• International Journal of Highway Engineering
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• v.16 no.2
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• pp.119-129
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• 2014

PURPOSES : The purpose of this study is to develop the U-turn accident model at 4-legged signalized intersections in urban areas. METHODS : In order to analyze the characteristics of the accidents which are associated with U-turn operation at 4-legged signalized intersections in urban areas and develop an U-turn accident model by regression analysis, the tests of overdispersion and zero-inflation are conducted about the dependent variables of number of accidents and EPDO (Equivalent Property Damage Only). RESULTS : As their results, the Poisson model fits best for number of accident and the ZIP (Zero Inflated Poisson) fits best for EPOD, the variables of conflict traffic, width of opposing road, traffic passing speed are adopted as independent variable for both models. The variables of number of bus berths and rate of U-turn signal time at which the U-turn is permitted are adopted as independent variable only for EPDO. CONCLUSIONS : These study results suggest that U-turn would be permitted at the intersection where the width of opposing road is wider than 11.9 meters, the passing vehicle speed is not high and U-turn operation is not hindered by the buses stopping at bus stops.

• The Journal of Information Technology
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• v.7 no.2
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• pp.19-28
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• 2004

Many kind of operators using Residue Number System are used to design the special purpose processor for many merits in Digital Signal Processing, Computer Graphics, etc. But It get demerits for general division and the magnitude comparison. In this paper, general division operator for divisor with a small number in RNS is proposed. If the result of division using the multiplicative inverse has remainder, the quotient of this is larger than maximum quotient of division that has the same divisor to dividend of the maximum size. This condition is used for the ending condition of the recursive operation. And, the divisor is substitute for the compared value of quotients. So, the proposed division operator has a small size and fine operation speed, but with the limitation of divisor.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.3-4
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• 2011

This paper presents a survey of floating power supply based on bootstrap operation for three-level voltage-source inverters. The floating power supply for upper switches is achieved by the bootstrap capacitor charged during on-time of the switch underneath. Hence, a large number of bulky isolated DC/DC power supplies for each gate driver are reduced. The Pspice simulation results show the behavior of bootstrap devices and the performance of bootstrap capacitor voltage.

• Journal of information and communication convergence engineering
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• v.6 no.3
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• pp.285-288
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• 2008

Most of multimedia processors for 2D/3D graphics acceleration use a lot of integer/floating point arithmetic units. We present a new architecture with an efficient ALU, built in a smaller chip size. It reduces instruction cycles significantly based on a foundation of multi-thread operation, variable length instruction words, dual phase operation, and phase instruction's coordination. We can decrease the number of instruction cycles up to 50%, and can achieve twice better performance.

• Proceedings of the Korea Society for Simulation Conference
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• 1997.04a
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• pp.124-127
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• 1997

A key element in the control of Automated Guided Vehicle Systems (AGVS) is dispatching policy. This paper proposes a new dispatching algorithm for an efficient operation of AGVS. Based on an evolutionary operation, it has an adaptive control capability responding to changes of the system environment. The performance of the algorithm is compared with some well-known dispatching rules in terms of the system throughput through simulation. Sensitivity analysis is carried out varying the buffer capacity and the number of AGVS.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.1121-1124
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• 1993

We propose two-degree-of-freedom fuzzy neural network control systems. It has a hierarchical structure of two sets of control knowledge, thus it is easy to extract and refine fuzzy rules before and after the operation has started, and the number of fuzzy rules is reduced. In addition an example application of automatic vehicle operation is reported and its usefulness is shown simulation.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2208-2218
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• 2017

To resolve overload in a distribution system, a distribution system operator (DSO) often performs a load transfer using normally open tie points and switches in the distribution line. During this process, the distribution system is momentarily operated in closed-loop operation. A closed-loop current in the distribution system can cause a power failure due to excess breaking current in the circuit breakers and reclosers. Therefore, it is necessary to calculate the closed-loop current exactly. However, if there are a large number of distributed generation (DG) systems in the distribution system, such as energy storage systems (ESS), they might obstruct the closed-loop operation based on bidirectional power flow. For quick and precise operation of a closed-loop system, the ESS has to regulate the power generation while satisfying closed-loop operation in the worst cases. We propose a strategy for balanced power regulation of an ESS. Simulations were carried out using PSCAD/EMTDC, and the results were compared with calculation results.

• Journal of Korean Port Research
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• v.11 no.1
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• pp.45-64
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• 1997

Ship's delay caused by port congestion has drawn attention to the necessity for analysis on overall operation in port. But, in order to analyze the complicated port operation which contains large number of variable factors, queueing theory is needed to be adopted, which is applicable to a large scale transportation including ship's arrival in a large port. In this paper, a simulation model for Inchon Port was developed by the software SIMAN V and presented congestion rate under a certain scenario regarding the arrival ship's number and service levels. To develop the simulation model, types of ships and cargoes during the 1995 in Inchon Port was analyzed in advance. The results of the simulation can be summarized as follows : In order to maintain present levels of congestion rate and time with the increasing number of arrival vessels, service rate should be increased at an exponential rate. To improve the current congestion effectively, part of cargoes are needed to be transferred to a newly developing port. Results obtained from simulation can be used properly to prepare improved service levels and to plan appropriate investment strategies.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.12
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• pp.641-648
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• 2003

This paper proposes a novel UPFE based on H-bridge modules, isolated through single-phase multi-winding transformers. The dynamic performance of proposed system was analyzed by simulation with EMTDC, assuming that the UPFC is connected with the 138-kV transmission line of one-machine-infinite-bus power system. The proposed system can be directly connected to the transmission line without series injection transformers. It has flexibility in expanding the operation voltage by increasing the number of H-bridge modules.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.81-86
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• 1991

The iterative learning operation has been utilized in the temperature Control of a batch reactor. A generic form of feedback-assisted first-order learning control scheme was constructed and then various design and operation modes were derived through convergence and robustness analysis in the frequency domain. The proposed learning control scheme was then implemented on a bench scale batch reactor with the heat of reaction simulated by an electric heater. The results show a great improvement in the performance of control as the number of batch operations progressed.