• Korean Chemical Engineering Research
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• 제58권2호
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• pp.307-312
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• 2020

최근 대기압이하 진공 압력 상태에서 운전되는 유동층 반응기는 진공건조 공정이나 플라즈마 화학증착과 같이 감압 유동화가 요구되기에 관심이 증대되어 왔다. 그러나 대기압 이하에서 운전되는 유동층의 수력학적 특성 연구는 많이 연구되지 않았다. 본 연구에서는 대기압 이하에서 운전하는 유동층의 압력강하를 층내 압력을 1.33 에서 101.3kPa 까지 변화시키며 측정하였다. 유동층의 운전 압력이 진공인 상태에서는 최소유동화속도가 압력이 감소함에 따라 증가하며, 이는 기체 밀도와 평균 자유경로 변화와 같은 slip 흐름에 의한 변화이다. 또한 기존의 상압 상태에서 운전되는 유동층의 최소유동화속도 상관식과 비교함으로써 압력 감소에 따른 slip 흐름의 영향 뚜렷하게 나타남을 가리키는 임계 Knudsen 수를 결정하였다. 이로부터 slip 흐름이 주도하기 시작하는 임계 압력을 실험적으로 결정하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.525-528
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• 2001

ZnO:Al thin film can be used as a transparent conducting oxide(TCO) which has low electric resistivity and high optical transmittance for the front electrode of amorphous silicon solar cells and display devices. This study of electrical, crystallographic and optical properties of Al doped ZnO thin films prepared by Facing Targets Sputtering(FTS), where strong internal magnets were contained in target holders to confine the plasma between the targets, is described. Optimal transmittance and resistivity was obtained by controlling flow rate of $O_2$ gas and substrate temperature. When the $O_2$ gas rate of 0.3 and substrate temperature $200^{\circ}C$, ZnO:Al thin film had strongly oriented c-axis and lower resistivity( < $10^{-4}{\Omega}-cm$ ).

• 한국전기전자재료학회논문지
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• 제17권9호
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• pp.979-982
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• 2004

The ZnO thin films were prepared by the FTS (facing target sputtering) system, which enables to provide high density plasma and a high deposition rate at a low working gas pressure. We introduced the AZO thin film in order to improve the crystallographic properties of ZnO thin film because of the AZO(ZnO:Al) thin film has an equal crystal structure to the ZnO thin film. ZnO/AZO thin films were deposited at a different oxygen gas flow ratio, R.T. 2mTorr working pressure and a 0.8A sputtering current. The film thickness and c-axis preferred orientation of ZnO/AZO/glass thin films were measured by ${\alpha}$-step and an x-ray diffraction (XRD) instrument. In the results, we could prepare the ZnO thin film with c-axis preferred orientation of about 6$^{\circ}$ on substrate temperature R.T. at O$_2$ gas flo rate 0.5.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.151-154
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• 2003

AlN/Al/SiO$_2$/Si thin films for application to FBAR(Film Bulk Acoustic Resonator) devices were prepared by FTS(Facing Targets sputtering system) apparatus which provides a stable discharge at low gas pressures and can deposit high quality thin films because of the substrate located apart from the plasma. The AlN thin films were deposited on a $SiO_2(1{\mu}m)/Si(100)$ substrate using an Al bottom electrode. The process parameters were fixed such as sputering power of 200W, working pressures of 1mTorr and AlN thin film thickness of 800nm, respectively and crytallographic characteristics of AlN thin films were investigated as a function of $N_2$ gas flow rate$[N_2/(N_2+Ar)]$. Thickness of AlN thin films were measured by $\alpha$-step, the crystallographic characteristics and c-axis preferred orientation were evaluated by XRD.

• Biomolecules & Therapeutics
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• 제8권2호
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• pp.132-139
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• 2000

This study was performed far investigation of influence on renal function of idazoxan, $\alpha_{2}$-adrenergic antagonist, using the dog. Idazoxan, when giver. into vein, produced the decrease of urine volume(vol) accompanied with the reduction of free water clearance($C_{H2O}$), amounts of sodium excreted in urine($E_{Na}$), with the increase of potassium excreted in urine($E_{K}$), and so ratios of potassium against sodium($K^{+}/Na^{+}$) were elevated, at this time, greatened reabsorption rate of sodium and diministered that of potassium in renal tubules were appeared. Idazoxan administered into a renal artery elicited the augmentation of vol, glomerular filtration rate(GFR), renal plasma flow(RPF) and no change of filtration fraction(FF) in only ipsilateral kidney, whereas $E_{Na},\;E_{K}\;and\;K^{+}/Na^{+}$ were increased and $C_{H2O}$ was decreased in both control and experimental kidney. Idazoxan given into carotid artery showed partial increased vol, remarkable expanded RPF and unchanged GFR, and so filtration fraction(FF) was markedly reduced. Above results suggest that anti- diuretic action of idazoxan given into vein is mediated by reduction of $C_{H2O}\;and\;E_{Na}$, diuretic action only in the ipsilateral kidney by idazoxan given into a renal artery is caused by hemodynamic improvement through expansion of vas afferens in glomeruli.

• 대한기계학회논문집B
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• 제25권5호
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• pp.666-672
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• 2001

Experiments have been carried out to investigate the evaporation heat transfer characteristics of various tubes on which hydrophilic surface treatment using plasma was employed. Spiral, corrugated and low-finned tubes were selected as test tubes. The evaporator tubes were bundled to form three rows of tubes connected in series, with each row being 400mm long. The results obtained indicate that hydrophilic treated tubes tested exhibit better evaporation heat transfer performance as compared with untreated tubes. It is found that the high wettability of the surface obtained through hydrophilic treatment induces film flow onto the tubes during the evaporation process, while sessile drops are formed on untreated tubes.

• Korea-Australia Rheology Journal
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• 제19권2호
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• pp.61-66
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• 2007

The aggregation characteristics of red blood cells (RBCs) are known as important factors in the microvascular flow system, and increased RBC aggregation has been observed in various pathological diseases, such as thrombosis and myocardial infarction. This paper describes a simple microfluidic device for measuring the RBC aggregation by integrating a microfluidic slit rheometry and laser-backscattering technique. While a decreasing-pressure mechanism was applied to the microfluidic rheometry, a syllectogram (the light intensity versus time) showed an initial increase and a peak caused by the high shear stress-induced disaggregation, immediately followed by a decrease in the light intensity due to RBC aggregation. The critical shear stress (CST) corresponding to the peak intensity was examined as a new index of the RBC aggregation characteristics. The CST of RBCs increased with increasing aggregation-dominating protein (fibrinogen) in the blood plasma. The essential feature of this design was the combination of the rheometric-optic characterization of RBC aggregation with a microfluidic chip, which may potentially allow cell aggregation measurements to be easily carried out in a clinical setting.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2008년도 Proceedings of the Convention
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• pp.103-115
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• 2008

Hemodynamic shear stress, the dragging force generated by blood flow, is known as an anti-atherogenic factor. We tested whether lysyl-tRNA synthetase (KRS) will be utilized as an agent controlling shear-sensing systems. KRS was previously known to be secreted as a pro-inflammatory agent. Here we found that KRS inhibited various shear-stimulated signaling pathways. We further found that KRS binds to detergent-resistant membrane (DRM), indicating that KRS binding molecules exist in DRM, specialized regions of the plasma membrane. DRM plays important roles in a variety of cellular processes and consists of gangliosides, signaling molecules and cytoskeletons. We then determined that KRS was colocalized with integrins ${\alpha}4$, ${\alpha}5$ and $av{\beta}3$. In addition, KRS was shown to be associated with sialic acid, existing at the end of gangliosides. Interestingly, the adherent effect of KRS was inhibited by pretreatment with sialic acid. Moreover, treatment of endothelial cells with neuraminidase appeared to inhibit both the KRS adhesion to endothelial cells and shear-stimulated signaling. In conclusion, KRS is likely to be utilized as a vascular regulator.

• 분석과학
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• 제8권4호
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• pp.487-492
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• 1995

The chemical compositions and pyrolysis characteristics of oil shales and source rocks distributed in the southwestern and southeastern parts of the Korean peninsular have been investigated. In order to compare the results of Korean samples with those of shales giving high oil yields, two Colorado oil shale samples and one Paris source rock samples were also investigated. Chemical compositions of the samples were analysed by means of gravimetry, CHN analysis, X-ray diffraction method, inductively coupled plasma atomic emission spectrometry and atomic absorption spectrometry. A custom made pyrolyser and a Rock-Eval system were used for the pyrolysis studies. Pyrolyses of the samples were carried out by means of a temperature controlling device to $600^{\circ}C$ at a heating rate of $5^{\circ}C/min$ with a helium flow rate of $1200m{\ell}/min$. The results of pyrolysis study indicated that Colorado shale samples belong to type I and all the other samples belong to type II.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2182-2185
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• 1999

In this experimental study we propose the double dielectric barrier discharge(DDBD) reactor to produce as high an electric field as possible. DDBD reactor is designed to remove $NO_x$ at atmospheric pressures from the moving pollution source such as diesel automobile DDBD reactor consisted of two cylinder glass tubes arranged so that the gas flow was directed between the two tubes. Inside of the inner tube was filled with small metal beads and outside of the inner tube was wounded with stainless wire to form the electrode. The outer tube was surrounded by an aluminum foil In this reactor there are three electrodes, i.e. metal bead(C), helical wire(I) and aluminum foil(0). By using DDBD reactor we will report some interesting results of treatment of the gas which is the dilute mixtures of NO in N2. And then we compared thee results with the results of cylinder-wire(CW) which is one of popularly used reactor in non-thermal plasma applications.