• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.201-204
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• 1998

강당, 회의실, 강의실 등과 같은 닫혀진 공간에서 포착된 소리의 질은 반향음과 간섭 잡음 등에 의해 영향을 받는다. 마이크로폰에 수신되는 신호는 직접전달파와 벽면에 의한 반사파들이 더해지므로 해서 실제 발생음을 명확히 얻기가 어렵다. 수신측 마이크로폰에서 반사음의 영향을 제거하면 실제 발생음에 가까운 양질의 소리를 얻을 수 있을 것이다. 잡음과 반향음의 영향이 큰 음향 공간에서 고음질의 소리를 얻기 위한 방법으로 마이크로폰 배열의 병렬 신호 처리 기법이 있다. 본 연구에서 제시된 마이크로폰 배열의 병렬 신호처리 기법은 공간적 음량 선택성을 제공하기 위해 각 마이크로폰 센서들의 matched filter 처리와 병렬 처리 기법을 결합한다. 이 기법은 다중경로 왜곡(반향)과 간섭 잡음을 제거하는 수단을 제공한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.6
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• pp.1238-1244
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• 2011

This paper presents the matching method of reflectors for localization of laser navigation. The laser navigation is a device that measures distance and angle of reflector. The conventional major matching using the laser navigation is method that moves position of measured reflectors to position of installed reflectors and than rotate moved reflectors. However, it is difficult to use the industry because it has high computational complexity and high errors. To solve those problem, The proposed matching is method that create position of measured reflectors to assume that the position of installed reflectors is position of AGV and than rotate the position of installed reflectors. For experiment, we used AGV which was designed by ourselves, and compared positioning accuracy when AGV moves according to varying steering angle and driving speed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.403-408
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• 2019

In general, the caisson having the perforated wall is used to for the purpose of reducing the wave reflection and wave overtopping. In this study, the hydraulic characteristics (reflection coefficient) of the perforated wall caisson chamber filled with aggregates (rocks) were investigated with hydraulic model tests. When the perforated wall chambers were filled with aggregates, the reflection coefficients would increase. However, it was confirmed that the rock filling method into the perforated wall chamber could secure the stability of the structures and satisfy the hydraulic characteristics at a certain level.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.5
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• pp.235-241
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• 2018

The internal pressure is a critical parameter for designing a pressure vessel. The static pressure that a pressure vessel must withstand is usually determined according to the various codes and standards with simple formula or numerical simulations considering the geometric parameters such as diameter and thickness of a vessel. However, there is no specific codes or technical standards we can use practically for designing of pressure vessels which have to endure the detonation pressure. Detonation pressure is a kind of dynamic pressure which causes an impulsive pressure on the vessel wall in a extremely short time duration. In addition, it is known that the magnitude of reflected pressure at the vessel wall due to the explosion can be over twice the incident pressure. Therefore, if we only consider the reflected pressure, the design of the pressure vessel can be too conservative from the economical point of view. In this study, we suggest a practical method to evaluate the magnitude of maximum allowable pressure that the pressure vessel can withstand against the detonation inside a vessel. As an example to validate the proposed method, we consider the pressure vessel containing hydrogen gas.

• Journal of Digital Contents Society
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• v.8 no.4
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• pp.459-465
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• 2007

In this paper, we implemented a ray-tracing simulator with a ray-launching technique and generated the propagation path of each ray in a multiple-wall indoor environment. In this simulator, we adopted two dimension ray-tracing techniques considering the reflection and penetration were dominant propagation factor in the indoor channel. From the result, we verified that this ray-tracing simulator shows the similar path pattern and delay distribution with the experiment results of the previous research. Especially, impulse responses of the ray were corresponding to reference result in non-line of sight of multiple-wall indoor environment. Furthermore, we confirmed that channel profiles having respectively different departure angle 1 degree to 7 degree were similar between them.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1994.10a
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• pp.191-200
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• 1994

사각형 유체저장탱크의 바닥에 놓여져 있는 사각형 블럭의 크기 및 위치가 자유수면의 유동진동수와 모드형상에 미치는 영향에 대하여 선형파이론을 적용하여 검토하였다. 유체의 영역을 3부분으로 나누고 각 영역에서의 속도포텐셜을 입사파와 블럭으로 인해 발생되는 반사파 및 전달파의 항으로써 표현하였다. 그리고 블럭에 의한 파의 반사율과 전달율은 유체영역의 경계에서 속도포텐셜과 유체입자의 속도가 연속인 조건을 사용하여 구하였다. 연구결과 블럭의 높이와 폭은 자유수면의 고유진동수에 크게 영향을 미치며 높이와 위치는 모드형상에 주로 영향을 준다. 블럭이 높고 폭이 넓을수록 고유 진동수는 감소하며 블럭이 높고 탱크의 벽면으로 이동할수록 모드형상은 크게 변한다.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.19-26
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• 2009

This study is performed by method for the influx of natural light in underground space. to solve the several negative underground issues make the covered courtyard and high reflected wall toward the adjacent space. for illuminance level test of sunken garden space, the adjacent space size is $15M{\times}9M{\times}12M$ sunken Garden with space to install the ceiling on the size of the companion light performance analysis, and seasonal changes derived by the light of changes in performance. In addition, increase the distance of the wall and the adjacent space and estimate the average at true time P.M12. The resulting data indicate that the road was an average lux DESKTOP RADIANCE of the modeling and analysis was conducted.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.1
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• pp.25-32
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• 2008

This paper presents the reflection and transmission measurements conducted at the 60GHz suitable to provide a high speed wide band service. Mean received power and standard deviation are calculated and used to compare the characteristics of radio wave propagation to the various obstacles between transmitting and receiving antennas at the frequency. The results show that the transmitted signal strength by the steel door and copper plate are about 40dB lower than in free space, those by the rubber plate, glass and styroform are about 3dB lower than in free space. Also, the re(looted signal strengths at the 60 degree grazing angle show that in case by the partition is about 23dB lower, by the surface of a wall is about 6dB lower than by the copper plate. The presented results can be used for the design of 60 GHz picocell communication network that the reflected and transmitted waves affect to the service area.

• The Journal of the Acoustical Society of Korea
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• v.23 no.4
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• pp.268-273
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• 2004

A method of reflection-transmission type ultrasonic inverse scattering image was presented using linearly arrayed transducers in inner surface of half-cylinder. In this method, to reduce the number of data, the mirror effect using a reflector behind object and pulse wave with finite frequency band, To verify the proposed method, a computer simulation was performed for organic phantom specimen, As the results. it was verified that the reconstructed image was satisfactory even when the limitation view angle was limited to around 30 deg.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.5
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• pp.371-383
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• 2011

It is important to secure illumination for the driver's safety because the tunnel is a space for changing brightness quickly, and lighting fixtures of the tunnel have consumed a lot of electric lighting energy for operating in both the daytime and at night. This study aims to evaluate daylighting performance of Mirror Reflector System for luminous environment improvement of tunnel space by using RADIANCE simulation program. The results of simulation show that illuminance of bar type is higher than illuminance of pole type at 20 m from the tunnel entrance.