• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.369-376
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• 2000

Parameters that represent the characteristic of consolidation have been determined by the oedometer tests. They are varied by the process of sampling and transportation, accuracy of apparatus, process of sample trimming and the skill of engineers. Also, it is difficult to grasp what factor exert a influence on the parameters. In this study, Slurry Rowe Cell Tests were peformed to evaluate the disturbance. Using the plot of e - log p which obtained from Rowe Cell test results, we compared the swelling indexes at the stress relief and the last loading stage. With that result, we tried to presume the disturbance of the 330 oedometer tests. The plot of compression-swelling index at the stress relief considerably scattered but at the last step of load shows a correlations between them. And the plot of depth-p$\sub$c/ shows a correlation with the different swelling indexes, but not in the LL-p$\sub$c/. Consequently, it is considered that the disturbance of the consolidation tests can be presumed by the comparison of the difference of swelling index.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.678-683
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• 2004

The most popular consolidation tester is a standard consolidatiion tester, which performs consolidation using the step load weight. However this apparatus is used to obtain only the vertical consolidation coefficient. Therefore the purpose of this study is to develope the horizontal consolidation cell for a horizaontal consolidation coefficient. Various size of tests have been peroformed to investigate the effect of scale effect. From the test results, it has turned out that this horizontal consolidation cell has a good function for a horizontal consolidation coefficient.

• Journal of the Korean Ceramic Society
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• v.38 no.6
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• pp.499-505
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• 2001

The behaviour of ionic compound crystals under combined chemical and externally applied electrical potential gradients is discussed. Firstly, a systematic overview is given. Then a formal analysis follows. The transport equations of the ions and the electric defects predict that even with reversible electrodes demixing, and in particular decomposition of the compound will occur if the applied d.c. current density is sufficiently high. These predictions are illustrated by appropriate experiments. With the help of the solid solution (Me, Fe)O, where Fe-ions are the dilute species, we investigate experimentally the behaviour of a ternary ionic crystal under a d.c. electric current load. All the compounds were placed in a galvanic cell, and the internal reactions which then could be observed were driven by the electric field in this cell. In addition, we discuss the influence of the electric field on the classical solid state reaction AX+BX=ABX$_2$, if again the reaction couple is placed in a galvanic cell.

• Journal of the Korean Ceramic Society
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• v.47 no.1
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• pp.1-7
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• 2010

Solid oxide fuel cells (SOFCs) have been under development for a variety of power generation applications. Power system sizes considered range from small watt-size units (e.g., 50-W portable devices) to very large multi-megawatt systems (e.g., 500-MW base load power plants). Because of the reversibility of its operation, the SOFC has also been developed to operate under reverse or electrolysis mode for hydrogen production from steam (In this case, the cell is referred to as solid oxide electrolysis cell or SOEC.). Potential applications for the SOEC include on-site and large-scale hydrogen production. One critical requirement for practical uses of these systems is long-term performance stability under specified operating conditions. Intrinsic material properties and operating environments can have significant effects on cell performance stability, thus performance degradation rate. This paper discusses potential applications of the SOFC/SOEC, technological status and current research and development (R&D) direction, and certain aspects of long-term performance degradation in the operation of SOFCs/SOECs for power generation/hydrogen production.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.203-203
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• 2010

The proton exchange membrane fuel cell (PEMFC) is different from the normal power supply, and it is a nonlinear, multi-input, strong coupling, the complex dynamic system with large time delay. At present, many studies on the content of the fuel cell fuel cells focus on a static process, this paper analyzed in subsequent sections of the process of fuel cell dynamic response time of transition, and then it found the method to reduce the response time during the process of load change to ensure that the stability of output power.

• The Magazine of the IEIE
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• v.24 no.6
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• pp.38-49
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• 1997

0.4mm Resign Rule의 Super Low Power Dissipation, Low Voltage. Operation-5- Full CMOS SRAM Cell을 개발하였다. Retrograde Well과 PSL(Poly Spacer LOCOS) Isolation 공정을 사용하여 1.76mm의 n+/p+ Isolation을 구현하였으며 Ti/TiN Local Interconnection을 사용하여 Polycide수준의 Rs와 작은 Contact저항을 확보하였다. p-well내의 Boron이 Field oxide에 침적되어 n+/n-well Isolation이 취약해짐을 Simulation을 통해 확인할 수 있었으며, 기생 Lateral NPN Bipolar Transistor의 Latch Up 특성이 취약해 지는 n+/n-wellslze는 0.57mm이고, 기생 Vertical PNP Bipolar Transistor는 p+/p-well size 0.52mm까지 안정적인 Current Gain을 유지함을 알 수 있었다. Ti/TiN Local Interconnection의 Rs를 Polycide 수준으로 낮추는 것은 TiN deco시 Power를 증가시키고 Pressure를 감소시킴으로써 실현할 수 있었다. Static Noise Margin분석을 통해 Vcc 0.6V에서도 Cell의 동작 Margin이 있음을 확인할 수 있었으며, Load Device의 큰 전류로 Soft Error를 개선할수 있었다. 본 공정으로 제조한 1M Full CMOS SRAM에서 Low Vcc margin 1.0V, Stand-by current 1mA이하(Vcc=3.7V, 85℃기준) 를 얻을 수 있었다.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.413-415
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• 1997

The solar cell has an optimum operating point to be able to get maximum power. To obtain maximum power from Photovoltaic array, potovolt aic power syste usually requres maximum power point tracking controller. The output characteristics of solar cell are nonlinear, and these characteristics vary with load solar insolation, solar cell temperature. Therefore the tracking control of maximum power point is the complicated problem. This paper presents power characteristics of residential Photovoltaic system applying a quck-boost conversion system.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1170-1171
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• 2008

Microsources supply high quality power from 1kW to a matter of MW with higher reliability and energy efficiency than the existing large power facilities. In this paper, we designed dynamic modeling of Microturbine and Fuel cell being worthy as a small distributed energy source. Using EMTP we designed the dynamic modeling and confirmed characteristics of steady-state and dynamic analysis. In this paper, we designed dynamic modeling of Microturbine and Fuel cell being worthy as a small distributed energy source and analyzed dynamic characteristics corresponding to load variation.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.19-21
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• 2006

In contrast with DC source, Fell cell has non linear characteristics that has lange voltage fluctuation due to load variation, and slow dynamic characteristics. when the loads are increase, the ripples of input and output voltage, also power densities, of inductor, capacitor, and switching devices, are bulky. This paper presents Interleaved boost converter using Fuel cell stacks, proposed converter has merits to promote power densities without increasing loss. Because each converter has same switching frequency and constant phase difference. In this paper, Interleaved boost converter was design for 1[kW], it's validity was proved by simulation and experiments.

• Journal of Electrical Engineering and Technology
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• v.5 no.4
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• pp.580-591
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• 2010

This paper deals with an observer design for a P-Cell Chopper. The goal is to reduce drastically the number of sensors in such system by using an observer in order to estimate all the capacitor voltages. Furthermore, considering an instantaneous model of a p-cell chopper, an interconnected observer is designed in order to estimate the capacitor voltages and some parameters of the model. This is realized by using only the load current measurement. Simulation results are given in order to illustrate the performance of such observer. To show the validity of our approach, experimental based a DSP results are presented.