• Explosives and Blasting
• /
• v.41 no.3
• /
• pp.1-12
• /
• 2023

A basic assessment of techniques to mitigate the risk of blast shock waves from proximity explosions was conducted. Common existing techniques include using mitigant materials to form barriers around the explosive or in the direction of propagation of the shock wave. Various explosive energy dissipation mechanisms have been proposed, and research on blast shock wave mitigation utilizing impedance differences has drawn considerable interest. In this study, shear thickening fluid (STF) was applied as a blast mitigation material to evaluate the effectiveness of STF mitigation material on explosion shock wave mitigation through explosion experiments and numerical analysis. As a result, the effectiveness of the STF mitigant material in reducing the explosion shock pressure was verified.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.20 no.1
• /
• pp.8-13
• /
• 2016

The purpose of the pyro-shock compliant joint is to isolated vibration using the compliant material in order to prevent the shock generated by pyro propulsion at the electronics equipment. The performance of the pyro-shock compliant joint can be determined by measuring bending natural frequency and transmissibility. In this study, we established the design requirements based on bending natural frequency and transmissibility results of the reference model. We developed a compliant material with sufficient shock compliant properties and a pyro-shock compliant joint for the new rocket. This results can be used to develop a pyro-shock compliant joint for any rocket using the compliant material and performance measurement.

• Proceedings of the KIEE Conference
• /
• 2006.07d
• /
• pp.2025-2026
• /
• 2006

충격 잡음은 전력선 통신 시스템의 성능을 열하시키는 대표적인 채널 특성 중 하나이다. 이는 배경잡음에 비해 많게는 수십 dB 이상의 레벨을 가지며, 임의 시간적으로 발생하기 때문에 추정 및 제어가 어렵다. 최근 전력선 통신 시스템이 고속화 되면서 한정된 주파수 대역상에서 한정된 신호 전력으로 대용량의 데이터를 전송하기 위해서 대역효율을 높이기 위한 변복조 기법과 오류정정 코드가 적용되고 있으나, 충격 잡음에 의해서 그 성능이 현저하게 열하된다. 일반적으로 충격잡음은 수신단에서 레벨 제한에 의해 그 영향 정도를 줄일 수 있다. 본 논문에서는 전력선 통신 시스템의 성능 향상을 위해 제안되고 있는 LDPC 부호화 OFDM 시스템에 대해 충격 잡음 수신 레벨 제한에 의한 성능 열하의 완화 정도에 대해 연구하였으며, 시뮬레이션을 통해 최적 성능을 위한 수신 레벨 제한 지표를 제시하였다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.30 no.3 s.246
• /
• pp.241-248
• /
• 2006

Shoe cushioning systems are important to prevent body injuries. This study developed and evaluated a cushioning system to reduce impact force on the heel. The cushioning system suggested consist of a polyurethane pocket, which contains water and porous grains of open cell to dissipate the energy effectively. Load-displacement curves fer the shoe cushioning system were obtained from an instrumented testing machine and the results were compared with various pockets with air, water or grains. Mechanical testings showed that the pocket with 5g porous grain was the best for the cushioning system. This system can be applied to the design of various kind of sport shoes.

• Transactions of The Korea Fluid Power Systems Society
• /
• v.2 no.2
• /
• pp.14-20
• /
• 2005

This study developed and evaluated a shoe cushioning system to reduce impact force patterns during running. The shoe cushioning system is composed with a poly urethane pocket, which contains water and porous grains to absorb the force against the weight inside the pocket. Load-displacement curves for the shoe cushioning system were obtained from an instrumented testing machine and the results were compared with various pockets that have air, water or grains. Mechanical testings showed that the pocket with 5 g particles was the best for the shoe cushioning system. This founding will be helpful to designing the shoe.

• Proceedings of the Safety Management and Science Conference
• /
• 2011.11a
• /
• pp.93-99
• /
• 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 of Precision Engineering Conference
• /
• 2010.11a
• /
• pp.921-922
• /
• 2010

• Composites Research
• /
• v.37 no.1
• /
• pp.21-31
• /
• 2024

This review paper investigates the use of shockwave attenuating materials within composite structures to enhance personnel protection against blast-induced traumatic brain injury (bTBI). This paper also introduces experimental methodologies exploited in the generation and measurement of shockwaves to evaluate the performance of the shock dissipating composites. The generation of shockwaves is elucidated through diverse approaches such as high-energy explosives, shock tubes, lasers, and laser-flyer techniques. Evaluation of shockwave propagation and attenuation involves the utilization of cutting-edge techniques, including piezoelectric, interferometer, electromagnetic induction, and streak camera methods. This paper investigates phase-separated materials, including polyurea and ionic liquids, and provides insight into composite structures in the quest for shockwave pressure attenuation. By synthesizing and analyzing the findings from these experimental approaches, this review aims to contribute valuable insights to the advancement of protective measures against blast-induced traumatic brain injuries.

• Journal of Biomedical Engineering Research
• /
• v.24 no.1
• /
• pp.31-36
• /
• 2003

Impact characteristics of six DM(Diabetes Mellitus) shoe insole materials (Podian, Plastazote black, Plastazote white, Flexible PU foam, Podialene 200 blue and Podia flex) and three multi-density insoles (AP, OS and PW insoles) were determined in the present study, using a self-designed impact measurement system. The coefficient of restitution, the median frequency and the attenuation index were calculated for each material, based on impact forces and linear accelerations. Podian revealed the superiority in the coefficient of restitution and the attenuation index. The median frequency of the Flexible PU foam was the smallest. Results also showed that the heel region was the most impact-attenuated among other areas in the insole. OS insole showed the better characteristics in the coefficient of restitution and the median frequency. but there was no significant difference in the attenuation index. Similar impact characteristics were found in all areas in PW insole. since it was basically of the same dual-density polyurethane.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1998.05b
• /
• pp.363-368
• /
• 1998

고리 1호기 주요기기들에 대한 수면평가 과정에서 원자로 압력용기의 중성자 조사취화에대한 잔여수명평가를 정량적으로 수행하였다. 그 결과 가압열충격 기준온도(R $T_{PTS}$)가 운전년수 34년경에 심사기준온도를 초과할 것으로 예측되어 연장운전 추진 시 선결되어야 할 과제로 인식되었다. 이에 따라 USNRC 가압열충격 규제지침서에 의한 상세 가압열충격 평가연구를 수행하고 있다. 본 논문에서는 원자로 압력용기 가압열충격 현상에 대해 간략히 설명하고 가압열충격 평가의 목적과 방법에 대하여 소개하였다. 더불어 현재 수행중인 고리 1호기 원자로 압력용기 가압열충격 평가의 일부로 수행한 계통 열수력해석과 확률론적 파괴역학 해석의 결과를 제시하고 가압열충격 위험도를 완화하기 위한 조치사항들에 대하여 검토하였다.다.