• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.42.2-42.2
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• 2010

Transparent conducting oxides (TCOs) are of significant importance for their applications in various devices, such as light-emitting diodes, thin-film solar cells, organic light-emitting diodes, liquid crystal displays, and so on. In order for TCOs to contribute to the performance improvement of these devices, TCOs should have high transmittance and good electrical properties simultaneously. Sn-doped $In_2O_3$ (ITO) is the most commonly used TCO. However, indium is toxic and scarce in nature. Thus, ZnO has attracted a lot of attention because of the possibility for replacing ITO. In particular, group III impurity-doped ZnO showed the optoelectronic properties comparable to those of ITO electrodes. Al-doped ZnO exhibited the best performance among various doped ZnO films because of the high substitutional doping efficiency. However, in order for the Al-doped ZnO to replace ITO in electronic devices, their electrical and optical properties should further significantly be improved. In this connection, different ways such as a variation of deposition conditions, different deposition techniques, and post-deposition annealing processes have been investigated so far. Among the deposition methods, RF magnetron sputtering has been extensively used because of the easiness in controlling deposition parameters and its fast deposition rate. In addition, when combined with post-deposition annealing in a reducing ambient, the optoelectronic properties of Al-doped ZnO films were found to be further improved. In this presentation, we deposited Al-doped ZnO (ZnO:$Al_2O_3$ = 98:2 wt%) thin films on the glass and sapphire substrates using RF magnetron sputtering as a function of substrate temperature. In addition, the ZnO samples were annealed in different conditions, e.g., rapid thermal annealing (RTA) at $900^{\circ}C$ in $N_2$ ambient for 1 min, tube-furnace annealing at $500^{\circ}C$ in $N_2:H_2$=9:1 gas flow for 1 hour, or RTA combined with tube-furnace annealing. It is found that the mobilities and carrier concentrations of the samples are dependent on growth temperature followed by one of three subsequent post-deposition annealing conditions.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.265-266
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• 2012

의료용 X-ray의 발전에 따라, 영상의 Digital화가 필요하게 되었다. Digital 영상 구현을 위해 다양한 형태의 영상 검출기가 개발되었다. 진단 영상의 조건으로는 구현 시간이 빠르고 해상도가 높아야 한다. 조건에 부합하는 Flat panel 형태의 직접방식과 간접방식 검출기의 개발이 주로 이루어졌으며, X-ray 검출 효율이 높고 공간 분해능이 높은 직접 방식의 검출기에 대한 연구가 활발히 진행되고 있다. 기존 직접방식의 X-ray 검출물질로는 A-Se이 이용되었다. 하지만 A-Se의 경우 낮은 원자번호로 인해 X-ray에 대한효율이 낮으며, 제조 공정과 수율의 문제로 인해 대체 물질의 개발과 공정의 개선이 필요하다. 선행 연구를 통해 X-ray 검출물질의 전기적 특성을 파악을 통해 대체 물질로서 가능성을 알아보았다. 본 연구에서는 기존에 제작된 X-ray 검출물질의 상부전극 증착 물질과 증착법 선정에 대한 연구이다. 선행 연구를 통해 선정된 X-ray 검출물질은 HgI2이다. 상, 하부 전극 선택에 있어 HgI2의 일함수 값(4.15eV)을 고려하여 그와 비슷한 일함수 값을 가진 물질로 전기적 장벽을 제거하여야 한다. 따라서, ITO (일함수 4.45eV)와 Au (일함수 5.1eV)을 선택하였다. ITO의 증착으로 이용된 방법으로는 on-axis 형태의 magnetron plasma sputtering을 이용하였으며, Au의 증착으로 이용된 방법은 Thermal evaporation deposition을 이용하였다. plasma sputtering에 이용된 타겟은 In2O3;SnO2 (조성비:90:10wt%)를 사용하였으며, Chamber의 크기는 넓이 456 ${\phi}cm^2$ 높이 25 cm이며, 로 target과 기판과의 거리는 15cm이다. plasma발생에 필요한 가스로는 Ar과 O2를 이용하였다. 고 진공 환경 조성에 이용된 장비로는 Rotary pump와 Turbo molecular pump이다. plasma 발생 전 진공도는 $3.2{\times}10^{-5}$ Torr, 발생 후 진공도는 $5.1{\times}10^{-5}$ Torr이다. plasma 환경이 조성된 후 증착 시간은 1분 30초이다. Au는 순도 99.999%를 이용하였으며, 이용된 금은 1회 증착에 0.3 g을 이용하였다. Chamber의 넓이 1,444 ${\phi}cm^2$이며, 높이 40 cm, boat와 기판과의 거리는 25 cm이다. 고 진공 환경 조성에 이용된 장비로는 Rotary pump와 diffusion pump를 이용하였다. Au의 승화 전 진공도는 $2.4{\times}10^{-5}$ Torr 증착 시 진공도는 $4.2{\times}10^{-5}$ Torr이며, Boat에 가해준 전압, 전류는 0.97 V, 47 A이며, 증착 시간은 1분 30초이다. 광도전체 층에 각각 증착된 전극의 저항을 통해 증착상태를 판단하였다. DMM (Digital Multimeter)로 1 cm 간격으로 측정된 표면의 저항은 ITO 약 $8{\Omega}$, Au 약 $3{\Omega}$으로 전극으로서 이용이 가능한 상태이다. Au와 ITO가 증착된 HgI2 시편의 전기적 특성은 기존에 이용된 X-ray 변환물질의 성능보다 우수하였다. 하지만 Au와 ITO가 각각 증착된 시편의 전기적 특성은 큰 차이를 보이지 않았다. ITO의 경우 진공 상태에서 이용되는 Gas가 이용되며, Plasma 환경 조성 유지가 어려운 점이 있다. Au전극은 증착 환경 조성이 쉽지만, 전극 물질 이용효율이 떨어지는 단점이 있다. 본 연구를 통해 X-ray 변환물질인 HgI2의 전극물질로 Au와 ITO의 이용가능성을 알아보았다. 두 전극으로 제작된 검출기의 성능은 큰 차이 없이 우수하였고, 전기적 장벽 상태가 낮아 높은 검출 효율을 보였다. 상대적으로 Au 전극의 공정이 간단하고 수율이 높다. 하지만 Au Source의 이용 효율이 떨어지는 단점이 있다. 본 연구의 결과를 통해 공정상의 유리함과 Source의 이용효율을 고려한 분석에 대한 연구가 필요할 것으로 사료된다.

• The Journal of the Korea Contents Association
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• v.20 no.11
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• pp.603-614
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• 2020

The purpose of this study was to classify latent profiles based on SNS addictive tendencies of married women and to examine the effects of age, adult attachment, extrinsic motivation of the fear of missing out and marriage satisfaction. A total of 300 married women who have been using SNS participated in this study. The result indicated that there were three latent profiles for SNS addictive tendencies of married women : (1) high-risk group (2) potential-risk group (3) low-risk group. The high-risk group had high scores in all sub-areas (obsession and withdrawal symptoms, over-communication and immersion, over-consumption). The high-risk group accounted for 24.51% of the total and the potential-risk group was 44.33%, which had the highest proportion of them. While attachment anxiety, attachment avoidance, extrinsic motivation of the fear of missing out, and marriage satisfaction were significant determinants of latent profiles, age was not. This study divided groups according to the characteristics of married women's SNS addiction tendencies and provided implications for counseling and education according to group characteristics, and discussed the need for various research through the development of standardized SNS addiction scale for married women.

• The korean journal of orthodontics
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• v.31 no.2 s.85
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• pp.187-197
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• 2001

The change of the vertical dimension is of fundamental importance to the orthodontist. However, the choice between the two methods of treatment, extraction versus nonextraction, is not clear. It is not verified that the extraction method decreases vertical dimension, or nonextraction methods result in an increase in vertical dimension. The purpose of this study was to evaluate the changes of vertical dimension of face after the orthodontic treatment with standard edgewise technique, and to compare them in relation to facial types and bicuspid extraction. The subjects consisted of 165 orthodontic patients (77 of adolescents, 88 of adults), and was divided into vertical nonextraction (VN) group, vertical extraction (VE) group, horizontal nonextraction (HN) group, horizontal extraction (HE) group. Pre-and Post-treatment cephalograms were taken with standard method, traced, and digitized for each subject. The comparison of the measurements were statistically executed with Student's t-test. The results were as follows : 1. The facial height and molar height were increased after orthodontic treatment in the all groups. 2. No significant difference was found in the facial height change between the vertical and horizontal groups. 3. No significant difference was found in the facial height change between the extraction and nonextraction groups. 4. As the upper molars were extruded in adolescents group and lower molars were extruded in adults group, lower anterior facial height (LAFH) was increased. 5. None of the pretreatment variables correlates to the change of lower anterior facial height (LAFH).

• Clean Technology
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• v.26 no.3
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• pp.211-220
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• 2020

This experimental study investigates the design parameters to achieve ultra low NOx combustion of coal using a 80 kW capacity single-burner furnace. The influence of key design parameters such as SN, overall and burner-zone equivalence ratios, primary/secondary air ratio, overfire air (OFA) ratio were tested for a total of 81 cases. The results showed that weak swirl intensity of the burner leads to higher NOx emission whereas strong swirl intensity accompanies increased CO concentration desipte lower NOx emission. Therefore, finding an appropirate swirl intensity is essential for the burner design. Larger flow rate of secondary air increased NOx emission, whereas smaller flow rate stretches the flame and increased CO emission. The lowest NOx emission of 82 ppm (6% O₂) was achieved at the optimal condition of the present burner deisgn. It is expected to furrther lower the NOx emission by introducing splitting the burner secondary air into three or four streams.

• Journal of Digital Convergence
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• v.10 no.8
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• pp.135-148
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• 2012

This work is intended to investigate how the factors of enterprise mobile SNS affect user satisfaction and continuous use intention through technology acceptance model proposed by Davis. To achieve the purpose, this researcher explored Information Systems Success model proposed by DeLone & McLean, Technology Acceptance Model proposed by Davis, and Model after Acceptance, and on the basis of the investigation, performed a study. For the data of this work, 9 enterprises, each of which has more than 100 employees and is located in Seoul, were chosen, and a questionnaire survey was conducted on their 276 employees who experienced enterprise mobile SNS. As a data collection tool, a structured self-administered questionnaire was used. For data analysis, SPSS 18.0 and AMOS 18.0 were used for applying Structural Equation modelling. According to the results of this work, three factors of enterprise mobile SNS-systematic factor (system quality, information quality, and service quality), user factor (personal innovation and personal familiarity), social factor (social effects and social interaction)-affected user satisfaction and continuous use intention through perceived availability, perceived easiness, and perceived enjoyment. Also, it was found that the direction of effects matched a theoretical prediction. And, it was revealed that the decision variables and mediating variables significantly affected user satisfaction and continuous use intention. Theoretical and practical meanings were discussed for the study result, and some suggestions were made for the issues of this work and future studies.

• Journal of Digital Convergence
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• v.12 no.1
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• pp.295-303
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• 2014

This exploratory study deals with the digital policy proposal through emotional perception of real name SNS and WOM effect. Research was based on the audience trends analysis of the movies having official SNS sites and the movies not having official SNS sites among the opened 90 movies in Korea from 2012 to 2013. Therefore, researchers confirmed that the representative real SNS, facebook was utilized as emotional marketing tools and tried to analyze the effectiveness of SNS critically. The research results are the follows. First, the movies to actively utilize facebook showed statistically significant differences in terms of daily, weekly audience and seat share (occupancy ratio). It is indirectly confirmed that real name SNS such as facebook is much effective in WOM marketing. Second, in the daily trends and weekly trends, the movies showed a similar pattern and above all, the movies to actively take advantage of facebook maintained their audience trends. Thus the government and the corporation have to understand the emotional WOM effect of real name SNS for policy effectiveness. Therefore this study gives the contribution practically for boost up the policy effectiveness through emotional ripple WOM effect of the strength of weak tie of real name SNS.

• The Journal of Society for e-Business Studies
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• v.20 no.1
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• pp.1-22
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• 2015

Due to recent growth in IT industry along with the expansion of smartphone, we came to connect to the Internet wherever and whenever we are. However, this causes negative side effects, though. One of them is a rapid increase of the financial crimes such as the Phishing and the SMishing. There have been many on-going researches about crimes such as Phishing and SMishing to protect users. However, the study about sharing knowledge on SNS to prevent such a crime can be hardly found. Based on social identity theory, we conduct the research about factors on SNS users' intention to share the information security knowledge on SNS. As a result, we found that knowledge provision self-efficacy has a significant impact on self-expression. In addition, it also found out self-expression, awareness about information security and the sense of belonging have a significant impact respectively on the intention to share the information security knowledge on SNS. On the other hand, the altruism didn't have a significant impact to the intention to share information security knowledge on SNS. With this research as a starting point, it seems necessary to expand its range to all types of online community in the future for the generalization of the hypotheses.

• Journal of the Korean Applied Science and Technology
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• v.33 no.3
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• pp.441-448
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• 2016

Heavy metal removal study is conducted from synthetic waste water by reduction and oxidation(redox) reaction of Cu-Zn metal alloy and adsorption reaction of aluminium silicate. Heavy metal whose ionization tendency is smaller than zinc are reducted in an aqueous solution, and the concentration of ionized zinc is reduced by adsorption reaction. The average diameter of metal alloy micro fiber is about $200{\mu}m$, and the surface area is wide enough to get equilibrium in a single cycle treatment. A single cycle treatment of redox reaction of Cu-Zn metal alloy, could remove 100.0 % of Cr(III), 98.0 % of Hg, 92.0 % of Sn and 91.4 % of Cu respectively. An ionization tendency of chromium is very close to zinc, but removal efficiency of chromium by redox reaction is significant. This result shows that trivalent chromium ion is expected to generate hydroxide precipitation with $OH^-$ ion generated by redox reaction. Zinc ion generated by redox reaction is readily removed by adsorption reaction of aluminium silicate in a single cycle treatment. Other heavy metal components which are not perfectly removed by redox reaction also showed very high removal efficiency of 98.0 % or more by adsorption reaction. Aluminium ion is not increased by adsorption reaction of aluminium silicate. That means heavy metal ion removal mechanism by adsorption reaction is turned out to be not an ion exchange reaction, but an adsorption reaction.

• Journal of Digital Convergence
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• v.14 no.10
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• pp.25-32
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• 2016

The current research was to investigate the effects of discussion activities based on Havruta style on elementary school students' social studies communication skills. For this purpose, we examined a comparative study between 5th grade students and other students of partner schools. As research results, first, online classes using video conference equipment and smart devices will enhance the students' interest and participation in class. Second, the Havruta style helps students not only acquire and internalize knowledge by themselves through the course of reciprocal questions and discussions but also improve presentations and participations. Third, it is necessary not only to draft a new lesson plan and to reconstruct the education process for video and online classes but also to develop the classes with a lesson plan after preparations and discussions with colleague teachers; the process of reflection, such as writing a lesson research journal, has a positive effect to improve the quality of cooperative classes. Fourth, using SNS discussion activities to serve as a complementary activity is good, and two teachers can evaluate each of the students' achievement. It is necessary to have a sufficient number of schools where video and online cooperative learning is possible with video equipment provided. To maximize the effect of video and online classes, various studies and teacher trainings are needed. Education office needs to provide a server that enables students in small and large classes to freely engage in cooperative learning.