• Journal of the Korean Society of Systems Engineering
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• v.18 no.2
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• pp.58-74
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• 2022

Deterministic accident analysis plays a central role in the nuclear power plant (NPP) safety evaluation and licensing process. Traditionally the conservative approach opted for the point kinetics model, expressing the reactor core parameters in the form of reactivity and power tables. However, with the current advances in computational power, high fidelity multi-physics simulations using real-time code coupling, can provide more detailed core behavior and hence more realistic plant's response. This is particularly relevant for transients where the core is undergoing reactivity anomalies and uneven power distributions with strong feedback mechanisms, such as reactivity initiated accidents (RIAs). This work addresses a RIA, specifically a control element assembly (CEA) withdrawal at power, using the multi-physics analysis tool RELAP5/MOD 3.4/3DKIN. The thermal-hydraulics (TH) code, RELAP5, is internally coupled with the nodal kinetics (NK) code, 3DKIN, and both codes exchange relevant data to model the nuclear power plant (NPP) response as the CEA is withdrawn from the core. The coupled model is more representative of the complex interactions between the thermal-hydraulics and neutronics; therefore the results obtained using a multi-physics simulation provide a larger safety margin and hence more operational flexibility compared to those of the point kinetics model reported in the safety analysis report for APR1400. The systems engineering approach is used to guide the development of the work ensuring a systematic and more efficient execution.

• Animal cells and systems
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• v.13 no.3
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• pp.267-274
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• 2009

The dissociative culture technique of Aplysia neuron is one of the key methods that have been used for studies of cellular and molecular mechanisms of neuronal functioning. However, despite the advantages this method offers as an experimental model, its technical efficiency has had room for improvement. In this study, we examined certain putative factors that might affect the culture quality. The effects of neuronal damage induced by physical injuries, heat shock, and surface protein degradation were evaluated along with the correlation between the culture quality and animal behavior. As a result, we found that physical injury can be a critical factor that affects culture quality, whereas the heat shock and surface protein degradation had negligible effect on it. In addition, we discovered that siphon retraction time was not a good measurement for healthy neurons. Based on these findings, we suggest here an improved method in which the degree of physical injury is reduced by means of multiple protease treatment.

• Women's Health Nursing
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• v.17 no.2
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• pp.148-156
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• 2011

Purpose: This study was done to explore the rates and methods of contraception among Korean adolescents from 2007 to 2009. Methods: The study was a descriptive study. The data were taken from a web-based survey on risk behavior of Korean youth that was conducted between 2007 and 2009 by the Korea Centers for Disease Control and Prevention. Results: Among adolescents, 4.7% in 2007, 4.6% in 2008, and 4.7% in 2009 reported having had sexual intercourse. In those who had sexual experiences, less than 30% reported consistent use of contraception, whereas more than 45% report no contraceptive use at all. A condom was the most frequently used contraceptive method and its use has increased continuously among contraceptive users. Some of the adolescents were, nevertheless, using unreliable methods such as withdrawal or the rhythm method. Conclusion: The results of this study indicate that most adolescents are not using contraception consistently and some were relying on unreliable contraceptive methods. Efforts to raise awareness about consistent and correct contraceptive use and the importance of dual protection are essential.

• Nuclear Engineering and Technology
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• v.13 no.3
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• pp.153-161
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• 1981

The dynamic behavior of the Ko-ri Unit 1 nuclear reactor following some credible and postulated accidents has been analyzed to a certain extent by means of neutronics and temperature equations formulated in terms of point reactor model. In general, the result of numerical calculation is harnessed to be incorporated in more elaborate models so as to predict transient behavior in a reliable mode as a part of accident analysis. It is shown in the case of power response upon an uncontrolled withdrawal of rod cluster control assembly at hot full power that the point reactor kinetics model proves to be good enough to reproduce the generic features described in the final safety analysis report of the Ko-ri Unit 1.

• Korean Journal of Ecology and Environment
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• v.37 no.4 s.109
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• pp.423-430
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• 2004

This study intended to understand movements of turbid water in selective with drawal reservoirs before and after summer monsoon. Mean rainfall during November-May was low, compared to that during June-October. The reservoir water was discharged through watergates when previous rainfall and inflow exceeded 50 mm and $80\;m^3s^{-1}$, respectively. Intake towers were generally used except for the period of the high runoff. Average turbidity in gown-reservoir showed a difference of 29.9 NTU between premonsoon and postmonsoon. Diameter of particles of turbid water ranged between 0.435 and $482.9\;{\mu}m$. Fine particles such as clay were much denser than the larger particle. In the whole stations, clay component was relatively higher with a proportion of that in the particle distribution. Particle composition of turbid water showed that clay consisted of 94.4-98.9% and silt made of 1.1-5.6%. Analysis on turbid water movements derived from particle distribution showed a linear increase from the deep layer toward the surface layer in lower area of a reservoir. This was closely related with the hydraulic behavior of the reservoir, and heavily affected by the discharges through selective withdrawal towers and watergates. Turbid water originated from stream sediments in the middle area then resuspended in the down-reservoir causing a movement between the surface and middle layers of the reservoir. Therefore, such phenomenon needs to be understood for reservoir water quality management.

• The Journal of the Korea Contents Association
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• v.22 no.7
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• pp.264-275
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• 2022

The purpose of this study is to examine the effects of social withdrawal, depression, aggression, negative parenting attitude as parental factors, friendship as school factors, academic helplessness and smartphone dependence, persistence, etc. on adolescent delinquency experiences as perceived personal factors. was carried out to understand. For this study, first year middle school students in the first year of the Korean Children and Youth Panel Survey (KCPYS 2018) were analyzed. As a result of the study, it was found that depression, aggression, social withdrawal as individual factors of adolescents, negative parenting attitude as parent factors, academic helplessness, negative friendships, smartphone dependence, persistence, etc. as school factors influence delinquent behavior of adolescents. In addition, it was found that smartphone dependence and persistence play a partial mediating role in the process of personal factors, parental factors, and school factors affecting adolescents' delinquency experiences. Based on these results, first, we need to break stereotypes about adolescents and understand the accurate understanding of adolescents' delinquent behaviors and what expectations they have. Second, practical education is required for parents and grandparents for consistent parenting attitudes and effective parenting. Third, a positive self-awareness and correct human relationship formation program should be operated in order to improve the friendship among adolescents. Finally, correct smartphone usage and counseling interventions and prevention programs to alleviate impulsivity are needed.

• Journal of Korean Academy of Nursing
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• v.39 no.6
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• pp.818-828
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• 2009

Purpose: This study was done to develop a cell phone addiction scale for Korean adolescents. Methods: The process included construction of a conceptual framework, generation of initial items, verification of content validity, selection of secondary items, preliminary study, and extraction of final items. The participants were 577 adolescents in two middle schools and three high schools. Item analysis, factor analysis, criterion related validity, and internal consistency were used to analyze the data. Results: Twenty items were selected for the final scale, and categorized into 3 factors explaining 55.45% of total variance. The factors were labeled as withdrawal/tolerance (7 items), life dysfunction (6 items), and compulsion/persistence (7 items). The scores for the scale were significantly correlated with self-control, impulsiveness, and cell phone use. Cronbach's alpha coefficient for the 20 items was .92. Scale scores identified students as cell phone addicted, heavy users, or average users. Conclusion: The above findings indicate that the cell phone addiction scale has good validity and reliability when used with Korean adolescents.

• The Korean Journal of Rehabilitation Nursing
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• v.18 no.1
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• pp.57-66
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• 2015

Purpose: This study aimed to explore and describe nurses' prejudice toward foreigners. Methods: The participants in the current study were 16 nurses who had worked in university hospitals. Data were collected using focus group interviews and an inductive content analysis was conducted with three focus groups. Results: The contents with regard to prejudice toward foreigners were categorized into three themes: prejudice formation, triggers of prejudice and prejudiced behaviors. The participants' prejudice toward foreigners as instigated by appearances, attitudes, or the national economic statuses of foreigners were added to the prejudice which had been formed previously. Prejudiced behaviors included discriminative attitudes, devotion withdrawal, defensive behavior, or derision. Conclusion: The findings of this study indicate that nurses may have positive or negative prejudices toward certain foreigners, which can affect their nursing practice. These findings also warrant the development of programs designed to increase awareness of and reduce nurses' prejudice toward foreigners.

• Sleep Medicine and Psychophysiology
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• v.7 no.1
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• pp.5-9
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• 2000

Several nonpharmacological treatment methods of insomnia and their effects were reviewed. A long-term use of most hypnotics may produce tolerance, dependence, cognitive and psychomotor impairments at daytime, shallow sleep, and rebound insomnia on drug withdrawal. To reduce hypnotic abuse, nonpharmacological strategies have been developed to correct disordered behavioral and cognitive factors. These treatments aim at modifying maladaptive sleep habits, lowering physiological and cognitive arousal levels, and correcting dysfuctional beliefs and attitudes about sleep. These non-pharmacological or cognitive behavior treatments include stimulus control, sleep restriction, relaxation training, sleep hygiene education, cognitive therapy, and light therapy. Among them the stimulus control therapy has been demonstrated most effective as a single treatment or in combination with other treatments. Through nonpharmacological treatments, sleep latency was most significantly reduced and wake time after sleep onset was also reduced. About 50% of insomniacs reported clinical improvements in terms of nearly normalized sleep latency, awakening time, sleep efficiency, and reduction of hypnotic use. Compared to the hypnotic therapy, nonpharmacological treatments are more cost-effective and more readily accepted by patients, and their effects last longer.

• Korean Journal of Child Studies
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• v.15 no.1
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• pp.109-125
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• 1994

The purpose of this study was to validate the IBQ scale (Infant Behavior Questionnaire; Rothbart, 1981). This study examined the validity, reliability and overall tendency of temperamental traits on the IBQ scale. The subjects were 453 mothers with 3-, 6-, 9-, 12-, 15- and 18-month-old infants (232 boys and 221 girls) living in Seoul and Chongju. The IBQ scale, was composed of 56 items (5-point Likert scales), was administered to mothers, using the interview method. Factor analysis revealed that a 6- factor solution was the best fit for the IBQ scale; positive emotionality, attention persistence, approach or withdrawal, negative emotionality, dis tractability and activity. Cronbach's ${\alpha}$ ranged from .61 to .79 for the subscales and .79 for the total scale. It was concluded that the IBQ scale in general is acceptable for use in Korea.