• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.1
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• pp.31-39
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• 1997

This paper is on the vibration control of access floor on the frames of reinforced structure. In this study, the horizontal anti-vibration system using precise spring damper was developed and modeling and vibration analysis of the RC structure was performed for the control of horizontal vibration coused by machinery and worker's moving. Experiment was done in three cases, no damper at the RC structures, dampers connecting pedestal to pedestal and pedestal to the structure, for the investigation of the effect of the system on disigned RC structure. For each experiment, the occeleration responses on slab and access floor after giving impact wave and external vibration were measured. It was shown that the magnitude of resonance response of the system with dampers are smaller than without damper and the resonance peak also partly moved to low-frequency range. Furthermore. It was shown that the acceleration components of the system with domoers decreased greatly in high-frequency range and the system was very much effective especially for external vibration. In order to verify the anti-vibration effect of the developed system, the vibration analysis was also done for the system by using the finite element modelling. The analysis results was in good agreement with experimental results. Thus, It is concluded that this study is useful for the design of precise anti-vibration system and micro-vibration control of concrete structures.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.692-705
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• 2018

Ground vibration is one of the remarkable issues in tunnel blasting. In recent studies, to improve the fragmentation with reduction of ground vibration in tunnel blasting, a vibration-controlled blasting method with artificial cutting slot near the center-cut holes has been suggested. This study examines the effect of the different arrangement of artificial cut-slot on the vibration reduction and fragmentation by performing the full-scaled concrete block blast experiments and the numerical simulations with 3D-DFPA. The results show that the existence of artificial slot contributes to the improvement of vibration reduction, blast fragmentation and the efficiency of the cutting slot blast. It can be explained that the artificial slot play a free surface role and should decrease the burden between the cut holes. Crater volumes of the blasted concrete blocks were measured by 3-dimensional digital image analysis and compared with the ideal standard crater volume which can be calculated by theoretical standard blast design method. As a result, the ratio of burden and hole diameter which should achieve the standard crater in the cut-hole blasting were suggested.

• Journal of Broadcast Engineering
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• v.15 no.6
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• pp.715-722
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• 2010

As one of applications in augmented realities, this paper presents a bubble popping system utilizing a haptic vibro-tactile mouse. In this system, virtual bubbles randomly float in the 3D space. By using the vibro-tactile mouse grabbed by a user, the bubbles are popped when they are touched by the mouse in the 3D space. Then a bubble popping effect with addition mouse vibration is delivered to the user's hand through the mouse. The proposed system is developed on ARToolkit environment. Therefore, basic components such as a camera and a marker pattern are required. The systems is composed of a vibro-haptic mouse, a webcam, a marker pattern, a graphic bubble object, and graphic mouse. Mouse vibration as well as bubble fade-out effect is delivered. Therefore, the combination of visual and tactile bubble popping effects outperforms the usage of a single effect in the experience of augmented reality.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.85-90
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• 1990

오늘날 산업구조의 발달과 경제적인 향상으로 정보교환의 가속화와 대중매 체의 비약적인 발전을 가져왔다. 그중 TV는 정보의 광역성과 전달의 가속성 으로 인하여 현대인의 생활에서 큰 부분을 차지하게 되었고, 이로 인한 정보 의 홍수속에서 상품에 대한 정보를 제공하는 광고가 생활속에 깊숙이 침투 되기에 이르렀다. TV광고는 시각(sight), 음향(sound), 동작(motion), 색체 (color)를 동시에 사용하기 때문에 라디오보다 더욱 큰 효과를 주고 있으며, 특히 소리효과는 음향효과와 음악효과를 총칭한 것으로 현란한 소리 효과를 넣어서 듣는 사람에게 괴로움을 야기시킨다. 이러한 효과는 사람들에게 건 강, 작업능률 및 심리적 장애를 일으킨다. 70년대 이후 집합주택의 양적인 성장과 함께 아파트 내부의 소음은 공해중 큰 부분을 차지하며, 정상적인 생 활과 쾌적한 환경에 문제를 던져주고 있다. 따라서 본 연구는 TV의 광고 및 드라마 소음의 물리적 측정과 아파트 주민들의 주관적 반응을 조사 및 분석, 고찰하여 안락한 주거내에서 고른 음향으로 TV를 시청하고 조용한 주거생 활을 누릴 수 있는 기초자료를 제시하는데 그 목적이 있다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.215-220
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• 1996

원자력발전소의 주증기관은 증기발생기와 터빈을 연결하는 주요 계통으로서 여기서 발생하는 배관진동은 주요기기의 연결부, 밸브, 배관지지물과 건물 등에 복합적인 반복하중을 가하여 관련 지지물 및 구조물에 열화현상을 발생시켜 발전소의 안전운전에 심각한 영향을 초래할 가능성을 항상 내포하고 있다. 그럼에도 불구하고 배관진동 대책은 대부분 지지물을 추가로 설치하여 진동준위만 낮추고 있는 실정이다. 따라서 구체적인 배관진동의 예측, 측정 및 평가, 감쇠방안에 이르는 종합적이고 체계적인 연구가 요구되고 있다. 본 연구에서는 지지물의 열화현상 및 부분적인 파손으로 진동준위가 높아진 것으로 추정되는 원자력발전소 주증기관의 진동특성 및 요인을 분석하여 진동감쇠 방안을 도출하고 검증함으로써 배관 및 주변 구조물의 건전성을 확보하고 설비의 신뢰성을 확보하고자 하였다. 이를 위하여 주증기관을 모델링하여 해석하였으며, 발전소의 기동 및 정상운전시의 진동준위를 측정하였다. 또한 발전소의 정진기간중 일부 배관계에 대한 실험적 모우드 해석을 수행하였다. 여러가지 진동감쇠 방안을 검토하여 탄성지지 및 에너지 흡수효과를 동시에 발휘할 수 있는 특수 지지물(WEAR$_{TM}$)을 설치하는 방안을 도출하였으며, 현장에 설치한 후 배관의 진동상태를 확인함으로서 효과적인 방안임을 검증하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.187-190
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• 2010

기초세굴에 따른 교각에서의 1차 모드 고유진동수 변화를 이용하여 교량 세굴 건전성을 정량적으로 평가하기 위하여 공용중인 광탄1교의 T형 교각 1기에 대하여 충격진동실험을 수행하였으며, 교축직각방향의 1차 모드 고유진동수를 수치해석결과와 비교하였다. 교량 상부구조물의 모델링 방법에 따라 상부구조물을 전체 모델링한 방법과 교각만을 모델링하고 상부구조물의 영향범위를 가정하여 교량받침 위치에 질점질량으로 변환하여 적용한 방법으로 구분하여 수치해석을 수행하였다. 상부구조물을 전체 모델링한 경우와 집중하중 형태로 상부구조물을 모델링한 경우 모두 고유진동수는 충격진동실험결과와 큰 차이를 보였다. 충격진동실험을 통해 얻은 고유진동수는 교각의 국부적인 진동수로 사료되는 반면, 수치해석을 통해 구한 결과는 교량 상부와 하부의 Coupling 효과가 반영된 시스템 전체의 고유진동수이기 때문에 결과의 큰 편차가 생기는 것으로 판단된다. 따라서 충격진동실험에서 구한 고유치 양상을 올바로 구현하기 위한 모델링을 찾기 위해서는 새로운 접근 방법이 필요할 것으로 사료된다.

• Journal of the Korea Society of Computer and Information
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• v.15 no.2
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• pp.75-81
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• 2010

Feeling of shooting is one of the most important features of shooting games. Game developers have tried to improve feeling of shooting by using various techniques, such as visual/sound effects, rumble effects, animations, and camera techniques. In this paper, we introduce the results of the empirical analysis of the several techniques in a 2D shooting game. We carried out two experiments in which levels of feeling of shooting were measured in a simple 2D shooting game. The first experiment was configured with 16 combinations of the four techniques (visual, animation, sound, and rumble effects) applied to a shooting object (a cannon), and the second was configured with 16 combinations of the two techniques (visual and sound effects) applied to both or either side of a shooting object and exploding objects (enemy ships). The analysis results of the experiments showed that all of each techniques were statistically significant factors. We could also found that sound effects and rumble effects are more effective than visual effects and animations and that exploding objects are more important that a shooting object.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.171-179
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• 2021

This study was a meta-analysis of previous studies that subjected stroke patients to the whole-body vibration exercise, in an attempt to evaluate the effectiveness of such exercise in improving their balance and walking ability. The electronic databases used for literature search were the National Assembly Library, Korean Educational Academic Information (RISS), Korean Academic Information (KISS), and Nuri Media (DBPIA). We also investigated a prior study of the whole-body vibration exercise applied to stroke patients from January 2010 to August 2020. In assessing the quality of the study, the RCT (randomized controls trials) study used the risk of bias 2 (RoB2) tool developed by the Cochrane group. Meta-analysis was performed using R software for statistical computing version 4.0.3. The results of the study confirmed that the overall effect size was 0.40, and the whole-body vibration exercise used had a moderate effect on the balance and gait of stroke patients, the effect size of balance was 0.44, and the effect size of gait was 0.36, showing a positive effect. These results indicated that the whole-body vibration exercise is an effective intervention for stroke patients, and further research is needed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.2
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• pp.125-131
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• 2003

In this paper Power Flow Finite Element Method(PFFEM) has been implemented to analyze the vibration of a plate in mid and high frequency ranges. In order to solve the vibration energy governing equation in Power Flow Analysis(PFA), The Finite Element Method(FEM) was used as a numerical tool. It allowed one to predict the distribution of displacement and Intensity in the plate vibrating at mid and high frequencies. The results were compared with the analytical solutions and the approximate FEM solutions. The comparison showed that PFFEM can be an effective tool to analyze the structural vibration in mid and high frequency ranges.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.2
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• pp.39-48
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• 1997

New form of base isolators made of steel spring coated with both natural and artficial rubber were manufactured and tested for material properties. Shaking table experiments were performed using a model structure attached with the bearings. The model structure used in the test is a 1/4 scaled steel structure, and earthquake records were used to check the lateral and vertical stability and effectiveness of the isolators. According to the results all three types of isolators turned out to be effective in reducing the acceleration induced by the earthquake vibration.