• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2003년도 통신소사이어티 추계학술대회논문집
• /
• pp.15-19
• /
• 2003

In this paper, the bit error rate (BER) performance of the fast frequency hopping/M-ary frequency shift keying system using the clipper receiver is analyzed by using the characteristic function (CF) technique in the presence of n=1 band multitone jamming and additive white Gaussian noise environment. The CFs of the clipper receiver outputs are derived as a infinite series representation using Gamma function and Marcum's Q -function. The analytical results are validated with various simulation results. Performance comparisons with linear combining receiver are shown that the BER performance of the clipper receiver is much better than that of the linear combining receiver In addition, as the clipping level approaches to infinity, it is shown that the clipper receiver simply performs a linear combining without clipping and there exists an optimum value of diversity level (the number of hops per symbol) that maximizes the worst case BER performance of the clipper receiver.

• 한국전산유체공학회지
• /
• 제14권2호
• /
• pp.1-8
• /
• 2009

The purposes of present work are to analyze the convective heat transfer with three-dimensional Reynolds-averaged Navier-Stokes analysis, and to optimize shape of the mixing vane taken tolerance into consideration by using the analysis results. Response surface method is employed as an optimization technique. The objective function is defined as a combination of heat transfer rate and inverse of pressure drop. Two bend angles of mixing vane are selected as design variables. Thermal-hydraulic performances have been discussed and optimum shape has been obtained as a function of weighting factor in the objective function. The results show that the optimized geometry improves the heat transfer performance far downstream of the mixing vane.

• 천문학회지
• /
• 제16권2호
• /
• pp.43-54
• /
• 1983

The present day mass functions of main sequence stars in the well observed open clusters, Hyades, Praesepe, Pleiades, NGC 654 and NGC 6530 arc derived and compared with those computed from the model of time-dependent initial mass function and star formation rate. The agreements between the observed and computed present day mass functions suggest the importance of fragmentation process at the early phase and fragment interaction at the later phase of cluster evolution. This process of star formation is different from that related to the evolution of the solar neighborhood, and also could explain the lack of low mass stars observed in some open clusters.

• 한국컴퓨터그래픽스학회논문지
• /
• 제6권4호
• /
• pp.15-22
• /
• 2000

영상기반 모델링 및 렌더링의 주된 흐름중의 하나는 plenoptic function을 어떻게 구현할 것인가에 집중되고 있다. 본 논문은 임의의 위치에 배치된 파노라마 군을 이용하여 plenoptic function을 구현하는 새로운 기법을 제안한다. 이 기법은 우선 간단한 컴퓨터 비전 기술을 사용하여 주변 환경에 대한 개괄적인 깊이 정보를 추출한 뒤, 이를 이용하여 파노라마 영상 데이터를 보정/보간하여 새로운 시점에서의 렌더링을 수행한다. 본 기법을 사용한 결과 실시간에 부드러운 네비게이션을 구현할 수 있었다.

• Journal of Communications and Networks
• /
• 제18권1호
• /
• pp.19-26
• /
• 2016

In this paper, the performance of dual-hop multi-relay maximum ratio transmission (MRT) over Rayleigh flat fading channels is studied with both conventional (all relays participate the transmission) and opportunistic (best relay is selected to maximize the received signal-to-noise ratio (SNR)) relaying. Performance analysis starts with the derivation of the probability density function, cumulative distribution function and moment generating function of the SNR. Then, both approximate and asymptotic expressions of symbol error rate (SER) and outage probability are derived for arbitrary numbers of antennas and relays. With the help of asymptotic SER and outage probability, diversity and array gains are obtained. In addition, impact of imperfect channel estimations is investigated and optimum power allocation factors for source and relay are calculated. Our analytical findings are validated by numerical examples which indicate that multi-relay MRT can be a low complexity and reliable option in cooperative networks.

• 융합신호처리학회논문지
• /
• 제3권1호
• /
• pp.48-53
• /
• 2002

본 논문에서는 무제약 필기체 숫자 인식에 있어서 향상된 RBF(Radial Basis Function) 신경망을 이용한 새로운 접근 방법을 제시하였다. RBF 신경망은 인식률과 인식 속도를 향상시키기 위해 기저 함수로서 Raised Cosine RBF를 사용하였다. Raised Cosine RBF 신경망 분류기의 성능 평가를 위하여 캐나다 몬트리올 Concordia 대학의 무제약 필기체 숫자 데이터베이스를 사용하였고, 실험 결과 98.05%의 인식률을 보였다.

• 수산경영론집
• /
• 제49권4호
• /
• pp.19-36
• /
• 2018

Overstock in aquaculture is a matter of concern in aquaculture management. To sort fish based on fingerling size in case of overstocking is an important problem in aquaculture farm. This study aims to determine the amount of fry overstock and sorting time in aquaculture farm. This study builds a mathematical model that finds the value of decision variables to optimize objective function summing up the fingerling purchasing cost, aquaculture farm operating cost and feeding cost under mortality and farming period constraints. The proposed mathematical model involves following biological and economical variables and coefficients: (1) number of fingerlings, (2) sorting time, (3) fish growth rate and variation, (4) mortality, (5) price of a fry (6) feeding cost, and (7) possible sorting periods. Numerical simulation is presented herein. The objective of numerical simulation is to provide decision makers to analyse and comprehend the proposed model. When extensive biological data about growth function of fry becomes available, the proposed model can be widely applicable to real aquaculture farms.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2019년도 추계 학술논문 발표대회
• /
• pp.60-61
• /
• 2019

Concrete carbonation is one of the factors that reduce the durability of concrete. In modern times, due to industrialization, the carbon dioxide concentration in the atmosphere is increasing, and the impact of carbonation is increasing. So, it is important to understand the carbonation resistance according to the concrete compounding to secure the concrete durability life. In this study, we want to predict the concrete carbonation velocity coefficient, which is an indicator of the carbonation resistance of concrete, through the deep learning algorithm, and to find the activation function suitable for the prediction of carbonation rate coefficient as a process to determine the learning accuracy through the deep learning algorithm. In the scope of this study, using the ReLU function showed better accuracy than using other activation functions.

• 한국분무공학회지
• /
• 제26권4호
• /
• pp.182-188
• /
• 2021

In this paper, using a transfer function-based analytical model, major factors influencing the acoustics and combustion instability in a two-stage duct system composed of a nozzle and a combustor were derived and their quantitative effects were evaluated. From the acoustic analysis, it was confirmed that the change in reflection coefficient and mean flow could have a great influence on the instability growth rate, and the area ratio and speed of sound ratio between the nozzle and the combustor are also key parameters to determine combustion instability as well as flame transfer functions.

• 한국BIM학회 논문집
• /
• 제12권2호
• /
• pp.40-48
• /
• 2022

It is very important to accurately predict construction costs in the early stages of the construction project. However, it is difficult to accurately predict construction costs with limited information from the initial stage. In recent years, with the development of machine learning technology, it has become possible to predict construction costs more accurately than before only with schematic construction characteristics. Based on machine learning technology, this study aims to analyze plans to more accurately predict construction costs by using only the factors influencing construction costs. To the end of this study, the effect of the error rate according to the activation function and the node configuration of the hidden layer was analyzed.