• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.1-5
• /
• 2007

An electric motor unit (EMU) is manufactured from a large number of components and parts which are made of extensive raw materials. In emits much environmental load throughout its entire life cycle, having both complicated and elaborated system and long period of life time. Therefore, it is necessary to investigate the methodologies and tools to analyze the environmental performance of EMUs throughout their life cycle. RACE (Rail Assessment for Clean Environment) developed in this study is the software that can analyze the environmental impacts and eco-efficiency of EMUs, which are new concepts proposed for sustainable development. It has database for main components as well as principal materials contained in EMUs. Manufacturers and operators can use it to assess the life-cycle environmental impacts of EMU and support their decision making. RACE can also be used as a tool for environmental communication between manufacturers and operators.

• Proceedings of the IEEK Conference
• /
• 2001.06a
• /
• pp.253-256
• /
• 2001

This paper describes a high speed MAC(Media Access Control) function chip for IEEE 802.11 MAC layer protocol. The MAC chip has control registers and interrupt scheme for interface with CPU and deals with transmission/reception of data as a unit of frame. The developed MAC chip is composed of protocol control block, transmission block, and reception block which supports the BCF function in IEEE 802.11 specification. The test suite which is adopted in order to verify operation of the MAC chip includes various functions, such as RTS-CTS frame exchange procedure, correct IFS(Inter Frame Space)timing, access procedure, random backoff procedure, retransmission procedure, fragmented frame transmission/reception procedure, duplicate reception frame detection, NAV(Network Allocation Vector), reception error processing, broadcast frame transmission/reception procedure, beacon frame transmission/reception procedure, and transmission/reception FIEO operation. By using this technique, it is possible to reduce the load of CPU and firmware size in high speed wireless LAN system.

• Proceedings of the KIEE Conference
• /
• 2008.10c
• /
• pp.211-212
• /
• 2008

There are many new technologies for EMU to secure the facilities' safety/validity and maintenance/economical efficiency and technologic competitiveness. For example, now the EMU is using the blending brake technology with electric brake and pneumatic brake and carrying the various performances such as jerk limitation, variable load and blending brake to stop the motor car safely and efficiently. Now we start applying such new methods, taking the whole inspection prior to the installation by analyzing systems' requirements and introducing various system engineering design tools. In this paper, we suggest how to reduce the errors by prelieminarly inspection for the brake facilities using the tools and inspect the needs to analyze the brake facilities' performances.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.16 no.4
• /
• pp.15-21
• /
• 2002

This paper presents parallel operation of ZVT(Zero Voltage Transition) FUll Bridge Converter with Dynamic Current Shared Inductor. In the conventional method, CT(Current Transformer) have been used tn share the load current equally with converters. In this system, at parallel operation of ZVT Full Bridge Converter, dynamic current shared inductor divides the same current of unit converter and ZVT circuit aids to high efficiency. Superiority of the characteristics is verified through the experiment with a 2[㎾], 50[㎑] prototype converter.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.17 no.3
• /
• pp.47-57
• /
• 1992

The purpose of this paper is to improve the operation performance of unit-load Automated Guided Vehicles (AGV's) used as a carrier and mobile workstation in a flow-shop type flexible manufacturing system. An algorithm is developed to determine the optimal job sequence which minimizes the vehicle idle time on the line and the production makespan by the use of the entering interval and travel time between workcenters. An entering times of AGV's and the minimum number of AGV's required are calculated by optimal job sequence. When the numbe rof AGV's is limited, enterling times of AGV's are adjusted to maximize the efficient use of vehicles. A numerical example is given to illustrate the application of the algorithm.

• Management Science and Financial Engineering
• /
• v.17 no.2
• /
• pp.23-37
• /
• 2011

In this paper, we address a layout design problem for determining an optimal 4-class-based dedicated linear storage layout in a class of unit load storage systems. Assuming that space requirement for a class is the sum of the maximum inventory levels of products assigned to the class, and that one-way travel time is a linear function of storage index, we formulate a 4-class-based dedicated linear storage problem PTL[4] and provide an exact splitting algorithm with $O(n{\lceil}logn{\rceil})$. Our algorithms could be applied to more than a 4-class-based dedicated storage layout problem with slight modification in order to reduce computational execution time.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.06a
• /
• pp.293-298
• /
• 2005

The following is final report for governor upgrade for PWR NPP safety related EDG Kori NPP No.2 Unit. The upgraded system includes more beneficial function like as "Slow start with starting ramp", "Generator load sensing & control capability" and "Emergency ramp during slow start". This paper show functional operation of slow start regime according to NRC regulatory guide which guide regulation to NPP safety related environment.

• Proceedings of the KIEE Conference
• /
• 1990.07a
• /
• pp.421-424
• /
• 1990

In this parer, the parameter for control variable is consist of value that take measured the input line current and input total power-factor, and the compensation susceptance is calculated by its parameters. The compensator can reduce the reactive power generation by the system to zero, thus the input total power-factor is kept on sustaining the unit power- factor.

• Proceedings of the KIEE Conference
• /
• 1999.11b
• /
• pp.147-149
• /
• 1999

This paper deals with the determination of generator/exciter model parameters for a Cheju Hanlim steam turbine unit. Using the recorded data from the generator characteristic tests, the model parameters have been derived and verified by comparing the simulation results and recorded data. In addition to it, the closed-loop performance of voltage control on no-load condition has been assessed in the frequency domain by taking advantage of derived generator/exciter model parameters.

• Korean Management Science Review
• /
• v.11 no.1
• /
• pp.23-37
• /
• 1994

This paper discusses the methodology for the operational performance of unit-load automated guided vehicles(AGVs) in a flow-shop-type flexible machining and assembly systems (FM/AS). Throughout the paper, AGVs are working as a carrier and mobile workstation. For a double-loop FM/AS, in which one loop is dedicated to machining and the other to assembly, three AGV operating strategies are proposed. Considering the entering interval and travel time of AGVs between workcenters, the strategies are developed to determine the best job sequence which minimizes the makespan and vehicle idle time. Entering times of AGVs and the required minimum number of AGVs are obtained on the basis of the best job sequence. When the number of AGVs are limited, entering times of AGVs are adjusted to maximize the utilization of AGVs.