• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2011년도 학술발표회
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• pp.252-252
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• 2011

Rainfall-runoff models are calibrated and validated by using a same data set such as observations. The past climate change effects the present rainfall pattern and also will effect on the future. To predict rainfall-runoff more preciously we have to consider the climate change pattern in the past, present and the future time. Thus, in this study, the climate change represents changes in mean precipitation and standard deviation in different patterns. In some river basins, there is no enough length of data for the analysis. Therefore, we have to generate the synthetic data using proper distribution for calculation of precipitation based on the observed data. In this study, Kajiyama model is used to analyze the runoff in the dry and the wet period, separately. Mean and standard deviation are used for generating precipitation from the gamma distribution. Twenty hypothetical scenarios are considered to show the climate change conditions. The mean precipitation are changed by -20%, -10%, 0%, +10% and +20% for the data generation with keeping the standard deviation constant in the wet and the dry period respectively. Similarly, the standard deviations of precipitation are changed by -20%, -10%, 0%, +10% and +20% keeping the mean value of precipitation constant for the wet and the dry period sequentially. In the wet period, when the standard deviation value varies then the mean NSE ratio is more fluctuate rather than the dry period. On the other hand, the mean NSE ratio in some extent is more fluctuate in the wet period and sometimes in the dry period, if the mean value of precipitation varies while keeping the standard deviation constant.

• 한국위성정보통신학회논문지
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• 제8권1호
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• pp.8-13
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• 2013

다양하고 많은 발사체를 효과적으로 운영하기 위해서 우리의 실정에 맞는 차세대 FTS(Flight Termination System)를 선정해서 개발할 필요가 있다. 차세대 FTS 방식으로는 Standard 톤, Secure 톤, MHA(Modified High Alphabet), EFTS(Enhanced FTS) 그리고 DSSS(Direct Sequence Spread Spectrum)가 검토되고 있다. FTS는 사용 목적 때문에 우수한 성능과 높은 신뢰성을 필요로 하며, 소요 수량이 적은 반면에 가격은 고가이다. 때문에 차세대 FTS의 방식을 선정해서 새로운 FTS를 도입하더라도 현재 사용하고 있는 시스템의 주요 구성품의 재사용 가능성 여부도 검토할 필요가 있다. 특히 송신기의 주요 구성품인 전력증폭기는 반드시 재사용 가능성을 검토할 필요가 있다. 신호의 CCDF(Complementary Cumulative Distribution Function)는 신호의 평균전력에 대한 첨두전력의 비를 빈도로 나타낸 것이므로 전력증폭기나 송신기의 성능을 나타낼 때 주로 사용한다. 본 논문에서는 전력증폭기의 재사용 가능성을 검토하는 방법으로 송신신호의 CCDF를 시뮬레이션해서 비교하는 방법을 이용하였다. CCDF 시뮬레이션 결과 Standard 톤의 PEP(Peak Envelop Power)는 0.21dB로 계산되었으며, Secure 톤과 MHA은 송신신호가 Standard 톤과 같기 때문에 동일한 PEP를 갖는다. CPFSK 변조를 이용하는 EFTS의 경우에 PEP는 1.81dB 였으며, BPSK 변조를 이용하는 DSSS의 경우에는 2.6dB로 계산되었다.

• Communications for Statistical Applications and Methods
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• 제19권1호
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• pp.169-175
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• 2012

The sensitivity of the performance measures such as the mean and the standard deviation of the queue length and the blocking probability with respect to the moments of the service time are numerically investigated. The service time distribution is fitted with phase type(PH) distribution by matching the first three moments of service time and the M/G/c retrial queue is approximated by the M/PH/c retrial queue. Approximations are compared with the simulation results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.422_423
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• 2009

DNP 3.0 is the most widely used data communication protocol for electric power control systems. KEPCO(Korea Electric Power Corporation) also uses DNP 3.0 as a data transmission protocol for the DAS(Distribution Automation System) and the SCADA system of the transmmission system. But DNP 3.0 is one of the oldest industrial standard having many restrictions and there are many considerations for optimal design of DNP 3.0 network for the Distribution Automation System.

• Management Science and Financial Engineering
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• 제5권2호
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• pp.25-41
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• 1999

This paper generalizes the classic two-stage multicommodity distribution system design problem to the one that includes plant locations as well as distribution center locations. Accommodating plant location leads to subproblems which are mixed are mixed integer. Hence. no LP-type subproblems are avail-able, and therefore standard Benders decomposition no longer applies. We develop new solution method which combines an integer L-shaped method with Benders decomposition to suit the purpose, and pre-sent the test results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 B
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• pp.640-642
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• 1999

Recent work within the DNP work group has resulted in the proposal, DNP 3.0, as the informative interface for distribution automation systems. This proposed standard embodies the generic principles developed and used within generic protocol. This paper describes a compliance test procedure specifically for Distribution Automation System, practical experience.

• 충청수학회지
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• 제15권1호
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• pp.87-94
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• 2002

Trot(1999) considered how to calculate the expected area of a random triangle in the unit square $[0,1]{\times}[0,1]$. He used the Mathematica software package for the computational part. In this article, we study various aspects of the probability distribution of a triangle randomly chosen inside the circle of radius r. A simulation activity that can be conducted in statistics and probability classrooms is also considered.

• Communications for Statistical Applications and Methods
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• 제10권1호
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• pp.203-210
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• 2003

In a standard Metropolis-type Monte Carlo simulation, the proposal distribution cannot be easily adapted to "local dynamics" of the target distribution. To overcome some of these difficulties, Duane et al. (1987) introduced the method of hybrid Monte Carlo(HMC) which combines the basic idea of molecular dynamics and the Metropolis acceptance-rejection rule to produce Monte Carlo samples from a given target distribution. In this paper, using the HMC within Gibbs sampler, an asymptotical estimate of the smoothing mean and a general solution to state space modeling in Bayesian framework is obtaineds obtained.

• 산업경영시스템학회지
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• 제16권28호
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• pp.137-143
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• 1993

Generally there are three methods to derive an approximation formula: 1) approching standard normal distribution by appropriate changing variable 2) using standardization variable for expansion 3) deriving approximation formula by direct method. This paper present correction terms having the form of $C_{1/v^{n/2}}/{\;}+{\;}C_2{\;}(n=1,2)$ with respect to $x^2_{\alpha}(v)$ distribution (${\nu}{\;}{\leq}{\;}30$), which minimize the error by EDA method and least square method.

• 한국신뢰성학회지:신뢰성응용연구
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• 제3권2호
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• pp.137-143
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• 2003

Sequential test plans are characterized by decision rules for accepting or rejecting compliance, or continuing the test at my test time. They are determined by selected values of risks and discrimination ratio. The sequential test plans in the international standard such as MIL-HDBK-781A are based on the assumption that the underlying distribution of times between failures is exponential. In this paper, sequential test plans are extended to the Weibull distribution case. Simulation studies are performed to examine the reasonability in this extension.