• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.6
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• pp.105-112
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• 2003

Diode rectifier which can't be controlled output voltage and phase control converter as AC/DC converter have low power factor and harmonics of lower order in the line current. In this paper, three phase PWM(Pulse Width Modulation) AC/DC boost converter is studied to solve these problems. The characteristics of a proposed converter are to control the phase of current without current sensor as a very simple control algorithm using circuit parameters only and to apply sinusoidal PWM method with fixed switching frequency due to a difficult design of input filter and switching device. We simulate for the proposed algorithm that high power factor is achieved and DC link voltage has fast dynamic response without ripple in rectifying and regenerating operation. As a result of experiment with circuit parameter(inductor, capacitor) decided in simulation, the proposed converter had high power factor and reduction of low order harmonics as against diode rectifier.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.669-676
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• 2012

In this paper, The method to improve the mass production method of the radar sensor is suggested by using the temperature compensation circuit which is composed with the thermister. The mass production became easier by decreasing the adjustment time for the exact oscillation frequency with the temperature compensation circuit that can support the proper gate bias voltage for the FET after the dielectric resonator is removed from the DRO(Dielectric Resonator Oscillator) of the radar sensor. Radar sensor with the proposed method has 15.67MHz oscillator frequency variation in the temperature range of $-20^{\circ}C-+55^{\circ}C$, 0.65dB magnitude variation, -105.47dBc phase noise characteristics at 1MHz which are better or similar temperature characteristics with the DRO whose oscillator frequency variation is 25MHz, magnitude variation is 0.42dB and phase noise is -107.40dBc in the same temperature range.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.5
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• pp.1199-1206
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• 2015

This paper introduces an algorithm for computing similarity between two poses in the motion capture data with different scale of skeleton, different number of joints and different joint names. The proposed algorithm first performs the topological analysis on the skeleton hierarchy for classifying the joints into more meaningful groups. The global joints positions of each joint group then are aggregated into a point cloud. The number of joints and their positions are automatically adjusted in this process. Once we have two point clouds, the algorithm finds an optimal 2D transform matrix that transforms one point cloud to the other as closely as possible. Then, the similarity can be obtained by summing up all distance values between two points clouds after applying the 2D transform matrix. After some experiment, we found that the proposed algorithm is able to compute the similarity between two poses regardless of their scale, joint name and the number of joints.

• Journal of Convergence for Information Technology
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• v.10 no.6
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• pp.14-18
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• 2020

In this paper, when two sets of cross-eye jammer antennas are installed vertically to jam a monopulse radar, the jamming effects according to the jammer's phase difference, amplitude ratio, and radar angle of engagement are analyzed. The phase difference and amplitude ratio of the cross-eye jammer can be adjusted in the jammer, but since the angle of engagement is relatively determined by the radar, it is very important to respond to changes in the angle of engagement. The orthogonally deployed jammer antennas can be considered as a good way to increase the jamming effect while minimizing the hardware configuration, and the jamming effect is analyzed while changing the angle of inclination from 0° to 360°. This jammer greatly improves the jamming effects at the angles of incidence 45°~135° and 225°~315°, compared to a single jammer. And it is expected to be useful in the design of cross-eye jammers for military aircraft and ships.

• Journal of Astronomy and Space Sciences
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• v.14 no.2
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• pp.347-354
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• 1997

We developed a GPS phase data processing S/W system which calculates baseline vectors and distances between two points located in the surface of the Earth. For this development a Double-Difference mothod and L1 carrier phase data from GPS(Global positioning System) were used. This S/W system consists of four main parts: satellite position calculation, Single-Difference equation, Double-Difference equation, and correlation. To verify our S/W, we fixed KAO($N36^{circ}.37,E127^{circ}.37,H77.61m$), one of the International GPS Services for Geodynamics, which is located at Tae-Jon, and we measured baseline vectors and relative distances with data from observations at approximate baseline distances of 2.7, 42.1, 81.1, 146.6km. Then we compared the vectors and distances with the data which we obtained from the GPSurvey S/W system, with the L1/L2 ION-Free method and broadcast ephemeris. From the comparison of the vectors and distances with the data from the GPSurvey S/W system, we found baseline vectors X, Y, Z and baseline distances matched well within the extent of 50cm and 10cm, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4A
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• pp.307-314
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• 2010

In this paper, a receive diversity combining technique is proposed for single-carrier frequency division multiple access (SC-FDMA)-based cooperative relay systems when discrete Fourier transform (DFT) spreading sizes for mobile station (MS) and relay station (RS) are different. The proposed technique is composed of a DFT spreading size adjustment block, a phase rotation compensation block, a channel phase compensation block, and a receive diversity combining block. The proposed technique is robust to multipath channels and can be operated with a relatively small computational complexity because receive diversity combining is performed with scalar operations in the frequency-domain. It is shown by computer simulation that the proposed receive diversity combining techniques achieve a performance gain over the conventional maximal ratio combining (MRC) techniques for SC-FDMA-based cooperative relay systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.522-529
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• 2007

A semidynamic frequency divide-by-1.5 MMIC comprises a tunable polyphase filter, tunable image-rejection mixer, and a static divide-by-2 in the feedback path. Wideband suppression of unwanted tones is achieved by employing a tunable image-rejection mixer and a tunable single-stage polyphase filter. Implemented in GaInP/GaAs HBT technology, the divide-by-1.5 MMIC operates over the input frequency range of 4.5 to 9.2 GHz with better than -20 dBc suppressions of $1/3{\times}f_{in}\;and\;f_{in}$ tones, while dissipating 29 mA from 4.1 V supply.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.25 no.1
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• pp.24-28
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• 1989

This paper describes a fundamental method to suppress vibration of a structure under excitation by attaching a impact absorber. The influence of the shape of impact absorber, such as weight of add mass, impact clearance, contacting area and the exciting frequency on suppressing vibrations of the structure is investigated. The effectiveness of the proposed vibration absorber is demonstrated experimentally.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.11
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• pp.1545-1550
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• 2021

We propose an optimal variable step size adjustment method for the simplified subband affine projection algorithm (Simplified SAP; SSAP) in a subband structure based on a polyphase decomposition technique. The proposed method provides an optimal step size derived to minimize the mean square deviation(MSD) at the time of updating the coefficients of the subband adaptive filter. Application of the proposed optimal step size in the SSAP algorithm using colored input signals ensures fast convergence speed and small steady-state error. The results of computer simulations performed using AR(2) signals and real voices as input signals prove the validity of the proposed optimal step size for the SSAP algorithm. Also, the simulation results show that the proposed algorithm has a faster convergence rate and good steady-state error compared to the existing other adaptive algorithms.

• Asia Marketing Journal
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• v.9 no.3
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• pp.233-255
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• 2007

본 사례는 외환위기 및 대우 그룹 해체로 인해 존폐의 위기에 처했던 대우증권이 선도업체 위상을 탈환하기까지의 재건 과정에서 실행했던 마케팅 전략 및 영업활동을 분석하고 있다. 이를 통해 경영위기를 효과적으로 극복하고 새롭게 도약하기 위해 활용 가능한 마케팅 및 영업 전략의 일례를 소개하고자 한다. 끝으로 대우증권의 향후 마케팅 과제와 관련된 토의 주제가 제시된다. 국내 증권업계 선두주자였던 대우증권은 1999년 '대우 사태'로 인해 한때 업계 5위까지 추락하고 1조 2,000억원의 적자를 기록하였으며 신용등급은 투자부적격 단계인 CCC+까지 하락하는 등 위기를 맞이하게 되었다. 대우증권이 회생과 재도약을 위해 채택한 마케팅 전략은 '선택과 집중'이었다. 즉, 최대 수익원이자 경쟁력이 있는 사업 분야인 위탁매매(brokerage)에 역량을 우선 집중하여 안정적으로 수익 기반을 다진 뒤 이를 바탕으로 IB(Investment Bank)와 자산 관리(Wealth Management) 등 여타 분야에서의 역량도 점진적으로 강화하는 전략이다. 전략의 실행 방향은 높은 효율성 확보 및 자원의 확충을 통해 시장 지배력과 수익성을 창출하는 것이었다. 전략적 공감대, 오프라인 영업 강화, 현장 및 고객 중시를 위한 기업 자원의 확충 배치를 바탕으로 영업 프로세스, 영업 인프라, 영업 관리, 고객 서비스, 영업 문화의 혁신을 실행한 결과, 대우증권은 증권명가의 옛 명성과 위치를 성공적으로 탈환하게 되었다. 대우증권은 2004년 위탁매매 영업 부문에서 1위 위상을 되찾은 이래 전 사업 분야에서 성장을 지속하였다. 2006년 증권업종 시가총액 1위를 회복하는 등 각종 경영지표는 큰 폭으로 개선되었고, 신용등급은 AA-로 상향 조정되었다. 나아가 자본시장통합법 시대에 걸맞는 선도 글로벌 투자은행으로서 진화한다는 계획을 추진하고 있다.