• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.361-365
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• 2004

This paper describes the various characteristics of voltage sags which can affect the functions of three-phase induction motors that are mostly used in the power distribution systems. These assorted characteristics include motor speed losses, voltage recovery, motor reacceleration, and transient characteristics. An experimental study on the induction motor behaviors was also carried out to confirm these impacts. In addition sequential voltage sags with short durations were considered and investigated. The results show that the occurrence of the second voltage sag after the first one may affects the induction motor adversely.

• Proceedings of the KIEE Conference
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• summer
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• pp.45-47
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• 2004

This paper describes the various characteristics of voltage sags which can affect the functions of three-phase induction motors that are mostly used in the power distribution systems. These assorted characteristics include motor speed losses, voltage recovery, motor reacceleration, and transient characteristics. An experimental study on the induction motor behaviors was also carried out to confirm these impacts. In addition, sequential voltage sags with short durations were considered and investigated. The results show that the occurrence of the second voltage sag after the first one may affects the induction motor adversely.

• Bulletin of the Korean Chemical Society
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• v.21 no.11
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• pp.1077-1084
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• 2000

The dipolar effect of neighboring protons that are not directly bonded to the carbon of interest on coupled carbon-13 relaxation in a simple organic molecule has been studied by comparing the relaxation behaviors of labeled carbon-13 in $Br13CH_2COOH$ with those in $BrCH_213COOH.$ Various pulse sequences, such as coupled inversion recovery pulse sequence, J-negative and J-positive pulse sequence, and nonselective and selective proton ${\pi}pulse$ sequence, were employed to perform the required coupled spin relaxation experiments. To gain information on various spectral densities, including that of dipolar-CSA cross correlation, the experiments were performed on two different spectrometers, operating, respectively, at 50.31 and 125.51MHz for 13C. The magnitude of CH dipolar spectral densities for $BrCH_213COOH$ was found to be about 8% of those for $Br13CH_2COOH$, which means the effect due to the protons not directly bonded to the carbon of interest is small but not completely negligible.

• Nuclear Engineering and Technology
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• v.53 no.10
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• pp.3352-3358
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• 2021

Aiming at selective adsorption and separation of Y(III) from the Y(III)-Sr(II) group in acid solution, a silica-based TODGA impregnated adsorbent [(TODGA+1-dodecanol)/SiO₂-P-F600] has been prepared. Batch adsorption experiments were conducted under the effect of contact time, acid concentration, solution temperature, and adsorption capacity etc. Chromatography recovery of more than 90% Y(III) was successfully achieved under elution with 0.01 M DTPA solution in nitric acid adsorption system, and 0.1 M HCl solution in hydrochloride adsorption system, respectively.

• Journal of Hydrogen and New Energy
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• v.30 no.3
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• pp.289-295
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• 2019

Effects of various reaction factors such as pressure, time, and temperature on clathrate formation were investigated for hydroquinone with $CO_2$ and $N_2$. Experimental and spectroscopic results indicate that $CO_2$ plays more preferential role in forming hydroquinone clathrates than $N_2$. These results can be used in application of selective $CO_2$ separation from flue gases with the formation of clathrate compounds.

• Archives of Metallurgy and Materials
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• v.65 no.4
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• pp.1341-1344
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• 2020

In this study, a simple and effective way to fabricate highly porous scaffolds with controlled porosity and pore size is demonstrated. Ti-7Zr-6Sn-3Mo shape memory alloy fibers were prepared through a melt overflow process. The scaffolds with porosity of 65-85% and large pores of 100-700 ㎛ in size were fabricated by sintering the as-solidified fibers. Microstructures and transformation behaviors of the porous scaffolds were investigated by means of SEM, DSC and XRD. The scaffolds were composed of β phase at room temperature. Superelasticity with the superelastic recovery strain of 7.4% was achieved by β ↔ α" phase transformation. An effect of porosity on mechanical properties of porous scaffolds was investigated by using compressive test. As the porosity increased from 65% to 85%, elastic modulus and compressive strength decreased from 0.95 to 0.06 GPa and from 27 to 2 MPa, respectively.

• Korean Journal of Community Nutrition
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• v.23 no.4
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• pp.289-301
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• 2018

Objectives: The aim of this study was to examine the current status of consumption of energy drinks among college students and investigate the effects of general environmental factors, health behavior factors, caffeine knowledge levels, and perceived stress levels on consumption of energy drinks. Methods: A survey was conducted among a total of 479 college students in Gwangju, using self-administered questionnaires. The questionnaire consisted of items about general environmental factors, health behavior, caffeine knowledge, perceived stress, and energy drink consumption behaviors. Results: 69.1% of participants experienced consumption of energy drinks, and specifically 82.8% of male students and 54.1% of female students experienced consumption of energy drinks (p<0.001). The reasons for drinking energy drinks were found to be recovery from fatigue, curiosity, taste, habit, thirst relief, and stress relief. In addition, 40.7% of participants experienced drinking energy drinks mixed with alcohol, and specifically 48.6% of male students and 27.4% of female students reported drinking energy drinks with alcohol (p<0.001). Moreover, 51.5% of participants responded that they experienced the effects of energy drinks, 31.9% reported experiencing adverse effects, and 41.1% were found to perceive the health risks. As a result of the assessment of caffeine knowledge, the participants showed a high level of knowledge of the arousal effect (77.7%) and the concentration increasing effect (70.8%) of caffeine, whereas they exhibited a low level of understanding of the health problems due to caffeine (32.6%) and adequate caffeine intake levels (24.4%). The higher levels of consumption experience of energy drinks was associated with higher body mass indexes (BMI) (p<0.01), higher academic years (p<0.01), lower levels of interest in health (p<0.05), smoking (p<0.001), alcohol consumption (p<0.05), and higher levels of perceived stress (p<0.05). Conclusions: The risk groups related to consumption of energy drinks among college students were identified as male students rather than female students, students in the third or fourth year of study associated with increased stress levels, and students with negative health behaviors. Therefore, support for diverse health and nutrition education for college students is required along with the improvement of internal and external environments of schools in order for college students to manage increased stress levels due to the schoolwork and preparation for employment and maintain positive health behaviors.

• Asia pacific journal of information systems
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• v.20 no.1
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• pp.57-79
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• 2010

In a virtual community, one can possess multiple identities and pretend to be different by creating self-identity in contrast with his or her actual self. Does false identity undermine the qualitative growth of a virtual community by reducing members' accountability? Or does it stimulate their contributive behaviors by ensuring freedom of speech? It is imperative to understand the effects of multi-identity considering the distinct properties of a virtual community in which people easily change their identities at little or no cost. To answer these questions, we adopted the concept of self-discrepancy from the social psychology theory rooted in the concept of the self and developed a theoretical model to predict quality of contribution of the individual member in virtual communities. Based on the self-discrepancy theory, we first identified two different domains of the self: (1) an "actual self" that consists of attributes that the person believes he or she currently possesses in real life and (2) a "cyber self" that consists of attributes the person believes he or she possesses in a virtual community. Next, we derived an index for two different types of self-discrepancy by using the differences between the actual and the cyber identities: Personal Self-discrepancy and Social Self-discrepancy. Personal Self-discrepancy reflects the degree of discrepancy between actual and cyber identity regarding a person's intelligence, education, and expertise. Social Self-discrepancy reflects the degree of discrepancy between actual and cyber identity regarding a person's morality, sociability, and accordance with social norms. Finally, we linked them with sense of virtual community, perceived privacy rights, and quality of contribution to examine how having a multi-identity influences an individual's psychological state and contributive behaviors in a virtual community. The results of the analysis based on 266 respondents showed that Social Self-discrepancy negatively influenced both the Sense of Virtual Community and Perceived Privacy Rights, while Personal Self-discrepancy negatively influenced only Perceived Privacy Rights, thereby resulting in reduced quality of contribution in virtual communities. Based on the results of this analysis, we can explain the dysfunctions of multi-identity in virtual communities. First, people who pretend to be different by engaging in socially undesirable behaviors under their alternative identities are more likely to suffer lower levels of psychological wellbeing and thus experience lower levels of sense of virtual community than others. Second, people do not perceive a high level of privacy rights reflecting catharsis, recovery, or autonomy, even though they create different selves and engage in socially undesirable behaviors in a virtual community. Third, people who pretend to be different persons in terms of their intelligence, education, or expertise also indirectly debase the quality of contribution by decreasing perceived privacy rights. The results suggest that virtual community managers should pay more attention to the negative influences exercised by multi-identity on the quality of contribution, thereby controlling the need to create alternative identities in virtual communities. We hope that more research will be conducted on this underexplored area of multi-identity and that our theoretical framework will serve as a useful conceptual tool for all endeavors.

• Journal of Korean Academy of Nursing
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• v.30 no.1
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• pp.7-17
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• 2000

The purpose of this study is to affect health improvement of adolescent, to understand behavioral causes follow adolescent's drug abuse, to understand recovery and rehabilitaton process of adolescent drug abuser. The data are collected through open questionnaire and interview of 25 adolescents from the experienced drug abuse 16 students(male 8, female 8) in two vocational high schools and admissing adolescents 9 person in Alcohol-Drug Addiction Care Centre in Seoul from June 28th to August 31st, 1994. The collected data are arranged and explained through categorizing method stated contents about motives, causes, experiences and effected behaviors for using the drugs of drug abuser adolescents. DRUG USING MOTIVATION They are almost first son and daughter in their family. In their conversation person, male converses to their mother well, but female does not converse to their parents include family. Both groups respond positively to companionship and attitude to other, but negatively to self-confidence and actualizing attitude. They hope always peace of family and want to do their best for their life. In school group, hard and difficult things are school life and family problems, also using the drugs for resolving the them. About drug using behaviors, male responds to bad habbit and shamfull, but female is unconcerned with drug using attitude. The first background of drug using, male gets to use because of curiosity and to be induced from friends or seniors, but female gets to use for feminine beauty(thin body) and escape from reality. Used the drugs, male uses frequently Bond, Butane-Gas among inhalation materials and also marijuana, but female uses various diuretics. The times of drug using, both groups repond to use during the chaging of emotion or filling with stress. The place of drug using, both groups take drugs in vacant houses or in the mountain. The frequency of drug using, they use almost once in a day and they use mostly alone or drug user in friends. Experienced mental changing after drug using, which is fantasy, ecstasy, anxiety and suicidal feeling, and experienced physical changing after drug using, which is elevating sense, headach, abdominal pain, dyspnea and chaging of skin colour and reddish. They coincide with inconvenience feeling due to drug using. RECOVERY AND REHABILITATION PROCESS OF DRUG USING ADOLESCENTS The reason for reforming drug using behavior and attitude, both groups respond to reforming for oneself and social life. The difficult things during the stop to using drugs, all of them responed to family problems, friends problems and temptation and impulse. As for stop to using drug, they need good advise, understandable attitude and family love. But they do not need to be stigmatized, scolding, over protect and ridicule of friends. Also they entreat continuous understanding, advise, concern and the method for resolving stress. For the friends to want to use the drug, they will talk about the stories of their personal experiences and for the friends to stop to using the drug, they will consider for them how to stop. From the theses results, drug users understand personal problems due to drug using, and consider about why to stop and how to stop. Also drug users need to resolve the family problems, personal problems, stress and temptations or impulses. Accordingly this paper suggests that drug users in adolescents need understandable and acceptable atitudes, loving and tenderness, continuous advice and concern, and hopes for life.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.4
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• pp.44-52
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• 2003

Shape memory alloys (SMA) are often used in smart structures as active components. Their ability to provide large recovery forces and displacements has been useful in many applications, including devices for artificial muscles, active structural acoustic control, and shape control. Based on the 3-dimensional SMA constitutive equation in this paper, the radial displacement control of externally pressurized circular and semicircular composite cylinders under external pressure with a thin SMA layer bonded on its inner surface or inserted between composite layers in investigated using 3-dimensional finite element analysis. Upon actuation through resistive heating, SMAs start to transform from martensitic into austenitic state, simultaneously recover the prestrain, and thus cause the composite cylinders to go back to their original shapes of the cylinder cross-sections.