• 동력기계공학회지
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• 제18권4호
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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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.

• 한국항만경제학회지
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• 제37권1호
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• pp.121-142
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• 2021

본 연구에서는 컨테이너 터미널의 변화요인(터미널 운영, 안전 및 법규, 조직문화, 기술발달, 사회외부적환경변화)이 컨테이너 터미널의 인력운영에 미치는 인과관계를 파악하고자 한다. 연구를 위해 부산, 광양항에 종사하는 터미널 관계자를 대상으로 300부의 설문지를 배포하였으며, 수집된 설문지 중 무응답 및 부실하게 응답한 설문지 53부와 결측치가 있는 16부의 설문지를 제거한 유효 설문지 231부를 통해 5가지 요인을 추출하였다. 이후 탐색적요인분석과 다중회귀분석을 진행하였으며 다음과 같은 결론을 도출할 수 있었다. 첫째, 컨테이너 터미널의 변화요인 중 기술발달(자동화), 조직문화, 사회·외부적환경 변화 요인이 컨테이너 터미널 인력운영에 유의미한 영향을 미친다는 사실을 도출해 낼 수 있었다. 둘째, 컨테이너 터미널 인력운영체계의 변화에 기술발달과 사회·외부적환경변화가 영향을 미치는 것으로 나타났다. 셋째, 인력구성(사무직/현장직)에 기술발달과 사회·외부적환경변화, 그리고 안전 및 보안이 영향을 미치는 것으로 나타났다. 넷째, 인력감소에 기술발달이 영향을 미치는 것으로 나타났다. 마지막으로 인력의 전문화 및 교육시스템에 기술발달과 사회·외부적환경변화, 그리고 터미널 운영이 영향을 미치는 것으로 나타났다.

• 전기학회논문지
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• 제59권8호
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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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• 제7권2호
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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.

• 지역사회간호학회지
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• 제12권3호
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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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• 제44권4호
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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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• 제17권6호
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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.

• 한국정보시스템학회지:정보시스템연구
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• 제26권3호
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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.

• 한국콘텐츠학회논문지
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• 제12권3호
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• pp.102-113
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• 2012

디지털 테크놀로지 시대에 새로운 가치를 추구하려는 노력은 사회 문화 전반 분야뿐만이 아닌 일반 교육계와 문화, 예술교육에도 변화를 요구하고 있다. 가장 큰 변화의 하나는 다른 영역간의 통합과 연계라는 추세가 문화와 예술분야에도 영향을 주면서, 문화와 예술이 통합을 이룬 문화예술 교육을 탄생하기에 이르렀다. 또한 새로운 시대는 디지털 테크놀로지의 활용이 교육 전 영역에서 활발히 사용되고 있으며, 문화 예술교육에도 테크놀로지의 활용이라는 새로운 시도를 요구하고 있다. 본 연구는 음악 테크놀로지를 활용한 문화예술교육에 대하여 이론적으로 알아보았다. 음악 테크놀로지의 활용은 다른 교과간의 통합적 접근으로의 가능성을 보여주며, 문화예술교육 외에 다양한 학문에도 적용이 가능함을 보여주었다. 음악 테크노로지의 활용은 현재 문화예술 교육 분야의 독특성, 전문성, 고유성을 반영해줄 만한 교수학습방법의 학습도구로서 다양한 대상과 상황에서 적용하여 실천적 사례를 쌓음으로서 문화예술 교육 분야를 위한 새로운 교수학습방법으로서의 역할을 할 수 있으리라 생각한다.