• 자동차안전학회지
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• 제4권1호
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• pp.5-11
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• 2012

This paper discusses the evaluation of the safety impact of the Adaptive Cruise Control (ACC) system in Korea. To evaluate the safety impact, this paper suggests an analysis method by using the test scenario and field operational test data. The test scenario is composed to represent the main component factor of the ACC system and ACC related accident situation such as rear-end collision, lane-change, and road-curvature, etc. Also, from the field operation test data, the system's potential to increase the safety can be measured ideally. Besides, field operational testdata was used to revise the expected safety impact value as Korean road conditions. By using the proposed evaluation method, enhanced safety impact of the ACC system can be estimated scientifically.

• International Journal of Safety
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• 제4권1호
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• pp.1-7
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• 2005

The direction of the applied load and displacement rate on the femur during falls may be an important factors in the etiology of hip fractures. Nonetheless, previous studies did not consider these two factors simultaneously for falling condition. Therefore, in the present study, an impact test system is developed to simulate the falling condition and the influence of impact angle on the deformation pattern changes of proximal femur is investigated. The results showed that a slight variation in impact angle quite affects deformation pattern of the proximal femur. Along with bone mineral density and trabaecular morphology, the impact angle can be another important factor affecting the structural capacity of the proximal femur.

• 대한기계학회논문집A
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• 제26권1호
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• pp.153-159
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• 2002

Brittle materials such as ceramics and glasses show fragile fracture due to the low toughness and the crack sensitivity. When brittle materials are subjected to impact loading by small spheres, high contact pressure occurs to the surface of the specimen. Local damage is subsequently generated in the specimen. This local damage is a dangerous factor which gives rise to the final fracture of structures. In this research, impact damage of soda-lime glass plates by small spheres was evaluated by considering the effects of impact directions of indenter, pressure condition of specimen and residual strength after impact loading.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.52-59
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• 2013

The use of economic incentives to improve H&S performance in the construction industry in general, has been investigated by various scholars. However, few studies have looked at the impact of economic incentives on construction clients especially in the developing world. Therefore it was necessary to investigate specifically the impact of the economic incentive on client's H&S performance. Economic incentives are considered to be a proactive way of improving H&S performance. The investigation was conducted using a Delphi technique to determine the impact significance of the economic incentive or disincentive on construction clients' H&S performance. Findings from the study were that the economic factor had critical impact significance on clients' H&S performance. Further clients were 'very likely to' implement various H&S elements as a result of the economic incentive and disincentive. The paper will report on the findings from an analysis of impact significance of the economic incentives on clients. It will underscore the point that economic incentives or disincentives on construction clients are necessary to encourage them to actively participate in H&S performance improvement.

• 환경영향평가
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• 제16권6호
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• pp.511-524
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• 2007

Korea has 30 years of experiences in environmental impact assessment (EIA). Although EIA includes sanitation-public health factor, considering health impacts, among 74 unit projects of 17 sections, health impacts haven't been properly considered or have been ignored in many cases. The increasing awareness on the importance of health impacts has triggered this study to seek an optimal introduction scheme of health impact assessment (HIA). The processes of EIA already include screening, scoping, analysis, impact assessment, consultation, document review, decision making and monitoring, in which they would be the essential parts of HIA. In this context, integrating HIA into the existing EIA process could be the most effective way to use the benefits in both legal and procedural processes existed and to avoid the confusion and overlapping since the close relationships between environment and health impacts might be. Furthermore, it is desirable that the existing sanitation-public health factor should be substituted by and extended to environment-health factor with sufficient determinants to properly consider health impacts. When considering the first step of HIA, the prospective and qualitative approach is suitable more than the retrospective and quantitative one due to the lack of database accumulated. Similarly, an approach based on epidemiology and toxicology could analyze the limited evidences and impacts related to human disease, whereas one based on socio-science and psychology could provide the effective means available for predicting how the people and community will act by the change of surroundings. Checklist approach with various and comprehensive health determinants focused on prospective and qualitative methods will be very useful for more convenient and progressive dissemination of HIA. Various checklist approaches of toolkits could be found from HIA documents elsewhere, for example Westminster Toolkit, and they would be helpful to figure out how to develop common procedures and health determinants for checklist, in which the unique characteristics on korean cultural and political context compared to abroad should be carefully considered since checklist would be the most basic and essential part of HIA. After the establishment of checklist and procedural processes, the pilot projects should be conducted. Main purpose of pilot projects is to apparently prove the effectiveness and profitability of HIA. Pilot projects should be implemented to decide the effectiveness and suitability of HIA for future projects, programs and policies, and should be provided as the positive cases that can be achieved through the proper implementation and progress.

• 대한인간공학회지
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• 제28권3호
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• pp.33-39
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• 2009

Impact force to a body during walking depends on walking speed, walking steps, the condition of the floors and shoes, and weight. The ground reaction force and the foot pressure can be measured instantaneous force easily, but it's difficult to find out the amount of transferring forces to the body. On the other hand, the acceleration has an advantage for analyzing the amount of transferring forces. However, most of studies about impact forces to the ground reaction during exercise have been limited to analyze instantaneous forces. The important thing is to evaluate characters and the amount of the impact force rather than the magnitude. Therefore, this study analyze the impact force using 3 axis acceleration in three dimensions (x; anterior-posterior, y; left-right and z; longitudinal axis) using three axis acceleration. As working speed increased, impact forces increased significantly. Impact forces on x axis and z axis are higher at lower limb than that of upper limb. However, impact force at the knee is higher than that of other parts on y axis regardless of walking speed significantly. In addition, relations of the impact forces as interaction of experiment factors as well as effect of each factor are analyzed.

• 한국정밀공학회지
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• 제10권4호
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• pp.152-162
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• 1993

The purpose of this study is to investigate problems of residual bending strength and the impact damage experimentally when CFRP composite laminates are subjected to Foreign object damage. The specimens composed of four types of CR/EPOXY and a CF/PEEK composite laminates which involved difference of fiber stracking orientation and matrics. The result were summariged as follows : 1) It is found that both orthotropic and guasi-isotropic composite laminates are increasimg lineally between impact energy and damage delamination area. 2) Delamination devel- opment energy(mm$^{2}$J) OF cf/epoxy composite aminates is less than that of CF/PEEK. 3) When impact energy is applied to specimens within 3J, the residual strength of orthotropic is greater than guasi-isotropic composite laminates. On the other hand, it is predicted that residual bending strength of orthotropic composite laminates is less than that of quasi-isotropic when impact energy is more thaen 3J. 4) It is found in CF/PEEK that for the impact side compression, residual of bending strength versus impact energy is almost constant, while in case of impact side tension, residual bending strength is decreased rapidly near 1.2J. of impact energy due to the effect of delamination buckling.

• 환경영향평가
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• 제14권4호
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• pp.165-177
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• 2005

This study was carried out to offer the basic methodology of the system and model to objectively assess the natural ecosystem for environmentally friendly land conservation and present the alternative plan on establishing the environmental policy. The results of this study were as follows. We selected four assessment factors associated with biotic, abiotic, qualitative, and functional factors. Also, there were extracted fifty-six indicators including density, total nitrogen, hemeroby degree, and goods production. The assessment factor showed that biotic one was very important. The importance of indicators were analyzed that rare and endangered plant was important in biotic factor, in case of abiotic, qualitative, and functional factors, organic matter, landscape diversity, and conservation of ecosystem were greatly important. The results of factor analysis on the characteristics of indicators, classified biotic factor into six factors including a structural one, abiotic factor as a soil and physical one, qualitative factor as five ones including hierarchical one, and functional factor as public and conservational one. In the results of analysis on assessment model, R-square of biotic factor was 51.7%, those of abiotic, qualitative, and functional one were each 58.4%, 44.2%, and 39.3%, and statistical problem was no existence. In future, to develop the assessement model and methodology of sustainable natural ecosystem, we will have to achieve the integrated model and grouping by assessment factor.

• Structural Engineering and Mechanics
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• 제47권5호
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• pp.643-660
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• 2013

In the present work, the capacity ratings of steel truss bridges have been carried out incorporating dynamic effect of moving vehicles and its accumulating effect as fatigue. Further, corrosion in the steel members has been taken into account to examine the rating factor. Dynamic effect has been considered in the rating procedure making use of impact factors obtained from simulation studies as well as from codal guidelines. A steel truss bridge has been considered to illustrate the approach. Two levels of capacity ratings- the upper load level capacity rating (called operating rating) and the lower load level capacity rating (called inventory rating) were found out using Load and Resistance Factor Design (LRFD) method and a proposal has been made which incorporates fatigue in the rating formula. Random nature of corrosion on the steel member has been taken into account in the rating by considering reduced member strength. Partial safety factor for each truss member has been obtained from the fatigue reliability index considering random variables on the fatigue parameters, traffic growth rate and accumulated number of stress cycle using appropriate probability density function. The bridge has been modeled using Finite Element software. Regressions of rating factor versus vehicle gross weight have been obtained. Results show that rating factor decreases when the impact factor other than those in the codal provisions are considered. The consideration of fatigue and member corrosion gives a lower value of rating factor compared to those when both the effects are ignored. In addition to this, the study reveals that rating factor decreases when the vehicle gross weight is increased.

• Geomechanics and Engineering
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• 제33권2호
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• pp.141-154
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• 2023

This study investigated the effect of water retention characteristics between aged and fresh Municipal Solid Waste (MSW) on the stability of the landfill. A series of transient numerical modeling for the slope of an MSW landfill was performed considering the variation of water retention characteristics due to leachate circulation. Four different scenarios were considered in this analysis depending on how to obtain hydraulic conductivity and the aging degree of materials. Unsaturated hydraulic properties of the MSW used for the modeling were evaluated through modified hanging column tests. Different water retention properties and various landfill conditions, such as subgrade stiffness, leachate injection frequency, and gas and leachate collection system, were considered to investigate the pore water distribution and slope stability. The stability analyses related to the factor of safety showed that unsaturated properties under those varied conditions significantly impacted the slope stability, where the factor of safety decreased, ranging between 9.4 and 22%. The aged materials resulted in a higher factor of safety than fresh materials; however, after 1000 days, the factor of safety decreased by around 10.6% due to pore pressure buildup. The analysis results indicated that using fresh materials yielded higher factor of safety values. The landfill subgrade was found to have a significant impact on the factor of safety, which resulted in an average of 34% lower factor of safety in soft subgrades. The results also revealed that a failed leachate collection system (e.g., clogging) could result in landfill failure (factor of safety < 1) after around 298 days, while the leachate recirculation frequency has no critical impact on stability. In addition, the accumulation of gas pressure within the waste body resulted in factor of safety reductions as high as 24%. It is essential to consider factors related to the unsaturated hydraulic properties in designing a landfill to prevent landfill instability.