• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.4
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• pp.464-471
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• 2012

Self-excited induction generators (SEIG) are gaining importance as compared to conventional generators due to their capability toconvert wind energy into electrical energy for a wide range of variation in operating speed. The performance of such a generator depends upon the load, rotor speed and excitation capacitance. Therefore, depending upon the operating conditions, the output voltage and frequency of this machine goes on changing and this imposes a restriction on its usage. In order to maintain constant voltage and frequency, it need controllers, which make the circuit complicated and also increases the overall cost of power generation. This paper presents a simple controller to regulate the output voltage and frequency of SEIG for variation in its operating conditions due to any change in load, rotor speed and excitation capacitance (R, N, C) and their combination. The controller presented is simple in design, user friendly and is also less expensive, as the elements used in the controller are only resistors, inductors and capacitors. A block of SEIG for steady state operation is also modeled and presented in this paper. SEIG, Controller and other components are modeled and simulated using Matlab/Simulink.

• Journal of the Korean Solar Energy Society
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• v.39 no.5
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• pp.29-40
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• 2019

In response to the rapid climate change, in order to save energy in the field of buildings, the country is planning not only zero energy buildings but also zero energy cities. In the Urban Development Project, the Energy Use Plan Report is prepared and submitted by predicting the amount of energy demand at the planning stage. However, due to the activation of zero-energy buildings and the increase in the supply of new and renewable energy facilities, the energy consumption behavior of buildings in the city is changing from the previous ones. In this study, to estimate urban energy demand of Zero Energy City, building energy demand forecasts based on "Passive plans for use of energy based primary energy consumption", "Actual building energy usage data from Korea Appraisal Board" and "data from Certification of Building Energy Efficiency Rating" as well as demand forecast according to existing "Consultation about Energy Use Plan Code" were calculated and then applied to Multifunctional Administrative City 5-1 zone to compare urban total energy demand forecasts.

• Asia-Pacific Journal of Business
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• v.13 no.3
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• pp.35-57
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• 2022

Purpose - This study aims to conceptualize the construct of social media (SM) fatigue. Design/methodology/approach - A qualitative approach is employed to understand how SM users currently perceive (or interpret) the goals of SM usage and to conceptualize SM fatigue and its dimensions. We collected data through in-depth interviews of three SM users and group discussions among eighty SM users. Findings - we draw a definition of SM fatigue from a resource view that excessive SM use might lead to SM fatigue by depleting the internal resources of SM users. Further, through the analysis of the qualitative data from interviews and group discussions, we find the multi-dimensional nature of SM fatigue and identify five dimensions of SM fatigue-fatigue from the social obligation to interact with people, the importance of self-appearance, the quality of information, the quantity of information, and undesirable events-and common sources of fatigue in each dimension. Research implications or Originality - The conceptualization of SM fatigue elaborated in this study could enable scientific exploration of the role of SM fatigue in users' attitudes or behavior formation and change. On a practical front, this study would be valuable to companies by facilitating systematic investigations of their customers' fatigue through the lens of the SM fatigue dimensions.

• Journal of the Korean Society for information Management
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• v.38 no.3
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• pp.141-174
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• 2021

In this study, by examining the actual usage data of the university library website before and after COVID-19 outbreak, the usage behavior of users was analyzed, and the data before and after the virus outbreak was compared, so that university libraries can provide more efficient information services in a pandemic situation. We would like to suggest ways to improve it. In this study, the user traffic made on the website of University C was 'using Google Analytics', from January 2018 to December 2018 before the oneself of the COVID-19 virus and from January 2020 to 2020 after the outbreak of the virus. A comparative analysis was conducted until December. Web traffic variables were analyzed by classifying them into three characteristics: 'User information', 'Path', and 'Site behavior' based on metrics such as session, user, number of pageviews, number of pages per session time, and bounce rate. To summarize the study results, first, when compared with data from January 1 to January 20 before the oneself of COVID-19, users, new visitors, and sessions all increased compared to the previous year, and the number of sessions per user, number of pageviews, and number of pages per session, which showed an upward trend before the virus outbreak in 2020, increased significantly. Second, as social distancing was upgraded to the second stage, there was also a change in the use of university library websites. In 2020 and 2018, when the number os students was the lowest, the number of page views increased by 100,000 more in 2020 compared to 2018, and the number of pages per session also recorded10.46, which was about 2 more pages compared to 2018. The bounce rate also recorded 14.38 in 2018 and 2019, but decreased by 1 percentage point to 13.05 in 2020, which led to more active use of the website at a time when social distancing was raised.

• Journal of Society of Preventive Korean Medicine
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• v.22 no.2
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• pp.25-32
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• 2018

Objectives : This study was conducted to investigate the frequent diseases among the people who had been treated by collaborative treatment of Korean medicine and Western medicine, and to compare their medical use behaviors before and after the collaborative first-stage pilot project between Korean medicine and Western medicine. Methods : 4,467 patients were identified as the patients who are participated in the collaborative first-stage pilot project between Korean medicine and Western medicine during the period between July 15, 2016 and March 31 2017. We used 28,480 records of Korean national health insurance claim data from January 1 2016 to March 31 2017 to analyzed present condition of cooperative medical usage. Also we conducted a paired t test to compare the percentage of collaborative treatment days before and after the pilot project period. Results : We found that the most frequent diseases treated in the pilot project were the diseases of musculoskeletal and nervous system and then 10 major diseases such as H, K, J, C (D), N, L, E, A, H and F disease codes in order. Also it was confirmed that 14 major and 53 medium diseases are included from more than 90% of total patients. As a result of high frequency of medical treatment in Western medicine or Korean medicine is "administration of Korean medicine", which is same as before and within the pilot project. The ratio of utilizing both Western and Korean medical care for the same disease on the same day by both general patients and patients in KCD-7 disease code group C, G, I, M and S had been increased significantly. Conclusions : The pilot project might change the behavior of utilizing the medical care service by increasing the ratio of collaborative treatment of Western medicine and Korean medicine for the same disease on the same day.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.59-66
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• 2017

In this paper, to protect the piping in nuclear power plants and various plant facilities, we have developed a damper using the friction method and carried out a study to analyze the performance. Friction typed damper means a device for attenuating vibration by generating a frictional force to the bearing and the shaft by applying a compressive force to the MER-Spring. In order to analyze the performance of the damper, the properties of MER-Spring and friction materials were analyzed, a study on the effects of friction was carried out, and the behavior of this equation was established. And, to determine whether deformation of the material and to examine the reliability of the behavior equation established, prototypes was produced and, through a performance test and finite element analysis of a damper made of specimens, they were analyzed. As a result, it is noted that the reliability of the material was confirmed, the coefficient of friction have to be adjusted according to the velocity, cyclic loading test and finite element analysis results show exhibits excellent results. In addition, a review of the dynamic loads in the future shall be performed for the usage in more broad fields.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.116-128
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• 2022

Purpose: The paper aims to: 1) identify the reasons for the low usage of recycled paper in domestic workplaces and the premature state of recycled paper industry; 2) assess the environmental effects of replacing domestically consumed copy papers with recycled papers; and 3) suggest ways in which the recycled paper industry can expand in South Korea. Method: Questionnaire survey with cluster sampling is used to identify the attitudes and behavior with respect to recycled copy paper, the results of which are analyzed using SPSS. The environmental effect of replacing copy papers with recycled paper is assessed through the Life Cycle Assessment approach and Paper Calculator V4.0. Result: While the respondent's experience in using recycled copy paper was relatively low, they tend to acknowledge the need for its use and show relatively high satisfaction with the quality of the recycled paper. The environmental benefits of replacing ordinary copy paper with 40%+ recycled paper under the 10% market share increase scenario amounts to 60,000 tons of CO₂ emissions reductions. Conclusion: The results from the attitude survey and market research, five approaches to improving the recycled copy paper market are suggested.

• Journal of Distribution Science
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• v.11 no.10
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• pp.47-53
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• 2013

Purpose - Six months have passed since the amendment of the SSM regulation law; however, as yet, there is no confirmed research or report on the effects of this amendment, which are indefinite. Further, there have been no attempts to study the effects of the SSM regulation law from the consumers' viewpoint, which is important because consumers are the main agents that are greatly influenced by the amendment law. Therefore, this study aims to investigate the consumers' attitude toward the SSM regulation law as well as the effects of the SSM regulation law on the changes in purchase behavior. Research design, data, and methodology - This study was initiated from four research problems that are linked to consumer reaction to the SSM regulation law. Research problem 1: What is the consumers' reaction (perception, attitude, and perceived fairness) to the SSM regulation law? Research problem 2: How do the consumers' reactions to the SSM regulation law differ by consumers' characteristics? Research problem 3: Could the SSM regulation law change a consumer's purchase behavior? Research problem 4: Is it necessary to amend the SSM regulation law? This study collected the data through the interview and survey of housewives for the purpose of solving the research problems. The interview was conducted as a pilot study for the field survey. We interviewed three housewives, who were: an employed housewife, a full-time homemaker, and a manager of a housewife club, respectively. We then conducted a field survey of 232 housewives who were housewife club members or elementary school parents in Chunghcheong-do. Results - We verified the reliability and validity of the data, and analyzed it to solve the research problems. The main findings of this study were as follows. First, consumers still have a positive attitude toward large discount chains and SSM, which has been the case since the law was introduced. Second, perceived risk of consumers associated with traditional markets and small neighborhood shops was low. Third, consumers think that amendments of the SSM regulation law are important, and they positively assess the satisfaction, necessity, and propriety of the law. Fourth, although the SSM regulation law caused inconvenience to consumers, this law did not have any influence on the usage frequency and the use-behavior of large discount chains. Finally, consumers reacted very negatively to the toughening up of the SSM regulation law. Conclusions - In short, consumers still have a positive attitude toward the SSM regulation law. However, this act did not have any influence on the use-behavior of large discount chains (General Super Market). Thus, policy making authorities require active communication and promotions to enhance the effect of the SSM regulation law. This study was of the nature of exploratory research, which did not focus on hypothesis testing, but on finding solutions to the research problems. Therefore, this study is no more than a simple data analysis. Future studies should attempt to investigate the actual effects of the SSM regulation law, on the basis of sufficient literature review and real sales data.

• Journal of Korean Society of Transportation
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• v.35 no.1
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• pp.50-62
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• 2017

As the use of private cars increases along with the technological advancement in the automobile industries and their capabilities to supply, a wide range of issues are followed including the increase in traffic congestion costs, pavement damages and more. In spite of consistent effort to resolve such urban traffic problems, the modal share rate of private cars continuously increases, thus it is becoming more important to explore the ways to enable drivers to take reasonable measures, in self-motivated manner, by taking part of the transportation demand management policy rather than to rely on the strict enforcement of control policy. Considering that the urban transportation infrastructures are in much better shape than before, it is necessary to implement Mobility Management (MM) that induces reasonable usage of private cars by promoting the change in one's consciousness and behavior through communication. Hence, the research studies the factors that influence the mobility through the survey targeting the citizens of Busan on their awareness on the former transportation demand management policy, to explore the ways to motivate the citizens' involvement in reducing the use of private cars as a measure of Mobility Management.

• Korean Journal of Environmental Biology
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• v.26 no.2
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• pp.121-127
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• 2008

As a step toward developing conservation and restoration plans for an endangered species of the Oriental White Stork (Ciconia boyciana), we studied daily foraging behavior and ecology. We released two individuals, male and female, after enclosing study site with a fence and cutting out a part of two or three feathers of primaries. Research was conducted from 16 June to 11 July, 2007 for 25 days at Whawonri, Mewonmyung, Chungbuk province. We investigated diural and daily variation of foraging time budget, diet composition, and habitat selection of the feeding individuals. The storks quadratically invested for foraging time and resting time according to time of day, but no significant variation in the foraging time and resting time appeared daily over 25 days. As a result, the storks mainly used wetland as a foraging site in the center of the study area to that in the edge as well as to other types of habitat. The high usage for wetland in the center did not change over the 25 days while Rice field decreased and Wetland in the edge and Pathway increased. Female invested more time for foraging than male, but the foraging efficiency did not differ between them. We discussed the significance of foraging behavior and habitat selection for management plan.