• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.208-213
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• 2014

공동주택의 천장구조는 바닥충격음을 변화시키는 영향요소중의 하나이다. 천장구조의 진동응답 특성이 바닥충격음에 영향을 주는 요소를 확인하기 위해 천장구조의 달대를 제거하여 콘크리트 슬래브의 진동이 천장구조에 전달되지 않는 무달대 천장구조를 개발하였다. 달대가 시공된 일반 천장구조와 대비하여 무달대 천장구조의 천장판 가속도와 바닥충격음 레벨을 비교하였다. 무달대 천장구조를 사용함으로서 콘크리트 슬래브의 진동이 천장구조에 전달되는 것을 절연되어 천장구조의 진동응답 증폭을 저감시킬 수 있었으며, 저주파 대역의 바닥 충격음 증폭 또한 저감시킬 수 있었다. 일반 천장구조는 100 Hz 이하에서 천장구조의 진동응답이 증폭되어 저주파 대역 바닥충격음이 증폭되었다.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.229-234
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• 2005

This study aims to build basic data for a optimization of a ventilation system for indoor environment improvement in school building. To this end, we conducted field tests and computation fluid dynamics simulations about a indoor environment in dependence on operation of a ceiling type inverter air conditioner and ventilation system. The results could be summarized as follows. (1) For the ventilation system of 350CMH, 500CMH and 850CMH, reduction of each $CO_2$ concentration was measured 662ppm, 748ppm and 526ppm. (2) A optimal discharge angle of the ceiling type inverter air conditioner system was evaluated 45 degree in heating and cooling.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.1
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• pp.117-124
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• 1999

In this study, three different supply diffuser types(desktop, floor and ceiling) are compared in view of their ability to distribute supply air to the workstation breathing zone. The measurements on the age of air and the air change effectiveness using the tracer gas method are carried out to analyze the ventilation performance for provision of fresh air between the diffusers. The desktop diffuser type could deliver air directly to the occupants breathing zone with a high degree of effectiveness. The measured local air change effectiveness of the desktop diffuser in the breathing zone was usually 1.13 to 1.23 times greater than that of ceiling and floor diffusers. When the minimum outside air change rate as specified using ASHRAE Standard 62R is supplied with a desktop diffuser type, the volume of outside air can be reduced 13 to 23%, resulting in a commensurate in ventilation energy use.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.2
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• pp.156-160
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• 2008

A localization system to estimate the position as well as movement direction of mobile robots is proposed in this paper. This system implements a camera fixed on a robot and color patches evenly distributed and mounted on the planar ceiling. Different permutations of patch colors code information about robot localization. Thus, extraction of color information from patch images leads to estimation of robot position. Additionally, simple geometric indicators are combined with patch colors to estimate robot's movement direction. Since only the distribution of patch colors has to be known, the analysis of patch images to is relatively fast and simple. The proposed robot localization system has been successfully tested for navigation of sample mobile robot. Obtained test results indicate the robustness and reliability of proposed technique for robot navigation.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.2
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• pp.139-147
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• 2009

When the visually impaired walks inside a building like corridor, a GPS cannot be useful for the walker in estimating his or her position unlike the case of outdoor space. This paper presents two novel methods to measure the walking distance using a low cost camera worn on the chest of the visually impaired. In the first method we analyze the periodic variation of image focusing values. Walking steps are counted by checking the period for the rough measure of the walking distance. The second method counts the step number by monitoring fixtures on the ceiling, which have a certain interval. Lamps on the ceiling appeared on the video are monitored in this paper. The T-S fuzzy theory is used to detect lamps, and the walking steps are estimated by the positional variation of the lamp due to the gait of the walker. The two methods are tested in real experiment, and the results are compared.

• KIEAE Journal
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• v.2 no.1
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• pp.41-48
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• 2002

This study aims to investigate and evaluate the room acoustic designs of a multi purpose gymnasiums which do not use adjustable treatments in order to change the acoustical characteristics. Considering the main uses of gymnasium and auditorium, experiments were carried out using both nondirectional speakers on the stage and loudspeaker installed on the ceiling. The result from the study are as follows; Measured RT under unoccupied condition was a little longer than the expected value, therefore, in the case of occupied condition RT would be close to the optimum value. However, parameters that evaluate intelligibility and speech transmission property appeared to be low and have large differences depending on the measuring points, therefore, more effective sound reflecting surfaces and sound reinforcement systems should be considered.

• Journal of the Korean Institute of Educational Facilities
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• v.4 no.2
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• pp.13-20
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• 1997

The total evaluation of educational environment is needed with the rapid growth of the number of students. Especially it is very important to evaluate the physical environment of the classroom in elementary schools where the students spend their whole school life. This study aims to evaluate the daylighting and sound insulation performance of the classroom in elementary school, considering factors such as ceiling height and Wi/Wa (Window/Wall) ratio and then to plan the classroom. Analytic results of the daylighting and sound insulation performance show that the optimum Wi/Wa ratio is $35{\sim}45%$. Reduction of the ceiling height from 3.3m has little influence on the distribution of the indoor daylight factor and sound insulation performance

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.2 s.21
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• pp.14-21
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• 2005

This paper describes the system for detecting the tank crew's(loader's) hand, arm, head and the upper half of the body in a danger area between the turret ceiling and the upper breech mechanism by computer vision-based method. This system informs danger of pressed to death to gunner and commander for the safety of operating mission. The camera mounted ort the top portion of the turret ceiling. The system sets search moving object from this image and detects by using change of image, laplacian operator and clustering algorithm in this area. It alarms the tank crews when it's judged that dangerous situation for operating mission. The result In this experiment shows that the detection rate maintains in $81{\sim}98$ percents.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.25-29
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• 2003

As we know, topography of korea is composed of many mountains Also, the volume of traffic is increasing more and more nowadays. So, many tunnels are being constructed to reduce cost of transport and time. Thus, tunnel illumination was considered as the most important thing to make safe traffic conditions. In the past, we installed luminaires on the wall in tunnel, but currently we are installing those on the ceiling. Wherever luminaires are installed on the ceiling, the electric designer may not have known the proper point to install luminaires. Therefore, we researched this project to resolve above problems with abundant experience and accurate data through simulation(Lightscape program).

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.4
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• pp.15-21
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• 2011

The safety at this study is investigated by flow or stress analyses due to configuration or installation direction of fuel tank in the existing CNG bus. In case of the lower ceiling with sharp type, the equivalent stress due to the explosion of fuel tank is less than the type of flat or arc. it becomes safer on passenger. In case of the installation direction of fuel tank in the existing CNG bus, the stress applied on the lower ceiling at transverse direction becomes less than at longitudinal direction. It is more stable on the safety of passenger. The harm on the explosion accident can be prevented by use of the analysis result at this study.