• Journal of the Korean Ceramic Society
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• v.42 no.12 s.283
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• pp.854-859
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• 2005

Performance of micro scale intermediate temperature solid oxide fuel cell system has been successfully evaluated by computer simulation based on macro modeling. Two systems were studied in this work. The one is designed that the ceria-based electrolyte placed between composite electrodes and the other is designed that electrodes alternately placed on the electrolyte. The injected gas was composed of hydrogen and air. The polarization curve was obtained through a series of calculations for ohmic loss, activation loss and concentration loss. The calculation of each loss was based on the solving of mathematical model of multi physical-phenomena such as ion conduction, fluid dynamics and diffusion and convection by Finite Element Method (FEM). The performance characteristics of SOFC were quantitatively investigated for various structural parameters such as distance between electrodes and thickness of electrolyte.

• Safety and Health at Work
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• v.14 no.4
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• pp.358-367
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• 2023

Background: This study aimed to develop and assess the psychometric features of the Physical Activity at Workplace Questionnaire (PAWPQ) based on the Social Cognitive Theory (SCT) to evaluate employees' physical activity (PA) behaviors at the workplace. Methods: This psychometric cross-sectional study was conducted on 455 employees working in one of the gas refineries in Iran. The participants were selected using the proportional stratified sampling method in 2019. The data collection tools were a demographic information questionnaire, the short form of the International Physical Activity Questionnaire (IPAQ), and a questionnaire developed based on the SCT, whose psychometric features were confirmed in terms of validity and reliability. Data were analyzed using SPSS₂₂ and AMOS₂₀ software. Results: The first version of PAWPQ-SCT had 74 items. After evaluating content and face validity, nine items were removed. The results of the content validity index (0.98), content validity ratio (0.86), and impact score (3.62) were acceptable for the whole instrument. In exploratory factor analysis, after removing seven items-58-item final version of the scale-six factors could explain 73.54% of the total variance. The results of structural equation modeling showed the acceptable fit of the model into the data (RMSEA = 0.052, CFI = 0.917, NFI = 0.878, TLI = 0.905, IFI = 0.917, CMIN/DF = 2.818). Cronbach's alpha coefficient and Intraclass Correlation were 0.90 and 0.86, respectively. Conclusion: This study confirmed that the psychometric features of the 58-item final version of PAWPQSCT constructs were acceptable in a sample of Iranian employees. This questionnaire can be used as a valid and reliable tool to evaluate Iranian employees' PA behaviors and develop effective educational interventions for workers and managers.

• Korea Journal of Hospital Management
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• v.7 no.4
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• pp.123-151
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• 2002

The objective of this study is to analyze the causal relationship of hospital inpatient's perceived quality, overall satisfaction, service value, and future intention to revisit. To carry out this objective, first we analyzed the dimensions of inpatient care service quality using SERVQUAL scale. The SERVQUAL scale is based on the gap theory, that is, the difference of patients' expectations and the actually received medical care service in hospital. On the basis of this theory, we measured the inpatient's perceived service quality and overall patient satisfaction. Data was gathered from a self-administered questionnaire at a 980 bed university hospital in Inchon City. These questionnaire measuring the service quality were distributed to 250 inpatients. The response rate was 66.4%. A total of 166 questionnaires was finally analyzed. To categorize medical service quality, the factor analysis was performed on 42 items. The reliability and validity of these items was evaluated. Finally to test 6 hypotheses, we analyzed the causal relationship of service quality, overall satisfaction, service value, and intention to revisit through the structural equation modeling(SEM). The major results of this study are as follows. First, the dimension of inpatient service quality was categorized into 7 dimensions, that is, personal caring, communication, access, physical environment, facilities and equipment, cleanliness, appropriateness and health status. Second, the reliability and validity of inpatient service quality items was satisfied. Third, as a result of structural equation modeling, the effect of inpatient's perceived service quality on overall satisfaction, service value, and intention to revisit was statistically significant. And total effect on intention to revisit as the core endogenous variable was perceived service quality(1.100), patient satisfaction(0.006), and service value(0.605).

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.3
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• pp.217-232
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• 2017

An Eulerian-Lagrangian hybrid modeling system to analyze physical and chemical processes during the transport of air parcels was developed. The Backward-tracking Model Analyzer (BMA) was designed to take advantages of both Eulerian and Lagrangian modeling approaches. Simulated trajectories from the National Oceanic and Atmospheric Administration HYSPLIT model were combined with the US Environmental Protection Agency Community Multi-scale Air Quality (CMAQ)-simulated concentrations and additional diagnostic analyses. In this study, we first introduced a generalized methodology to seamlessly match polylines (HYSPLIT) and threedimensional polygons (CMAQ), which enables mass-conservative analyses of physio-chemical processes of transporting air parcels. Two applications of the BMA were conducted: (1) a long-range transport case of pollutant plume across the Yellow Sea using CMAQ Integrated Process Rate analyses, and (2) a domestic circulation of pollutants within (and near) the South Korea based on the sulfate tracking analyzer. The first episode demonstrated a secondary formation of nitrate and ammonium during the transport over the Yellow Sea while sulfate is mostly transported after being formed over the China, and the second episode demonstrated a dominant impact of boundary condition with active sulfate formation from gas-phase oxidation near the Seoul Metropolitan Area.

• The Journal of the Acoustical Society of Korea
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• v.26 no.7
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• pp.328-333
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• 2007

In this paper, we describe characteristics of a movable bridge called the Anjok and propose an improved string model which has delay line controller in physical modeling of the Gayageum. Movable bridge, the Anjok determines the length of vibrating string and transmits the vibration of each string to the body of the Gayageum. We analyze the variations in frequency domain and implement the Anjok model as parametric form using the first-order polynomial fitting in logarithmic scale graph, because the length of string changes fundamental frequency. In order to implement the Anjok model, frequency fitting, tension fitting and frequency fitting using leaky integrator are used. The frequency fitting using leaky integrator has the best results among those. Proposed string model with the Anjok model can represent real tuning system of the real Gayageum and the proposed model could synthesize sounds which is similar to original sounds.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.1
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• pp.105-118
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• 2016

A naval combat system is the system of systems who supports naval indigenous operations by integrating and inter-operating many different kind of weapons, which has characteristics of large scale complex computing system. ROK Navy has been built a blue ocean navy, so that large scale warships are under constructions. However, warship combat system architecture has not been well studied so far in Korea. The paper focuses on current combat system architecture and propose the next generation combat system architecture, which will give the development direction of ROK Navy. In order to complete combat system architecture studies, the system engineering process shall be applied to the study. Moreover, ARENA simulation tool is used for verification of combat system architecture. The system engineering process is as follows: next-generation naval combat system requirement analysis, functional architecture analysis and physical architecture analysis.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1143-1145
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• 2003

Some of satellites such as IKONOS don't provide the orbital elements so that we can’ utilize the physical sensor model. Therefore, Rational Function Model(RFM) which is one of mathematical models could be a feasible solution. In order to improve 3D geopositioning accuracy of IKONOS stereo imagery, Rational Polynomial Coefficients(RPCs) of the RFM need to be updated with Ground Control Points(GCPs). In this paper, a method to improve RPCs of RFM using GCPs and 3D cube is proposed. Firstly, the image coordinates of GCPs are observed. And then, using offset values and scale values of RPC provided, the image coordinates and ground coordinates of 3D cube are initially determined and updated RPCs are computed by the iterative least square method. The proposed method was implemented and analyzed in several cases: different numbers of 3D cube layers and GCPs. The experimental results showed that the proposed method improved the accuracy of RPCs in great amount.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1804-1805
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• 2011

In recent year there has been an increasing interest in the dynamic simulation of complex systems. This study uses a large-scale forty-seventh order fossil fuel power plant. Twenty-three state variables are associated with the physical processes and twenty-four state variables associated with the control system. The plant model is expected to predict all dominant effects in a steady and transient state. In this study, the power plant model is reorganized into four subsystems, each with its controller, and the four connected to each other through a manager, which is a fifth part to the system. The four parts of the unit are the boiler system, steam turbine system, condenser system, and feedwater system.

• Korean Management Science Review
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• v.29 no.2
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• pp.105-125
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• 2012

As medical service industry is transformed into the market centered on consumers, medical service quality patients recognize is emphasized as the powerful means to ensure competitive advantage among hospitals in the fierce medical markets. Many researches have been done on the definition of medical service quality, developing a scale to measure it, patient satisfaction, hospital repurchase and oral transmission intention, but integrated studies have not been done sufficiently on the patient' cognitive emotional aspects. For these research purposes, based on service relation, service quality, physical surroundings, human services, corporate reputation, service value, emotional response, customer satisfaction and repurchase intention, this paper suggests a theoretical modeling composed of hypotheses on the relations of each theoretical variable. In addition, the moderating effect of service relationships is investigated based on the structural equation model.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.83-86
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• 2003

Soil Aquifer Treatment (SAT) is a technique in which secondary- or tertiary-treated wastewater is infiltrated through unsaturated soil and stored in the saturated zone. In SAT, contaminants are removed by physical and biochemical reactions taking place in soils. In this study, a numerical model was developed to predict changes in water quality during SAT operations. The contaminant species considered in the model were ammonium, nitrate, dissolved organic carbon, and dissolved oxygen. The model was calibrated against experimental data obtained from one dimensional soil column tests conducted for 84 days. The calibrated model will be used to find out optimum conditions for the pilot- and regional-scale SAT operations to be scheduled for the next phase of this project.