• 한국정보통신학회논문지
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• 제24권8호
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• pp.1058-1063
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• 2020

본 논문에서는 IT 접지 시스템의 감전 및 화재사고 방지를 위한 새로운 절연 저항 계산 기법을 소개한다. 최근 신재생 에너지와 에너지 저장 장치의 확대 보급으로 태양광 발전 시장이 급속하게 성장하고 있으나 절연이 파괴되어 화재사고가 빈번히 발생함에 따라 IT 접지 방식에도 절연 저항 상태를 감시하는 장치가 필수적으로 요구되고 있다. 제안하는 절연 저항 계산 기법은 기존의 고정된 시정수곱 계수기반의 알고리즘에 비해 절연 임피던스의 조건에 따라 동적시정수곱계수를 적용함으로써 넓은 절연 저항 범위에서 빠른 응답 시간과 높은 정확도를 갖는다. 제안하는 동적 시정수 기반 절연 저항 계산 기법은 기존의 방법에 비해 최대 응답 시간은 39.29초, 오차율은 20.11%를 개선시키는 효과를 보였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.688-691
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• 1997

Good quality superconducting $YBa_2Cu_30_{7-{\delta}}$(YBCO) thin films were grown on Hastelloy (Ni-Cr-Mo alloys) with yttria-stabilized zirconia(YSZ) buffer layers by in situ pulsed laser deposition in a multi-target processing chamber. Generally, Hastelloy exhibits excellent resistance to corrosion, fatigue, thermal shock, impact, and erosion. However, it is difficult to make films on flexible metallic substrates due to interdiffusion problems between metallic substrates and superconducting overlayers. To overcome this difficulty, it is necessary to use YSZ buffer layer since it will not only limit the interdiffusion process but also minimize the surface microcrack formation due to smaller mismatch between the film and the substrate. In order to enhance the crystallinity of YBCO films on metallic substrates, YSZ buffer layers were grown at various temperatures different from the deposition temperature of YBCO films. On YSZ buffer layer grown at higher temperature than that for depositing YBCO film, the YBCO thin film was found to be textured with c-axis orientation by x-ray diffraction and had a zero-resistance critical temperature of about 85K.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 학술대회 논문집
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• pp.257-259
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• 2005

In recent years the developments of the society in information technology so the building is required protective earthing to prevent electric shock and the building is also required functional earthing to guarantee safe operation of dispatch instrument of information. This paper is reviewed about an estimation of earthing resistance that is considered the shape and size of the plate electrode in order to do practical use as earthing electrode of foundation the plate electrode in the foundation of building.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.215-216
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• 2019

The following conclusions were reached through the research on the development of the required performance extraction tools for the application and utilization of various construction methods of lightweght dry wall. 1) Performance required for walls of apartment buildings can be divided into safety, habitation, durability and productivity. Among these, horizontal load resistance, shock resistance, anti-seismic performance, insulation, and acoustic characteristics are the main performance that correspond to dry walls. In addition, safety related to toxic gases and contaminants are required according to recent eco-friendly requirements. 2) To select a wall according to the required performance of an inner wall applied to an apartment, a map tool in the form of 2D matrices was constructed to enable the required performance to be applied, indicating that the wall location and wall material and its differentiating according to the old method.

• 수산해양기술연구
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• 제31권4호
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• pp.413-422
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• 1995

각종 환경 조건에서 진동 캐비테이션 침식-부식 시험 장치에 의해 연강(SS41)의 캐비테이션 침식-부식 손상 거동에 관한 연구를 한 결과 다음과 같은 결론을 얻었다. 1) 해수 중에서 캐비테이션 침식-부식 손상 거동은 중앙부와 테두리 부에서 거의 비슷한 정도로 발생하여 성장되지만, 증류수 중에서는 테두리부에서 손상이 먼저 발생한 다음 중앙부에도 손상이 점차 일어난다. 2) 비저항이 낮은 수도수 중의 캐비테이션 침식-부식 손상은 초기에는 비저항이 높은 증류수중에서의 것보다 증가하지만 시간이 경과하면서 CaCO 하(3)의 피막 형성에 의해 둔화된다. 3) 케비테이션 침식-부식 손상 특성은 잠복기, 증가기, 감소기 및 안정기의 4단계로 구분된다.

• Journal of Welding and Joining
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• 제34권1호
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• pp.26-34
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• 2016

Automotive today has been transforming to an electronic product by adopting a lot of convenience and safety features, suggesting that joining materials and their mechanical reliabilities are getting more important. In this study, a Sn-Cu-Cr-Ca solder composition having a high melting temperature ($>230^{\circ}C$) was fabricated and its joint properties and reliability was investigated with an aim to evaluate the suitability as a joining material for electronics of engine room. Furthermore, mechanical properties change under complex environment were compared with several existing solder compositions. As a result of contact angle measurement, favorable spreadability of 84% was shown and the average shear strength manufactured with corresponding composition solder paste was $1.9kg/mm^2$. Also, thermo-mechanical reliability by thermal shock and vibration test was compared with that of the representative high temperature solder materials such as Sn-3.5Ag, Sn-0.7Cu, and Sn-5.0Sb. In order to fabricate the test module, solder balls were made in joints with ENIG-finished BGA and then the BGA chip was reflowed on the OPS-finished PCB pattern. During the environmental tests, resistance change was continuously monitored and the joint strength was examined after tests. Sn-3.5Ag alloy exhibited the biggest degradation rate in resistance and shear stress and Sn-0.7Cu resulted in a relatively stable reliability against thermo-mechanical stress coming from thermal shock and vibration.

• 한국세라믹학회지
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• 제31권5호
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• pp.572-580
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• 1994

With low thermal expansion coefficients, eucryptite (Li2O.Al2O3.2SiO2) and spodumene (Li2O.Al2O3.4SiO2) in LAS ceramic system show good thermal shock resistance. In this study, sillimanite or kaolin group silicate minerals and Li2CO3 were used as starting materials, and if necessary SiO2 or Al2O3 were added for making stoichiometrically formed specimens. By this process, eucryptite powders were synthesized and characterized. The powder mixtures of lithiumcabonate and silicate minerals calcined at 80$0^{\circ}C$ for 2 hrs were made into powder compacts. $\beta$-Eucryptite single phase was formed via intermediate phases of Li2SiO3 and LiAlO2 et al, by heating at 110$0^{\circ}C$ or 120$0^{\circ}C$ for 10 hrs from those powder compacts. When using the sillimanite group minerals, Virginia kyanite or andalusite was reacted to form eucryptite at 120$0^{\circ}C$and CMK International kyanite were completed at 110$0^{\circ}C$. When kaolin group minerals were used, it was found that the synthesizing temperature (100$0^{\circ}C$) of $\beta$-eucryptite from the mixture of New Zealand white kaolin was lower than that from Hadong pink kaolin (110$0^{\circ}C$). The Microstructure of systhesized powder showed the irregular lump shape such as densed crystallines.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.975-983
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• 2022

A four-layered W/Cu functionally graded material (FGM) (W90% + Cu10%/W80% + Cu20%/W70% + Cu30%/W60% + Cu40%, wt.% fraction) and a four-layered diamond/W-Cu FGM (W90% + Cu10%/W80% + Cu20%/W70% + Cu30%/W55% + Cu40% + diamond5%, wt.% fraction) were fabricated by microwave sintering. The thermal conductivity and thermal shock resistance of diamond/W-Cu FGM and W-Cu FGM were investigated. The morphologies of the diamond particles and different FGMs were analyzed using AFM, SEM, EDS, and TEM. The results show that a 200 nm rough tungsten coating was formed on the surface of the diamond. The density of the tungsten-coated diamond/W-Cu FGM, obtained by microwave sintering at 1200 ℃ for 30 min, was 94.66%. The thermal conductivity of the fourlayered diamond/W-Cu FGM was 220 W·m^-1·K^-1, which is higher than that of the four-layered W/Cu FGM (209 W m^-1 K^-1). This indicates that adding an appropriate amount of tungsten-coated diamond to the high Cu layer W/Cu FGM improves the thermal conductivity of the composite. The diamond/W-Cu FGM sintered at 1200 ℃ for 10 min exhibited better thermal shock resistance than diamond/W-Cu FGM sintered at 1100 ℃ for 10 min.

• Journal of Ginseng Research
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• 제47권4호
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• pp.524-533
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• 2023

Background: Obesity is a risk factor for aging and many diseases, and the disorder of lipid metabolism makes it prominent. This study aims to investigate the effect of ginsenoside Rg1 on aging, lipid metabolism and stress resistance Methods: Rg1 was administered to Caenorhabditis elegans (C. elegans) cultured in NGM or GNGM. The lifespan, locomotory activity, lipid accumulation, cold and heat stress resistance and related mRNA expression of the worms were examined. Gene knockout mutants were used to clarify the effect on lipid metabolism of Rg1. GFP-binding mutants were used to observe the changes in protein expression Results: We reported that Rg1 reduced lipid accumulation and improved stress resistance in C. elegans. Rg1 significantly reduced the expression of fatty acid synthesis-related genes and lipid metabolism-related genes in C. elegans. However, Rg1 did not affect the fat storage in fat-5/fat-6 double mutant or nhr-49 mutant. Combined with network pharmacology, we clarified the possible pathways and targets of Rg1 in lipid metabolism. In addition, Rg1-treated C. elegans showed a higher expression of anti-oxidative genes and heat shock proteins, which might contribute to stress resistance Conclusion: Rg1 reduced fat accumulation by regulating lipid metabolism via nhr-49 and enhanced stress resistance by its antioxidant effect in C. elegans.

• Journal of Chest Surgery
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• 제39권12호
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• pp.913-919
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• 2006

배경: 혈관 확장성 쇼크는 체외 순환을 이용한 심장 수술 후 전신성 염증 반응으로 발생할 수 있는 치명적인 합병증이다. 이러한 혈관 확장성 쇼크에서는 바소프레신의 분비가 감소되어 있으므로 바소프레신을 투여함으로써 효과적인 혈역학적 호전을 가져올 수 있다. 따라서, 심장 수술 후 혈관 확장성 쇼크가 발생한 환자에서 바소프레신 치료 요법에 관한 본원의 경험을 보고하고자 한다. 대상 및 방법: 본 연구는 2004년 1월부터 2006년 7월까지 체외 순환을 통한 심장 수술을 받은 199명 중에서 혈관 확장성 쇼크가 발생한 22명의 환자를 대상으로 하였다. 혈관 확장성 쇼크는 평균 동맥압 70 mmHg 이하, 심장 박출 지수 2.5 $L/min/m^2$ 이상, 전신 혈관 저항 800 $dyn/s/cm^5$ 이하, 카테콜아민 혈압상승제가 필요한 경우로 정의하였다. 이러한 기준으로 진단된 혈관 확장성 쇼크 환자에게 바소프레신을 투여하고 혈역학적 변화를 후향적으로 분석하였다. 결과: 심장 질환으로 체외 순환을 이용한 심장 수술을 받은 성인 환자 199명 중에서 22명이 혈관 확장성 쇼크로 진단되었다. 이들은 과량의 카테콜아민 혈압 상승제를 투여하였으나 평균 동맥압은 70 mmHg 이하로 유지되어 바소프레신 치료 요법을 시행하였다. 바소프레신 투여 1시간 후 평균 동맥압은 $53.3{\pm}7.4$ mmHg에서 $82.0{\pm}12.0$ mmHg로 의미 있게 상승하였고, 혈압 상승제 요구량은 $25{\pm}7$에서 $18{\pm}6$로 의미 있게 감소되었으며, 각각 12시간 동안 유지되었다. 결론 바소프레신은 혈관 확장성 쇼크 환자에게 안전하고 효과적으로 사용할 수 있는 혈압 상승제이다. 심장 수술 후 발생한 혈관 확장성 쇼크 환자에서 적극적으로 바소프레신 치료요법을 시행한다면 과량의 카테콜아민 혈압 상승제 투여로 인한 합병증을 줄이고 효과적인 혈류역학적인 호전을 가져올 수 있을 것이다.