• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.223-227
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• 2005

A PCV valve is a part to control the flow rate of Blowby gas in a PCV system. A PCV system re-burns Blowby gas with fuel in a combustion chamber. Some gas enters to a crankcase room through the gap between piston ring and engine cylinder wall. This gas si called 'Blowby gas'. This gas causes many problems. In environmental view, Blowby gas includes about $25\~35\%$ hydrocarbon{HC) of total generated HC in an automobile. Hydrocarbon is a very harmful pollutant element in our life. In mechanical view, Blowby gas has some reaction with lubricant oil of crankcase room. Then, this causes lubricant oil contamination, crankcase corrosion and a decrease fo engine efficiency. Consequently, Blowby gas must be eliminated from a crankcase room. In this study, we simulated internal flow characteristics in a PCV valve according to spool dynamic behavior using local remeshing method And, we programmed our sub routine to simulate a spool dynamic motion. As results, spool dynamic behavior is periodically oscillated by the relationship between fluid force and elastic force of spring. And its magnitude is linearly increased by the differential pressure between inlet and outlet. Also, as spool is largely moved, flow area is suddenly decreased at orifice. For this reason, flow velocity is rapidly decreased by viscous effect.

• 대한수의학회지
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• 제48권2호
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• pp.175-179
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• 2008

Parallux, a solid-phase fluorescence immunoassay (SPFIA) developed for detection antibiotics residue in milk, was applied for analysis of antibiotics in muscle tissue of olive flounder (Paralichthys olivaceus), rockfish (Sebastes schlegeli), and red sea bream (Pagrus major). Fishes were dipped in neomycin 140 mg/ton water, the recommended therapeutic dose, for 24 h. Muscle samples were obtained on 1st, 2nd, 3rd, 4th and 5th day after drug treatment. The concentration of neomycin in muscle was determined using an internal standard (100 ppb as neomycin). The absorbance ratio of sample to internal standard (S/C) was employed as an index to determine the muscle residues in fishes. To investigate the recovery rate, the standard solutions were added to muscle samples to give final concentrations in muscle of 0.2 and 0.5 mg/ml. The recovery rates of all spiked samples were > 85% of the spiked value. Neomycin was detected in muscles of fishes treated after the 1st day of withdrawal period. On the 2nd day after drug treatment, all muscle samples showed negative reaction (S/C ration ${\leq}$ 1.0). The present study showed that the SPFIA can be applied for predicting residues of neomycin in muscle tissues of farmed fishes.

• 천문학회보
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• 제35권2호
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• pp.73.2-73.2
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• 2010

In order to understand internal dynamics of starless cores, molecular line emissions are usually observed. From profiles of the molecular lines, internal motions of starless cores have been deduced using a simple radiative transfer model such as the two-layer model (Myers et al.1996). This brings complexities arising from the chemical evolution. The motivation of this study is to follow the chemical evolution of a starless core that goes through gravitational contraction. For this purpose, we have performed hydrodynamical simulations with a marginally unstable Bonnor-Ebert sphere as an initial condition. We follow the chemical evolution of this core with changing conditions such as the chemical reaction rate at the dust surface and the strength of radiation field that penetrate into the core. At the core center, the molecules suffer from a higher degree of molecular depletion on the dust covered by ice rather than on the bare silicate dust. The stronger radiation field dissociates more molecules at the core envelope. From analysis on the line profile using the two-layer model, we found that the speed of inward motion deduced from the HCN F = 2-1 line adequately traces the true infall speed, when the dust is covered by ice and the core is exposed to the diffuse interstellar radiation field. Under different conditions, the two-layer model significantly underestimate the infall speed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.104-107
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• 2001

In order to investigate the effect of Ge addition to the Cu matrix on the microstructure and the critical current density, four kinds of internal tin processed Nb$_3$Sn strands with pure Cu and Cu 0.2, 0.4, 0.6 wt % Ge alloys were drawn to 0.8 mm diameter. The microstructure and critical current of internal tin processed Nb$_3$Sn wires that were heat treated at temperatures ranging from 68$0^{\circ}C$ to 74$0^{\circ}C$ for 240h were investigated. The Ge addition to the matrix did not make workability worse. A Ge rich layer in the Cu-Ge matrix suppressed the growth of the Nb$_3$Sn layer and promoted grain coarsening. The greater the Ge content in the matrix, the lower the net Jc result after Nb$_3$sn reaction heat treatment. There was no significant variation in Jc observed with heat treatment temperature ranging from 68$0^{\circ}C$ to 74$0^{\circ}C$. The values of AC loss of Ge added wires were decreased to 40 % compare with no addition wire. Low AC loss was due to segregation of Ge rich layer in the Cu-Ge matrix. If Ge added wire with thin Nb filaments were fabricated, slow diffusion rate of Sn would be overcome and decreased AC loss that is weak Point of internal tin method.

• Journal of Veterinary Science
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• 제25권1호
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• pp.1.1-1.15
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• 2024

Background: Axitinib, a potent and selective inhibitor of vascular endothelial growth factor (VEGF) receptor (VEGFR) tyrosine kinase 1,2 and 3, is used in chemotherapy because it inhibits tumor angiogenesis by blocking the VEGF/VEGFR pathway. In veterinary medicine, attempts have been made to apply tyrosine kinase inhibitors with anti-angiogenic effects to tumor patients, but there are no studies on axitinib in canine mammary gland tumors (MGTs). Objectives: This study aimed to confirm the antitumor activity of axitinib in canine mammary gland cell lines. Methods: We treated canine MGT cell lines (CIPp and CIPm) with axitinib and conducted CCK, wound healing, apoptosis, and cell cycle assays. Additionally, we evaluated the expression levels of angiogenesis-associated factors, including VEGFs, PDGF-A, FGF-2, and TGF-β1, using quantitative real-time polymerase chain reaction. Furthermore, we collected canine peripheral blood mononuclear cells (PBMCs), activated them with concanavalin A (ConA) and lipopolysaccharide (LPS), and then treated them with axitinib to investigate changes in viability. Results: When axitinib was administered to CIPp and CIPm, cell viability significantly decreased at 24, 48, and 72 h (p < 0.001), and migration was markedly reduced (6 h, p < 0.05; 12 h, p < 0.005). The apoptosis rate significantly increased (p < 0.01), and the G2/M phase ratio showed a significant increase (p < 0.001). Additionally, there was no significant change in the viability of canine PBMCs treated with LPS and ConA. Conclusion: In this study, we confirmed the antitumor activity of axitinib against canine MGT cell lines. Accordingly, we suggest that axitinib can be applied as a new treatment for patients with canine MGTs.

• 공업화학
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• 제10권5호
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• pp.652-659
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• 1999

메탄을 연료로 한 직접 내부개질형 용융탄산염 연료전지의 anode전극위치에 따른 개질 촉매의 피독 현상을 규명하였다. 수증기-탄소 비를 2.5로 고정시킨 후 운전전압 0.75 V, 전류밀도 $140mA/cm^2$을 유지하면서 24시간 운전중인 연료전지를 정지시키고 anode전극 내, 가스흐름 방향으로 입구, 중간 및 출구 부분에 충전된 촉매를 채취하여 탄소와 전해질 성분인 리튬과 칼륨의 피독 정도를 분석하였고 운전시간 100시간 후, 같은 방법으로 촉매를 분석하였다. 그 결과, 운전시간 24시간 경과 후 촉매의 리튬과 칼륨의 피독량은 입구부에서 0.27 wt%, 중간부에서 0.23 wt% 출구부에서 1.59 wt%로 출구부에 충전된 촉매 피독량이 제일 높았지만 100시간 경과 후 촉매의 피독량은 입구부에서 가장 높았다. 이러한 결과는 직접 내부개질형 연료전지의 성능 모사를 통한 전극 내 위치별 반응속도와 이에 따른 촉매의 역할로 설명이 가능하였다. 전지의 성능 모사 결과 전극 내 메탄-수증기 개질 반응은 입구 부분 30%까지 초기 메탄 유입량의 90%가 반응하여 이 부분에 충전된 촉매가 가장 많이 사용되고 전극반응도 가장 활발하게 일어나 입구부 촉매의 탄소와 전해질 피독량이 높았고 운전 시간에 따른 피독 정도가 가장 빨랐다. 전극 내 출구부는 가장 높은 온도분포를 보이고 있어 상대적으로 전해질 증발이 많아져 운전 초기부터 촉매의 전해질 피독이 빠르게 일어나지만 개질 반응과 전극 반응은 상대적으로 적게 진행되어 촉매의 피독 속도는 크지 않았다.

• 대한기계학회논문집
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• 제19권2호
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• pp.548-558
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• 1995

An experimental investigation has been conducted to study the spray and combustion characteristics using the air-assisted twin fluid atomizer. Axial mean and fluctuating velocity components as well as drop-size distributions in non-reaction spray were measured with a nonintrusive phase doppler technique. Droplet number density distributions were also visualized using high speed CCD camera. Locations of spray and flame boundaries are obtained by direct photographic method. It is confirmed that at the fixed fuel flow rate, the increase of the atomizing air flow causes improvements on both spray and combustion characteristics under stable flame conditions. Internal group combustion modes where flame is located inside the spray boundary are observed to exist in the upstream region of higher droplet number density.

• 한국자동차공학회논문집
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• 제19권6호
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• pp.46-52
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• 2011

Homogeneous charge compression ignition (HCCI) is the best concept able to provide low NOx and PM in diesel engine emissions. This new alternative combustion process is mainly controlled by chemical kinetics in comparison with the conventional combustion in internal combustion engine. However, HCCI engine's operation have an excessive rate of pressure rising during the combustion process. In this study, stratification condition of EGR exhaust gases was used to reduce the pressure rising during the combustion process in HCCI engine. Also, combustion characteristics and emissions characteristics were investigated using the detailed diesel surrogate reaction mechanism.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2003년도 추계학술대회
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• pp.343-350
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• 2003

The best Ppy weight ratio was 7 wt% and the optimal electrode composition ratio was 78 : 17 : 5 wt.% of (MSP-20 : BP-20 =1 : 1), (Super P : Ppy =10 : 7) and P(VdF-co-HFP). Implantation of Ppy as the conducting agents have led to superior electrochemical characteristics because of the low of internal resistance and faradaic capacitance. The result of unit cell with Ppy 7 wt% were as follows: 28.02 Fig of specific capacitance, 1.34 Ω of DC-ESR and 0.36 Ω of AC-ESR. Unit cell showed a good stability up to 200 charge-discharge cycles, retaining 82% of their original capacity at 200 cycles. From the analysis of impedance, the electrodes with Ppy 7 wt% showed low ESR, low charge transfer resistance and quick reaction rate. It was inferred that quick charge-discharge was possible. As compared with the specific capacitance (rectangular shape) of CV, it was also concluded that the specific capacitance originated from thecompound phenomena of the faradaic capacitance by oxidation and reduction of Ppy and the non-faradaic capacitance by adsorption-desorption of activated carbon.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.513-516
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• 2017

화약 기반 소자 (PMD)에서 장기간 보관을 하게 되면 소자 안에 있는 화약이 노화되어 폭발력에 변화가 생기기 때문에, 일정 기간이 지나면 폐기 처분을 하게 된다. 그렇기 때문에 PMD 안에 사용하는 화약은 자발적 혹은 외부적 요인에 대하여 화학적 및 물리적으로 안정해야 한다. 기존에 사용되는 화약으로서 $BKNO_3$과 THPP를 대표적으로 이용하기 때문에, 이 화약들을 기반으로 하여 열역학적 및 속도론적 분석을 실시하였다. Differential scanning calorimeter (DSC)를 이용하여 발열량과 반응속도를 분석하였는데, 그 결과 THPP에서는 열량 차이 및 반응속도에 큰 변화가 보이지 않았다. 추가적으로, 노화에 직접적으로 연관되는 산화막 형성을 확인하기 위하여 XPS 및 TEM-EDS 분석하였는데, 열적 분석 결과와 상응하는 결과로서 산화막이 관측 되지 않았다. 이는 THPP가 장기 안정성 측면에서 가장 유명한 화약이라고 판단 할 수 있다.