• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.4
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• pp.359-366
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• 2013

This study aims to investigate the characteristics of the flow-induced vibrations of two circular cylinders. The characteristics of the flow-induced vibrations are examined for various flow velocities and spaces between the two cylinders when they are arranged in tandem, staggered, and side-by-side positions. The results are as follows: (i) Seven flow-induced vibration patterns are observed when the two circular cylinders are placed in either tandem, staggered, or side-by-side positions. (ii) The two cylinders induce a vibration because they affect each other. (iii) The easiest way to induce a vibration of the two cylinders is by placing them in the side-by-side position among the three arrangements (tandem, staggered, and side-by-side). (iv) The change in the maximum flow-induced vibration of the two cylinders depends strongly on the fluctuating lift forces of each of them.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.1
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• pp.55-60
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• 2012

This experimental study investigated the characteristics of flow-induced vibration of two elastically supported circular cylinders in a side-by-side arrangement. In particular, the characteristics of the flow-induced vibration of the two cylinders are investigated by changing the flow speed at each spacing ratio L/D (L is the space between two cylinders and D is the diameter of the cylinder). To clarify the mechanism generating the flow-induced vibration of the cylinders, the flow patterns around the two vibrating cylinders are also investigated using a flow visualization test that reproduces the flow-induced vibration of the cylinders with a forced vibration apparatus. As a result, it is clarified that the flow-induced vibration characteristics of the two cylinders arranged side-by-side switch among four patterns as the flow between the two cylinders is switched. Among the three arrangements considered (tandem, staggered, and side-by-side), the arrangement that generates flow-induced vibration of the two cylinders most easily is the side-by-side arrangement.

• The KIPS Transactions:PartA
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• v.11A no.1
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• pp.1-10
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• 2004

A cellular array parallel multiplier with parallel-inputs and parallel-outputs for performing the multiplication of two polynomials in the finite fields GF$(2^m)$ is presented in this paper. The presented cellular way parallel multiplier consists of three operation parts: the multiplicative operation part (MULOP), the irreducible polynomial operation part (IPOP), and the modular operation part (MODOP). The MULOP and the MODOP are composed if the basic cells which are designed with AND Bates and XOR Bates. The IPOP is constructed by XOR gates and D flip-flops. This multiplier is simulated by clock period l${\mu}\textrm{s}$ using PSpice. The proposed multiplier is designed by 24 AND gates, 32 XOR gates and 4 D flip-flops when degree m is 4. In case of using AOP irreducible polynomial, this multiplier requires 24 AND gates and XOR fates respectively. and not use D flip-flop. The operating time of MULOP in the presented multiplier requires one unit time(clock time), and the operating time of MODOP using IPOP requires m unit times(clock times). Therefore total operating time is m+1 unit times(clock times). The cellular array parallel multiplier is simple and regular for the wire routing and have the properties of concurrency and modularity. Also, it is expansible for the multiplication of two polynomials in the finite fields with very large m.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.3
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• pp.659-666
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• 2015

In this paper, we propose a novel reconstruction method of spatially filtered 3D images in integral imaging based on parallel lens array. The parallel lens array is composed of two lens arrays, which are positioned side by side through longitudinal direction. Conventional spatial filtering method by using convolution property between periodic functions has drawback that is the limitation of the position of target object. this caused the result that the target object should be located on the low depth resolution region. The available spatial filtering region of the spatial filtering method is depending on the focal length and the number of elemental lens in the integral imaging pickup system. In this regard, we propose the parallel lens array system to enhance the available spatial filtering region and depth resolution. The experiment result indicate that the proposed method outperforms the conventional method.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.5
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• pp.87-94
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• 2002

In this paper an asynchronous away multiplier with a parallel array structure is introduced. This parallel array structure is used to make the computation time faster with a lower Power consumption. Asymmetric parallel away structure is used to minimize the average computation time in an asynchronous multiplier. Simulation shows that this structure reduces the time needed for computation by 55% as compared to conventional booth encoding array structures and that the multiplier with the proposed away structure shows a reduction of 40% in the computational time with a relatively lower power consumption.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.827-833
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• 2002

In this paper, a microstrip array antenna for LMDS(Local Multipoint Distribution Service) receiver with corporate feeding network using Chebyshev polynomials is proposed to get the high gain and low side lobe level. The Chebyshev array method is proposed to design the corporate feeding network. LMDS uses 24~27 GHz microwave frequency band to send and receive broadband signals. Measured antenna shows 23.4 dBi gain, 24.96 GHz center frequency, -29.15 dB return loss and 1.2 GHz bandwidth.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.06a
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• pp.16-19
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• 2001

일반적인 응용 프로그램에서 루프는 대부분의 수행시간을 차지하기 때문에 병렬성 추출의 핵심 부분이라 할 수 있다. 병렬성이 많은 구조는 루프 구조이며, 루프를 병렬로 처리하기 위해 각 반복간에 존재하는 데이터의 종속은 프로세서간의 동기화가 필요하다. 본 논문에서는 다중첨자를 갖는 1차원 배열의 루프의 병렬화를 위해 다수 개의 동일한 종속값을 이용하여 종속함수를 생성하고 이를 이용하여 종속관계가 성립하지 않는 비종속 구간(Non-dependence part)을 구한다. 그리고 동일한 값을 가지는 복수개의 종속값 간의 동기화는 외부루프 분할 기법을 이용하여 적은 횟수의 청자가 외부에 위치하도록 하여 간소화한 후 단일 첨자를 갖는 루프에 동기화를 수행하는 기법을 제시한다.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.48-49
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• 2017

태양광 발전 시스템 구현에 있어 가장 큰 문제점 중 하나는 불균일한 태양빛 조건에서의 전체 시스템 발전량 감소이다. 이를 해결하기 위해 module-integrated converter (MIC), dc optimizer, differential power processing (DPP) 등 다양한 컨버터가 연구되고 있다. 그 중에서도 DPP 컨버터는 낮은 전력변환 손실로 높은 시스템 효율을 얻을 수 있어 최근 많은 주목을 받고 있다. 보통 그리드 연결형 태양광발전 시스템에 적용되는 직렬 DPP의 경우, 이미 많은 연구가 진행되고 있지만, 병렬 DPP의 경우 아직 많은 연구가 필요한 상황이다. 본 논문에서는 front-end 컨버터의 존재 유무에 따른 두 가지 병렬 DPP 컨버터 배열을 비교 분석 하였다. Front-end 컨버터가 적용된 병렬 DPP 컨버터 배열의 경우, dc 전압과 태양전지의 전압 차이를 최소화해 전력 변환 손실을 감소시킬 수 있지만, front-end 컨버터에서 추가적인 전력 변환 손실이 발생한다. Front-end 컨버터가 없는 경우, dc 전압과 태양전지의 전압차이가 커 DPP 컨버터에서 발생하는 전력 변환 손실이 커진다. 따라서 주어진 조건 아래 효율적인 병렬 DPP 컨버터 디자인을 위한 가이드라인을 본 논문에서 제시하고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4136-4141
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• 2013

One of the most significant requisite that should be considered for effective rapping of the electrostatic precipitator using electromagnetic vibration exciter is vibration acceleration and resonance frequency of collecting plates. This vibration acceleration shows its peak points when natural frequencies of the system are corresponded with excitation frequency from the power source, and effective rapping performance can be expected. In this research, extend view of single electrostatic precipitator using one electromagnetic vibration exciter, the system was remodeled by arrangement of the exciters in view of multiple modules of the electrostatic precipitator in fields. And vibration acceleration measurement experiment is performed and measured values are compared with these remodeled systems. By this experimental comparison in series and parallel arrangement, effectiveness of arrangement methods for the electromagnetic vibration exciter, expected rapping performance, and power consumption are verified.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.1
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• pp.54-65
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• 2000

We propose a parallel acquisition scheme using antenna arrays for initial acquisition of direct-sequence spread-spectrum (DS-SS) signals. The proposed parallel scheme can lower substantially the range of detectable signal-to-noise ratio (SNR) as compared to the conventional parallel scheme with a single antenna. The proposed scheme uses the sum of the independent decision samples from antenna arrays corresponding to an identical subsequence of the pseudonoise (PN) code as a decision variable. We derive the probabilities of detection, missing, and false alarm under an additive white Gaussian noise (AWGN) channel and a flat Rayleigh fading channel. Using these, we get the mean acquisition time of the proposed scheme. From numerical results, we see that the acquisition performance becomes improved continually as the number of antennas increases.