• Research in Community and Public Health Nursing
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• v.17 no.2
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• pp.273-282
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• 2006

Purpose: This study was to evaluate the effects of smoking prevention education on primary school students. Method: This study used a nonequivalent control group pretest-posttest design. The subjects were 189 6th graders of two primary schools, of them, 97 were assigned to the experimental group and 92 were assigned to the control group. Smoking prevention education was applied in 7 sessions for 40 minutes every week. Survey was conducted before and one week after the smoking prevention education to examine student's knowledge of smoking, attitude, and smoking cessation intention. The data were analyzed by descriptive statistics and $x^2-test$, t-test using the SPSS Win 10.0 program. Results: After the completion of the smoking prevention education, there were significant differences between the experimental group and the control group in smoking knowledge (t=2.651, p=.009), but smoking attitude (t=-.492, p=.623) and smoking cessation intention (t=-.425, p=.671) were not statistically significant between the two groups. Conclusion: The smoking prevention education for primary school students increased their knowledge on smoking but didn't have any significant impact on changing their smoking attitude and smoking cessation intention. Further study on longitudinal effect is recommended and the smoking prevention education should be provided continuously at school.

• Korean Journal of Adult Nursing
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• v.12 no.3
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• pp.334-344
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• 2000

The purpose of this research was to examine the effect of support group intervention on the various adaptations of primary family caregivers caring for Cerebro- Vascular Accident patients. The nonequivalent control group pretest-posttest design within the framework of Lazarus & Folkman's stress-adaptation model was used for this experimental study. The subjects were 86 primary family caregivers caring for Cerebro- Vascular Accident patients at K hospital in Taegu, D herbal hospital in Kyung Ju, H hospital in Pohang from March, 1998 to July, 1998. Among 86 subjects, 43 were placed in an experimental group and 43 in a control group. The experimental group was treated by researcher who administered informational and emotional support group intervention once a week over a five weeks period. The data were collected through interviews. Collected data was analized by means of a chi-square test, t-test, ANCOVA, and Pearson correlation coefficient. The results of this research were as follows: 1. Physical, emotional, and social adaptation scores in the experimental group were revealed to be significantly higher than those of the control group. 2. There was significant positive correlation among physical health, subjective burden, depression and objective burden. Accordingly, it is concluded that informational and emotional support group intervention was a useful nursing intervention on the various adaptations of primary family caregivers caring for Cerebro-Vascular Accident patients.

• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.528-537
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• 2008

Primary frequency control(PFC) has the ability to regulate short period random variations of frequency during normal operation conditions and also to respond rapidly to emergencies. However, during the past decade, numerous significant sized blackouts occurred worldwide that resulted in serious economic losses. Therefore, the conclusion has been reached that the ability of the current PFC to meet an emergency is poor, and security of power systems should be improved. An alternative to enhance the PFC and thus security is to store excessive amounts of energy during off-peak load periods in efficient energy storage systems for substituting the primary control reserve. In this sense, superconducting magnetic energy storage(SMES) in combination with a static synchronous compensator(STATCOM) is capable of supplying power systems with both active and reactive powers simultaneously and very rapidly, and thus is able to enhance the security dramatically. In this paper, a new concept of PFC based on incorporating a STATCOM-SMES is presented. A complete detailed model is proposed and a new control scheme is designed, comprising an enhanced frequency control scheme, and a fully decoupled current control strategy in d-q coordinates with a novel controller to prevent dc bus capacitors voltage drift/imbalance. The performance of the proposed control schemes is validated through digital simulation carried out using MATLAB/Simulink.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1254-1266
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• 2024

This study investigates the application of supercritical carbon dioxide (S-CO₂) direct-cycle micro modular reactors (MMRs) in primary frequency control (PFC), which is a scenario characterized by significant load fluctuations that has received less attention compared to secondary load-following. Using a modified GAMMA + code and a deep neural network-based turbomachinery off-design model, the authors conducted an analysis to assess the behavior of the reactor core and fluid system under different PFC scenarios. The results indicate that the acceptable range for sudden relative electricity output (REO) fluctuations is approximately 20%p which aligns with the performance of combined-cycle gas turbines (CCGTs) and open-cycle gas turbines (OCGTs). In S-CO₂ direct-cycle MMRs, the control of the core operates passively within the operational range by managing coolant density through inventory control. However, when PFC exceeds 35%p, system control failure is observed, suggesting the need for improved control strategies. These findings affirm the potential of S-CO₂ direct-cycle MMRs in PFC operations, representing an advancement in the management of grid fluctuations while ensuring reliable and carbon-free power generation.

• The Journal of the Korean dental association
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• v.15 no.3
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• pp.209-214
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• 1977

The author extracted 300 children as a control group and 300 children as an observation group from Korean primary school children which were aged 9 to 11, and surveyed the dental caries experience and oral hygiene condition. Children in a control group had not been served wit school meal. On the other hand, children in an observation group were served with school meal. The average number of caries experienced permanent teeth per mouth and the oral hygiene indices were calculated from the collected data and compared with each other. The obtained results were as follows. 1. The DMFT rate was 15.93% in the observation group and 10.33% in the control group. 2. The Oral Hygiene Index was 1.04 in the observation group and 1.60 in the control group. 3. It couldn't be made a decision that school meal service was direct cause to increase the occurrence of dental caries on the permanent teeth in Korean primary school children.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2007.11a
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• pp.464-468
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• 2007

In cognitive radio systems, secondary users, unlicensed users, can use primary users' spectrum to increase spectrum efficiency. At that time, the systems must satisfy primary users' QoS. When secondary users use cognitive radio systems, secondary users communication can be terminated, because of satisfying primary users' QoS. However, secondary users' communication terminating is not good for both secondary users and whole systems. So, cognitive radio systems need an efficient algorithm for secondary users of admission control and keeping connections. In this paper, we present an algorithm which consist of two part, admission control and connections control.

• Journal of information and communication convergence engineering
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• v.12 no.2
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• pp.97-103
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• 2014

In spectrum sensing, there is a tradeoff between the probability of missed detection and the probability of a false alarm according to the value of the sensing threshold. Therefore, it is important to determine the sensing threshold suitable to the environment of cognitive radio networks. In this study, we consider a cognitive radio-based ad hoc network where secondary users directly communicate by using the same frequency band as the primary system and control their transmit power on the basis of the distance between them. First, we investigate a condition in which the primary and the secondary users can share the same frequency band without harmful interference from each other, and then, propose an algorithm that controls the sensing threshold dynamically on the basis of the transmit power of the secondary user. The analysis and simulation results show that the proposed sensing threshold control algorithm has low probabilities of both missed detection and a false alarm and thus, enables optimized spectrum sharing between the primary and the secondary systems.

• Nuclear Engineering and Technology
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• v.20 no.1
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• pp.1-8
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• 1988

During power plant operation, the flow rate from the CVCS makeup system is estimated using the continuity equation and mass balance equation, when the primary loop boron concentration change is required due to the power transient. For this purpose, primary loop, pressurizer and VCT(volume control tank)(in CVCS) are modeled by three control volumes which contain each mass and boron concentration. Connecting pipes between primary loop, pressurizer and CVCS are also modeled by time delay. Calculation for 14-2-6-2 (power 100-50-100) load follow case (at EOL, for KNU 7) is made using these models.

• KEPCO Journal on Electric Power and Energy
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• v.4 no.2
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• pp.107-114
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• 2018

In recent years, ESS (Energy Storage System) has been widely used in various parts of a power system. Especially, due to its fast response time and high ramp rate, ESS is known to play an important role in regulating grid frequency and providing rotational inertia. As the number of installed and commercially operating ESSs increases, the reliability becomes an important issue. This paper introduces control schemes and presents its test method for grid-connected ESS for primary frequency regulation. The test method allows to verify the control operation in the individual operation mode and state. A validation of the method through actual ESS test in a electrical substation is presented in the case study section.

• Journal of the Korean Society of School Health
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• v.15 no.2
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• pp.249-261
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• 2002

This study was a research study to find out the real picture and practice of student obesity control by primary, middle and high school school nurses. The study sampled 196 school nurses working in the Busan City and Northern Gyungsang Province, who agreed on the purpose of the study. When it comes to the study process, at the meeting of the whole school nurses, the researcher explained the purpose of the study and asked them to complete questionnaires and return on the spot. The study is designed to provide basic data for school nurses in field to systematically and efficiently control student obesity by examining perception of school obesity control and the real picture or practice of obesity control as well as its problems. The study used SPSS 10.0 to analyze data. The results are as follows: Annual plans about obesity control appeared significant at the primary school, 89.3%, higher than 77.3% of the middle and high school(p<0.05). Annual project evaluation showed a significant difference by regions, 56.0% of metro cities vs. small cities(p<0.01). The number of measuring weight of obese students was higher at the primary school than at the middle and high school(p<0.05). Also small cities conducted the weight measurement more often than metro cities(p<0.001). Among the health education methods for obesity, counseling appeared statistically significant(p<.01). The health education showed a significant difference in more experienced school nurses. Among the educational media, environment postings were used at the primary school, 24.0%, higher than 5.3% of the middle and high school. It showed a significant difference(p<.001). OHP or epidiascopes were used at the primary school, 36.4%, significantly higher than the middle and high school(p<.001). In addition, computer was used at the primary school, 21.5%, higher than the middle and high school(p<.05). Problems of obesity education data included a lack of textbooks and programs and a short of educational media. However it didnt show a significant difference in schools or in regions. Counseling activities for obesity showed a significant difference in schools(p<.01) and in regions(p<.001). When parents with obese students were in counseling, those in their 20s used home correspondence and those in their 30s and 40s used phone call(p<.01). The rate of equipment to measure obesity was higher at the middle and high school than the primary school, showing a significant difference(p<.001). Therefore, regular health education curriculums for school nurses should be systematically created to promote student health. Furthermore, it needs to make standard textbooks for health education by grades as well as by levels and to develop various educational programs and educational media.