• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.729-731
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• 2000

This paper presents a simple method for determining the minimum value of capacitance required for initiating self excitation in three-phase self-excited induction generator. Based on the steady-state equivalent circuit model, this paper presents simple and direct method to find the minimum capacitance requirement under R-L load. Using the loop impedance and nodal admittance. the minimum capacitance is determined by self excitation condition. These computed values can be used to predict practically the minimum value of the terminal voltage required for self-excitation. To maintain a constant terminal voltage, a method for determining the frequency, terminal capacitance, and exciting reactance is also described.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1998.10a
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• pp.241-253
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• 1998

By the rapid expansion of containerization and intermodel transportation in international shipping since the 1970's, the larger containerships have emerged and concentrated their calls at a limitted number of ports. Moreover, large-scale container terminals have been built to accommodate the ever-larger containerships, and the mordernization of terminal facilities and many developments in information technology etc. have been brought out. Thus, unlimited competition has been imposed on every terminal with neighbouring ports in Japan, Singapore, Hongkong and Taiwan etc. The purpose of this study is invested to suggest how the container terminal operators cope with unlimited competition between local or foreign terminals. The results are suggested as follows : First, transshipment cargoes, which the added value is high, is to be induced. Second, the function of storage is given on On-Dock Yard. Third. Berth Pool Operation System is introduced, especially in Gamman Container Terminal and Kwangyang Container Terminal. Fourth, the cargo handling charges is decided by terminal operator.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.6
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• pp.153-163
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• 2011

This research describe improved algorithm that is able to decide terminal criterion of Evolutionary Structural Optimization (ESO), reducing load of calculation to search load path of concrete beam, and apply to agricultural facilities. The ESO method is that make to discrete structure, structural analyze each element stress through FEM. And repeat generation with next material condition to become for most suitable composing. Individual element introduces concept of zero stiffness, but zero stiffness decisions are gone to direction of exclusion. In this stduy, improve algorithm to be convergence by 'Rule of Alive or Die' in arrival because is most suitable. Also, existing terminal criterion lack consistency because that used depend on experience of researcher. This research procedure is fellowed. First, all modulus of elasticity assume a half of elasticity modulus of material, Second, structural analysis by FEM, Third, apply to the remove ratio and restoration ratio for the 'rule of alive or die'. Forth, reconstruct the element and material conditions. And repeat the first to forth process. The terminal time of evolutional procedure is the all elastic modulus of element changed to blank value or elasticity modulus value of original. Therefore, in this study, consist the algorithm for programming, and apply to the agricultural facilities with concrete.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1393-1406
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• 2018

In this study, three parameters (Pressure ($X_1$), Airflow rate ($X_2$), Operation time ($X_3$)) were experimentally designed and the predicted model and optimal conditions were established by using the terminal rise velocity of the microbubbles as the response value. The polynomial regression analysis showed that the optimum value for the terminal rise velocity at the Pressure ($X_1$) of 4.5 bar, Airflow rate ($X_2$) of 3.3 L/min and Operation time ($X_3$) of 2.2 min was 5.14 cm/min ($85.7{\mu}m/sec$). Also, the highest microbubble diameter size distribution in the range of 2 to $5{\mu}m$ and 25 to $50{\mu}m$ was confirmed by using a laser particle counting apparatus.

• Journal of the Korean Operations Research and Management Science Society
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• v.33 no.2
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• pp.75-86
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• 2008

A remarshalling is one of the operational strategies considered importantly at a port container terminal for the fast ship operations and heighten efficiency of slacking yard. The remarshalling rearranges the containers scattered at a yard block in order to reduce the transfer time and the rehandling time of container handling equipments. This Paper deals with the rearrangement problem, which decides to where containers are transported considering time value of each operations. We propose the mixed integer programming model minimizing the weighted total operation cost. This model is a NP-hard problem. Therefore we develope the heuristic algorithm for rearrangement problem to real world adaption. We compare the heuristic algorithm with the optimum model in terms of the computation times and total cost. For the sensitivity analysis of configuration of storage and cost weight, a variety of scenarios are experimented.

• Journal of Navigation and Port Research
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• v.28 no.1
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• pp.69-74
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• 2004

Container Freight Station(CFS), which would be located inside terminal or outside, plays the role of consolidating less than container load(LCL) cargo gathered from multi shippers and deconsolidating full container load cargo into individual consignment. When CFS is allocated inside terminal it muses several problem such as traffic gam around terminal, high social and logistics cost and deterioration of terminal condition. This study, therefore, tries to evaluate the location of CFS, inside and outside of terminal, with respect to the social and logistics costs.

• Journal of Navigation and Port Research
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• v.34 no.9
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• pp.719-726
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• 2010

As the competition among the container terminals in Korea has become increasingly fierce, every terminal is striving to increase its investments constantly and lower its operational costs in order to maintain the competitive edge and provide satisfactory services to terminal users. The unreasoning behavior, however, has induced that substantial waste and inefficiency exists in container terminal production. Therefore, it is of great importance for the terminal to know whether it has fully used its existing infrastructures and that output has been maximized given the input. From this perspective, data envelopment analysis (DEA) provides a more appropriate benchmark. This study applies three models of DEA to acquire a variety of analytical results about the operational efficiency to the Korean container terminals. According to efficiency value analysis, this study first finds the reason of inefficiency. It is followed by identification of the potential areas of improvement for inefficient terminals by applying slack variable method and giving the projection results. Finally, return to scale approach is used to assess whether each terminal is in a state of increasing, decreasing, or constant return to scale. The results of this study can provide terminal managers with insight into resource allocation and optimization of the operating performance.

• Proceedings of the Korean System Dynamics Society
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• 2006.11a
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• pp.93-105
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• 2006

A container terminal should concentrate on efficient terminal operation in the long view and analyze an effect through introduction of hi-technology, automated equipments and intelligent information system, when they want to improve their reliability and competitive power in intense global competition. To do this, first this study finds out factors which affect competitive power of a container terminal, and relation between them. And then we used System Dynamics method to analyze an effect according to a value fluctuation of the factors in the long term.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1559-1566
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• 2015

The brushless DC motor (BLDCM) has many advantages. As a result, it is widely used in electric vehicle (EV) drive systems. To improve the reliability of the motor control system, a position sensorless control strategy based on a sliding mode observer (SMO) is proposed. The global fast terminal sliding mode observer (GFTSMO) is proposed to enhance the control performance of the SMO control system. The advantages of the linear sliding mode and the nonsingular terminal sliding mode (NTSM) are combined in the control strategy. The convergence speed of the system state is enhanced. The motor commutation point is obtained with the observation of the back EMF, and the instantaneous torque value of the motor is calculated. Therefore, the position sensorless control of the BLDCM is realized. Experimental results show that the proposed control strategy can improve the convergence speed, dynamic characteristics and robustness of the system.

• Journal of applied mathematics & informatics
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• v.29 no.3_4
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• pp.937-948
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• 2011

The method of Asymptotic Inner Boundary Condition for Singularly Perturbed Two-Point Boundary value Problems is presented. By using a terminal point, the original second order problem is divided in to two problems namely inner region and outer region problems. The original problem is replaced by an asymptotically equivalent first order problem and using the stretching transformation, the asymptotic inner condition in implicit form at the terminal point is determined from the reduced equation of the original second order problem. The modified inner region problem, using the transformation with implicit boundary conditions is solved and produces a condition for the outer region problem. We used Chawla's fourth order method to solve both the inner and outer region problems. The proposed method is iterative on the terminal point. Some numerical examples are solved to demonstrate the applicability of the method.