• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.14 no.1
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• pp.24-31
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• 2018

The mechanical design procedure is studied for the PCHE(printed circuit heat exchanger) with electrochemical etched flow channels. The effective heat transfer plates of PCHE are assembled by diffusion bonding to make a module. PCHE is widely used for industrial applications due to its compactness, cost efficiency, and serviceability at high pressure and/or temperature conditions. The limitations and technical barriers of PCHE are investigated for application to nuclear components. Rules for design and fabrication of PCHE are specified in ASME Section VIII but not in ASME Section III of nuclear components. Therefore, the calculation procedure of key dimensions of PCHE is defined based on ASME section VIII. The effective heat transfer region of PCHE is defined by several key dimensions such as the flow channel radius, edge width, wall thickness, and ridge width. The mechanical design procedure of key dimensions was incorporated into a program for easy use in the PCHE design. The effect of assumptions used in the key dimension calculation on stress values is numerically investigated. A comparative analysis is done by comparing finite element analysis results for the semi-circular flow channels with the formula based sizing calculation assuming rectangular cross sections.

• Journal of Korean Clinical Nursing Research
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• v.17 no.2
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• pp.192-203
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• 2011

Purpose: The purpose of this study was to compare the body temperature (BT), blood pressure (BP) and shivering in patients undergoing operation under general anesthesia between the heated humidification circuit tube (HHCT) group and the non-HHCT group. Methods: Data were extracted from the participants' medical records from September 1st to December 30th, 2009. The HHCT group consisted of 50 cases who were applied with heated and humidified gas via a specially designed circuit under general anesthesia. The HHCT which was adjusted at $41^{\circ}C$ was applied from induction of general anesthesia to extubation. In comparison, the non-HHCT group consisted of 50 cases who were applied with gas through standard breathing circuit without heat and humidification. Collected data were analyzed by $x^2$ test, t-test and repeated measures ANOVA. Results: The BT and shivering were significantly different between two groups (p<.001). But the BP was was not signigicantly different between the HHCT group and the non-HHCT group. Conclusion: The application of heated and humidified gases to patients under general anesthesia was effective in preserving the body temperature and reducing the shivering.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.573-576
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• 1995

The realization by many industrial countries that manufacturing is a critical ingredient for attaining economic strength and stability has led to the development of automated systems which were proviously considered as gimmicks. The adaptive skill of the human operator is now being simulated and reproduced by computer that have become more powerful and less expensive. The work presented in this paper forms an investigation of the effects of dynamic viscosity and load of hydraulic oil an pressures with three different circuit(meter-in, meter-out and bleed off). The experimental results showed that pressures increase with an increase in dynamic viscosity and load in bleed off circuit, but there is no variation of pressure in meter-In meter-out circuit.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.2
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• pp.83-90
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• 2018

This paper describes a case study on the design factor analysis of vertical wind tunnel for skydiver's training or experiencing of paradropping exercise in the air. The case study of vertical wind tunnel design is to provide the knowledges on effects of parameter's variation when it is applied to overall or partial duct of tunnel circuit. The analysis of design parameters based on pressure loss are produced one by one through the tunnel components from the flight chamber because the wind tunnel must satisfy the requirement of flight chamber such as flow speed, quality and quantity. Results shows the various effects of parameter variation with pressure loss in the wind tunnel circuit. Pressure loss should be based on the determination of fan and power system which can be selected from market or new design.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2000.11a
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• pp.13-16
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• 2000

This paper describes a design of the external-exciting electronic ballast for 100W high pressure sodium lamp. The ballast is consists of the full-bridge inverter and an external-exciting control circuit. L and C values of an equivalent L-C series resonant circuit are calculated analytically. The electrical output characteristics of the ballast, such as voltage, current etc., are simulated by Pspice. The experimental results from high pressure sodium lamp system with the ballast we developed are shown to be consistent with the simulated results.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.180-180
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• 2012

A microplasma system source based on microwave parallel stripline resonator (MPSR) was developed for the generation of microplasmas in a wide range of pressure from some torr to 760 torr. This source was operated at its resonance frequency that much depends upon not only its discharge gap size but also operated pressure. This paper applied a simple circuit model to analyze the effects of discharge gap size and pressure to resonance frequency and impedance of MPSR in the cases with and without plasma exist inside the discharge gap. In the process of calculating, the conformal mapping method was used to estimate the capacitance of the MPSR. The calculating results by using circuit model agree well with the simulation results that using commercial CST microwave studio software.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.11
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• pp.751-759
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• 2010

A newly developed type PCHE(Printed Circuit Heat Exchanger), which has a longitudinal corrugation flow channel, was fabricated using etching and diffusion bonding to evaluate its hydraulic performance. The pressure drop characteristics obtained from the experimental results are presented and the local friction factors associated with different hydraulic diameters and inclination angles are discussed. The results of a three-dimensional numerical simulation are presented, conducted using commercial CFD(Computational Fluid Dynamics) software at lower Reynolds number range. The numerical results were validated by experimental data obtained from helium gas experimental apparatus. The results of CFD prediction show fairly good agreement with the experimental data.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.4
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• pp.7-13
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• 2001

In this paper, the external-exciting electronic ballast for an 100[W] high pressure sodium lamp using full-bridge inviter is designed. The L-C parallel full-bridge invert circuit for P-SPICE simulation is designed. The values of inductor and capacitor in the proposed equivalent L-C parallel resonant tank circuit are calculated theoretically. Then the ballast for high pressure sodium lamp is implemented using the simulated results. In the experimental results, that is confirmed which the results of implemented ballast are really same with the of simulated one.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.4
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• pp.601-605
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• 2012

The non-controlled closing of High-voltage SF6 gas circuit breaker can cause transient current and overvoltage in the field. The controlled closing technology is an effective way to reduce transient current and voltage, prevent equipment failures, and improve power quality. For the development of controlled closing, it is obviously necessary to determine the withstand voltage between arc contacts of High-voltage SF6 gas circuit breaker in making operation. This paper focuses on decrease of pressure and density of SF6 gas that can affect withstand voltage between arc contacts in making operation. The dielectric strength between arc contacts could be improved by minimizing the decrement of pressure and density of SF6 gas obtained by simulation and test and moreover the rate of decrease of dielectric strength (RDDS) of arc contacts could be foreseen.

• Journal of Drive and Control
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• v.13 no.4
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• pp.31-44
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• 2016

In recent hydraulic actuation systems, conventional hydraulic spool valves with pressure compensators are becoming less popular, after the introduction of the independent metering concept for valves. Within this concept, four valves are needed for actuating a single cylinder. Subsequently, this increases the freedom of controlling both chamber pressures of the cylinder, and it then provides for electronically-controlled pressure compensation facilities. Additionally, this has the potential to save valuable energy. The primary focus of this paper is to develop a new generation of hydraulic circuits using the independent metering valve (IMV). This configuration can function well as a conventional IMV circuit while providing better pressure control. We first describe the working principles of five distinct modes of the proposed IMV system. Then, mathematical models for each working mode are presented. Finally, we present numerical simulations that have been carried out to evaluate the system performance, in comparison with that of the conventional IMV configuration. The simulation results demonstrate that the performance of the new IMV configuration is superior to the conventional IMV system in terms of energy savings.