• Proceedings of the KIPE Conference
• /
• 2000.07a
• /
• pp.163-167
• /
• 2000

This paper presents the digital control of single-phase power factor correction(PFC) converter which has the variable gain according to the condition of inner control loop error. Generally the gain of inner current control loop in single-stage PFC converter has a constant magnitude. This has a bad influence on the power factor because current loop doesn't operate smoothly in the condition that input voltage is low In particular a digital controller has more time delay than an analog controller and degrades This drops the phase margin of the total digital PFC system,. It causes the problem that the gain of current control loop isn't increased enough. In addition the oscillation happens in the peak value of the input voltage open loop PFC system gain changes according to ac input voltage. These aspects make the design of the digital PFC controller difficult The digital PFC controller presented in this paper has a variable gain of current control loop according to input voltage. The 1kW converter was used to verify the efficiency of the digital PFC controller.

• Industrial Engineering and Management Systems
• /
• v.15 no.1
• /
• pp.99-109
• /
• 2016

During the last two decades, impact factor has been widely used as a journal evaluation metric that differentiates the influence of a specific journal compared with other journals. However, impact factor does not provide a reliable metric between journals in different subject categories. For example, higher impact factors are given to biology and general sciences than those assigned to other traditional engineering and social sciences. This study initially analyzes the trend of the time series of the impact factors of the journals listed in Journal Citation Reports during the last decade. This study then proposes new journal evaluation metrics that adjust the impact factors across different subject categories. The proposed metrics possibly provides a consistent measure to mitigate the differences in impact factors among subject categories. On the basis of experimental results, we recommend the most reliable and appropriate metric to evaluate journals that are less dependent on the characteristics of subject categories.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.5
• /
• pp.111-120
• /
• 2021

A tractor is an agricultural machine that performs farm work, such as cultivation, soil preparation, loading, bailing, and transporting, through attached working implements. Farm work must be carried out on time per the growing season of crops. As a result, the reliability of a tractor's transmission is vital. Ideally, the transmission's design should reflect the actual load during agricultural work; however, configuring such a measurement system is time- and cost-intensive. The design and analysis of a transmission are, therefore, mainly performed by empirical methods. In this study, a tractor with a measurement system was used to measure the actual working load in the field. Its hydro-mechanical transmission was then analyzed using the measured load. It was found that the velocity factor, load distribution factor, lubrication factor, roughness factor, relative notch sensitivity factor, and life factor affect the gear strength of the transmission. Also, loading conditions have a significant influence on the reliability of the transmission. It is believed that transmission reliability can be enhanced by analyzing the actual load on the transmission, as performed in this study.

• The Journal of Information Systems
• /
• v.23 no.1
• /
• pp.73-91
• /
• 2014

Microblog is emerging as a new communication service because of its usefulness and real-time accessability. Recently, microblog services, such as twitter and me2day in Korea, are getting a great attention. Continuous use intention is critical to sustain the service. However, most recent studies are based on Technology Acceptance Model(TAM) and Expectation Confirmation Model(ECM). These models are only focused on individual factors and overlook social influence factors. Social influence has been indicated as a critical factor of technology adoption and diffusion in social context(Davis, 1989; Fulk et al., 1987). In this study, we explore factors related to social influence which effect on continuous use intention for 'me2day' that is one of the most famous microblog in Korea. The purpose of this study is to understand continuous use intention and examine the relationship among social influence factors, social presence, and continuous use intention. To understand the phenomenon of continuous use intention in microblog service, this study employed social influence theory and expanded it by adding personal network exposure and group norm as additional social influence factors. The results show that social identity, group norms, and social presence positively influences continuous use intention. Contrary to our expectation, personal network exposure does not influence on continuous use intention. Academically, this research can contribute to microblog research field through elucidating the relationship among social influence factors, social presence, and continuous use intention. Although there is not enough research which is considered social influence factors as major explanation for continuous use intention, this study can give novel point of view to understand continuous use intention of microblog. Practically, service providers could consider ways to encourage users to continually use microblog service by reinforcing social influence factors and social presence.

• Journal of The Korean Association of Information Education
• /
• v.19 no.3
• /
• pp.287-298
• /
• 2015

Digital textbook is noted as a new education materials to realize a new education paradigm with changes in digitalized society. The purposes of this study is investigation of key factors on digital textbook satisfaction by selecting of the three factors(domestic environment factor, teachers factor, school environment factor), analysis of awareness of effect factors on digital textbook satisfaction, and verification for each effect factors' influence on elementary school. 201 elementary school students, 201 their parents, and 12 teachers in Chung-nam were surveyed and factors which influenced on digital textbook satisfaction were analyzed. According to the results, firstly, there was a statistical significant difference in domestic internet environment, device owned environments, the utilization of the internet for the purpose of education and using time, device type of teachers, lesson time of digital textbook used in class and time ratio. Secondly, multiple regression analysis was conducted to find out the influence on digital textbook, the Awareness of parents about digital textbook, The lesson time using digital textbook by teacher, The utilization of the internet for the purpose of education affected satisfactions significantly in the order. This study has significant implications about which we have provided the effort needed to use digital textbook.

• Korean Journal of Construction Engineering and Management
• /
• v.20 no.1
• /
• pp.133-140
• /
• 2019

The concrete mix should be designed and produced to reflect the specific site conditions during concrete placement. That is, the concrete mix design should be planned considering temperatures, work environments, pouring methods, etc. The objective of this research is to understand the external factors of curing temperature and delay time that influence concrete strengths during pouring work, and provide concrete mix design that can be most robust to the effects of external factors. The Taguchi's robust method is used in preparing the concrete mix design to achieve the research objective. In a case study, an indoor concrete test was performed to find the optimal combination of concrete mixes with external factors of curing temperature and delay time. Concrete test cylinders were made to test concrete strengths given different external factors. The study results showed that the optimal performance of concrete strength can be achieved by applying the robust method when preparing a concrete mix design.

• 한국노년학
• /
• v.36 no.4
• /
• pp.1191-1206
• /
• 2016

The purpose of this study is to investigate the relationship between perceived health status, future time perspective(FTP), health promoting behaviors, and quality of life in the elderly. To this end, the survey was conducted through distributing questionnaires to the elderly people who lived in areas of Seoul or its adjacent satellite cities in their age of 60 or more in 2013. In total, 497 valid responses were collected. The data was analyzed by using a number of analysis methods including confirmatory factor analysis, reliability analysis, frequency analysis, correlation analysis, simple regression analysis, multiple regression analysis, SEM analysis. The findings are as follows. First, health status of the elderly has a significant influence on FTP. Second, health status the elderly has a significant influence on health promoting behavior. Among sub-factors of health status, subjective health status has a significant influence on spiritual growth, nutrition, physical activity, stress and interpersonal relation. Third, health status of the elderly has a significant influence on quality of life. Among sub-factors of health status, subjective health status has a significant influence on physical, social, emotional and economic quality of life. Fifth, FTP of the elderly has a significant influence on quality of life. FTP has a significant influence on physical, social, emotional economic quality of life among the elderly. Sixth, health promoting behavior among the elderly has a significant influence on quality of life. Among sub-factors of health promoting behavior, spiritual growth has a significant influence on physical, social, emotional and economic quality of life. Nutrition has a significant influence on social factor. Health responsibility has a significant influence on emotional quality of life. Physical activity has a significant influence on physical quality of life. Stress has a significant influence on physical, social and economic quality of life. Finally, interpersonal relation has a significant influence on physical and social quality of life.

• Physical Therapy Korea
• /
• v.14 no.3
• /
• pp.23-31
• /
• 2007

The purpose of this study was to determine the influence of high-heeled shoes on walking of obese women as it was already proven an extrinsic factor of knee osteoarthritis in women with normal weight. In this study the aimed therefore in particular was to utilize high-heeled shoes in proving it's causal influence on knee osteoarthritis by measuring the angle and torque of the knee joint. Fifteen obese women (BMI>25 $kg/m^2$) were measured in their twenties. Each angle and torque of their knee joints during walking on 6.5 cm high-heeled shoes and with a bare feet, were compared with each other and analyzed with a 3D motion analysis system. There was no significant difference in walking speed, cadence and stride length between the two conditions. However, there was a significant increase in a double limb support time and the stance phase when walking on high-heeled shoes as when walking with bare feet. The peak knee flexion angle and peak knee varus torque was higher when walking on high-heeled shoes than with bare feet. On the contrary, the peak knee flexion angle in the swing phase was not statistically different. The prolongation of peak knee varus torque was also proven. There was a significant increase in peak knee varus torque in the initial and last stance phases during walking on high-heeled shoes as compared to walking on bare feet. Through the above results, it was proven that when obese women walked on high-heeled shoes, rather than with bare feet, peak knee flexor and varus torque increased along with the changes of the in knee joint angle. Therefore, the influence of high-heeled shoes might be a significant intrinsic factor in knee osteoarthritis of obese women.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.8
• /
• pp.3726-3734
• /
• 2012

This study evaluated the behavior of pollutants based on the seasonal change by selecting the branch river's factors that influence the outflow of pollutants in Soyang lake basin. The analysis method was the factor analysis that classified the factors of the drainage area influencing the outflow of pollutants, and evaluated selected representative factors. As a result of the study, SS and T-P factors should be classified as similar factors to the storm water runoff, and the improvement of water must be strived through managing source of pollution at the time of no rain. Second, as the result of the influence from the factors, spring and winter seasons usually exert 36% influence and summer and fall exert over 90% significant influence that the improvement of water through managing source of water seems possible. At last, the prediction about delivery pollution load considering the outflow characteristic of pollutants at the drainage area based on seasonal change by regarding selected factors as independent variables is possible.

• Journal of Korean Academy of Nursing
• /
• v.14 no.2
• /
• pp.84-92
• /
• 1984

This article examined relationships between selected variables, such as demographic background, care, treatment variables, environmental characteristics, and patient's daily behavior and mood change. Relationship were determined between independent variabltherapeutic-rapeutie approach, demographic data, environmental management approach-,and dependent variable-patient's daily behavioral and mood change. 35 patients selected within some criteria in a psychiatric ward, were obserbed during 5 weeks by use of Wyatt's Behavior & Mood Rating Scale ac-cording to the object of the study. At the same time, the frequence of the care and treatment were collected. Criteria for sample selection and independent variables as an influential factor to the patient behavioral change, based on a literature revienw and clinical experiences. Pearson's correlation and multiple regression analysis were used to determine the influfntial factors to the patient behavioral change. Systematic reading (r=.8324), Psychiatrist's individual interview (r=.5764), tranquilizer (r=.3441) and hospitalization processing date (r=.4143) were related with patient's behavioral change. That is these 4 variables can be said to influence to the patient's behavior and mood. A stepwise multiple regression analysis of the effect of the independent varibles of systematic reading, psychintrists individual interview, tranquilizer and hospitalization processing date on the dependent variable, patient's behavioral change was carried out. Systematic reading with on R²of. 69 revealed to be the main influential factor to the patient's behavior and mood change, as the next factor psychiatrist individual interview. A total inclusion of these factors revealed a 73% prediction for the patient's behavior and mood change. But the most influential factor was the interaction of the systematic reading and psychiatrist's individual interview.