• Journal of the Optical Society of Korea
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• 제19권1호
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• pp.102-111
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• 2015

This paper proposes an algorithm for recovering the colors of objects from multiple near-infrared (near-IR) images. The International Commission on Illumination (CIE) color coordinates of objects are recovered from a series of gray images captured under multiple spectral near-IR illuminations using polynomial regression. The feasibility of the proposed algorithm is tested experimentally by using 24 color patches of the Color Rendition Chart. The experimental apparatus is composed of a monochrome digital camera without an IR cut-off filter and a custom-designed LED illuminator emitting multiple spectral near-IR illuminations, with peak wavelengths near the red edge of the visible band, namely at 700, 740, 780, and 860 nm. The average color difference between the original and the recovered colors for all 24 patches was found to be 11.1. However, if some particular patches with high value are disregarded, the average color difference is reduced to 4.2, and this value is within the acceptability tolerance for complex image on the display.

• 항공우주산업기술동향
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• 제8권1호
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• pp.3-11
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• 2010

세계적인 불경기에도 불구하고 세계 우주시장은 전년대비 11% 증가하여 2009년 최대치인 1,609억불에 도달하였다. 세계 각국의 우주 분야 투자도 전년대비 10% 증가한 680억불에 이르렀다. 반면 우리나라의 우주분야 예산은 2009년 2억 1,700억불로 전년대비 24% 감소하였다. 나로호 개발이 완료됨에 따라 개발 주기에 따른 예산 감소의 영향으로 분석된다. 우주시장 역시 불경기에 따른 위성 핸드폰 등의 수출 감소로 전년 대비 3% 감소한 8,644억 원으로 조사되었다. 본 논문에서는 세계 각국 및 우리나라의 우주분야 투자와 우주시장 현황을 정리하였고, 우리나라 예산정책에 관한 시사점을 제고해보았다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.734-739
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• 2003

Many types of smart materials and control laws are available to actively adjust the structure from various external disturbances. Usually, a certain type of control laws to activate a specific smart material is well established, but the effectiveness of the control scheme is limited by the choice of the smart materials and the responses of the structure. ER fluid is adequate to provide relatively large control force, on the other hand, the PZT patches are suitable to provide small but arbitrary control forces at any point along the structure. It was found that active vibration control mechanism using ER fluid failed to suppress the excitation off the resonant frequency with changed structural characteristics along the frequency response function of the closed loop of the control system. To compensate this additional peak of the closed loop system, PPF control using PZT as an actuator is added to construct a hybrid controller.

• Toxicological Research
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• 제19권1호
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• pp.67-72
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• 2003

Cholestatic liver injury results from the accumulation of toxic bile salts within the liver. The aim of the present study is to elucidate the changes in expression and cellular localization of apoptosis related proteins in the liver of bile duct-ligated (BDL) rat. Extrahepatic cholestasis was induced by double ligation of the common bile duct and cut between the ligatures. Animals were sacrificed at day 3 and at week 1, 2, 4, 6, and 8 after BDL. The number of TUNEL positive cells was increased significantly after 3 days of BDL, decreased over 2 weeks and remained constant thereafter. Fas expression was not changed and activation of caspase 8 did not occur. Fas immunoreactivity was exclusively observed in the cytoplasm of hepatocytes, indicating that Fas expressed in rat hepatocytes is a soluble form. Hepatocyte apoptosis was associated with Bax expression, which showed a peak at day 3 and decreased over time gradually. Immnunostaining of Bax was observed in hepatocytes and bile duct epithelial cells (BEC) of control and BDL rats. Bcl-2 was increased over time in BDL rats. These results suggest that apoptosis of hepatocytes in BDL rats is independent of Fas and controlled by Bax expression.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권11호
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• pp.561-568
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• 2005

This paper proposes a method that distributes the load power and stores the regenerated energy for a hoist-load system using the supercapacitor, an energy storage device. The crane, which is a representative hoist-load system, operates in two modes. The first is the hoist-up mode in which the load container is lifted up: the maximum power is required at the end of acceleration. The second is the hoist-down mode in which the load container is lifted down; the regenerated energy is wasted by the resistor In this paper, the supercapacitor stores the regenerated energy in the hoist-down operation and supplies the peak power demand in the hoist-up operation. The same structure as the commercially available three-phase inverter is proposed as a bidirectional do-dc converter to charge and discharge the supercapacitor. A power control algorithm is proposed to optimize the load sharing between the generator and the supercapacitor. Using the proposed method, it is effected that the generator size can be cut down to one third of the original one; it leads to the reduction of the fuel consumption, noise and air pollution. Simulation and experimental results verify the effectiveness of the Proposed method.

• 한국초전도ㆍ저온공학회논문지
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• 제16권3호
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• pp.7-9
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• 2014

Single-crystal like $MgB_2$ thin film was grown on (000l) $Al_2O_3$ substrate by using hybrid physical-chemical vapor deposition (HPCVD) system. Single crystal properties were studied by X-ray diffraction (XRD) and the full width at half maximum (FWHM) of the (0001) $MgB_2$ peak is $15^{\circ}$, which is very close to that has been reported for $MgB_2$ single-crystal. It indicates that the crystalline quality of thin film is good. Temperature dependence on resistivity was investigated by physical property measurement system (PPMS) in various applied fields from 0 to 9 T. The upper critical field ($H_{c2}$) and irreversibility field ($H_{irr}$) were determined from PPMS data, and the estimated values are comparable with that of $MgB_2$ single-crystals. The thin film shows a high critical temperature ($T_c$) of 40.4 K with a sharp superconducting transition width of 0.2 K, and a high residual resistivity ratio (RRR=21), it reflects that $MgB_2$ thin film has a pure phase structure.

• International Journal of Precision Engineering and Manufacturing
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• 제9권4호
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• pp.74-78
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• 2008

High-speed tool steels are extensively used in tooling industries for manufacturing cutting tools, forming tools, and rolls. Electrical discharge machining (EDM) has been found to be an effective process for machining these extremely hard and difficult-to-cut materials. Extensive research has been conducted to identify the optimum machining parameters for EDM with different tool steels. This paper presents a fundamental study of the surface characteristics of SKH-51 tool steel machined by micro-EDM, with particular focus on obtaining a better surface finish. An RC pulse generator was used to obtain a better surface finish as it produces fine discharge craters. The main operating parameters studied were the gap voltage and the capacitance while the resistance and other gap control parameters were kept constant. A negative tungsten electrode was used in this study. The micro-EDM performance was analyzed by atomic force microscopy to determine the average surface roughness and the distance between the highest peak and lowest valley. The topography of the machined surface was observed using a scanning electron microscope and a digital optical microscope.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 추계 학술논문 발표대회
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• pp.79-80
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• 2017

This study examined the effect that the amorphous metallic fibers had on the static mechanical properties and the impact resistance of cement composites to those of hooked steel fibers. The hooked steel fiber exhibited pull-out from the matrix after the peak flexural stress was attained, while the amorphous metallic fiber was not pulled out from the matrix, but was instead cut off. In terms of impact resistance, the amorphous metallic fiber reinforced cement composite was found to be more effective at resisting cracking than the hooked steel fiber reinforced cement composite. Therefore, amorphous metallic fiber should be used in fiber reinforced cement composite materials, and for structural materials, and for protection panels.

• 한국통신학회논문지
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• 제41권6호
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• pp.678-680
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• 2016

에너지 환경의 변화로 인해 가정 내 태양광 도입이 활발히 이루어지고 있다. 더불어 에너지 저장 시스템도 함께 활용되어 보다 유연한 에너지 관리가 이루어지고 있다. 태양광으로 생산된 전력을 보다 효과적으로 사용하여 피크 저감 및 가격을 고려한 전력소비를 이룰 수 있다. 본 연구에서는 에너지 저장 시스템을 홈 네트워크로 연동하여 홈 에너지관리 시스템의 구성요소로 이루기 위해 SEP(Smart Energy Profile)을 개발하였다. 에너지 저장 시스템에서 갖추고 있는 기능을 정의하고 표준 기반 프로토콜을 개발하여 제품간 호환을 이룰 수 있도록 하였다. 향후 주택에 에너지관리시스템 도입을 위해 상호운용성 확보는 매우 중요한 과제이며 이를 앞당길 수 있는 기반을 마련하였다.

• 한국해양공학회지
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• 제23권4호
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• pp.85-90
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• 2009

Although most of existing hydration heat control methods show a certain degree of hydration heat control, generally, there are many problems as mentioned above. Therefore, our laboratory previously developed a hydration heat control method using an exposed heat pipe, which solves most of these problems and simultaneously displays excellent hydration heat control. Unfortunately, even this method had some problems such as the processing, transport, and assembly of heat pipes, and the surface treatment of a cut plane after pouring, and hardening concrete. Therefore, in this study, a hydration heat control method using an embedded pipe has been developed with the expectation that this method solves those problems in hydration heat control using an exposed heat pipe. As a result of the experiment, the peak temperature of ECHP and ICHP specimen about $4.5{\sim}6.5^{\circ}C$ than the OPC specimen and the probability of thermal cracked generated in ECHP and ICHP specimen decreased up to $13{\sim}20%$. Finally, it was confirmed in this study that the hydration heat control method using an embedded heat pipe is significantly more superior and cost effective than the existing method of an exposed one.