• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1546-1548
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• 1998

Dual mode ring resonators(DMRR) have been fabricated using laser ablated $YBa_2Cu_3O_{7-x}$ superconducting thin films. The transition temperature of YBCO thin films were 85 - 88 K and the film thicknesses were about 5,000 $\AA$. Dual mode ring resonators were patterned by standard photolithography process and wet-etching. Then two-layer metal thin films (Ti/Ag) have been deposited for the ground plane on the back side of substrate by e-beam and thermal evaporation. The input/output feedline angles of each resonator were $60^{\circ}$, $100^{\circ}$, $180^{\circ}$. A network analyzer was used for testing the performance of the resonators in the frequency range of 6-13 GHz at 77 K.

• 한국전자파학회논문지
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• 제26권3호
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• pp.300-304
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• 2015

본 논문에서는 무선전력전송용 전 방향 빔 조향 직교 공진기를 제안하였다. 전 방향 빔 조향 직교 공진기는 2개의 루프를 수직으로 교차하여 이들의 연결 관계를 스위치로 제어하는 방식이다. 스위치의 연결 방식에 따라 루프에 흐르는 전류의 방향이 결정되고, 그에 따라 빔 조향 방향이 결정된다. 수직으로 교차한 공진기의 전류와 그에 따라 형성되는 자기장의 벡터 합의 원리를 이용하여 대각선 방향으로의 빔 조향을 실현하였다. 4개의 스위치 mode를 통해서 총 8개 방향으로 빔 조향이 가능하다. 적합한 스위치 mode를 사용하여 전 방향에 대한 전송 효율을 구하면 시뮬레이션과 측정 결과가 각각 56.3~60.0 %(편차 3.7 %), 41.2~48.7 %(편차 7.5 %)으로 비교적 전 방향에 대해 균일한 전송 효율을 얻을 수 있다.

• Journal of Mechanical Science and Technology
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• 제16권1호
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• pp.32-38
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• 2002

The purpose of this study is to analyze the collapse characteristics of widely used spot welded section members (hat and double hat section, nembers of vehicles) which possess the greatest energy absorbing capacity In an axial impact collapse. This study also suggests how the collapse load and deformation mode are obtained under impact. In the program system presented in this study, an explicit finite element code, LS-DY7A3D, is adopted for simulating complicated collapse behavior of the hat and double hat shaped section members with respect to section dimensions and spot weld pitches. Comparing the results with experiments, the simulation has been verified under a velocity of 7.19 m/sec (impact energy of 1034J)

• Journal of Electrical Engineering and Technology
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• 제7권2호
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• pp.163-170
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• 2012

This paper presents a DFT (Discrete Fourier Transform) based estimation algorithm for the parameters of a low-frequency oscillating signal. The proposed method estimates the parameters, i.e., the frequency, the damping factor, the mode amplitude, and the phase, by fitting a discrete Fourier spectrum with an exponentially damped cosine function. Parameter estimation algorithms that consider the spectrum leakage of the discrete Fourier spectrum are introduced. The multi-domain mode test functions are tested in order to verify the accuracy and efficiency of the proposed method. The results show that the proposed algorithms are highly applicable to the practical computation of low-frequency parameter estimations based on DFTs.

• The Journal of the Acoustical Society of Korea
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• 제16권3E호
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• pp.7-13
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• 1997

This paper addresses traffic prediction issues on MPEG. A new adaptive traffic prediction scheme is proposed using MPEG picture characteristic that picture traffic depends on the coding mode of that picture, that is, I, P, and B mode. Our prediction scheme, which is based n picture decomposition (PD) and the cross-correlation of the different types of pictures, has better performance in predicting bursty MPEG traffic than that of the first-order autoregressive (AR) prediction scheme. Our simulation results show that the performance is further improved about 15% by utilizing the cross-correlations between pictures.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1507_1508
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• 2009

This study proposes a composite right/left-handed transmission line (CRLH-TL) that permits switching between the right-handed (RH) and left-handed (LH) modes using single crystalline silicon (SCS) RF MEMS switches. It is possible to change modes from the RH to LH mode, or vice versa, by controlling the admittance of capacitors and the impedance of inductors using switch operations. The proposed switchable CRLH-TL consists of SCS RF MEMS switches, metal-insulator-metal (MIM) capacitors and shunt inductors. At 8 GHz, the fabricated device shows a phase response of $87^{\circ}$ with an insertion loss of 2.7 dB in the LH mode, and a phase response of $-77^{\circ}$ with an insertion loss of 0.56 dB in the RH mode.

• 대한기계학회논문집A
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• 제35권7호
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• pp.767-772
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• 2011

궤적생성은 로봇보행의 안정성, 연속성 그리고 보행특성을 결정하는 가장 중요한 일이다. 보통 궤적생성법으로 LIPM을 많이 쓰지만 그것은 그것의 선형화 기법 때문에 수직방향으로의 동작생성을 할 수 없다는 단점이 있다. 이 논문에서는 ELIPM이라는 새로운 궤적생성법을 제안한다. 이 궤적생성법은 전진방향의 동작은 물론이고 수직방향의 동작을 간단하게 생성할 수 있다.

• 한국정밀공학회지
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• 제30권7호
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• pp.754-761
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• 2013

Thermal displacement is an important issue in machine tool systems. During the last several decades, thermal error compensation technology has significantly reduced thermal distortion error; this success has been attributed to the development of a precise, robust thermal error model. A major advantage of using the thermal error model is instant compensation for the control variables during the modeling process. However, successful application of thermal error modeling requires correct determination of the temperature sensor placement. In this paper, a procedure for predicting thermal-mode-based thermal error is introduced. Based on this thermal analysis, temperature sensors were positioned for multiple heat-source models. The performance of the sensors based on thermal-mode error analysis, was compared with conventional methods through simulation and experiments, for the case of a slide table in a transient state. Our results show that for predicting thermal error the proposed thermal model is more accurate than the conventional model.

• 정보저장시스템학회논문집
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• 제7권2호
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• pp.53-59
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• 2011

We have developed a compact and high-power mode-locked fiber laser for multilayered optical memory. Fiber lasers have the potential to be compact and stable light sources that can replace bulk solid-state lasers. To generate high-power pulses, we used stretched-pulse mode locking. The average power and pulse width of the output pulse from the fiber laser that we developed were 109 mW and 2.1 ps, respectively. The dispersion of the output pulse was compensated with an external single-mode fiber of 2.5 m length. The pulse was compressed from 2.1 ps to 93 fs by dispersion compensation. The fiber laser we have developed is possible to use as a light source of multilayered optical memory. We also present a fiber confocal microscope as an alignment-free readout system of multilayered optical memories. The fiber confocal microscope does not require fine pinhole position alignment because the fiber core is used as the point light source and the pinhole, and both of which are always located at the conjugated point. The configuration reduces the required accuracy of pinhole position alignment. With these techniques we can present an all-fiber recording and readout system for multilayered memories.

• Journal of Information Processing Systems
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• 제7권4호
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• pp.679-690
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• 2011

In this paper we consider a local area network (LAN) of dual mode service where one is a token bus and the other is a carrier sense multiple access with a collision detection (CSMA/CD) bus. The objective of the paper is to find the overall cell/packet dropping probability of a dual mode LAN for finite length queue M/G/1(m) traffic. Here, the offered traffic of the LAN is taken to be the equivalent carried traffic of a one-millisecond delay. The concept of a tabular solution for two-dimensional Poisson's traffic of circuit switching is adapted here to find the cell dropping probability of the dual mode packet service. Although the work is done for the traffic of similar bandwidth, it can be extended for the case of a dissimilar bandwidth of a circuit switched network.