• 마이크로전자및패키징학회지
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• 제20권4호
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• pp.75-79
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• 2013

A power distribution network (PDN) is a network that provides connection between the voltage source supply and the power/ground terminals of a microprocessor chip. It consists of a voltage regulator module, a printed circuit board, a package substrate, a microprocessor chip as well as decoupling capacitors. For power integrity analysis, the board and package layouts have to be transformed into an electrical network of resistor, inductor and capacitor components which may be expressed using the S-parameters models. This modeling process generally takes from several hours up to a few days for a complete board or package layout. When the board and package layouts change, they need to be re-extracted and the S-parameters models also need to be re-generated for power integrity assessment. This not only consumes a lot of resources such as time and manpower, the task of PDN modeling is also tedious and mundane. In this paper, a block-based PDN modeling is proposed. Here, the board or package layout is partitioned into sub-blocks and each of them is modeled independently. In the event of a change in power rails routing, only the affected sub-blocks will be reextracted and re-modeled. Simulation results show that the proposed block-based PDN modeling not only can save at least 75% of processing time but it can, at the same time, keep the modeling accuracy on par with the traditional PDN modeling methodology.

• 정보통신설비학회논문지
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• 제2권1호
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• pp.37-44
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• 2003

In this paper, a technique to estimate EMI source distribution on a digital circuit board ir introduced. A sensitivity analysis method is applied to reconstruct the source distribution from measured electric field data. Results from a single-layer measurement and a double-layer measurement are compared. It will be shown, from the simulation, that the use of sensitivity analysis for the EMI source reconstruction problem can be a very promising technique.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2002년도 하계학술대회 및 세미나
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• pp.6-9
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• 2002

In this paper a technique to estimate EMI source distribution on a digital circuit board is introduced. A sensitivity analysis method is applied to reconstruct the source distribution from measured electric field data. Results from a single-layer measurement and a double-layer measurement are compared. It will be shown, from the simulation, that the use of sensitivity analysis for the EMI source reconstruction problem can be a very promising technique.

• Journal of Welding and Joining
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• 제22권2호
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• pp.69-77
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• 2004

The Gaussian heat source has been widely used to simulate the heat flux of the welding we, and applied to calculating the temperature distribution of a workpiece. The conventional two-dimensional Gaussian heat source for the GMAW is modified in this work by decomposing the arc heat into heats of the cathode and metal transfer. The efficiency and effective arc radius of each heat source are determined analytically for the free-flight mode such as the globular and spray modes. The temperature distribution and weld geometry are calculated using the finite element method, and distribution of the drop heat is found to have significant effects on the penetration. The predicted results show good agreements with the available experimental results, especially with the penetration.

• 한국표면공학회지
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• 제48권4호
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• pp.179-184
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• 2015

Quadrupole Mass Spectrometers (QMS) is a very useful tool in vacuum process diagnosis. Tungsten filament based ion sources are vulnerable to contamination from process gas monitoring. Common symptoms of quadrupole mass spectrometer malfunction is appearance of unwanted contaminant mass peaks or no detection of any ion peaks. We disassembled used quadrupole mass spectrometer and found out black insulating deposits on inside of ion source parts. Five steps of cleaning procedure were applied and almost full restoration of functions were confirmed in two types of closed ion source quadrupole mass spectrometer. By using a numerical modeling (CFD-ACE+) technique, the electric potential profile of ion source with/without insulating deposit was calculated and showed the possibility of quadrupole mass spectrometer malfunction by the deterioration of designed potential profile inside the ion source.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.194-198
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• 2006

In this study, numerical modeling was performed to analyze air flow including radiation heat transfer inside a small chamber. Characteristics of heat transfer between source plate and target through glass are investigated for various surface temperature of heat source plate with buoyancy effect due to gravity force. Conduction heat transfer through the glass is considered and heat source plate is assumed to be a black body. Target surface temperature is largely affected by the radiation heat transfer. It can also be seen that as the source temperature increases target surface is dominated by radiation rather than convective heat transfer by air.

• Current Optics and Photonics
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• 제4권6호
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• pp.461-465
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• 2020

A dual-mode laser terahertz source consisting of two in-line distributed Bragg reflector (DBR) laser diodes (LD) is proposed. It is less susceptible to residual reflections from facets than an in-line dual-mode distributed feedback (DFB) LD. The characteristics of the proposed terahertz source are theoretically investigated using a split-step time-domain simulation. It is shown that terahertz waves of frequencies from 385 GHz to 1725 GHz can be generated by appropriate thermal tuning of two DBR LDs. The dual-mode DBR LD terahertz source exhibits good spectral quality for residual facet reflectivity below 0.02, but facet reflectivity of the in-line dual-mode DFB LD terahertz source should be below 0.002 to provide similar spectral quality.

• 한국항공우주학회지
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• 제39권10호
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• pp.959-965
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• 2011

본 논문에서는 소형 무인기의 전기추진 시스템에 대한 모델링 및 전력 시뮬레이션에 관하여 기술하였다. 각 전력원 모델링 및 시뮬레이션을 위해 Matlab/Simulink를 사용하였고, 연료전지와 배터리를 주 전력원으로 사용하는 200 W급 전기추진 시스템에 대하여 4시간 30분의 비행 시험결과와 시뮬레이션 한 결과를 비교하였다. 그 결과, 시뮬레이션은 각 전력원의 성능 및 동특성을 적절히 모사하였고, 이를 통해 다른 급의 전기추진 시스템에 대한 전력특성변화를 예측하는 도구로 활용 가능함을 알 수 있었다.

• 한국정보통신학회논문지
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• 제6권3호
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• pp.416-420
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• 2002

네트워크 트래픽의 연구 동향은 LAN, WAN 및 VBR 비디오 트래픽이 통계학적으로 자기 유사과정에 의해 더욱 더 잘 모델링화 된다는 사실을 입증하고 있다. 이것은 기존의 단기간 의존성만을 고려한 포아손 과정에 비해 다른 이론적 특성을 가진다. 즉 광범위한 시계열상에서 aggregation의 정도가 변하더라도 통계학적으로 동일한 특성을 지니게 된다는 것이다. 본 논문에서는 이러한 자기유사과정을 갖는 데이터를 실시간 운영중인 네트워크로부터 측정하여 트래픽을 모델링하고, 비교분석하므로서 다양한 데이터를 지원하는 초고속 네트워크의 성능분석에 적용할 수 있으리라 여겨진다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.32-35
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• 2006

The validation of a groundwater source heat pump system installation site is estimated by bydrogeothermic model ing. The hydraulic characteristics of the aquifer system is evaluated from pumping and recovery tests. In addition, the temperature distribution by the pumping and the injection of groundwater, and water level fluctuations are simulated by numerical modeling. The total cooling and heating load for the building is designed as 120RT(refrigeration ton) and the ground water source heat pump system covers 50RT as a subsidiary system The scenario of heat pump operation is organized as pumping and inject ion of groundwater that is performed for 8 hours per day in cooling mode for 90 days during the summer season The heat transfer by the injected warm water is limited near the inject ion wells in the simulated temperature distribution. The reason is that the given operation time is too short to expect broad thermal diffusion in large volume of the aquifer in the simulation time The simulated groundwater level and temperature distribution can be used as important data to develope an energy effective pumping and injection well system. Also it will be very useful to evaluate the hydraulic capacity of a target groundwater reservoir.