• 대한기계학회논문집B
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• 제37권12호
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• pp.1167-1173
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• 2013

본 연구에서는 천연가스 유량 측정에서 2차 표준으로 사용되는 소닉노즐 뱅크 -12개 노즐 패키지로 구성-의 임계유동함수 계산 시간을 1초 이하로 단축하고자 하였다. 이를 위해 AGA 8-dc 상태방정식을 적용한 헬름홀츠 자유에너지를 유도하고 이로부터 적분 항이 없는 열역학 상태량 식을 도출하여 CFF 계산에 적용하였다. 그 결과 CFF 계산 시간이 기존 6.7초/12개에서 0.6초/12개로 크게 감소하는 것을 확인할 수 있었고 이 계산 시간은 가스 성분 수와 거의 무관함도 알 수 있었다. 또한 본 계산 결과의 정확도를 확인하기 위해 기존 CFF 국제비교연구의 결과와 비교한 결과 차이가 없음도 확인하였다.

• 대한기계학회논문집A
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• 제30권2호
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• pp.202-209
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• 2006

As the economic power is improved and the customer's demand is hard to please, the noise and vibration is the most important yardstick that can determine the quality of the product. Especially, as the airconditioner's demand increase suddenly, the product of quality and the noise is becoming a decisive factor of determining whether purchase the product or not. Therefore, every manufactory is investing a lot of money and research to cut down the unpleasantness induced from noise and vibration. And they are emphasizing their product's difference by advertising a silence very actively. With these reason, the demand of a silent indoor air-conditioner is the essential research filed when the product is develop(:d. In this study, the noise and vibration is visualized in the space and frequency domain by using experimental methods such as operational deflection shape (ODS), modal testing and sound intensity. Also the location of noise source and its characteristic is analyzed in an acoustical point of view to reduce the structure borne noise that come from the fan motor, and the pertinent control method is suggested. Furthermore, the most suitable shape of the motor bracket is suggested by applying FEM and DOE (Design of experiments) in the noise and vibration point a view.

• 소성∙가공
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• 제23권2호
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• pp.116-121
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• 2014

Low pressure die casting and flow forming have been successfully used to produce sound road wheels from magnesium alloy AM80. In the current study, high speed compression testing was initially conducted to simulate the flow forming of a Mg wheel. Subsequently the flow forming was simulated with "Forge$^{TM}$", an FEM software package. On the basis of flow forming simulations, the flow forming of the Mg wheel was performed under different conditions. For the flow forming experiments, the preform castings were made by low pressure die casting from AM80, a commercial magnesium alloy. In flow forming of the magnesium preform wheel, the flow forming of the Mg wheel was successfully accomplished when the feed rate was less than half that for the forming of an aluminum road wheel. The reduction in feed rate was 52%. Finally, a comparison with the flow forming simulations was made.

• 대한영양사협회학술지
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• 제8권1호
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• pp.42-51
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• 2002

Questionnaire survey was performed in order to set an adequate meal table for athletes taking their food preferences into consideration. The survey was conducted against 32 athletes of a professional soccer team. Statistical data analysis was performed utilizing SAS package program. The results of this study can be summarized as follows; 18.8% of the answerers were found out to consider their autotrophic nutritional status as above average, 75.0% considered theirs as up to the average and 6.2%, below average. Among answers to the question what they consider as the most critical factor in their staying healthy; sound sleep won the most votes followed by enough rest, tranquillity and balanced eating habit. Yet, 68.8% replied their meal sizes were not settled. And 46.9% thought nutritive supplement helpful and 96.9% of the answerers said a dietitian is required as their health manager. 62.5% of them preferred Korean cuisine. Chigye and Chongol were the most preferred menus(55.6%) and Namul (28.1%), Muchim(26.3%) and Cheok.cheon(23.9%) enjoyed relatively low preference.

• 가정간호학회지
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• 제27권1호
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• pp.82-91
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• 2020

Purpose: This study aimed to explore the factors influencing attitudes toward withdrawal of life-sustaining treatment (WLST) in adolescents. Methods: This study used a descriptive research design. A structured questionnaire was administered to 185 adolescents. Data were analyzed based on t-tests, analysis of variance, Pearson's correlation coefficient, and multiple regression using the IBM SPSS 20.0. Statistical package. Results: There was a negative correlation between attitudes toward WLST and respect for life (r=-.188, p=.010). Knowing about life-sustaining treatment (β=-0.30, p<.001), experience of WLST education (β=0.21, p=.003), experience of respect for life education (β=-0.16, p=.021), and experience of death (family or acquaintance) (β=-0.13, p=.039) explained 16.7% (F=8.39, p<.001) of the variance in attitudes toward WLST. The respect for life did not affect attitudes toward WLST (β=-0.07, p=.347). Conclusion: The study findings suggest that WLST in adolescents is different from that of adults. Further research is needed to develop strategies for sound and positive attitudes toward WLST in adolescents.

• 한국조경학회지
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• 제35권2호통권121호
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• pp.64-70
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• 2007

The main purposes of this paper are to determine the major factors influencing visual preference in soundproofing barriers in urban places and to provide the essential information needed in the design process of soundproofing harriers. This paper consists of two phases. The first phase presents photos of the seven types of soundproofing barriers generally seen around the Daejeon area, which were taken from three places for a photo montage. The evaluation of 21 different soundproofing barriers was conducted by college students. The second phase of this paper depicts the analysis process. Firstly, the visual preferences as found from the collected data were evaluated by five semantic degrees. The evaluated data were processed by descriptive test, a correlation test and ANOVA test methods using an SPSS statistical package. 1. Currently, visual preference in soundproofing barriers is low in urban places. Therefore, it is necessary to design visually pleasing soundproofing barriers to improve the visual qualify of urban areas. 2. Soundproofing barriers of mixed wood and acrylic scored the highest among selections while those with aluminium steel scored the lowest. 3. Environmental friendly and transparent conditions should be met to allow soundproofing barriers to be visually pleasing.

• 한국소음진동공학회논문집
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• 제17권5호
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• pp.448-455
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• 2007

As Decentralized Generation(DG) becomes more reliable and economically feasible, it is expected that a higher application of DG units would be interconnected to the existing grids. This new market penetration of DG technologies is linked to a large number of factors like technologies costs and performances, interconnection issues, safety, market regulations, environmental issues or grid connection constrains. This paper describes the procedures and results for the mechanical, electrical, and environmental tests of MGT on actual grid-connection under Korean regulations. As one of the achievements, the simulation model of MGT was developed, so that it will be able to analyze or propose new distributed generation system using MGT. The field test was conducted in order to respond to a wide variety of needs for noise reduction and utilization and its performance was evaluated in consideration of its operational problems. The MGT is successfully supplying electricity to Korean grids with satisfying various regulations. The suggested strategy and experience for the evaluation of the distributed generation will be used for the introduction of other distributed generation technologies into the grid in the future.

• 한국음향학회지
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• 제19권4호
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• pp.107-114
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• 2000

기존의 Push-Pull 트랜스듀서보다 간단한 구조를 가지며 출력을 한층 더 높이기 위해서 실린더 중앙에 구동부를 둔 새로운 구조의 Push-Pull 트랜스듀서를 설계하고자 한다. 유한 요소 상용 패키지인 ANSYS를 이용하여 트랜스듀서 모델을 구성한 후, 각종 구조 변수들, 즉, 길이, 반경, Endcap Edge 형상등의 변화에 대한 음압의 변화경향을 조사하여 최대 음압을 구현하기 위한 최적 길이, 반경, Endcap Edge 형상을 설정하였다. 기존 트랜스듀서 보다 구조적으로 더 간단하면서도 더 큰 음압을 구현할 수 있는 새로운 구조의 고출력 트랜스듀서를 개발하였고, 그 성능을 기존 트랜스듀서의 성능과 비교 평가함으로써 개발된 트랜스듀서의 우수성을 입증하였다.

• 한국유체기계학회 논문집
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• 제11권1호
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• pp.26-32
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• 2008

The safe operation of high pressure pipe line systems is of significant importance. Leaks due to faulty operation from the pipelines can lead to considerable product losses and to exposure of community to dangerous gases. There are several leak detection methods of pipeline network which have recently been suggested. The negative pressure wave detection technology, which has advantages of short time detection availability, accurate leaking location estimate capability and cost effective, is concentrated in this study. Theoretical analysis of the flow characteristics for leaking through a hole on the pipe wall has been performed by using Fluent 6.3, commercial CFD package. The results of 3-dimensional analysis near leaking hole confirm the occurrence of negative pressure wave, and the results of 2-dimensional analysis verify the characteristics of propagation of the wave which travels with speed equal to the speed of sound in the pipeline contents. Characteristics of leakage and pressure in a pipe with a hole have been analyzed for the various pipe and hole sizes.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.277-282
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• 2006

Road traffic noise is not produced by any one factor rather occurs as a composition of various factors. Its occurrence is made by running engine noise, tire frictional, and exhaust noise etc. The quality of the noise depends on the size of the vehicles, rotation and engine speed, vehicle load, package state of the road and incline etc. The occurrence of noise level of heavy trucks appears louder than smaller vehicles and the noise levels produced differs according to speed and load etc between similar size vehicles. Other factors such as traffic density, average speed, mixing rate of heavy vehicles, and the distance between vehicles also generate road traffic noise. In this paper we examine 2, 4, and 6-lane roads in Jeonju. Consequently, this study examined the means used to measure road traffic noise. It was found that when there is a large traffic density and the average velocity is below 70 km/hr, the noise level could receive a relative proper value by the current measuring means. But in the case of night-time, it was found that the current measuring method is inapposite.