• 한국가스학회지
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• 제25권1호
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• pp.7-13
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• 2021

재액화 드럼은 과냉각된 LNG를 증발가스에 직접 분사하기 위해 상부에 스프레이 노즐을 설치하고, 기액 분리가 용이하도록 데미스터를 설치한 제품으로, 소형 재액화 설비의 재액화 효율을 높이기 위해 개발한 제품이다. 드럼의 상온 내압기밀시험에서는 설계압력의 1.5배 이상의 압력에서도 누설(Leak)이 없었으나, 단열성능시험 중 온도변화에 따른 수축/팽창으로 인해 볼트풀림 현상이 발생하였다. 제품의 지속적인 사용을 위해 플랜지 결합부의 단열 시공은 탈부착이 가능하도록 개발하였으며, 기존 단열과의 열침입량 비교 결과 드럼 내 유입 유량 대비 매우 미미함을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.33-38
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• 2001

Bifurcation of unstable symmetric flow patterns to stable asymmetric ones in laminar sudden-expansion flow has been numerically investigated. Computations were carried out for an expansion ratio of 3 and over a range of the flow Reynolds numbers by using numerical methods of second-order time accuracy and a fractional-step method that guarantees divergence-free flowfields at all times. The critical Reynolds number above which bifurcation of pitchfork type to asymmetric flow pattern takes place is lower in a flow with a higher expansion ratio, in agreement with the previously reported results. The bifurcation diagrams show that the bifurcation takes place at a Reynolds number, $Re_c = 86.3$, higher than the value that has been reported. The lower critical Reynolds number may be due to deficiencies in their computations which employed SIMPLE-type relaxation methods rather than the initial-value approach of the present study. Characteristics of the flow development during the transition to asymmetric stable flow have been investigated by using spectral analysis of the velocity signals obtained by the simulations.

• Journal of Chest Surgery
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• 제22권2호
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• pp.321-324
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• 1989

The Swyer-James syndrome is rare abnormality that may be encountered on routine chest X * ray examination and frequently presents a diagnostic problem. Recently, we experienced a case of Swyer-James syndrome which was accompanied with ipsilateral uncontrolled pneumothorax. We performed exploratory thoracotomy because of failure of re-expansion of the lung. Right pneumonectomy was performed and postoperative course was uneventful.

• 설비공학논문집
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• 제13권2호
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• pp.96-105
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• 2001

R410a which is one of HFC refrigerants is being considered to be a promising replacement for R22 widely used in domestic air conditioners. The rolling piston type rotary compressors for R410a have lower energy efficiency than those for R22 because of the high pressure difference between a suction chamber and a discharge chamber in the compression mechanism. in addition, the re-expansion gas loss of the rotary compressor for R410a which occurs a ta clearance volume in a discharge port becomes larger than that for R22 due to high density of R410a refrigerant. Therefore, Pressure-Volume analyses for various design parameters of a discharge system were carried out to improve efficiency of a R410a rotary compressor. The results such as performance dta, over-compression loss, and re-expansion loss were acquired by P-V analyses and analyzed quantitatively. As a conclusion, the optimal specifications of several design parameters of a discharge system were obtained by analyzing P-V diagrams.

• 한국의상디자인학회지
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• 제25권3호
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• pp.165-184
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• 2023

The purpose of this study is to analyze the expanded characteristics that can be found in the fashion designs of JUUN. J. For the study, the concept and discourse related to theme expansion have been theoretically reviewed, and various types of expansive characteristics were derived by reviewing prior research related to the keyword expanded characteristics. Photo data required for the analysis were collected through the official website of JUUN. J and Vogue, a worldwide fashion magazine. The scope of the survey was limited to 983 photographs collected from 28 collections from 2009 S/S through 2022 F/W. The results are as follows. First, the expansion of the human body, which is achieved by adding an empty space between the body and the clothing or using various materials to express the volume of the body, is expressed through two different forms in the designs of JUUN. J. Second, the expansion of time expresses the combination of different timelines, the meeting of the past and present or awe toward the unpredictable future. Third, the expansion of style, which is expressed by reinterpreting existing costumes or styles, is a type of expansion' that appears individually in the fashion designs of JUUN J. Such expansion of style can be found in the military inspired designs. Fourth, the expansion of space, which diversifies our perception of space by re-recognizing the concept of space, was implemented into the works and designs of JUUN. J through the convergence of different cultural aspects. Fifth, the expansion of gender, which is expressed through the continuous exploration of the borders of gender and the delivery of social messages, has appeared in the works of JUUN J. in the form of genderless design.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.60-60
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• 2021

Investigating Backward-Facing Step(BFS) flow is important in that it is a representative case for separation flows in various engineering flow systems. There have been a wide range of experimental, theoretical, and numerical studies to investigate the flow characteristics over BFS, such as flow separation, reattachment length and recirculation zone. However, most of such previous studies were concentrated only on the perpendicular step angle. In this study, several numerical investigations on the flow pattern over BFS with various step angles (10° ~ 90°) and expansion ratios (1.48, 2 and 3.27) under different Reynolds numbers (5000 ~ 64000) were carried out, mainly focused on the reattachment length. The numerical simulations were performed using an open source 3D CFD software, OpenFOAM, in which the velocity profiles and turbulence intensities are calculated by RANS (Reynolds Averaged Navier-Stokes equation) and 3D LES (Large Eddy Simulation) turbulence models. Overall, it shows a good agreement between simulations and the experimental data by Ruck and Makiola (1993). In comparison with the results obtained from RANS and 3D LES, it was shown that 3D LES model can capture much better and more details on the velocity profiles, turbulence intensities, and reattachment length behind the step for relatively low Reynolds number(Re < 11000) cases. However, the simulation results by both of RANS and 3D LES showed very good agreement with the experimental data for the high Reynolds number cases(Re > 11000). For Re > 11000, the reattachment length is no longer dependent on the Reynolds number, and it tends to be nearly constant for the step angles larger than 30°.) Based on the calibrated and validated numerical simulations, several additional numerical simulations were also conducted with higher Reynolds number and another expansion ratio which were not considered in the experiments by Ruck and Makiola (1993).

• 한국산업정보학회논문지
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• 제25권6호
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• pp.125-141
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• 2020

본 연구는 세무서비스 고객을 대상으로 서비스 확대에 미치는 영향 및 차별화된 서비스영역 확대시 내부종사자의 심리적 주인의식 (Psychological ownership)의 정도에 따른 고객의 재이용의도의 변화와 대표자의 성향에 따른 수익강조, 비용강조, 이중강조(Revenue and cost dual emphasis)의 영향에 대한 분석을 하였다. 연구결과, 이용자들의 고객만족도를 충족시키고 내부종사자의 심리적 주인의식에 따른 계속적인 고객의 재이용의도의 변화를 볼 수 있었다. 또한, 세무대리인이 미래지향적 서비스 제공의 방향 전환을 추구할 수 있도록 하는데 의의가 있으며, 세무대리인의 전문성, 품질, 서비스확대 측면에서 새로운 연구 방향을 제시하였다.

• 전자공학회논문지CI
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• 제46권1호
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• pp.64-77
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• 2009

ID기반 재암호화 기법(ID-based foxy re-encryption scheme)은 사용자 간의 복호 능력 위임을 가능하게 하며 분산 데이터 저장, DRM, 이메일 전달 시스템 등의 다양한 분산 암호시스템을 위해 활발히 연구되고 있다. 최근 재암호화키 생성의 비상호성(Non-interactivity)을 제공하는 기법이 Green과 Ateniese에 의해 제안되었다. 이 기법은 선택 암호문 공격에 대한 안전성을 제공하기 위해 설계되었다. 본 논문에서는 Green-Ateniese ID기반 재암호화 기법이 근본적으로 사용자 키 노출 공격에 취약함을 보이고 선택 암호문 공격에 대한 안전성이 보장되지 않음을 증명한다. 그리고 이러한 보안 취약점을 해결하는 새로운 두 가지 ID기반 재암호화 기법들을 제안한다. 제안 기법들이 랜덤 오라클 모델(Random Oracle Model)에서 단순 평문 공격과 선택 암호문 공격에 대해 각각 안전함을 증명한다. 선택 암호문 공격에 안전한 제안 기법을 구성하기 위해, 본 논문에서는 최초로 짧은 서명에 기반한 자가 인증 기법을 고안하여 적용한다. 제안 기법의 중요한 특징은 재암호화 후 암호문의 구조가 유지되는 것이다. 따라서 이전 기법들과는 대조적으로 암호문 확장이 발생되지 않는다. 또한 재암호화의 횟수에 제한이 없어서 연속적인 암호문 변환이 가능하여 다중의 사용자를 위한 복호 능력 위임을 구현할 수 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.936-939
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• 2002

FPCA is the necessary device to design of hardware at present, it is researched on many ways of applying to design caused by expansion of capacity in recent years. One of these applying ways is SoC (System on a Chip) that is proposed for realizing the basic function of a system. For realizing SoC efficiently, IP (Intellectual property) is very important and developed for re-use of hardware. A MPU for built-in exists as an IP. But almost of MPUs at present as an IPs are lengthy and large-scale for using embedded-application. Furthermore, the function of executing specific treatment critically is required to embedded MPU. We propose a flexible and small scale MPU and its design method.

• 건축역사연구
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• 제7권2호
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• pp.127-140
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• 1998

It seems obvious to the contemporary eye that modern technology has finally brought chaotic abundance to the present world, and provided a superficial civilization over the last century. Nevertheless, such an argument about the external phenomena of present culture does not help constitute the right track of modern technology and architecture. Rather, this discussion comes to re-signify the importance of critical metaphysics as a part of man's cultural activities, especially the ontological meaning of them. In this point, the research is intended both to re-certify the essential nature and mythic value of technology through reviewing the ancient and modern philosophical contemplations, and to examine its architectural condition against the rapid expansion of commercial material-culture.