• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.11.2-11.2
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• 2009

Au-Ag 합금 박막에서 화학적으로 덜 안정한 Ag를 선택적으로 에칭하는 dealloying 기법을 통하여 crack-free 나노기공 gold 박막을 Si 기판에 제조하였다. Au-Ag 합금 박막은 두 가지 방법을 이용하였다: 1) thermal 또는 electron beam 증착법을 이용하여 Au 와 Ag 다층 박막을 Si 기판에 증착시킨 후 열처리를 통한 합금 박막제조; 2) co-thermal 증착법을 이용하여 Au-Ag 합금박막을 Si 기판에 직접 증착. Crack-free 나노기공 gold 박막 제조에 적합한 합금조성을 얻기 위하여 증착 속도, 열처리조건, dealloying 조건등을 조절하였다. Perchloric acid, HClO4 전해질을 이용한 전기화학적 dealloying을 통하여 crack-free 나노기공 gold 박막을 제조하였고, 기공크기를 조절할 수 있었다. 이에 더하여, electrophoretic 방법을 이용하여 나노기공 gold와 semiconductive 양자점 (CdTe 또는 CdSe)의 나노복합박막을 형성시킨 후 특성을 분석하였다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.938-943
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• 2006

The primary purpose of a computer room of data center and associated infrastructure is to support the operation of critical IT equipment. Traditionally, most owners of large critical data centers have been more than willing to accept a reasonable amount of computer room worker discomfort if necessary to support critical IT systems. All electrical equipment produces heat, which must be removed to prevent the equipment temperature from rising to an unacceptable level. Most information technology equipment and other equipment found in a data center or network room is air-cooled. Sizing a cooling system requires an understanding of the amount of heat produced by the equipment contained in the enclosed space, along with the heat produced by the other heat sources typically encountered.

• 한국해양공학회지
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• 제1권1호
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• pp.111-119
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• 1987

The corrosion fatigue crack propagation characteristics of SS41 steel in 3.5% NaCl solution have been evaluated for loading frequencies of 1Hz and 0.2Hz. A sine wave loading profile was used for fatigue testing. Each test was carried out at a constant stress ratio, R(0.1). The main results are summarized as follows; 1. Fatigue crack propagation rate was higher in 3.5% NaCl solution than in air, higher in the base metal than in the weld metal, and higher at f =0.2Hz than at f =1Hz. 2. The crack closure level of the base metal was not influenced by cyclic frequencies, but that of the weld metal was much influenced. 3. When the crack closure effect was eliminated in the evaluation of crack propagation characteristics by using $\Delta K_{eff}$, the envirommental influence was distinctly observed. At the base metal, crack propagation rate was enhanced by the hydrogen embrittlement, and the weld metal was reduced by the crac closure. 4. There was clearly observed hydrogen embrittlement and severely corroded aspect at fracture surface of lower frequency than that of higher frequency, and at that of base metal than that of the weld metal.

• 설비공학논문집
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• 제30권2호
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• pp.83-91
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• 2018

A datacenter is a high energy consuming facility whose cooling energy consumption rate is 10~20 times larger than general office buildings. The higher the temperature of supply air from a CRAC (computer room air-conditioner) is supplied, the more energy efficient cooling is possible because of improving the COP of a chiller and advanced range of outdoor air temperature available for the economizer cycles. However, because the temperature of cold air flowing into server computers varies depending on air mixing configurations in a computer room, the proper supply air temperature must be considered based on the investigation of air mixing and heat dissipation. By these, this study aims to understand the effects of variation of the supply air temperature on the air flow distributions, temperature distributions and rack cooling efficiencies. Computational fluid dynamics (CFD) aided in conducting the investigation. As a result, the variation of the supply air temperature does not affect the air flow distributions. However, it mainly affects the temperature distribution. From the results of CFD simulations, Rack cooling indices (RCIHI and RCILO) were evaluated and showed the ideal state set at $19^{\circ}C$ of the supply air temperature.

• 설비공학논문집
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• 제28권5호
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• pp.178-185
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• 2016

This study describes the analysis of a 20 MW chilled water plant used for the IT cooling of a recently constructed data center in Korea. The CFD model was developed with the aim of evaluating the impact of problems such as chiller failure on the water and air temperatures in the cooling system. The numerical model includes the chilled water hydraulic network and individual water-to-air CRAC units. The coupling between the IT server room air temperature levels and the cooling plant has enabled a full assessment of the cooling system design in response to system fault conditions to be performed. The paper examines an emergency situation involving the failure of the cooling plant, and shows how the inherent thermal inertia of the system along with additional inertia achieved through buffer systems allowed a suitable design to be achieved.

• PNF and Movement
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• 제6권1호
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• pp.27-32
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• 2008

Purpose : The purpose of this study is to review of effect of the PNF application for improvement of the basic physical fitness in the elderly. Methods : By using internet, we research the PubMed, Science Direct, KISS, DBpia and the article on the effect of PNF. We selected the article between 1970 and 2007. Key words were PNF, Exercise, Elderly. Results : PNF refers to any of several post-isometric relaxation stretching techniques in which a muscle group is passively stretched, then contracts isometrically against resistance while in the stretched position, and then is passively stretched again through the resulting increased range of motion. Most PNF techniques employ isometric agonist contraction/relaxation where the stretched muscles are contracted isometrically and then relaxed. The most common PNF techniques are CR, HR, CRAC, HR-AC, AC. PNF exercise effected on the muscular strength and flexibility and balance and ROM in the elderly. Conclusion : PNF is a safety and effective exercise to improve the muscular strength and flexibility and balance and ROM in the elderly. Therefore, we suggest that PNF need to generalize for the elderly.

• 한국전문물리치료학회지
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• 제1권1호
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• pp.55-60
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• 1994

Thirty healthy adults aged 20 to 29 with no history of musculoskeletal or neurogenic disorder volunteered for this study. The contract-relax with agonist contration(CRAC) was applied to the right hamstring muscles with the subject in the supine position. Each hamstring group was stretched on three sucessive days with several repetitions of the technique lasting 1min, 3min, and 5min. respectively. Hamstring extensibility at the knee(ROM) was measured before and after stretching using on electronic digital inclinometer(EDI). The results, namely the increase in ROM, were analysed using one-way repeated ANOVA at p<0.05. The differences were not significant. Possible factors influencing the results are excessive sensitibility of the measuring instrument, the psychological and physical status of the subjects, and the level of muscle fatigue. The mean increases in ROM were 3.0 at 1min., 2.6 at 3min, and 2.1 at 5min. Inclusion of a control group would have further defined the effects of the stretching technique.

• 실천공학교육논문지
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• 제15권2호
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• pp.429-438
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• 2023

최근 4차 산업혁명 시대에 부응하여 스마트 팩토리 수요가 증가하고 있다. 스마트 팩토리는 기본적으로 방대한 데이터를 기반으로 하는 제조업으로 많은 데이터 처리를 위한 IT 서비스를 필요로 하게 되고 이는 데이터센터의 건립을 가속화하고 있다. 데이터센터의 전산장비는 발열부하와 사용시간 측면에서 일반적인 시설의 냉방 기술과는 다른 차원으로 접근이 필요하다. 본 연구는 최근 데이터센터 냉방 시스템 설계에서 검토해야 할 요인과 기술 변화 트렌드를 조사하고 사례기업의 시설 구성을 위한 각종 기술적 방식을 비교 검토하여 설계안을 결정하는 프로세스를 도출하고 결론에 해당하는 개념 설계안을 제시하고자 한다.

• The Korean Journal of Physiology and Pharmacology
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• 제2권2호
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• pp.133-145
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• 1998

$Ca^{2+}-signals$ in endothelial cells are determined by release from intracellular stores and entry through the plasma membrane. In this review, the nature of $Ca^{2+}$ entry and mechanisms of its control are reviewed. The following ion channels play a pivotal role in regulation of the driving force for $Ca^{2+}$ entry: an inwardly rectifying $K^+$ channel, identified as Kir2.1, a big-conductance, $Ca^{2+}-activated$ $K^+$ channel (hslo) and at least two $Cl^-$ channels (a volume regulated $Cl^-$ channel, VRAC, and a $Ca^{2+}$ activated $Cl^-$ channel, CaCC). At least two different types of $Ca^{2+}$-entry channels exist: 1. A typical CRAC-like, highly selective $Ca^{2+}$ channel is described. Current density for this $Ca^{2+}$ entry is approximately 0.1pA/pF at 0 mV and thus 10 times smaller than in Jurkat or mast cells. 2. Another entry pathway for $Ca^{2+}$ entry is a more non-selective channel, which might be regulated by intracellular $Ca^{2+}$. Although detected in endothelial cells, the functional role of trp1,3,4 as possible channel proteins is unclear. Expression of trp3 in macrovascular endothelial cells from bovine pulmonary artery induced non-selective cation channels which are probably not store operated or failed to induce any current. Several features as well as a characterisation of $Ca^{2+}$-oscillations in endothelial cells is also presented.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 춘계학술대회
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• pp.159-161
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• 2013

기업 및 기관의 통신실 및 전산실에서 운영하는 UPS, 항온항습기, 소화설비와 같은 기반설비에 대하여 발생할 수 있는 각종 장애를 사전에 감지하고, 장애 발생 시 신속히 대응할 수 있는 감시체제에 대하여 체계적으로 연구하고자 한다. 주요 통신설비 및 전산설비를 운영, 관리하는 환경에서는 공조기의 작동상태, 분전반 및 UPS의 상태 및 고장 유무, 화재발생시 신속한 통보체계가 필요하다. 기존 전산실의 주변 기반설비 장애 감시에 대한 현황 및 문제점을 파악함으로써 향후 체계적인 감시시스템 구축을 위한 개념 정립과 실무자들이 설계 시에 참조하여야 할 고려 사항들을 관리지침으로 제시하여 향후 데이터센터 감시시스템 구축과 관련한 다양한 연구의 필요성을 제시하고자 한다.