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분기/접합 유한용량 폐쇄대기행렬망 일차모멘트 성능에 대한 이론적 고찰
백천현(Chunhyun Paik) 동의대학교 정보통신연구소 2005 정보통신연구지 Vol.6-2 No.-
In this study, we deal with closed fork/join queueing network with finite buffers and investigate the effects of changing network parameters on throughputs. Introducing the sample path technique, we first show that the departure times of customers at each server are also stochastic ordered, and hence the speeding up services improve the throughputs, and moreover we reveal that the throughput is monotone increasing with respect to buffer capacities regardless of service time distributions. Next, two throughput properties are also presented: the one is the symmetry property with respect to the number of customers and the other is the monotonicity with respect to the joint of buffer size and the number of customers. These properties will be useful in devising efficient algorithms for optimal designing problems.
OFDMA 무선통신시스템의 호접속 제어를 위한 SMDP 기반 최적화모형
백천현(Chunhyun Paik),정용주(Yongjoo Chung) 대한산업공학회 2012 산업공학 Vol.25 No.4
This study addresses the call admission control(CAC) problem for OFDMA wireless communication systems in which both subcarriers and power should be considered together as the system resources. To lessen the exccessive allocation of radio resources for protecting handoff calls, the proposed CAC allows the less data rate than their requirements to handoff calls. The CAC problem is formulated as a semi-Markov decision process(SMDP) with constraints on the blocking probabilities of handoff calls. Some extensive experiments are conducted to show the usefulness of the proposed CAC model.
인지라디오 네트워크에서 전력과 부반송파 할당을 위한 휴리스틱
백천현(Chunhyun Paik) 한국경영과학회 2012 經營 科學 Vol.29 No.2
With the explosivley increasing demand in wireless telecommunication service, the shortage of radio spectrum has been worsen. The traditional approach of the current fixed spectrum allocation leads to spectrum underutilization. Recently, CR (Cognitive Radio) technologies are proposed to enhance the spectrum utilization by allocating dynamically radio resources to CR Networks. In this study, we consider a radio resource(power, subcarrier) allocation problem for OFDMA-based CRN in which a base station supports a variety of CUs (CRN Users) while avoiding the radio interference to PRN (Primary Radio Network). The problem is mathematically formulated as a general 0-1 IP problem. The optimal solution method for the IP problem requires an unrealistic execution time due to its complexity. Therefore, we propose an heuristic that gives an approximate solution within a reasonable execution time.
상향식 모형을 이용한 국내 조선업의 온실가스 배출 분석
백천현(Chunhyun Paik),김후곤(Hugon Kim),김영진(Young Jin Kim),정용주(Yongjoo Chung) 한국경영과학회 2014 經營 科學 Vol.31 No.1
This study presents a bottom-up approach for analyzing greenhouse gas (GHG) emissions for the shipbuilding industry in Korea. The overall procedures for deriving GHG emissions from the Korean shipbuilding industry are presented. Based on the long-term forecast on energy demands of the Korean shipbuilding industry, reference energy system (RES) and energy balance (EB) for the shipbuilding process are derived for bottom-up modeling.
백천현(Paik Chunhyun),정용주(Chung Yongjoo),김영진(Kim Young Jin) 한국태양에너지학회 2024 한국태양에너지학회 논문집 Vol.44 No.1
The high volatility caused by the intermittent nature of wind power generation adds uncertainty to power grid systems. Herein, we analyzed the characteristics of domestic wind power output by focusing on the volatility of capacity factors. Initially, the average characteristics and the number and duration of ramps, which are representative measures of the volatility of the capacity factors, were analyzed by year and month, using the data for 2018 ~ 2022 with a temporal resolution of 1 h. Subsequently, we generated data at various resolution levels using the 2019 data with a temporal resolution of 5 min and analyzed how the number and duration of ramps were affected according to the resolution. The results showed that the frequency and duration of ramps strongly depended on the time resolution of the data, and that evaluating and considering ramp characteristics can assist in enhancing the flexibility of power system operations by mitigating rapid ramp events.
국내 태양광 발전의 용량크레딧 산정을 위한 이용률 기반 근사화 방법
백천현(Chunhyun Paik),정용주(Yong Joo Chung),김영진(Young Jin Kim) 한국태양에너지학회 2017 한국태양에너지학회 논문집 Vol.37 No.5
Solar power is expected to account for a considerable proportion of domestic renewable energy compared to other renewable energy sources. In this study, capacity credits, which are the most important factors for evaluating the effective capacity of photovoltaic power, are estimated by capacity factor-based approximation method. To do this, we use the data of solar power generation and capacity over many years and calculate the capacity factors of the domestic solar power. The results of the existing methods and ours proposed in this paper are compared and analyzed.
상향식 공정분석을 통한 국내 유리산업의 온실가스 인벤토리 산정
백천현(Chunhyun Paik),정용주(Yongjoo Chung),유종훈(Jonghoon Yoo) 한국경영과학회 2015 經營 科學 Vol.32 No.1
The glass production is classified into an energy intensive industry. This study develops a systematic procedure to derive Greenhouse Gas (GHG) emission inventory for the Korean glass industry. Based on the bottom-up approach in which the energy intensity in each production process is characterized, the EBs (energy balances) of glass production processes are derived. And the GHG emission is calculated for each of four types of glasses-flat glass, container glass, fiber glass, and LCD glass.