectrometry (ICP/OES) and LC-ICP/MS for the total Sn assay and the analysis of Sn species present as impurities, respectively. An excellent LC condition for separation of organotin species was found, which is suitable for simultaneous DBT and tributyltin (TBT) analysis as well as impurity analysis of DBT standards. Microwave extraction condition was also optimized for high efficiency while preventing species transformation. The present method determines the amount contents of DBT in sediments with expanded uncertainty of less than 5% and its result shows high degree of equivalence with reference values of an international inter-comparison and a certified reference material (CRM) within stated uncertainties.

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.559-565
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• 2011

The following noble series of statistical copolymers, poly[(2-(3-thienyl)ethanol n-butoxycarbonylmethylurethane)-co-3-hexylthiophene] (PURET-co-P3HT), were synthesized by the chemical dehydrogenation method using anhydrous $FeCl_3$. The structure and electro-optical properties of these copolymers were characterized using $^1H$-NMR, UV-visible spectroscopy, elemental analysis, GPC, DSC, TGA, photoluminescence (PL), and cyclic voltammetry (CV). The statistical copolymers, PURET-co-P3HT (1:0, 2:1, 1:1, 1:2, 1:3), were soluble in common organic solvents and easily spin coated onto indium-tin oxide (ITO) coated glass substrates. Hybrid bulk heterojunction photovoltaic cells with an ITO/G-PEDOT/PURET-co-P3HT:PCBM:Ag nanowires/$TiO_x$/Al configuration were fabricated, and the photovoltaic cells using PURET-co-P3HT (1:2) showed the best photovoltaic performance compared with those using PURET-co-P3HT (1:0, 2:1, 1:1, 1:3). The optimal hybrid bulk heterojunction photovoltaic cell exhibits a power conversion efficiency (PCE) of 1.58% ($V_{oc}$ = 0.82 V, $J_{sc}$ = 5.58, FF = 0.35) with PURET-co-P3HT (1:2) measured by using an AM 1.5 G irradiation (100 mW/$cm^2$) on an Oriel Xenon solar simulator (Oriel 300 W).

• 한국광학회지
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• 제5권3호
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• pp.386-393
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• 1994

XeCl 엑시머 레이저를 횡방향의 전자빔으로 여기하여 이의 출력특성을 조사하였다. 전자빔의 출력은 880kV, 21kA(70ns, FWHM)이며 전자빔의 전류밀도는 다이오드(A-K) 간격과 공진기 외부에 설치한 펄스자계코일(4.7kG)로 제어하였다. 레이저 매질에 주입되는 전자빔의 축적에너지는 35J(4기압)이다. 축적에너지는 Radcolor film의 감광면적과 압력상승법에 의해 측정한 가스매질의 상승압력으로부터 환산된 수치이며, 이 때의 여기체적은 $320cm^{3}$이었다. 레이저 가스의 혼합비율은 HCl/Xe/Ar=0.2/6.3/93.5%이고 총압력이 3기압일 때, 최대효율 1.7%를 얻었다. 이 때의 출력에너지, 특성에너지는 각각 0.52J, 1.7J/l이었다. 실험결과의 분석을 위해 컴퓨터 시뮬레이션코드를 완성하였다. 시뮬레이션 결과는 실험결과와 잘 부합하고 있음을 확인하였고 그 결과를 이용하여 XeCl의 형성채널, 완화채널, 308nm의 흡수채널을 이론적으로 설명하였다.

• 한국광학회지
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• 제28권2호
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• pp.53-58
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• 2017

본 논문은 집적화된 소형의 분광모듈 구현을 위한 나노회절격자의 설계 및 제작에 관한 연구이다. 제안된 평면 구조의 나노회절격자는 회절격자로부터 반사된 빛을 집광하기 위하여 비등간격의 구조로 설계되었으며, 400 nm에서 650 nm까지의 파장 대역폭에서 균등한 분해능을 가지도록 비대칭 V 홈 구조를 가지도록 설계되었다. 최적 설계된 나노회절격자를 저가, 대량 생산에 적합한 UV-NIL 공정을 통해 제작하기 위하여 FT-IR 흡수스펙트럼을 분석하였으며, 이를 통해 5 nm 이내의 치수 정밀도를 가진 고분자 나노회절격자를 제작 할 수 있었다. 제작된 고분자 기반 나노회절격자를 이용한 집적형 분광모듈은 250 nm의 파장 대역폭에서 각 첨두파장의 기준으로 5 nm의 균등한 파장 분해능을 확인하였으며, 이는 다양한 분광모듈의 적용분야에 적용될 것으로 기대된다.

• 한국광학회지
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• 제29권5호
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• pp.215-219
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• 2018

본 논문에서는 레이저 dewetting에 의해 형성된 은 나노입자들의 국소 표면플라즈몬 공명이 감응형 $TiO_2$ 태양전지의 전류밀도 및 효율 향상에 유용하게 이용될 수 있음을 보여준다. 전도성 유리기판 위에 증착된 은 박막을 펄스 레이저 조사에 의해 나노입자로 변환시킨 후 이 기판을 사용하여 감응형 $TiO_2$ 태양전지 셀을 제조한 결과, 은 나노입자를 포함하지 않은 대조군 셀에 비해 성능이 보다 향상됨을 확인하였다. 이는 은 나노입자들에 의한 국소 표면플라즈몬 공명 현상으로 인해 가시광 영역에서의 광수확이 증대되었기 때문으로 분석된다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
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• pp.117-121
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• 2006

Virgin bleached kraft pulp, CPO (computer printout) and white ledgers are main raw materials used in tissue mills. The utilization rate of recycled fibers and virgin pulp in South Korea tissue industry are 90% and 10%, respectively. To improve brightness of printing grades the use of 'fluorescent whitening agents (FWAs)' or 'optical brightening agents (OBAs)' has been increased. When recycling these papers for tissue production, it is unavoidable that FWAs contained in recycled papers flow into tissue production lines and remain in the products. And this draws great attention from the public. This study was carried out to develop a technology for the removal of fluorescent whitening agents from recycled fibers. Enzymatic removal of FWAs was evaluated as a method to remove FWAs from the recycled fiber. The ${\alpha}-amylase$ that degrades starched used for surface sizing of fine papers and contained substantial condition is needed to prevent the re-adsorption of FWAs on fibers. The temperature of pulp suspension was another important factor affecting on FWA removal. The higher the temperature, the greater the efficiency of removing FWAs was obtained. Optimum pH and temperature for the effective removal of FWAs were suggested to be pH 8.5 and $65^{\circ}C$, respectively. The enzymatic removal of FWAs showed a great synergistic effect when proper control in pH and temperature was made.

• 한국진공학회지
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• 제12권S1호
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• pp.95-99
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• 2003

We successfully grew InN/GaN single quantum well structures by metal-organic chemical vapor deposition and confirmed their formation by optical and structural measurements. We speculate that relatively high growth temperature ($730^{\circ}C$) of InN layer enhanced the formation of 2-dimensional quantum well structures, presumably due to high adatom mobility. As the growth interruption time increased, the PL emission efficiency from InN layer improved with peak position blue-shifted and the dislocation density decreased by one order of magnitude. The high resolution cross-sectional TEM images clearly showed that the InN layer thickness reduced from 2.5 nm (without GI) to about I urn (with 10 sec GI) and the InN/GaN interface became very flat with 10 sec GI. We suggest that decomposition and mass transport processes on InN during GI is responsible for these phenomena.

• 천문학회보
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• 제35권1호
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• pp.38.2-38.2
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• 2010

We report the current status of CQUEAN (Camera for QUasars in EArly uNiverse) development. CQUEAN is an optical CCD camera which uses a 1024*1024 pixel deep-depletion CCD. It has an enhanced QE than conventional CCD at wavelength band around 1${\mu}m$, thus it will be an efficient tool for observation of quasars at z > 7. It will be attached to the 2.1m telescope at McDonald Observatory, USA. A telescope interface containing a focal reducer is being designed to secure a larger field of view at the cassegrain focus of 2.1m telescope. Instrument control software will be written with python on linux platform. We are carrying out lab tests to investigate the characteristics of the system components in order to maximize the observational efficiency. Preliminary results of the tests will be presented. CQUEAN is expected to see the first light during summer season of 2010.