• 한국태양에너지학회 논문집
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• 제40권5호
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• pp.23-34
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• 2020

Concentrator photovoltaic (CPV) system consists of high-quality complex optical elements, mechanical devices, and electronics components and can have the advantages of high integration and high-efficiency energy sources. III-V compound semiconductor cells have proven performance based on high reliability in the aerospace field, but have characteristics that require absolute support of the balance of systems (BOS) such as solar position trackers, receivers with heat sinks, and housing instruments. To determine the optimum parameters of secondary optical elements (SOEs) design for CPV systems, we designed three types of CPV modules, classified as non-SOEs type, reflective mirror type, and CPC lens type. We measured the I-V and P-V characteristics of the prototype CPV modules with the angle of inclination varying from 0° to 12° and with a 500-magnification Fresnel lens. The experimental results assumed misalignment of the solar position tracker or module design of pinpoint accuracy. As a result, at the 0° tilt angle, the CPC lens produced lower power due to the quartz transmittance ratio compared to that by other SOEs. However, for tilt angles greater than 3°, the CPC lens type module achieved high efficiency and stability. This study is expected to help design high-performance CPV systems.

• Journal of Astronomy and Space Sciences
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• 제34권2호
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• pp.75-82
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• 2017

High-resolution spectroscopic observations of the eclipsing binary system RR Lyn were made using the 1.8 m telescope at the Bohuynsan Optical Astronomical Observatory in Korea. The spectral resolving power was R = 82,000, with a signal to noise ratio of S/N > 150. We found the effective temperatures and surface gravities of the primary and secondary components to be equal to $T_{eff}$ = 7,920 & 7,210 K and log(g) = 3.80 & 4.16, respectively. The abundances of 34 and 17 different chemical elements were found in the atmospheric components. Correlations between the derived abundances with condensation temperatures and the second ionization potentials of these elements are discussed. The primary component is a typical metallic line star with the abundances of light and iron group elements close to solar values, while elements with atomic numbers Z > 30 are overabundant by 0.5-1.5 dex with respect to solar values. The secondary component is a ${\lambda}$ Boo type star. In this type of stars, CNO abundances are close to solar values, while the abundance pattern shows a negative correlation with condensation temperatures.

• 한국태양에너지학회 논문집
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• 제34권4호
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• pp.39-44
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• 2014

The elemental composition of electro-deposited black Cr solar selective coatings before and after heating in air by using secondary ion mass spectrometry (SIMS) was investigated for optical property analysis. In addition, black Cr selective coating exposed by solar radiation for 5 months was compared with heated sample. SIMS investigation shows that $OH^+$ bearing ions were related to a near surface region of CrOH and CrO compound. The optical degradation of this coating after heating at $500^{\circ}C$ reveals that diffusion of the Cu and Ni elements in substrate material, the chemical interactions adjacent to the interface, and the interface width broadening.

• 천문학논총
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• 제20권1호
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• pp.143-149
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• 2005

KASI (Korea Astronomy and Space Science Institute) is developing the near-infrared camera system named KASINICS (KASI Near-Infrared Camera System) which will be installed at the 60cm f/13.5 Ritchey-Chretien telescope of the Sobaeksan Optical Astronomy Observatory (SOAO). The camera system is optimized for JHKL bands and has a 6 arcmin FOV. The optical system consists of two spherical mirrors and a 8-position filter wheel. With the exception for the dewar window, all optical elements are cooled inside cryogenic dewar. Since the Offner system is adopted to prevent thermal noises from outside of the telescope primary mirror, the secondary mirror of the Offner system acts as a cold Lyot stop. The optical performance does not change by temperature variations because the Aluminum mirrors contract and expand homogeneously with its mount. We finished the design and fabrication of the optical parts and are now aligning the optical system. We plan to have a test observation on 2006 January.

• Nuclear Engineering and Technology
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• 제44권5호
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• pp.491-500
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• 2012

The dissimilar metal joints welded between Ni-based alloy, Alloy 690 and low alloy steel, A533 Gr. B with Alloy 152 filler metal were characterized by using optical microscope, scanning electron microscope, transmission electron microscope, secondary ion mass spectrometry and 3-dimensional atom probe tomography. It was found that in the weld root region, the weld was divided into several regions including unmixed zone in Ni-base alloy, fusion boundary, and heat-affected zone in the low alloy steel. The result of nanostructural and nanochemical analyses in this study showed the non-homogeneous distribution of elements with higher Fe but lower Mn, Ni and Cr in A533 Gr. B compared with Alloy 152, and the precipitation of carbides near the fusion boundary.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.367-367
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• 2011

CIGS solar cell with copper, indium, gallium and selenium is a second generation solar cells for the lowering of the manufacturing cost. The relative ratio of the four elements is one of the most important measurement issues because the photovoltaic property of CIGS solar cell depends on the crystalline structure of the CIGS layer. However, there is no useful analysis method for the composition of the CIGS layer. Recently, AES depth profiling analysis of CIGS films has been studied with a reference material certified by inductively coupled plasma optical emission spectroscopy. However, there are some problems in AES depth profiling analysis of CIGS films. In this study, the in-depth profiling analysis was investigated by secondary ion mass spectrometry (SIMS) depth profiling analysis. We will present the compositional depth profiling of CIGS films by SIMS and its applications for the development of CIGS solar cells with high efficiency.

• 천문학회보
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• 제36권2호
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• pp.141.2-141.2
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• 2011

We present physical parameters of the detached eclipsing binary KIC3858884, which has a d-Scuti type pulsating secondary component. To derive orbital elements from radial-velocity curve, high-resolution Echelle spectra were obtained at the Bohyunsan Optical Astronomy Observatory in Korea. The BOES spectra and Kepler photometric data were analyzed with JKTEBOP and Wilson-Devinney model for eclipsing light-curve synthesis and Period04 for pulsation frequency analysis. After the iterative curve fitting, we determined physical parameters of KIC3858884 as $M_1=2.02{\pm}0.23M_{\odot}$, $M_2=2.02{\pm}0.16M_{\odot}$, $R_1=3.61{\pm}0.12R_{\odot}$, $R_2=2.84{\pm}0.10R_{\odot}$, respectively.

• Journal of Astronomy and Space Sciences
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• 제20권4호
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• pp.239-248
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• 2003

2001년 3월부터 5월까지 총 11일간 소백산천문대의 61cm 망원경과 VR 필터를 사용하여 근접촉쌍성 AX Dra의 광도곡선을 완성하였다. 우리의 관측으로부터 7개(주극심 3개, 부극심 4개)의 새로운 극심시각과 최근의 관측자료에 맞는 광도요소를 결정하였다. Wilson-Devinney 쌍성모델과 q-search방법을 이용하여, 우리의 VR광도곡선을 다양한 로쉬모형과 질량비에 대하여 분석하였다. 그 결과, 우리는 식쌍성 AX Dra가 분리형이거나 반성은 로쉬로브를 채우고 주성은 거의 채운 준분리형인 FO Vir형 근접촉쌍성계임을 알아내었다. 또한, FO Vir형 근접촉쌍성계의 통계적인 연구(Shaw 1994)와 달리, 우리의 VR광도곡선은 모두 같은 형태의 O'Connell효과를 보이고 있으며 그 크기는 약 $0^{m}.008$정도이다.

• Current Photovoltaic Research
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• 제5권4호
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• pp.140-144
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• 2017

$CuSbS_2$ (CAS) and $CuSbSe_2$ (CASe) nanocrystals (NCs), which consist of earth-abundant elements, were synthesized by a mechanochemical method. Elemental precursors such as copper, antimony, sulfur, and selenium were used without adding any organic solvents or additives. The NCs were synthesized by milling for a few hours. The sudden phase changes occurred by self-ignition and propagation, as previously observed in other mechanochemical synthetic processes. The XRD, Raman, and TEM analysis were carried out to determine the crystallinity and secondary phase of the as-synthesized CAS and CASe NCs, confirming the phase-pure synthesis of CAS and CASe. Optical properties were investigated by UV-Vis spectroscopy and it was observed that the band gap energies were about 1.1 and 1.5 eV, respectively for CAS and CASe, suggesting the potential for the use as solar cell materials. The NC colloids dispersed in anhydrous ethanol were prepared and coated on Mo substrates by a facile doctor-blade method. The investigation on the solar cell properties of the as-synthesized materials is underway.

• Journal of Astronomy and Space Sciences
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• 제16권2호
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• pp.227-240
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• 1999

소백산천문대의 61cm 망원경을 이용하여 1996년 5월 12일과 1999년 5월 5일부터 6월 8일까지 총 8일 밤 동안 W UMa 형 접촉쌍성 BV Dra의 CCD 측광광측을 수행하여 이 쌍성계의 BV R광도 곡선을 완성하였다. 우리의 관측으로부터 9개의 새로운 극심시간 (제1 극심: 5개, 제2 극심: 4개)을 산출하였고, 1999년 이후에 관측된 극심시간으로부터 새로운 광도요소를 결정하였다. 우리의 BV R광도곡선과 Batten & Lu (1986)의 시선속도곡선을 Wilson-Devinney 쌍성모델의 접촉모드 (Mode 3)에 적용하여 BV Dra의 측광 및 분광학적 해를 구하였다. 이 분석에서 광도곡선 비대칭의 원인을 흑점에 의한 것으로 가정하여 흑점이 있는 경우와 없는 경우로 나누어 1999년 광도곡선 해를 산출하였다. 그 결과, 우리는 이전의 연구자들에 의해 보고되지 않은 광도곡선 비대칭을 반성표면 위에 hot spot가 존재하고, 주성표면 위에 cool spot가 존재해서 일어난다고 해석하였다. 광도곡선과 시선속도곡선의 분석에 의해 산출한 BV Dra의 절대 물리량은 $M_1=0.40M_{odot}$, $M_2=1.01M_{odot}$, $R_1=0.72R_{odot}$, $R_2=0.40R_{odot}$ 이다. 이 절대 물리량을 이용하여 질량-반경도를 살펴본 결과, 질량이 작은 주성이 종년 주계열 (TAMS)근처에 있고, 질량이 큰 반성이 영년주계열 (ZAMS)근처에 위치하고 있다. 이는 질량-반경도에서 다른 W형 W UMa쌍성계의 위치와 매우 비슷하다.