• 환경영향평가
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• 제1권1호
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• pp.51-59
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• 1992

Environmental Impact Assessment(EIA) is defined as an activity designed to identify and predict the impact on the environment. In the process of an EIA, the quantitative evaluation is generally performed for the air and water quality which have the national environmental quality standards. But the predicted values for the air and water quality are simply compared to the environmental standards. At present, the EIA process of Korea has no consideration for the possible human health risk resulting from the development projects. Environmental Health Impact Assessment(EHIA) is an applied methodology of EIA to estimate the acceptable health risk caused by a specified level of environmental pollutants. Estimating the excessive lifetime risk that is a possibility of dying of a certain disease by environmental contaminants, is useful as an evaluation technique of EHIA. It is recommanded the decision-makers to make efficient use of EHIA not only the development projects but also legislative proposals, policies and programmes in future.

• International Journal of Aeronautical and Space Sciences
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• 제14권2호
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• pp.140-145
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• 2013

The development of high performance fabrics have advanced body armor technology and improved ballistic performance while maintaining flexibility. Utilization of the shear thickening phenomenon exhibited by Shear Thickening Fluids (STF) has allowed further enhancement without hindering flexibility of the fabric through a process of impregnation. The effect of STF impregnation on the ballistic performance of fabrics has been studied for impact velocities below 700 m/s. Studies of STF-impregnated fabrics for high velocity impacts, which would provide a transition to significantly higher velocity ranges, are lacking. This study aims to investigate the effect of STF impregnation on the high velocity impact characteristics of Kevlar fabric by effectively dispersing silica nanoparticles in a suspension, impregnating Kevlar fabrics, and performing high velocity impact experiments with projectile velocities in the range of 1 km/s to compare the post impact characteristics between neat Kevlar and impregnated Kevlar fabrics. 100 nm diameter silica nanoparticles were dispersed using a homogenizer and sonicator in a solution of polyethylene glycol (PEG) and diluted with methanol for effective impregnation to Kevlar fabric, and the methanol was evaporated in a heat oven. High velocity impact of STF-impregnated Kevlar fabric revealed differences in the post impact rear formation compared to neat Kevlar.

• 한국정보통신학회논문지
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• 제3권4호
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• pp.915-922
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• 1999

본 논문에서는 GaAs 풀밴드 E-k관계를 이용하여 전계방향에 따라 임팩트이온화가 전자전송에 미치는 영향을 분석하였다. E-k관계를 구하기 위하여 페르미황금법칙과 local form factor를 이용하는 의사포텐셜방법을 사용하였으며 임팩트이온화율을 구하기 위하여 브릴로우인영역을 사면체로 분할하여 각 사면체마다 적분하는 사면체방법을 이용하였다. 임팩트이온화의 이방성분석을 위하여 Monte Carlo시뮬레이션을 수행하였다. 특히 임팩트이온화의 과도상태분석을 수행한 결과, 이방성은 과도상태에서만 발생하는 것으로 나타났으며 정상상태에서는 등방성 특성을 보이는 것으로 나타났다. 본 연구에서 제시한 GaAs 임팩트이온화의 이방성특성은 GaAs 소자의 과도응답특성분석에 사용될 수 있으리라 사료된다.

• 대한기계학회논문집
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• 제18권5호
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• pp.1158-1168
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• 1994

For BEM analyses of the impact problems of dissimilar materials, the connected multi-region method using perfect bonded conditions on the interface boundaries was added to two-dimensional Laplace transformed-domain BEM program for a single region analysis. It was confirmed that the BEM results of impact problems of a single-region and multi-regions for a homogeneous isotropic material are agreed well. The two-dimensional Laplace transformed-domain BEM program combined with connected multi-region method was applied to analyse several impact problems of dissimilar materials. Also the feasibility of BEM impact analyses was investigated for dissimilar materials by the analysis of the BEM results for impact problems of dissimilar materials in terms of physical aspects. As for an application, the two-dimensional Laplace transformed BEM concerning impact problems of cracks at the interface of dissimilar materials and the determinating process of the dynamic stress intensity factors by extrapolation method are presented in this paper.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1803-1806
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• 2007

The General roles of a spacer grid(SG) are providing a lateral and vertical support for fuel rods, promoting a mixing of coolant and keeping guide tubes straight so as not to impede a control rod insertion under any normal or accidental conditions. To evaluate the impact characteristics of a SG such as impact velocity, critical buckling strength and duration time, a few types of impact tests for SGs have been conducted. In a previous study, a new welding method, a through-welding method, was proposed to increase critical buckling strength of a SG without any design change or material change and was verified by impact tests with $7{\times}7$ partial SG specimens.In this paper, the effect of through-welding method in case of a $16{\times}16$ full-size SG is investigated by pendulum impact tests with $16{\times}16$ SG specimens. And the increase of critical buckling strength for full-size SGs is measured by comparison with impact results of spot-welded and through-welded SGs.

• 한국소음진동공학회논문집
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• 제27권1호
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• pp.5-13
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• 2017

Noise complaints among neighbors in apartment building are mainly caused by floor impact noise that is structure born noise due to occupant induced floor vibration. To control this noise problems many researchers have investigated floor systems and finishing materials. Light-weight impact noise affects by finishing materials, but heavy-weight impact noise induced by heel impacts during normal walking or jumping of children is concerned with structural system and floor vibration. To figure out the characteristics of floor impact noise and transmission of floor vibration due to human activities, vibration tests were conducted in apartment buildings. Impact hammer, heel drop and walking activities were loaded at center of upstairs living room, and accelerations of slabs for both upstairs and downstairs and sound pressure levels for downstairs were measured. The acceleration ratio of transmitted floor vibration to downstairs and human induced vibration in upstairs was between 0.5 and 1.0 according to slab size, wall, and load type. And floor impact noise occurred in the range of natural frequency of slab.

• 한국치위생학회지
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• 제6권1호
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• pp.13-23
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• 2006

A number of studies are beginning to show that oral disorders can have a significant impact on the functional, social and psychological well-being of adult. The aim of this study was to measure, the Oral Health Impact Profile(OHIP), which has recently been tested in studies of oral health of adult aged 55 years and older. The sample consisted of 380 adults The measure proved to be reliable and valid, while data collected using this measure indicated that oral conditions have negative impact on the daily, this impact was particularly marked among both edentulous and dentulous individuals who did not make regular visits for dental care. The relationship between the OHIP 7 demention compared with the group based on their dental state and age group was statistically Signification(pE0.01) people with denture were more likly to report having many problems in all seven dimention corvered by OHIP scale than those with natural teeth only These results indicated that the OHIP has a negative impact on the daily lives of a substantial proportions of older people. This impact was particularly noticeable among the edentulous and denture wearers.

• 수산해양기술연구
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• 제32권4호
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• pp.421-431
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• 1996

From comparing the impact dynamic absorber with the impact damper in the auxiliary vibration system with the conventional dynamic absorber, the following conclusions are obtained as follows ; 1. Recognizing that the amplitude restraining effect of the impact dynamic absorber become resonable in a comparison of conventional one development of an improved dynamic absorber may be probable. 2. With increasing the frequency ratio, the 1st resonance peak is higher but the 2nd one gets lower. In addition, the frequency ratio is peak located at the same resonance. 3. The optimum impact clearance is smaller and the vibration constraining effect becomes better with and increase in the mass of impact ball. And it is recognizable that the optimum tuning frequency ratio and impact clearance in an accordance with the mass ratio are varied. 4. The optimum tuning condition becomes gradually lower than the case of r=1 and maximum amplitude becomes lower with an increment in the mass ratio. However, the impulse clearance is larger and the working range of restraining vibration amplitude become smaller with a decrement in the mass of impact ball.

• 수산해양기술연구
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• 제45권3호
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• pp.188-193
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• 2009

The present study was undertaken to evaluate the effect of temperature on the results of Charpy impact test for glass fiber reinforced polyurethane(GF/PUR) composites. The Charpy impact test were conducted in the temperature range from -50$^{\circ}$ to 50$^{\circ}$. The impact fracture toughness of GF/PUR composites was considerably affected by temperature and it was shown that the maximum value was appeared at room temperature. It is believed that sensitivity of notch on impact fracture energy were increased with decrease in temperature of specimen. As the GF/PUR composites exposed in low temperature, impact fracture toughness of composites decreased gradually owing to the decrease of interface bonding strength caused by difference of thermal expansion coefficient between the glass fiber/polyurethane resin. And decrease of interface bonding strength of composites with decrease in specimen temperature was ascertained by SEM photographs of Charpy impact fracture surface.

• Structural Engineering and Mechanics
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• 제62권3호
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• pp.373-380
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• 2017

Concrete structures are often subjected to long-term static and short-term dynamic loads. Due to a relatively low tensile strength and energy dissipating characteristics, the impact resistance of concrete is considered poor. This study investigates the feasibility of using polypropylene fibers to improve the impact resistance of reinforced concrete slabs. Fourteen polypropylene fiber reinforced concrete slabs were fabricated and tested using a drop weight test. The effects of slab thickness, fiber volume fractions, and impact energy on the dynamic behaviors were evaluated mainly in terms of impact resistant, crack patterns, and failure modes. The post impact induced strains versus time responses were obtained for all slabs. The results showed that adding the polypropylene fiber at a dosage of 0.90% by volume of concrete leads to significant improvement in the overall structural behavior of the slabs and their resistance to impact loading. Interestingly, the enhancement in the behavior of the slabs using a higher fiber dosage of 1.2% was not as good as achieved with 0.90%.