• Journal of the Korean Wood Science and Technology
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• 제46권4호
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• pp.362-367
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• 2018

This study estimates the sound absorption capability of rice straw particle mats by two methods: the transfer function method and the reverberation room method. In the reverberation method, the central frequency was set to the one-third octave band in the 100-5000 Hz range; in the transfer function method, the frequency range was 500-6400 Hz. Both methods yielded similar noise reduction coefficients of the rice straw mats. The noise reduction coefficient was approximately 0.8, indicating a high sound-absorption property of the mats. Therefore, rice straw matting is a suitable candidate material for sound-barrier walls against highway noise.

• 대한환경공학회지
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• 제39권12호
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• pp.679-684
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• 2017

고속열차의 설계 및 운행기술이 발전하면서 고속철도의 운행속도가 빠르게 증속되고 있다. 반면 증속 시 발생하는 소음으로 인해 고속철도 연변의 주거지역 등에서는 많은 소음문제가 발생하고 있으며, 고속철도 소음에 대한 민원도 지속적인 증가추세에 있다. 향후 고속철도가 원활히 설계속도대로 운행되기 위해서는 고속철도의 방사소음특성에 적합한 소음예측기술 및 저감기술이 개발되어야 한다. 이와 같은 요구에 부합하기 위해, 400 km/h 고속철도 인프라 연구가 수년에 걸쳐 진행되었다. 이 연구를 통해 신뢰성을 갖는 고속철도 소음예측평가 기술이 개발되었고, 현재 소음저감기술의 단점을 극복하기 위한 핵심방음장치가 개발되었다. 본 연구의 궁극적인 목적은 고속철도 환경소음을 줄이기 위해 개발된 선로 변 벽체 상단에 설치되는 상단장치의 소음성능평가 및 풍압안전성 검증에 관한 것이다.

• 한국구조물진단유지관리공학회 논문집
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• 제24권3호
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• pp.9-17
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• 2020

이 연구의 목적은 프리캐스트 콘크리트 벽체와 H-pile로 구성된 벽체구조의 횡하중저항 성능을 평가하는 것이다. 이러한 형태의 구조는 옹벽 및 방음벽 기초 구조물로 사용된다. 실제 크기의 목업시험체를 설계하였으며, 실험체를 제작하였다. 대상 구조체의 설계횡하중은 54.6kN이다. 실제 현장에서 6.5m의 파일과 유사한 변형 프로파일을 갖는 실험체의 파일의 길이를 이론적으로 결정하였으며, 1.5m로 제작하였다. 실험중 벽체의 횡방향 변위가 파일의 변형률을 모니터링 하였으며, 균열의 발생을 육안 조사하였다. 실험으로부터 평가된 하중 및 변형 능력을 설계능력과 비교하였다. 실험결과는 설계하중을 저항하는데 충분한 성능을 보유하고 있음을 나타냈다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.521-524
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• 2005

To protect a satellite and electronic equipment from the acoustic loads generated by rocket propulsion system, many launch vehicle use acoustic blanket. Most high frequency region of the acoustic loads is reduced by nose fairing skins and acoustic barrier, but low frequency region is not. In order to control low frequency acoustic mode, we designed away resonator panel which was made of composite materials. This paper shows the absorption coefficient measurement result of resonator and SPL(Sound Pressure Level) reduction by using resonators in a rectangular cavity for experiment. Proper arrangement of acoustic resonators at each mode reduce effectively SPL around the satellite through changing boundary condition.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.64-66
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• 2004

Several techniques have been adopted in motor design of interior permanent magnet (IPM) type brushless DC (BLDC) motor to minimize cogging torque. IPM type motor has better ability in the centralization of flux than surface-mounted permanent magnet (SPM) type BLDC motor. So, the structure of IPM type BLDC motor has high saliency ratios that produce additional torque. However, this structure has a significant cogging torque that generates both vibration and noise. This paper describes new technique of the flux barriers design for reduction of cogging torque of IPM type BLDC motor. To reduce the cogging torque, flux barriers are applied in the rotor. Changing the number of barrier, the cogging torque is analyzed by finite clement method(FEM).

• 한국주거학회:학술대회논문집
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• 한국주거학회 2009년도 추계학술발표대회 논문집
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• pp.213-216
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• 2009

The purpose of this study is analyzing temporal flow about 20 detailed performance items in the "Housing Performance Grading Indication System". This study try to figure out situations according grade in detailed performance item and to analyze change item about 112 cases(2 cases in 2006, 15 cases in 2007, 46 cases in 2008, 49 cases in 2009), from January 9, 2006 which system is undertaken, to October, 2009. This system consists of 5 main performance section, 14 performance categories and 20 detailed performance items. 5 main performance parts are Noise and Acoustics(Light-weight impact sound control, heavy-weight impact sound control, sound control of toilet, sound control of party wall), Long-life(flexibility, remodeling & maintenance, durability), Landscape & Indoor Environment(landscape, formaldehyde control & ventilation, daylighting, thermal environment), Welfare & Barrier-free(playground and community center, welfare space, barrier-free design), Fire Safety(fire safety, safe place, fire-resisting quality). Total efficiency about housing can understand systematically of 20 perfomance items though this research.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2008년 추계학술발표대회 논문집
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• pp.479-482
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• 2008

The purpose of this study is a proposal about the flexibility of the performance category to revitalize the "Housing Performance Grading Indication System". This system consists of 5 main performance parts, 14 performance categories and 20 detailed performance lists. 5 main performance parts are Noise and Acoustics(Light-weight impact sound control, heavy-weight impact sound control, sound control of toilet, sound control of party wall), Long-life(flexibility, remodeling & maintenance, durability), Landscape & Indoor Environment(landscape, formaldehyde control& ventilation, daylighting, thermal environment), Welfare & Barrier-free(playground and community center, welfare space, barrier-free design), Fire Safety(fire safety, safe place, fire-resisting quality). The flexibility of the performance category is conformed to Long-life housing related grading and can realize the Long-life housing in response to resident needs about the space rearrangement. Now, The flexibility of the performance category is limited to the evaluation of the private space, that is, the Skeleton evaluation. This study would suggest alternatives to improve uppermost limits through analyzing 60 examples from January 9th 2009 to October 30th 2008. The flexibility of the performance category is possible to estimate not only the Skeleton evaluation but also the Infill evaluation in response to social changes.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.606-611
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• 2000

It has been noted that the low frequency absorption coefficient of a porous sample placed in a standing wave tube is affected by the nature of the sample's edge constraint. The edge constraint has the effect of stiffening the solid phase of the sample, which itself can be strongly coupled to the material's fluid phase, and hence the incident sound field, by viscous means at low frequencies. In recent work it has also been shown that such a circumferential constraint causes the low frequency transmission loss of a layer of fibrous material to approach a finite low frequency limit that is proportional to the flow resistance of the layer and which is substantially higher than that of an unconstrained sample of the same material. However, it was also found that the benefit of the circumferential edge constraint was reduced in a transitional frequency range by a shearing resonance of the sample. Here it will be shown that the effect of that resonance can be mitigated or eliminated by adding additional axial and radial constraints running through the sample. It will also be shown that the constraint effect can be modeled closely by using a finite element procedure based on the Biot poroelastic theory. Implications for low frequency barrier design are also discussed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1020-1025
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• 2004

This research reviews the characteristics of earth pressure incurred by GRS-RW mainly used in the railroad design in order to resist large lateral load caused by train and additional load induced by facilities such as noise barrier fences, electric poles, etc. The results of test shows the existence of arching effect that horizontal earth pressure increases in the backfill while earth pressure applying to the wall reduced under GRS-RW system. In both cases, unreinforced wall and GRS-RW system, the coefficient of earth pressure (K) is about 0.4 at the rest. However, after lateral displacement occurs, the earth pressure nearly reduce down to zero under GRS-RW system while the earth pressure decreases up to 0.12 in case of unreinforced retaining wall.

• 한국BIM학회 논문집
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• 제9권4호
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• pp.51-61
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• 2019

In the general manufacturing sector, prototyping used to reduce the risks that can arise with new conceptual products. However, in AEC area, it does not mass-produce a building, so the prototype itself becomes a building. Therefore, it is challenging to have prototyping of the same scale as the real thing, and the prototyping process in architecture is very inefficient. The prototyping process in the design stage typically assumes making a scaled model, partial model, or digital model. However, it is difficult for these models to correspond to the actual building and the environment of time and space such as scale, material, environment, load, physical properties and deformation, corrosion, etc., unlike the actual building. When using the digital twin concept in the prototyping process, it is possible to measure performance from the design stage to the operation stage. The digital twin was found by a method for monitoring based on physical twins and real-time linkage in the operation stage. Therefore, if the digital twin concept is applied at the design stage, it is possible to predict performance using not only current performance but also history information using real-time information. In order to apply the digital twin concept to the prototyping design process, we analyze the theoretical considerations and the prototyping design process of the digital twin, analyze the cases and research results where the prototyping design was applied, Provide an applied prototyping design process. The proposed process is tested through a pilot project and analyzed for potential use.