• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.11a
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• pp.81-86
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• 2001

산업의 발전과 함께 소비3자의 욕구는 제품의 질적, 감성적 향상을 요구하고 있으며, 또한 최근 각종 공학의 눈부신 발전에 힘입어서 자동차의 성능, 안락성 등이 크게 향상되면서 운전자의 운전 중 피로감 제거에 관심이 높아지고 있다. 본 연구는 주관적인 피로감 평가 방식 중 졸림감(KSS), 피로감 용어 및 신체 불편도를 이용하여 평가를 수행하였다. 졸림감 및 피로감 용어는 차종 및 자세에 따라 약간의 차이가 있었지만, 대체적으로 시간이 지남에 따라 불편함의 정도가 심해졌다. 신체 불편도에 대한 평가결과 엉덩이, 요추, 어때, 좌우 발목 부위가 불편한 것으로 나타났다. 이러한 결과들은 차종별 또는 운전자세에 따라 통계적으로 유의한 차이를 보이기도 했다. 이러한 연구 결과를 통해서 동환경 시스템의 기초 데이터를 확보할 뿐만 아니라, 자동차를 설계하는데 있어, 보다 안락하고 편안한 운전환경을 만들 수 있는 기초자료로써 활용이 가능할 것이다.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.3
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• pp.107-113
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• 2016

Visual discomfort is a common problem in three-dimensional videos. Among the methods to overcome visual discomfort presented in current research, disparity adjustment methods provide little guidance in determining the condition for disparity control. We propose a diaprity adjustment based on the characteristics of disparity distribution on visual comfort, where the visual comfort level is used as the adjustment paramter, in parallax barrier type auto-stereoscopic 3D display. In this paper, we use the horizontal image shift method for disparity adjustment to enhance visual comfort. The speeded-up robust feature is used to estimate the disparity distribution of 3D sequences, and the required amount for disparity control is chosen based on the pre-defined characteristics of disparity distribution on visual comfort. To evaluate the performance of the proposed method, we used a 3D equipment. Subjective tests were conducted at the fixed optimal viewing distance. The results show that comfortable videos were generated based on the proposed disparity adjustment method.

• Journal of Korean Society of Steel Construction
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• v.18 no.1
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• pp.11-22
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• 2006

Message Signs (VMS) structures offer an increase in traffic safety through their ability to relay massages to motorists for warnings of hazards ahead, traffic congestion, accidents, and lane closings. The geometry of these signs sometimes results in the significant cyclic loading of the supports structure due to wind gusts, which can result from passing trucks or from natural wind. This study presents the results of analytical and experimental investigations of VMS structures. The commercially available softwareGTSTRUDL (2003) was used to perform space-frame structural analyses of these welded tubular structures. Fatigue evaluations were performed using stress ranges from field measurements and from structural analyses. Based on the results of the structural analyses that were conducted, where fatigue design loadings that had been derived from AASHTO Specifications for Structural Supports for Highway Signs, Luminaries, and Traffic Signals (2001) were used, the structures that had been studied were found not to have infinite fatigue life. According to the limited measurements that were made in this study, the fatigue design loadings derived from AASHTO Specifications (2001) appear to be conservative, but they are not overly conservative. The results of this study should be used to make a reasonable design of VMS structures, and to maintain their standards.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1A
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• pp.71-80
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• 2010

Bridge deck is directly influenced by environment and vehicle load, it is easily damaged so that it requires an appropriate repair and retrofit. Therefore, developing a bridge deck with high durability is necessary in order to minimize the maintenance of bridge deck and use it to its design life. In this study, static test was carried out to evaluate a fatigue capacity of steel-concrete composite deck, which was newly developed by supplementing problems of existing reinforced concrete deck. Based on results from the static test, fatigue load was decided, and fatigue test was conducted under the constant amplitude repeated load. From the fatigue tests, the S-N curve regarding principle structural details of composite deck was made, and characteristics of fatigue behavior was estimated by comparing and evaluating it with fatigue design criteria. In addition, fatigue design guideline was presented. As a result, it is found that each structural details of composite deck proposed by this study, such as upper flange of corrugated steel plate and middle section of it, shear connector and lower flange of corrugated steel plate, is satisfying the fatigue strength.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.39-45
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• 2024

Seismic safety of expansion joints for piping systems has been underscored by water pipe ruptures and leaks resulting from the Gyeongju and Pohang earthquakes. Metal bellows in piping systems are applied to prevent damage from earthquakes and road subsidence in soft ground. Designed with a series of corrugated segments called convolutions, metal bellows exhibit flexibility to accommodate displacements. Several studies have examined variations in convolution shapes and layers based on the intended performance to be evaluated. Nonetheless, the research on the seismic performance of complex bellows having multiple corrugation heights is limited. In this study, monotonic loading tests, cyclic loading tests, and fatigue tests were conducted to evaluate the shear performance in seismic conditions, of metal bellows with variable convolution heights. Single- and triple-layer bellows were considered for the experimentation. The results reveal that triple-layer bellows exhibit larger maximum deformation and fatigue life than single-layer bellows. However, the high stiffness of triple-layer bellows in resisting internal pressure poses certain disadvantages. The convolutions are less flexible at lower displacements and experience leakage at a rate related to the variable height of the convolutions in certain conditions. At lower deformation rates, the fatigue life is rated higher as the number of layers increase. It converges to a similar fatigue life at higher deformation rates.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.1
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• pp.41-47
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• 2009

Transverse rib web of orthotropic steel decks is highly susceptible to stress concentration due to out-of-plane and oil canning deformation caused by longitudinal rib distortion. In particular, stress concentrations are observed in the crossing point of longitudinal rib-transverse rib-deck plate, and cutout parts of transverse rib. The main objective of this study is to improve structure performance and to reduce the stress concentration of aforementioned susceptible parts. It is known that the installation of diaphragm alleviates stress concentrations between crossing point ant cutout. The influence of transverse rib placement and cutout width on stress concentrations was thoroughly investigated through numerical analyses. The numerical result showed that diaphragms produce the structural details for improved structure performance, when the transverse rib was placed in the same location with diaphragms. In any case, it is certain that the installation of diaphragms has more advantageous than the case without diaphragms in terms of structure performance of orthotropic steel decks. In this study, the distance ratio($y_i/y_{total}$) is defined as the ratio of the distance($y_{total}$) between the deck plate and longitudinal rib bottom to the distance($y_i$) between the deck plate and crossing point of longitudinal rib-transverse rib in cutout part. It has been found that the optimal distance ratio was 0.85 from the numerical simulation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.1
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• pp.123-130
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• 1988

Two kinds of 16bit-personal computer-based fatigue testing automation and monitoring system were constructed; one is Single-System utilizing a personal computer, the other si Dual-System consisting of two personal computers. The system developed in this study permits to perform multi-step programmed loading and pseudo-random loading fatigue tests, three parameters such as load, total displacement and subtracted displacement can be measured simultaneously. For improvements in measurements of fatigue behavior, two kinds of signal noise reduction software was developed. In addition, a software was also designed to automatically measure the crack opening point and crack length using the unloading elastic compliance technique.

• Proceedings of the ESK Conference
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• 1997.04a
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• pp.150-155
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• 1997

VDT의 한글 화면을 탐색하는데 있어 가독성에 영향을 주는 요인에 대한 연구는 한글 VDT 화면의 표준지침 선정의 기초자료로서 중요하게 활용될 수 있으나 그 연구가 부족한 실정이다. 영어와 한글의 글자체계에는 차이가 있어 외국의 연구결과 및 표준지침을 적용하는 것은 무리가 있기 때문에 한글 글 자체계에 대한 쳬계적이고 인간공학적 연구가 시급하다 할 수 있다. 이에 본 연구에서는 글자크기와 서체(font)를 선정하여 사용자의 시각성능과 관련하여 최적의 수행도 및 피로도를 경감하여 주는 서체와 글자크기 수준을 실험을 통하여 제시하였다. 그 결과는 다음과 같다. (1) VDT 화면에서 한글 고딕체가 명조체보다 사용자의 시각성능 및 수행도가 우수하다. (2) 초적의 수행도를 주는 글자크기는 명조체의 경우 35.4' .approx. 55.5', 고딕체의 경우 시각 39.8 .approx. 52.6'이다. (3) 우수한 수행도를 보이는 글자크기에서 피로도 저하율이 낮게 나타난다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.11a
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• pp.22-22
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• 1997

무공해 에너지원은 화석에너지의 고갈과 환경오염의 심각한 문제로 인하여 절실히 요구되고 있는 실정이다. 그중 풍력발전 시스템은 타 에너지원에 비해 여러 가지 측면에서 유리한 점을 가치고 있다. 본 연구에서는 500Kw급 풍력발전 시스템을 개발함에 있어, 적합한 공력 성능 및 구조성능을 가지는 회전날개 설계과정을 수행하였다. 공력설계는 운용지역의 풍황을 고려하여 회전날개의 외형을 결정하였고 이를 바탕으로 공력성능해석이 수행되었으며, 구조설계는 복합재료를 사용하여 쉘-스파 구조를 갖도록 설계하여 굽힘 및 비틀림 그리고 피로수명에 대한 구조해석이 수행되었다. 그 결과 4m/s의 미풍에서도 운용가능하며, 12m/s에서는 정격출력 550Kw를 생산할 수 있는 형상이 설계되었고, 또한 20년 이상의 피로수명이 확보되었으며, 공질 등의 동적인 문제도 발생하지 않음을 확인하였다.

• Journal of Ocean Engineering and Technology
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• v.20 no.5 s.72
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• pp.82-88
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• 2006

This assessment is concerned with the fatigue strength of the tendon porch found in TLP. Lorge-scale fatigue tests with models constructed at 30% the size of the real structures have been carried out to investigate the fatigue behavior of the API 2W Grade 50 steel recently produced by POSCO. The fatigue life for the present test models was obtained based on the concept of nominal stress. A comparison of the present test results with those obtained by a numerical approach based on the structural analysis results has showngood agreement. The present results were also compared with the design curves in DnV RP-C203.