• 천문학회보
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• 제35권1호
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• pp.75.1-75.1
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• 2010

The first near-infrared (NIR) spectroscopic survey of SDSS-selected blue early-type galaxies (BEGs) has been conducted using the AKARI/IRC. The NIR spectra of 36 BEGs are successfully secured, which are well balanced in their SF/Seyfert/LINER type composition. For high signal-to-noise ratio, we stack the BEG spectra all and in bins of several properties: color, specific star formation rate and optically-determined spectral type. We estimate the NIR continuum slope and the 3.3 micron PAH emission equivalent width in the stacked BEG spectra, and compare them with those of SSP model galaxies and known ULIRGs. We first report the NIR spectral features of BEGs and discuss the nature of BEGs based on the comparison with other objects.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.111-114
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• 2002

We propose and fabricate a vertically integrated waveguide thermo-optic switch. It controls the optical path between two vertically stacked waveguide. As a first step, we fabricate polymeric waveguides. The measured propagation loss is ranged from 0.3 db/cm to 0.4 dB/cm at the wavelength of 1.55 $\mu\textrm{m}$. We fabricate the proposed vertically integrated waveguide thermo-optic switch to demonstrate its preliminary feasibility. The measured crosstalk is better than -10 db. The power consumption is about 500 mW. Further effort is necessary to improve its performance.

• E2M - 전기 전자와 첨단 소재
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• 제11권11호
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• pp.37-45
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• 1998

In this paper, present status of super high-efficiency tandem solar cells has been reviewed and key issues for realizing super high-efficiency have also been discussed. In addition, the terretrial R&D activities of tandem cells, in the New Sunshine Program of MITI(Ministry of International Trade and Industry) and NEDO(New Energy and Industrial Technology Development Organization) in Japan are reviewed briefly. The mechanical stacked 3-junction cells of monolithically grown InGaP/GaAs 2-junction cells and InGaAs cells have reached the highest efficiency achieved in Japan of 33.3% at 1-sun AM1.5. This paper also reports high-efficiency InGaP/GaAs 2-junction solar cells with a world-record efficiency of 26.9% at AM0, 28$^{\circ}C$ and radiation damage recovery phenomena of the tandem cell performance due to minority-carrier injection under light illumination or forward bias, which causes defect annealing in InGaP top cells. Future prospects for realizing super-high efficiency and low-cost tandem solar cells are also described.

• Journal of the Optical Society of Korea
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• 제10권3호
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• pp.124-129
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• 2006

We have developed a compact and cost-effective camera module on the basis of wafer-scale-replica processing. A multiple-layered structure of several aspheric lenses in a mobile-phone camera module is first assembled by bonding multiple glass-wafers on which 2-dimensional replica arrays of identical aspheric lenses are UV-embossed, followed by dicing the stacked wafers and packaging them with image sensor chips. This wafer-scale processing leads to at least 95% yield in mass-production, and potentially to a very slim phone with camera-module less than 2 mm in thickness. We have demonstrated a VGA camera module fabricated by the wafer-scale-replica processing with various UV-curable polymers having refractive indices between 1.4 and 1.6, and with three different glass-wafers of which both surfaces are embossed as aspheric lenses having $230{\mu}m$ sag-height and aspheric-coefficients of lens polynomials up to tenth-order. We have found that precise compensation in material shrinkage of the polymer materials is one of the most technical challenges, in orderto achieve a higher resolution in wafer-scaled lenses for mobile-phone camera modules.

• Journal of the Korean Wood Science and Technology
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• 제51권5호
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• pp.419-430
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• 2023

In this study, the floor impact sound insulation performance of Korean domestic Cross-Laminated Timber (CLT) slabs was evaluated according to their joint types, species and thicknesses in laboratory experiments. The sound insulation performance of the CLT has not been investigated before, thus, this study was conducted to quantify basic data on floor impact sound insulation performance of CLT slabs. 5-ply and 150 mm thick CLT panels made of 2 species, Larix kaempferi and Pinus densiflora, were used for the study. The CLT panels were assembled by 3 types of inter-panel joints to form floor slabs: spline, butt and half-lap. And the 150 mm thick Larix CLT slabs were stacked to the thicknesses of 300 mm and 450 mm. The heavy-weight floor impact sound insulation performance of the 150 mm CLT slabs were evaluated to be 70 dB for the Larix slabs and 71.6 dB for the Pinus slabs, and the light-weight floor impact sound insulation performance, 78.3 dB and 79.6 dB, respectively. No significant difference in the sound insulation performance was found between the slabs of the 2 species or among the 3 types of joints. The reduction of 1 dB in the heavy-weight floor impact sound and 1.6 dB in the light-weight floor impact sound per 30 mm increase in thickness were confirmed through the experiments. This study can be viewed as the basic research for the evaluation of floor impact sound insulation performance of CLT.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.371-374
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• 2005

This paper presents the design and fabrication of a cost effective and broad band 8$\times$8 stacked patch array antenna which are backed by a metal cavity operating at 400Hz based on 4 layers LTCC technology. Gain of antenna can be enhanced by using a metal cavity, which can be easily implemented by using LTCC substrates and vias. The broadband performance can be obtained by varying the dimension of patch and the number of layers. Furthermore, to keep the feeding network as smal1 as possible and reduce radiation from feeding network a mirrored patch orientation and embedded micro strip line are adopted, The fabricated antenna is $40\times45\times0.4$ $mm^3$in size. It shows gain 20.4dBi, beam width 10.7deg and impedance bandwidth of l0dE return loss 3.35GHz (40.9$\sim$44.25 GHz), which is about 8% of a center frequency.

• Steel and Composite Structures
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• 제48권3호
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• pp.321-333
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• 2023

This paper proposes a comprehensive investigation on lateral stiffness of corner-supported steel modular frame using splice connection. A full-scale modular frame with two stacked steel modules under lateral load is tested. Ductile pattern in the transfer of lateral load is found in the final failure mode. Two types of lateral stiffness, including tangent stiffness and secant stiffness, are defined from the load-displacement due to the observed nonlinearity. The difference between these two types of stiffness is found around 20%. The comparisons between the experimental lateral stiffness and the predictions of classical methods are also conducted. The D-value method using hypothesis of independent case is a conservative option for predicting lateral stiffness, which is more recommended than method of contraflexural bending moment. Analyses on two classical short-rod models, including fix-rod model and pin-rod model, are further conducted. Results indicate that fix-rod model is more recommended than pin-rod model to simplify splice connection for simulation on lateral stiffness of modular frame in elastic design stage.

• 대한토목학회논문집
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• 제44권2호
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• pp.183-190
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• 2024

폴리우레탄(PU) 폼과 같은 가연성 고분자 건축자재의 화재 안전성을 개선하기 위한 새로운 접근의 나노코팅 기술이 개발되었다. 산화 그래핀 (Graphene oxide, GO)과 같은 2차원 소재는 용액상에서 자기 정렬 및 점탄성적 특성을 보이는 액정성(Liquid Crystalline properties, LC)을 나타내며, 이를 이용하면 특정 농도 범위에서 3차원의 다공성 폼을 포함한 다양한 표면에 균일한 코팅이 가능하다. 또한, GO의 액정성을 이용하여 기능성 복합소재의 나노코팅을 위한 골격 구조체(Scaffold)를 형성할 수 있으며, 여기에 도파민(Dopamine)과 같은 무독성의 항산화성 저분자를 도입 후 폴리도파민(polydopamine, PDA)로의 중합을 유도하여 고난연성의 폴리도파민/산화그래핀 (PDA/GO) 나노복합체 코팅층을 형성할 수 있다. 또한 최종적으로 형성된 PDA/GO 코팅은 GO의 2차원 판상구조로 인하여 균일하게 적층된 나노시트 구조로 안정화되며, 이러한 구조적 특성으로 인하여 가스상의 유해 연소생성물의 발생과 확산을 효과적으로 저감할 수 있는 가스 차폐 효과도 유도할 수 있다. 이러한 2차원 소재의 액정성을 활용한 난연성 나노복합소재 코팅 기술은 다양한 유형의 고분자 건축 자재의 화재 안전성을 효과적으로 개선할 수 있는 친환경적이고 새로운 기술적 접근방식이 될 수 있다.

• Bulletin of the Korean Chemical Society
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• 제26권11호
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• pp.1728-1734
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• 2005

The interactions of Cu(II)-meso-Tetrakis(n-N-methylpyridiniumyl)porphyrin (n = 2,3,4), respectively referred to as o-, m- and p-CuTMPyP, and DNA, poly$[d(A-T)_2]$ and poly$[d(G-C)_2]$ were investigated by circular and linear dichroism (CD and LD). In the o-CuTMPyP case, in which the rotation of the pyridinium ring is prevented, the shape of the CD spectrum when associated to DNA and poly$[d(A-T)_2]$ resembles and is characterized by a positive band at a low drug to DNA concentration ratio (R ratio) and is bisignate at a high R ratio. The former CD spectrum shape has been attributed to porphyrin that is bound monomerically outside of DNA while the latter can be attributed to those that are stacked. When o-CuTMPyP is bound to poly$[d(G-C)_2]$, the excitonic CD appeared at a relatively high R ratio. In contrast, a characteristic negative CD band in the Soret region was apparent for both m- and p-CuTMPyP when bound to DNA and poly$[d(G-C)_2]$ at the low R ratios, indicating that the porphyrin molecule intercalates. However, the DNA is bent near the intercalation site and the plane of the porphyrin molecule tilts relative to the DNA helix axis, as judged by the magnitude of the reduced LD. Various stacking patterns were identified by the shape of the CD spectrum for m- and p-CuTMPyP when bound to poly$[d(A-T)_2]$. Three species for the former complex and two for the latter complex were found which may reflect the extent of the stacking.

• 한국컴퓨터정보학회논문지
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• 제16권9호
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• pp.1-10
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• 2011

동작 주파수의 증가는 싱글코어 프로세서의 성능을 크게 향상시키는 반면 전력 소모 증가와 높은 온도로 인한 신뢰성 저하 문제를 유발하고 있다. 최근에는 싱글코어 프로세서의 한계점을 극복하기 위한 대안으로 멀티코어 프로세서가 주로 사용되고 있다. 하지만, 멀티코어 프로세서를 2차원 구조로 설계하는 경우에는 내부 연결망에서의 전송 지연 현상으로 인해 프로세서의 성능 향상이 제약을 받고 있다. 내부 연결망에서의 전송 지연을 줄이기 위한 방안으로 멀티코어 프로세서를 3차원 구조로 설계하는 연구가 최근 큰 주목을 받고 있다. 2차원 구조 멀티코어 프로세서와 비교하여 3차원 구조 멀티코어 프로세서는 성능 향상과 전력 소모 감소의 장점을 지닌 반면, 높은 전력 밀도로 인해 발생된 발열 문제가 프로세서의 신뢰성을 위협하는 문제가 되고 있다. 3차원 멀티코어 프로세서에서 발생되는 발열 문제에 대한 상세한 분석이 제공된다면, 프로세서의 신뢰성을 확보하기 위한 연구 진행에 큰 도움이 될 것으로 기대된다. 그러므로 본 논문에서는 3차원 멀티코어 프로세서의 온도에 밀접하게 연관된 요소인 작업량, 방열판과의 거리, 그리고 적층되는 다이의 개수와 온도 사이의 관계를 자세히 살펴보고 높은 온도가 프로세서의 성능에 미치는 영향 또한 분석하고자 한다. 특히, 2차원 구조 멀티코어 프로세서와 3차원 구조 멀티코어 프로세서에서의 온도 문제를 함께 분석함으로써, 온도 측면에서 효율적인 프로세서 설계를 위한 가이드라인을 제시하고자 한다.