• Journal of Power System Engineering
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• v.18 no.4
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• pp.29-35
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• 2014

Plate heat exchanger are being applied in the field of OTEC (ocean thermal energy conversion) and SWAC (seawater air conditioning) system. This study is to analyze numerically the heat transfer and pressure drop characteristics by using solid works flow simulation in order to offer optimum design data of plate heat exchanger. Plater heat exchanger proposed in this study is four types. The geometric design parameters of plate heat exchanger are a channel space, a flow orientation, a plate array, the flowrate of working fluid and so on. The main results for numerical analysis of plate heat exchangers are summarized as follows. Heat transfer performance for the channel space of 2.4 mm shows the highest value compared to other spaces. And, the Type 4 plate heat exchanger in Table 2 is the highest performance. From the pressure drop characteristics of plate heat exchanger, the channel space of 3.2 mm shows the lowest value. And Type 1 plate heat exchanger in Table 2 is the lowest pressure drop.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.37-37
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• 2010

In these days $SF_6$ mixtures and alternative gas has been studied because of global warming. so although many studies have been carried out about binary gas mixtures with $SF_6$, few studies were presented about breakdown characteristics of $SF_6/N_2$ mixtures. In this paper, breakdown experiment values and breakdown simulation value are compared. Streamer theory was used for predicting breakdown voltage. For accurate simulation, this simulation apply utilization factor using CST program. AC breakdown experiments in non-uniform field was performed to compare with the breakdown simulation values. But with gap lengths increasing, the breakdown voltage is saturated. So simulation need surface roughness factor.

• Journal of Korea Port Economic Association
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• v.37 no.1
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• pp.121-142
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• 2021

The purpose of this study is to identify environmental factors affecting manpower utilization of container terminals. 300 questionnaires were distributed to employees working in terminal operators in Busan and Gwangyang port. Based on the results of multiple regression analysis, first, it is proved that technology development, organizational culture and social·external environment have a significant impact on manpower utilization of container terminals. Second, this study found that technology development and social·external environment have a significant impact on manpower utilization of container terminals system. Third, it is found that technology development, social·external environment, safety and security change the composition of the workforce between office and field employees. Forth, the number of workforce is expected to gradually decrease due to technology development. Finally, it is found that technology development, organizational culture, social·external environment and terminal operation have a impact on specialization and training system of human resoures.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.8
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• pp.1416-1422
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• 2010

$SF_6$ is the most commonly used insulating gas in electrical systems. But In these days $SF_6$ mixtures and alternative gas has been studied because of global warming. so although many studies have been carried out about binary gas mixtures with $SF_6$, few studies were presented about breakdown characteristics of $SF_6/N_2$ mixtures. At present study the breakdown characteristics of $SF_6/N_2$ mixtures in Non-uniform field was performed. In this paper, The simulation value are compared with experiment values. Streamer breakdown criterion was used for predicting breakdown voltage. For accurate simulation this simulation apply utilization factor using CST(computer simulation technology) EM $studio^{tm}$ program. AC breakdown experiments in non-uniform field was performed to compare with the breakdown simulation values. The pressure range of gas mixtures was 0.4 MPa to 0.7 MPa. The rod-plane was used and mixture ratio is $SF_6$ 20% : $N_2$ 80%. The gap lengths are 10mm to 70mm. As the pressure increase, this simulation value does not correspond to the experiment value. So this simulation need surface roughness factor. As a result of applying surface roughness factor this simulation decrease a relative error (|experiment value - simulation value| /simulation value).

• Journal of information and communication convergence engineering
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• v.7 no.2
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• pp.209-214
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• 2009

The employment of the induction generator is preferable in the natural energy utilization by the minimum maintenance and the mechanical robustness, Another merit is also expected when it is connected to the power network system, because constant-voltage and constant frequency (CVCF) power generation is easily realized in spite of the variation of the rotor speed. However the induction generator needs much amount of the reactive power that reduces power factor in the primary side. The improvement of power factor in the primary side requires large VAR compensator, this point is solved, the merit of the induction machine as a main generator will become more established. This paper proposes a novel approach where the secondary is controlled by a PWM inverter not only to get CVCF power but also to improve the primary power factor. Basically the inverter is controlled so that the field current is supplied from the secondary side in this approach. The required capacity of the inverter is small, because only the slip power is controlled in the secondary side. In the experimental system where the sea wave torque simulator is used, the power factor is well improved by the microcomputer controlled PWM inverter.

• Research in Community and Public Health Nursing
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• v.12 no.3
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• pp.582-588
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• 2001

Purpose : This study is to examine the characteristics of the elderly and their family caregivers. to study the main factors affecting Nursing Home utilization, and to help frame a policy about Nursing Home's demand. management and welfare facilities. Method: Data for this present study were collected via questionnaires randomly distributed to family caregivers of the over 60-year-old patients at general hospital and university hospital in Seoul. Kyung-Ki Do and In-Chon from 26 June to 20 July, 2000. Questionnaires were issued to 512 people and 479 were returned. The data was analyzed by frequency, $x^2$-test, t-test, ANOVA. factor analysis. correlation coefficients analysis and Stepwise multiple regression analysis using SPSS 9.0. Result First. Instrumental Activities of Daily Living(IADL), duration of hospitalization, sex, marital status, behavior problems, home ownership, and cognitive disorder about elderly patients affect family caregivers burden. one of need factors. Secondly, marital status. religion. health status, sex, education and age in the family caregiver predisposing factors are main factors on Nursing Home utilization. Third, in need factors, care burden. time burden, family relation burden, physical burden and mental burden have an effect on Nursing Home utilization. Finally, the model the most important factors that affect Nursing Home utilization is composed of six of eleven totally, care burden, religion, time burden, health status, marital status and education. When the family caregivers get care burden and time burden. are highly educated, have no religion, have health problems, and have no spouse, it is possibility for them to utilize Nursing Homes. Conclusion: The government should decrease a family caregivers burden and seek to find how to support Nursing Homes. Furthermore. Social support program for the family caregivers should be required. Thus, the family caregivers need consultation and need to meet to talk about their patients. how to care them, get information, which are the crucial field in advancing the research in nursing science.

• Journal of Ginseng Research
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• v.44 no.4
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• pp.627-636
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• 2020

Background: Cultivation of medicinal crops, which synthesize hundreds of substances for curative functions, was focused on the synthesis of secondary metabolites rather than biomass accumulation. Nutrition is an important restrict factor for plant growth and secondary metabolites, but little attention has been given to the plasticity of nutrient uptake and secondary metabolites synthesis response to soil nitrogen (N) change. Methods: Two year-field experiments of Sanqi (Panax notoginseng), which can synthesize a high level of saponin in cells, were conducted to study the effects of N application on the temporal dynamics of biomass, nutrient absorption, root architecture and the relationships between these parameters and saponin synthesis. Results: Increasing N fertilizer rates could improve the dry matter yields and nutrient absorption ability through increasing the maximum daily growth (or nutrient uptake) rate. Under suitable N level (225 kg/ha N), Sanqi restricted the root length and surface and enhanced the root diameter and N uptake rate per root length (NURI) to promote nutrient absorption, but the opposite status of Sanqi root architecture and NURI was found when soil N was deficient. Furthermore, increasing N rates could promote the accumulation of saponin in roots through improving the NURI, which showed a significant positive relationship with the content of saponin in the taproots. Conclusion: Appropriate N fertilizer rates could optimize both root architecture and nutrient uptake efficiency, then promote both the accumulation of dry matter and the synthesis of saponins.

• Journal of Information Processing Systems
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• v.17 no.6
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• pp.1097-1114
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• 2021

The primary objective of this work was to discover a solution for the survival of people in an emergency flood. The geographical information was obtained from remote sensing techniques. Through helpline numbers, people who are in need request support. Although, it cannot be ensured that all the people will acquire the facility. A proper link is required to communicate with people who are at risk in affected areas. Mobile sensor networks with field-programmable gate array (FPGA) self-configurable radios were deployed in damaged areas for communication. Ad-hoc networks do not have a centralized structure. All the mobile nodes deploy a temporary structure and they act as a base station. The mobile nodes are involved in searching the spectrum for channel utilization for better communication. FPGA-based techniques ensure seamless communication for the survivors. Timely help will increase the survival rate. The received signal strength is a vital factor for communication. Cognitive radio ensures channel utilization in an effective manner which results in better signal strength reception. Frequency band selection was carried out with the help of the GRA-MADM method. In this study, an analysis of signal strength for different mobile sensor nodes was performed. FPGA-based implementation showed enhanced outcomes compared to software-based algorithms.

• The Journal of Information Systems
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• v.26 no.3
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• pp.1-23
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• 2017

Purpose With the advent of the 4th Industrial Revolution era, ICT convergence industry is leading the wave of new change. These changes in the industrial field are recognizing convergence as a strategic cooperation tool of management for creating new value. In order to achieve the research purpose, conceptual understanding of ICT convergence is summarized by focusing on concepts, features, types and cases. In addition, this study established the theoretical rationale for the determinants of ICT convergence performance, and examined previous researches related to ICT convergence. Design/methodology/approach The empirical research method is based on a survey of 510 companies including managers and mid-level practitioners who understand the contents of the relevant field, 305 data were used for analysis. We conducted exploratory factor analysis to verify the grouping of these questionnaire items and conducted confirmatory factor analysis to analyze the validity and reliability of the measurement model. Through the statistical analysis, we analyzed the structural relationship of ICT firms' competencies for convergence performance. Findings Linkage of ICT strategies established by corporations is an important factor for enhancing resource capacity and convergence ability. It is important to ensure that product innovation, consumer-oriented strategies, and ICT strategies for the implementation of business strategies are closely linked. In addition, in the convergence environment, companies should make efforts to develop convergence ability and improve organizational performance through utilization of ICT resources. From the CEO's perspective, it is necessary to understand the knowledge, technology and resources arising from the convergence environment, and to integrate with the resources possessed by the enterprise to induce the organization's performance.

• The Journal of the Korea Contents Association
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• v.12 no.3
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• pp.102-113
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• 2012

The effort to generate new values in this age of digital technology characterized by rapid changes in information and knowledge demands transformations not only in the sociocultural and educational spheres but also specifically in the field of arts and culture education. One of the greatest transformations is emphasis on integration and consilience among different fields which has impacted the field of arts and culture, giving birth to the practice of arts and culture education. Digital technology actively utilizes in lots of subjects, which, also becomes a challenging factor for the field of arts and culture education. In this context, this study theoretically considered to approach music technology to use for the field of arts and culture education. Utilization of music technology takes interdisciplinary approaches combining various subjects in the field of arts and culture education. Considering the current circumstances in which there is a lack of teaching and learning methodologies which reflect the unique, specialized nature and the intrinsic originality of the field of arts and culture education. It is deemed that by accumulating more case studies applying music technology in practice to a wider variety of targets and situations. Music technology will serve the role of an important a learning tool for the arts and culture education field.