• 한국연소학회:학술대회논문집
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• 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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• pp.251-255
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• 2015

Unsteady Shock-Induced Combustion has been studied for the past few decades since it is considered as one of the potential ways to reach supersonic flights. Experimental observations of Unsteady SIC were observed as early as 1960's. But Lehr was the first to report in detail the mechanisms of Shock-Induced Combustion experimentally. Numerical Studies on SIC were helpful in explaining the insight into the oscillatory behaviour in the mid 90's to early 2000's. Detailed reaction mechanisms is required to prediction the SIC flowfield more in detail. However at that time, very few reaction mechanisms on hydrogen-oxidation were reported. In the last decade, various number of hydrogen reaction mechanisms were reported. In this study, an attempt has been made to analyze the effect of various reaction mechanisms in an unsteady mode of Shock-Induced Combustion.

• 한국분말재료학회지
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• 제15권2호
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• pp.101-106
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• 2008

The objective of the present study is to investigate the increase in the functional characteristics of a substrate by the formation of a thin coating layer. Thin coating layers of $Ti_5Si_3$ have high potential because $Ti_5Si_3$ exhibits high hardness. Shock induced reaction synthesis is an attractive fabrication technique to synthesize uniform coating layer by controlling the shock wave. Ti and Si powders to form $Ti_5Si_3$ using shock induced reaction synthesis, were mixed using high-energy ball mill into small scale. The positive effect of this technique is highly functional coating layer on the substrate due to ultra fine substructure, which improves the bonding strength. These materials are in great demand as heat resisting, structural and corrosion resistant materials. Thin $Ti_5Si_3$ coating layer was successfully recovered and showed high Vickers' hardness (Hv=1183). Characterization studies on microstructure revealed a fairly uniform distribution of powders with good interfacial integrity between the powders and the substrate.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.444-449
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• 2001

A numerical parametric study is conducted to simulate shock-induced combustion with a variation in freestream conditions. A steady combustion front is established if the freestream Mach number is above the Chapman-Jouguet speed of the mixture. On the other, an unsteady reaction front is established if the the freestream Mach number is below or at the Chapman-Jouguet speed of the mixture. The three cases have been simulated for Machs 4.18, 5.11, and 6.46 with a projectile diameter of 15 mm. Machs 4.18 and 5.11 shows an unsteady reaction front, whereas Mach 6.46 represents a steady reaction front. Thus Chapman-Jouguet speed is one of deciding factor for the instabilities to trigger.

• International Journal of Aeronautical and Space Sciences
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• 제1권1호
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• pp.21-28
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• 2000

The flowfield of hypersonic shock-shock interaction has been simulated using a two-dimensional Navier-Stokes code based on AUSMPW+ scheme. AUSMPW+ scheme is a new hybrid flux splitting scheme, which is improved by introducing pressure-based weight functions to eliminate the typical drawbacks of AUSM-type schemes, such as non-monotone pressure solutions. To study the real gas effects, three different gas models are taken into account in the present paper: perfect gas, equilibrium flow and non equilibrium flow. It has been investigated how each gas model influences on the peak surface loading, such as wall pressure and wall heat transfer, and unsteady structure of flowfield in the region of shock-shock interaction. With the results, the value of peak pressure is not sensitive to the real gas effects nor to the wall catalyticity. However, the value of peak heat transfer rates is affected by the real gas effects and the wall catalyticity. Also, the structure of the flowfield changes drastically in the presence of real gas effects.

• 국제지역연구
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• 제22권4호
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• pp.3-18
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• 2018

본 연구에서는 변동성반응가설에 입각한 T-GARCH 모형을 사용하여 최근 24년간의 일별 주식시장 수익률 자료를 바탕으로 OECD 29개 회원국들의 자본시장 충격반응도를 분석하였다. 연구모형에 사용한 독립변수로는 글로벌 금융위기의 진원지이며 세계시장 점유율도 가장 큰 미국시장 수익률을 사용하였다. 그 결과 OECD 회원국 중 미국으로부터의 수익률 전이효과가 가장 큰 나라는 프랑스, 핀란드, 멕시코의 순으로 나타났고 모형의 설명력은 캐나다, 멕시코, 프랑스 순으로 나타났다. 변동성반응가설에 입각한 충격반응의 크기로는 독일, 칠레, 스위스, 덴마크의 순으로 크게 나타났고 하락시장 충격에 대한 반응은 그리스, 영국, 호주, 일본의 순으로 크게 나타났다. NAFTA에 속한 캐나다와 멕시코는 예상대로 미국시장으로부터의 수익률 전이와 설명력이 크게 나타났으나 충격반응의 정도는 OECD 회원국들 중 하위권에 속하는 것으로 나타나 인근 지역의 국가들간의 더 큰 영향력이 존재한다는 중력이론을 지지하지 않았다. 한편, 2008년 미국발 글로벌 금융위기기간만을 고려한 소표본 분석을 통해서는 전체 기간과는 달리 북미 3국의 충격반응도가 서로 일관성이 없는 대신 유럽 각국의 충격반응도는 더욱 강하게 나타남으로써 미국발 충격이 주로 유럽지역에 미쳤음을 입증해 주었다.

• Journal of Veterinary Science
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• 제24권6호
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• pp.77.1-77.7
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• 2023

Antibiotics are known to be able to cause hypersensitivity reactions through various mechanisms. We present a case of drug-induced immune thrombocytopenia (DITP) and anaphylactic shock occurring simultaneously in a dog after the administration of two classes of antibiotics, namely trimethoprim-sulfamethoxazole (TMP-SMX) and amoxicillin-clavulanate (AMC). The patient recovered completely from DITP on discontinuation of TMP-SMX and the anaphylactic shock caused by AMC was treated with intensive care. DITP is a rare adverse drug reaction (ADR), and anaphylactic shock is a life-threatening ADR. This is the first case report of a dog manifesting two types of hypersensitivity reactions caused by two antibiotics.

• 대한수학회논문집
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• 제10권3호
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• pp.767-781
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• 1995

In this paper we present computation of a reflected shock in the hypersonic flow of air with chemical reactions. We consider two dimensional steady inviscid hypersonic flow of air around bodies including chemical reaction effects. At a high Mach number, a strong shock is formed in front of the body when a wedge is placed against the flow. In front of the shock, temperature and pressure increase greatly and the flow is in nonequilibrium state. If the shock hits a wall, then a reflected shock is formed in the nonequilibrium flow region. Behind this reflected shock, the temperature and pressure are very high. We carry out the computation of the reflected shock and the flow behind it. The jump conditions at the reflected shock are presented. A technique combining smooth transforms of domain and implicit difference methods is used to overcome numerical difficulties associated with the lack of resolution behind the shock and near the body.

• 한국운동역학회지
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• 제34권2호
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• pp.81-92
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• 2024

Objective: The purpose of this study was to analyze the impact acceleration, shock attenuation and biomechanical variables at various running speed. Method: 20 subjects (height: 176.15 ± 0.63 cm, weight: 70.95 ± 9.77 kg, age: 27.00 ± 4.65 yrs.) participated in this study. The subjects ran at four different speeds (2.5 m/s, 3.0 m/s, 3.5 m/s, 4.0 m/s). Three-dimensional accelerometers were attached to the distal tibia, sternum and head. Gait parameters, biomechanical variables (lower extremity joint angle, moment, power and ground reaction force) and acceleration variables (impact acceleration, shock attenuation) were calculated during the stance phase of the running. Repeated measures ANOVA was used with an alpha level of .05. Results: In gait parameters, decreased stance time, increasing stride length and stride frequency with increasing running speed. And at swing time 2.5 m/s and 4.0 m/s was decreased compared to 3.0 m/s and 3.5 m/s. Biomechanical variables statistically increased with increasing running speed except knee joint ROM, maximum ankle dorsiflexion moment, and maximum hip flexion moment. In acceleration variables as the running speed increased (2.5 m/s to 4.0 m/s), the impact acceleration on the distal tibia increased by more than twice, while the sternum and head increased by approximately 1.1 and 1.2 times, respectively. And shock attenuation (tibia to head) increased as the running speed increased. Conclusion: When running speed increases, the magnitude and increasing rate of sternum and head acceleration are lower compared to the proximal tibia, while shock attenuation increases. This suggests that limiting trunk movement and increasing lower limb movement effectively reduce impact from increased shock. However, to fully understand the body's mechanism for reducing shock, further studies are needed with accelerometers attached to more segments to examine their relationship with kinematic variables.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2001년도 제17회 학술발표회 논문초록집
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• pp.43-47
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• 2001

A numerical parametric study is conducted to simulate shock-induced combustion with a variation in freestream conditions. The analysis is limited to inviscid flow and includes chmical nonequilibrium. A steady combustion front is established if the freestream Mach number is above the Chapman-Jouguet speed of the mixture. On the other, an unsteady reaction fi:ont is established if the freestream Mach number is below or at the Chapman-Jouguet speed of the mixture. The three cases have been simulated for Machs 4.18, 5.11, and 6.46 with a projectile diameter of 15 mm. Machs 4.18 and 5.11 shows an unsteady reaction front, whereas Mach 6.46 represents a steady reaction front. Thus Chapman-Jouguet speed is one of deciding factor for the instabilities to trigger. The instabilities of the chemical front with a variation of projectiles diameters will be investigated.

• 대한치과마취과학회지
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• 제14권4호
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• pp.243-250
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• 2014

Generalized anaphylaxis is a most dramatic and acutely life-threatening allergic reaction and may cause death within a few minutes. Differential diagnosis of anaphylaxis is made by clinical signs, such as, mental change, respiratory distress, hypotension, hypoglycemia, urticaria and angioedema. Especially, insulin reaction, myocardial infarction and vasovagal syncope are considered as differential diagnosis. In cases of fatal anaphylaxis, respiratory and cardiovascular disturbances predominate and are evident early in the reaction. This is a case report of the intensive care of anaphylactic shock after intravenous injection of the penicillin in a old medically compromised patient with the maxillary osteonecrosis. The anaphylactic shock symptoms, such as, unconsciousness, respiratory disorder, no pulsation on carotid artery and cardiopulmonary arrest are occurred in intravenous injection of augmentin 1.2 g after the skin test. In spite of immediate emergency cares, such as intravenous injection of epinephrine, endotracheal intubation, cardiopulmonary resuscitation, and continuous intensive care, the patient is expired in 58 hours after anaphylactic shock attack.