• 한국가시화정보학회지
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• 제21권2호
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• pp.45-54
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• 2023

In the present study, we propose new type of a spinning disk reactor(SDR) with high performance and very convenient structure to make a large scale equipment from lab-scale than the conventional one. A split-disk experimental equipment, based on new type of spinning disk reactor, has been developed to generate an energy to break a bulk of injected gas into smaller gas bubble. Several cases of an experimental observation make it to confirm that a bulk of injecting gas could be continuously break into smaller bubbles. It shows the feasibility to make a scale-up of SDR by using the characteristic of Taylor-Proudman column in rotating flow. A theoretical study on single phase liquid flow is given to predict a liquid induced shear stress, which make the present study to be self-containment.

• 한국환경과학회지
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• 제26권11호
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• pp.1201-1208
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• 2017

Oxidative degradation of chlorinated ethenes was carried out using heat-activated persulfate. The activation rate of persulfate was dependent on the temperature and the activation reaction rate could be explained based on the Arrhenius equation. The activation energy of persulfate was 19.3 kcal/mol under the assumption that the reaction between the sulfate radical and tricholoroethene (TCE) is very fast. Activation could be achieved at a moderate temperature, so that the adverse effects due to high temperature in the soil environment were mitigated. The reaction rate of TCE was directly proportional to the concentration of persulfate, indicating that the remediation rate can be controlled by the concentration of the injected persulfate. The solution was acidized after the oxidation, and this was dependent on the oxidation temperature. The consumption rate of persulfate was high in the presence of the target organic, but the self-decomposition rate became very low as the target was completely removed.

• 한국IT서비스학회지
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• 제17권1호
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• pp.33-45
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• 2018

Recently, many South Korean firms have suffered financial losses and damaged corporate images from the data breaches. Accordingly, a firm should manage their IT assets securely through an information security investment. However, the difficulty of measuring the return on an information security investment is one of the critical obstacles for firms in making such investment decisions. There have been a number of studies on the effect of IT investment so far, but there are few researches on information security investment. In this paper, based on a sample of 76 investment announcements of firms whose stocks are publicly traded in the South Korea's stock market between 2001 and 2017, we examines the market reaction to information security investment by using event study methodology. The results of the main effects indicate that self-developed is significantly related to cumulative average abnormal returns (CAARs), while no significant effect was observed for discloser, investment characteristics and firm characteristics. In addition, we find that the market reacts more favorably to the news announced by the subject of investment than the vendor, in case of investments with commercial exploitation. One of main contributions in our study is that it has revealed the factors affecting the market reaction to announcement of information security investment. It is also expected that, in practice, corporate executives will be able to help make an information security investment decision.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.187-192
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• 2008

A simplified model for an isolated aluminum particle burning in air is presented. Burning process consists of two stages, ignition and quasi-steady combustion (QSC). In ignition stage, aluminum which is inside of oxide film melts owing to the self heating called heterogeneous surface reaction (HSR) as well as the convective and radiative heat transfer from ambient air until the particle temperature reaches melting point of oxide film. In combustion stage, gas phase reaction occurs, and quasi-steady diffusion flame is assumed. For simplicity, 1-dimesional spherical symmetric condition and flame sheet assumption are also used. Extended conserved scalar formulations and modified Shvab-Zeldovich functions are used that account for the deposition of metal oxide on the surface of the molten aluminum. Using developed model, time variation of particle temperature, masses of molten aluminum and deposited oxide are predicted. Burning rate, flame radius and temperature are also calculated, and compared with some experimental data.

• Journal of Radiation Protection and Research
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• 제26권3호
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• pp.287-290
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• 2001

The 9.17MeV gamma-rays from the $^{13}C(p,\;{\gamma})^{14}N,\;^{14}N({\gamma},\;{\gamma})^{14}N$ reactions were measured. The incident 9.17MeV gamma-ray was produced from the $^{13}C(p,\;{\gamma})^{14}N$ reaction at Ep=1.75MeV resonance. The 1.75MeV proton beam was accelerated using the 3MV SNU-AMS Tandetron and 1.7MV KIGAM Tandem accelerators. The enriched 13C target was $121{\mu}g/cm^2$ self-supporting foil, and we used liquid nitrogen as a resonant absorption target. We used a HP-Ge detector with 30% efficiency and less 2keV energy resolution. We developed new method to detect the scattered 9.17MeV gamma-ray from the nitrogen target by using the energy difference between the Doppler shifted gamma-ray from the $^{13}C(p,\;{\gamma})^{14}N$ reaction and the resonant absorbed and rescattered gamma-ray from the $^{14}N({\gamma},\;{\gamma})^{14}N$ reaction.

• International Journal of Human Ecology
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• 제13권1호
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• pp.39-56
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• 2012

This study aims at exploring Korean mothers' beliefs on the development of emotion of their children. In specific, sensitivity and maternal reactions to their children's both negative and positive emotion expressions were explored. Further, associations among maternal sensitivity, maternal reactions and child emotion regulation were examined. A total of 100 Korean mothers whose children were between 6 and 7 years old participated in the study. In order to assess mothers' beliefs about sensitivity, vignettes in a forced-choice format were presented through individual interviews. Mothers' self reported reactions to their children's negative emotions and positive emotions and mothers' perceptions of children's emotion regulation were assessed using questionnaires. Results revealed that Korean mothers endorsed both proactive and reactive sensitivity. However, their sensitivity differed depending on the situation. Mothers tended to endorse either Emotion Focused or Problem Focused reactions to their children's negative emotions. Mothers reported that they were most likely to restrict their child positive emotional expression with explanation in supportive way followed by invalidating through reprimanding it. Mothers' reported Distress Reactions and Punitive Reactions to children's expression of negative emotion were associated with children's liability whereas Emotion-Focused Reaction and Problem-Focused Reaction were associated with children's functional emotion regulation. The results are discussed within a theoretical framework of socialization of emotions.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제26권4호
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• pp.266-272
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• 2015

Objectives : This study examined the impact of peer's suicide on mental health of middle-school students. The aim of this study was to describe the course of posttraumatic stress and grief reaction, suicide ideation, and depression score among adolescents after exposure to peer's suicide and to examine the relationship between posttraumatic stress and other mental health scores in these subjects. Methods : Thirty seven middle school students who were exposed to the suicidal death of a peer completed self-report measures to assess levels of depression, grief reaction, post-traumatic stress, and suicide ideation at 1 month and 8 months after the peer's suicide. Results : There was no significant change in mental health scores between 1 month and 8 months. Level of posttraumatic stress after 8 months was related to acute grief response. Subjects who experienced a clinically significant level of suicidal ideation and posttraumatic stress showed more mental health problems. Conclusion : The results suggested that peer's suicide strongly impacted mental health issues of adolescents at a critical time of adolescent development. Clinicians should perform a thorough evaluation of mental health problems for youth who experienced peer's suicide and help them in management of their grief reaction.

• 자원리싸이클링
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• 제12권4호
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• pp.51-57
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• 2003

케퍼시터용 Ta 분말제조공정에서 발생하는 waste 분말을 이용하여 TaC 분말을 자전고온합성법에 의하여 합성하였다. waste TA는 합성반응의 활성 및 산화방지를 위하여 전처리공정에서 미분쇄 및 탈산처리가 필요하였다. 합성반응에서는 TaC 단일상은 6∼7wt.％C의 조성범위에서 얻을 수 있었다. 또한 반응온도는 시료의 압축력에 영향을 받으며, 압축력 1600psi에서 최고반응온도를 나타냈다.

• 한국재료학회지
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• 제14권12호
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• pp.885-888
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• 2004

$BaMgAl_{10}O_{17}:Eu^{2+}$ for PDP blue phosphor was synthesized using SHS(Self-propagating High temperature Synthesis) method. While Al metal powder was oxidized in this combustion, $Eu_{2}O_3$ was reduced to Eu2+. Therefore the mole ratio of $Al/Al_{2}O_3$ is one of the most important variable of the reaction. When $Al/Al_{2}O_3$ is 2.5/3.75, it has not only appropriate temperature and reaction velocity, but also excellent luminescent property. The sample synthesized in this system has similar characteristics comparing to sample using conventional solid-state reaction.

• 상하수도학회지
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• 제35권1호
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• pp.27-37
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• 2021

Tetracycline is one of the most commonly used as antibiotics for the livestock industry and it is still widely used nowadays. Tetracycline and its metabolites are excreted with excrement, which is difficult to completely removed with conventional sewage treatment, therefore it is apprehended that the tetracycline-resistant bacteria occurs. In this study, the oxidant named ferrate(VI) was used to degrade the tetracycline and investigate the reaction between ferrate(VI) and tetracycline under various aqueous conditions. The highest degradation efficiency of tetracycline occurred in basic condition (pH 10.1 ± 0.1) because of the pKa values of tetracycline and ferrate(VI). The results also showed the effect of water temperature on the degradation of tetracycline was not significant. In addition, the dosage of ferrate(VI) was higher, the degradation of tetracycline and the self-degradation of ferrate(VI) also higher, finally the efficiency of ferrate(VI) was lower. The results said that the various mechanisms effects the reaction of ferrate(VI) oxidation, it required the consideration of the characteristics of the target compound for optimal degradation efficiency. Additionally, intermediate products were detected with LC/MS/MS and three degradation pathways were proposed.