• Journal of the Semiconductor & Display Technology
• /
• v.5 no.1 s.14
• /
• pp.13-16
• /
• 2006

AIN thin films were prepared on amorphous glass and $SiO_2(1{\mu}m)/Si(100)$ substrate by the facing targets sputtering (FTS) apparatus, which can provide high density plasma, a high deposition rate at a low working gas pressure. The AIN thin films were deposited at a different nitrogen gas flow rate ($1.0{\sim}0.3$) and other sputtering parameters were fixed such as sputtering power of 200w, working pressures of 1mTorr and AIN thin film thickness of 800 nm, respectively. The thickness and crystallographic characteristics of AIN thin films as a function of $N_2$ gas flow rate $[N_2/(N_2+Ar)]$ were measured by $\alpha$-step and an X-ray diffraction (XRD) instrument. And the c-axis preferred orientations were evaluated by rocking curve. In the results, we could prepared the AIN thin film with c-axis preferred orientation of about $5^{\circ}$ on substrate temperature R.T. at nitrogen gas flow rate 0.7.

• Journal of Korean Academy of Fundamentals of Nursing
• /
• v.17 no.4
• /
• pp.531-538
• /
• 2010

Purpose: This study was done to identify the effects of Qi hand reflexology on autonomic nerve activity in patients admitted to hospital. Method: A non-equivalent control group and quasi-experimental research with pre/post test design were used and 59 patients on a medical ward were assigned to either the experimental group (32) or the control group (27). The study variables included vital signs, autonomic nerve activities (ALF (absolute low frequency), AHF (absolute high frequency), nLF (normalized low frequency), nHF (normalized high frequency), SDNN (standard deviation of all normal-normal intervals)) and were evaluated using the QECG-3 system. The experimental group was treated with Qi hand reflexology for 10 minutes per day, for 3days. Results: Skin temperature and systolic blood pressure in the experimental decreased with treatment. ALF, AHF and SDNN for the experimental group increased with regulating proportion (nLF: nHF=6:4) and a significant difference between the groups was observed. Conclusion: The results indicated that application of Qi hand reflexology for patients in the hospital is effective in regulating the autonomic nervous system activation. Implication of finding should be useful for future research.

• Journal of Korea Foundry Society
• /
• v.37 no.2
• /
• pp.38-44
• /
• 2017

Given that the conventional extrusion of high-strength Al alloys such as 7075 aluminum alloys is difficult due to their very low extrudability as compared to that of 6061 aluminum alloys, thixo-extrusion can be used to obtain a high-strength material easily at a lower extrusion pressure as compared to conventional extrusion. In this study, hot- and thixo-extruded 7075 aluminum alloys are prepared by a vertical forward extrusion process and their microstructures, hardness levels, and compressive properties are investigated. Hot-extruded alloy bars are assessed to obtain a microstructure elongated in the extrusion direction, whereas with thixo-extruded alloy bars, it was possible to obtain a microstructure having fine and equiaxed grains by dynamic recrystallization. The resulting isotropy and improved formability at the hot deformation temperature of the thixo-extruded alloy were attributed to the fine and equiaxed grains formed by the thixo-extrusion process.

• Journal of the Korean Applied Science and Technology
• /
• v.30 no.1
• /
• pp.9-15
• /
• 2013

A new process for the synthesis of polyphenylcarbosilane (PPCS) via thermal rearrangement of polymethylphenylsilane (PMPS) in supercritical cyclohexane was proposed and investigated at reaction temperatures of $380-420^{\circ}C$, reaction times of 1-2 h, and a pressure of 15 MPa. The structure, molecular weight, and molecular weight distribution of the product were characterized by FT-IR, Si-NMR, and GPC. The ceramic yield was also measured by TGA analysis. High-quality PPCS with high molecular weight and ceramic yield can be synthesized via a supercritical process. Furthermore, this process, when compared to the conventional method, tends to moderate the reaction conditions such as reaction temperature and time. It is concluded that thermal rearrangement in supercritical fluid is an efficient and viable process in terms of the resulting yield, efficiency, and reaction time compared with those of the conventional PCS production process.

• Preventive Nutrition and Food Science
• /
• v.20 no.2
• /
• pp.102-109
• /
• 2015

In order to investigate the thermal degradation of glucose and maltose solutions after high temperature and high pressure (HTHP) treatment, the samples were treated at temperatures of 110, 120, 130, 140, and $150^{\circ}C$ for 1, 2, 3, 4, and 5 h in an apparatus for HTHP treatment. Glucose and maltose solutions (20% w/w) were prepared by weighing glucose and maltose and adding distilled water in the desired proportion. Chromaticity, pH, organic acids, 5-hydroxymethylfurfural (HMF), free sugar contents, electron donating ability (EDA), and ascorbic acid equivalent antioxidant capacity (AEAC) were evaluated. With increasing heating temperatures and times, the L-, a-, and b-values decreased. The pH and free sugar contents decreased, and organic acids and HMF contents increased with greater temperatures and times. EDA (%) and the AEAC of the heating sugars increased with the increases in temperatures and times.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2012.05a
• /
• pp.41-42
• /
• 2012

High temperature / high pressure spray equipment using a conventional method, unlike spray polyurea adjustable pot life and yellowing caused by UV light and chemicals do not occur, or discoloration of Self-Leveling Type of rugged hand-polyurea resin for technology development is underway. This new concept of polyurea resin roller, brush, airless spray, and they installed easily using the unfamiliar labor, and curing time of approximately four hours to gain control of the glass because it is Pot. Construction, but does not like the spray polyurea resin, compared to the existing degradation of the adhesion strength is concerned. In this study, Self-Leveling Type Manual of polyurea resin adhesion strength of target deterioration Let's minimize problems by reviewing existing domestic and infrastructure long-term durability for long life of the facility is to obtain.

• The KSFM Journal of Fluid Machinery
• /
• v.17 no.4
• /
• pp.76-80
• /
• 2014

PFA fluoropolymer lined technology revolutionized ball valve development and design decades ago and continues to be pivotal for many products and valve solutions in diverse industries and applications, such as chemical process, semiconductor/LCD manufacturing processes, pharmaceutical and others. Because of the extreme operating conditions such as high-temperature (${\sim}120^{\circ}C$) and high-pressure (~10 bar), the reliability of the valve is very important for minimizing in-line leakage and fugitive emissions of strong corrosive chemicals (hydrochloric acid, hydrofluoric acid, nitric acid, etc.) transported through the lines. In this study, we investigated the flow characteristics with flow coefficient in a PFA lined ball valve for different opening degrees using CFD analyses. The results should be the guidance for a new PFA lined ball valve design that will incorporate all the acclaimed and demonstrated benefits of the current design approaches.

• Journal of Power System Engineering
• /
• v.14 no.3
• /
• pp.5-12
• /
• 2010

The purpose of this study is to analyze heterogeneous distribution of branch-like structure at downstream region of inner spray. The previous many studies about diesel spray structure have yet stayed in the analysis of 2-D structure, and there are very few of informations which are concerned with 3-D analysis of the structure. The heterogeneous distribution of droplets in inner spray affects the mixture formation of diesel spray, and also the combustion characteristics of the diesel engines. Therefore, in order to investigate 3-D structure of evaporative spray the laser beam of 2-D plane was used in this study. Liquid fuel was injected from a single-hole nozzle (l/d=5) into a constant-volume vessel under high pressure and temperature in order to visualize the spray phenomena. The incident laser beam was offset on the central axis. From the images analysis taken by offset of laser beam, we examine formation mechanism of heterogeneous distribution by vortex flow at the downstream of the diesel spray. As the experimental results, the branch-like structure formed heterogeneous distribution of the droplets consists of high concentration of vapor phase in the periphery of droplets and spray tip of branch-like structure. Also the 3-D spatial structure of the evaporative diesel spray can be verified by images obtained from 2-D measurement methods.

• Tribology and Lubricants
• /
• v.24 no.6
• /
• pp.362-367
• /
• 2008

Tubes in nuclear steam generators are held up by supports because the tubes are long and slender. Fluid flows of high-pressure and high-temperature in the tubes cause oscillating motions between tubes and supports. This is called as FIV (flow induced vibration), which causes fretting wear in contact parts of tube-support. The fretting wear of tube-support can threaten the safety of nuclear power plant. The tube and support materials were Inconel 690 and STS 409. The wear tests were conducted in various environments, which are in water without flow, in flowing water and in flowing water with air. The results showed that the flow of water influenced on the wear-life of tube. The wear-life of tube decreased in water flow as compared with wear-life in stationary water.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.11a
• /
• pp.230-236
• /
• 2001

We developed a built-in sensor bearing to measure the rotor motion of a rolling piston type compressor for the air conditioner. Because of needs for the high efficiency and long life span of compressor, and the usage of alternative refrigerants, the operating condition of the compressor becomes more severe. The accurate measurement of the rotor motion of the compressor can contribute greatly to the design and analysis of the hydrodynamic bearing. However, it is difficult to measure accurately the shaft behavior of small compressor because of the small space for the sensor mount, high temperature and pressure of compressor, oil mixed with refrigerant, and electromagnetic noise of the motor. To overcome these difficulties, we develop the cylindrical capacitive sensor that is built in the hydrodynamic bearing and calibrate the built-in sensor bearing indirectly through measuring the oil relative permittivity. We measured the rotor motion as well as suction and discharge pressures in various conditions. The several experimental results show that the developed built-in sensor bearing can measure the rotor motion not only in steady state but also in transient state.