• 설비공학논문집
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• 제13권12호
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• pp.1223-1229
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• 2001

Though conventional calorimetry methods such as differential scanning calorimetry (DSC) and differential thermal analysis (DTA) are used generally in measuring heat of fusion, T-history method has the advantages of a simple experimental apparatus and no requirements of sampling process, which is particularly useful for measuring thermal properties of inhomogeneous phase change materials (PCMs) in sealed tubes. However, random criteria (a degree of supercooling) used in selecting the range of latent heat release and neglecting sensible heat during the phase change process can cause significant errors in determining the heat of fusion. In the present study, it was shown that a 40% discrepancy exists between the original T-history and the present methods when analyzing the same experimental data. As a result, a reasonable modification to the original T-history method is proposed.

• International Journal of Air-Conditioning and Refrigeration
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• 제11권1호
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• pp.32-39
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• 2003

Though conventional calorimetry methods such as differential scanning calorimetry and differential thermal analysis are used generally in measuring heat of fusion, T-history method has advantages of a simple experimental apparatus and no requirements of sampling process, which is particularly useful for measuring thermophyical properties of in-homogeneous phase change materials in sealed tubes. However, the degree of supercooling used in selecting a range of latent heat release and neglecting sensible heat during the phase change process can cause significant errors in determining the heat of fusion. In the present study, it was shown that a 40% discrepancy exists between the original T-history and the present methods when analyzing the same experimental data. As a result, a reasonable modification to the original T-history method is proposed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.226-231
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• 2001

The purpose of this paper is to propose the experimental method of thermal properties of Phase Change Materials (PCMs) by using T-history method. As far, in order to measure the heat of fusion and specific heat of PCMs, conventional thermal analysis methods such as DSC and DTA have been used. Because these methods test very small samples, thermal properties of samples are usually different from those of materials consisting of several components. For these reasons, T-history method, the simple measurement method of the heat of fusion and specific heat of PCMs have been performed. In this paper, we investigated the thermal properties of low temperature PCMs(below $0^{\circ}C$) under the charging process by using T-history method. The results are compared to those of DSC method. The T-history method will be useful for selection of the best PCM from lots of candidates and development of new PCMs.

• 설비공학논문집
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• 제15권8호
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• pp.652-660
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• 2003

T-history method, measuring heat-of-fusion of phase change material (PCM) in sealed tubes, has the advantages of a simple experimental device and no requirements in sampling process. However, a degree of supercooling used in selecting the range of latent heat release and neglecting sensible heat during the phase change process can cause significant errors in determining the heat of fusion in the original method, which has been improved in order to predict better results by us. In the present study, the modified method was applied to a variety of PCM such as paraffin and lauric acid having very small or no supercooling with a satisfactory precision. Also the selection of inflection point and temperature measurement position was fumed out not to affect the accuracy of heat-of-fusion significantly. As a result, the method can provide an appropriate means to assess a new developed PCM by cycle test even if a very accurate value cannot be obtained.

• 소성∙가공
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• 제22권3호
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• pp.123-132
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• 2013

Hot stamping, which is the hot pressing of special steel sheet using a cold die, can combine ease of shaping with high strength mechanical properties due to the hardening effect of rapid quenching. In this paper, a thermo-mechanical analysis of hot stamping using the finite element method in conjunction with phase transformations was performed in order to investigate the plastic deformation behavior, temperature history, and mechanical properties of the stamped car part. We also conducted a fully coupled thermo-mechanical analysis during the stamping and rapid quenching process to obtain the mechanical properties with the consideration of the effects of plastic deformation and phase transformation on the temperature histories at each point in the part. The finite element analysis could provide key information concerning the temperature histories and the sheet mechanical properties when the phase transformation is properly considered. Such an analysis can also be used to determine the effect of cyclic cooling on the tooling.

• 천문학회보
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• 제44권1호
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• pp.40.1-40.1
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• 2019

We utilize times since infall of cluster galaxies obtained from Yonsei Zoom-in Cluster Simulation (YZiCS), the cosmological hydrodynamic N-body simulations, and star formation rates from the SDSS data release 10 to study how quickly late-type galaxies are quenched in the cluster environments. In particular, we confirm that the distributions of both simulated and observed galaxies in phase-space diagrams are comparable and that each location of phase-space can provide the information of times since infall and star formation rates of cluster galaxies. Then, by limiting the location of phase-space of simulated and observed galaxies, we associate their star formation rates at z ~ 0.08 with times since infall using an abundance matching technique that employs the 10 quantiles of each probability distribution. Using a flexible quenching model covering different quenching scenarios, we find the star formation history of satellite galaxies that best reproduces the obtained relationship between time since infall and star formation rate at z ~ 0.08. Based on the derived star formation history, we constrain the quenching timescale (2 - 7 Gyr) with a clear stellar mass trend and confirm that the refined model is consistent with the "delayed-then-rapid" quenching scenario: the constant delayed phase as ~ 2.3 Gyr and the quenching efficiencies (i.e., e-folding timescale) outside and inside clusters as ~ 2 - 4 Gyr (${\propto}M_*^{-1}$) and 0.5 - 1.5 Gyr (${\propto}M_*^{-2}$), Finally, we suggest: (i) ram-pressure is the main driver of quenching of satellite galaxies for the local Universe, (ii) the quenching trend on stellar mass at z > 0.5 indicates other quenching mechanisms as the main driver.

• 한국의사학회지
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• 제22권2호
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• pp.33-41
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• 2009

The objective of this article is to analysis of Acupuncture & Moxibustion Fix-a-day Method (AMFDM) shown in the acupuncture documents of the Chosun-Korea dynasty. Through such inquisition, The development process of AMFDM could be found. cross-comparison analysis of the contents of three medical books, Chim-Gu-Tek-Il-Pien-Zip(CGTIPZ), Dong-Eui-Bo-Gam(DEBG) and Chim-Gu-Gyung-Hum-Bang (CGGHB) of the Chosun-Korea dynasty. The development process of AMFDM of the three books is different from each other, depending on the purpose of writing books. But The three books contain common parts. It could be divided into three types, Simple-AMFDM, Extensive-AMFDM and Spirit-Existence-AMFDM. The development process of AMFDM of the Chosun-Korea dynasty has three steps. First, Integration and specialization phase in CGTIPZ. CGTIPZ sum many kind of AMFDMs up, and compare them to be specialized area. Second, Setting theory phase in DEBG. DEBG theorize AMFDM made of Spirit-Existence-AMFDM. Third, Practical use phase in CGGHB. CGGHB invented practical reinforcement to replace complicated ones.

• 한국수학사학회지
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• 제19권2호
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• pp.59-76
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• 2006

본 논문은 탈근대화의 영향으로 등장한 카오스 이론의 시각으로, 수학과 미술의 관련성을 연구하였다 중세 말에서 르네상스로 접어드는 13-14세기, 르네상스의 개화기인 15, 16세기 그리고 16세기말에서 바로크 시대로 접어드는 세 시기에 시대정신이 역동적 체계에서 어떻게 구축되는지를 조망하였다. 시간의 흐름과 더불어 역동적으로 변모해가는 문화와 역사는복잡계의 전형이기 때문이다.

• 한국수학사학회지
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• 제22권2호
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• pp.117-130
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• 2009

본 연구는 중학교 이차방정식 단원에서 조선시대(朝鮮時代) 수학사(數學史)를 효과적으로 활용하기 위해 먼저, 수학교육에서 수학사의 활용과 중학교 수학 교과서에서 다루고 있는 수 학사의 유형 및 그 내용을 살펴보고, 조선시대의 수학자인 경선징(慶善徵), 홍정하 (洪正夏), 이상혁(李尙赫) 등이 제시하는 이차방정식의 구성과 해법에 대해 조사하여 중학교 수학에서 활용할 수 있는 방법에 대해 알아보았다. 이와 같은 조선시대 수학사는 이차방정식에 대한 이해를 높이고 풀이에 대한 흥미와 동기를 유지시키기 위한 자료, 활용 단계에서 개념적 사고와 반성적 사고를 고취시키기 위한 자료로 활용할 수 있다.

• 건축역사연구
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• 제7권4호
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• pp.131-150
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• 1998

Main theme of this study is the acceptance phase of western architectural culture in modern east-north asia through a series of actual survey and typological analysis of existing church buildings in modern Korea. China. Japan. For this study, 126 modern church buildings of Korea, China, Japan are selected. Also, main subject of this study has deal with the side of culture - thought which background of christianity acceptance and acceptance mind of acceptance main-body, culture adaptation and transformation based on characteristic culturalization of Korea, China, Japan. Especially, I would consistently tried to see the acceptance phase of western architectural culture according to differential acceptance mind of acceptance main-body based on characteristic culturalization of three countries. Conclusively, in the point of view of western architectural culture acceptance phase, it could be said that Korean church architecture had characterized as a blending phase of the two eclectic architectural culture. And in the case of china, as a coexistance phase of the two architectural culture with more western style-oriented. On the other hand, Japanese church architecture had characterized as a syncretism phase of the both traditional and western architectural culture, though it is eclectic style-oriented. Therefore, it is thought that different acceptance mind of western culture had main factors caused of differential acceptance phase, when the two architectural culture, the traditional and the western, encounters.