• Nuclear Engineering and Technology
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• 제31권2호
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• pp.236-255
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• 1999

An improved mechanistic model was developed to predict a convective boiling critical heat flux (CHF) in the vertical round tubes with uniform heat fluxes. The CHF formula for subcooled and low quality boiling was derived from the local conservation equations of mass, energy and momentum, together with appropriate constitutive relations. The model is characterized by the momentum balance equation to determine the limiting transverse interchange of mass flux crossing the interface of wall bubbly layer and core by taking account of the convective shear effect due to the frictional drag on the wall-attached bubbles. Comparison between the present model predictions and experimental CHF data from several sources shows good agreement over a wide range of How conditions. The present model shows comparable prediction accuracy with the CHF look-up table of Groeneveld et al. Also the model correctly accounts for the effects of flow variables as well as geometry parameters.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.29-34
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• 2002

The heat of hydration of cement causes the internal temperature rise at early age, paticular in massive concrete structures. As the results of the temperature rise and restraint condition, the thermal stress may induce cracks in concrete. The prediction of the thermal stress is important in design and construction stages in order to control the cracks in mass concrete. It is poor economy to analysis for prediction of the thermal stress on each design or construction. In this study, the hydration heat and thermal stress analysis is performed by ABAQUS program, as a results of thermal analysis, the formula of size-placing depth relationship is proposed.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제25회 추계학술대회논문집
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• pp.323-326
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• 2005

본 연구에서는 연료 따른 End-Burning 하이브리드 추진 시스템의 연소 특성을 파악하기 위한 실험적 연구를 수행하였다. 연료로는 PMMA, PE를 사용하였으며 산화제는 기체 산소를 사용하였다. 연료의 후퇴율은 산화제 유량뿐만 아니라 연료의 열역학적 성질의 함수이다. 본 실험을 통하여 연료의 후퇴율이 산화제 유량과 물질전달계수인 B number로 표현된 경험식을 얻었다.

• Structural Engineering and Mechanics
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• 제25권2호
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• pp.181-200
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• 2007

A decoupling technique for simulating near-field wave motions in two-phase media is introduced in this paper. First, an equivalent but direct weighted residual method is presented in this paper to solve boundary value problems more explicitly. We applied the Green's theorem for integration by parts on the equivalent integral statement of the field governing equations and then introduced the Neumann conditions directly. Using this method and considering the precision requirement in wave motion simulation, a lumped-mass FEM for two-phase media with clear physical concepts and convenient implementation is derived. Then, considering the innate attenuation character of the wave in two-phase media, an attenuation parameter is introduced into Liao's Multi-Transmitting Formula (MTF) to simulate the attenuating outgoing wave in two-phase media. At last, two numerical experiments are presented and the numerical results are compared with the analytical ones demonstrating that the lumped-mass FEM and the generalized MTF introduced in this paper have good precision.

• 천문학회지
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• 제47권6호
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• pp.215-218
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• 2014

One-dimensional (1-D) microlens parallaxes can be combined with heliocentric lens-source relative proper motion measurements to derive the lens mass and distance, as suggested by Ghosh et al. (2004). Here I present the first mathematical anlysis of this procedure, which I show can be represented as a quadratic equation. Hence, it is formally subject to a two-fold degeneracy. I show that this degeneracy can be broken in many cases using the relatively crude 2-D parallax information that is often available for microlensing events. I also develop an explicit formula for the region of parameter space where it is more difficult to break this degeneracy. Although no mass/distance measurements have yet been made using this technique, it is likely to become quite common over the next decade.

• Food Science and Biotechnology
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• 제14권1호
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• pp.89-93
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• 2005

Squalene synthase (SQS) inhibitors were screened from various plants and food extracts. Effective SQS inhibitor was purified from fermented soybean paste using ethanol extraction, HP-20 column chromatography, ethyl acetate extraction, silica gel column chromatography, and crystallization. Through UV spectrometry, $^1H$ NMR, $^{13}C$ NMR, and mass spectrometry, SQS inhibitor was identified as daidzein with molecular mass of 254 and molecular formula of $C_{15}H_{10}O_4$. Daidzein showed $IC_{50}$ value of 50 nmol/L against SQS, confirming its potential as therapeutic agent for hypercholesterolemia.

• 대한조선학회지
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• 제20권1호
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• pp.29-33
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• 1983

The loading condition, of a ship, especially a multi-purpose cargo carrier, in service, is often changed. Then, the prediction of natural frequency changes is necessary to provide measures for prevention of ship vibrations. In this paper a simplified method for the above purpose is presented. The bases of the method are analytical solutions for the lateral vibrations of uniform Timoshenko beams carrying a concentrated mass and the Dunkerley's formula. In this method a ship in the standard ballast condition is reduced to a uniform Timoshenko beam having same system parameters as those of the midship section. To investigate the validity of the proposed method, numerical calculations are carried out for a 46,000 DWT bulk carrier and compared with detailed calculations based on the finite difference method. Even in cases those the cargoes in a hold, length of which is about 13% of the ship's length, are reduced to a concentrated mass, the proposed method gives results of several percent differences from the detailed calculations up to the six-noded mode.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1405-1407
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• 2000

This paper is on optimal design for DC substation capacity for Mass Transit System. Three factors are considered for the design i.e. substation arrangements, line configuration and substation power capacity. In this study, we discussed substation power capacity only. At first, DC-fed-traction system is introduced on an outline, a characteristics of train and fed network. Optimal design procedures is described, and modelling for DC-fed-traction system are presented. The circuit-solution method is presented by matrix formula. In order to simulate DC substation power capacity more closely to actual situations, we proposed the program.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제23권4호
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• pp.1059-1078
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• 2009

본 연구는 삼각형의 방접원에 관련된 다양한 대수적 성질을 탐구한 선행연구들의 확장으로, 방접원의 중심인 방심과 꼭짓점, 방심과 내심, 외심, 무게중심, 수심사이의 거리에 관련된 다양한 등식들을 탐구하였다. 특히 본 연구에서는 잘 알려지지 않은 이들 등식을 재발명 또는 발명하고, 등식들의 다양한 변형들을 제시하였으며, 중등학교 수학의 수준에서 이해될 수 있는 증명들을 제시하였다.

• 패션비즈니스
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• 제13권3호
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• pp.109-117
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• 2009

To set up the outstanding and scientific dyeing method in making the condensed liquid of pigment obtained from onion skins and the improved reliability, the following basic experiments were performed. The pigment was extracted in the distilled water at $70^{\circ}C$ and methanol at room temperature and then it was analyzed with LC/MS/MS system (Liquid Chomatography/Mass Spectroscopy/Mass Spectroscophy, LIQ Advantage Max, Thermo Finnigan, USA) for its pigmental characteristics. The unrefined silk and refined silk were dyed by making use of the derived pigment in such a way. The chromameter (CR-200, Minolta, Japan) was used to measure the change in surface color in textiles to be dyed by the extracting condition and the color difference ${\Delta}E$ was determined according to the color difference formula CIE LAB through measuring the psychometric lightness L* and chromaticity coordinates a* and b*.