• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.163-170
• /
• 2008

Auxiliary port which had been known to be used to reduce the expansion loss of a refrigeration system was applied to a R134a reciprocating compressor in a household refrigerator cycle with an intention of improving the compressor performance. Effects of the auxiliary port on the compressor performance was investigated by a computer simulation program. When a simple hole was made on the side wall of the cylinder as an auxiliary port and surrounding gas inside the compressor shell was assumed to be drawn into the cylinder through the hole, maximum COP improvement of 1.66% was obtained. With auxiliary port equipped with a plate type of check valve, maximum COP was raised to be 1.99%. COP improvement was more distinctive with decreasing the discharge pressure; COP improvement was 5% with discharge pressure of 7 bar.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.10
• /
• pp.637-644
• /
• 2008

Auxiliary port which had been known to be used to reduce the expansion loss of a refrigeration system was applied to a R134a reciprocating compressor in a household refrigerator cycle with an intention of improving the compressor performance. Effects of the auxiliary port on the compressor performance was investigated by a computer simulation program. When a simple hole was made on the side wall of the cylinder as an auxiliary port and surrounding gas inside the compressor shell was assumed to be drawn into the cylinder through the hole, maximum COP improvement of 1.66% was obtained. With auxiliary port equipped with a plate type of check valve, maximum COP was raised to be 1.99%. COP improvement was more distinctive with decreasing the discharge pressure; COP improvement was 5% with discharge pressure of 7 bar.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.5 no.2
• /
• pp.175-182
• /
• 2001

Five reinforced concrete frames were constructed and tested to study the structural performance of retrofitting effect reinforced concrete frame during and load revesals simultaneously. All specimens were modeling in one-third scale size. Experimental research was carried out to develop and evaluate the hysteretic behavior of reinforced concrete frame designed by high performance techniques, using carbon fiber plate, ALC panel, steel plate system with or without stiffener. Experimental programs wore carried to evaluate the structural performance of such test specimens, such as the hysteretic behavior, the maximum horizontal strength, crack propagation, and ductility etc. Specimens(RFCP, RFAR, RFSR, RFSR-S), designed by the improvement of earthquake-resistant performance, were attained more load-carrying capacity, energy dissipation capacity, and stable hysteretic behavior.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.34 no.4
• /
• pp.42-48
• /
• 2011

This paper proposes performance measurement method of quality small-group activity in business. This paper collects and analyzes quality circle activities data respect to tangible and intangible effect in national quality circles competitions festival. This paper proposes QPI (quality-circle performance index) based on Balanced Scorecard for quality small-group activity in quality improvement area. QPI is to measure the performance of quality improvement activities in the business firms. QPI is able to use widely in industries to provide a performance measure of quality small-group activity. In this paper, we propose the application method of QPl.

• The Journal of Information Systems
• /
• v.31 no.1
• /
• pp.239-269
• /
• 2022

Purpose This paper attempts to identify items for improving the usage of PLM(Product Lifecycle Management) systems and suggests ways to prioritize improvement items on the basis of importance. It also tries to find out differences in the importance of improvement items due to the company size, the industry, the job, or the PLM solution. Design/methodology/approach Through a survey from participants to a PLM System Conference, data were collected from a sample of 181 users who had the previous experience in using a PLM system. In order to figure out the differences in the importance among user groups, the F-test with the Scheffe test as a post-hoc analysis was used in case of equal variances and the Welch test with the Dunnett T3 test was used in case of unequal variances. Findings This study sorted out 25 improvement ideas according to their importance assessed by the PLM system users. The top five ideas are improving data consistency, error minimization, fast system response time, enhancing user recognition, and business process improvement. The support group puts higher importance than the general user group in data consistency, fast system response time, enhancing user recognition, business process improvement, dedicated team for data consistency, continuous support from management, hardware performance upgrade, output linkage to other systems, and shortening problem solving duration. The largest company group attaches significantly higher weights than the smallest company group to data consistency, error minimization, fast system response time, business process improvement, dedicated team for data consistency, security with proper access management, output linkage to other systems, and better user interface.

• Proceedings of the KIEE Conference
• /
• 2004.11c
• /
• pp.62-65
• /
• 2004

An optimal robust controller design method for gun driving system is discussed in this paper. The parameters of the gun driving controller are tuned by using the LQR characteristics for the performance and robustness. Tuning method that optimize velocity error gives a significant improvement over the existing PID tuning methods. It is shown that the tuning result of real gun driving system which is regarded as rigidness model or stiffness model satisfy performance and robustness.

• 제어로봇시스템학회:학술대회논문집
• /
• 1989.10a
• /
• pp.1091-1096
• /
• 1989

All mechanical systems have saturation nonlinearity in actuators or in final control elements. When controllers have integral action, reset windup can cause instability as well as make the system performance unsatisfactory. In this study, an intelligent limiter which needs no tuning of parameters is tested with the PDF controller used for control of a second order plant. This paper presents analysis of the stability of the system using the describing function method and the Nyquist stability theorem. The improvement of the system performance by the limiter is illustrated by computer simulations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.571-576
• /
• 2001

Hydroforming, the new production technology, has been used to manufacture many parts of vehicle in the recent auto industry. When Hydroforming is applied, it is possible to make parts simplification and flexible alteration of section shape in many advantages such as weight reduction, number of parts reduction or performance improvement. This research into shape optimization which reduces number of parts and weight maintaining performance was achieved. In this paper, the COWL CROSS BAA and MT'g BAKT parts of A car STEERING support SYSTEM was introduced by using Hydroforming.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.10a
• /
• pp.766-769
• /
• 2009

In this paper we propose a new turbo coded T-DMB system that replaces the existing RS code, convolutional interleaver and RCPC code by a turbo code without altering the puncturing procedure and puncturing vectors defined in the standard T-DMB system for compatibility. Simulation results show that the new turbo coded system yields considerable performance gain after just 2 iterations.

• Journal of the Korea Society of Computer and Information
• /
• v.23 no.12
• /
• pp.115-122
• /
• 2018

As the proportion of software in weapon systems increases, the impact of software on the overall system is growing. As a result, software quality management becomes important, and related regulations and work manuals for quality assurance activities at each stage in the R & D process are becoming more sophisticated. However, due to the characteristics of the weapon system software that is developed as a customized form for the purpose of a specific mission, there are limits to specifying and definitizing the detailed requirements (upper and lower level) according to various operational concepts during the development process. Due to this, software modification (patch change, shape change due to upgrade, etc.) occurs on account of many defects and performance improvement in the mass production and operation stage after the development is completed. In this study, we analyze the characteristics of these weapon system softwares and propose quality improvement methods based on ISO / IEC / IEEE 29119 test method.