• Title/Summary/Keyword: Laser-induced Shock

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Visualization of Interacting Parallel Supersonic Free Jets using NO-LIF

  • Niimi Tomohide;Ishida Toshihiko
    • 한국가시화정보학회:학술대회논문집
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    • 2001.12a
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    • pp.36-43
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    • 2001
  • The flow field structures of two interacting parallel supersonic free jets are studied by flow visualization using planar laser-induced fluorescence of NO seeded in nitrogen gas. The experiments are carried out for several distances between two orifice centers and for various ratios of the pressure in the reservoir to that in the expansion chamber. The flow fields are visualized mainly on the plane including two jet centerlines and its characteristic shock system, especially a cell structure formed secondly by interaction of two jets, are analyzed. The positions of the normal shock depending on the pressure ratios are also compared.

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An Experimental Study on the Effect of Low Level Laser and Some Cytokines on Gene Expression of Human Gingival Fibroblasts (저출력레이저조사와 염증성 자극물질이 치은섬유아세포의 유전자 발현에 미치는 영향에 관한 실험적 연구)

  • Jung-Min Kim;Keum-Back Shin
    • Journal of Oral Medicine and Pain
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    • v.19 no.2
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    • pp.57-71
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    • 1994
  • Gingival fibroblasts were cultured and subjected to the test of Northern blot analysis for the demonstration of various mRNA expression in response to the low level laser treatment. For duplication of in vivo. Wound healing process, fibroblasts were pretreated with proinflammatory cytokine interleukin-1$\beta$(IL-1$\beta$) or mitogenic substance phorbol 12-myristate 13-acetate(PMA) prior to laser irradiation. The results were as follows : 1. By the laser irradiation, the gene expression of collagen type I was markedly increased I n gingival fibroblasts, especially in the case of PMA pretreatment. The gene expression of collagen type IV, however, was not only affected by laser irradiation but also by chemical cell stimulation. 2. Oncogene v-myc expression was affected by both laser irradiation and IL-1$\beta$ or PMA stimulation, But v-fos gene expression was not detected in any case of this experimental system. 3. Heat shock gene(Hsp 70)was expressed constiutively, but slightly increased by laser irradiation. 4. mRNA of fibroblast growth factor(FGF) was induced by both laser irradiation and IL-1$\beta$ or PMA treatment.

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Expression of Heat Shock Protein Protein 70 in Umbilical Vein Endothelial Cells Infected by Staphylococcus aureus

  • Chang, Hyun-Ah;Chang, Jun-Keun;Kim, Jong-Won;Kim, Mal-Nam
    • Journal of Microbiology and Biotechnology
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    • v.10 no.2
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    • pp.137-142
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    • 2000
  • Environmental stres is known to induce heat shock proteins (HSPs) in eukaryotic cells. However, the induction of HSPs in host cells by microbial infection has not yet been well explained. Staphylococcus aureus (S. aureus) is one of the major pathogens in the pathogenesis of endovascular diseases such as infective endocarditis. In this study, the synthesis of stress-inducible 70 kDa HSP was investigated in the endothelial cells (ECs) after 3 h to 20 h of incubation with S. aureus. The dffect of S. aureus infection on the expression of HSP70 in cultured ECs was analyzed using laser scanning confocal microscopy (LSCM). The increase of HSP70 expression in ECs infected by S. aureus ($10^4{\;}cfu/ml$) for 20 h was 1.1-fold higher than that in heat shock treated ECs and 2.2-fold higher than that in untreated cells. Heat shock is known to induce intranucleus HSP70 expression in mammalian cells, whereas the S. aureus infection induced perinuclear expression in ECs as observed by LSCM. Consequently, the expression of HSP70 in ECs plays an important role in the pathogenesis of endovascular infection.

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Thermal shock characteristics of FGM for gas turbine blade (가스터빈 날개용 경사기능재료의 열충격 특성)

  • Lim, Jae-Kyoo;Song, Jun-Hee;Kim, You-Jig
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.1
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    • pp.73-79
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    • 1998
  • The development of a new material which should be continuously usable under severe environment of very high temperature has been urgently requested. The conventional thermal barrier coating(TBC) is a two layer coating, but a composition and a microstructure of functionally graded material(FGM) are varied continuously from place to place in ways designed to provide it with the maximum function of mitigating the induced thermal stress. The purpose of this study is to evaluate the heat-resistant characteristics by thermal shock of laser and furnace heating. The fracture behaviors of non-FGM(NFGM) and FGM were investigated based on acoustic emission(AE) technique during thermal shock test. Therefore, it can be concluded that FGM gives higher thermal resistance compared to NFGM by AE signal and fracture surface analysis.

Design of Polymer Composites for Effective Shockwave Attenuation (충격파 완화 복합재의 설계)

  • Gyeongmin Park;Seungrae Cho;Hyejin Kim;Jaejun Lee
    • Composites Research
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    • v.37 no.1
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    • pp.21-31
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    • 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.

The Activation of Stress-induced Heat Shock Protein 27 and the Relationship of Physical Therapy (스트레스-유도 열충격단백질 27(Heat Shock Protein 27)의 활성과 물리치료의 상관성)

  • Kim, Mi-Sun;Lee, Sung-Ho;Kim, Il-Hyun;Hwang, Byong-Yong;Kim, Jung-Hwan
    • The Journal of Korean Physical Therapy
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    • v.20 no.1
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    • pp.57-65
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    • 2008
  • Purpose: Heat shock proteins (HSPs) are a group of proteins that are activated when cells are exposed to a variety of environmental stresses, such as infection, inflammation, exposure to toxins, starvation, hypoxia, brain injury, or water deprivation. The activation of HSPs by environmental stress plays a key role in signal transduction, including cytoprotection, molecular chaperone, anti-apoptotic effect, and anti-aging effects. However, the precise mechanism for the action of small HSPs, such as HSP27 and mitogen-activated protein kinases (MAPKs: extracellular-regulated protein kinase 1/2 (ERK1/2), p38MAPK, stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), is not completely understood, particularly in application of cell stimulators including platelet-derived growth factor (PDGF), angiotensin II (AngII), tumor necrosis factor $\alpha$ (TNF$\alpha$), and $H_2O_2$. This study examined the relationship between stimulators-induced enzymatic activity of HSP27 and MAPKs from rat smooth and skeletal muscles. Methods: 2-dimensional electrophoresis (2DE) and matrix assisted laser desorption ionizationtime-of-flight/time-of-flight (MALDI-TOF/TOF) analysis were used to identify HSP27 from the intact vascular smooth and skeletal muscles. Three isoforms of HSP27 were detected on silver-stained gels of the whole protein extracts from the rat aortic smooth and skeletal muscle strips. Results: The expression of PDGF, AngII, TNF$\alpha$, and $H_2O_2$-induced activation of HSP27, p38MAPK, ERK1/2, and SAPK/JNK was higher in the smooth muscle cells than the control. SB203580 (30${\mu}$M), a p38MAPK inhibitor, increased the level of HSP27 phosphorylation induced by stimulators in smooth muscle cells. Furthermore, the age-related and starvation-induced activation of HSP27 was higher in skeletal muscle cells (L6 myoblast cell lines) and muscle strips than the control. Conclusion: These results suggest, in part, that the activity of HSP27 and MAPKs affect stressors, such as PDGF, AngII, TNF$\alpha$, $H_2O_2$, and starvation in rat smooth and skeletal muscles. However, more systemic research will be needed into physical therapy, including thermotherapy, electrotherapy, radiotherapy and others.

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Development of shock wave induced microparticle acceleration system based on laser ablation and its application on drug delivery (충격파를 이용한 레이저 어블레이션 기반의 마이크로 입자 가속 시스템 개발 및 약물전달 응용)

  • Choi, Ji-Hee;Gojani, Ardian B.;Lee, Hyun-Hee;Yoh, Jai-Ick
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.6
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    • pp.587-593
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    • 2008
  • Transdermal and topical drug delivery with minimal tissue damage has been an area of vigorous research for years. Our research team has initiated the development of an effective method for delivering drug particles across the skin (transdermal) for systemic circulation, and to localized (topical) areas. The device consists of a laser ablation based micro-particle acceleration system that can be integrated with endoscopic surgical techniques. We have successfully delivered 3μm size cobalt particles into gelatin models that represent soft tissue with remarkable penetration depth.

Wave Drag Reduction due to Repetitive Laser Pulses (반복 레이저 펄스를 이용한 초음속 비행체의 항력저감)

  • Kim, Jae-Hyung;Sasoh, Akihiro;Kim, Heuy-Dong
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.04a
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    • pp.381-384
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    • 2011
  • Wave drag reduction due to the repetitive laser induced energy deposition over a flat-nosed cylinder is experimentally conducted in this study. Irradiated laser pulses are focused by a convex lens installed in side of the in-draft wind tunnel of Mach 1.94. The maximum frequency of the energy deposition is limited up to 80. Time-averaged drag force is measured using a low friction piston which was backed by a load cell in a cavity as a controlled pressure. Stagnation pressure history, which is measured at the nose of the model, is synchronized with corresponding sequential schlieren images. With cylinder model, amount of drag reduction is linearly increased with input laser power. The power gain only depends upon the pulse energy. A drag reduction about 21% which corresponds to power gain of energy deposition of approximately 10 was obtained.

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Experimental Study on Upstream Fueled Cavity Flame-Holder Scramjet Engine (상류 분사 공동 화염 지지부를 가지는 스크램제트 엔진에 관한 실험적 연구)

  • Jeong, Eun-Ju;Jeung, In-Seuck;O'Byrne, Sean;Houwing, A.F.P.
    • Journal of the Korean Society of Combustion
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    • v.11 no.4
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    • pp.1-8
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    • 2006
  • The model cavity scramjet engine experiments are carried out using T3 free-piston shock tunnel. Upstream hydrogen fuel is injected before the cavity with different injection pressure. OH planar laser-induced fluorescence is used to investigate the combustion zone and piezoelectric pressure transducers are used to define the pressure rise due to the combustion. Main combustion region is a mixing layer which is between air and fuel. Also high OH fluorescence signal is appeared in the shear layer above the cavity in high equivalence ratio. From the OH signal in the cavity, this fuel injection system can be a role as a flame-holder.

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Experimental Study on Upstream Fueled Cavity Flame-Holder Scramjet Engine (상류 분사 공동 화염 지지부를 가지는 스크램제트 엔진에 관한 실험적 연구)

  • Jeung, In-Seuck;O'Byrne, Sean;Houwing, A.F.P.;Jeong, Eun-Ju
    • 한국연소학회:학술대회논문집
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    • 2006.04a
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    • pp.197-204
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    • 2006
  • The model cavity scramjet engine experiments are carried out using T3 free-piston shock tunnel. Upstream hydrogen fuel is injected before the cavity with different injection pressure. OH planar laser-induced fluorescence is used to investigate the combustion zone and piezoelectric pressure transducers are used to define the pressure rise due to the combustion. Main combustion region is a mixing layer which is between air and fuel. Also high OH fluorescence signal is appeared in the shear layer above the cavity in high equivalence ratio. From the OH signal in the cavity, this fuel injection system can be a role as a flame- holder.

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