• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.241-243
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• 1991

The LB technique is one of the most, powerful fabricating methods of organic ultra thin film, which deposits a monolayer film in molecular level onto the surface of the substrate. In order to fabricate the LB film with optimal condition, we have to deposite monolayer film at optimum depositing pressure. which is dependent on the kind of deposit materials. ${\pi}-A$ curve is one of the most important, criteria to determine the optimum pressure. In this paper, we obtained that the optimum pressure is $20{\sim}50(mN/m)$ from ${\pi}-A$ curve of the stearic acid. In our experiments, it was known that LB ultra thin film is deposited beat at 30(mN/m) by checking the characteristics of LB film.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.1
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• pp.1-7
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• 2003

The optimal design for the shape of MIL-S-46119 ring obturator under the high pressure using parameter stud:』 on the stress analysis considering effects of design variable is presented, and it is compared to experimental results. The trends of parametric study are in good agreement with the experimental results. The more thickness the higher stress. The more taper the higher stress. And maximum stress of circumferential surface is larger than maximum stress of forward surface. The design variable!; are such as thickness, taper, radius of shape of the obturator. In order to optimize the shape of obturation ring, the weight is maximized subject to maximum stress of the obturator within allowable stress. The design constraints are geometric elements of design variables.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.73-81
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• 2003

In case of hollow cylinder extrusion using porthole die, the effects of extrusion parameters-temperature, the speed of extrusion, the shape of the die and mandrel-on metal flow in porthole die extrusion of aluminum have been investigated. However, there have been few studies about condenser tube extruded by porthole die. Original metal flow of condenser tube by porthole die extrusion is similar to hollow cylinder extrusion but the estimation of metal flow for extrusion parameters is different. For example, variation of chamber length in hollow extrusion only affects the welding pressure, however, the welding chamber length in condenser tube extrusion influences to the welding pressure as well as the deflection of mandrel. This study was designed to evaluate metal flow, welding pressure, extrusion load, tendency of mandrel deflection according to angular variation in the bottom of chamber in porthole die. Estimation was carried out using finite element method in as non-steady state. Analytical results can provide useful information the optimal design of porthole die.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.2
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• pp.129-138
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• 2017

The subjective experiments on professional musicians using the four channel real-time convolution system were conducted to investigate the effect of reverberant sound pressure level ($L_{rev}$) for stage acoustics. The strength of $L_{rev}$ was changed to 2 dB steps to investigate the optimal strength for ease of performance and the subjective questionnaire survey was conducted to investigate the effect of subjective factor by $L_{rev}$. From the experimental results, a specific strength of $L_{rev}$ is related to ease of music performance. Loudness and directivity are highly correlated.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.5 no.1
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• pp.20-24
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• 2009

There is extensive tubing pipe in the nuclear power plant under high temperature and pressure. Erosion and corrosion defects are expected on this tubing pipe due to environmental and mechanical factors. In this study, Guided Ultrasonic Wave technique was applied to detect defects. The technique explores the advantages of the Guided Ultrasonic Wave method that inspects along the wall of the pipe and can travel long distances, providing rapid collection of data. This paper presents a case study of the Guided Ultrasonic Wave testing of 3/8" tubing pipe. This study offers to understand detected signals through correlation between amplitude and depth of defects.

• Journal of Korean Academy of Nursing
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• v.27 no.3
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• pp.503-509
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• 1997

This study was undertaken to identify optimal head elevation and position in the care of the neurosurgical patient with a cerebral aneurysm. The effects of 0°. 15° and 30° head elevation and three positions (supine, side tying position opposite to the operation site, and side tying position on the same side as the operation site) on ICP was studied in fourteen neurosurgical patients with cerebral aneurysms. The results are as follows : 1. The mean intracranial pressure was significantly lower when the patient's head was elevated at 30° as compared to 0° and 15°. 2. The mean intracranial pressure was significantly lower when the patient was positioned in the supine as compared to side tying position opposite to the operation site and side tying position on the same side as the operation site. The data indicate that head elevation to 30° and the supine position reduce ICP in neurosurgical patients with cerebral aneurysm.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.11
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• pp.508-511
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• 2003

In this paper, electrical characteristics of inductively coupled plasma in an electrodeless fluorescent lamp were investigated using a Langmuir probe with a variation of argon gas pressure. The RF output was applied in the range of 5 ∼ 50 (W) at 13.56 (MHz). The internal plasma voltage of the chamber and the probe current were measured while varying the supply voltage to the Langmuir probe in the range of -100 (V) ∼+100 (V). When the pressure of argon gas was increased, electric current was decreased. There was a significant electric current increase from l0W to 30 〔W〕. Also, when the RF power was increased, electron density was increase. This implies that this method can be used to find an optimal RF rower for efficient light illumination in an electrodeless fluorescent lamp.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.199-202
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• 2006

The objective of this study is to propose methods of controlling the wake behind a sphere for drag reduction using the suboptimal control theory and surrogate management framework, respectively. The Reynolds numbers considered is 300 at which the base flow is unsteady planar symmetric. Given the cost function defined as the square of the difference between the target pressure (potential-flow pressure) and real flow pressure on the sphere surface, the suboptimal control makes the flow steady axisymmetric and produces drag reduction. Based on the actuation profile from the suboptimal control, the optimal wavy actuation profile is obtained using the surrogate management framework and produces drag reduction.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.4
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• pp.81-85
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• 2007

A safety valve is used for protecting the pressure vessel and facilities by discharging the operating fluid into the valve from the accident when the pressure is over the designated value. The fluid is sulfurous acid and nitric acid. etc. in the semi-conductor assembly line. Thus the valve elements material must be acid resistance. Teflon, which is used generally as inner parts of a valve, tends to easily sticks to sliding surface by thermal expansion under high temperature. Some studies are performed to change teflon to another material and shape to have a better fluidity under the condition. The analysis of the thermal expansion is conducted by commercial FEM software to improve the problems. Boundary conditions were temperature and load in this study. From the analysis, the thermal expansion of stainless steel is verified to be lower than that of teflon under high temperature. Thus coupled teflon/stainless steel-made valve is applied to assembly line without danger due to thermal expansion.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.5
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• pp.94-101
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• 2013

Injection molding process is one of the most important methods to produce plastic parts with high efficiency and low cost. The objective of this study is to implement the best plastic injection molding process for LED TV speaker frame. Moldflow analysis and simulation of plastic injection molding process were carried out in order to predict optimal modeling operation conditions and then injection molded part was produced various type of resin temperature, filling time and injection pressure variation. the result was that the best injection molding condition is set as 60bar pressure, 2sec filling time and $310^{\circ}C$ degree. The study result would be useful to variety of plastic injection molding process.