• Journal of the Korean Home Economics Association
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• v.38 no.1
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• pp.171-183
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• 2000

The purposes of this study were to identify the needs for the employer-supported day care service and to analyze the factors related to the needs for the day care service of the married employees. KLFI(1995)'s National data were used and three Logistic models and one Catmod model were employed to analyse the effects of the independent variables on the needs for the day care service. The results of this study were as follows: First, half of employed workers needed the employer-supported child care service. Second, they preferred the day care center near their residential area than in their work site. Third, according to their age, type of occupation, and their difficulties for the childcare and household work, employed men and women needs on site day care differently. Finally, their needs for the expenditure of duty care service differed by their age, sex, and occupation, and their levels of difficulties for the childcare and household work. These findings suggest that duty care service for the employed man and woman are supported diversely according to their needs and preferences.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.242-247
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• 2009

In this paper, we investigate interference between short-range radiocommunication devices (SRDs) with frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS) methods when they are in the same frequency bands. In order to analyze interference from unwanted emission of SRD with DSSS to that of FHSS, Monte-Carlo (MC) simulation method is employed and interference probabilities are calculated. We simulate interference scenarios in accordance with several duty cycles and bandwidths. It is also assumed that the propagation model is free space The effect of distance between interfering transmitter and victim receiver is analyzed and bit error rate (BER) is simulated. From the interference analysis results, it is shown that duty cycle affects compatibility more than bandwidth does. Also, we can make sure of the separation distance which satisfies BER criterion when there are only one interfering transmitter and multiple interfering transmitters.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.4
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• pp.65-69
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• 2001

Research on the development of CNG dedicated engine that has important meaning both as a clean fuel and an alterna- tive energy to reduce the exhaust emission from diesel engine are actively going on these days. In this study, in order to present the direction and application of CNG engine, we tested the CNG engine performance experimented by changing the parameters such as ignition timing, equivalent ratio. The engine performance experimented by changing the parameters such as ignition timing, equivalent ratio. The engine performance and exhaust emission were measured by engine performance model at maximum load condition with increasing the rpm in the range of 1,000∼2,200rpm. Also, the testing engine was heavy-duty CNG dedicated engine with displacement of 11,050cc.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.3
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• pp.59-65
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• 1999

To reduce the particulate matter and nitrogen oxides from diesel engine, many studies are proceeding and being accomplished practically. In this situation, LNG engine has important meaning as a clean fuel and alternative energy. In this reason, we try to understand the property of LNG fuel and predict the performance with using LNG engine simulation program and practical test. It could help to lead and apply practically LNG engine was studied in performance and other parameter related with engine performance and compared with current diesel engine. The simulation program was proved to be good in describing the experimental result. This means current heavy duty vehicle could be modified to LNG engine.

• International Journal of Aeronautical and Space Sciences
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• v.1 no.2
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• pp.30-42
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• 2000

On-orbit thermal environment test of KOMPSAT was performed in early 1999. An analysis of the test data are addressed in this paper. For the thermal-environmental simulation of spacecraft bus, an artificial heating through the radiator zones and onto some critical heat-dissipating electronic boxes was made by Absorbed-heat Flux Method. Test data obtained in terms of temperature history were reduced into flight heater duty cycles and converted into the total electrical power required for spacecraft thermal control. Verification result of flight heaters dedicated to the bus thermal control is presented. Additionally, an exhaustive heating-control process for maintaining the spacecraft thermally safe and for realistic simulation of the orbital-thermal environment during the test are graphically shown. Qualitative suggestions to post-test model correlation are given in consequency of the analysis.

• Journal of Energy Engineering
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• v.28 no.4
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• pp.13-18
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• 2019

The high energy penalty in amine-based post-combustion CO₂ capture process is hampering its industrial scale application. An advanced process is designed by intensive heat integration within the conventional process to reduce the stripper duty. The study presents the technical feasibility for stripper duty reduction by intensive heat integration in CO₂ capture process. A rigorous rate-based model has been used in Aspen Plus® to simulate conventional and advanced process for a 300 MW coal-based power plant. Several design and operational parameters like split ratio, stripper inter-heater location and flowrate were studied to find the optimum values. The results show that advanced configuration with heat integration can reduces the stripper heat by 14%.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.101-107
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• 2005

In this paper, optimized operating parameters were found using multi-dimensional engine simulation software (KIVA-3V) and micro-genetic algorithm for heavy duty diesel engine. The engine operating condition considered was at 1,737 rev/min and 57 % load. Engine simulation model was validated using an engine equipped with a high pressure electronic unit injector (HEUI) system. Three important parameters were used for the optimization - boost pressure, EGR rate and start of injection timing. Numerical optimization identified HCCI-like combustion characteristics showing significant improvements for the soot and $NO_X$ emissions. The optimized soot and $NO_X$ emissions were reduced to 0.005 g/kW-hr and 1.33 g/kW-hr, respectively. Moreover, the optimum results met EPA 2007 mandates at the operating point considered.

• Journal of Pharmaceutical Investigation
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• v.37 no.6
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• pp.365-368
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• 2007

The primary aim of this study was to investigate the enhancement effect of low-frequency ultrasound on skin permeation. In vitro permeation experiments were performed using Franz modified diffusion cells with ketoprofen as model drug. The effect of various ultrasound factors-ultrasound application mode (continuous mode and discontinuous mode), ultrasound intensity (0.26 $W/cm^2$, and 0.29 $W/cm^2$) and duty cycle (3%, 16%, 50%, and 83%) were studied. The highest permeation was observed at 0.29 $W/cm^2$ intensity, 50% duty cycle, and discontinuous mode. The result suggested the feasibility of low frequency ultrasound application for the phonophoretic transdermal drug delivery system.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.4_1
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• pp.411-419
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• 2021

In this study, IGBT_Total_Loss and DIODE_Total_Loss were used to analyze the slope of the junction temperature for each section for temperature and duty variables in order to simply calculate the junction temperature of the power semiconductor (IGBT). As a result of the calculation, IGBT_Max_Junction_Temp and DIODE_Max_Junction_Temp form a proportional relationship with temperature for each duty. This simulation data shows that the power loss of a power semiconductor is calculated in a complex manner according to the current dependence index, voltage dependence index, and temperature coefficient. By applying the slope for each condition and section, the junction temperature of the power semiconductor can be calculated simply.

• Korean Chemical Engineering Research
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• v.43 no.4
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• pp.474-481
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• 2005

In this study, modeling and optimization work were performed to obtain nearly pure anhydrous ethanol from aqueous ethanol mixtures using benzene as an entrainer. NRTL liquid activity coefficient model was adopted for phase equilibrium calculations and PRO/II with PROVISION 6.01, a commercial process simulator, was used to simulate the azeotropic distillation process. We used the total reboiler heat duties as an objective function and the concentration of ethanol at concentrator top as a manipulated variable. As a result, 76 mole percent of ethanol at concentrator top gave an optimum value which minimized the total reboiler heat duties of three distillation columns.