• 한국전자통신학회논문지
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• 제18권3호
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• pp.535-544
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• 2023

본 논문에서는 희망하는 빔포밍을 실현하기 위하여 LMS 알고리즘(반복법)을 이용하는 경우에 반복 계산과정에서 무게 분포를 조절하기 위한 기울기 벡터의 계산법(해석적인 방법, 중앙유한차분법)이 적응 빔포밍에 미치는 영향을 연구하였다. 이를 위하여 임의로 설정한 빔폭을 갖는 준이상 빔과 회전 빔, 그리고 멀티 빔을 예로 하여 검토하였다. 수치 실험은 적응 빔포밍 시스템에 임의의 초기치와 시행착오를 거쳐서 설정한 적절한 값의 스텝 파라미터를 두 계산법에 동일하게 적용하고, 기울기 벡터의 계산을 위한 두 가지 방법을 이용하여 적응성과 오차를 평가하는 목적 함수의 수렴 특성 등을 비교하였다.

• 대한기계학회논문집
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• 제15권2호
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• pp.604-610
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• 1991

In this paper, the weight functions for the Mode I and Mode II in SEN(single edge notched) specimen are obtained by superposition of the displacement in the singular field of the Buckner type and the displacements by opposite tractions induced by the singular field. The stress intensity factors, $K_{I}$ and $K_{II}$ are calculated by the weight function theory in SEN specimen under the loading equivalent to uniform tension and shear at infinity in Griffith crack. And the results are compared with the exact solutions.s.

• 한국소음진동공학회논문집
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• 제14권1호
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• pp.24-31
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• 2004

Recently, as the marine compressor power is increased, vibration problems on the marine vessel with V/W type reciprocating compressor have been occurred. A research on the balancing of marine V/W type reciprocating compressor has hardly been reported though a number of researches on the balancing of rotating machinery have been conducted. As a V/W type compressor has high capacity with long stroke, compact size and high center of gravity, It is easy to have a vibration problem by a little bit unbalanced force and moment. In this study, calculation methods for balance weight of the V/W type reciprocating compressors, which have different piston weight and asymmetry structure, are formulated. And their reliability were verified by comparing calculated balance weight with the experimental results of the real marine V/W type reciprocating compressors.

• 대한기계학회논문집A
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• 제20권7호
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• pp.2167-2173
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• 1996

An approximate weight function technique using the indirect boundary integral equation has been presented for the analysis of stress intensity foactors(SIFs) of a thick pipe. One-term boundary integral was introduced to represent the crack surface displacement field for the displacement based weight function technique. An explicit closed-form SIF solution applicable to symmetric cracked pipes without any modification of the solution including both circumferential and radial cracks has been derived. The necessary information in the analysis is two or three reference SIFs. In most cases the SIF solution were in good agreement with those available in the literature.

• 한국해양공학회지
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• 제23권1호
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• pp.146-151
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• 2009

In this paper, a weight function theory for the calculation of the mode III stress intensity factor in a rectilinear anisotropic body is formulated. This formulation employs Lekhnitskii's formalism for two dimensional anisotropic materials. To illustrate the method used for the weight function theory, we calculated the mode III stress intensity factor in a single edge-notched configuration.

• 한국구조물진단유지관리공학회 논문집
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• 제4권4호
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• pp.211-218
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• 2000

Many bridges are severely damaged by the overloaded heavy vehicle and the trend will become more serious because the traffic volume is continuously increasing. Currently, the vehicles with gross weights over 40 tonf or axle weight over 10 tonf are not allowed on the public road. However, this regulation is not based on a systematic study on the bridge capacity and assumed to be much too conservative depending on the vehicle types and bridge types. In this study, the permit weights of heavy vehicles of diverse axle spacings and axle load distribution are calculated considering the structural characteristics of bridge superstructures. In order to consider the various load effects of heavy weight vehicle crossings, three conditions are considered in the calculation of permit vehicle load. From the results, the permit vehicle weights of the simple girder bridges are calculated.

• 전자공학회논문지
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• 제51권11호
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• pp.66-72
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• 2014

Histogram of oriented gradient (HOG) 특징은 영상 기반 보행자 인식에서 널리 사용되고 있다. HOG 특징을 이용한 보행자 인식의 인식률을 높이는데 가장 중요한 역할을 하는 것은 보간 기술이다. HOG 특징 연산에 보간 기술을 적용하기 위해서는 각 픽셀의 기울기 방향에 가장 근접한 두 개의 기울기 방향 bin과 가중치를 계산해야 한다. 따라서 본 논문에서는 HOG 특징 연산에 적용하기 위한 효율적인 기울기 방향 bin 및 가중치 연산 회로를 제안한다. 제안하는 회로는 탄젠트 함수와 나눗셈 연산을 피하기 위해 미리 계산된 값을 테이블로 지정하여 사용하였으며, 탄젠트 함수와 가중치 값의 특성을 이용함으로써 회로 내 테이블의 크기를 최소화하였다. 또한 처리 속도 향상을 위해 파이프라인 구조를 적용하였으며, 효율적인 coarse 및 fine 탐색 방법을 적용하여 각 픽셀에 대한 기울기 방향 bin과 가중치를 두 클락 사이클 내에 계산한다. 본 논문에서 제안하는 회로는 $1^{\circ}$ 단위로 기울기 방향을 계산하여 기울기 방향 bin과 가중치를 모두 결정하기 때문에 HOG 특징을 위한 보간 기술에 적용되어 높은 인식률을 제공하기 위해 사용될 수 있다.

• 기술사
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• 제2권6_7호
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• pp.12-23
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• 1969

The purpose of this study is to find out the reasonable amount of evapo-transpiration required for the paddy rice plant during the whole growing season. So, on the basis of the 3year experimental data concerning the evapo-transpiration from 1966 to 1968, the author obtained the following results. 1) The leaf area index in the densely planted plot is generally higher than that in the conventionally planted one during the first half of growing season. So, the coefficient of transpiration in the former plot is some what higher than in the latter, and the coefficient of water surface evaporation under the plant cover has the inverse relation between both plots. 2) It is unreasonable that coefficient of evapo-transpiration is applied to the calculation of the evapo-transpiration requirments of each growing stage, because a certain degree of variation in meteorological factors and in the thickness of the plant growth is involved in it. 3) It is most reasonable that the rate of transpiration and of the water surface evaporation is applied to the calculation of the transpirated amount and evaporated one in each growing stage because it shows almost constant value in spite of any meteorological conditions in so far as the variety of rice, planted density and control of applying fertilizer are same and the disease and blight are negligible. 4) The ratio of the amount of transpiration to the weight of the whole air dried yields has the tendency of decreasing as that of the yields increase, having almost constant value despite the amount of pan evaporation; and the value is about 210 when the weight of root parts is included to that of the yields. 5) Although the required amount of transpiration during the whole growing season can be calculated with the above ratio, fig. 7 showing the relation between the amount of transpiration and the weight of the yields is more reasonable and will be convinient to find it. And the requirements of water surface evaporation during the same season can also be directly found with the weight of air dried straw refering to fig.8.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 공동학술발표회
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• pp.231-231
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• 2017

• 한국컴퓨터정보학회논문지
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• 제16권5호
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• pp.101-107
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• 2011

본 논문에서는 적응 배열 안테나 시스템에서 간섭 및 재밍 신호를 제거하기 위해서 최적 가중 벡터를 연구하였다. 최적 가중 벡터는 선형 제한 조건에서 최소 분산 알고리즘과 비용함수를 적용시켜 구하였고, 목표물의 신호를 정확히 추정하였다. 적응 배열 안테나 시스템은 간섭 및 재머전력을 감소시키고 신호대 잡음비를 향상시키는 시스템이다. 적응 배열 안테나 시스템은 각 안테나 배열 소자의 출력이 탭(Tap)을 거쳐 지연되고 각 탭에 복소 가중치가 곱해져서 최종적으로 하나의 복합신호를 만든다. 최적의 가중치를 구하기 위해서 본 논문에서는 입력 공분산 행렬의 최적 가중벡터를 이용하였다. 본 논문에서 제안된 알고리즘으로 모의 실험한 결과 분해능은 $3^{\circ}$이하로 향상되었으며 부엽은 약 10 dB 감소하였음을 입증하였다.