• Journal of The Korean Astronomical Society
• /
• v.49 no.5
• /
• pp.209-223
• /
• 2016

We present analyses of ~1250 variable sources identified in a 20 square degree field toward NGC 2784 by the KMTNet Supernova Program. We categorize the variable sources into three groups based on their B-band variability. The first group consists of 31 high variability sources with their B-band RMS variability greater than 0.3 magnitudes. The second group of medium variability contains 265 sources with RMS variability between 0.05 and 0.3 magnitudes. The remaining 951 sources belong to the third group of low variability with an RMS variability smaller than 0.05 magnitudes. Of the entire ~1250 sources, 4 clearly show periods of variability greater than 100 days, while the rest have periods shorter than ~51 days or no reliable periods. The majority of the sources show either rather irregular variability or short periods faster than 2 days. Most of the sources with reliable period determination between 2 and 51 days belong to the low-variability group, although a few belong to the medium-variability group. All the variable sources with periods longer than 35 days appear to be very red with B - V > 1.5 and V - I > 2.1 magnitudes. We classify candidates of 51 Cepheids, 17 semi-regular variables, 3 Mira types, 2 RV(B) Tauri stars, 26 eclipsing binary systems and 1 active galactic nucleus. The majority of long-term variables in our sample belong to either Mira or semi-regular types, indicating that long-term variability may be more prominent in post-main sequence phases of late-type stars. The depth of the eclipsing dips of the 26 candidates for eclipsing binaries is equivalent to ~0.61 as the average relative size of the two stars in the binary system. Our results illustrate the power of the KMTNet Supernova Program for future studies of variable objects.

• Journal of Power Electronics
• /
• v.12 no.2
• /
• pp.276-284
• /
• 2012

AC/AC power conversion is widely used to feed AC loads with a variable voltage and/or a variable frequency from a constant voltage constant frequency power grid or to connect critical loads to an unreliable power supply while delivering a very balanced and accurate sinusoidal voltage system of constant amplitude and frequency. The load specifications will clearly impose the requirements for the inverter stage of the power converter, while wider ranges of choices are available for the rectifier. This paper investigates the utilization of a buck-type current source rectifier as the active front-end stage of an AC/AC converter for applications that require an adjustable DC-link voltage as well as elimination of the low-frequency common mode voltage. The proposed solution is to utilize a combination of two or more zero current vectors in the Space Vector Modulation (SVM) technique for Current Sources Rectifiers (CSR).

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.822-823
• /
• 2007

It is easily can be expected that Korea cannot be free under the regulation, because Korea is one of the major $CO_2$ emitter in the world. Even though Korea currently doesn't have any obligation to mitigate the carbon emission, power industry needs to study the effect of that. this paper aims to analyze the change of economic loading order for generation dispatch by various carbon price, looking at each plant's or generator's variable generation cost per unit electricity(kWh) that consists of basic generation price calculated by automatic generation system planning model, WASP 4.0, and $CO_2$ price per unit electricity generation.

• Journal of Korean Institute of Industrial Engineers
• /
• v.24 no.3
• /
• pp.333-343
• /
• 1998

This paper proposes variable stream and sample size(VSSS) group control charts in which both the number of streams selected for sampling and sample size from each of the selected streams are allowed to vary based on the values of the preceding sample statistics. The proposed charts select a small portion of streams and take samples of size n = 1 if both the largest and smallest of sample means fall between the lower and upper threshold limits, and select a large portion of streams and take samples of size n > 1 otherwise. A Markov chain approach is used to derive the formulas for evaluating the performances of the proposed charts. Numerical comparisons are made between the VSSS and fixed stream and sample size(FSSS) group control charts.

• Journal of Fashion Business
• /
• v.9 no.6
• /
• pp.1-11
• /
• 2005

The purpose of this study were to examine how people categorize obese individuals and if they have stereotyping about obese individuals. Twenty-five female volunteer subjects participated in this study. Subjects were undergraduate students in Textiles and Clothing courses at a midwestern university, US. Subjects were asked to give their one-word responses to four statements or questions regarding their impressions of six stimuli. The six stimuli consisted of magazine photographs of women; the magazines were general interest and fashion publications. Subjects then recorded their answers in the boxes for each of the six pictures. As the results, the relevant question as to whether or not more negative attributes would be assigned to the obese model's photographs was confirmed for the Description of Model variable, but not for the Personality of Model or for the Liking the Model variables. There was significant difference in means between the positive and negative descriptions of the Description of Model variable in the direction of negativity toward the obese group seems to confirm that, not only do people categorize others based on appearance, but there was a tendency to favor the average-size group and to view as negative the obese group.

• Journal of Sport and Applied Science
• /
• v.4 no.4
• /
• pp.27-32
• /
• 2020

Purpose: This study sought to explore the effects of air pollution on professional sports in South Korea. Research design, data, and methodology: The dependent variable, the number of attendances, was comprised of 2013-2017 K-league, 2015-2017 KBO, 2014-2017 KBL regular season games, resulting in 1,063, 2,121, 810 individual match-level observations, respectively. With the actual data collected from each place across the country, we created a categorical variable which identify the air quality index divided into four categories by K-eco (i.e., good, moderate, unhealthy, hazardous). To analyze data, ANOVA was employed. Results: First, there was a significant group effect on K-league attendance. Second, there was a significant group effect of KBO attendance. Lastly, there was a significant group effect on KBL attendance. Conclusions: Summary of above results showed that each professional sport leagues' attendance was significantly different depending on the levels of air pollution. Implications were also discussed. Keywords: air pollution, sport spectatorship, professional sports.

• Journal of Korean Academy of Nursing
• /
• v.12 no.2
• /
• pp.1-26
• /
• 1982

The main purpose of this study was to test the effect of the structured information on the sleep amount of the patients undergoing open heart surgery. This study has specifically addressed to the Following two basic research questions: (1) Would the structed in formation influence in the reduction of sleep disturbance related to anxiety and Physical stress before and after the operation? and (2) that would be the effects of the structured information on the level of preoperative state anxiety, the hormonal change, and the degree of behavioral change in the patients undergoing an open heart surgery? A Quasi-experimental research was designed to answer these questions with one experimental group and one control group. Subjects in both groups were matched as closely as possible to avoid the effect of the differences inherent to the group characteristics, Baseline data were also. collected on both groups for 7 days prior to the experiment and found that subjects in both groups had comparable sleep patterns, trait anxiety, hormonal levels and behavioral level. A structured information as an experimental input was given to the subjects in the experimental group only. Data were collected and compared between the experimental group and the control group on the sleep amount of the consecutive pre and post operative days, on preoperative state anxiety level, and on hormonal and behavioral changes. To test the effectiveness of the structured information, two main hypotheses and three sub-hypotheses were formulated as follows; Main hypothesis 1: Experimental group which received structured information will have more sleep amount than control group without structured information in the night before the open heart surgery. Main hypothesis 2: Experimental group with structured information will have more sleep, amount than control group without structured information during the week following the open heart surgery Sub-hypothesis 1: Experimental group with structured information will be lower in the level of State anxiety than control group without structured information in the night before the open heart surgery. Sub-hypothesis 2 : Experimental group with structured information will have lower hormonal level than control group without stuctured information on the 5th day after the open heart surgery Sub-hypothesis 3: Experimental group with structured information will be lower in the behavioral change level than control group without structured information during the week after the open heart surgery. The research was conducted in a national university hospital in Seoul, Korea. The 53 Subjects who participated in the study were systematically divided into experimental group and control group which was decided by random sampling method. Among 53 subjects, 26 were placed in the experimental group and 27 in the control group. Instruments; (1) Structed information: Structured information as an independent variable was constructed by the researcher on the basis of Roy's adaptation model consisting of physiologic needs, self-concept, role function and interdependence needs as related to the sleep and of operational procedures. (2) Sleep amount measure: Sleep amount as main dependent variable was measured by trained nurses through observation on the basis of the established criteria, such as closed or open eyes, regular or irregular respiration, body movement, posture, responses to the light and question, facial expressions and self report after sleep. (3) State anxiety measure: State Anxiety as a sub-dependent variable was measured by Spi-elberger's STAI Anxiety scale, (4) Hormornal change measure: Hormone as a sub-dependent variable was measured by the cortisol level in plasma. (5) Behavior change measure: Behavior as a sub-dependent variable was measured by the Behavior and Mood Rating Scale by Wyatt. The data were collected over a period of four months, from June to October 1981, after the pretest period of two months. For the analysis of the data and test for the hypotheses, the t-test with mean differences and analysis of covariance was used. The result of the test for instruments show as follows: (1) STAI measurement for trait and state anxiety as analyzed by Cronbachs alpha coefficient analysis for item analysis and reliability showed the reliability level at r= .90 r= .91 respectively. (2) Behavior and Mood Rating Scale measurement was analyzed by means of Principal Component Analysis technique. Seven factors retained were anger, anxiety, hyperactivity, depression, bizarre behavior, suspicious behavior and emotional withdrawal. Cumulative percentage of each factor was 71.3%. The result of the test for hypotheses show as follows; (1) Main hypothesis, was not supported. The experimental group has 282 minutes of sleep as compared to the 255 minutes of sleep by the control group. Thus the sleep amount was higher in experimental group than in control group, however, the difference was not statistically significant at .05 level. (2) Main hypothesis 2 was not supported. The mean sleep amount of the experimental group and control group were 297 minutes and 278 minutes respectively Therefore, the experimental group had more sleep amount as compared to the control group, however, the difference was not statistically significant at .05 level. Thus, the main hypothesis 2 was not supported. (3) Sub-hypothesis 1 was not supported. The mean state anxiety of the experimental group and control group were 42.3, 43.9 in scores. Thus, the experimental group had slightly lower state anxiety level than control group, howe-ver, the difference was not statistically significant at .05 level. (4) Sub-hypothesis 2 was not supported. . The mean hormonal level of the experimental group and control group were 338 ㎍ and 440 ㎍ respectively. Thus, the experimental group showed decreased hormonal level than the control group, however, the difference was not statistically significant at .05 level. (5) Sub-hypothesis 3 was supported. The mean behavioral level of the experimental group and control group were 29.60 and 32.00 respectively in score. Thus, the experimental group showed lower behavioral change level than the control group. The difference was statistically significant at .05 level. In summary, the structured information did not influence the sleep amount, state anxiety or hormonal level of the subjects undergoing an open heart surgery at a statistically significant level, however, it showed a definite trends in their relationships, not least to mention its significant effect shown on behavioral change level. It can further be speculated that a great degree of individual differences in the variables such as sleep amount, state anxiety and fluctuation in hormonal level may partly be responsible for the statistical insensitivity to the experimentation.

• Physical Therapy Korea
• /
• v.12 no.4
• /
• pp.7-11
• /
• 2005

The purposes of this study were to investigate the effects of variability of training on the acquisition of motor skill of closed loop type tracking task using Rotary Pursuit, and to determine if there was a bilateral transfer effect to the non-dominant hand following practice with the dominant hand. Twelve healthy volunteer students (5 males and 7 females, aged 25 to 37) were randomly divided into a constant practice group and a variable practice group. A photoelectric rotary pursuit apparatus with stop clock and repeat cycle timer by Lafayette Instrumentation Co. was used for this study. Rotary pursuit is a closed loop task in which a subject attempts to keep a photoelectric stylus on a lighted target in motion. Subjects performed the clockwise circular pursuit task while standing. Experimental procedure was divided into three sessions, namely, pre-test, training, and post-test. The constant group practiced all 60 trials at 30 rpm. Variable practice group did a varied practice session with 15 trials at speeds of 20 rpm, 26 rpm, 34 rpm, and 46 rpm. No one in either group practiced with their non-dominant arm. A Mann-Whitney test and a Wilcoxon Signed Ranks test were used for statistical analyses. The results of this study showed no different training effect between groups on the post-test with the dominant hand. However, bilateral transfer effect of rotary pursuit task between hands was demonstrated. Possible mechanisms are discussed.

• Proceedings of the SAREK Conference
• /
• 2007.11a
• /
• pp.328-333
• /
• 2007

The purpose of this study is modelling of system air-conditioner for TRNSYS. System air-conditioner is operated by a variable capacity compressor and accommodated by multiple evaporators. By reason of these feature, realizing performance of system air-conditioner for TRNSYS was incomplete. In this study performance data of system air-conditioner and control logics are used to make system air-conditioner module for TRNSYS. Performance data contains total capacity, power input and capacity index of system air-conditioner. The simulation was carried out in a mode of temperature level control using TRNSYS 16. The simulation shows that the system air-conditioner model operate variable capacity and can compute capacity index and power input of system.

• The Korean Journal of Pain
• /
• v.37 no.1
• /
• pp.34-40
• /
• 2024

Background: This study aimed to evaluate the efficacy of pulsed radiofrequency applied using transcutaneous electrodes in carpal tunnel syndrome (CTS). Methods: After randomization, the patients received two cycles of noninvasive pulsed radiofrequency (NiPRF), once weekly, or splinting (the control group) for three months. Clinical evaluations were recorded at baseline and weeks 4 and 8. The Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) was used to determine the functional status and symptom severity. Results: Sixty-two patients were followed up for three months. There was no difference between the groups in the BCTQ scores before and after treatment. The NiPRF group found a significant difference between the BCTQ measurements at all time intervals (paired sample t-test; P < 0.001). In the splint group, there was a significant difference only between the basal-1st month and basal-3rd month (paired samples t-test; P < 0.001). The main effect of the time variable was statistically significant (ANOVA; P < 0.001), but the group variable was not. There was no correlation between the BCTQ results measured at any time and the electroneuromyelogragphy findings in either group. Conclusions: NiPRF effectively improves symptoms and functionality in patients with CTS for up to 3 months. Thus, NiPRF can be considered an easy, safe, and useful alternative treatment modality for CTS.