• Proceedings of the KSR Conference
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• 2009.05b
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• pp.209-214
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• 2009

In this research, an external noise distribution of a HST has been analyzed by using a ray tracing techniques. An aero-dynamic noise generated from a bogie has been considered as a major noise source. Then a distribution of the noise on the outside of the vehicle is calculated using a ray noise technique. The models simulated are two different acoustic fields: an open field and a tunnel. In order to evaluate the noise effects, an exterior structure has been modified by using a different length of skirts. Various application schemes of reducing an environmental noise level will be expected for a HST based on this research.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.447-453
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• 2009

The interior noise of the High Speed Train(HST) is analyzed by applying the statistical energy analysis (SEA) method. The interior of each vehicle is divided lengthwise into nine cavities. Since the rolling noise and aerodynamics noise are expected to be dominant noise sources, they are treated as the noise sources in the model. To further simplify the model, curtains and seats are excluded. The simulation runs involving one-car, three-car and five-car trains are conducted. The maximum predicted noise level is 98.4dB. The results also show that the predicted noise levels are within 0.23% of each other. The results imply that it is not necessary to estimate the interior noise of the train by constructing multiple-car train models. The noise estimate based on just one-car train can be optimal with respect to the computational effort and modeling time.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1441-1447
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• 2008

This research studies the effects of community noise around railway, noise from the inside/outside noise of the High-Speed EMU. First study part of this year is research of the noise source. The modeling methodology for prediction of noise level including the frequency property, velocity dependence, sound pressure of noise source is investigate. Second part is research on the sound transmission loss. An exclusive program which could analyze the sound transmission loss of the floor, the sides(mirror), insulator in High-Speed EMU has to be developed. Third part is research on the train inside/outside and Prediction for community Noise. In order to predict the noise when the High-Speed EMU is traveling at the outside and along tunnels, the result of the research can be derived by evaluating the effect of the noise on the upper/middle parts of the carriage and on the railroad way round about with using the program.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.953-954
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• 2009

이제 기업에서는 정보화 없이는 하루도 운영이 안 될 정도로 정보화의 역할과 중요도가 커지고, IT를 사용하는 이용자는 확대되고 있다. 그러나 실제 IT 서비스를 이용하는 수혜자 입장에서의 만족도는 높지 않은 것으로 나와 있다. IT 서비스산업의 시스템 운영부문에서 고객만족도를 위한 서비스 품질변수 결정에 대한 연구를 통해 고객만족도를 높일 수 있는 방법을 연구하였다

• Proceedings of the Korea Information Processing Society Conference
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• 2020.11a
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• pp.1118-1121
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• 2020

전체 해양 사고 원인 중 선박 운항 부주의가 34%로 사고 발생 원인 중 대다수를 차지한다. 해당 문제를 해결하기 위해서는 선박 운항자를 대상으로 효과적인 운항 교육 및 실시간 관제 시스템을 제공해 사고를 방지하는 것이 중요하다. 따라서 울산항만을 현실적으로 반영한 가상현실 시물레이션 및 5g 수상드론을 이용한 운항 교육 시스템과 모든 선박들이 사용가능한 실시간 관제 시스템을 연구하고 이를 울산 항만에 제공한다.

• Journal of Wind Energy
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• v.5 no.1
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• pp.50-55
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• 2014

Surface Permanent-Magnetic-Synchronous-Generator (SPMSG) discussed in the present study has operational characteristics such as high rotational speed over 1,000 rpm and centrifugal force of 12 kN·m for each magnet. Structure-development analysis for the minimization of rotor-core weights and the maximization of thermal emission is performed by applying the aluminum-laminated cap which combines the advantages of IPM and SPM in order to overcome the difficulty that attaching the magnet to rotor-core only with an adhesive. In this study, the simulations in terms of structure and electromagnetic were performed with the variable parameters such as shape and thickness of laminated-cap and division method of magnet. As a result, condition for minimized centrifugal force with minimum loss is derived.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.4
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• pp.65-71
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• 2003

A new type of ultrasonic spray nozzle was fabricated employing a piezoelectric device. The spray nozzle was designed to disperse chemicals in a water treatment mixing tank. The piezoelectric properties in ultrasonic spray nozzles were optimized to improve the dispersion of chemicals. The piezoelectrics were packaged in an aluminum case with silicone resin for the aqueous solution proof packaging. Chemicals were dispersed with high efficiency and the chemicals consumption was reduced by the ultrasonic fine particle spraying. The concentration of Escherichia coli in mixing tank was decreased remarkably using ultrasonic spray nozzle dispersion compared to the conventional methods.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.37-38
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• 2011

본 논문에서는 RT(Real Time)기반의 IPMSM(Interior Permanent Magnet Synchronous Motor) 설계 및 해석, 평가 플랫폼을 개발하고자한다. GUI(Graphical User Interface)로 제작 된 플랫폼 실행창에서 설계변수의 수치적 입력을 통해 설계 자동화를 구현하며, 수치해석프로그램 FEMM과 연동함으로써 전동의 전자계 해석 및 제어정수의 추출을 수행한다. 아울러 추출된 제어정수를 이용, Simulink의 실시간 시뮬레이션을 통해 IPMSM의 제어를 수행하여 통합적 설계 해석 평가를 도출한다.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.6
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• pp.723-734
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• 2010

With a belief of high water quality production and less chemical usage, membrane technology including Microfiltration (MF), Ultrafiltration (UF), and Nanofiltration(NF) is being employed more and more in drinking water treatment process. However, due to higher energy consumption of UF and NF, MF is normally used for drinking water treatment especially in a plant of large scale. In this investigation, performance ofsand filtration and membrane filtration was compared regarding removal of various water quality parameters, such as TOC, DOC, KMnO4 consumption, THMFP, and HAAFP. Two lines of pilot plant have been operated, one of which line is a traditional advanced water treatment process which includes sedimentation, sand filtration, ozonation, and activated carbon, and the other line is an alternative treatment process which includes sedimentation with inclined plate, MF membrane, ozonation, and activated carbon. For the first about 4months of period, MF filtration showed similar or little bit higher performance than sand filtration. However, after about 4month later, sand filtration showed much higher performance in removing all parameters monitored in the investigation. It was found that sand filtration is a better option than MF filtration as far as microbial community is fully activated in sand filter bed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.312-316
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• 2002

Recently, mixers are being widely used in the water purification plant in order to increase the filtration efficiency. It has been found that a severe vibration was being felt on a upper structure of a mixer facility during steady state operation. The cause of the excessive vibration of the structure to which the mixer's shaft is supported has been evaluated through modal analysis on the shaft and vibration measurements during operation. The fundamental natural frequency of the mixer's shaft is found to be around 1.8 Hz and the main vibratory frequency around 30 Hz. It has been tuned out that the main vibratory frequency, 30 Hz is coincident with the fundamental holding frequency of the upper structure, and that the acceleration signal of the upper structure and the displacement signal of the mixer's shaft showed highly coherent to each other. Accordingly, it reveals that the main cause of the excessive vibration is due not to the mixer's vibration but to the natural frequency of the upper structure excited by flow turbulence.