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Shin K.J.,Suncheon First College | Cha H.R.,Korea Institute of Industrial Technology | Seo Y.J.,SRC Inc. | Lim J.Y.,Seojin Technology Ltd. Co.
ICEMS 2012 - Proceedings: 15th International Conference on Electrical Machines and Systems | Year: 2012

In this paper, the design of the 3 phase inverter using the adaptive control of DC-link Current was carried for electrical bike. The SVPWM-VSI(Space Vector Pulse Width Modulation of Voltage Source Inverter) is analyzed for the induction motor of outer rotor type and a variable DC link current inverter system is applied to improve the performance of torque and speed in the overall operation range of an induction motor drive. This inverter system controls the magnitude of a DC link current actively according to the speed and load conditions of an induction motor, therefore in spite of a low speed range, the width of effective voltage vector in a gate signal is increased and the output voltage error of the inverter is decreased when compared with a fixed DC link current inverter system. The proposed algorithm is verified through experimental results. © 2012 IEEJ Industry Appl Soc. Source


Cha H.R.,Korea Institute of Industrial Technology | Shin K.J.,Suncheon First College | Seo Y.J.,SRC Inc.
2011 International Conference on Electrical Machines and Systems, ICEMS 2011 | Year: 2011

In this paper, the optimization design of outer rotor IPM type PMSM was carried out for electric vehicle traction having 3 wheel system. The half round shape was proposed to reduce the cogging torque due to IPM machine characteristics. The object of optimization design is to find out most effective factor in reducing the torque ripple which may occurs the noise, vibration and uncomfortable riding of EV. In order to satisfy the low cogging torque, some design parameter such as air-gap, number of slot, poles, and slot open size was evaluated. From the simulation results of the outer rotor type IPM, we find out that the combination of slot open and depth of magnet is most important factor for reducing the cogging torque and high performance in low speed operational area. Moreover, the prototype of designed outer rotor IPM type PMSM was carried out and verified their properties. © 2011 IEEE. Source


Kim H.-H.,Yonsei University | Lee C.-S.,Yonsei University | Jeon J.-M.,Suncheon First College | Yu S.-D.,National Health Research Institute | And 4 more authors.
Environmental Science and Pollution Research | Year: 2013

The objectives of this study were to survey elementary school students regarding the environmental conditions of their elementary schools and to assess the relationship between air pollution and allergic disease using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Therefore, this study was designed as a cross-sectional study. In this study, seven elementary schools were selected and they were classified into three categories. The selection included one school with no traffic-related or other pollutants, three with traffic-related pollutants, and three with traffic-related and other pollutants from industrial and filling station sources. The ISAAC questionnaire survey was given to all of the students except to those in the 1st grade who were presumed to be less likely to be exposed to the school environment than the remainder of the students attending those seven schools. The assessment of allergic disease was conducted on a total of 4,545 students. Three school zones with critical exposure were selected within each school and they were evaluated based on the levels of black carbon (BC), PM10, SO2, NO2, and O3. There was a significant increase in the risks based on the odds ratios of treatment experiences (within 1 year) for allergy-related diseases such as asthma and allergic rhinitis (a) in the school group with traffic-related pollutants and the school group with complex pollutants were 2.12 (1.41-3.19) and 1.59 (1.06-2.37), respectively, in comparison to the school groups with no exposure to pollutants. This was determined based on the odds ratio of symptoms and treatment experiences for allergy-related diseases by group based on the home town zone as a reference. Also, in the case of atopic dermatitis, the odds ratio of treatment experiences (within 1 year) was 1.42 (1.02-1.97), which indicated elevated risks compared to the students in the S1 school. A regression analysis was used to assess the relationship between the substances and the symptomatic experiences within the last year. There were significant increases in the odds ratio of the symptoms associated with allergic rhinitis and the BC and SO2 in the complex pollution areas. The results of the assessment of the relationship between atopic dermatitis-associated symptoms and O3 showed that the odds ratio increased with statistical significance. © 2013 Springer-Verlag Berlin Heidelberg. Source


Park S.A.,Suncheon First College | Sung K.M.,Gyeongsang National University
Journal of Korean Academy of Nursing | Year: 2014

Purpose: This study was done to develop a measurement for stress experienced by patients with schizophrenia during hospitalization. Methods: The preliminary tool was developed through in-depth interviews and a validity verification test of content. For data collection, 15 inpatients with schizophrenia were selected as participants for in-depth interviews and 195 patients admitted to one of eight psychiatric hospitals in four provinces were recruited as participants to test reliability and validity of the preliminary tool. Results: The questionnaire was developed as a four-point Likert-type scale in a self-report form with 28 items. Factor analysis showed 28 items in six factors. Factors were named 'Unjust human rights infringement', 'Futureless life', 'Alienation from other family members', 'Infringement of basic needs', 'Infringement of personal preference' and 'Inconvenience of shared living'. The six factors explained 63.5% of the total variance. Cronbach's alpha for the total items was.93 and for the factors ranged from. 65 to 87. Conclusion: A tool to measure stress in patients hospitalized with schizophrenic was developed based on identified hospitalization stress experiences. Study results indicate that this tool can be used to evaluate hospitalization stress in these patients and will contribute to establishing nursing interventions for relief of hospitalization stress. © 2014 Korean Society of Nursing Science. Source


Kim H.-H.,Yonsei University | Lim Y.-W.,Yonsei University | Jeon J.-M.,Suncheon First College | Kim T.-H.,Yonsei University | And 5 more authors.
Asian Journal of Atmospheric Environment | Year: 2013

In the study, pollution levels of indoor polycyclic aromatic hydrocarbons (PAHs) in public facilities (vapor phase or particulate phase) were evaluated, and a health risk assessment (HRA) was carried out based on exposure scenarios. Public facilities in Korea covered by the law, including underground subway stations, funeral halls, child care facilities, internet cafes (PC-rooms), and exhibition facilities (6 locations for each type of facility, for a total of 48 locations), were investigated for indoor assessment. For the HRA, individual excess cancer risk (ECR) was estimated by applying main toxic equivalency factor (TEF) values suggested in previous studies. Among the eight public facilities, internet cafes showed the highest average PM2.5 concentration at 110.0 μg/m3 (range: 83.5-138.5 μg/m3). When assuming a risk of facility exposure time based upon the results of the surveys for each public facility, the excess cancer risk using the benzo(a)pyrene indicator assessment method was estimated to be 10-7-10-6 levels for each facility. Based on the risk associated with various TEF values, the excess cancer risk based upon the seven types cancer EPA (1993) and Malcolm & Dobson's (1994) assessment method was estimated to be 10-7-10-5 for each facility. The excess cancer risk estimated from the TEF EPA (2010) assessment was the highest: 10-7-10-4 for each facility. This is due to the 10-fold difference between the TEF of dibenzo(a,e)fluoranthene in 2010 and in 1994. The internet cafes where smoking was the clear pollutant showed the highest risk level of 10-4, which exceeded the World Health Organization's recommended risk of 1×10-6. All facilities, with the exception of internet cafes, showed a 10-6 risk level. However, when the TEFs values of the US EPA (2010) were applied, the risk of most facilities in this study exceeded 1×10-6. Source

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