• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.117-120
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• 2002

An experimental research has been carried out for flow control of the shock wave/turbulent boundary-layer interaction utilizing aeroelastic mesoflaps. Various shapes and thicknesses of the mesoflap are tested to achieve different deflections of the flap, and ail the results are compared to the solid-wall reference case without flow-control mechanism. Quantitative variation of skin friction has been measured downstream of the interactions using the laser interferometer skin friction meter, and qualitative skin friction distribution has been obtained by observing the interference fringe pattern on the oil-film surface. A strong spanwise variation in the fringe patterns with a narrow region of separation near the centerline is noticed to form behind the shock structure, which phenomenon is presumed partially related to three-dimensional flow structures associated with both the sidewalls and the bottom test surface. The effect of the shape of the cavity is also observed and it is noticed that the shape of the cavity is not negligible.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1730-1735
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• 2003

The plume-induced shock wave is a complex phenomenon, consisting of plume-induced boundary layer separation, separated shear layer, multiple shock waves, and their interactions. The knowledge base of plume interference effect on powered missiles and flight vehicles is not yet adequate to get an overall insight of the flow physics. Computational studies are performed to better understand the flow physics of the plume-induced shock and separation particularly at high plume to exit pressure ratio. Test model configurations are a simplified missile model and two rounded and porous afterbodies to simulate moderately and highly underexpanded exhaust plumes at the transonic/supersonic speeds. The result shows that the rounded afterbody and porous wall attached at the missile base can alleviate the plume-induced shock wave phenomenon, and improve the control of the missile body.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.621-626
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• 2000

Reduction in pressure transients may be important in the hydraulic system and necessary to avoid failure and to improve the efficiency of operation. This study addresses the design and use of an orifice to provide the desired control of the hydraulic actuator system. The experimental apparatus is a model of an automobile shift system. Control is accomplished by installing four different diameter ratio of orifices at appropriate locations in the system. Experimental results show that the orifice can be used to obtain the control of shock and the control level depends on the orifice size, orifice type, operating conditions.

• 한국전산유체공학회:학술대회논문집
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• 2001.05a
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• pp.99-104
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• 2001

This paper deals with the development of shock stable scheme that is free from shock instability. Roe's FDS is known to preserve good accuracy but to suffer from shock instability, i.e. the carbuncle phenomenon. As the first step toward the shock stable scheme, Roe's FDS is compared with HLLE scheme to identify the source of shock instability. Then control function f is introduced into the pressure term in Roe's FDS to cure shock instability. Various numerical tests concerned with shock instability are performed to demonstrate the shock stability of the proposed scheme.

• The Korean Journal of Physiology
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• v.2 no.1
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• pp.47-52
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• 1968

Twenty white rabbits anesthetized with nembutal (30 mg/kg) were employed in this experiment. Five of them served as controls; the remaining rabbits as experimental group were subjected to irreversible hemorrhagic shock. Shock was induced by bleeding the animals until mean blood pressure decreased to a level of 50-40 mmHg. This level of pressure was maintained for 3-4 hours, after which the drawn blood was reinfused. The reinfusion of blood caused the elevation of arterial pressure almost the control level for some minutes, after which a gradual and progressive decline of blood pressure became evident. This decline was thought to be the result from irreversible hemorrhagic shock. When mean blood pressure declined to less than 50 mmHg, chest was opened and samples of arterial blood and left ventricular muscle were taken. Left ventricular muscle and blood plasma were analyzed for potassium, sodium, chloride and water content. Blood glucose concentration was determined by Somogyi-Nelson's method. Extracellular and intracellular myocardial water and electrolyte content were calculated on the basis that electrolytes are distributed between plasma water and interstitial water according to Gibbs-Donnan equilibrium. In this calculation extracellular water was substituted for Na space. The findings obtained were as follows: 1. The concentration of blood glucose was 87mg% in the controls and it rose to 222 mg% in shock (P<0.01). 2. Plasma potassium elevated significantly from 3.3 mEq/l in controls to 8.0 mEq/l in shock (P<0.01), while small decreases in sodium (151-146 mEq/l) and chloride (102-96 mEq/l) were observed (P<0.3, P<0.1), 3. The changes of blood water content (83.1-84.3%) and cardiac water content (77.5-78.3 gm/100gm WT) were observed. 4. In control animals myocardial potassium levels which averaged 30.2 mEq/100 gmDT rose significantly to 40.3 mEq/100 gmDT in shock (P<0.01), while moderate decreases in sodium(16.3-14.3 mEq/100 gmDT) were observed in shock. 5. The calculated transmembrane resting potential of left ventricular muscle of control animals averaged 95 mV, while rabbits in shock averaged 77 mV. (P <0.01). The findings of this experiment do not correspond with the conclusions that myocardial depression seems to be the cause of irreversible hemorrhagic shock, because the excitability of heart muscle is elevated. From the point of view that the lowered transmembrane resting potential, the cause of death in terminal stage of irreversible hemorrhagic shock may be ventricular fibrillation. It can't be said, however, that the lowered transmembrane resting potential is responsible for the transition from reversible to irreversible hemorrhagic shock. The marked increase in blood glucose suggested that glycogenolysis in the liver is favorably active in shock.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.4
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• pp.281-287
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• 2016

In this paper, we propose a novel compact surveillance throwing robot which has an omnidirectional shock absorption mechanism and an active control part of wheel treads to stabilize the dynamic posture of a miniature sphere type throwing robot. This throwing robot, which weighs 1.14kg and is 110mm in height, is designed in a spherical shape to be easily grabbed for throwing. Also, the omnidirectional shock absorbing aspect is designed using several leaf springs connected with inner and outer wheels. The wheel treads control part consists of a link mechanism. Through the field experiments, this robot is validated to withstand higher than 17Ns of omnidirectional impulse and increase the stabilized max speed three times from 11 rad/s to 33rad/s by increasing wheel treads.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.85-89
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• 2003

The difference in the thermotolerance between Saccharomyces cerevisiae KNU5377 and ATCC24858 was compared by assaying the amounts of trehalose accumulated under growth and heat shock conditions. Both strains exhibited similar trehalose accumulation during the growth period, but an intrinsic thermotolerance was much higher in KNU5377 than in the control strain. This result implied that some strain-specific characteristics of KNU5377, other than trehalose accumulation, primarily were responsible fur its higher intrinsic thermotolerance. Heat shock at $43^{\circ}C$ for 90 min to the exponentially growing cells resulted in the maximum level of trehalose In both strains. Trehalose accumulated at least twice more in KNU5377 by the heat shock than in the control, due to the maintenance of its neutral trehalase activity even after the heat shock. Consequently, the Increase of acquired thermotolerance in both strains correlated with an increase in the trehalose content in each strain. In conclusion, KNU5377 exhibited a well-modulated trehalose-related mechanism to accumulate more trehalose by means of maintaining neutral trehalase activity after heat shock than the control strain, thereby contributing to its acquired thermotolerance.

• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.102-112
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• 1998

Shock absorber has a great influence on the performance of the vehicle(ride comfort, manipulation, noise, vibration, turning, stability). Therefore, in this study we consider theoretically about general damper, variable damping oil damper, the control of vehicle Characteristics for the suspension, and undesirable phenomenon. And we measured the vibration/noise characteristics of shock absorber for the real car experimentation, strain change, and noise characteristics of shock absorber using experimental equipment. The study of domestic company and research institute on the vehicle shock absorber is active, but that of basis is not. So we think that they should be accomplished actively. Therefore, this paper will develop theoretical system on the vibration/noise characteristics of shock absorber by theoretical consideration and experimental result analysis of dynamic characteristics of shock absorber that were accomplished in this study. Then we will use it as the optimistic design data for shock absorber development.

• Journal of KSNVE
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• v.11 no.1
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• pp.41-48
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• 2001

This paper presents vibration control performance of a passenger vehicle featuring magneto-rheological (MR) suspension units. As a first step, a cylindrical shock absorber is designed and manufactured on the basis of Bingham Property of a commercially available MR fluid. After verifying that the damping force of the shock absorber can be controlled by the intensity of magnetic field(or input current), it is applied to a full-car model. An optimal controller is then formulated to effectively suppress unwanted vibration of the vehicle system. The control performances are evaluated via hardware-in-the-loop simulation(HILS), and presented in both time and frequency domains.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.9 no.3
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• pp.533-540
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• 2019

This study investigated the effect of extracorporeal shock wave therapy on nerve regeneration in nerve injured rats. In this study, we used 30 male Sprague-Dawley rats weighing 230-280g and 6 weeks old. Study groups were divided into two groups using a random sampling method: experimental group (n=15) treated with extracorporeal shock wave after sciatic nerve injury and control group (n=15) treated without extracorporeal shock wave after sciatic nerve injury. In this study, extracorporeal shock wave therapy equipment (OPTIMUS, SALUS TALENT 3, Korea) was used to apply extracorporeal shock wave therapy and applied to the sciatic nerve crush area of the right hind limb using low intensity. We measured the stance time and stride distance of the affected side using dartfish software. There was a statistically significant difference in the change of stance time and stride distance of the affected side between the experimental group using extracorporeal shock wave therapy and the control group without extracorporeal shock wave treatment. In conclusion, extracorporeal shock wave therapy has a positive effect on nerve regeneration.