• 한국전자파학회논문지
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• 제21권11호
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• pp.1229-1234
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• 2010

차세대 이동 통신에서는 고품질, 고속 통신의 멀티미디어 서비스를 요구한다. 이러한 서비스를 만족시키기 위해서는 강력한 오류 정정 기법이 사용된다. ARQ(Auto Repeat Request) 기법은 전송 효율적인 측면, 그리고 FEC(Forward Error Correction) 기법은 높은 신뢰도면에서 취약한 단점을 가지고 있다. 이러한 단점을 서로 보완한 H-ARQ(Hybrid Auto Repeat Request) 시스템이 현재 연구 중에 있다. 따라서 본 논문에서는 cross layer를 이용한 H-ARQ 시스템을 분석하였다. Cross layer coding 기법과 H-ARQ type, 채널 환경에 따라 적합한 H-ARQ 방식을 BER 성능과 전송 효율 분석을 통해 제안한다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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• pp.251-257
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• 1998

Spherical space frame structure with triangular network pattern, which has the various characteristics for the mechanic property, a funtional property, an aesthetic property and so on, has often been used as one of the most efficient space structures. It is expected that this type will be used widely in large-span structural roofs. But because this structure is made of network by combination of line elements there me many nodes therefore, the structure behavior is very complicated and there can be an overall collapse of structure by buckling phenomenon if the external force reaches a limitation. This kind of buckling is due to geometric shape, network pattern, the number of layer and so on, of structure. Therefore spherical space frame with triangle network pattern have attracted many designers and researchers attention all over the world. The number of layer of space frame is divided in to the simgle, double, multi layer. That is important element which is considered deeply in the beginning of structural design. The buckling characteristics of single-layer model and double-layer model for the spherical space frame structure with triangular network pattern are evaluated and the buckling loads of these types are compared with investigation their structural efficiency in this study.

• 한국수소및신에너지학회논문집
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• 제29권6호
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• pp.627-634
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• 2018

Gallium-based liquid metal, e.g., eutectic gallium-indium (EGaIn), is highly attractive as an electrode material for flexible and stretchable devices. On the liquid metal, oxide layer is spontaneously formed, which has a wide band-gap, and therefore is electrically insulating. In this paper, we fabricate a capacitor based on eutectic gallium-indium (EGaIn) liquid metal and investigate its cyclic voltammetry (CV) behavior. The EGaIn capacitor is composed of two EGaIn electrodes and electrolyte. CV curves reveal that the EGaIn capacitor shows the behavior of electric double-layer capacitors (EDLC), where the oxide layers on the EGaIn electrodes serves as the dielectric layer of EDLC. The oxide thicker than the spontaneously-formed native oxide decreases the capacitance of the EGaIn capacitor, due to increased voltage loss across the oxide layer. The EGaIn capacitor without oxide layer exhibits unstable CV curves during the repeated cycles, where self-repair characteristic of the oxide was observed. Finally, the electrolyte concentration is optimized by comparing the CV curves at various electrolyte concentrations.

• Bulletin of the Korean Chemical Society
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• 제30권4호
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• pp.869-872
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• 2009

Double-doped magnetic particles that incorporated magnetites into both the surface and inside the silica cores were fabricated via the sol-gel reaction of citrate-stabilized magnetites with silicon alkoxide. Double-doped magnetic particles were easily fabricated and exhibited an higher magnetism in comparison to the singledoped magnetic particles that were prepared by the erosion of surface-deposited magneties from double-doped magentic particles. Thin gold layer was formed over magnetic silica nanospheres via nanoseed-mediated growth of gold clusters. The plasmon-derived absorption bands of double-doped magnetic silica-gold nanoshells were more broadened and shifted down by ca. 20 nm as compared to those of single-doped magnetic silicagold nanoshells, which were attributed to not only the surface scattering of incident light due to relatively rough surafce morphology, but also heterogeneous permittivity of dielectric cores due to surface-deposited magnetites.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.405-405
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• 2011

실리콘 질화막(SiNx : H)는 결정질 실리콘 태양전지 제작 공정에서 ARC (Anti Reflection Coating)과 표면 패시베이션의 역할로써 많이 사용되었지만, layer 자체의 quality가 좋지 않기 때문에 최근에는 SiNx/SiO2 이중 layer로 passivation layer를 형성하고 있다. SiO2 layer는 Si substrate를 소스로 하여 성장시키기 때문에 막의 질이 우수하기는 하지만, 막 성장을 위해서 Furnace를 이용해야 하기 때문에, 공정 시간과 공정 비용을 증가시키는 단점이 있다. 본 연구에서는 SiO2 layer를 Furnace가 아닌, 질산(HNO3)을 이용하여SiNx/Thin SiO2 passivation layer 제작하였다. 실험에서는 SiO2 성장을 위해서 질산 용액에 p-type wafer를 dipping하여 시간대 별, SiO2 막의 두께를 관찰하였고, passivation의 효과를 확인하기 위해 lifetime을 측정하였다. 그 결과 SiNx/SiO2 이중 passivation layer는 SiNx 단일 막으로 passivation을 하였을 때보다, lifetime이 10 us 상승했고, 셀 제작시 효율은 약 1.1%, Fill Factor는 약 4% 정도 증가한 것을 확인할 수 있었다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.251-254
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• 2002

The technique of high speed machining is widely studied in machining field. In this study, TiAIN single-layered and TiAIN/TiN double-layered coatings were applied to end-mill by an arc ion plating technique. Their performances were comparatively studied about cutting force, tool wear, tool life and surface roughness of workpiece under high speed cutting conditions. The TiAIN single-layer coated tool showed higher wear-resistance due to its higher hardness, while the TiAIN/TiN double-layer coated tool showed better performance for high metal removal, i.e., high fled per tooth condition due to its higher toughness. The surface roughness of the workpiece was not influenced by the wear amount of coated tools.

• Transactions on Electrical and Electronic Materials
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• 제12권5호
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• pp.197-199
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• 2011

In this paper, the bottom-gate thin-film transistors (TFTs) were fabricated with an amorphous/microcrystalline Si double layer (DL) as an active layer and the variations of the electrical characteristics were investigated according to the DC bias stresses. Since the fabrication process of DL TFTs was identical to that of the conventional amorphous Si (a-Si) TFTs, it creates no additional manufacturing cost. Moreover, the amorphous/microcrystalline Si DL could possibly improve stability and mass production efficiency. Although the field effect mobility of the typical DL TFTs is similar to that of a-Si TFTs, the DL TFTs had a higher reliability with respect to the direct current (DC) bias stresses.

• 연구논문집
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• 통권31호
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• pp.127-133
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• 2001

In chromium electrodeposition, crack is inevitably accompanied by chromium layer. Behavior of crack formation and crack density were different from the plating conditions such as current density, temperature, waveform of applied current and so on. And cracks have an influence on the corrosion resistance of chromium deposit, because corrosion occurs through the network of cracks between deposit and substrate. Therefore, many researches have been achieved in order to remove the cracks in chromium deposit. Formation of double layers, Cr/Cr and Ni/Cr were investigated to increase corrosion resistance of chromium deposit in this study. As pretreatment prior to outer chromium coating, acid pickling and current control method were examined. Cracks in cross-section of each sample were observed with SEM and CASS(Copper modified acetic acid salt spray) test was performed to evaluate corrosion resistance. It was found that corrosion resistance of Cr/Cr and Ni/Cr double layers were superior to Cr or Ni single layer from the results of CASS test.

• 한국진공학회지
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• 제4권S2호
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• pp.40-48
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• 1995

$TiB_2$-TiN double-layer coating have been prepared by ion beam enhanced deposition. AES, XRD, TEM and HRTEM were employed to characterize the $TiB_2$ layer. The microhardness of the coatings was evaluated by an ultra low-load microhardness indenter system, and the tribological behavior was examined by a ball-on-disc tribology wear tester. It was found that in a single titanium diboride layer, the composition is uniform along the depth of the film, and it is mainly composed of nanocrystalline $TiB_2$ with hexagonal structure, which resulted from the ion bombardment during the film growth. The hardness of the $TiB_2$ films increases with increasing ion energy, and approaches a maximum value of the $TiB_2$ films increases with increasing ion energy, and approaches a maximum value of 39 Gpa at ion energy of 85 keV. The tribological property of the TiB2 films is also improved by higher energy of 85keV. The tribological property of the $TiB_2$ films is also improved by higher energy ion beam bombardment. There is no major disparity in the mechanical properties of double-layer $TiB_2$/TiN coatings and TiN/$TiB_2$ coatings. Both show an improved wear resistance compared with single-layer $TiB_2$ films. The adhesion of double-layer coatings is also superior to that of single-layer films.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.355-356
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• 2013