• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.351-354
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• 1998

In this paper, electrical characteristics of an n-channel Si MOSFET with L$_{s}$=0.6.mu.m under optical illumination are charaterized on wafer. Energetic photons with .gamma.=830nm, hv=1.494eV, P$_{opt}$=300mW are injected near the drain junction, the most photoresponsive region in the device, via optical fiber. We observed significantly increased drain current and transconductance, which is considered to be useful for the implementation of OEICs on silicon substrate, under optical control with P$_{opt}$=300mW. Optical power-dependent physical mechanisms responsible for the variation of electrical characteristics under optical input are also reported.d.d.d.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.345-350
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• 2000

The objective of this study makes investigation into the effect on the properties of underwater antiwashout concrete. which is followed by mixing time and mixing quantity. There is an tendency that (the compressive strength of underwater antiwashout concrete made and cured in fresh water or sea water) is increase when dry mixing time, mixing quantity, total mixing time is increase as unit weight grows. The difference of compressive strength (in case of no dry mixing time and 60 second) is averagely 46.8kgf/㎠ in the fresh water and 35.6kgf/㎠ in sea water. it's considered that dry mixing is dispersed by underwater antiwashout admixture.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2006.05a
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• pp.331-335
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• 2006

인터넷의 발달과 사용자 증가로 인해 IETF는 다양한 네트워크와 프로토콜 상에서 안전하고 신뢰성 있는 사용자 인증을 위해 AAA를 제안하였다. 그러나 AAA의 최신 버전인 Diameter 표준의 인증 방식은 상호인증과 부인방지를 제공하지 않는다. 이러한 Diameter의 인증을 보완하기 위해 공개키를 이용한 AAA 인증 방식이 제안되었으나, 통신과 연산의 오버헤드로 인해 이동 노드에 적용이 어렵다. 이러한 단점을 극복한 ID 기반 AAA 인증 방식이 제안 되었으나 공모공격과 위장공격으로부터의 취약점을 가진다. 이 논문에서는 공모공격과 위장공격에 안전하고, 계산적 전력적 능력이 부족한 이동 노드의 연산량을 감소시키는 새로운 ID기반 AAA인증 방식을 제안한다. 제안한 방식의 검증을 위해 기존 방식을 비교 평가하여 암호학적인 안전성과 연산량의 효율성을 검증한다. 제안 방식은 이동 노드의 인증시 2개의 난수를 생성하여 안전성을 제공하며, Mobile 노드의 지수연산을 줄임으로 계산 전력적 측면에서 효율적이고 서버의 성능에 따라 인증 수행 시간을 감소 시켜 끊김 없는 서비스를 제공할 수 있는 장점을 갖는다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.244-247
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• 2002

In order to evaluate the water ingress to URD power cables with the jacketing materials and the cable structures, water vapor transmission (WVT) tests were carried out by the ASTM and the TEPCO's specification. All polyolefin compounds showed the superior water suppression to conventional PVC. Especially, linear polyethylenes have very low WVT. In case of cable structures, Allaminate cables showed the significant water suppression due to the watertight structure. Accordingly, it can be concluded that jacketing material and cable structure play an important role in the water suppression of URD power cables.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.8
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• pp.687-694
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• 2002

In order to replace the jacket material for URD power cables, the 6 kinds of polyethylene compounds were manufactured and evaluated. The characteristics of the compounds were investigated by water vapor transmission (WVT) test, thermal and mechanical test. In WVT test, all the polyethylene compounds showed the superior water resistance to conventional PVC. The molecular structure and density of polyethylene play an important role in WVT. Also, the polyethylene compounds showed the suitable characteristics in thermal and mechanical test. Especially, the linear polyethylene compounds showed the superior characteristics to LDPE ones. Due to the fillers in compounds, the abrasion resistance was decreased and the cut-through resistance was increased. From this study, it can be considered that the polyethylene compounds may be suitable to jacket material for URD power cables.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.406-409
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• 2002

The primary insulation system used in an oil-filled transformer is Kraft paper, wood, porcelain and, of course, oil. Modern transformers use paper that is chemically treated to improve its tensile strength properties and resistance to aging caused by immersion in oil. These insulation papers are mainly aged to thermal stress. Over the course of the insulation paper and oil's life it is exposed to high temperatures, oxygen and water. Its interaction with the steel of the tank and core plus the copper and aluminium of the windings will eventually cause the chemical properties of the oil to decay. High temperature have an effect on mechanical strength of cellulous paper using the layer insulation. We made two aging cell in which thermal aging tests of insulation papers and mineral oil are conducted. It is measured dielectric strength, number of acid, moisture, etc. of insulation paper and oil aged in the aging cells.

• Journal of Environmental Science International
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• v.20 no.4
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• pp.519-525
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• 2011

A three-dimensional ecological model(EMT-3D) was applied to DAS1 in Tokyo Bay. The simulated results of DAS1 were in good agreement with the observed values. The result of sensitivity analysis showed that photolysis coefficient and extinction coefficient were important factor for dissolved DAS1, and photolysis coefficient, extinction and POC partition coefficient for PAHs in particulate organic matter. Mass balance of DAS1 in Tokyo Bay was calculated by using the simulated results of EMT-3D.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.967-970
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• 2003

A new adder-and-accumulator (A$^2$C) adapted to pipelined Δ$\Sigma$ modulators is proposed in this paper. With the viewpoint of area consumption, registers are removed in the existing pipelined Δ$\Sigma$ modulator, and then adder and accumulator are merged. In order to optimize area consumption, speed and power consumption, dynamic carry look-ahead adder (CLA) is adopted in $A^2$C. Moreover, a guideline for the transistor sizing in CLA with regard to the minimization of the energy-delay-area product (EDAP) is proposed[1]. The proposed $A^2$C has been verified by HSPICE simulations.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.815-818
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• 2003

New sensing and writing schemes for a magneto-resistive random access memory (MRAM) with a twin cell structure are proposed. In order to enhance the cell reliability, a scheme of the low voltage precharge is employed to keep the magneto resistance (MR) ratio constant. Moreover, a common gate amplifier is utilized to provide sufficient voltage signal to the bit line sense amplifiers under the small MR ratio structures. To enhance the writing reliability, a current mode technique with tri-state current drivers is adopted. During write operations, the bit and /bit lines are connected. And 'HIGH' or 'LOW' data is determined in terms of the current direction flowing through the MTJ cell. With the viewpoint of the improved reliability of the cell behavior and sensing margin, HSPICE simulations proved the validity of the proposed schemes.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.863-866
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• 2003

Recently, there has been growing interests in the magneto-resistive random access memory (MRAM) because of its great potential as a future nonvolatile memory. In this paper, a CMOS macro-model for MRAM cell based on a twin cell structure is proposed. The READ and WRITE operations of the MTJ cell can be emulated by adopting data latch and switch blocks. The behavior of the circuit is confirmed by HSPICE simulations in a 0.35-${\mu}{\textrm}{m}$ CMOS process. We expect the macro model can be utilized to develope the core architecture and the peripheral circuitry. It can also be used for the characterization and the direction of the real MTJ cells.