• 대한조선학회논문집
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• 제57권5호
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• pp.271-277
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• 2020

Recoverability and vulnerability of navy ships under underwater explosion are critical verification factors in the acquisition phase of navy ships. This paper aims to establish numerical analysis techniques for the underwater explosion of navy ships. Doubly Asymptotic Approach (DAA) Equation of Motion (EOM) of primary shock wave and secondary bubble pulse proposed by Geers-Hunter was introduced. Assuming a non-compressive fluid, reference solution of the DAA EOM of Geers-Hunter using Runge-Kutta method was derived for the secondary bubble pulse phase with an assumed charge conditions. Convergence analyses to determine fluid element size were performed, suggesting that the minimum fluid element size for underwater explosion analysis was 0.1 m. The spherical and cylindrical fluid domains were found to be appropriate for the underwater explosion analyses from the fluid domain shape study. Because the element size of 0.1 m was too small to be applied to the actual navy ships, a very slender beam with the square solid section was selected for the study of fluid domain existence effect. The two underwater explosion models with/without fluid domain provided very similar results in terms of the displacement and stress processes.

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 2002년도 추계학술발표대회 논문개요집
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• pp.69-72
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• 2002

• Advances in Computational Design
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• 제1권4호
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• pp.357-370
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• 2016

This paper aims to examine the dynamic response of a newly designed ultrasonic motor under half-sine shock impulses. Impact shock was applied to the motor along x, y or z axis respectively with different pulse widths to check the sensitivity of the motor to the shocks in different directions. Finite Element Analysis (FEA) with the ANSYS software was conducted to obtain the relative displacement of a key point of the motor. Numerical results show that the maximum relative displacement is of micro meter level and the maximum stress is five orders smaller than the Young's modulus of the piezo material, which proves the robustness of the motor.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.313-314
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• 2016

본 논문에서는 리튬이온(Li-Ion) 배터리 셀(Cell)의 Shock test와 Vibration test 기반 18650 원통형 셀 내부 전기적 특성 변화를 분석하였다. 전류적산법을 기반으로 방전 용량을 측정하였고, OCV(Open Circuit Voltage) 측정 및 HPPC(Hybrid Pulse Power Characterization) test를 기반으로 내부 저항을 측정하고 진동 및 충격 시험 전 후의 파라미터를 비교 분석하였다.

• 한국군사과학기술학회지
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• 제20권5호
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• pp.608-619
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• 2017

In this paper, the effects of parameters related to the residual stress induced due to laser shock peening process to determine mitigation of the initial tensile residual stresses are discussed, such as the maximum pressure, pressure pulse duration, laser spot size and number of laser shots. In order to estimate the influence of the initial tensile residual stresses, which is generated by welding in 35CD4 50HRC steel alloy, the initial condition option was employed in the finite element code. It is found that $2{\times}HEL$ maximum pressure and a certain range of the pressure pulse duration time can produce maximum mitigation effects near the surface and depth, regardless of the magnitudes of tensile residual stess. But plastically affected depth increase with increasing maximum pressure and pressure pulse duration time. For the laser spot size, maximum compressive residual stresses have almost constant values. But LSP is more effective with increasing the magnitudes of tensile residual stress. For the multiple LSP, magnitudes of compressive residual stresses and plastically affected depths are found to increase with increasing number of laser shots, but the effect is less pronounced for more laser shots. And to conclude, even though the initial tensile residual stresses such as weld residual stress field are existed, LSP is enough to make the surface and depth reinforcement effects.

• 한국소음진동공학회논문집
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• 제12권7호
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• pp.510-519
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• 2002

The present study addresses a computational work of the weak shock wave propagating inside an automobile exhaust muffler. Several different types of the silencer systems are employed to investigate the magnitude of the shock wave during propagating through them. The Initial shock wave Mach number $M_s$ is varied between 1.01 and 1.30, and a normal shock wave is given at the inlet of the silencer systems. The second order total variation diminishing scheme Is employed to solve the two dimensional, compressible, unsteady Euler equations. The present computational results are compared with the previous experimental ones available. The present computations predict the experimental results with a quite good accuracy. Of the four silencer systems applied. the most desirable silencer system to reduce the peak pressure at the exalt of the exhaust pipe is discussed from the Point of view of the engineering design of the silencer systems.

• 한국가시화정보학회지
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• 제22권1호
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• pp.18-27
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• 2024

A series of shock wave pulses with Mach number 2.2 of 100, 200, and 300 shocks were applied to lead sulfide (PbS) nanomaterials at intervals of 5 sec per shock pulse. To investigate the crystallographic, electronic, and magnetic phase stabilities, powder X-ray diffractometry (XRD), diffused reflectance spectroscopy (DRS), and vibrating-sample magnetometry (VSM) were employed. The material exhibited a rock salt structure (NaCl-type structure); XRD results indicated that material is monoclinic with space group C121 (5). Further, XRD results showed shifts due to lattice contraction and expansion when material was subjected to shock wave pulses, indicating stable material structure. Based on the data obtained, we believe that the PbS material is a good choice for high-pressure, high-temperature, and aerospace applications due to its superior shock resistance characteristics.

• 한국생산제조학회지
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• 제24권3호
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• pp.342-347
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• 2015

The launcher pod for missiles capable of carrying a range of different warheads has been designed to be mounted on the tracked vehicle of the hybrid weapon system (HWS). In the development of this launcher pod, its structure was designed to be resilient to damage caused by shock and vibration, as well as preventing assembly errors due to the spring-back of the main composite cover and interfacing parts. This study investigated the design of the newly developed launcher pod, with its hybrid composite-metal structure, through simulation and experiment. Both simulation and actual experiments showed that the structure of the launcher is resilient to vibration and shock. The launcher pod was also subjected to vibration and shock tests to verify its performance.

• 한국음향학회지
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• 제39권4호
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• pp.303-317
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• 2020

체외충격파치료술(Extracorporeal Shock Wave Therapy, ESWT)은 보존적인 치료가 어려운 근골격계 난치성 통증 치료 뿐 아니라 심혈관계 질환까지 적용 분야가 확대되고 있는 혁신적인 치료술이다. 본 연구에서는 국내에서 사용되는 집속형 ESWT 치료기의 성능을 결정하는 충격파 음향 출력의 분포를 조사했다. 분석에 사용된 데이터는 식약처에 등록된 30개 기술 문서를 통해 수집했다. 조사 결과, ESWT 치료기 충격파의 집속 특성은, 초점 거리가 5 mm ~ 65 mm, 초점 폭이 3 mm ~ 30 mm, 초점 깊이가 4 mm ~ 108 mm 범위에서 변화하고 있다. 충격파의 최대 양압(P+)는 7 MPa ~ 280 MPa, 초점에서 에너지 밀도 Energy Flux Density(EFD)는 0.0035 mJ/㎟ ~ 35 mJ/㎟, 펄스당 에너지(E)는 0.737 mJ ~ 80.86 mJ로 매우 넓은 범위에서 분포하고 있다. P+ 및 EFD 상관성 분석에 포함된 모든 국내산 PE 방식 제품(5개) 및 1개의 EM 방식 국산 치료기는 P+ 및 EFD가 통상적인 범위를 크게 벗어나고 있으며, 예상되는 상관성을 따르지 않고 있어, 데이터의 신뢰성을 인정하기 어려운 상태이다. 음향 출력의 값에 신뢰성을 부여하기 어려운 경우, 식약처에서 인정하는 시험 검사 기관을 통해 사후 시험 검사 및 관리가 요구된다. 충격파 음향 출력에 대한 통과 기준이 치료기의 적응증에 대한 임상 시험 결과를 근거로 설정될 수 있도록 식약처의 규정 및 가이드라인 개선이 필요하다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.383-384
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• 2016

본 논문에서 shock test를 적용한 고출력 리튬이온 원통형 셀의 내부 전기화학적 특성을 비교하였다. 용량이 동일한 고출력 리튬이온 원통형 셀을 사용하여 shock test를 적용하였다. 충격 전후에 OCV (Open Circuit Voltage) 및 HPPC (Hybrid Pulse Power Characterization) 테스트 기반 방전용량 및 내부저항을 측정하였으며 이를 통해 각 고출력 리튬이온 원통형 셀의 일정한 변화율을 확보하였다.