• Journal of applied mathematics & informatics
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• 제26권5_6호
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• pp.945-959
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• 2008

n-ary $H_v$-structures is a generalisation of both n-ary structures and $H_v$-structures. A wide class of n-ary $P-H_v$-groups is the n-ary $P-H_v$-groups that is concidered in this paper. In this paper the notion of a normal subgroup of an n-ary $P-H_v$-groups is introduced and the isomorphism theorems for n-ary $P-H_v$-groups are stated and proved. Also some examples and related properties are investigated.

• 대한수학회보
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• 제41권4호
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• pp.731-737
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• 2004

We investigate change of the tensor ${U^{v}}_{\omega\mu}$ induced by the conformal change in 7-dimensional g-unified field theory. These topics will be studied for the second class with the first category in 7-dimensional case.

• Journal of applied mathematics & informatics
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• 제28권5_6호
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• pp.1535-1544
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• 2010

Sufficient optimality conditions for a class of generalized non-differentiable fractional optimization programming problems are established. Moreover, we prove the weak and strong duality theorems under (V, $\rho$)-invexity assumption.

• 한국전자통신학회논문지
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• 제4권4호
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• pp.265-269
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• 2009

다자간 회의용키 협의는 제3의 신뢰기관 없이 다수의 구성원 참여에 의해 회의용 세션키를 생성함으로 말한다. 이 논문에서는 SBIBD(symmetric balanced incomplete block design)를 이용한 효율적인 회의용 키협의 프로토콜을 제안한다. 제안된 방식은 회의 참여자간 교환하는 메시지의 양과 메시지 교환 횟수를 최소화하고 각 참여자가 균등한 메시지 오버헤드를 갖도록 한다. 제안된 프로토콜에서는 v명의 참여자가 있고 각 참여자 i가 생성한 랜덤 넘버가$R_i$라고 할 때 Diffe-Helman의 세션키 생성법을 변형한${\prod}_{i=0}^{v-1}R_i$ 형태의 키를 생성하게 된다. 이 때 메시지 교환횟수는 3회, 메시지 오버헤드는 $O(v{\sqrt{v}})$이 된다. 또한 이 프로토콜은 이산대수문제에 근거하여 안전성을 보장한다.

• 전기저널
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• 6호통권90호
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• pp.2-4
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• 1984

• Kyungpook Mathematical Journal
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• 제14권1호
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• pp.45-53
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• 1974

• 조명전기설비학회논문지
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• 제24권1호
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• pp.167-174
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• 2010

본 연구에서는 22.9[kV] 애자의 표면오염에 의한 자외선 영상과 거동을 통해 자외선 이미지 형태 판단법을 정의하였다. 코로나 방전에 의해 나타나는 자외선 영상은 아메바, 젤리피쉬, 썬플라워 형태 등 3가지로 나누어지며, 세부적으로는 8개의 진행 메커니즘으로 구분하였다. 전력설비가 설치된 현장에서는 즉각적으로 이 판단 방법으로 전력 설비의 열화된 부분을 찾을 수 있다. 이는 신뢰성 있는 데이터를 통해 전력설비의 열화를 판단하는 기준에 활용이 가능하다. 향후 현장진단에 적합한 기술로서의 연구가 활용될 것이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
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• pp.3114-3116
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• 2005

The AC-DC converter, which has three-phase AC power as input and isolated DC power as output is used for the regulated DC power supply of the telecommunication power processing system for several kilowatt class applications. The conventional DC power supply for the telecommunication power system comprises a PWM rectifier with sine-wave shaping input current unity power factor and a DC/DC converter connected to the PWM converter, which obtains DC 48[V]. Since power passes through these two power stage converters, the conversion power loss is difficult to provide high efficiency. To resolve these problems, this paper presents a new PWM rectified as a 1-stage power conversion method. It simulation and experimental results as proved from a practical point of view that 92.1[%] of conversion efficiency and input current which can meet harmonics regulation of the Class-A in IEC61000-3-3 are achieved.

• Earthquakes and Structures
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• 제9권5호
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• pp.983-997
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• 2015

This research evaluates the soil conditions for seismic stations situated in Romania using the horizontal-to-vertical spectral ratio (HVSR). The strong ground motion database assembled for this study consists of 179 analogue and digital strong ground motion recordings from four intermediate-depth Vrancea seismic events with $M_w{\geq}6.0$. In the first step of the analysis, the influence of the earthquake magnitude and source-to-site distance on the H/V curves is evaluated. Significant influences from both the earthquake magnitude and hypocentral distance are found especially for soil class A sites. Next, a site classification method proposed in the literature is applied for each seismic station and the soil classes are compared with those obtained from borehole data and from the topographic slope method. In addition, the success and error rates of this method are computed and compared with other studies from the literature. A more in-depth analysis of the H/V results is performed using data from seismic stations in Bucharest and a comparison of the free-field and borehole H/V curves is done for three seismic stations. The results show large differences between the free-field and the borehole curves. As a conclusion, the results from this study represent an intermediary step in the evaluation of the soil conditions for seismic stations in Romania and the need to perform more detailed soil classification analysis is highly emphasized.

• Transactions on Electrical and Electronic Materials
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• 제2권4호
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• pp.1-6
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• 2001

In this paper, a 1.5 V high-gain high-frequency CMOS complementary operational amplifier is presented. The input stage of op-amp is designed for supporting the constant transconductance on the Input stage by consisting of the parallel-connected rail-to-rail complementary differential pairs. And consisting of the class-AB rail-to-rail output stage using the concept of elementary shunt stage and the grounded-gate cascode compensation technique for improving the low PSRR which was a disadvantage in the general CMOS complementary input stage, the load dependence of open loop gain and the stability of op- amp on the output load are improved, and the high-gain high-frequency operation can be achieved. The designed op-amp operates perfectly on the complementary mode with the 180° phase conversion for a 1.5 V supply voltage, and shows the DC open loop gain of 84 dB, the phase margin of 65°, and the unity gain frequency of 20 MHz. In addition, the amplifier shows the 0.1 % settling time of .179 ㎲ for the positive step and 0.154 ㎲ for the negative step on the 100 mV small-signal step, respectively, and shows the total power dissipation of 8.93 mW.