• 전기학회논문지
• /
• 제60권2호
• /
• pp.357-361
• /
• 2011

The terminal current in voltage driven systems is an essential role for characterizing the pattern of electric discharge such as corona, breakdown, etc. Until now, to evaluate this terminal current, Sato's equation has been widely used in areas of high voltage and plasma discharge. Basically Sato's equation was derived by using the energy balance equation and its final form described physical meaning explicitly. To give more general abilities in Sato's equation, we present a generalized approach by directly using the Poynting's theorem incorporating the finite element method. When the magnetic field effect or the time-dependent voltage source is considered, this generalized energy method can be easily applicable to those problems with any dielectric media such as gas, fluid, and solid. As an alternative approach, the integral Ohm's law resulting in small numerical errors has an ability to be applied to multi-port systems. To test the generalized energy method and integral Ohm's law, first, the results from two prosed methods were compared to those from Sato's approach and an analytic solution in parallel plane electrodes. After verification, the generalized method was applied to the tip-sphere electrodes for evaluating the terminal current with three carriers and the Fowler-Nordheim field emission condition. From these results, we concluded that the generalized energy method can be a consistent technique for evaluating the discharge current with various dielectric materials or large magnetic field.

• 한국전기전자재료학회논문지
• /
• 제24권9호
• /
• pp.701-709
• /
• 2011

In semiconductor wafer fabrication, etching is one of the most critical processes, by which a material layer is selectively removed. Because of difficulty to correct a mistake caused by over etching, it is critical that etch should be performed correctly. This paper proposes a new approach for etch endpoint detection of small open area wafers. The traditional endpoint detection technique uses a few manually selected wavelengths, which are adequate for large open areas. As the integrated circuit devices continue to shrink in geometry and increase in device density, detecting the endpoint for small open areas presents a serious challenge to process engineers. In this work, a high-resolution optical emission spectroscopy (OES) sensor is used to provide the necessary sensitivity for detecting subtle endpoint signal. Partial Least Squares (PLS) method is used to analyze the OES data which reduces dimension of the data and increases gap between classes. Support Vector Machine (SVM) is employed to detect endpoint using the data after PLS. SVM classifies normal etching state and after endpoint state. Two data sets from OES are used in training PLS and SVM. The other data sets are used to test the performance of the model. The results show that the trained PLS and SVM hybrid algorithm model detects endpoint accurately.

• 분석과학
• /
• 제10권1호
• /
• pp.35-42
• /
• 1997

Barium titanate 및 PZT와 같은 세라믹 축전물질의 분석을 위해 고압 산분해법을 이용한 시료 전처리 기술을 연구하였다. 질산이나 증류수를 첨가하고 염산의 농도를 변화시키면서, 이들 시료의 정량분석을 유도결합 플라즈마 방출분광법에 의해 수행하였다. 분석 결과를 보면 Ba, Mn, Zn, Si 등 대부분의 원소들은 염산의 농도에 영향을 받지 않으나, Nb와 Zr은 이에 민감한 것으로 밝혀졌다. 그러나 분해시간은 상대적으로 분석 결과에 거의 영향을 미치지 않았다. Nb의 경우에는 가장 좋은 분석 결과를 얻기 위해 염산과 증류수의 비가 3:1(v / v) 보다는 더 진해야 함을 알았다. 또한 Pb의 분석에 있어서 염산과 질산의 혼산을 사용하는 경우보다 붉은 염산만을 사용하였을 경우에 더 좋은 분석 결과를 나타내었다.

• The Korean Journal of Physiology and Pharmacology
• /
• 제6권5호
• /
• pp.255-260
• /
• 2002

The effects of intracellular and extracellular pH on the inwardly rectifying $K^+$ (IRK) channel of the bovine aortic endothelial cells (BAECs) were examined using whole-cell patch-clamp technique. The IRK current, efficiently blocked by $Ba^{2+}\;(200{\mu}M),$ is the most prominent membrane current in BAECs, which mainly determines the resting membrane potential. The expression of Kir2.1 was observed in BAECs using reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Intracellular alkalinization, elicited by the extracellular substitution of NaCl with $NH_4Cl$ (30 mM), significantly augmented the amplitude of IRK current. On the contrary, the amplitude of IRK current was attenuated by the Na-acetate (30 mM)-induced intracellular acidification. The changes in extracellular pH also closely modulated the amplitude of IRK current, which was decreased to $40.2{\pm}1.3%$ of control upon switching the extracellular pH to 4.0 from 7.4. The extracellular pH value for half-maximal inhibition (pK) of IRK current was 5.11. These results demonstrate that the activity of IRK channel in BAECs, probably Kir2.1, was suppressed by proton at both sides of plasma membrane.

• The Korean Journal of Physiology and Pharmacology
• /
• 제4권1호
• /
• pp.41-46
• /
• 2000

Using fluorescence polarization of 12-(9-anthroyloxy)stearic acid (12-AS) and 2-(9-anthroyloxy)stearic acid (2-AS), we evaluated the differential effects of local anesthetics on differential rotational rate between the surface (in carbon number 2 and its surroundings including the head group) and the hydrocarbon interior (in carbon number 12 and its surroundings) of the outer monolayer of the total lipid fraction liposome extracted from synaptosomal plasma membrane vesicles. The anisotropy (r) values for the hydrocarbon interior and the surface region of the liposome outer monolayer were $0.078{\pm}0.001$ and $0.114{\pm}0.001,$ respectively. This means that the rate of rotational mobility in the hydrocarbon interior is faster than that of the surface region. In a dose-dependent manner, the local anesthetics decreased the anisotropy of 12-AS in the hydrocarbon interior of the liposome outer monolayer but increased the anisotropy of 2-AS in the surface region of the monolayer. These results indicate that local anesthetics have significant disordering effects on the hydrocarbon interior but have significant ordering effects on the surface region of the liposome outer monolayer.

• 한국표면공학회지
• /
• 제38권3호
• /
• pp.106-111
• /
• 2005

Ternary Ti-B-C coatings were synthesized on WC-Co and Si wafers substrates by a PECVD technique using a gaseous mixture of $TiCl_4,\;BCl_3,\;CH_4,\;Ar,\;and\; H_2$. The effects of deposition variables such as substrate temperature, gas ratio, $R_x=[BCl_3/(CH_4+BCl_3)]$ on the microstructure and mechanical properties of Ti-B-C coatings were investigated. From our instrumental analyses, the synthesized Ti-B-C coatings was confirmed to be composites consisting of nanocrystallites TiC, quasi-amorphous TiB2, and amorphous carbon at low boron content, on the contrary, nanocrystallites $TiB_2$, quasi-amorphous TiC, and amorphous carbon at relatively high boron content. The microhardness of the Ti-B-C coatings increased from $\~23 GPa$ of TiC to $\~38 GPa$ of $Ti_{0.33}B_{0.55}C_{0.11}$ coatings with increasing the boron content. The $Ti_{0.33}B_{0.55}C_{0.11}$ coatings showed lower average friction coefficient of 0.45, in addition, it showed relatively better wear behavior compared to other binary coatings of $TiB_2$ and TiC. The microstruture and microhardness value of Ti-B-C coatings were largely depend on the deposition temperature.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2007년도 추계학술대회 논문집
• /
• pp.380-381
• /
• 2007

This paper reports on the deposition conditions and properties of ITO films used as electrode layer in a organic light emitting diodes on a PET substrate. The deposition technique employed was specially designed roll-to-roll sputtering. The oxide was deposited at room temperature in an argon and oxygen plasma on a transparent conducting ITO layer on a PET film. The influence of deposition parameters such as DC power, working pressure and oxygen partial pressure has been investigated, in order to obtain the best compromise between a high deposition rate and adequate electro-optical properties. Electrical and optical properties of ITO films were analyzed by Hall measurement examinations with van der pauw geometry at room temperature and UV/Vis spectrometer analysis, respectively. In addition, the structural properties and surface smoothness were measured by x-ray diffraction and scaning electron microscopy, respectively. From optimized ITO films grown by roll-to-roll sputter system, good electrical$(6.44{\times}10^{-4}\;{\Omega}-cm)$ and optical(above 86 % at 550 nm) properties were obtained. Also, the ITO films exhibited amorphous structure and very flat surface beacause of low deposition temperature.

• 한국전기전자재료학회논문지
• /
• 제22권6호
• /
• pp.470-475
• /
• 2009

We deposited $Al_2O_3$ thin films on GaN by remote plasma atomic layer deposition (RPALD) technique, trimethylaluminum(TMA) and oxygen were used as precursors, at fixed process condition, the number of cycle were changed. Growth rate per cycle was $1.2\;{\AA}$/cycle. and Growth rate was in proportion to a number of cycle, the GaN MIS capacitors that $Al_2O_3$ thin film were deposited above 12 nm, have excellent electrical properties, a low electrical leakage current density(${\sim}10^{-10}\;A/cm^2$ at 1.5 MV), but below 12 nm, we can see the degradation of the leakage current density. After post deposition annealing, Dielectric constant was estimated by 1 MHz high-frequency C-V method, it was varied with the anealing temperature from 6.9 at no post anealed to 7.6 at $800^{\circ}C$, and we can see a improvement of the leakage current density and breakdown voltage by post deposition anealing below $700^{\circ}C$, but, after anealed at $800^{\circ}C$, we can see the degradation of the leakage current density and breakdown voltage.

• Journal of Chest Surgery
• /
• 제2권2호
• /
• pp.155-166
• /
• 1969

Heterotopic abdominal homograft of canine heart was carried out in 20 pairs of dogs. Of these 12 cases were subjected as a control and 8 were subjected to immunosuppressive group. The dosage of immunosuppressive agent was 5mg/kg/day of Imuran [Azathioprine] for 3 days preoperatively, 10mg/kg on operative day and 5mg/kg/day postoperatively. For reducing the metabolic demand, the donor heart was preserved in 4degree heparinized saline solution for approximately I4 minutes. In the most of the cases, transplantation was performed with the technique of end-to-side aorto-aortic anastomosis and end-to-side pulmonary artery-inferior vena cava anastomosis at the infrarenal portion. Five out of 20 grafted dogs were survived more than one day. The longest survived 18 days in the control group and survive more than 60 days in the treated group. The survival cases were 3 out of 8[37. 5%] in the group of dogs treated with lmuran and 2`out of 12 [16.6%] in the group of non-treated. A prominent gross findings of the grafted heart was a minimal to moderate degree of dilatation of the heart with or without thrombosis in the cardiac chambers and/or anastomotic site. The case number 10, 15, and 19 showed moderate hypertrophy in grossly. The microscopic findings were as follows; 1. There were early hypersensitive histologic reactions such as interstitial edema, cellular infiltrations and early degenerative changes in the myocardium in the cases of 3 hour survival. 2. In the cases of more than 6 hours survival, organizing thrombosis of myocardial vessels, vasculitis,myocardial necrosis and lymphocyte, plasma cell, round cell infiltrations were noted. In the cases of more than 12 hours survival, the degree of these histologic changes especially in the non-treated group were more intensified than in the treated. 3. In the cases which survived more than one day, so called homograft specific histologic changes were milder in the immunosuppressive group compared with the control. 4. All the host hearts showed no evidence of pathologic findings histologically. Among the homologous canine cardiac transplantation tissue reaction, was milder and suvival time longer in the group treated with immunosuppressive drug.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2009년도 제38회 동계학술대회 초록집
• /
• pp.356-356
• /
• 2010

Tribological behaviors of the hard film on soft substrate system were explored using the hard thin film of diamond-like carbon (DLC) coated the soft polymer of polydimethysiloxane (PDMS). A DLC film with the Young's modulus of 100 GPa was coated on PDMS substrate with Young's modulus of 10 MPa using plasma enhanced chemical vapor deposition (PECVD) technique. The deposition time was varied from 10 sec to 10 min, resulting in nanoscale roughness of wrinkle patterns with the thickness of 20 nm to 510 nm, respectively, at a bias voltage of $400\;V_b$, working pressure 10 mTorr. Nanoscale wrinkle patterns with 20-100 nm in width and 10-30 nm height were formed on DLC coating due to the residual stress in compression and difference in Young's modulus. Nanoscale roughness effect on tribological behaviors was observed by performing a tribo-experiment using the ball-on-disk type tribometer with a steel ball of 6 mm in diameter at the sliding speed of 220 rpm, normal load of 1N and 25% humidity at ambient temperature of $25^{\circ}C$. Friction force were measured with respect to thickness change of coated DLC thin film on PDMS. It was found that with increases the thickness of DLC coating on PDMS, the coefficient of friction decreased by comparison to that of the uncoated PDMS. The wear tracks before and after tribo-test were analyzed using SEM and AFM.