• Computational Structural Engineering
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• v.10 no.4
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• pp.12-21
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• 1997

차량충돌에 대하여 운전자의 안전확보를 위하여 새로 개발한 철재 중앙분리대에 대한 안전성 분석을 위하여 인체모형을 탑재한 실물차량 충돌실험을 실시하였다. 인체모형의 두부와 흉부, 대퇴부 및 차량의 무게중심점에서 가속도와 충격하중을 계측하여 철재 중앙분리대 방호울타리에 차량충돌시 운전자의 안전성을 검증한 결과 다음과 같은 결론을 도출하였다. 1) 철재 중앙분리대 방호울타리는 콘크리트 중앙분리대 방호울타리에 비해 운전자의 신체 상해치와 차량파괴 등에 있어서 뛰어난 충격흡수성능을 보여주었다. 2) 철재 중앙분리대 방호울타리는 콘크리트 중앙분리대 방호울타리의 경우 빈번히 발생하는 차량전복과 같은 2차사고의 유발 가능성이 전혀 없는 구조적 안정성을 보여주었다. 3) 경량의 차량충돌에 대하여 자체 탄성영역내에서 충격을 흡수하여 유지보수 측면에서 유리함을 나타냈다. 4) 충돌 수 충돌차량에 대한 차량유도성능이 뛰어났으며, 차량의 충돌후 이탈각도는 충돌각도의 60% 이내로 나타났다. 5) 철재 중앙분리대 방호울타리로부터 분리된 파편이 거의 없어 도로소통에 지장을 초래하지 않는다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.92-93
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• 2013

In this study, Shock Absorption performance of Magneto-rheological elastomer(MRE) is identified through the drop impact test. Magneto-rheological materials are divided into two groups by MR fluid in fluid state and MR elastomer in solid state like rubber. The stiffness characteristics of Magneto-rheological material can be changed as magnetic field is applied. The impact loads in MR elastomer were measured under weight of impactor. Experiment results are shown through the experiments to confirm the effect of shock absorption of MR elastomer. Thus, the MR elastomer can be applied to shock absorber used in area that shock occurs.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.169-177
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• 2011

In this study, an impact resistance of concrete segmented composites adopted shell's structures which have the excellent impact resistance was assessed. In order to enhance the performances of concrete segmented composite, the bond strength of mortar between the concrete blocks should be improved. Hence, in this study polymer mortars were applied to increase the bond strength of mortar. From the results of bond tests, the 15% latex mortar was selected and static and low-velocity impact tests were carried out for the specimens applied the plain and latex mortar. The concrete segmented composites, of which the bond strength of mortar was enhanced, showed improved low-velocity impact resistances. A Nonlinear finite element analysis using the discrete crack model showed similar energy dissipating capacities to the impact test's results. Consequently, by improving the analysis models for segmented composites, the impact resistances for manifold variables can be predicted and assessed.

• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.3
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• pp.15-21
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• 2003

This experimental study describes the propagation characteristics of the impulse noise emitted from the exit of a perforated pipe attached to the open end of a simple shock tube facility. The pressure amplitudes and directivities of the impulse wave propagating outside from the exit of pipe with several different configurations are measured and analyzed for the range of the incident weak shock wave Mach number between 1.02 and 1.2. In the experiments. the impulse waves are visualized by a Schlieren optical system for the purpose of understanding their propagation characteristics. The results obtained show that for the near sound field the impulse noise strongly propagates toward the pipe axis, but for the far sound field the impulse noise uniformly propagates toward the omnidirections, indicating that the directivity pattern is almost same regardless of the pipe type. For this non-directivity in the far sound field, it is shown that the perforated pipe has little performance to suppress the impulse noise.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.267-270
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• 2007

Korea Aerospace Research Institute(KARI) made a scramjet engine test contract with the University of Queensland in October 2006. The experiments were conducted at Mach 7.6, Altitude 31.2 km condition in the T4 free piston-driven shock tunnel in June 2007. In this paper, the short introduction and data processing technique of the T4 free piston-driven shock tunnel will be explained.

• Proceedings of the Safety Management and Science Conference
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• 2013.11a
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• pp.539-546
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• 2013

본 연구는 승마용 안전모의 신뢰성 확보를 위해 안전기준을 정립하기 위한 연구이다. 국내 외 레저 스포츠 안전모 관련 안전기준을 비교 분석하여 도출한 주요 시험평가방법을 현재 국내에 유통 중인 중저가 승마용 안전모를 대상으로 성능시험을 하였다. 충격흡수성 시험 시 1축과 3축 가속도 센서를 이용한 시험방법에 대해서 성능평가 데이터를 통해 1축 가속도 센서를 이용한 충격흡수성 시험으로 선정하였다. 유지시스템의 강도시험에서 헤드 폼 서포트 방식과 후크 서포트 방식으로 구분되던 것을 시료에 손상 없이 시험 가능한 헤드 폼 서포트 방식으로 결정하였다. 이와 같이 승마용 안전모의 안전기준을 정립하여 제품의 안전성 및 신뢰성을 확보하고 나아가 "품질경영 및 공산품 안전 관리법"에 규정함으로써 자국민의 안전을 확보하고 중국산 저가 제품에 대한 시장진입장벽을 구축하여 경쟁력 있는 안전모 시장을 구축하기를 기대한다.

• Bulletin of the Society of Naval Architects of Korea
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• v.58 no.2
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• pp.27-29
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• 2021

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.12
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• pp.1025-1031
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• 2012

The present paper deals with concept design of supersonic inlet based on compressible flow theory and flow control of bleeding in order to guarantee stability of supersonic inlet of ramjet engine in broad range of operating conditions. Shock instability, shock wave-boundary layer interaction and flow separation should be properly controlled to improve performance of the supersonic inlet. Considering shock strength, boundary layer and flow separation, the supersonic inlet is modified from the basic model which is designed under inviscid theory. Consequently, shock is stabilized, and required mass flow rate is obtained. Furthermore, bleeding is applied to the supersonic inlet to maintain performance in off-design conditions. Mass flow condition is adopted for modeling of bleeding effect, and performance of the supersonic inlet is evaluated by changing bleeding locations and numbers.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.5
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• pp.80-87
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• 2017

The performance of a pyrotechnic device that consists of donor/acceptor pair separated by a bulkhead relies on shock attenuation characteristics of the gap material and shock sensitivity of the donor and acceptor explosives. In this research, a micro Kapton flyer was accelerated by an exploding foil initiator (EFI) to figure out shock sensitivity of hexanitrostilbene (HNS) to impact. The averaged shock pressure and duration imparted to the explosive by flyer impact are measured by using a velocity interferometer for any reflector (VISAR) and impedance matching technique. Consequently, this research shows the possibility to determine the critical flyer velocity for initiating the miniaturized pyrotechnic unit by determining the relations between the impact velocity, the amplitude and width of impact loading.

• 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.