• Journal of the Korea Society for Simulation
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• v.32 no.4
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• pp.1-10
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• 2023

This study examines the response when the shock by underwater explosion is transmitted to a vertical launch air-vehicle mounted on a ship using modeling and simulation, and is about a plan to increase method shock resistance to protect the air vehicle. In order to obtain an accurate mathematical model, a dynamic characteristic test was performed on similar equipment, and through this, the mathematical model could be supplemented. And, using the supplemented mathematical model, the air vehicle simulated the shock response by the underwater explosion specified in the BV043 standard. As a result of the first simulation, it was confirmed that air vehicle could not withstand shock, and air vehicle protection method using a ring spring type shock absorber was studied. In addition to the basic shape of abosber, it was confirmed that the ring spring absober can be used to increase the impact resistance of a shipborn vertical launch vehicle by performing simulations for each case by changing deseign varables.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.8
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• pp.1113-1118
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• 2010

It is requested that the interior compartment of a passenger vehicle must be satisfied with the FMVSS201U regulation, FMH impact test. It is needed the design methodology to find the appropriate structure about the FMH impact. When designing the impact-absorbing structure for the FMH impact test, it is to be noted that the impact absorber must have different performance considering the stiffness of the vehicle as the impact position and approach angle of FMH. In this study, an efficient design methodology was developed by using subcomponent collapse simulation instead of conducting full-vehicle simulation, thereby reducing the time and resources spent. Further, this unit-model simulation helps optimize the impact absorbing structure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.3
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• pp.399-407
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• 2022

Energy absorption facilities installed on roads should follow the performance standards of the real-car crash test of 'Installation and Maintenance Guidelines for Roadside Safety Facilities'. However, due to different installation conditions, such as differing structure widths on roads, some energy absorption facilities do not provide adequate performance. In order to apply varied environments on roads, an energy absorption structure was designed in this study with 150 mm height and four layers of W-shape guardrail at 200 mm intervals, and the performance was verified using LS-DYNA computer simulation. Through a real-car crash test, the performance of the facility designed by LS-DYNA was tested and was found to meet the performance of the CC2 category for crash cushions. The conclusion of the comparison demonstrates that the simulation and the real-car crash tests are both significant.

• Composites Research
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• v.22 no.6
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• pp.18-22
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• 2009

In this paper, we examined impact force and impact behavior through low velocity impact tests of composite laminates. And through c-scan as nondestructive inspection, explored the damaged area being difficult to examine with the visual inspection. Through CAI tests, we also measured the compression strength of composite laminates subjected to low velocity impact. To examine the characteristics of impact behavior measured from low velocity impact test, nondestructive inspection, and CAI test, the simulated data are generated from the test data using Monte-Carlo simulation, then represented it by probability distribution. The testing results using visible stochastic distribution were examined and compared.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1569-1575
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• 2012

In this study, ballistic impact effects on a helmet were investigated using the AUTODYN-3D program. Two types of materials were used for manufacturing the helmet: single Kevlar and Steel/Kevlar hybrid composites. Furthermore, two types of bullets were used in the simulation: steel spherical and 7.62 mm full-jacketed. In the simulation, the shape deformation of the projectile and internal energy were calculated. From the results, impact velocities above 655 m/s and 845 m/s were required to perforate the Steel/Kevlar helmet with steel spherical and 7.62 mm full-jacketed bullets, respectively. The results show that there was a large difference between the ballistic resistance of the Kevlar and Steel/Kevlar helmets. For the simulation on an NIJ-STD-0106.01 Type II helmet, a 7.62 mm fulljacketed bullet with a striking velocity of 358 m/s was used. Simulation results show that the Steel/Kevlar helmet could resist a 7.62 mm full-jacketed bullet traveling at 358 m/s.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.2
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• pp.23-30
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• 2009

Crash cushions are protective devices that prevent errant vehicles from impacting on fixed objects. This function is accomplished by gradually decelerating a vehicle to a safe stop in a relatively short distance. Commonly used crash cushions generally employ one of two concepts to accomplish this function. The first concept involves the absorption of the kinetic energy of a moving vehicle by crushable or plastically deformable materials and the other one involves the transfer of the momentum of a moving vehicle to an expendable mass of material located in the vehicle's path. Crash cushions using the first concept are generally referred to as compression crash cushions and crash cushions using the other concept are generally referred to as inertial crash cushion. The objective of this research is the development of a compression-type crash cushion by employing the two concepts simultaneously. To minimize the number of full-scale crash tests for the development of the crash cushion, preliminary design guide considering inertial and frictional energy absorption was constructed and computer simulation was performed. LS-DYNA program, which is most widely used to analyze roadside safety features, was used for the computer simulation. The developed crash cushion satisfied the safety evaluation criteria for various impact conditions of CC2 performance level in the Korean design guide.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.287-291
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• 2015

본 연구에서는 두 지역의 실제 상수관망에 대해서 부정류해석을 수행하였고 각각의 상수관망에 필요한 부정류피해 최소화방안을 제시하였다. 첫 번째 대상지역은 베트남 호치민으로 148개 절점과 162개의 파이프로 이루어진 소블럭 상수관망이며 두 번째 대상지역은 파주시 광탄면으로 512개 절점과 527개의 파이프로 이루어진 세 개의 소블럭 상수관망이다. 두지역의 상수관망은 지형적면이나 규모면에서 다른 모습을 하고 있기 때문에 부정류해석 시 발생가능한 피해유형이 틀린 것으로 나타났다. 호치민의 경우 배수지의 높이가 낮고 도시 내 표고차가 없어서 관망 내 평균수압이 $1kg/cm^2$을 약간 상회하는 수준으로 수압이 낮고 수압차 역시 작다. 따라서 상수관망에서 일어날 수 있는 소요수량의 변화나 소화전 사용과 같은 작은 변화에도 역류발생이 빈번히 일어나는 것으로 나타났으며 역류발생이 잦은 파이프를 선정할 수 있었다. 상당히 많은 파이프에서 단기간 역류가 발생하는 것을 확인할 수 있었다. 짧은 기간에 발생하는 변화에 대한 단기간 역류는 교차연결(Cross-Connection)의 문제를 야기할 수 있다. 따라서 역류발생이 빈번히 일어나는 파이프 주위에 check valve나 역지밸브등의 설치를 통해 역류로 인한 피해를 최소화할 수 있다. 파주시 광탄면 지역의 소블럭 집합으로써 고저차가 많은 지역이다. 배수지 밸브개폐 시 발생 가능한 수충격에 대한 시뮬레이션과 펌프장정지로 인해 발생할 수 있는 수충격에 발생 시뮬레이션을 수행하였고 관망내에서 자주 발생하는 밸브개폐로 인한 시뮬레이션을 수행하였다. 그 결과 광탄의 경우 수충격 발생위험 지점은 배수지 근처로 나타났고 수격압이 최대 $2.5kg/cm^2$에서 $3.0kg/cm^2$까지 발생 가능한 것으로 나타났고 밸브개폐시간이 1-2초 지연되어도 상당히 큰 수격압을 줄일 수 있는 것으로 나타났다. 수충격압이 크게 발생할 수 있는 지역에 수충격피해 최소화를 위해 surge tank와 같은 장치를 설치해야 한다. 또한 발생가능한 수격압의 크기를 통계적기법을 통해 확률밀도함수로 나타낼 수 있었다. 이 결과는 앞으로 상수관망의 설계나 운영에서 수충격피해 방지 장치 및 설비를 시공할 때 장치의 규모나 용량을 결정할 때 유용한 정보가 될 것으로 판단된다.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.5
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• pp.15-21
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• 1993

본 연구에서는 자동차 차체의 경량화 방안으로서 섬유강화 복합재료를 이용한 충격흡ㅅ수 구조재인 Side Member(측면부재)의 응용을 위한 시뮬레이션용 Box Tube의 충돌에너지 흡수특성 및 거동에 대해서 기존 금속 측면부재와 비교하여 논의해 보고자 한다. 1. 금속 충돌흡수 부재의 붕괴거동. 2. 복합재료 충격흡수부재의 붕괴거동.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.421-426
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• 2007

This study was analyzed dynamically by finite element method about the results of experiments which the double cantilever beam specimens with two kinds of materials were applied by impact load. And they were compared with each other as the simulation data applied onto impact velocities of 6.4 and 18.47 m/s. The crack energy release rate, force and displacement of block were calculated numerically by computer. As the numerical simulation data of specimen analyzed in this study approached the experimental data, the inspection of this specimen model suggested in this paper could be reasonable for the numerical simulation.

• Journal of the Korea Society for Simulation
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• v.30 no.3
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• pp.31-39
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• 2021

During artillery fire, an excessive level of impulse noise propagating in the form of a storm wave is generated. Since the sound of impact from the fire affects the stability of the surrounding structures, the artillery and the structures must be separated from each other by the proper distance to avoid damages from friendly fire. However, if they have already been built within the distance, it is possible to prevent the damages by building sound barriers between them. In this study, the proper separation distance between the artillery and the structure was calculated, and the insertion losses due to various heights and shapes of the sound barrier were simulated by using the BEM(Boundary Element Method), and conclusively the optimal sound barrier was selected.