• 대한기계학회논문집A
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• 제22권4호
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• pp.826-833
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• 1998

The energy-absorbing characteristic of impact limiters affects the cask design so significantly that it should be evaluated as accurate as possible. The objective of this study is to find the influence of the impact limiter's steel case and gusset plates which enclose the shock absorbing cellular material on the impact energy absorption. The influence of impact limiter's steel case and gusset plate stiffeners on the impact energy absorption behavior under horizontal drop impact was evaluated for a radioactive isotope transport cask. Though the impact limiters mitigate the impact damage of the cask, the impact limiter's steel case and gusset plate stiffeners increase the impact force so significantly that should be designed as soft as possible. The impact analysis without considering impact limiter's steel case and gusset plates stiffener gives non-conservative results, so the stiffness of the steel case and gusset plates should be considered in impact analysis.

• Computers and Concrete
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• 제26권3호
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• pp.275-283
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• 2020

Reinforced concrete (RC) does not provide sufficient resistance against impacts and blast loads, and the brittle structure of RC fails to protect against fractures due to the lack of shock absorption. Investigations on improving its resistance against explosion and impact have been actively conducted on high-performance fiber-reinforced cementitious composites (HPFRCCs), such as fiber-reinforced concrete and ultra-high-performance concrete. For these HPFRCCs, however, tensile strength and toughness are still significantly lower compared to compressive strength due to their limited fiber volume fraction. Therefore, in this study, the tensile behavior of slurry-infiltrated fiber-reinforced cementitious composites (SIFRCCs), which can accommodate a large number of steel fibers, was analyzed under static and dynamic loading to improve the shortcomings of RC and to enhance its explosion and impact resistance. The fiber volume fractions of SIFRCCs were set to 4%, 5%, and 6%, and three strain rate levels (maximum strain rate: 250 s^-1) were applied. As a result, the tensile strength exceeded 15 MPa under static load, and the dynamic tensile strength reached a maximum of 40 MPa. In addition, tensile characteristics, such as tensile strength, deformation capacity, and energy absorption capacity, were improved as the fiber volume fraction and strain rate increased.

• 국제물리치료학회지
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• 제7권2호
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• pp.1037-1040
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• 2016

This study aims to investigate the effects of ankle foot orthosis(AFO) on the activities of tibialis anterior(TA), soleus(Sol), rectus femoris(RF) and biceps femoris(BF) during stairs descending. The activities of TA, Sol, RF and BF were initially measured while descending 4 stairs without using AFO. The activities of the same muscles were then measured again while descending 4 stairs while using AFO. Wilcoxon signed-rank tests were used to analyze the results in order to examine the differences between the with using AFO and without using AFO. Although the activities of TA, Sol and RF were relatively lower while using AFO than without using AFO, only the differences in Sol and RF activities were significant(p<0.05). The activity of BF was relatively higher while using AFO compared to the activity of BF observed without using AFO. However, difference was not significant(p>0.05). Conclusion of this study was observed since AFO's ground reaction force absorption during stairs descending reduced the need to use So and RF that is related to shock absorption. BF activity was increased with AFO than without during standing forward to correct the trunk stability.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.323-328
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• 2002

The 1995 devastating Hyogoken-Nambu earthquake sent mental shock waves that awakened the public concern about the seismic performance of infrastructures in Korea. Seismic safety of reinforced concrete bridge piers could be secured through sufficient strength and stiffness of longitudinal steels and confined core concrete, and through ductile behaviour of bridge piers in the inelastic range. This study has been performed to verify the effect of lap spliced longitudinal steel for the seismic behavior of reinforced concrete bridge piers. Quasi-static test has been done to investigate the physical seismic performance of RC bridge piers, such as displacement ductility, energy absorption etc.

• 한국정밀공학회지
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• 제26권5호
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• pp.128-134
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• 2009

This paper aims to design a variable-stiffness type economical safety joint for service robots. The safety joint was designed to have a passive shock absorbing mechanism for protecting human from a catastrophic collision under service condition of robots. A simple mechanism composed of two action disks for switching the load transfer, a spring and a screw for pre-load was proposed. In order to evaluate the performance of the safety joint a testing platform which can carry out the static and impact tests was also designed and fabricated. From the test results, the designed safety joint was proved to have a variable load-carrying capacity and about 42% impact absorption capacity with simple manipulation of the control screw.

• East Asian Economic Review
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• 제24권1호
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• pp.89-124
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• 2020

Even with the sizable Foreign Exchange (FX) holdings and good credit ratings of its top assets, Asia remains vulnerable to various shocks. This paper highlights the limited cross-border asset pledgeability as a significant factor for the lingering vulnerability in Asia. The dichotomy in asset holdings between pledgeable FX and non-pledgeable domestic assets in major economies in Asia has been the source of increasing stabilization costs as well as weakened market momentum in the region. Specifically, the peculiar feature of asset holdings in Asia reflects seriously deficient cross-border asset pledgeability that is left unaddressed. Asset pledgeability contributes toward financial stability via three channels: 1) capital market development by recognizing the role of collateral, 2) increased shock absorption capacity via collateral management, 3) and the newly activated safe asset provision. Therefore, it is crucial to go beyond the usual market development strategy and expand the overall asset pledgeability in the region that has remained unduly depressed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.933-938
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• 2007

These days, up-to-date humanoid robots are continuously developed. Among them, Qrio, Asimo[1,2] are famous for its unique walking technology and natural movement. These robots could show manufacturers' technological improvement and leave a good impression to the customer. In accordance with global trends, Samsung is also producing humanoid robot. The humanoid robot, however, could walk like a human compared to the industrial robot fixed in the factory. This feature could cause another dynamic effect while walking. In this paper, the robot's feet were examined to find out parameters that affect stability of the humanoid robot's feet. With the sensitivity analysis, the optimization procedure in design of experiments finds the most suitable performance of robot. Maximum deflection of the frame upon various cases was minimized, and rubber coefficients for shock absorption were optimized.

• 한국자동차공학회논문집
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• 제24권3호
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• pp.352-357
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• 2016

More recently, workers and passengers of casualties has increased by rear-end collisions of unexpected while working on the road. Recently attracted air chamber TMA mounting car accidents which occurred in 3 years, and analyzed the effect of reducing the shock absorption and protection performance and casualties. There is a risk of the vehicle AIS4 more injury of high five accidents of casualties risk, also, was the analysis that there is risk of death was avoided by the air chamber TMA and SGT. Therefore, by mounting the TMA in the rear-end accident, so you can reduce the death and casualties, it must be increased this of attach rate for road construction vehicle.

• 대한기계학회논문집A
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• 제29권9호
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• pp.1191-1198
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• 2005

This paper is concerned with the numerical investigation of the landing impact characteristics of sport shoes to the landing mode. In most court sport activities, jumping and landing are fundamental motions, and the landing motion is largely composed of forefoot and rearfoot landing modes. Since the landing impact may, but frequently, lead to unexpected injuries of players, the investigation of its characteristics and the sport shoes design for reducing it are of a great importance. To investigate the landing impact characteristics to the landing mode, we construct a shoes-leg coupled model and carry out the numerical simulation by an explicit finite element method.

• 한국지반환경공학회 논문집
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• 제15권11호
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• pp.53-59
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• 2014

낙석방지망에 대한 기존 연구 결과에 의하면 종래의 낙석방지망에서 발생되는 대표적인 문제점으로 이완성이 없는 횡방향 와이어로프에 의해 발생되는 낙석 중량의 누적현상, 지반과 낙석방지망의 결합지점 부족으로 인한 인발지지력 부족, 낙석의 과도한 충격으로 인한 철망의 빈번한 파손, 낙석방지망의 유지관리 시 철망의 재사용의 어려움 등이 보고되고 있다. 선행 연구를 통해 실내에서의 인장력과 현장실험이 실시되어 새로운 낙석방지망의 효과를 검증한 바 있다. 선행연구에 이어 본 연구에서는 기존의 사각낙석방지망과 비교하여 충격 완화형 육각 낙석방지망의 전체적인 구조적 안정성과 성능을 수치해석적 방법을 통해 점검하는 것에 그 목적이 있으며, 이를 충분히 검토하고 결과를 얻을 수 있도록 수치해석 프로그램이 설정되었다. 수치해석 결과를 종합해볼 때 동일한 단일 셀 간격 뿐만 아니라 동일한 면적비로 비교하더라도 육각 낙석방지망이 사각 낙석방지망에 비해 하중분배 효과가 우수한 것으로 나타났으며, 육각 낙석방지망은 낙석하중이 작용할 경우 이를 효율적으로 분산시킴으로써 과도한 하중 집중이 발생하는 것을 피할 수 있어 장기적인 안정성 확보에 유리할 것으로 판단된다.