• Proceedings of the Safety Management and Science Conference
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• 2011.11a
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• pp.93-99
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• 2011

안전모는 낙하, 비례물에 대한 두부를 보호하는 보호구로 낙하물의 충격을 일부 흡수하여 완화시켜주는 기능을 하고 있다. 안전모 충격 흡수 성능으로 최고전달충격력이 있으나 낮을수록 성능이 좋은 것으로 나타나지만 안전모 제조과정에서 얼마 만큼의 충격이 흡수되는지는 알 수 없었다. 이로 인하여 성능 향상을 위한 충격력의 명확한 제어 가능한 성능 향상의 기준을 잡는데 어려움이 있었다. 본 연구에서는 충격량과 연관된 반발계수로 충격흡수 성능의 정도를 찾고자 하였다. 연구 대상은 시중에서 주로 착용되고 있는 ABS 재질의 안전인증 합격품을 대상으로 선정 하였다. 연구 방법으로는 운동량과 충격량의 이론으로 안전모 충격흡수성능 시험장치를 활용하여 인두에 전달된 충격량을 활용하여 충격흡수시의 반발계수를 구하고, 충격을 흡수치 않을 때를 가정하여 추정 충격력 곡선을 유도하고 충격흡수 전의 추정 최고 전달충격력과 반발계수를 구하여 충격흡수의 성능을 나타내었다. 연구결과 국내 안전인증 H사의 안전모의 최고전달충격력은 4100 N 이였고, 충격흡수 성능은 400 N 으로 약 9 %를 흡수되는 것으로 나타났다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.191-195
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• 2003

충격음 저감재의 동탄성계수와 감쇠계수는 차단성능을 평가하는데 있어 중요한 물성치가 된다. 저감재의 동탄성계수는 뜬바닥구조의 고유진동수를 결정짓게 되며, 저감재의 동탄성계수가 높을수록, 즉 고유진동수가 높아짐에 따라 실험실 경량충격음레벨 저감량은 지수함수적으로 감소됨을 실험을 통해 알 수 있다. 또한, 저감재를 포함한 뜬바닥구조를 1자유도 진동계로 가정한 이론값과 실험실 경량충격음레벨 저감량의 결과가 비교적 잘 일치하는 것으로 나타났으며, 이 때 감쇠계수의 영향은 반드시 고려되어야 한다.

• Journal of Digital Convergence
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• v.15 no.7
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• pp.223-229
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• 2017

Europe, the US and Japan have acquired test results on impact coefficient for a long time and applied it to equipment design to secure safety of structures. However, Korean enterprises use the impact factor held by advanced business to design equipment as it is difficult for them to obtain it through tests. In this paper, NX/NASTRAN, was used to perform static load analysis and impact load analysis of a PCB Handler, semiconductor test equipment, and the result was employed to study how to calculate the impact coefficient with the finite element analysis. The calculation method was applied to the JIS(Japanese Industrial Standard), and the impact coefficient of the PCB handler was calculated as 1.27 for the sudden start or stop. The impact coefficient generated by the analysis is expected to make a great contribution to the industry as it can be used to improve the equipment structure and develop on existing equipment in the future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.70-76
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• 2013

The objective of the paper is to present the results of analytical and experimental studies dealing with dynamic load for continuous steel girder bridges due to normal truck traffic. Various bridge design codes specify dynamic load factor (defined as a fraction of static portion of live load) for short span structures at the level of about 0.3. However, there are not definite values specified for continuous brigdes. Therefore, it is an usual practice to use the code specified dynamic load factors for simple span bridges to continuous bridges without clear background. The field measurement results indicate that the actual dynamic load factors are less than 0.2 for a single truck, and less than 0.05 for two trucks side-by-side, regardless of positive and negative moment region.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.105-113
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• 2018

The proposed model to predict the bridge load carrying capacity uses the impact response spectrum. The spectrum is based on Euler-Bernoulli beam and the center of the bridge width for the moving load location. Therefore, it is necessary to investigate the eccentric moving load effects on the impact factor and response factor. For this, this study considers 10 m width and two-lane simply supported slab bridges and performs the moving load analysis to investigate the variations of peak impact factor and corresponding response factor. The numerical results show that the eccentric load increases both the static and dynamic displacements, but the impact factor is decreased since the incremental amount of static displacement is bigger than that of dynamic displacement. However, the difference of the impact factors between the center and eccentric loadings is small showing less than 0.5%p. In the response factor, the eccentric loading increases both the static and dynamic response factors, compared to the center loading. The difference of the response factor is only 0.18%p. It shows that the eccentric loading has very small effects on the response factor, thus the impact factor response spectrum which is generated based on the center moving load can be used to determine the response factor.

• Computational Structural Engineering
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• v.5 no.3
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• pp.139-146
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• 1992

Vibrational behaviors of highway girder bridges due to heavy traffics are discussed, and empirical formulae for impact factors are suggested in this paper. Appropriate vehicle model for vibration analysis is found and impact factors are calculated with different surface roughnesses, vehicle speeds and span lengths. It is shown that the present codes tend to underestimate impact factors.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.374-377
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• 2002

폐공을 이용한 도심지역 지하수 환경 복원 및 음용화 기술개발 연구의 한 과정으로 보은지역의 지하수계를 이해하고 지하수 개념모델을 설정하기 위한 단계로 보은지역 화강암의 수리적 특성을 파악하고자 순간충격시험을 실시하였다. 순간충격시험은 경제적 수리상수 산출을 위한 현장시험방법으로서, 이를 통해 수리전도도, 특수량계수 그리고 저류계수를 산출하였다. 그리고 dummy의 주입과 인양시 다르게 나타나는 수리전도도값의 원인에 대해서도 고찰해 보았다

• Computational Structural Engineering
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• v.5 no.2
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• pp.87-91
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• 1992

Vibrational behaviors of highway girder bridges due to heavy traffics are discussed, and empirical formulae for impact factors are suggested in this paper. Appropriate vehicle model for vibration analysis is found and impact factors are calculated with different surface roughnesses, vehicle speeds and span lengths. It is shown that the present codes tend to underestimate impact factors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.301-306
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• 2016

In bridge performance assessments, a new load carrying capacity evaluation model of simple bridges was proposed, which is based on the developed simple support impact factor spectrum. In this paper, a conservative assumption that the inner span with the both ends fixed boundary condition is ideal for applying the impact factor response spectrum for continuous bridges. The impact factor response spectrum has been proposed based on this assumption. The response spectrum by comparing the numerical analysis result and actual measurement data verified the applicability. The analysis was loading the moving load of DB-24 in a six-span continuous bridge, which was the same as the actual measurement data, the dynamic response was measured in the fourth span. The frequency of the bridge was obtained by FFT on the acceleration response and the span-frequency of sample bridge was calculated by the frequency. The impact factor of the sample bridge was determined by applying the span-frequency of the bridge to the proposed response spectrum; it was similar to the result of comparing the actual measured impact factor. Therefore, the method using the impact factor response spectrum based on the frequency response of both ends-fixed beam was found to be applicable to an actual continuous bridge.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.570-573
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• 2003

광산개발로 인한 지하수 유동체계 변형에 따른 주변환경 영향조사의 과정으로 충북 음성군 지역에서 야외 조사를 실시하였다. 조사 과정중 연구지역의 지하수계를 이해하고 개발에 따른 지하수 유동체계 변화를 예측하고자 수행된 모델링의 입력인자 산정을 위해 순간충격시험을 실시하였다. 순간충격시험을 통해 수리전도도, 투수량계수 그리고 저류계수를 산출하였다. 그리고 dummy의 주입과 회수시 다르게 나타나는 수리전도도값의 원인에 대해서도 고찰해 보았다.