• Journal of Satellite, Information and Communications
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• v.5 no.1
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• pp.58-62
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• 2010

This paper presents the effects of RF performance parameters on the Galileo receiver design via simulation after reviewing the requirements of the Galileo receiver structure. At first, we considered the general requirements, structure and characteristics of the Galileo system. Then we designed the Galileo receiver focused on performance requirement of 16 dB C/N which is equal to 15 % Error Vector Magnitude(EVM) by using Advanced Design System(ADS) simulation program. In order to verify the function of Automatic Gain Control(AGC)), we measured the IF output power level by changing the input power level at the front - end of the receiver. We analyzed the performance degradation due to phase noise variations of Local Oscillator(LO) in the Galileo receiver through EVM when the minimum sensitivity level of -127 dBm is applied at the receiver. We also analyzed the performance degradation according to variable Analog-to-Digital Converter(ADC) bits within the Dynamic range, -92 ~ -139 dBm, which has been defined by gain range (-2.5 ~ +42.5 dB) in the AGC operation. The results clearly show that the performance of the Galileo receiver can be improved by increasing ADC bits and reducing Phase Noise of LO.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.670-676
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• 2017

The purpose of this study is to analyze the shipbuilding structure of Hallabong Tangorover ten-day and monthly intervals, to determine whether the shipment control can stabilize and increase the income of Hallabong Tangor farmers by estimating and analyzing the price flexibility function of Hallabong, and to derive the policy implication. Looking at the overall market, the 1% increase in shipment volume indicates that the coefficient of price flexibility varies with time. The largest decline is in late December and early January. The dummy variable indicating the year in which the quality drops somewhat is statistically significant from March to May, and the average of them is -0.337%. This implies a greater importance for quality control and shipment control when quality is worse than good quality. The price flexibility, which indicates price changes due to 1% increase in monthly shipment volume of Hallabong Tangor, varies with time. The coefficient of price flexibility was the highest at -0.46 in December, but prices fell slightly due to quality improvement and the increase in special demand of New Year's demand, which was -0.33% in January, -0.261% in February, -0.307% in March, and -0.318% in April. Since then, the amount of storage has been gradually exhausted, and the price flexibility has fallen slightly to -0.243% in May and -0.236% in June. DUM02, which represents the year when more than 7 days after the New Year holidays are in February is from February to June (+). This indicates that the price decrease due to increase in volume is less than that in January when the New Year is in February. This indicates a greater necessity for shipment control when New Year holidays are in January.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.55-63
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• 2018

This study was intended to identify path structures through pathway analysis with an emphasis on the cognitive elements that influence the acculturative stress of marriage-based immigrant women. The results of the study were designed to establish a foundation for practical measures and policies to support marriage-based immigrant women to adjust their lives in the culture. This study has established research model on the path structure according to the psychological stress theory as to how social support, coping strategy, and acculturative attitude recognized as a cognitive element of marriage-based immigrant women on the acculturative stress and implement practical verification. In addition, control variables for the use of ages, education level, period of marriage, and income level of socio-demographic variables were analyzed. To obtain data for the study, convenience sampling and snowball sampling of marriage-based immigrant women that resided in the area of C and J were conducted simultaneously through surveys and applied to the analysis of 204 cases. Analysis of the path structure of influence of social support, coping strategies, and acculturative attitudes that were perceived as a cognitive element of marriage-based immigrant women influencing acculturative stress revealed that these factors were specifically weighted towards acculturative. Moreover, comprehensive acculturative attitude was identified as a crucial variable reducing the effects of acculturative stress during the acculturative procedures of marriage-based immigrant women. This assumes that establishing and performing policies supporting co-existence of homeland cultures of marriage-based immigrant women and Korean cultures might be an efficient action for dealing with acculturative stress rather than forcing them to adjust to Korean culture.

• Journal of Practical Engineering Education
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• v.14 no.2
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• pp.387-392
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• 2022

To participate in global carbon neutrality, the Korean government is also planning to carry out zero-energy building certification for all buildings by 2030 through the enforcement decree of the 'Green Building Support Act'. Accordingly, the government is providing various projects related to solar power generation, which are relatively close to life. In particular, roof-mounted photovoltaic power generation systems are attracting attention in terms of using unused space to produce energy without destroying the environment, but low power generation efficiency compared to other photovoltaic power generation facilities is pointed out as a disadvantage. Therefore, in this paper, to solve this problem, we propose an efficient solar panel angle variable system through research on the solar panel structure for single-axial solar tracking, and also consider the application environment of the roof-mounted solar power generation system. Suggests measures to prevent damage and secondary damage. In addition, it is judged that it is possible to control the solar panel based on ICT convergence and configure the accident prediction safety system to link the project-based education program.

• Composites Research
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• v.37 no.3
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• pp.219-225
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• 2024

It is essential to develop a light-weight, high-performance structure for the deployable reflector antenna, which is the payload of a reconnaissance satellite, considering launch and orbital operation performance. Among them, the composite main reflector is a key component that constitutes a deployable reflector antenna. In particular, the development of a high-performance main reflector is required to acquire high-quality satellite images after agile attitude control maneuvers during satellite missions. To develop main reflector, the initial design of the main reflector was confirmed considering the structural performance according to the laminate stacking design and material properties of the composite main reflector that constitutes the deployable reflector antenna. Based on the initial design, four types of composite main reflectors were manufactured with the variable for manufacturing process. As variables for manufacturing process, the curing process of the composite structure, the application of adhesive film between the carbon fiber composite sheet and the honeycomb core, and the venting path inside the sandwich composite were selected. After manufacture main reflector, weight measurement, non-destructive testing(NDT), surface error measurement, and modal test were performed on the four types of main reflectors produced. By selecting a manufacturing process that does not apply adhesive film and includes venting path, for a composite main reflector with light weight and structural performance, we developed and verified a main reflector that can be applied to the SAR(Synthetic Aperture Rader) satellite.

• The Journal of the Korea Contents Association
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• v.13 no.8
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• pp.314-323
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• 2013

This study analyzed the relationship between the level of hospital caseloads and length of stay for the delivery patients. The differences of hospital caseloads were measured by the Internal Herfindahl Index, which measured the concentration of delivery patient in a hospital. And the structure variables of hospitals such as the number of bed, the number of treatment, and the number of doctors and nurses per 100 beds were included as control variables. And average length of stay of delivery patients was used as the dependent variable. Concentration status of delivery patients was measured in two models: (1) first model represents the concentration level of delivery patient in all hospital patients, (2) second model represents the concentration level of delivery patient in all obstetrics and gynecology patients. In regression analysis, patient concentration index was not statistically significant in explaining the variation of average length of stay in two models. But the number of delivery patients and number of beds were statistically significant. The number of delivery patient variable showed negative regression coefficient with average length of stay and the number of beds showed positive coefficient with average length of stay. This study result indicated that the volume of delivery patients in a hospital will play a significant role in reducing the length of stay of delivery patients. Patient volume could contribute in improving the efficiency of patient care in a hospital.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.91-103
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• 2022

Purpose: After COVID-19, changes in the educational ecosystem take place and fire service academy education system have shifted from face-to-face into non fact-to-face. So, the educational effect of fire officials is decreased and the satisfaction level is also decreased. In this study, we want to examine the current status of non-face-to-face real-time remote education and supplement the problems to improve the educational methods, the educational environment, etc. Method: This study is an independent variable that affects non-face-to-face real-time remote education, consisting of education system environment, self-efficacy of computers, contents (education contents, structure, design, etc.), and proper interaction. A dependent variable was selected with satisfaction for non-face-to-face real-time remote education. In addition, it was selected and analyzed as an active property of learning motivation and learning attitude as control variables. Result: The better the content and the more active the learning motivation and the attitude toward learning, the higher the satisfaction of non-face-to-face real-time remote education, and the more active the learning motivation and the attitude toward learning, the more positive the computer self-efficacy and the satisfaction of learning Conclusion: In order to increase the satisfaction of non-face-to-face real-time education due to COVID-19, education designers or professors need to provide non-face-to-face education contents that can increase the aggressiveness of their learning motivation and learning attitude, and to increase the satisfaction of education for learners by increasing computer self-efficacy through pre-education of non-face-to-face education systems.

• Journal of the Korea Safety Management & Science
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• v.15 no.3
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• pp.151-161
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• 2013

This paper proposes a strategic model of linkage between productivity metrics and financial accounting metrics to properly evaluate the financial effect of TPM activities and the business performance. This linkage strategy provides a connection tool for clear communication between factory-level and headquarters that the metrics proposed by this paper ultimately improves a quality of support from the management by receiving the factors required for productivity activities in the practical field. This factor includes such as equipment, raw materials and labors. Here, we propose that chain reaction models using break down structure of productivity metrics and financial metrics enhance the knowledge sharing of KPI (Key Performance Indicator) which generally tend to create oversimplified communication between management in headquarters and employees in the practical fields. The productivity metrics include OEE(Overall Equipment Effectiveness) of TPM (Total Productive Maintenance), OLE (Overall Labor Effectiveness) of PAC(Performance and Analysis and Control) activities, and OYE (Overall Yield Effectiveness) of TMM(Total Material Management) activities. The financial accounting metrics include ROE(Return on Equity), ROA(Return on Asset), and AVR(Added-Value Rate). The suggested chain reaction model selects the financial metrics as initial stage and branch down until final stage of productivity metrics. When demand exceeds supply, an ideal speed rate, the lean OEE strategy can be initially applied to reduce the gap between the demand and supply, then apply variable costing to estimate correct amount of operating profit. In addition, the paper presents a new type of model for linkage between financial accounting metrics including CAPEX(Capital Expenditure), OPEX(Operating Expenditure), EVA(Economic Added Value), DCL(Degree of Combined Leverage), and TPM productivity activities including AM(Autonomous Maintenance), PM(Preventive Maintenance), MP(Maintenance Prevention) and QM(Quality Maintenance). In order to support the evidence of proposed linkage strategy, a case analysis on 52 projects from national TPM contest from 2011 to 2012 is analyzed. The case presents the classification of CAPEX and OPEX activities from TPM, and proposes the correct implementation of financial effect for TPM projects.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.8
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• pp.797-806
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• 2008

In a double-passage cascade apparatus, only two blades are installed in order to increase the accuracy of experimental result by applying bigger blade than the size of multi-blades on the same apparatus. However, this causes difficulties to make correct periodic condition. In this study, sidewalls are designed to meet periodic condition without removing the operating fluid or adjusting tail boards. Surface Mach number on the blade surface is applied to a responsible variable, and 12 design variables which are related with sidewall profile control are selected. A gradient-based optimization is adopted for wall design and CFX-11 is used for the internal flow computation. The computed result shows that it could obtain the same flow structure by modifying only the sidewalls of the double-passage cascade apparatus.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.1034-1043
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• 1999

Rheological properties of dough made from waxy barley(Iri28) flour wheat flour mixtures with additives were investigated for the preparation of waxy barley bread using farinograph, extensograph and amy lograph. The water absorption, development time and dough weakness increased as the waxy barley flour level increased in all blends; however, dough stability decreased. Farinogram properties of 10% waxy barley flour added mixture were similar to those of 100% wheat flour. The addition of A.A(ascorbic acid), gluten, HPMC(hydroxy propyl methyl cellulose) improved rheological properties of dough with 30% waxy barley flour added mixture. In particular, stability and weakness of the dough showed greater dough improving effect by addition of A.A. For the extensograph data, strength, resistance and extensibility of dough decreased with increasing level of waxy barley flour. With the addition of additives, extensogram properties were variable for 30% waxy barley flour mixture. Of these additives, gluten had highest value in strength of dough. Addition of A.A and HPMC to 30% waxy barley flour added mixture resulted in an increase in the resistance and a decrease in the extensibility. Waxy barley flour added mixtures showed little higher gelatinization temperature on amylograph data than control. Maximum viscosity reduced as the waxy barley flour level increased. Also 30% waxy barley flour added mixture containing A.A and HPMC showed a decrease in maximum viscosity. But addition of gluten to 30% waxy barley flour mixture resulted an increase in the maximum viscosity. All of 30% waxy barley flour added mixture with additives had lower gelatinization temperature than those without additives. In the SEM images, starch granules were dispersed in a protein matrix. A non continuous, loose protein starch matrix was observed in all waxy barley flour mixture by SEM. Addition of additives gave the dough a more continuous structure with interactions between the starch granule and protein component.