• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.8
• /
• pp.26-34
• /
• 1997

To develop ultrathin gate oxide for ULSI MOSFETs, for the first time, we fabricated MOS capacitors with 65.angs. thick initial oxide grown by high pressure oxidation (HIPOX) at 700.deg. C in 5 atmosphere $O_{2}$ ambient and then followed by rapid thermal nitridation (RTN) in N$_{2}$O ambient. The dielectric breakdown fields of the initial HIPOX oxide are 13.0 MV/cm and 13.8MV/cm for negative and positive gate bias, respectively and are dependent on nitridation temeprature and time.The lifetimes of the HIPOX oxides extractd by TDDB method are 1.1*10$^{8}$ sec and 3.4 * 10$^{9}$ sec for negative and positive stress current, respectively. The lifetime of the HIPOX oxide dfor negative stress current increases with nitridation time in N$_{2}$O ambient at 1100.deg.C, reaching maximum value stress curretn increases with nitridation time in N$_{2}$O ambient at 1100.deg. C reacing maximum value of 1.2*10$^{9}$ sec for 30 sec of nitridation time, and then subsequently decreases at the longer nitridation time. The lifetimes of the nitrided-HIPOX oxides are longer than 10 years when nitridations are carried out longer than about 50 sec and 12 sec at 1000.deg. C, and 1100.deg. C, respectively.

• The Korean Journal of Physiology
• /
• v.20 no.2
• /
• pp.236-248
• /
• 1986

Alterations of renin-angiotensin system have been suggested as one of the mechanisms increasing arterial blood pressure in experimental and clinical hypertension. But the exact nature of high blood pressure in the early and late phase of renal hypertension is still controversial. To clarify the nature of renin release in both unclipped and clipped kidney of two kidney one clip Goldblatt lypertensive rat, experiments have been done in kidney slices, which were obtained from the rats of 3 and 7 days of operation. Basal rate of renin release was suppressed in unclipped kidney slices compared to clipped kidney Norepinephrine increased renin release from unclipped kidney slices, but not from clipped kidney slices. Suppressions by angiotensin Il and arginine vasopressin of renin release were attenuated in the clipped kidney slices compared to unclipped and sham-operated kidney slices. Increases by verapamil and trifluoperazine of renin release were attenuated in the clipped kidney slices compared to unclipped and sham-operated kidney slices. These results suggest that the negative feedback control mechanism of the renin-angiotensin system by angiotensin Il and arginine vasopressin is attenuated in the clipped kidney of two kidney one clip Goldblatt hypertensive rat, and that one of the altered mechanisms may be caused by certain regulatory changes of intracellular calcium and/or calcium-calmodulin complex in the juxtaglomerular cells.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.49 no.9
• /
• pp.533-540
• /
• 2000

Lightning impulse $(1.2/44[\mus])$ and damped oscillating impulse $(Osc./44[\mus])$ : 0.83[MHz]) breakdown characteristics in sulphur-hexafluoride/nitrogen (SF6-N2) mixtures were investigated. The predischarge currents were observed to clarify the breakdown mechanism. th experiments were carried out under nonuniform electric fields disturbed by a needle-shaped protrusion whose length and diameter are 10[mm] and 1[mm] at total gas pressure up to 0.5[MPa] with nitrogen concentrations varying from 5 to 20[%] in the mixture. The electrical breakdowns of SF6-N2 mixtures for both the positive and negative polarities develop with steplike pulses in leader mechanism and the breakdown voltage -time (V-t) characteristics were affected by the space charge. The voltage-time curves for the negative oscillating impulse voltage were extended over the longer time range. The minimum breakdown voltages for the negative lightning and oscillating impulse voltage were higher than those for the positive ones. in particular the positive breakdown voltages were independent of the gas pressure.

• Journal of the Architectural Institute of Korea Planning & Design
• /
• v.33 no.12
• /
• pp.19-28
• /
• 2017

The purpose of this study is to propose a design methodology to build temporary isolation rooms when infectious diseases suddenly occur in a certain region, such as the case of MERS-Cov in South Korea in 2015. Although most big hospitals usually have isolation rooms, they are expensive and dangerous to run such facilities on normal and typical days. To deal with these problems in this research, shipping containers are chosen as devices used to build the temporary isolation rooms near the original hospital. To do so, firstly, a prototype for the temporary isolation room was designed with the three part modules. The first part is for the medical team; the second part including the isolation rooms is for patients; the third part is for medical selection rooms to test the specimens. Secondly, the plan was compared with the MERS-Cov infection control guidelines. Finally this prototype is applied into the Yong-in Yon-sei severance hospital and then evaluated through a CFD simulation using STAR-CCM+(ver.9.06) for checking infectious bacterium movement in this prototype. The result showed that the prototype is effectively safe for patients tested as negative, patients waiting to be tested, and the medical team.

• Environmental Engineering Research
• /
• v.16 no.1
• /
• pp.29-34
• /
• 2011

The electric charge on a membrane was investigated by analyzing the experimental rejection of various monovalent and divalent ionic solutes. The characteristics of the separation of ionic solutes using various nanofiltration membranes were obtained from an experimental nanofiltration set-up, with a surface area of $40cm^2$ under the operational pressures between 0.25-0.3 MPa. The state of the membrane electric charge was observed using separation coefficients, i.e., the permeation ratio of monovalent to divalent ions. To confirm the state of the membrane charge observed via the separation coefficient, a calculation using the extended Nernst-Planck equation, coupled with the Donnan equilibrium, assuming different electric charge states of the membrane, was compared with the experimental rejection of ionic solutes. The examination of the characteristics of separation using three types of nanofiltration membranes showed that one of the membranes carried a negative/positive double charge density inside, while other two membranes carried either a positive or negative charge density.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.5 no.2
• /
• pp.35-44
• /
• 1999

High negative pressure coefficient is formed in the corner of the bluff body structures. For many curtain wall designers this phenomena is of interest because this high negative pressure coefficient is adopted in structural calculation. The present study is aimed to investigate shedding vortex characteristics of two-dimensional rectangular prism flow. Unsteady calculation by finite difference method based upon SOLA is carried out for three aspect ratios(1:1, 1:2, 1:3) of Re=10$^4$ in viscous incompressible flow within infinite domain. Fluctuation of velocity components at various pick-up points and time variation of drag and lift coefficients are analysed by FFT method to reveal shedding vortex frequency patterns. At aspect ratio 1:1, one primary Strouhal number appears for about all pick-up points. At aspect ratio 1:2, two representative Strouhal numbers are classified by pick-up positions and their flows show two different reattachment patterns. For aspect ratio 1:3, frequency spectrum maintains multiple peaks.

• Journal of ILASS-Korea
• /
• v.3 no.2
• /
• pp.14-23
• /
• 1998

The negative pressure as much as 10's mmHg is demanded at nozzle inside, in case of atomizing the large density molten materials. by conventional air jet nozzle. In this study, suction type fluid nozzle is designed by applying the ejector principle in order to clarify the air flow of nozzle inside, mechanism of liquid suction and liquid film formation. The results of this experimental study areas follows. Suction force of liquid is magnified by using liquid nozzle, and it is able to supply the liquid stable. Negative pressure at nozzle inside is varied by throttle angle of liquid nozzle, position and outer diameter of air jet nozzle, and have a influence on liquid suction quantity and liquid film formation.

• Plant Journal
• /
• v.7 no.2
• /
• pp.30-38
• /
• 2011

The purpose of this paper is to review the understanding of pollution causes in the excitation system and how to solve the problem. The cause of the problem was in-leakage of bearing lubricant oil through the gap between rotor and outer in the air deflector, which was triggered by a negative pressure with respect to the operation of a collector ring fan in the collector house. In order to prevent exciting current transmission equipment pollutant, the reduction of the negative gage pressure of the inside of collector house is required. The protection in-leakage of bearing lubricant oil through the gap between rotor and outer of the air deflector are necessary. The reduction of the inside diameter of air deflector and the expansion of inlet filter of collector house are inevitable.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.03a
• /
• pp.509-516
• /
• 2002

Rainfall-induced landslides in a weathered granite soil slope have mostly relative shallow slip surfaces above the groundwater table The pore-water pressure of soil above the groundwater table is usually negative. This negative pore-water pressure(or matric suction) has been found to make a large contribution to the slope stability. Therefore, the variation of in-situ matric suction profiles with time in a soil slope should be understood. In this study, a field measurement program was carried out from June to August, 2001 to monitor in-situ matric suctions and volumetric water contents in a weathered granite soil slope. The influence of climatic conditions on the variation of in-situ matric suctions could be found to decrease rapidly with depth. It could be found that decrement of matric suction induced by precipitation is affected not only by the amount and duration of rainfalls but also by the initial matric suction just prior to rainstorms. The soil-water characteristic from the field monitoring tends toward the wetting path of SWCC obtained from the laboratory test.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.03a
• /
• pp.743-750
• /
• 2002

Unsaturated soil has a possibility to induce a negative pore water pressure. Until now, saturated soil is mainly focused on the research of soil mechanics. Recently, soil mechanics is researched on two major parts such as saturated and unsaturated soil mechanics. Negative pore water pressure has a non-linear relationship with the water content changes. Soil-water characteristic curves of soil in Korea are not determined. There is no proper characteristic value such as air-entry value and residual water content. In this study, the characteristic curves of reclaimed soil, sand, and weathered granite soil were determined by laboratory tests. Air-entry value and residual water content were determined by fitting methods. Soil-water characteristic curves were estimated based on the particle-size distribution and compared with the laboratory test results. The results of soil-water characteristic curves estimation indicated that Fredlund and Wilson's model is excellent for sand and weathered granite soil. Arya and Paris's model is excellent for reclaimed soil.