• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.5
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• pp.377-384
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• 2002

For economic evaluation of cooling plant equipments, it is necessary to simplify energy Prediction method, which should includes efficiency corrected by part-load ratio. This study proposed simplified method with regression equations of time-average partial loads and refrigerator capacity. DOE-2 Program was used to carry out a parametric study of twelve design variables. Five input variables were considered to be significant and were used in the regression equations. To test accuracy of simplified method, calculated results were compared with DOE-2 simulated results. Test result showes a good agreement with the simulation result with an error of 5.9∼7.6%. It is expected that this method can be used as an easy prediction tool for comparing energy use of different cooling plants during the early design stage.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.3
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• pp.174-178
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• 2015

This paper describes a signal processing technique for identifying signals from defects by using an electromagnetic-ultrasonic guided waves method based on a magnetostrictive sensor that generates a torsional mode (T(0, 1)). Because this technique is based on the digital filtering, the filtered signals provide information on the relationship between the cutoff frequency of band-pass filter and the characteristic of defect signals in heat exchange tubes. To verify the performance of the technique, artificial defects with various thickness reduction ration and shape were machined in titanium tubes, and digital filtering results are reported. The results show that digital filtering provides information to the identify shape of defects and the contact condition between the tube and support ring. Therefore, the proposed technique has good potential as a tool for evaluating the integrity of heat exchange tubes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1444-1449
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• 2000

This environmental influence of the noise produced by a number of air-conditioner out-door units in a multi-unit housing is predicted and evaluated. The method based on Ray tracing theory and mirror image source theory is utilized. Each ventilation window in a machine room is considered as a sound source which contributes to the overall noise level of the surrounding environment. The adopted method has been found a very efficient tool to assess the environmental noise impact.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.996-1001
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• 2000

The sound transmission from the machine room where air-conditioner outdoor unit is located into the adjacent room is predicted and evaluated. The software package for statistical energy analysis(SEA) is utilized to determine the transmission losses of multi-layerd panels. To determine the noise level in the machine room, ray tracing method is adopted. The various sound transmission paths have been effectively identified and evaluated by the SEA tool.

• Journal of Welding and Joining
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• v.23 no.3
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• pp.40-46
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• 2005

Air gun has been one of the good tools to press two sheet metals. However, it is not easy to control the acting force precisely. A Servo-gun is a good tool to control the acting force on the workpiece comparing with the air gun. Servo-gun has a higher tensile shear strength and lower indentation depth as well as smaller spatter. Dynamic resistance was obtained according to the acting force and welding current. As the acting force was changed during welding, the welding quality was increased.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.326-333
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• 2004

This paper presents the structural characteristics analysis of a high-speed horizontal machining center with spindle speed of 50, 000rpm and feedrate of 120m/min. The spindle system is designed based on the built-in motor, angular contact ceramic ball bearings, oil-air lubrication and oil-jacket cooling method. The X-axis and Y-axis feeding systems are composed of the linear motor and linear motion guides, and the Z-axis feeding system is composed of the servo-motor, ball screw and linear motion guide. The structural analysis model of the high-speed horizontal machining center is constructed by the finite element method, and the validity of structural design is estimated based on the structural deformation of the high-speed horizontal machining center and spindle nose caused by the gravity and inertia forces.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.561-566
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• 2000

A screw driver is essentially used in assembling machine parts and electronic products such as the printed circuit board with a housing. As the parts to be assembled becomes small and precise, the higher precision of the controling screw driver torque is required. However, because the operator controls the fastening torque by his experience, it must be inexact. Thus the screw driver which can exactly control the fastening torque by a bellows is designed and developed in the study. The bellows is expanded by the inner air pressure and contracted and by the spring operation. The bellows driver is composed of the entrance solenoid valve, the exit solenoid valve and the pressure sensor. The pressure sensor senses the bellows pressure. When the pressure sensor output reaches the setting value, it operates the exit solenoid valve not to deliver further torque by letting the air of the bellows out. Through a series of experiments, the performance is studied and verified.

• Journal of the military operations research society of Korea
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• v.24 no.2
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• pp.1-16
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• 1998

Aircraft combat survivability(ACS) can be defined here as the probability of an aircraft to accomplish a given mission and not to be killed by enemy threats. The purpose of this thesis is to obtain analytically the combat survivability of the military aircraft according to the enemy and operation environment. Five factors under which a mission is being carried out are considered in this study. These factors are types and performance of enemy threats, aircraft susceptibility, aircraft vulnerability, ECM(electronic counter measures) capability, and pilot's capability. The model constructed in this study would be a useful tool to analyze ACS based on analytical method. It is also able to provide a better input data for wargaming simulation and present a criterion on determining optimal sorties for aircraft's air-to-ground mission.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06b
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• pp.104-105
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• 2012

최근 항공용 전자 시스템은 IMA (Integrated Modular Avionics) 방식으로 개발되고 있고 여기에는 실시간 운영체제의 표준인 ARINC 653이 적용되고 있다. ARINC 653은 시간적 공간적 파티셔닝을 제공함으로써 항공용 시스템의 안전성을 보장하며, OS 커널과 응용 소프트웨어 사이에 표준 API를 제공함으로써 두 파트가 서로 독립적으로 개발될 수 있게 한다. 이러한 방식은 시스템의 이식성을 높일 수 있는데, 이를 보장하는 핵심 기법이 ARINC 653 설정이다. 본 논문에서는 산업현장에서 ARINC 653 설정을 쉽게 적용하여 응용 소프트웨어를 개발할 수 있는 도구를 소개한다.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.3
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• pp.44-51
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• 2008

The performance design and analysis of an electric motor for vehicles is very complicated due to the variety of parameters. This paper presents the design of the BLDC motor for electric air compressor in high voltage(42V) system and compares with the characteristics of IPM, SPM type BLDC motor. Futher, optimal design for the electric motor has been carried out using Equivalent Magnetic Circuit and FEM Modelling. By analyzing the design results, it is found that design parameters for BLDC motor provided an useful tool for vehicles motor design.