• Journal of the Korea Safety Management & Science
• /
• v.8 no.3
• /
• pp.103-114
• /
• 2006

A cross docking operation involves multiple trucks (known as inbound trucks) that deliver items from suppliers to a distribution center and multiple trucks (known as outbound trucks) that ship items from the distribution center to customers. Based on customer demands, an inbound truck may have its items transferred to multiple outbound trucks. Similarly, an outbound truck can receive its consignments from multiple inbound trucks. A unique characteristic of a cross docking system is the absence or prohibition of long term storage of items at the distribution center. Items delivered to the distribution center from suppliers are shipped to customers as soon as possible without being placed in storage in the distribution center. The objective of this paper is to develop the optimal operational strategy for finding the best truck docking sequence for both inbound and outbound trucks in order to minimize total operation time where a temporary storage area is not available in a cross docking system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.18 no.5
• /
• pp.174-182
• /
• 2004

Consideration for parallel operation in a high power system has been increased due to the advantages of parallel operation like as high productivity, simplicity of design, and redundancy of power. Based on the small signal model of DC-DC Converter, the simple and exact power stage model of parallel operation system is derived and the parallel operation system using current balance method for the uniform current distribution among the parallel operation system is proposed. Using Simulation programs, which consists of nonidentical Converter modules and changes the position of master and slave automatically, the current distribution error is kept within the limit in the parallel operation system. To verify the high performance of the proposed Converter system for parallel operation, the parallel operation test, which has 2 Converter modules of 1 kW, is accomplished. Also, the simulation result is good agreement with the experiment result in the transient and starting characteristics.

• Journal of the Korean Geographical Society
• /
• v.36 no.3
• /
• pp.258-277
• /
• 2001

Agricultural Co-operation chain stores were highly the utility of distribution rationalization for commercial distribution by informatisation and by multi-polarizied of large physical distribution center of Inventory intensive type consisted of intensive physical distribution. and transportation of commodities from physical distribution center have act by outsourcing. Therefore, the methods of distribution of commodities of life and agricultural products are distinguished from route distribution and regular time collective distribution. the method of distribution is formated the distribution field b\ulcorner characteristic of commodity. On the other hand, spatial characteristics by sales activities of commodities was clarified by types of stole commodity according to level of paddy agriculture development and level of service industrial employment. But manufactured foodstuffs and miscellaneous goods. that is commodities of life clarified the fact selling that is not influenced by regional type.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.4
• /
• pp.474-481
• /
• 2013

It is anticipated that AC distribution system can be replaced by DC distribution system in the near future because of the operation of various distributed source or microgrid system. However DC distribution system replacing 22.9kV AC distribution line is not sufficiently studied still. This paper describes lightning overvoltage analysis among many research fields should be studied to realize DC overhead distribution systems. DC distribution system is modeled using EMTP and overvoltage is analyzed according to interval of arrestor location, earth interval of overhead grounding wire and grounding resistance. It is evaluated that analysis results can be effectively used to design of future DC distribution system.

• Journal of Advanced Marine Engineering and Technology
• /
• v.24 no.3
• /
• pp.106-112
• /
• 2000

Since the oil crisis, we have been concerned about the energy saving techniques of electric generating systems. As a part of the effort to save energy, automatic electric load sharing device was developed. Usually, ship's electric generating system consists of two or three sets of generator. And, electric generating system is operated as single or parallel operation mode according to the demanded electric power. Therefore, it is important to investigate generators operating mode for the supply of required electric power in the ship in order to decrease the operating cost. So, this paper suggests the method to solve the optimal electric load distribution problem by dynamic programming. And, this thesis indicates that the proposed method is superior to the lagrange multiplier's method in obtaining optimal load distribution solution in the ship's electric generating system.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.2
• /
• pp.164-171
• /
• 2008

This paper proposes the planning method for placement of capacitors in a distribution system. The main objectives in the planning for capacitor allocation are the reduction of installation costs and electric power loss. In the proposed method, the life time of each device is considered in calculating installation costs, and the optimal operation status of devices is found by genetic algorithm. Then, the optimal numbers and locations are determined based on the optimal operation status. Simulation results in the 69-bus distribution system show that the proposed method performs better than conventional methods.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.10
• /
• pp.1832-1837
• /
• 2011

The fault current has increased due to the large power demand in power distribution system and network distribution system. To protect the power system effectively from the increased fault current, the superconducting fault current limiter (SFCL) has been notified. However, the conventional SFCL has some problems such as cost, operation, recovery, loss. To solve some problems, the hybrid superconducting fault current limiter using the fast switch was proposed. However, hybrid SFCL also has a problem that is protection coordination in power distribution system with hybrid SFCL. In this paper, the fault current limiting characteristics of hybrid SFCL with first half cycle non-limiting operation according to the fault angle, the resistance of superconducting element, and the magnitude of Current Limit Resistor (CLR) which are the components of hybrid SFCL were analyzed through the experiments.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.7
• /
• pp.1135-1140
• /
• 2008

Superconducting fault current limiters (SFCL) have been progressing due to the development of superconducting technology. The resistor type SFCL is one of the promising current limiting devices in power system for its effective operation. For proper application and operation of a SFCL, the prior investigation of fundamental characteristics and its effects to the distribution systems are needed. The most important current limiting behavior of a SFCL is dominated by quenching and recovery characteristics. In this paper, the resistive type SFCL was developed by using EMTP/ATPDraw and MODELS language. The operating characteristics and current limiting behaviors of the SFCL in distribution systems have been simulated and investigated.

• Proceedings of the KIEE Conference
• /
• 1997.07c
• /
• pp.761-763
• /
• 1997

As the power system network is enlarged and complicated gradually, the automation of power system network is essential to enhance the reliability and performance of the operation of power system. Distribution restoration is a major part of the automation. This paper proposes a new distribution restoration system to restore healthy blackout regions by the hierarchical cooperation with the substation automation systems. In proposed system, the range of restoration is extended to substations and the performance as well as the switching efficiency of restoration system is enhanced.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.9
• /
• pp.581-589
• /
• 2008

The pulverized coal combustion behavior in the utility boiler is very complex since so many physical and chemical processes happen in it, simultaneously. The mixing of pulverized coal with combustion air plays an important role in achieving the efficient combustion and stable boiler operation. The distribution of combustion air supplied to the furnace through the windbox damper system has not been clearly known since the individual measurements of air flow for each air nozzle were not possible, yet. The present study describes the CFD modelling of windbox damper system and aims to obtain the air flow rates and pressure loss coefficients across the present five damper systems, respectively. The one dimensional flow network model has been also established to get air flow distributions across the windbox damper, and applied to the actual plant operation condition. Compared with the designed air flow distribution, the modelled one gives a reasonable agreement. For the actual plant operation, the predicted air flow distribution at each air nozzle is differed with the designed data and strongly affected by the individual opening angle.