• 대한화학회지
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• 제14권4호
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• pp.321-326
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• 1970

The relation between the heating temperature and the V.C.P(Vacuum Condensing Point) at different degree of vacuum through the sublimatographic separation was studied where by ; (1) Anthracene and Anthraquinone, ${\alpha}$-Naphtol and ${\beta}$-Naphthol, o-Aminobenzoicacid and p-Aminobeenzoicacid were easily separated from each of its mixtures as shown in Figure9, 10 and 11, while tailings appeared appreciably. The results were in good agreement with those expected from the $t_k$-V.C.P curves in Figures 3,4,5,6,7 and 8. (2) The relation between the degree of vacuum and the V.C.P. of ${\alpha}$-Naphthol and Anthracene at different heating temperatures appeared as follows and are shown in Figures 12 and 13.

• 한국초전도ㆍ저온공학회논문지
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• 제24권3호
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• pp.74-78
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• 2022

Two β=0.10 cryomodules are required for the China Accelerator Driven Subcritical System (C-ADS) injector II accelerator. Flow design is of great importance in the performance of cryomodules, including thermal design, flow distribution, pressure drop and so on. This paper will study convection heat transfer of helium and relation among the pipe diameter, mass flow rate and Reynolds number. Furthermore, the influence of flow geometries on pressure drop and flow distribution will also be done. It was found that the theoretical flow distribution were in good agreement with the experimental data.

• Journal of Advanced Marine Engineering and Technology
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• 제18권5호
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• pp.12-23
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• 1994

The two-phase flow is observed in power plants, chemical process plants, and refrigeration systems etc., and it is very important to solve the heat transfer mechanism of a boiler, an automic reactor, a condenser and various types of evaporators. Recently, the problem of two phase heat transfer is braught up in many regions with development of energy saving technique. In flow boiling system it is necessary to store data in each condition because the heat transfer characteristics of flow boiling region vary by the change of flow pattern and the magnetude of heat flux to tube length, and be subtly affected by the flow and heating condition. So basic study for knowing flow pattern in heat transfer region and the relation between heat transfer characteristic and flow condition is desired to accumulate data in wide variety of liquid and flow system in the study of heat transfer of two phase flow. In this study R-113 was selected as working fluid whose properties were programmed by least square method, and experiment was conducted in the region of mass flow $1.628{\times}10^6$~$4.884{\times}10^6$/kg/$m^2$hr with inlet subcooling 10~3$0^{\circ}C$, sustaining test section inlet pressure to 1.5kg$_f$/$cm^2$abs.

• International Journal of Air-Conditioning and Refrigeration
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• 제13권1호
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• pp.51-60
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• 2005

This paper reviews the studies on the pressure drop and the heat transfer in microchannels. Although a lot of studies about the single-phase flow have been done until now, conflicting results are occasionally reported about flow transition from laminar flow to turbulent flow, friction factor, and Nusselt number. Some studies reported the early flow transition due to relatively greater wall effect like surface roughness, but the other studies showed that the flow transition occurred at the Reynolds number of about 2300 and the early flow transition might be due to less accurate measurement of the channel geometry. Also, there have been arguments whether the conventional relation based upon continuum theory can be applied to the fluid flow and the heat transfer in microchannels without modification or not. The studies about the two-phase flow in microchannels have been mostly about investigating the flow pattern and the pressure drop in rectangular channels using two-component, two-phase flow like air/water mixture. Some studies proposed correlations to predict two-phase flow pressure drop in microchannels. They were mostly based on Lockhart-Martinelli model with modification on C-coefficient, which was dependent on channel geometry, Reynolds number, surface tension, and so on. Others investigated the characteristics of flow boiling heat transfer in microchannels with respect to test parameters such as mass flux, heat flux, system pressure, and so on. The existing studies have not been fully satisfactory in providing consistent results about the pressure drop and the heat transfer in microchannels. Therefore, more in-depth studies should be done for understanding the fundamentals of the transport phenomena in the microchannels and giving the basic guidelines to design the micro devices.

• 복식
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• 제6권
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• pp.7-26
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• 1982

Investigation for industrial revolution has been recognized as an important issue of historical science, since industrial revolution itself was a historical moment in modern economic society and in the forming of modern capitalistic culture. If clothing culture had been developed in close relation to social culture. industrial revolution which gave a base for modern capitalistic culture, would be a birth of modern clothing as well as a moment for modernization of western clothing. As it takes for granted that industrial revolution, historical phenomenon is a developmental base of modern clothing culture. This study tried to enlighten the origin of modern clothing culture phenomenon with investigation of industrial revolution as a historical moment in modern clothing culture through documental study. Historian's point of view and method of studying are important when we investigate the clothing phenomenon. Although culture phenomenon of industrial revolution has been evaluated usually through socialogical aspect, studying for clothing culture phenomenon must be carried out on aethetical as well as well as sociological aspect, on account of dualism of clothing, as it is social and artistic nature. In 19th century, there were technical improvement, changing patterns of production, changing social relation and beginning of mass culture. At the same time clothing culture phenomenon was changed in relation to modern capitalistic society. The findings of the study could be summarized as follows. 1. Technical improvement in textile industry and fitting process brought about mechanization of clothing industry. 2. Appearance of popular clothing culture made it easy to spread to various classes of society. 3. Development of transportation system and communication channel made it internationalization of western clothing. 4. Recognition of importance in functional style of clothing. 5. The pursuit of modern aesthetics made rapid changing mode of clothing. Above distinctive features of modern clothing culture were derived from by-product of machinary culture, mass culture, internationalism, rapidly changing mode of various culture during industrial revolution. Industrial revolution was a change of the material world as well as in industry owing to machine advent, then the culture part that displayed directly these changes was the plastic arts of living that mould the material. The problem of clothing construction caused by industrial revolution was solved by pursuing the functional aesthetics. Clothing phenomenon as a process of value transfer participates mass culture in closs relation to general change of various culture caused by industrial revolution. Therefore western clothing gained the qualities of modern culture, condensed as function, and popularity in the process of modernization.

• 에너지공학
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• 제8권2호
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• pp.298-308
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• 1999

과냉각수조로 분사되는 증기의 직접접촉 응축특성을 알아보기 위하여 다섯 개의 수평 노즐에 대해 증기 질량유량과 수조 온도를 여러 가지로 변화시키면서 실험적 연구를 수행하였다. 증기응축현상을 육안관찰과 고속 비디오 카메라를 사용한 방법으로 분석한 결과, 안정된 증기제트인 경우 증기 질량속과 수조온도가 변화함에 따라 타원형 및 원추형 증기제트 형상이 나타나는 것을 관찰하였다. 증기제트 팽창비, 증기제트 길이 및 응축연전달계수를 구하였고, 증기 질량속, 수조온도 및 노즐 내경이 미치는 영향을 분석하였다. 증기제트 길이와 응축열전달계수를 증기 질량속 및 응축추진 포텐셜의 함수로 나타낸 상관식을 구하였다. 증기제트 내부와 주위 수조온도 분포를 구했으며 증기 질량속, 수조온도 및 노즐 내경이 미치는 영향을 분석하였다. 처깅, 천이처깅, 응축진동, 안정응축, 방울응축진동 및 간헐진동응축 등 여섯 가지 영역으로 구분된 응축 영역도를 작성하였다. 그 외, 수조 벽면에서의 동압을 측정하였고, 증기 질량속과 수조온도에 따라 변화하는 증기 응축모드와 동압과는 밀접한 연관성이 있음을 확인하였다.

• 무역상무연구
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• 제29권
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• pp.197-223
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• 2006

Uniform Computer Information Transactions Act (UCITA) is the first legislative attempt in the world that deals with transaction of digital information. This however gave rise to endless controversies and as of February 10, 2003, its life as the uniform law has expired. There are four kinds of relationships that UCITA regulates for the entities involved in information trading namely, 1) Relationship between licenser and licensee 2) The triangle relationship between dealers, end-user and publisher 3) Relationship between information right transferor and transferee 4) Relationship between financier, licenser and licensee. Amongst these, the most significant one is the triangle relationship amongst the publisher, commonly known as the licenser in the mass market, end-user and dealer. At the essence of the relationship is that the dealers is liable to refund the payment for the information regarding the end user if he/she does not agree with the publisher on the license of the common market. Looking at the relationship between license transferor and transferee, the transfer of license may be prohibited but the special contract must be conspicuously carried out. The relationship financier, licenser and licensee is unique to the United States and is rather unfamiliar to us. UCITA has been criticized for preferentially protecting the benefits of licensers especially when it comes to the specific regulations for the relationship. Therefore, it is not advisable to blindly accept UCITA regulations. However, UCITA does have components that we can utilize in formulating our own digital information trade regulations, save its proprietary nature as an American law and its preferential treatment for licensers.

• Nuclear Engineering and Technology
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• 제48권2호
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• pp.448-456
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• 2016

Severe accident scenarios in nuclear reactors, such as nuclear meltdown, reveal that an extremely hot molten core may fall into the nuclear reactor cavity and seriously affect the safety of the nuclear containment vessel due to the chain reaction caused by the reaction between the molten core and concrete. This paper reports on research focused on the type and amount of vapor produced during the reaction between a high-temperature molten core and concrete, as well as on the erosion rate of concrete and the heat transfer characteristics at its vicinity. This study identifies themass fraction and melting temperature as the most influential properties of concrete necessary for a safety analysis conducted in relation to the thermal interaction between the molten core and the basemat concrete. The types of concrete that are actually used in nuclear reactor cavities were investigated. The $H_2O$ content in concrete required for the computation of the relative amount of gases generated by the chemical reaction of the vapor, the quantity of $CO_2$ necessary for computing the cooling speed of the molten core, and the melting temperature of concrete are evaluated experimentally for the molten core-concrete interaction analysis.

• 한국항공우주학회지
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• 제34권12호
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• pp.59-66
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• 2006

하이브리드 로켓 연료의 연소율 향상을 위한 나선형 홈이 유동 특성에 미치는 영향을 규명하기 위하여 난류 증가와 선회 유동 발생에 대한 수치계산을 수행하였다. 나선형 튜브의 열전달 관계식을 이용하여 여러 형상의 나선형 홈이 있는 연료의 열전달 향상을 예측하였으며 연소율 측정값과 비교하여 상호 연관성을 확인하였다. 실험 결과와 열전달 향상 예측 값은 동일한 경향을 나타내더라도 수치는 큰 차이를 나타냈는데 이것은 연료가 연소하기 위하여 기화할 때 발생하는 분출속도가 존재하기 때문이다. 분출효과를 고려하여 RANS 계산을 수행한 결과, 난류에너지는 상당히 증가한 반면 선회 수는 조금 증가하는 결과를 보여 주었다. 그럼에도 불구하고 나선형 홈에 의한 난류 증가 또는 선회유동 생성은 연소율을 증가시키는 중요한 메커니즘임이 밝혀졌다. 그러나 분출로 인하여 난류에너지가 증가되어도 열전달 향상에 기여하지 못하는 것으로 확인되었는데 이것은 분출 속도가 표면의 경계층을 밀어내어 대류 열전달이 증가되는 것을 차단하기 때문인 것으로 밝혀졌다.

• 한국전산유체공학회지
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• 제13권4호
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• pp.50-57
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• 2008

The prediction of hydrate pellet decomposition characteristics is required to design the regasification process of GTS (gas to solid) technology, which is considered as an economic alternative for LNG technology to transport natural gas produced from small and stranded gas wells. Mathematical model based on the conservation principles, the phase equilibrium relation, equation of gas state and phase change kinetics was set up and numerical solution procedure employing volume averaged fixed grid formulation and extended enthalpy method are implemented. Initially, porous methane hydrate pellet is at uniform temperature and pressure within hydrate stable region. The pressure starts to decrease with a fixed rate down to the final pressure and is kept constant afterwards while the bounding surface of pellet is heated by convection. The predicted convective heat and mass transfer accompanied by the decomposed gas flow through hydrate/ice solid matrix is reported focused on the comparison of spherical and cylindrical pellets having the same effective radius.