• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.3
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• pp.327-339
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• 1986

In this paper, a hardware compiler for symbolic description language(SDL) is proposed for logic design automation. Lexical analysis is performed for SDL which describes the behavioral characteristics of a digital system at the register transfer level by the proposed algorithm I. The algorithm I is proposed to get the expressions for the control unit and for the data transfer unit. In order to obtain the network description language(NDL) expressions equivalent to gate-level logic circuits, another algorithm, the the algorithm II, is proposed. Syntax analysis for the data formed by the algorithm I is also Performed using circuit elements such as D Flip-Flop, 2-input AND, OR, and NOT gates. This SDL hardware compiler is implemented in the programming language C(VAX-11/750(UNIX)), and its efficiency is shown by experiments with logic design examples.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.4
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• pp.575-584
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• 2017

It is suggested the circuit network to analyze the time response of control system. And it is analyzed the interrelation for classical control and modern control by the transfer function and the state equation. Without complicated integration of state transition equation, it is suggested to possible time response by combining the state transition matrix and the transfer function. A source program is coded to display the time response according to the unit-step and the sinusoidal input. Transient response is analyzed in the unit-step input and phase difference between current and voltage is analyzed in sinusoidal input. As writing the suggested contents in transient response or state-space analysis, it is improved the understanding for control engineering and ability for system design.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.82.2-82.2
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• 2011

A channel design which is closely related with the mass transport overpotential is one of the most important procedures to optimize the whole fuel cell performance. In this study, three dimensional results of a numerical study for gas distribution in channels of a molten carbonate fuel cell (MCFC) unit cell for a 1kW class stack was presented. The relationship between the fuel and air distribution in the anode and cathode channels of the unit cell and the electric performance was observed. A charge balance model in the electrodes and the electrolyte coupled with a heat transfer model and a fluid flow model in the porous electrodes and the channels was solved for the mass, momentum, energy, species and charge conservation. The electronic and ionic charge balance in the anode and cathode current feeders, the electrolyte and GDEs were solved for using Ohm's law, while Butler-Volmer charge transfer kinetics described the charge transfer current density. The material transport was described by the diffusion and convection equations and Navier-Stokes equations govern the flow in the open channel. It was assumed that heat is produced by the electrochemical reactions and joule heating due to the electrical currents.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.3
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• pp.599-604
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• 2008

An experimental study has been performed to investigate the air-side capacity and pressure drop of the fin-tube heat exchanger for a fan coil unit under a cooling condition. The experimental data of five kinds of slit fin-tube heat exchangers were measured using an air-enthalpy calorimeter and a constant temperature water bath. Cooling capacities at the air and water rating flow rates were larger at the lower inlet water temperature. With increasing the water flow rate, the cooling capacity increased at the constant rate. Under the lower inlet water temperature, since the condensate was generated more on the fin-tube surface, the air-side pressure drop of the heat exchanger was larger.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.959-965
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• 2024

The High Temperature Test Unit (HTTU) was an experimental set-up to conduct separate and integral effects tests of the Pebble Bed Modular Reactor (PBMR) core. The annular core consisted of a randomly packed bed of uniform spheres. Natural convection tests using both nitrogen and helium, and forced convection tests using nitrogen, were conducted. The maximum material temperature achieved during forced convection testing was 1200 ℃. This paper presents the numerical analysis of the flow and temperature distribution for a forced convection test using 3D CFD as well as a 1D systems-CFD computer code. Several modelling approaches are possible, ranging from a fully explicit to a semi-implicit method that relies on correlations of their associated phenomena. For the comparison between codes, the analysis was performed using a porous media approach, where the conduction and radiative heat transfer were lumped together as an effective thermal conductivity and the convective heat transfer was correlated between the solid and gas phases. The results from both codes were validated against the experimental measurements. Favourable results were obtained, in particular by the systems-CFD code with minimal computational and time requirements.

• Hip & pelvis
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• v.34 no.3
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• pp.177-184
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• 2022

This study aimed to analyse the initial results of five patients with symptomatic osteochondral lesions (OCL) and femoroacetabular impingement (FAI) who were treated successfully with osteochondral autologous transfer (OAT) and femoral neck osteochondroplasty (OCP) through surgical dislocation of the hip. Five patients with FAI and OCL of the femoral head who underwent surgery between 2015-2018 were studied retrospectively. All patients had a grade IV OCL, and the median defect size was 2 cm2 (interquartile range [IQR], 2-2). At the final follow-up, the modified Harris hip score showed a median value of 94 (IQR, 91-95) (P=0.04). Pain evaluation using the visual analogue scale showed a median value of 1 (IQR, 1-2) (P=0.04). Adequate graft union and healthy formation of the chondral surface were observed by magnetic resonance imaging. Although the procedure is demanding, the combination of OAT and femoral neck OCP appears to be an effective alternative in young patients.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.10
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• pp.817-824
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• 2015

Experiments were carried out to investigate the flow and mass transfer characteristics of an orifice nozzle. Measurements of primary and suction flow rates, dissolved oxygen concentration, and electric power were obtained. Vertically injected mixed-jet images were captured by a direct visualization technique with a high speed camera unit. The mass ratio, volumetric mass transfer coefficient, and mass transfer performance were calculated using the measured data. As the primary flow pressure increases, the mass ratio decreases slightly, while the volumetric mass transfer coefficient and electric power increase. As the primary flow pressure increases and the mass ratio decreases, the mass transfer rate increases because of the fine bubbles and wider distribution of the bubbles.

• Journal of Korean Academy of Nursing
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• v.44 no.2
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• pp.219-227
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• 2014

Purpose: To assess whether the Modified Early Warning Score (MEWS) predicts the need for intensive care unit (ICU) transfer for patients with severe sepsis or septic shock admitted to general wards. Methods: A retrospective chart review of 100 general ward patients with severe sepsis or septic shock was implemented. Clinical information and MEWS according to point of time between ICU group and general ward group were reviewed. Data were analyzed using multivariate logistic regression and the area under the receiver operating characteristic curves with SPSS/WIN 18.0 program. Results: Thirty-eight ICU patients and sixty-two general ward patients were included. In multivariate logistic regression, MEWS (odds ratio [OR] 2.02, 95% confidence interval [CI] 1.43-2.85), lactic acid (OR 1.83, 95% CI 1.22-2.73) and diastolic blood pressure (OR 0.89, 95% CI 0.80-1.00) were predictive of ICU transfer. The sensitivity and the specificity of MEWS used with cut-off value of six were 89.5% and 67.7% for ICU transfer. Conclusion: MEWS is an effective predictor of ICU transfer. A clinical algorithm could be created to respond to high MEWS and intervene with appropriate changes in clinical management.

• Journal of electromagnetic engineering and science
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• v.11 no.3
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• pp.166-173
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• 2011

In this paper, we implemented and analyzed a wireless power transfer (WPT) system with a CSPR topology. CSPR refers to constant current source, series resonance circuit topology of a transmitting coil, parallel resonance circuit topology of a receiving coil, and pure resistive loading. The transmitting coil is coupled by a magnetic field to the receiving coil without wire. Although the electromotive force (emf) is small (about 4.5V), the voltage on load resistor is 148V, because a parallel resonance scheme was adopted for the receiving coil. The implemented WPT system is designed to be able to transfer up to 1 kW power and can operate a LED TV. Before the implementation, the EMF reduction mechanism based on the use of ferrite and a metal shield box was confirmed by an EM simulation and we found that the EMF can be suppressed dramatically by using this shield. The operating frequency of the implemented WPT system is 30.7kHz and the air gap between two coils is 150mm. The power transferred to the load resistor is 147W and the real power transfer efficiency is 66.4 %.

• Journal of the Korean Institute of Gas
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• v.15 no.2
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• pp.82-87
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• 2011

Heat transfer oils are used in applications such as heating systems of chemical plant, refinery heat exchange systems, gas plant process, injection molding systems, and pulp and paper processing. These oils are extremely stable and resistance to thermal and oxidative degradation. In the event of a spill or accidental release of heat transfer oils, it can be ignite easily when there is an ignition source. This paper discusses the flammability and thermal stabilities of new and used oils. The flammability of the oils are assessed by measuring changes in flash point and auto ignition temperature. The thermal stability of oils are evaluated by the thermal screening unit ($TS^u$) and the differential scanning calorimeter (DSC). From the experimental results, it is suggested to give fire hazard characteristics to safe precautions for the proper use and treatment of heat transfer oils.