• 제목/요약/키워드: Shock pulse

검색결과 107건 처리시간 0.046초

레이저 광원 형상이 레이저 충격 피닝 잔류응력에 미치는 영향 (Effects of Laser Source Geometry on Laser Shock Peening Residual Stress)

  • 김주희;김윤재;김정수
    • 대한기계학회논문집A
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    • 제36권6호
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    • pp.609-615
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    • 2012
  • 레이저 충격 피닝 처리 시 레이저 광원으로부터 금속표면에 조사되는 레이저 빔 형상은 다양하다. 레이저 형상은 표면에서 발생하는 압력파의 특성을 결정하기 때문에 금속 표면과 깊이 방향에 대한 잔류응력 분포에 영향을 미칠 수 있다. 본 논문에서는 레이저 충격 피닝 처리시 레이저 광원 형상이 인코넬 alloy 600 합금의 잔류응력에 미치는 영향을 분석하였다. 레이저 광원 형상은 원형, 사각형, 타원형 형상이 고려되었으며, 표면과 깊이 방향에 대한 압축잔류응력 특성을 비교하였다. 표면에서 생성되는 압축잔류응력은 원형 레이저 형상이 최대이지만 중심부에서 인장응력이 발생하고, 깊이 방향에서는 타원형 레이저 형상이 최대 압축잔류응력을 생성한다. 소성변형 발생 깊이는 사각형에 비해 원형과 타원형이 양호하다.

정혈(井穴) 자락요법(刺絡療法)에 관(關)한 문헌고찰(文獻考察) (The Literature Study on Jung point venesection therapy)

  • 김윤희;이현;이병렬
    • 혜화의학회지
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    • 제10권1호
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    • pp.237-245
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    • 2001
  • I have come to next conclusions in consequnce of documentary study about medical books of many generations regarding Jung point venesection therapy. 1. Jung point is significant as the beginning of pulse energy flow on meridian, the origin of all meridional pulse energy being located at extrimity terminal, confluence of three yin and three yang, and emergent treatment point. 2. Jung point venesection therapy was much used for the first-aid treatment for acute and thermic disease, and that is the combination of the meaning as of restoration from death and emergent treatment of Jung point and function of openning of orifice, leakage of fever, circulation of blood, remove of edema of venesection therapy. 3. It is very much used for emergency case, five sensory organ disease and CVA, heating shock and so on. Besides that digestive disease, cough, fever with cold, childhood disease, cardiac ache, thoracic disease, numbness of digitus terminal, mental disorder follow that in order. 4. Sosang, Jung point of Arm Greater Yin Lung meridian, is very much used for five sensory organ disease. Sosang is for orbital disease, sangyang for auditory disease, sosang for nasal disease, and sosnag for introitus-throat disease. 5. Ten Jung point is most used for first-aid diseases of CVA, heating shock. 6. Ten Jung point is most used for digestive disease of stomach ache, vomiting, diarrhea, intestinal convulsion. 7. Ten Jung point is most used for cold disease of cough, fever, malaria. 8. Ten Jung point, sosang, kwanchung are much used for childhood disease of acute convulsion and fever. 9. Among Jung point, sosang is most used, 34 times. Next there are Ten Jung point, kwanchung, sangyang, sotaek, jungchung, unbaek, taedon in order. In the order of frequency in use, arm channel is more used than leg channel.

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Miniature Schnauzer에서 발생한 장간막 염전 1증례 (Mesenteric torsion in a Miniature Schnauzer)

  • 최지혜;김현욱;김진경;장재영;김준영;윤정희
    • 대한수의학회지
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    • 제48권1호
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    • pp.125-130
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    • 2008
  • Mesenteric torsion was diagnosed in a 2-year-old, spayed female Miniature Schnauzer. The patient was presented with acute depression, vomiting, lethargy and hematochezia. On physical examination, severe dehydration, tachycardia, tachypnea, weak femoral pulse, delayed capillary refill time and pale mucous membrane were found and the dog was in shock. Radiography and ultrasonography revealed intestines distended with gas, ascites and the "C" shaped distended intestine. Medical treatments including fluid therapy, analgesics, antibiotics and lidocaine for reducing reperfusion injury were applied. And then, the mesenteric torsion was definitively diagnosed through exploratory laparotomy and intestinal resection and anastomosis were performed. The dog made an uneventful recovery and was free of clinical sign one week after surgery. Mesenteric torsion is an unusual and life-threatening disease in dogs. It has usually been described in the middle and large breed dogs, especially German Shepherds. However, the mesenteric torsion should be included in the differential diagnostic lists for acute abdomen even in small breed dog. The mortality rate of mesenteric torsion can be reduced through prompt diagnosis, proper preventive therapy for shock and reperfusion injury and emergency surgery.

무차원 변수 해석을 이용한 LSP 공정변수 영향 분석 (Study on Effect of LSP Process Parameters Using Dimensionless Analysis)

  • 김주희;김태양;김윤재
    • 대한기계학회논문집A
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    • 제37권9호
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    • pp.1141-1149
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    • 2013
  • 복잡한 물리적 현상에 대한 수학적 모델을 만들기 위해 적용되는 차원해석은 LSP 공정변수의 영향을 이해하는데 중요한 도구가 된다. 본 연구에서는 버킹검(Buckingham) ${\prod}$이론을 이용한 차원해석을 통해 레이저 충격 피닝의 잔류응력 결과에 영향을 미치는 변수를 확인하고, 유한요소법을 이용하여 LSP 공정변수인 최대압력파, 압력파 지속시간, 레이저 샷 크기 및 다중 LSP 에 대한 잔류응력 결과를 확인하였다.

레이저와 질소가스 상호충돌로부터 발생되는 플라스마 가시화 (Visualization of Plasma Produced in a Laser Beam and Gas Jet Interaction)

  • 김종욱;김창범;김광훈;이해준;석희용
    • 한국가시화정보학회:학술대회논문집
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    • 한국가시화정보학회 2002년도 추계학술대회 논문집
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    • pp.39-42
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    • 2002
  • In the current study, characteristics of the laser-induced plasma were investigated in a gas filled chamber or in a gas jet by using a relatively low intensity laser $(I\;\leq\;5\;\times\;10^{12}\;W/cm^2)$. Temporal evolutions of the produced plasma were measured using the shadow visualization and the shock wave propagation as well as the electron density profiles in the plasma channel was measured using the Mach-Zehnder interferometry. Experimental results such as the structure of the produced plasma, shock propagation speed $(V_s)$, electron density profiles $(n_e)$, and the electron temperature $(T_e)$ are discussed in this study. Since the diagnostic laser pulse occurs over short time intervals compared to the hydrodynamic time scales of expanding plasma or a gas jet, all the transient motion occurring during the measurement is assumed to be essentially frozen. Therefore, temporally well-resolved quantitative measurements were possible in this study.

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축소관과 확대관 출구로부터 방출되는 펄스파에 관한 연구 (A Study on the Impulse Waves Discharged from the Exit of the Convergent and Divergent Pipes)

  • 이동훈;이명호;권용훈;김희동;박종호
    • 한국소음진동공학회논문집
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    • 제12권5호
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    • pp.346-354
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    • 2002
  • The present study is to investigate the propagation characteristics of the impulse waves discharged from the exit of the convergent and divergent pipes. An experiment is carried out using a shock tube with an open end and is compared to the computation of the axisymmetric, compressible, unsteady Euler equations, which are solved by the second-order total variation diminishing (TVD) scheme. For the computational work, several initial compression waves are assumed inside the pipe so that those are the same to the experimental ones of the shock tube. The results show that the peak pressures of the impulse waves discharged from the exit of convergent and divergent pipes decrease with an increase in the wavelength of the initial compression wave. All of the impulse waves have a strong directivity toward the pipe axis, regardless of the exit type of the pipe employed. The impulse waves discharged from the divergent pipe are stronger than those from the straight pipe, while the impulse waves of the convergent pipe are weaker than those from the straight pipe. It is found that the convergent pipe can play a role of a passive control to reduce the peak pressure of the impulse wave. The present computations represent the experimented impulse waves with a good accuracy.

레이저 펄스 에너지를 이용한 무통증 마이크로젯 약물전달시스템 (Painless Microjet Injector Using Laser Pulse Energy)

  • 여재익;한태희;하정무
    • 대한기계학회논문집B
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    • 제35권5호
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    • pp.547-550
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    • 2011
  • 레이저 기반의 무바늘 액체 약물전달장치는 계속해서 개발되어왔다. 레이저 빔이 고무 챔버 내부의 액체에 모이게 된다. 초점이 맞춰진 레이저 빔은 공기방울을 생성시키고 급격히 팽창하게 된다. 밀봉된 챔버 안쪽에서의 급격한 부피변화는 액체약물을 마이크로 노즐을 통해 빠르게 밀어내어 마이크로 약물젯을 생성한다. 노즐의 출구지름은 100 ${\mu}m$ 이하이며 본 연구팀은 생성된 마이크로 약물젯의 속도가 인체의 연조직으로 침투시키기에 충분함을 확인하였다. 이 실험에서는 사람의 혈전을 모사한 무게 비 5%의 젤라틴 수용액을 냉각시킨 샘플과 돼지 지방층을 사용하여 침투실험을 수행하였다.

전차대대 주요체계의 EMP 방호능력 발전방안에 관한 연구 (The Development of Electromagnetic pulse Protection Capability in the Main System of a Tank Battalion)

  • 최호갑;한재덕;손상우;김성곤
    • 대한토목학회논문집
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    • 제40권6호
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    • pp.623-631
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    • 2020
  • 핵무기 공격 시나 전자폭탄의 공겨 시 발생하는 전자기펄스(EMP: electromagnetic pulse)는 무기체계, 정보기기, 유·무선 통신장비, 전력공급 장비 등에 영향을 주어 전장에서 혼란을 초래하게 한다. 지금까지의 군에 적용 중인 EMP 방호에 대한 기준은 고정 및 이동시설과 장비를 중심으로 되어 있어 무기체계 중심의 단일 전술제대에 대한 EMP 방호 소요에 대한 연구가 필요한 실정이다. 본 연구에서는 전술제대 중 기동력과 화력, 충격력을 지닌 전차대대의 전차와 지휘용장갑차를 중심으로 EMP에 취약한 지휘통제, 기동, 화력체계에 대하여 EMP 방호기준을 설정하고, EMP 차폐 및 차단 등 EMP 방호능력 발전방안을 구체적으로 제시하였다. 이를 통해 EMP 상황하 부대 지휘통제와 부대원의 생존성을 보장하고 임무수행 여건을 보장하고자 한다.

글라스 세라믹 구형 돔의 충격파괴 모델링 기법 연구 (A Study on the Impact Fracture Modeling Techniques of Glass-Ceramic Spherical Dome)

  • 이정희;이영신;김재훈;공정표;구송회;문순일
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2007년도 춘계학술대회A
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    • pp.226-231
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    • 2007
  • This paper studied on the impact fracture modeling techniques of spherical dome with MACOR glass-ceramic. The glass ceramic material has bigger compressive strength than the tensile strength and endure well at high temperature. The fracture simulation under shock perssure was performed by the finite element method with nonlinear code LS-Dyna. The simulation was carried out by 3 type dome models under step impact pulse shape. 4-node shell element and 8-node solid element were used for analysis.

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Analysis and Design of a New Topology of Soft-Switching Inverters

  • Chen, Rong;Zhang, Jia-Sheng
    • Journal of Power Electronics
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    • 제13권1호
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    • pp.51-58
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    • 2013
  • This paper proposes the power conversion mechanism of a bailer-charge-transfer zero-current-switching (CT-ZCS) circuit. The operation modes are analyzed and researched using state trajectory equations. The topology of CT-ZCS based on soft-switching inverters offers some merits such as: tracking the input reference signal dynamically, bearing load shock and short circuit, multiplying inverter N+1 redundancy parallel, coordinating power balance for easy control, and soft-switching commutation for high efficiency and large capacity. These advantages are distinctive from conventional inverter topologies and are especially demanded in AC drives: new energy generation and grid, distributed generation systems, switching power amplifier, active power filter, and reactive power compensation and so on. Prototype is manufactured and experiment results show the feasibility and dynamic voltage-tracking characteristics of the topology.