• Title/Summary/Keyword: 수중 폭발

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NUMERICAL ANALYSIS ON THE REACTOR CORE EXPANSION AND ENERGY BEHAVIORS DURING CDA USING UNDERWATER EXPLOSION THEORY (수중폭발 이론을 사용한 노심폭주사고 시 노심 팽창 및 에너지 거동 수치해석)

  • Kang, S.H.
    • Journal of computational fluids engineering
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    • v.21 no.3
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    • pp.8-14
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    • 2016
  • A numerical analysis is conducted to estimate the core expansion and the energy behaviors induced by a core disruptive accident in a sodium-cooled fast reactor. The numerical formulation based on underwater explosion theory is carried out to simulate the core explosion inside the reactor vessel. The transient pressure, temperature and expansion of the core are examined by solving the equation of state and nonlinear governing equation of momentum conservation in one-dimensional spherical coordinates. The energy balance inside the computation domain is examined during the core expansion process. Heat transfer between the core and the sodium coolant, and the bubble rise during the expansion process are briefly investigated.

Whipping factor - a Measure of Damage Potential of an UNDEX Bubble Pulse (휘핑계수-수중폭발 가스구체 압력파 크기의 척도)

  • Kwon, Jeong-Il;Chung, Jung-Hoon;Lee, Sang-Gab
    • Journal of the Society of Naval Architects of Korea
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    • v.42 no.6 s.144
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    • pp.637-643
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    • 2005
  • A new novel Whipping Factor is proposed as a measure of the ship damage potential due to an underwater explosion bubble pulse. The factor was derived from the relationships among the charge weight, its depth and the fluid acceleration due to pulsating gas bubble. From the whipping response analyses for three uniform Timoshenko beams with similar characteristics of real naval surface ships, we have confirmed the maximum bending moment responses of beams due to whipping are almost same if the applied whipping factor is constant regardless of the charge weights and depths, which could validate the proposed whipping factor.

Measurement of the Impact Fuze Phenomena using the Underwater Explosion (수중폭발을 이용한 충격신관 작동 계측)

  • Choi, SiHong
    • Journal of the Korea Institute of Military Science and Technology
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    • v.17 no.4
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    • pp.479-484
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    • 2014
  • In this paper, This study shows the content on the impact fuze test and the measurement using underwater explosion phenomena. The impact fuze has both a delay function and a super quick. Up to now, nothing but the naked eye of the observer has been used to verify performance of the impact fuze. The observer has determined the performance by the shape of the plume created from the explosion phenomenon. However, it is extremely difficult to use that method at a long range. In order to solve the problem, the measurement using the underwater explosion phenomena was tried.

Structural Response and Reliability of a Cylindrical Array Sensor due to Underwater Explosion (수중폭발에 의한 원통형 배열센서의 구조 응답 및 안정성 해석)

  • Jeon, Soo-Hong;Hong, Chin-Suk;Jeong, Weui-Bong;Seo, Hee-Seon;Cho, Yo-Han
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.1
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    • pp.81-87
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    • 2012
  • This paper establishes a modeling and simulation procedure for structural response and reliability of a cylindrical array sensor on submarines under the shock generated by underwater explosion. The structural reliability of SONAR is important because the submarine could get out of combat ability by the structural damage of the SONAR upon explosion. A cylindrical array sensor was first modeled using the finite element method. Modal analysis was then performed for the check of the reliability of the modeling. The shock resistance simulations were performed for the responses to the structural shock waves and for the responses to the directly applied underwater shock waves, according to BV-043 and MIL-STD-901D, respectively. The stresses of the structure were evaluated with von-Mises scheme. Vulnerable regions were exposed through mapping the maximum stress to the structural model. Maximum stress of the SONAR was compared with the yield stress of the material to examine the structural reliability.

A Study on Actuation Probability of Underwater Weapon Based on Magnetic Field (Magnetic Field 기반 수중무기체계 발화확률에 관한 연구)

  • Lim, Byeong-Seon;Hong, Sung-Pyo;Kim, Young-Kil
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.5
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    • pp.1253-1258
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    • 2013
  • This Paper deals with detection and defense methods for underwater weapons because there are so many dangers of underwater weapons not only in the war period but also in the peace time. Underwater mines are the representative strategic arms. The sensors and target detection methods, threat elimination method of mines included in this paper. Among the various sensors of mine, we use the magnetometor for target detection method in the simulation and execute the analysis of magnetic field of detected target ships. It will be also provided that effectiveness of target detection, sweeping method of mine, tactics of mine planning and mine sweeping and so on.

A Study on Inelastic Whipping Responses in a Navy Ship by Underwater Explosion (수중 폭발에 의한 함체의 비탄성 휘핑 응답에 관한 연구)

  • Kim, Hyunwoo;Seo, Jae Hoon;Choung, Joonmo
    • Journal of the Society of Naval Architects of Korea
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    • v.58 no.6
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    • pp.400-406
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    • 2021
  • The primary effect of the far-field underwater explosion (UNDEX) is the whipping of the ship hull girder. This paper aims to verify why inelastic effects should be considered in the whipping response estimations from the UNDEX simulations. A navy ship was modeled using Timoshenko beam elements over the ship length uniformly keeping the constant midship section modulus. The transient UNDEX pressure was produced using two types of the Geers-Hunter doubly-asymptotic models: compressible and incompressible fluids. Because the UNDEX model based on incompressible fluid assumption provided more increased fluid volume acceleration in the bubble phase, the incompressible fluid-based UNDEX model was adopted for the inelastic whipping response analyses. The non-linear hull girder bending moment-curvature curve was used to embed inelastic effects in the UNDEX analyses where the Smith method was applied to derive the non-linear stiffness. We assumed two stand-off distances to see more apparent inelastic effects: 40.5 m and 35.5 m. In the case of the 35.5 m stand-off distance, there was a statistically significant inelastic effect in terms of the average of peak moments and the average exceeding proportional limit moments. For the conservative design of a naval ship under UNDEX, it is recommended to use incompressible fluid. In the viewpoint of cost-effective naval ship design, the inelastic effects should be taken into account.

Estimation of the Terminal Velocity of the Worst-Case Fragment in an Underwater Torpedo Explosion Using an MM-ALE Finite Element Simulation (MM-ALE 유한요소 시뮬레이션을 이용한 수중 어뢰폭발에서의 최악파편의 종단속도 추정)

  • Choi, Byung-Hee;Ryu, Chang-Ha
    • Explosives and Blasting
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    • v.37 no.3
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    • pp.13-24
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    • 2019
  • This paper was prepared to investigate the behavior of fragments in underwater torpedo explosion beneath a frigate or surface ship by using an explicit finite element analysis. In this study, a fluid-structure interaction (FSI) methodology, called the multi-material arbitrary Lagrangian-Eulerian (MM-ALE) approach in LS-DYNA, was employed to obtain the responses of the torpedo fragments and frigate hull to the explosion. The Euler models for the analysis were comprised of air, water, and explosive, while the Lagrange models consisted of the fragment and the hull. The focus of this modeling was to examine whether a worst-case fragment could penetrate the frigate hull located close (4.5 m) to the exploding torpedo. The simulation was performed in two separate steps. At first, with the assumption that the expanding skin of the torpedo had been torn apart by consuming 30% of the explosive energy, the initial velocity of the worst-case fragment was sought based on a well-known experimental result concerning the fragment velocity in underwater bomb explosion. Then, the terminal velocity of the worst-case fragment that is expected to occur before the fragment hit the frigate hull was sought in the second step. Under the given conditions, the possible initial velocities of the worst-case fragment were found to be very fast (400 and 1000 m/s). But, the velocity difference between the fragment and the hull was merely 4 m/s at the instant of collision. This result was likely to be due to both the tremendous drag force exerted by the water and the non-failure condition given to the frigate hull. Anyway, at least under the given conditions, it is thought that the worst-case fragment seldom penetrate the frigate hull because there is no significant velocity difference between them.

읽을거리 - 항공기 실전원리(12) - 바다 속 기뢰를 찾아라, 소해헬기(AMCM)

  • 한국항공우주산업진흥협회
    • Aerospace Industry
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    • s.107
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    • pp.68-69
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    • 2010
  • 기뢰(機雷, naval mine) 또는 수뢰((水雷)는 수중에 설치되어 함선이 접근 또는 접촉했을 때, 자동 또는 원격 조작에 의해 폭발하는 수중 병기다. 저렴하고 단순하지만 가장 현대적이고 강력한 해군조차도 겁내하는 해중무기다. 적상선 및 잠수함 공격에 효과적인 무기로 미국 남북전쟁을 기점으로 대량 사용되었다. 기뢰의 다양화, 지능화에 따라 적의 기뢰를 찾아 파괴하는 소해임무도 함께 강조되고 있다. 함정의 안전한 해상작전을 위해서는 반드시 따라야 하는 대기뢰전, 특히 헬기를 이용한 '공중 대기뢰전(Airborne Mine countermeasures)'은 현대 해군의 필수다. 세계 주요 소해헬기와 관련 기술에 대해 소개한다.

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Performance Evaluation of Shock, Vibration and Structure-borne Noise for Double-resilient Mounting Engine Module (이중탄성지지 함정용주기관의 충격, 진동 및 고체음 성능평가)

  • 유광택;박정근;정정훈;김병현
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.1048-1052
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    • 1996
  • 함정용 주기관은 내충격 및 고체음 저감을 위하여 이중탄성지지시스템으로 설치되고 있다. 이중탄성지 지에 의한 방법은 기뢰(mines)의 비접촉 수중폭발 공격으로부터 충격손상을 방지하며, 또한 수중으로 고체음이 전파되어 피탐되는 가능성을 저감하는데 그 목적이 있다.(중략)

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