• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.911-915
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• 2014

Pyrotechnic devices are widely used for space appendages. However, a cube satellite requirements do not permit the use of explosive pyrotechnic device. A nichrome burn wire release has typically been used for holding and release of deployable appendages of the cube satellite due to its simplicity and low cost. However, relatively low mechanical constraint force and system complexity for application of multi-deployable systems are disadvantages of the conventional mechanism. To overcome these drawbacks, we have developed a segmented nut type holding and release mechanism based on the nichrome burn wire release. The great advantages of the mechanism are much lower shock level and larger constraint force than the conventional mechanism using pyro. Flight model for on-orbit verification was developed and verified through release function test, vibration test and thermal vacuum test.

• Journal of the Korean Chemical Society
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• v.48 no.1
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• pp.12-16
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• 2004

The ignition of ethanol-oxygen-argon mixture was studied in reflected shock waves over the temperature range of 1281-1625 K and the pressure range of 0.69-1.06 bar. The ignition delay time was measured by the sudden increase of pressure profile and the radiation emitted by OH radicals. The relationship between the ignition delay time and the concentrations of ethanol and oxygen was determined in the form of mass-action expressions with an Arrhenius temperature dependence. In contrast to the behavior observed in methanol, ethanol acts to inhibit rather than accelerate its own ignition. Several kinetic mechanisms proposed for ethanol oxidation at high temperatures have been tested by the computer simulation.

• Journal of Periodontal and Implant Science
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• v.41 no.2
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• pp.54-59
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• 2011

Purpose: The aim of this study was to define the immunoreactive specificity of Porphyromonas gingivalis (P. gingivalis) heat shock protein (HSP) 60 in periodontitis and atherosclerosis. Methods: In an attempt to define the cross-reactive bacterial heat-shock protein with human self-antigen at molecular level, we have introduced a novel strategy for cloning hybridoma producing anti-P. gingivalis HSP 60 which is polyreactive to bacterial HSPs or to the human homolog. Results: Five cross-reactive clones were obtained which recognized the #19 peptide (TLVVNRLRGSLKICAVKAPG) among 37 synthetic peptides (20-mer, 5 amino acids overlapping) spanning the whole molecule of P. gingivalis HSP 60. We have also established three anti-P. gingivalis HSP 60 monoclonal antibodies demonstrating mono-specificity. These clones recognized the #29 peptide (TVPGGGTTYIRAIAALEGLK). Conclusions: Peptide #19 and #29 of P. gingivalis HSP 60 might be important immunoreactive epitopes in the immuno-pathogenic mechanism of bacterial antigen-triggered autoimmune diseases.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.10
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• pp.1166-1173
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• 2011

There have been many researches about SUGV (Small Unmanned Ground Vehicle) mechanism regarding off-road mobility and obstacle negotiation. This paper introduces an analysis of geometry parameters to enhance the vertical obstacle negotiation ability for the SUGV. Moreover, this paper proposes an anti-shock structure analysis of wheels to protect the main body of the SUGV when it falls off a vertical obstacle. Major system geometry parameters will be determined under certain constraints. The constraints and optimization problem for maximizing the ability of vertical obstacle negotiation will be presented and discussed. Dynamic simulation results and experiments with manufactured platform will also be presented to validate the analysis. Several types of wheel materials and structures will be compared to determine the best anti-shock wheel design through FEM (Finite Element Method) simulations.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.47-52
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• 2005

A lot of information storage devices have been introduced and developed for recently years. The trends of those devices are high capacity, compact size, low power consumption, reliability, and removability for data interchange with other device. As a satisfaction of these trends, near-field technique is in the spotlight as the next generation device. In order for a near-field recording to be successfully implemented in the storage device, a slider and suspension is introduced as actuating mechanism. The optical slider is designed considering near-filed optics. Suspension is not only supports slider performance, and tracking servo capacity but also meets the optical characteristics such as tilt aberration, and guarantee to satisfy shock performances for the mobility fir the actuator. In this study, the optical slider and the suspension for near-field probe array are designed and analyzed considering dynamic performance of head-gimbal assembly and shock simulation..

• Journal of The Korean Astronomical Society
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• v.34 no.4
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• pp.281-283
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• 2001

As a companion to an adiabatic version developed by Ryu and his coworkers, we have built an isothermal magnetohydrodynamic code for astrophysical flows. It is suited for the dynamical simulations of flows where cooling timescale is much shorter than dynamical timescale, as well as for turbulence and dynamo simulations in which detailed energetics are unimportant. Since a simple isothermal equation of state substitutes the energy conservation equation, the numerical schemes for isothermal flows are simpler (no contact discontinuity) than those for adiabatic flows and the resulting code is faster. Tests for shock tubes and Alfven wave decay have shown that our isothermal code has not only a good shock capturing ability, but also numerical dissipation smaller than its adiabatic analogue. As a real astrophysical application of the code, we have simulated the nonlinear three-dimensional evolution of the Parker instability. A factor of two enhancement in vertical column density has been achieved at most, and the main structures formed are sheet-like and aligned with the mean field direction. We conclude that the Parker instability alone is not a viable formation mechanism of the giant molecular clouds.

• Journal of The Korean Dental Society of Anesthesiology
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• v.6 no.2 s.11
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• pp.121-126
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• 2006

Generalized anaphylaxis is a most dramatic and acutely life-threatening allergic reaction. Most fatalities from anaphylaxis occur within the first 30 minutes postantigenic exposure. The mechanism of generalized anaphylaxis is the reaction of IgE antibodies to an allergen that causes the release of histamine, bradykinin, and others. These chemical mediators cause the contraction of smooth muscles of the respiratory and intestinal tracts, as well as increased vascular permeability. Four major clinical symptoms are recognized: skin reactions, smooth muscle spasm (gastrointestinal and genitourinary tracts and respiratory smooth muscle), respiratory distress, and cardiovascular collapse. Epinephrine is the drug of choice for the management. Its syrnpathomimetic effects directly counteract most aspects of the attack. Respiration must be immediately supported by the establishment of a patent airway along with artificial ventilation. The circulation should be supported and the existing hypotension overcome by placing the victim in a position to allow gravity to aid venous return and by administering intravenous fluids, vasopressors, and corticosteroids. When an imperceptible pulse is evident, external cardiac compression must also be instituted. This is a case report of anaphylactic shock care during general anesthesia, possibly due to penicillin, pancuronium and others.

• Animal cells and systems
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• v.14 no.4
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• pp.267-274
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• 2010

The decrease in sperm quality under heat stress causes a great loss in animal husbandry production. In order to reveal the mechanism underlying the sperm quality decrease caused by heat stress, we first established a mild heat-treated mouse model. Then, the sperm quality was identified. Further, the testicular proteome profile was mapped and compared with the control using 2D electrophoresis and mass spectrometry. Finally, the differential expressed proteins involved in the heat stress response were identified by real-time PCR and Western blotting. The results showed that heat stress caused a significant reduction in mouse sperm quality (P<0.05). Further, 52 protein spots on the 2D gel were found to differ between the heat-shocked tissues and the control. Of these spots, some repair proteins which might provide some explanation for the influence on sperm quality were found. We then focused on Bag-1, Hsp40, Hsp60 and Hsp70, which were found to be differently expressed after heat shock (P<0.05). Further analysis in this heat-shocked model suggests numerous potential mechanisms for heat shock-induced spermatogenic disorders.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.433-436
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• 2004

In this paper, we studied on the electrical safety evaluations of transformer insulation cover. In order to take preventive measures against an electric shock disaster in 22.9kV transformer installation, we put the insulation cover on a transformer charging parts. It needs to be designed so that the insulation covers have superior properties such as, arc-resistance, weather-resistance and heat-resistance, because they are used until the damage and destruction occur. To establish the protection cover to reduce the electrical shock, we analyzed damage mechanism and risk factors which happened by structural fault of an insulation cover in this paper. Also, based on the experimental results, we are planing to suggest new improved insulation cover models.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.51.1-51.1
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• 2021

Merger shocks with M_s < ~ 3 - 4 have been detected in galaxy clusters through radio observations of synchrotron radiations emitted from cosmic-ray (CR) electrons. The CR electrons are believed to be produced by the so-called diffusive shock acceleration (DSA) at the merger shocks. To describe the acceleration of electrons, the injection into DSA has to be understood. Recent studies have showed that electrons could be energized through stochastic shock drift acceleration (SSDA), a mechanism mediated by multi-scale plasma waves at shock transition zone. However, such preacceleration process seems to be effective only at the supercritical shocks with M_s > ~ 2.3, implying that further studies should be done to explain radio relics with weaker shocks. In this talk, we present the results obtained by fully kinetic 2D particle-in-cell (PIC) simulations, which include pre-existing suprathermal electrons possibly ejected from active galactic nuclei (AGNs) or produced by previous episodes of turbulence/shocks. The simulations indicate that the pre-existing electrons enhance the upstream plasma waves in shocks with M_s < ~ 2.3. However, the wavelength of such waves is not long enough to scatter off suprathermal electrons and energize them to the injection momentum for DSA. Hence, we conclude that preexciting suprathermal electrons alone would not solve the problem of electron acceleration at radio relic shocks.