• 대한전자공학회논문지TC
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• 제41권8호
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• pp.63-68
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• 2004

채널 추정 오차가 존재하는 상황에서 MIMO 시스템의 채널 용량을 수식적으로 분석한다. 수식적인 분석에 의해, 채널 용량은 평균 신호 대 잡음비 (SNR) 와 함께 채널 추정 오차 (MSE)에 영향을 받음을 알 수 있다. 또한 본 논문에서는 평균 SNR 과 채널 용량의 손실량이 제한되어 있을 경우, 허용가능한 채널 추정 오차를 구함으로써 주어진 시스템에 적합한 채널 추정기법을 선택하는 기준을 제시한다. 실험 결과로부터 1 bps/Hz 채널용량의 손실에 대해 허용 가능한 채널 추정 오차는 20dB와 40dB의 평균 신호 대 잡음비에서 각각 10/sup -2/와 10/sup -4/임을 확인 할 수 있다.

• 융합신호처리학회논문지
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• 제12권3호
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• pp.188-193
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• 2011

본 논문에서는 OADF(Opportunistic Adaptive Decode-and-Forward) 릴레이 시스템에 대한 새로운 성능분석 기법을 레일리 페이딩 채널에 대하여 제안하였다. 제안된 분석 기법에서는 릴레이들의 복호 오류 사건(error-event)을 기반으로 수신된 순시 신호대 잡음비(Signal-to-Noise Ratio: SNR)를 표현한다. 또한 SNR의 확률 밀도 함수(Probability Density Function: PDF)를 기존의 분석 기법보다 일반적인 (PDF 표현에서 합 기호의 개수 및 그 영역이 구체화된)형태로 제시한다. 그리고 이를 이용하여 정확한 평균 오류율((Average Error Rate), 누락 확률(Outage Probability) 및 평균 채널용량(Average Channel Capacity)을 일반적인 형태로 유도한다. 제안된 성능분석 기법의 정확성은 모의실험을 통하여 검증한다. OADF 기법을 다른 기법들과 비교하여 평균 오류 확률, 누락 확률 및 채널 용량 측면에서 성능 향상 정도가 우수함을 확인하였다.

• 한국농공학회지
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• 제25권4호
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• pp.29-37
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• 1983

This study was carried out not only to prepare available materials that can be utilized in basic planning of irrigation reservoirs, but also to contribute to the study on countermeasures for reasonable irrigation water development in Korea in the future, through the investigation for the structural characteristics of reservoirs and their change trend by an epoch. During this study 123 sites of sample reservoirs were analysed in their dimensions of physical constituent factors. The physical characteristics and their change trends revealed by this study are summarized as follows: 1. For the irrigation earth dam in Korea the correlation between dam volume (v) and dam height & length (H$^2$L) can be described as the formula of v=1. 434H2L~17, 300 (r=0. 933), from which embankment amount is assumed to be quickly estimated under determined dam height and length of the proposed reservoir. 2. The ratio of dam volume to dam height & length ranges approximately from 0.5 to 3 (1.7 in average), that of storage capacity to dam volume 2 to 10 (8.4 in average), that of irrigation area to full water surface area 5 to 20 (13 in average) and that of catchment area to irrigation area 2 to 5 (4 in average). Though correlation between dam volume and dam height & length is high, that between others is relatively low. 3. Average storage depth ranges approximately from 4m to l0m (6.6m in average), unit storage capacity 0. 4m to 0. 8m (0.54 in average) and shape factor of dam 5 to 20 (10.5 in average). 4. The more recently planned the reservoirs were, the less storage capacity, dam volume, full water surface and dam shape factor they have. 5. The more recently planned the reservoirs were, the larger storage depth and unit storage capacity they have.

• 한국식품과학회지
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• 제22권7호
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• pp.805-811
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• 1990

대두단백질의 기능성을 개선하기 위하여 고정화된 트립신 및 키모트립신으로 가수분해시킨 후, 이 대두단백 가수물의 기능성을 조사하였다. Ferguson plot으로부터 가수분해물의 평균분자량 및 평균전하를 계산하여 대두단백의 기능성을 나타내는 인자로 이용하였다. 즉, 단백질의 평균분자량을 평균전하로 나눈 값은 단백가수물의 용해도, 포수력, 포유력, 유화도 등의 기능성을 예측하는데 이용될 수 있었다. 이 분자비가 낮으면 용해도는 향상되었으나 포수력은 감소되었으며 중간범위일 경우 포유력과 유화도는 증가되는 경향을 나타냈다.

• 수산해양기술연구
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• 제43권4호
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• pp.339-346
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• 2007

Estimating fishing capacity is one of current hot issues in the international fisheries. It is because that increased fishing capacity has caused not only fish stocks to be reduced, but also additional fishing costs to be incurred without additional incomes, which resulted in decrease of economically viability of fisheries. In order to solve this problem, FAO adopted 'the International Plan of Action for the Management of Fishing Capacity' in 1999 and recommended that member countries to measure fishing capacity and to implement the domestic action plan to reduce excess fishing capacity. This study is aimed at assessing fishing capacity of the octopus coastal trap fishery(OCTF) using data envelopment analysis(DEA) which is a method recommended by FAO. The DEA results on 10 individual OCTF vessels showed that the capacity utilization(CU) was a 0.93 on average, indicating some differences in CU among vessels(0.79-1.0). In addition, results of the sensitivity analysis revealed that under the current level of catch, the gross tonnage, horse power, days fished, and traps per trip could be reduced by 35%, 33%, 16%, and 18% on average, respectively.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.287-292
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• 1998

In particle or short-fiber reinforced composites. cracking of the reinforcements is a significant damage mode because the broken reinforcements lose load carrying capacity. This paper deals with the load carrying capacity of intact and broken ellipsoidal inhomogeneities embedded in an infinite body and a damage theory of particle or short-fiber reinforce composites. The average stress in the inhomogeneity represents its load carrying capacity. and the difference between the average stresses of the intact t and broken inhomogeneities indicates the loss of load carrying capacity due to cracking damage. The composite in damage process contains intact and broken reinforcements in a matrix. An incremental constitutive relation of particle or short-fiber reinforced composites including the progressive cracking damage of the reinforcements have been developed based on the Eshelby's equivalent inclusion method and Mori and Tanaka's mean field concept. Influence of the cracking damage on the stress-strain response of the composites is demonstrated.

• Journal of Communications and Networks
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• 제11권4호
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• pp.384-389
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• 2009

Optical wireless communication (OWC) systems are rapidly gaining popularity as effective means of transferring data at high rates over short distances. OWC facilitates rapidly deployable, lightweight, high-capacity communication without licensing fees and tariffs. Nevertheless, the performance of this new technology depends strongly on the atmospheric conditions and the characteristics of the link. In this work, we study the influence of these parameters on both the average (ergodic) capacity and the outage capacity of an OWC system over moderate to strong turbulence channels modeled by gamma-gamma distribution. Moreover, we compare the results that we obtain estimating the average and outage capacities.

• Geomechanics and Engineering
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• 제21권1호
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• pp.11-21
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• 2020

The traditional formulations for estimation of bearing capacity in rock mechanics assume a homogeneous and isotropic rock mass. However, it is common that the rock mass consists of different layers of different rock properties or of the same rock matrix with distinct geotechnical quality levels. The bearing capacity of a heterogeneous rock is estimated traditionally through the weighted average. In this paper, the solution of the weighted average is compared to the finite difference method applied to a bilayer rock mass. The influence of different parameters such as the thickness of the layers, the rock type, the uniaxial compressive strength and the overall geotechnical quality of the rock mass on the bearing capacity of a bilayer rock mass is analyzed. A parametric study by finite difference method is carried out to develop a bearing capacity factor in function of the layer thickness and the rock mass quality expressed in terms of the geological strength index, which is presented in a form of a chart. Therefore, this correlation factor allows estimating the bearing capacity of a rock mass that is formed by two layers with distinct GSI, depending on the bearing capacity of the rock mass formed only by the upper layer and considered by that way as homogenous and isotropic rock mass.

• 한국항만경제학회지
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• 제33권1호
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• pp.11-30
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• 2017

세계 해운기업들은 경영악화로 구조조정의 대상이 되고 있다. 세계컨테이너물동량 대비 세계컨테이너 선복량 과다가 주요 원인이다. 이는 세계컨테이너물동량 대비 필요한 선복량을 산출하는 기준이 없어 선복량을 조절할 수 있는 기능이 부족하기 때문이다. 이 연구는 "세계컨테이너선복량기준지수 'World Containership capacity (in TEU terms) Standards Index; WCSI'"와 "세계컨테이너선복량예측지수 'World Containership capacity (in TEU terms) Expected Index; WCEI'"란 용어와 지수를 개발하는 것이 목적이다. 개발 된 'WCSI'와 'WCEI'를 비교하면 아래와 같다. WCSI (평균항차 9.3) > WCEI 선복량 과잉 WCSI (평균항차 9.3) = WCEI 선복량 적정 WCSI (평균항차 9.3) < WCEI 선복량 부족 WCSI=HRCI $1000{\pm}150$ 근사치 'WCSI'와 'WCEI'를 이용하면 물동량대비 적절한 선복량을 산정할 수 있다. 그 결과 선박발주시기, 발주량 등을 예측할 수 있다. 'WCSI'와 'WCEI'를 계속 발전시켜 세계 해운기업 및 지원기업들이 효과적인 경영전략수립으로 위기를 극복하였으면 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권9호
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• pp.3016-3033
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• 2014

The downlink performance of distributed antenna systems (DAS) with antennas selection is investigated in Rayleigh fading multicell environment, and the corresponding system capacity and bit error rate (BER) analysis are presented. Based on the moment generating function, the probability density function (PDF) and cumulative distribution function (CDF) of the effective signal to interference plus noise ratio (SINR) of the system are first derived, respectively. Then, with the available CDF and PDF, the accurate closed-form expressions of average channel capacity and average BER are further derived for exact performance evaluation. To simplify the expression, a simple closed-form approximate expression of average channel capacity is obtained by means of Taylor series expansion, with the performance results close to the accurate expression. Besides, the system outage capacity is analyzed, and an accurate closed-form expression of outage capacity probability is derived. These theoretical expressions can provide good performance evaluation for DAS downlink. It can be shown by simulation that the theoretical analysis and simulation are consistent, and DAS with antenna selection outperforms that with conventional blanket transmission. Moreover, the system performance can be effectively improved as the number of receive antennas increases.