• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 제38회 하계학술대회
• /
• pp.1059-1060
• /
• 2007

In this paper analysis of the characteristics in the three phase induction motor for the electric forklift truck is researched. There are two kinds of the Finite element analysis method. First thing is time domain analysis by the time transient method. Second thing is frequency domain analysis by method which assumes applied voltage and current sinusoidal. Especially in case of the characteristic studies, electromagnetic analysis is performed about each prototype motors. The obtained results are compared and the result of the test is examined. We could know characteristics of each prototypes and verify the design program of the motor through FEM. Finally this paper shows the factors of discord results of the analysis.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
• /
• pp.81-81
• /
• 2007

Chemical mechanical polishing (CMP) 공정은 deep 서브마이크론 집적회로의 다층배선구조률 실현하기 위해 inter-metal dielectric (IMD), inter-layer dielectric layers (ILD), pre-metal dielectric (PMD) 층과 같은 절연막 외에도 W, Al, Cu와 같은 금속층을 평탄화 하는데 효과적으로 사용되고 있으며, 다양한 소자 제작 및 새로운 물질 등에도 광범위하게 응용되고 있다. 하지만 Cu damascene 구조 제작으로 인한 CMP 응용 과정에서, 기계적으로 깨지기 쉬운 65 nm의 소자 이하의 구조에서 새로운 저유전상수인 low-k 물질의 도입으로 인해 낮은 하력의 기계적 연마가 필요하게 되었다. 본 논문에서는 전기화학적 기계적 연마 적용을 위해, I-V 특성 곡선을 이용하여 active, passive, transient, trans-passive 영역의 전기화학적 특성을 알아보았으며, Cu 막의 표면 형상을 알아보기 위해 scanning electron microscopy (SEM) 측정과 energy dispersive spectroscopy (EDS) 분석을 통해 금속 화학적 조성을 조사하였다.

• Nuclear Engineering and Technology
• /
• 제27권2호
• /
• pp.165-175
• /
• 1995

가압경수로의 과압보호계통은 가장 심각한 비정상 과도운전시 원자로냉각재계통의 압력을 설계압력의 110% 이내로 유지시킬 수 있는 충분한 용량으로 설계되어져야 한다. 본 연구에서는 ABB-CE 설계의 2825 MWt 가압경수로에 기존의 스프링 탑재형 가압기 안전밸브 대신 SEBIM-POSRV를 채택할 경우 과압보호 기능 수행의 가능성을 연구하였다. 과압보호 기능을 수행하기 위한 SEBIM POSRV의 크기 및 작동 설정치를 영광 3, 4호기의 과압보호 해석에 사용했던 LTC 전산코드를 이용한 분석을 통해서 결정했다. 분석 결과 monobloc SEBIM POSRV를 이용한 과압보호계통은 원자로냉각재계통의 압력을 설계 압력의 110% 이내로 유지시킴으로써 ABB-CE 형태의 2825 MWt급 가압경수로에서 과압보호 기능을 수행할 수 있음이 입증되었다.

• Nuclear Engineering and Technology
• /
• 제30권6호
• /
• pp.541-554
• /
• 1998

A computer code COSMOS has been developed based on the CARO-D5 for the thermal analysis of LWR UO$_2$ and MOX fuel rod under steady-state and transient operating conditions. The main purpose of the COSMOS, which considers high turnup characteristics such as thermal conductivity degradation with turnup and rim formation at the outer part of fuel pellet, is to calculate temperature profile across fuel pellet and fission gas release up to high burnup. A new mechanistic fission gas release model developed based on physical processes has been incorporated into the code. In addition, the features of MOX fuel such as change in themo-mechanical properties and the effect of microscopic heterogeneity on fission gas release have been also taken into account so that it can be applied to MOX fuel. Another important feature of the COSMOS is that it can analyze fuel segment refabricated from base irradiated fuel rods in commercial reactors. This feature makes it possible to analyze database obtained from international projects such as the MALDEN and RISO, many of which were collected from refabricated fuel segments. The capacity of the COSMOS has been tested with some number of experimental results obtained from the HALDEN, RISO and FIGARO programs. Comparison with the measured data indicates that, although the COSMOS gives reasonable agreement, the current models need to be improved. This work is being performed using database available from the OECD/NEA.

• Nuclear Engineering and Technology
• /
• 제43권6호
• /
• pp.531-546
• /
• 2011

The backward differentiation formula (BDF) method is applied to a three-dimensional reactor kinetics calculation for efficient yet accurate transient analysis with adaptive time step control. The coarse mesh finite difference (CMFD) formulation is used for an efficient implementation of the BDF method that does not require excessive memory to store old information from previous time steps. An iterative scheme to update the nodal coupling coefficients through higher order local nodal solutions is established in order to make it possible to store only node average fluxes of the previous five time points. An adaptive time step control method is derived using two order solutions, the fifth and the fourth order BDF solutions, which provide an estimate of the solution error at the current time point. The performance of the BDF- and CMFD-based spatial kinetics calculation and the adaptive time step control scheme is examined with the NEACRP control rod ejection and rod withdrawal benchmark problems. The accuracy is first assessed by comparing the BDF-based results with those of the Crank-Nicholson method with an exponential transform. The effectiveness of the adaptive time step control is then assessed in terms of the possible computing time reduction in producing sufficiently accurate solutions that meet the desired solution fidelity.

• Nuclear Engineering and Technology
• /
• 제41권6호
• /
• pp.797-806
• /
• 2009

The Multichannel Analyzer for Transient and steady-state in Rod Array - Liquid Metal Reactor for Flow Blockage analysis (MATRA-LMR-FB) code for the analysis of a subchannel blockage has been developed and evaluated through several experiments. The current version of the code is improved here by the implementation of a distributed resistance model which accurately considers the effect of flow resistance on wire spacers, by the addition of a turbulent mixing model, and by the application of a hybrid scheme for low flow regions. Validation calculations for the MATRA-LMR-FB code were performed for Oak Ridge National Laboratory (ORNL) 19-pin tests with wire spacers and Karlsruhe 169-pin tests with grid spacers. The analysis of the ORNL 19-pin tests conducted using the code reveals that the code has sufficient predictive accuracy, within a range of 5 $^{\circ}C$, for the experimental data with a blockage. As for the results of the analyses, the standard deviation for the Karlsruhe 169-pin tests, 0.316, was larger than the standard deviation for the ORNL 19-pin tests, 0.047.

• 한국가시화정보학회:학술대회논문집
• /
• 한국가시화정보학회 2002년도 추계학술대회 논문집
• /
• pp.39-42
• /
• 2002

In the current study, characteristics of the laser-induced plasma were investigated in a gas filled chamber or in a gas jet by using a relatively low intensity laser $(I\;\leq\;5\;\times\;10^{12}\;W/cm^2)$. Temporal evolutions of the produced plasma were measured using the shadow visualization and the shock wave propagation as well as the electron density profiles in the plasma channel was measured using the Mach-Zehnder interferometry. Experimental results such as the structure of the produced plasma, shock propagation speed $(V_s)$, electron density profiles $(n_e)$, and the electron temperature $(T_e)$ are discussed in this study. Since the diagnostic laser pulse occurs over short time intervals compared to the hydrodynamic time scales of expanding plasma or a gas jet, all the transient motion occurring during the measurement is assumed to be essentially frozen. Therefore, temporally well-resolved quantitative measurements were possible in this study.

• 한국정밀공학회지
• /
• 제25권5호
• /
• pp.112-120
• /
• 2008

This study has been conducted to investigate the characteristics of flow field and discharge valve motion in a rotary compressor. In this study, a transient three-dimensional numerical analysis using FSI(Fluid-Structure Interaction) model has been employed to analyze the interaction between the discharge valve and the refrigerants in the rotary compressor. It has been observed that two peaks have appeared in the displacement of the discharge valve. The maximum displacement of the discharge valve has been found to be located at the second peak. Also, the input pressure of the refrigerants has been compared with the pressures of the muffler passage and the compressor outlet in the rotary compressor. The pressure has decreased along the pathway in the rotary compressor. And the volume flow rates obtained from the current numerical study have been compared with the experiment at data to verify the validity of the present numerical study. This study may supply the fundamental data for the design of rotary compressors.

• 항공우주산업기술동향
• /
• 제8권1호
• /
• pp.131-139
• /
• 2010

1903년 항공기가 개발된 이래 항공전자(Avionics)는 항공기의 발달과 함께 발전해 왔다. 역사적으로 1910년대 무선통신을 시작으로 1920년대의 무선항법, 1930년대의 자동조종 도입 등 꾸준히 발달해 왔으며 GPS의 등장과 1979년 MD-80의 전자식 조종실 시현장치(1)의 등장으로 획기적인 전환을 이루게 된다. 현대 항공기에서 항공전자의 위치는 컴퓨터 이용 기술로 비행 안전성, 쾌적성 등의 측면에서 큰 비중을 차지하고 있다. 항공전자의 발달과 더불어 인증기술도 연동하여 개발이 되고 있다. 이 글에서는 최근 개발된 항공전자 인증기술을 소개한다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
• /
• pp.499-503
• /
• 2009

In this study, the dynamic characteristic of a contact wire and pantograph suppling electrical power to high-speed trains are investigated from an electrical response point of view. To analysis power line disturbance by induced contact loss phenomenon for high speed operation, a hardware Simulator which considered contact loss between contact wire and the pantograph as well as contact wire deviation is developed. It is confirmed that a contact wire and pantograph model are necessary for studying the dynamic behavior of the pantograph system. One of the most important needs accompanied by increasing the speed of high-speed train is reduced that an arc phenomenon by loss of contact brings out EMI. In case of a high-speed train using electrical power, as comparison with diesel rolling stock, PLD(Power Line Disturbance) such as harmonic, transient voltage and current, EMI, dummy signal injection etc usually occurs. Throughout experiment, it is verified that an arc phenomenon is brought out for simulator operation and consequently conducted noise is flowed in electric circuit by power line disturbance.