• Journal of the Korean Chemical Society
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• v.40 no.6
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• pp.409-414
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• 1996

The limit of applicability of Navier-Stokes equation to stationary plane shock-waves is examined by using the principle of minimum entropy production of linear irreversible thermodynamics. In order to obtain analytic results, the equation is linearized near the equilibrium of downstream. Results show that the solution of Navier-Stokes equation which fits the boundary condition of far downstream flow is consistent with the thermodynamic requirement within the first order when the solution is expanded around the M=1, where M is the Mach number of upstream speed.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.3
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• pp.15-22
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• 2018

This study refers to the composting of DDM Environmental Resource Center, which is operating abnormally in the food waste public-resource facilities that are operating nationwide, in accordance with the initial operating conditions. Similar process cases were investigated to examine issues concerning unusual composting facilities in DDM environmental resource centers and to analyse the causes of the issues. In addition, several improvement measures and alternatives for converting abnormal driving facilities into normal driving facilities may be proposed, and major abnormal driver provisions that are highlighted as issues during field application may be resolved.

• Journal of the Korean Society of Propulsion Engineers
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• v.6 no.2
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• pp.75-84
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• 2002

A numerical analysis of unsteady motion in solid rocket motors with a nozzle has been conducted. The numerical formulation including modified $\kappa$-$\varepsilon$ turbulence model treats the complete conservation equation for the gas phase and the one-dimensional equations in the radial direction for the condensed phase. A fully coupled implicit scheme based on a dual time-stepping integration algorithm has been adopted to solve the governing equations. After obtaining a steady state solution, pulse and periodic oscillations of pressure are imposed at the head-end to simulate acoustic oscillations of a travelling-wave motion in the combustion chamber. Various steady and unsteady state features in the combustion chamber of a rocket motor has been analyzed as results of numerical calculations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.815-821
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• 2013

The efficiency and lifetime of a polymer electrolyte membrane fuel cell (PEMFC) system is critically affected by the humidity of the incoming gas, which should be maintained properly under normal operating conditions. Typically, the incoming gas of a fuel cell is humidified by an external humidifier, but few studies have reported on the device characteristics. In this study, a laboratory-scale planar membrane humidifier is designed to investigate the characteristics of water transport through a hydrophilic membrane. The planar membrane humidifier is immersed in a constant temperature bath to isolate the humidifier from the effect of temperature variations. The mass transfer capability of the hydrophilic membrane is first examined under isothermal conditions. Then, the mass transfer capability is investigated under various conditions. The results show that water transport in the hydrophilic membrane is significantly affected by the flow rate, operating temperature, operating pressure, and flow arrangement.

• Proceedings of the Korean Fiber Society Conference
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• 1998.04a
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• pp.140-143
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• 1998

고분자 가공에서의 실제 공정 조건인 대변형하에서의 가공원액(고분자용융체 또는 농후용액)의 응답특성은 완제품의 기계적 또는 물리적 성질에 큰 영향을 미친다. 그러므로 고분자 액체의 유변학적 성질파악이 중요하며, 그 측정방법은 크게 정상전단실험과 동적전단실험으로 대별할 수 있다. 그러나 정상전달실험시에는 높은 전단속도하에서의 전단가열과 동시에 시료분해가 발생할 수 있다.(중략)

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.339-343
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• 1995

PWR 사용후핵연료 집합체를 운반할 수 있는 수송용기를 개발하기 위하여 단면이 수송용기의 실제 크기인 slice 모델을 사용하여 법규에서 규정하고 있는 정상조건인 주변온도 38$^{\circ}C$에서 냉각 매체로 nitrogen 과 helium 인 경우에 대하여 열시험을 수행하여 수송용기의 열전달 특성 및 핵연료봉의 건전성을 평가하였다. 열시험결과 내부핵연봉의 최대 은도는 각각 448$^{\circ}C$ 와 416$^{\circ}C$로 측정되었다. 이 값들은 핵연료봉의 건전성 유지에 필요한 허용치 이내 만족하는 것으로 수송 용기의 열전달성능이 우수함을 입증하는 것이다.

• Proceedings of the KSLP Conference
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• 1996.11a
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• pp.92-92
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• 1996

비디오스트로보스코피 화상의 정량화를 통한 glottal cycle의 객관적인 평가는 여러 질환의 감별 및 치료전후의 결과를 비교하는데 중요한 역할을 담당할 수 있으리라 사려되나 아직은 정상 발성시나 병적인 조건에서의 참고치나 그 의미에 대하여 보고된 경우는 흔치 않은 실정이다. 이에 저자들은 정상성인을 대상으로 발성의 주파수와 강도의 변화에 따른 glottal cycle의 변화를 정량화 함으로써 추후 연구나 임상적용 둥의 기본자료로서 활용하고자 하였다. (중략)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.156-156
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• 2003

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.543-544
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• 2010

• Proceedings of the Korean Nuclear Society Conference
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• 2002.10a
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• pp.310.1-310
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• 2002