• 대한기계학회논문집A
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• 제24권9호
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• pp.2302-2312
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• 2000

An active control of the transmission of noise through an aircraft fuselage is investigated numerically. A cylinder-cavity system was used as a model for this study. The fuselage is modeled as a fi nite, thin shel cylinder with constant thickness. The sound field generated by an exterior monopole source is transmitted into the cavity through the cylinder. Point force actuators on the cylinder are driven by error sensor that is placed in 3D cavity. Modal coupling theory is used to formulate the numerical models and describe the system behavior. Minimization of the acoustic potential energy in the fuselage is carried out as a performance index. Continuous parameter genetic algorithm is used to search the optimal actuator position and both results are compared.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.162-165
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• 1998

The non-thermal pasteurization of foods using High Voltage High Current Pulsed Electric Fields (HVHC-PEF) is a promising technology and a sound complement or replacement to traditional thermal pasteurization. The conventional thermal method also inactivates bacteria and other microorganisms harmful to humans, but degrades natural color, flavor, texture and nutrients. At this point, a nonthermal pasteurization technique, HVPEF is thought to be a new processing technique which is able to produce a good quality foods nutritional as well as sensuous. In this paper, the system for HVHC-PEF pasteurization is presented. It use square wave pulse instead of exponential ones. So, power rating of system is reduced considerably. Design considerations for 20kV 500A class equipment are analyzed and experimental results are discussed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.938-941
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• 2004

Sound generation and radiation from the duct-rotor system are calculated numerically. The wake geometries of a two-bladed rotor are calculated by using a time-marching fiee-wake method without a non-physical model of the far wake. Acoustic free field due to a rotating rotor is obtained by Lowson's equation. Using Kirchhoff source, rotating sources are modeled as stationary ones and can be inserted in the thin body boundary element method. The Kirchhoff source is validated through calculation of acoustic pressure due to a rotating point force. The thin body boundary element method (thin body BEM) is validated through calculation of acoustic radiation of ducted dipole. Using Kirchhoff source and thin body BEM, acoustic radiation of a ducted rotating source is calculated. Acoustic shielding is observed by inserting a duct and shows different phenomena at each major frequency. Acoustic radiation of a real duct-rotor system is also calculated using this method and the ducted acoustic field is significantly different from rotor only.

• Tribology and Lubricants
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• 제27권5호
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• pp.269-274
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• 2011

The purpose of this paper is to study and analyze the improvement method for the failure examples including the vehicle brake system in actual field. It was verified that the indicator plate of pad wear scratched the brake disk because of wearing after displacement of non- identification parts pad. The caliper of other vehicle was installed with brake system verified the phenomenon produced groove in center point because of one side wear when the pad was not fully contacted with the rub disk by other action surface pressure and pad action condition. It verified that the crack phenomenon fatigue was produced by brake thermal deformation because of decreasing the thickness by grinding to modify the non-uniformed wear of brake disk. It verified that the friction sound was produced by the friction phenomenon because of non-uniformed contact of lining and an alien substance with inner of the drum and lining braking by crack phenomenon with brake drum surface.

• 한국소음진동공학회논문집
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• 제21권11호
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• pp.1029-1035
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• 2011

Pressure pulsation of exciting sources that generally occurs on the piping system connected to the discharge of BFP(boiler feed water pump) in power plants causes wave reflection, wave interference, resonance, standing wave and so on. But if the operating speed of the pump is changed, the state of the noise and vibration can be done because characteristics of the exciting source are changed. This paper is to investigate the cause of the noise and vibration occurring on the piping system when the operating speed of BFP is down in accordance with lowering of the power generation. It is approached to two points of view ; Firstly, it is examined whether the pulsation source impacts on the shell mode vibration that vibrates radially across the cross-section of the pipe. But it doesn't affect the shell mode as much as the resonance occurs. Secondly, to find the relation between the pulsation source and the acoustic mode of the piping system, analysis for the piping system by indirect BEM(boundary element method) is carried out. Therefore it is investigated that the mechanism of the noise and vibration relates with acoustic mode of the piping system.

• 한국가정과교육학회지
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• 제11권2호
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• pp.13-26
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• 1999

The goals of this research are for producing and optimizing the CD-ROM, effective and practical Teaching-Learning method. It consists of Wearing Korean Traditional Costume for the First Grade of Middle School Students in Home Economics Teaching. This research’s summarization is following. First, the multi-media material. CD-ROM making use of Powerpoint. Wearing Korean Traditional Costume, is produced to help the students learn the difficult contents in terms of video and audio. Second, it is introduced the model of Open Education for increasing the efficiency of class. Third, it is developed to proceed the class with the CD-ROM and small group study of place activity. Fourth, it helps students concentrate on the class with proper sound effect whenever the slide films are changed. And it helps to link the web sites related to Korean Traditional Costume. Finally, another kinds of suggestions are following. The effective verification of this software that is tested and applied at the field for a given period will be necessary. And, it is necessary to upgrade for the CD-ROM and the supplementary teaching materials in Korean Traditional Costume education.

• Journal of Plant Biotechnology
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• 제35권1호
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• pp.5-12
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• 2008

The transgenic technologies and their product (living modified organisms) have been developed and commercialized enough to get much attention in terms of their potentials to solve the current global difficulties such as shortage of food and energy. Furthermore, they are expected to make a big role in improving human health levels and creating bio-economy as innovative tools to pursue environmentally sound economic development. However, for the technologies and products to be developed and used in such a way that they continuously give a good impact to human society, first and foremost safety issues surrounding them should be dealt with. Every stage from in-house R&D, pilot field application to on the shelves should be managed to ensure safety following them because many consumers tend to have fear before they get the right or needed information on the modern biotechnology. In this sense, managing research facilities and LMOs for R&D from the point of safety is very crucial in that they are in the early stage of technology or product development. This paper especially deals with those to be complied with by researchers according to the Act on transboundary movement of LMOs, etc, entered into the effect from Jan. 1 2008.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1191-1196
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• 2009

The T-s chart of air displays graphically the thermophysical properties, so it is very conveniently used in various thermal systems. In previous study, the software analyzing 31 kinds of values in water system and 32 kinds of values in air-conditioning system were developed. In this study, the software drawing 13 kinds of quantity of state on air properties as ideal gas and analyzing 25 kinds of values in any air system was developed. The 13 kinds of quantity of state on air properties are temperature, pressure, specific volume, specific internal energy, specific enthalpy, specific entropy, specific exergy, exergy ratio, density, isobaric specific heat, isochoric specific heat, ratio of specific heat, and velocity of sound, and the 25 kinds of values including 13 kinds are mass flow rate, volume flow rate, internal energy flow rate, enthalpy flow rate, entropy flow rate, exergy flow rate, heat flow rate, power output, power efficiency, reversible work, lost work, and relative humidity. The developed software can draw any range of chart and analysis any state or process on air system. Also, this supports various document-editing functions such as power point. We wish to this chart is a help to design, analysis, and education in air system field.

• KIEAE Journal
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• 제7권6호
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• pp.3-8
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• 2007

Recently, because of the continuous rise of international oil price, energy saving is strongly demanding. So, Ecological technics of architecture such as use of natural energy have been actively explored in the field of building. In the method of utilizing natural energy, the key point is to saving energy effectively as not lowering the comfort of indoor environment, various systems investigated. Many papers about double skin facade system have been reported, it is announced broadly that the system is very effective in improvement of natural ventilation and indoor thermal environment, and also protecting outdoor sound. The shaft box facade is a special form of box window construction. It consists of a system of box windows with continuous vertical shafts that extend over a number of stories to create a stack effect. The facade layout consists of an alternation of box windows and vertical shaft segments. This research investigated the natural ventilation performance of shaft box type balcony which conform the shaft box type double skin to the exiting balcony construction. First, analyzed various types of exiting apartments, proto-type was decided. By using virtual environment Program, modeling the proto-type, compared the contribution of air temperature and the effect of outdoor air cooling. by this research, we confirmed that shaft box type balcony had many possibility for improvement of indoor environment.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.33-42
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• 2005

Studies on community annoyance caused by transportation noise exposure were carried out in fifty-one areas around Gimpo and Gimhae international airports, Gyungbu and Honam railway lines and east and riverside-northen motorway to accumulate social survey data and to assess the relationship between each transportation noise level and degree of annoyance in Korea. The measurements of transpotation noise were carried out using portable precision sound level meters (B&K type 2238 and LD 812) except in aircraft noise. Aircraft noise levels were measured automatically by airport noise monitoring system, B&K type 35n Social surveys were carried out to people living around noise measurement points. Questionnaires were only aggregated by face-to-face interviews using various questions concerned with demographic factors, degree of noise annoyance, interference with daily activities and health-related symptoms. The questions of noise annoyance were answered on an 11-point numerical scale. The respondents, from 18 to 70 years of age, were randomly selected and completed the questionnaire for themselves. The total number of respondents for the questionnaires was 1,839. The results showed that community annoyance of railway noise in Korea is similar to that in Japan, but is more severe than that in European countries.