• Journal of Digital Contents Society
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• v.4 no.2
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• pp.181-189
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• 2003

The requirement of distributed multimedia applications is the need for sophisticated QoS(quality of service) management. In terms of distributed multimedia systems, the most important catagories for quality of service are a timeless, volume, and reliability In this paper, we discuss a method for increasing reliability through fault tolerance. We describe the design and implementation of the ECA running on distributed multimedia environment. ECA is a system is able to classify automatically a software error based on distributed multimedia. This papaer explains a performance analysis of an error classification system running on distributed multimedia environment using the rule-based DEVS modeling and simulation techniques. In DEVS, a system has a time base, inputs, states, outputs, and functions.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.701-705
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• 2006

This paper dealt with a component test of train control and management system(TMS) developed for korean tilting train express(TTX). This system that is established on TTX monitors and controls action of various devices by running of the train. Also, to performance estimation of the TMS, it is essential to verify a composition and function of TMS. Therefore, this study reviewed standards related on a component test of the TMS and confirmed test items, test conditions and evaluation basis on a Component Test. Running Test of TTX can verify performance of TMS and communications with other devices and secure reliability of TMS.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.295-301
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• 1997

본 연구의 목적은 수도권 전동차량의 주행성능을 평가하는 방법으로 진동성능을 비교검토하기 위하여 실차측정하고 분석한 것이다. 전동차량의 제작년도별로 측정대상차량을 샘플링하여 다양한 조건에서 진동을 측정하고 실측데이타를 시간영역의 통계적 방법으로 분석한 결과 제작년도에 따른 영향도 약간 나타났으며 전동차량의 2차 현가장치의 종류에 따른 영향을 발견할 수 있었다. 또한 측정선로구간의 특성에 따른 영향도 비교적 잘 나타나고 있음을 알 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.275-282
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• 2018

Mountain trams are an environmental-friendly transportation system that run wirelessly on an embedded track constructed on previous mountain roads, and can run despite the frozen road. On the other hand, there is some difficulty on sharp and steep tracks. In this study, after possible technical problems were defined in mountain trams running on a sharp and steep track, the design solutions for the interface structure of bogie and carbody were proposed. In addition, a prototype was made and its performance was tested to verify the solutions. Because the difference in the distance of the inner and outer rails on a sharp curve is severe enough to interrupt running, independent rotating wheels with different angular speeds were developed and applied. To prevent derailment due to the large attack angle and lateral force caused by the previous vehicle of 2bogie-and-1carbody on the sharp curve, a vehicle with 1bogie-and-1carbody was designed and applied. A prototype vehicle of 1bogie-and-1carbody with independent rotating wheels was made to improve the performance during the test running on a small track. A coupler was designed to absorb the large rotations of 3 degrees-of-freedom between the carbodies of a mountain tram running on the steep curved track. After a small scale prototype was made, the performance was verified by a function test.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.6
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• pp.321-327
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• 2015

This study presents an HFC152a refrigerant air conditioner as an alternative to HFC134a, which is currently used in mobile air conditioning systems. Cool-down performance tests of an HFC152a air conditioning system were conducted and compared to a baseline HFC134a air conditioner. The experimental set-up consisted of a belt-driven compressor, a sub-cooled type condenser, an evaporator, and a block-type thermal expansion valve (TXV). A drop-in test was carried out on the mobile air conditioning system under various vehicle running speeds in a climate-controlled wind tunnel (CWT). Additionally, to optimize the HFC152a air conditioning system, the effects of the TXVs on the performance were studied. The results show that compared to the HFC134a air conditioning system, the refrigerant charge quantity was reduced by approximately 20%, the discharge pressure was reduced by about 350~430 kPa, and the air discharge temperature at vehicle running conditions was $0.5{\sim}1.5^{\circ}C$ lower. In addition, good compressor durability was expected due to the lower compression ratio.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.9
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• pp.759-764
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• 2014

Lateral force of wheel is important parameter when we evaluate the safety of a railway vehicle on curved track. The lateral force of wheel is influenced by the steering performance of wheelsets. Generally, in passive type vehicles, the steering performance of wheelsets is influenced by the parameters like primary spring stiffness, wheel base, conicity of the wheel profile, etc. But, the steering performance of passive type vehicle has its limit. To overcome the limit of the steering performance of passive type vehicle, active steering technology is being developed. In this paper, we analyze the lateral force of wheel and the safety of the railway vehicle on curved track by adopting the active steering technology. As results of dynamic analysis for vehicle model equipped with active steering system, the lateral force of wheel is reduced and the safety is improved remarkably.

• The Journal of Korea Robotics Society
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• v.14 no.4
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• pp.270-277
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• 2019

Inspired by small insects, which perform rapid and stable locomotion based on body softness and tripod gait, various milli-scale six-legged crawling robots were developed to move rapidly in harsh environment. In particular, cockroach's leg compliance was resembled to enhance the locomotion performance of the crawling robots. In this paper, we investigated the effects of changing leg compliance for the locomotion performance of the small light weight legged crawling robot under various payload condition. First, we developed robust milli-scale six-leg crawling robot which actuated by one motor and fabricated in SCM method with light and soft material. Using this robot platform, we measured the running velocity of the robot depending on the leg stiffness and payload. In result, there was optimal range of the leg stiffness enhancing the locomotion ability at each payload condition in the experiment. It suggests that the performance of the crawling robot can be improved by adjusting stiffness of the legs in given payload condition.

• The KIPS Transactions:PartA
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• v.9A no.4
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• pp.563-572
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• 2002

A performance monitor is indispensable to trace and evaluate performance of a program under distributed processing environment. A performance monitor il classified as off-line and on-line according to its output method. An off-line performance monitor analyzes its performance after a program terminates, and an on-line performance monitor analyzes its one while a program runs. Therefore, the on-line function is essential to analyzing and debugging the program fast. JaNeC, distributed processing environment that is implemented in Java, contains an off-line performance monitor for this. However, this performance monitor may not analyze the program running on JaNeC efficiently. Consequently, this paper explains that an on-line performance monitor is designed and implemented for fast analysis and debugging of the program running on JaNeC. This on-line performance monitor is designed to minimize effects on a program to analyze, and provides various forms of graphic output, to analyze the program effectively. In addition, even after a program terminates, it provides interface with the off-line performance monitor, to analyze again.

• Journal of Korean Association for Spatial Structures
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• v.20 no.4
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• pp.21-25
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• 2020

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.93-97
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• 2011

This paper presents the performance and test results of propulsion system which is met the requirements of urban MAGLEV. The design of propulsion system should be considered the effect of attractive force by the magnetic levitation and train running resistance. In this paper, the tractive and braking thrust are calculated and the train performance is simulated for the service track. Finally the test results of complete car are shown to verify the performance.