• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.1
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• pp.57-65
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• 2003

As a compressed water is rapidly expanded through a nozzle, two-phase flow of vapor and liquid is formed in the nozzle due to the flash evaporation. In the present study, critical flow of two-phase fluids is analysized using an Isentropic-Homogeneous-Equilibrium model and a Leung model. Calculation results show that the choke of the two-phase flow can be two different types of continuous and discontinuous chokings. For the stagnation pressure below 10 Mpa it is found that the continuous choking, which is similar to the choking phenomenon of single-phase gas flow, is possible only when the degree of subcooling is less than 10K.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.292-297
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• 2001

This paper discusses the effect of varying LiBr solution circuits flow rates for a direct fired double effect commercial absorption chiller in the parallel flow configuration. The effects of solution flow rates have been investigated for generator, condenser, solution heat exchanger, absorber and evaporator. According to the result of this work, it was found that sensible heat rate of generator increases and refrigerant vapor generated in that decreases when inlet solution flow rate of that increases. As solution flow rate of absorber increases, the degree of superheat increases because of decreasing solution heat exchanger efficiency. The flashing vapor at the top of absorber increases in proportion to the degree of superheat whileas decreases cooling capacity inversely.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.334-343
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• 2003

The discharge gap clearly is to order and to promote the improvement of processing feature of die-sinking electro discharge machining(EDM). If creation carbon, which generated by Pyrolysis of EDM oil and processing pace power which is generated in between an electrode and a workpiece, are overproduced, they will lower the processing speed and roughness of the surface. Therefore, it is gone through an experiment and the flow analysis of EDM oil in order to improve the treatment of processing chips, which is an important problem by contriving a new flushing method. The condition of an electric discharge is not considered to be a progressing of processing. It is assumed that the flow of processing fluid is equal to the flow of processing chip, which is remaining in the discharge gap, and thus, analyzing then comparing with the data of the experiment and investigate its correlation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.105-109
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• 1996

The calculation of the total power required at the Continuous Extrusion Forming(CONFORM) has been performed by the theoretical analysis of three transformation regions(primary grip length and extrusion grip length, flashing). In this study, that was performed by five transformation regions(biting, upsetting, filling, extruding, flashing)and four transformation regions(biting, upsetting and filling, extruding, flashing) and then results of theoretical analyses were compared with experimental results. Results of analysis by four and five transformation regions than that of three transformation regions in the CONFORM showed in a good agreement with experimental results.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.272-277
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• 2005

The discharge gap clearly is to order and to promote the improvement of processing feature of die-sinking electro discharge machining(EDM). If creation carbon, which generated by pyrolysis of EDM oil and processing pace power which is generated in between an electrode and a workpiece, are overproduced, they will lower the processing speed and roughness of the surface. Therefore, it is gone through the .flow analysis of EDM oil in order to improve the treatment of processing chips, which is an important problem by contriving a new flushing method. The condition of an electric discharge is not considered to be a progressing of processing. It is assumed that the flow of processing fluid is equal to the flow of processing chip, which is remaining in the discharge gap, and analyzing its correlation.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2483-2488
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• 2008

To mitigate the effects of cavitation and flashing, several types of orifices have been installed in the pipeline of new nuclear power plants. To review the effects of wall thinning caused by flow-accelerated corrosion by the types of orifices, which are cone and plate, and the relation between flow behavior and local wall thinning, experiments and numerical analyses for the downstream pipe of two types of orifices were performed. The experimental results in terms of static pressure obtained for the experimental facilities were compared with those of three-dimensional (3D) numerical analyses using the FLUENT code. As the results of review of flow-accelerated corrosion effects based on the experiment and numerical analysis, it was identified that the orifice of cone-type can be comparatively mitigated the effects of cavitation and flashing, but can not be mitigated the effect of flow-accelerated corrosion.

• Broadcasting and Media Magazine
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• v.25 no.2
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• pp.17-26
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• 2020

최근 스마트폰에서의 증강현실, 미적 효과의 증대(예, 라이브 포커싱) 등의 어플리케이션을 제공하기 위해 모바일 기기에서의 3차원 공간 복원 기술에 대한 관심이 증가하고 있다. 소비자들의 요구에 발 맞춰 최근 스마트폰 제조사는 모든 플래그십 모델에 다중 카메라 및 뎁스 센서(거리 측정 센서)를 탑재하는 추세이다. 본 고에서는 모바일 폰에 탑재되고 있는 대표적인 세 축의 뎁스 추정(공간 복원) 방식에 대해 간단히 살펴보고, 최근 심층학습(Deep learning)의 등장으로 기술 발전의 새로운 국면에 접어 든 다중 시점 매칭(Multi-view stereo) 방법에 대해 소개하고자 한다. 심층 신경망이 재조명 받은 2012년 전까지 주류 연구 방향이었던 전통 기하학 기반의 방법에 대한 소개를 시작으로 심층 신경망기반의 방법론으로의 발전된 형태를 살펴본다. 또한, 신경망기반의 방법론은 크게 3 세대로 나누어 각 세대별 특징에 대해 자세히 살펴보고, 다양한 데이터에 대한 실험 결과를 통해 세대별 공간 복원 결과를 비교 분석한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.429-435
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• 2010

In approximately fifty utilities, including KHNP (Korea Hydro & Nuclear Power), CHECWORKS is used as a tool for predicting and managing the wall thinning of carbon steel piping; this wall thinning is caused by flow-accelerated corrosion (FAC). It is known that CHECWORKS is only applicable to predict the wall thinning of piping with large bores. When dealing with small-bore steel piping, FAC engineers measure the thickness of the susceptible area that is selected on the basis of the experience and judgment of the engineer. This paper proposes the application of CHECWORKS for the management of wall thinning of small-bore piping. Four small-bore pipelines of a domestic nuclear power plant were analyzed from the viewpoints of FAC and fluid dynamics by using CHECWORKS and FLUENT code. Depending on the engineer's skill, CHECWORKS can also be used for the management of wall thinning of small-bore piping.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1105-1110
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• 2011

Flow-accelerated corrosion (FAC) is a well-known phenomenon that may occur in piping and components. Most nuclear power plants have carbon-steel-pipe wall-thinning management programs in place to control FAC. However, various other erosion mechanisms may also occur in carbon-steel piping. The most common forms of erosion encountered (cavitation, flashing, Liquid Droplet Impingement Erosion (LDIE), and Solid Particle Erosion (SPE)), have caused wall thinning, leaks, and ruptures, and have resulted in unplanned shutdowns in utilities. In particular, the damage caused by LDIE is difficult to predict, and there has been no effort to protect piping from erosive damage. This paper presents an evaluation method for LDIE. It also includes the calculation results from prediction models, a review of the experimental results, and a comparison between the UT data in the damaged components and the results of the calculations and experiments.