• 한국정보전자통신기술학회논문지
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• 제3권4호
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• pp.76-82
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• 2010

기지국 섹터 배열안테나의 하향 빔틸트 각도를 조절하기 위해 전압제어 이상기를 사용하였다. 틸트 각도에 따른 각 안테나의 위상각을 도출하였으며 이때 생성되는 패턴의 수직과 수평 방향 성능을 분석 평가하였다. 이러한 분석을 통해 이동통신 기지국안테나의 셀커버리지 확보와 통화율 증대, 간섭 저감을 이룰 수 있어 최적의 기지국안테나 설계에 적용 가능할 것이다.

• 한국음향학회지
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• 제43권1호
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• pp.29-38
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• 2024

정합장처리(Matched Field Processing, MFP)는 음파전달 예측을 기반으로 음원의 거리와 심도를 추정하는 기법이다. 그러나 주파수가 높아지면 음파전달 예측의 부정확성이 증가하여 음원위치 추정이 어렵다. 최근에 제안된 차주파수 정합장처리(Frequency-difference Matched Field Processing, FD-MFP)는 고주파 신호의 자기상관으로부터 추출한 차주파수 곱을 적용함으로써 음속의 오정합 등이 있어도 강인하다고 알려졌다. 본 논문에서는 수평선배열센서에서 차주파수 정합장처리의 성능을 알아보기 위하여, 동해의 환경에서 시뮬레이션을 수행하였다. 장거리 탐지가 가능한 해저면반사(Bottom Bounce, BB)와 수렴구역(Convergence Zone, CZ)이 발생하는 영역에서 위치추정 결과를 분석하였다. 수평선배열센서의 차주파수 정합장처리의 위치추정 정확도는 회절음장과 음속의 오정합에 의해 기존의 정합장처리에 비해 유사하거나 낮아졌다. 시뮬레이션으로부터 차주파수 정합장처리가 기존의 정합장처리보다 오정합에 강인하다는 명확한 결과는 볼 수 없었다.

• 한국정보통신학회논문지
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• 제14권7호
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• pp.1581-1588
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• 2010

대부분의 디지털 촬영 장치는 비용 및 속도 상의 이점을 위해 Color Filter Array(CFA)를 포함하고 있는 단일 이미지 센서를 사용한다. 따라서 완전한 컬러 영상으로 복원하기 위하여 다양한 컬러 보간 방법이 개발되고 있다. 본 논문은 이러한 컬러 보간 방법 중, 방향성 필터를 이용하여 수직, 수평, 대각선 방향의 에지를 고려한 컬러 보간 방법에 관한 것이다. 하드웨어 구현을 위해 하드웨어 자원의 효율성을 고려하였다. Kodak 테스트 영상 24장으로 실험하여 기존 방법과 비교함으로써 제안한 방법의 성능을 확인하였다. Verilog HDL로 구현하였으며, Virtex4 FPGA 보드와 CMOS 이미지 센서를 이용하여 검증하였다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.659-663
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• 2009

In this paper, we propose a rectification method that can convert ray space data obtained by controlled camera array to ideal data. Here, Ideal data is obtained by getting longitudinal and transversal epipolar line between cameras vertical and horizontal. However it is actually difficult to arrange cameras strictly because we arrange cameras by hand. As conventional method, we have use camera-calibration method. But if we use this method there are some errors on the output image. When we generate arbitrary viewpoint images this error is critical problem. We focus attention on ideal trajectory of characteristic point. And to minimize the error directly we parallelize the real one. And we showed usefulness of proposed technique. Then using the proposed technique, we were successful reducing the error to less than 0.5 pixels.

• 정보통신설비학회논문지
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• 제10권1호
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• pp.7-13
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• 2011

Matrix multiplication is a fundamental operation of linear algebra and arises in many areas of science and engineering. This paper introduces an efficient parallel matrix multiplication scheme on N ${\times}$ N mesh-connected SIMD array processor, called multiple hierarchical SIMD architecture (HMSA). The architectural characteristic of HMSA is the hierarchically structured control units which consist of a global control unit, N local control units configured diagonally, and $N^2$ processing elements (PEs) arranged in an N ${\times}$ N array. PEs are communicating through local buses connecting four adjacent neighbor PEs in mesh-torus networks and global buses running across the rows and columns called horizontal buses and vertical buses, respectively. This architecture enables HMSA to have the features of diagonally indexed concurrent broadcast and the accessibility to either rows (row control mode) or columns (column control mode) of 2D array PEs alternately. An algorithmic mapping method is used for performance evaluation by mapping matrix multiplication on the proposed architecture. The asymptotic time complexities of them are evaluated and the result shows that paralle matrix multiplication on HMSA can provide significant performance improvement.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.412-417
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• 2005

To ensure the safety of the tunnelling without the loss of economy, the tunnel seismic profiling(TSP) method for the prediction ahead of tunnel face, begins to be used routinely in these days. TSP method does not interfere the tunnelling works while the horizontal drilling does, and its prediction length is longer than that of the drilling. Yet the most frequently adopted technique of TSP in Korea is the multi-shot and 2 receiver array using in-hole receivers, even though this array requires as many as 26 drill-holes for receiver installation and ballasting, which results in 3-6 hours of suspension in excavation work. In this paper, multi-receiver and lesser shot array using side-wall attached 3 component geophones is to be described to prove the efficiency in terms of the survey time as well as the reliability of the method by comparison of the predicted weak points and the face mapping results. The predictions mostly agreed with the real fractures or joint developed zones which have been confirmed during the excavation. It also has been found that TSP method can be effectively applied to perform draining ground water ahead of tunnel face by imaging the geologic discontinuities.

• 한국수소및신에너지학회논문집
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• 제24권1호
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• pp.84-90
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• 2013

The hydrogen or oxygen gas producted by electrolysis become many bubbles in the electrolyte, but exact data on the behavior of these bubbles in the separator of an electrolysis stack didn't become known. In this study, the flow visualization experiment on the behavior of bubbles in the flow pattern of the array type separator is performed by using of a visible alkaline electrolysis stack and a stereoscopic microscope. As the results, a fine size bubbles adhered to the surface of the flow pattern grow to large sized bubbles until each bubble's buoyance is lager than the sum of external force and weight. And then the large bubbles flow into the upper area of the separator. Bubbles adhered to the surface of the vertical flow pattern grow quickly than them adhered to the surface of the horizontal flow pattern. Also, he electrolysis efficiency is declined because many multi-size bubbles occupied the wide volume in the flow pattern.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2055-2060
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• 2007

Microfin arrays with fin heights of 100 ${\mu}$m and 200 ${\mu}$m and six different spacings from 30 ${\mu}m$to 360 ${\mu}m$ are fabricated using the DRIE process. Natural convective heat transfer around the microfin arrays on both vertical and horizontal surfaces is experimentally examined. It turns out that the orientation effect of microfin arrays is negligible compared with macrofin arrays. The obtained heat transfer coefficients are compared with the existing heat transfer correlation for the macrofin arrays. It is concluded that the existing macrocorrelation is no longer valid for the microfin arrays. Relevant empirical correlations for microfin arrays on the vertical and horizontal surfaces are presented based on the present experimental data.

• 한국시뮬레이션학회논문지
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• 제3권1호
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• pp.29-42
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• 1994

The architecture of a MIMD-type parallel computer system is specified: a simulator is developed to support design and evaluation of systems based on the architecture: and conducted with the simulator to evaluate system performance. The horizontal/vertical-bus(H/V-bus) system architecture provides an NxN array of processing elements which communicate with each other through a network of N horizontal buses and N vertical buses. The simulator, written in SLAM II and FORTRAN, is designed to provide high-resolution in simulating the IPC mechanism. Parameters provide the user with independent control of system size, PE speed and IPC mechanism speed. Results generated by the simulator include execution times, PE utilizations, queue lengths, and other data. The simulator is used to study system performance when a partial differential equation is solved by parallel Gauss-Seidel method. For comparisons, the benchmark is also executed on a single-bus system simulator that is derived from the H/V-bus system simulator. The benchmark is also solved on a single PE to obtain data for computing speedups. An extensive analysis of results is presented.

• 한국정보통신학회논문지
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• 제6권4호
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• pp.519-526
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• 2002

본 논문에서는 이동 목표물의 속도를 측정하기 위한 도플러 레이더용 중심 주파수 10.525GHz인 마이크 로스트립 패치 배열 안테나를 설계 및 제작하였다. 이동용 레이더 시스템에 적용하기 위해서 비교적 충격에 강한 단일기판을 사용하였고, 원하는 특성을 얻기 위하여 급전회로망은 corporated 3-dB amplitude taper를 이용하여 4 $\times$ 8로 배열하였다. 또한 정사각형의 패치 소자를 사용하여 원편파를 이용할 수 있도록 하였다. 설계 및 제작된 안테나는 반사계수(S$_1$$_1$) -53.498dB, 수평 빔폭 $10^{\circ}$, 수직 빔폭 $18.8^{\circ}$, 이득 21dBi 및 SLL(Side Lobe Level) -17.5 dB 이하, 220MHz의 VSMR 1.5 이하 대역폭을 얻었다.