• 한국전산유체공학회지
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• 제21권4호
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• pp.71-77
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• 2016

The CUPID code is a transient, three-dimensional, two-fluid, thermal-hydraulic code designed for a component-scale analysis of nuclear reactor components. The primary objective of this study is to assess the applicability of CUPID to single-phase turbulent flow analyses of $2{\times}2$ rod bundle subchannel. The bulk velocity at the inlet varies from 1.0 m/s up to 2.0 m/s which is equivalent to the fully turbulent flow with the range of Re=12,500 to 25,000. Adiabatic single-phase flow is assumed. The velocity profile at the exit region is quantitatively compared with both experimental measurement and commercial CFD tool. Three different boundary conditions are simulated and quantitatively compared each other. The calculation results of CUPID code shows a good agreement with the experimental data. It is concluded that the CUPID code has capability to reproduce the turbulent flow behavior for the $2{\times}2$ rod bundle geometry.

• JSTS:Journal of Semiconductor Technology and Science
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• 제6권4호
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• pp.234-239
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• 2006

In the past decade, several tools have been developed to automate the floating-point to fixed-point conversion for DSP systems. In the conversion process, a number of scaling shifts are introduced, and they inevitably alter the original code sequence. Recently, we have observed that a compiler can often be adversely affected by this alteration, and consequently fails to generate efficient machine code for its target processor. In this paper, we present an optimization technique that safely migrates scaling shifts to other places within the code so that the compiler can produce better-quality code. We consider our technique to be safe in that it does not introduce new overflows, yet preserving the original SQNR. The experiments on a commercial fixed-point DSP processor exhibit that our technique is effective enough to achieve tangible improvement on code size and speed for a set of benchmarks.

• 항공우주정책ㆍ법학회지
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• 제24권2호
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• pp.19-45
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• 2009

우리나라는 항공운송에 관한 사법적 법률관계를 규율하는 법률이 제정되어 있지 아니하므로 항공화물운송을 둘러싼 분쟁을 오로지 항공사의 항공운송약관에 의해 해결을 시도하여 왔다. 그러나 국내항공운송에서 화주의 권익을 보호하고 운송계약당사자의 권리의무를 명확히 하기 위해 항공운송에 관한 법률을 제정할 필요가 있는 것이다. 국제항공운송에 있어서는 1999년에 채택된 몬트리올 협약을 우리나라가 가입하여 2007년 12월 29일 발효되어 있으므로 국제항공운송에 관련된 분쟁에는 몬트리올 협약이 적용된다. 법무부는 2008년에 상법 제6편 항공운송편 제정안을 마련하여 공청회를 거쳐 2008년 12월 31일 국회 제출되어 현재 심의 중에 있다. 상법 항공운송편 제정안은 기본적으로 몬트리올 협약을 근간으로 하고 있으며, 상법의 육상운송 및 해상운송의 제 규정과 위배됨이 없도록 제정목표를 두어 총 3개장 45개 조문 및 부칙으로 구성되어 있다. 상법 항공운송편 제정안가운데 특히 항공화물운송인의 책임에 관한 규정으로 운송인의 책임원인, 비계약적 청구에 적용, 운송인의 책임한도, 운송인의 책임감면, 운송인의 책임소멸, 운송물의 멸실 훼손 등의 통지, 운송인의 사용인.대리인의 책임, 실제 운송인의 책임, 순차운송인의 책임 등에 관한 규정이 있다. 이와 같은 항공화물운송인의 책임에 관한 규정가운데 쟁점사항으로는, 항공운송편 제정안 제913조제1항 단서의 운송인의 면책사유로 몬트리올 협약 제18조제2항에 규정되어 있지 아니한 폭동, 내란, 검역 등이 추가되어 있다는 점, 상법 제121조 및 제147조는 육상운송 및 육상운송주선의 경우 운송인의 책임에 관하여 악의의 경우를 제외하고 1년의 단기 제척기간을 규정하고 있는 반면에 항공운송편 제정안 제902조는 항공운송인의 악의가 있든 없든 2년의 제척기간을 규정하고 있는 점, 항공운송편 제정안 제899조 제3항은 화물운송의 경우 항공운송인의 사용인이나 대리인에게 고의 또는 인식있는 무모한 작위 또는 부작위가 있는 경우에도 사용인이나 대리인인 운송인이 주장할 수 있는 항변과 책임제한을 원용할 수 있다는 점들을 들수 있다. 결론적으로, 상법 항공운송편 제정안에는 당사자 간의 분쟁해결 및 운송인의 책임분산에 관한 규정이 있지 아니한 바 몬트리올 협약 제34조의 중재 및 제50조의 보험에 관한 규정을 수용하여 포함시키는 것이 바람직할 것이다. 또한 상법 항공운송편 제정안이 조속히 국회에서 통과되어 시행될 경우 운송인 등과 화주 간에 화물의 멸실, 훼손 또는 연착으로 인한 손해배상책임에 관한 분쟁을 원활하고 공평하게 해결하는데 기여할 것이다.

• 한국연소학회지
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• 제15권3호
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• pp.15-24
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• 2010

The purpose of this study is to assess approaches to modeling coal gasification and combustion in general purpose CFD codes. Coal gasification and combustion involve complex multiphase flows and chemical reactions with strong influences of turbulence and radiation. CFD codes would treat coal particles as a discrete phase and gas species are considered as a continuous phase. An approach to modeling coal reaction in $FLUENT^{(R)}$, selected in this study as a typical commercial CFD code, was evaluated including its devolatilization, gas phase reactions, and char oxidation, turbulence, and radiation submodels. CFD studies in the literature were reviewed to show the uncertainties and limitations of the results. Therefore, the CFD analysis gives useful information, but the results should be carefully interpreted based on understandings on the uncertainties associated with the modelings of coal gasification and combustion.

• 한국해양공학회지
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• 제19권4호
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• pp.15-20
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• 2005

This paper presented the development of a new experimental and numerical technique for the investigation of slamming impact. The in-house code was developed, based on the boundary element method. The application of commercial code was attempted using FLUENT. Pneumatic cylinder and LM-guide were introduced to closely simulate the free fall phenomenon. It was demonstrated that the proposed experimental and numerical studies can be useful tools in investigating slamming phenomenon.

• 대한기계학회논문집A
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• 제27권3호
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• pp.409-415
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• 2003

The purpose of this paper is to develop the 2-Dim Lagrangian Hydrocode for the analysis of large deformations of solids with implementation of the contact algorithm. First, th e governing equations are discretized into a system of algebraic equations. For more accurate and robust contact force computation. the defense node contact algorithm was adopted and implemented. For the verification of the code developed, two cases are carried out; the Taylor-Impact test and two bodies impact. The von -Mises criterion is implemented into the code with the Shock equation of state. The simulation results show a good agreement compared with the published experimental data and results from the commercial code. It is necessary to implement several material models and failure models for applications to different impact and penetration problems.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.508-512
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• 1997

Design sensitivity analysis of Eigen Problem give systematic design improvement information for noise and vibration of a system. Based on reliable results form commercial FE code(UAI/NASTRAN), three computational procedures for design sensitivity analysis of eigen problem are suggested. Those methods are finite difference,design sensitivity analysis using external module and design sensitivity analysis running with NASTRAN. To verify the suggested methods, a numerical example is given and these results are compared with the results from UAI/NASTRAN eigen sensitivity option. We can conclude that design sensitivity coefficient of eigen proplems can be computed outside of the FE code as easy as inside of the FE code.

• Nuclear Engineering and Technology
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• 제47권4호
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• pp.424-433
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• 2015

The operating characteristics of hydrogen iodide (HI) decomposition for hydrogen production were investigated using the commercial computational fluid dynamics code, and various factors, such as hydrogen production, heat of reaction, and temperature distribution, were studied to compare device performance with that expected for device development. Hydrogen production increased with an increase of the surface-to-volume (STV) ratio. With an increase of hydrogen production, the reaction heat increased. The internal pressure and velocity of the HI decomposer were estimated through pressure drop and reducing velocity from the preheating zone. The mass of $H_2O$ was independent of the STV ratio, whereas that of HI decreased with increasing STV ratio.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.866-872
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• 2000

Superplastic forming processes by characteristic of low flow stress and high elongation have advantages to reducing on production cost and weight because of the product of complex form could be made in one part. However superplastically termed part has a characteristic of non-uniform thickness distribution along forming direction. Especially. since the thickness distribution affects on mechanical properties of product. the uniform thickness is very important. There are two solution procedure of implicit and explicit procedure to analyze the superplastic forming. In this study to analyze the thickness distribution two kinds of commercial programs of DEFORM and PAM-STAMP which implicit and explicit code are used respectly. The results from the two Programs were compared with eath other As a result implicit code were more suitable than explicit code for superplastic forming analysis.

• 한국연소학회지
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• 제11권2호
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• pp.28-36
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• 2006

A constant volume combustion chamber was used to investigate the combustion characteristics. of homogeneous charge of methane-air mixture under various initial pressure, equivalence ratio and ignition times. The constant volume combustion chamber(CVCC) mostly has been studied by the experiments of visualization until now. So it is needed the numerical analysis of fluid and combustion characteristics in chamber by the more detail simulation. In this paper, the numerical analysis is tried to approach basically the homogeneous charge combustion phenomena under the various conditions, and the combustion phenomena in chamber is numerically analyzed by the commercial FIRE code. As a results, the combustion phenomena which were mean temperature, OH radical and reaction rate in chamber were investigated and it showed that the smallest flame growth occurs for the lean state and the increase of initial charged pressure condition due to the reduced OH radical.