• 제목/요약/키워드: Optimization of Operation Conditions

검색결과 221건 처리시간 0.026초

철도편익 증대를 위한 소요차량수 산정 방안 (Estimation of the Optimum Number of Rail Cars to Increase the Benefit)

  • 김경태;이진선;박범환
    • 한국철도학회논문집
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    • 제13권3호
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    • pp.333-338
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    • 2010
  • 철도투자사업의 경제성 증대를 위해서는 새로운 편익의 발굴도 중요하지만 비용 부문에서 과다하게 책정되는 부분을 개선하는 것도 매우 중요하다. 본 논문은 철도부문의 편익을 제고하기 위해 철도차량의 정차 패턴까지 고려한 최적화 모형을 이용하여 분석할 것을 제안한다. 기존의 방법은 주요 역에 모두 정차한다는 시나리오를 토대로 운행시간을 작성하였으나 이는 실제 운행 여건과는 맞지 않는다. 열차별 정차 패턴을 고려하여 소요 차량수를 산정할 경우 계획 단계에서 적용되는 차량구입비를 합리적으로 산정할 수 있고 경제성 분석에도 긍정적인 영향을 주는 것으로 분석되었다.

SimulationX를 이용한 트랙터 PST 변속 충격 최소화 연구 (Minimization of Shifting Shock of Tractor PST using SimulationX)

  • 엄태호;이철희
    • 드라이브 ㆍ 컨트롤
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    • 제15권3호
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    • pp.36-42
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    • 2018
  • Agricultural tractors require frequent shifting to improve operation efficiency, and PST (Powershift Transmission) is considered as a suitable transmission. However, due to the inherent characteristics of the PST, shocks arise during shifting, which imparts a negative effect on the operator. Therefore, in order to improve the transmission performance of the tractor PST, researches on various methods including the hydraulic system circuit, the engine input speed control, and the mechanical system of the transmission are steadily being conducted. In this study, in order to reduce the impact of PST on a shift based on SimulationX software, we analyzed the characteristics of the input signal of PCV (Pressure Control Valve) through sensitivity analysis and verified the simulation model through actual vehicle test. Optimization was performed for minimizing the shift shock for some of the parameters of the input signal at constant temperature and RPM conditions.

프로판 엔진의 배기 포트에서 탄화수소 산화 예측을 위한 모델링 (Prediction Modeling of Unburned Hydrocarbon Oxidation in the Exhaust Port of a Propane-Fueled SI Engine)

  • 이형승;박종범;최회명;민경덕;김응서
    • 한국자동차공학회논문집
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    • 제8권2호
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    • pp.33-40
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    • 2000
  • In order to investigate the exhaust structure and secondary oxidation of unburned hydrocarbon (HC) in the exhaust port, a numerical simulation was performed with 3-dimensional flow model and oxidation mechanism optimized for port oxidation. To predict the exhaust and oxidation process with consideration of flow, mixing, and temperature, 3-dimensional flow model and HC oxidation model were used with a commercial computational program, STAR-CD. The flow model were with moving grid for valve motion, which could predict the change of flow field with respect to valve lift. Optimization was performed to predict the HC oxidation with temperature range of 1200~1500K, low HC and oxygen concentration, existence of intermediate species, as typical in port oxidation. The constructed model could predict the port oxidation process with oxidation degree of 14~48% according to the engine operation conditions.

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A Metadata-enabled Approach for Scalable Video Streaming in Heterogeneous Networks

  • Thang, Truong Cong;Le, Hung T.;Nguyen, Duc V.;Pham, Anh T.
    • Journal of Multimedia Information System
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    • 제2권1호
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    • pp.153-162
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    • 2015
  • In today's pervasive computing environments, multimedia content should be adapted to meet various conditions of network connections, terminals, and user characteristics. Scalable Video Coding (SVC) is a key solution for video communication over heterogeneous networks, where user terminals have different capabilities. This paper presents a standard-compliant approach that adapts an SVC bitstream to support multiple users. The adaptation problem is formulated as an optimization problem, focusing on the tradeoff between qualities of different spatial layers of an SVC video. Then the adaptation process is represented by standard metadata of MPEG-21, which can be solved by universal processing to enable interoperable and automatic operation. Our approach provides the users with optimal quality, a wide flexibility, and seamless adaptation. To the best of our knowledge, this is the first study that shows the adaptation tradeoff between spatial layers of a conforming SVC bitstream.

구멍이 있는 공작물의 가공시 형상특성 (Geometric Characteristics on Workpiece with Hole in Face Milling)

  • 이종선;원종진;안운상;홍석주;윤희중
    • 한국공작기계학회논문집
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    • 제11권5호
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    • pp.1-6
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    • 2002
  • This study is to investigate the characteristics of the surface around a hole on inlet and outlet of product which are manufactured by face mill or end mill cutting with a hole or a pocket in its surface. Furthermore, experiments for optimization of process conditions to minimize the change of characteristics of milling cut surface after a hole cutting operation are implemented. This result is apply to manufacture of mold products and metal products by diecasting.

마코프 누적 프로세스에서의 확률적 콘벡스성 (Stochastic convexity in markov additive processes)

  • 윤복식
    • 한국경영과학회:학술대회논문집
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    • 대한산업공학회/한국경영과학회 1991년도 춘계공동학술대회 발표논문 및 초록집; 전북대학교, 전주; 26-27 Apr. 1991
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    • pp.147-159
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    • 1991
  • Stochastic convexity(concvity) of a stochastic process is a very useful concept for various stochastic optimization problems. In this study we first establish stochastic convexity of a certain class of Markov additive processes through the probabilistic construction based on the sample path approach. A Markov additive process is obtained by integrating a functional of the underlying Markov process with respect to time, and its stochastic convexity can be utilized to provide efficient methods for optimal design or for optimal operation schedule of a wide range of stochastic systems. We also clarify the conditions for stochatic monotonicity of the Markov process, which is required for stochatic convexity of the Markov additive process. This result shows that stochastic convexity can be used for the analysis of probabilistic models based on birth and death processes, which have very wide application area. Finally we demonstrate the validity and usefulness of the theoretical results by developing efficient methods for the optimal replacement scheduling based on the stochastic convexity property.

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전력시스템 안정화를 위한 GA를 이용한 SPS제어기 설계 (Design of a GA-based SPS controller for Power system stabilization)

  • 이창우;김상효;정형환;이정필;김해재
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2003년도 하계학술대회 논문집 A
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    • pp.224-226
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    • 2003
  • Design of a GA-based SPS controller for Power system stabilization has been investigated in this paper. The design problem of SPS controller is formulated as an optimization problem using GA. The dynamic characteristic responses are considered to verify performance of the proposed SPS under various disturbance for various operation conditions. The simulation results show that the proposed SPS controller provides most of the damping and improves greatly the voltage profile of the system under two different disturbances.

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증기발생기 수위 제어를 위한 견실$H^{\infty}$ 제어기 설계 (Design of Robust $H^{\infty}$ Controller for Water Level Control of Steam Generator)

  • 서성환;조희수박홍배
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 1998년도 하계종합학술대회논문집
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    • pp.223-226
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    • 1998
  • The control objective of steam generator water level in the secondary circuit of a nuclear power plant is to regulate the water level at the desired set point. The dynamics of steam generators is non-linear in nature. The task of modelling such plant is very difficult and especially so when plant operating conditions change frequently. In these reasons, conventional PI gains over all pover range will not work efficiently and a manual control is generally used in low power operation. Therefore the robust H$\infty$ controller design method should be required. In this paper, we design the robust H$\infty$ controller for water level control of steam generator using a mixed H$\infty$ optimization with model-matching method. Firstly we choose the desired model that has good disturbance rejection performance. Secondly we design a stabilizing controller to keep the model-matching error small and also provide sufficiently large stability margin against additive perturbations of the nominal plant.

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P형 우물 영역에 따른 4H-SiC DMOSFETs의 스위칭 특성 분석 (Effect of P-Base Region on the Transient Characteristics of 4H-SiC DMOSFETs)

  • 강민석;안정준;성범식;정지환;구상모
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2010년도 하계학술대회 논문집
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    • pp.352-352
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    • 2010
  • Silicon Carbide (SiC) power device possesses attractive features, such as high breakdown voltage, high-speed switching capability, and high temperature operation. In general, device design has a significant effect on the switching characteristics. In this paper, we report the effect of the P-base doping concentration ($N_{PBASE}$) on the transient characteristics of 4H-SiC DMOSFETs. By reducing $N_{PBASE}$, switching time also decreases, primarily due to the lowered channel resistance. It is found that improvement of switching speed in 4H-SiC DMOSFETs is essential to reduce the and channel resistance. Therefore, accurate modeling of the operating conditions are essential for the optimization of superior switching performance.

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마코프 누적 프로세스에서의 확률적 콘벡스성과 그 응용 (Stochastic convexity in Markov additive processes and its applications)

  • 윤복식
    • 한국경영과학회지
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    • 제16권1호
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    • pp.76-88
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    • 1991
  • Stochastic convexity (concavity) of a stochastic process is a very useful concept for various stochastic optimization problems. In this study we first establish stochastic convexity of a certain class of Markov additive processes through probabilistic construction based on the sample path approach. A Markov additive process is abtained by integrating a functional of the underlying Markov process with respect to time, and its stochastic convexity can be utilized to provide efficient methods for optimal design or optimal operation schedule wide range of stochastic systems. We also clarify the conditions for stochastic monotonicity of the Markov process. From the result it is shown that stachstic convexity can be used for the analysis of probabilitic models based on birth and death processes, which have very wide applications area. Finally we demonstrate the validity and usefulness of the theoretical results by developing efficient methods for the optimal replacement scheduling based on the stochastic convexity property.

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