• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.60-60
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• 1999

단결정 다이아몬드의 열전도도는 약 22W/cm.K로 열전도도가 가장 큰 물질로 알려져 있으며, 비저항은 10$\Omega$.cm 이상의 높은 값을 갖는다. 대부분 열전도도가 큰 것으로 알려진 물질들은 Cu, Ag 등과 같이 전자의 흐름에 의하여 열이 전도되기 때문에 큰 전기전도도를 함께 갖는 것일 일반적이다, 그러나, 다이아몬드는 빠른 phonon의 이동에 의하여 열전도가 이루어지므로 전기적으로 절연 특성을 갖으면서도 큰 열전도가 가능하다. 단결정 다이아몬드는 고방열 절연체로서 이상적인 물질 특성을 보여준다. 전기절연성을 갖는 열전도층으로 다이아몬드를 이용하기 위해서는 저가로 제조가 용이한 화학기상증착법을 이용하여야 한다. 화학기상증착법으로 제조된 다결정 다이아몬드 박막의 열전도도는 약 21W/cm.K로 여전히 매우 높은 값을 갖는 것으로 알려져 있지만, 비저항 값은 인위적으로 도핑을 전혀 하지 않은 상태에서도 106$\Omega$.cm 정도의 낮은 값을 갖는다. 전혀 도핑을 하지 않았음에도 전도성을 갖는 특이한 특성을 다결정 다이아몬드가 보여 주고 있으므로 이에 대한 연구는 주로 전기 전도성을 갖는 특이한 특성을 다결정 다이아몬드가 보여주고 있으므로 이에 대한 연구는 주로 전기전도성의 원인을 규명하는데 집중되고 있다. 아직 명확한 전도 기구는 제안되고 있지 못하지만 전도성의 원인은 수소와 관련이 있고 전도는 표면을 통하여 이루어진다는 것이다. 산(acid)을 이용하여 다결정 다이아몬드 박막을 세척하면 전기 전도성이 사라지고 높은 저항값을 갖는 박막을 얻게 되는데 박막을 세척하는 공정은 박막의 표면만을 변호시키므로 표면에 있던 전기전도층이 용액 처리를 통하여 제거되므로 전도성이 사라진다고 생각하는 것이다. 그러나, 본 연구에서는 두께가 두꺼울수록 저항값이 증가하는 것이 관찰되었고 기존의 측정방식인 수평적인 저항 측정법에 대하여 수직적 방향으로 저항을 측정하면 저항값이 1/2 정도 작게 측정되었다. 다결정 다이아몬드에서 표면을 통하여 전류가 흐른다면 박막의 두께에 따른 변화가 나타나지 않아야 하고 수직적인 전류 측정법이 오히려 더 큰 저항을 보여주어야 한다. 기존의 표면 전도 모델로는 설명되지 못하는 현상들이 관찰되었고 정확한 전기 전도 경로를 확인하기 위하여 전해 도금법으로 금속들이 석출되는 모습을 관찰하였다. 이 방법을 통하여 다결정 다이아몬드에서 전류는 결정입계를 통하여 전도됨을 알 수 있었다. 온도에 따른 다결정 다이아몬드의 전기전도도 변화를 관찰하였고 이로부터 활성화 에너지 값을 구할 수 있었다. 다결정 다이아몬드의 전도도는 온도에 따라서 0.049eV와 0.979eV의 두 개의 활성화 에너지를 갖는 구간으로 나뉘어졌다. 이로부터 다결정 다이아몬드에는 활성화 에너지 값이 다른 두 종류의 defect level이 형성되는 것으로 추정할 수 있고 이 낮은 defect level에 의하여 전도성을 갖는 것으로 생각된다.

• Journal of Science Education
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• v.34 no.2
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• pp.237-245
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• 2010

The purpose of this study was to analyze hierarchy for high school students' concepts about genetics. The assessment of genetics related concept was conducted for 10th and 11th grade students and a hierarchy map was schematized based on the evaluation result using Knowledge State Analysis Method. Some differences were found when comparing the result of whole students' hierarchy with hierarchy on 7th national science education curriculum. In analyzing hierarchy by grade, concepts of highest and lowest level turned out same but some concepts of middle level changed. In case of analysis of hierarchy for concepts about genetics by score, as score was higher, the number of concept in lower level became larger and the relationship among concepts became more structurized. Following studies are required to develop specific teaching strategies for having effective genetics concept and conduct case study of applying the concept hierarchy through this method to class in the field.

• Journal of Digital Convergence
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• v.18 no.4
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• pp.315-323
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• 2020

This study is a similar experimental study before and after non-equivalence control to examine the effect of fundamental nursing practice education applying reciprocal peer tutoring on confidence in performance, core nursing skills, and practice satisfaction of nursing students. Data collected by 83 people sophomore P university nursing students, the study period is from May 17 to 11 March 2019. As a results, the fundamental nursing practice education applied with the reciprocal peer tutoring method had an effect on the confidence in performance and core nursing skills of 'medium' degree of difficulty, and had a positive effect on the satisfaction of practice. In the future, this study suggests that the method of reciprocal peer teaching is extended to various practical majors and the effects of core nursing skills are tested.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.784-791
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• 2018

UiO-66 particles were synthesized under various synthesis conditions to study the adsorption of carbon dioxide for hydrogen purification. For the purpose, the design and analysis of experiments was performed using statistical design of experiment method. As the synthesis time, temperature and acetic acid amount increased, the crystallinity of UiO-66 particles increased. Especially, the amount of acetic acid was confirmed as an important factor in determining the crystallinity of the particles. The specific surface area of the particles measured by the nitrogen adsorption method also showed a similar tendency. Using the general factor analysis in the experimental design method, the main effects and interactions of major factors were analyzed. In addition, the carbon dioxide adsorption capacity was predicted using a nonlinear regression method. Then, the adsorption performance was shown through surface and contour maps for all ranges.

• Food Science of Animal Resources
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• v.33 no.5
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• pp.610-616
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• 2013

Loop-mediated isothermal amplification (LAMP) is an emerging detection technology for the amplification of DNA under isothermal conditions. The aim of this study was to develop a rapid and reliable LAMP technique for the detection of Cronobacter sakazakii in milk powder. In order to enhance the sensitivity and specificity, LAMP primers targeting outer membrane protein A (ompA) gene of C. sakazakii were designed using Explorer V4 software. Thirty seven C. sakazakii strains and 13 pathogenic microorganisms were used for comparative detection of C. sakazakii using polymerase chain reaction (PCR), real-time PCR, and LAMP. LAMP developed in this study could specifically detect C. sakazakii strains without cross-reactivity with other foodborne pathogens. LAMP products amplified from ompA gene of C. sakazakii were digested with with HhaI and NruI enzyme. The specificity of LAMP was confirmed by restriction fragment length polymorphism (RFLP) analysis. LAMP could detect C. sakazakii within 1 h without bacterial culture and its detection limit was as low as 1 CFU/mL C. sakazakii in milk. In the comparison of the sensitivity, LAMP showed 10,000- and 100-times higher detection limit than PCR or real-time PCR, respectively. Therefore, this study can conclude that LAMP is a rapid and reliable detection technique for C. sakazakii contaminated in powdered milk.

• Journal of the Korean Society for Library and Information Science
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• v.57 no.3
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• pp.231-248
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• 2023

The purpose of this study is to trigger a discussion on the educational gap between regions in school library resources. To this end, differences and correlations between other resources invested in the school library and output results were analyzed according to manpower allocation. There was a positive correlation between the number of books, the budget, the number of seats, the number of borrowed materials, and the number of students. It was analyzed that manpower allocation had a negative correlation with the number of subjects in which the ratio of students, the lowest grade in the achievement evaluation, was more than 1/2. As a result of examining the staffing according to the 「School Library Promotion Act」 by regional characteristics, it was found that the allocation rate was statistically significantly higher in the order of metropolitan area, and provincial unit. Depending on the regional characteristics, there were differences in net asset per household as well as differences in school library manpower assignment rates. In contrast, the large cities with relatively affluent school library manpower assignment rates were found to be higher. Therefore, based on the survey contents of this study, it was emphasized that the manpower stipulated in the 「School Library Promotion Act」 should be deployed as soon as possible even in relatively poor areas to bridge the educational gap between regions.

• Polymer(Korea)
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• v.29 no.6
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• pp.599-604
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• 2005

The hyaluronic acid (HA) with excellent biocompatibility has been combined with lactide, the ester dimer of polylactide, with good biodegradability to produce biocompatible materials which can control the period of degradation in a human body. By freeze frying method, HA and lactide were crosslinked with crosslinking agent, 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC). Degree of lactide and EDC reaction was determined by the analysis of nuclear magnetic resonance spectroscopy. Both lactyl group and EDC conversion increased as the mole ratio of lactide to HA increased from 5 to 13. The membrane swelled less and became more brittle with the more addition of lactyl group resulting from the higher mole ratio of lactide to HA. Swelling ratio decreased and tensile modulus increased due to the more addition of lactyl group as the EDC concentration increased or reaction temperature decreased. Drug release experiment from various membranes with different degree of crosslinking showed that permeability decreased with increasing degree of crosslinking. The degradation became slower with the more addition of lactyl group. Mechanical property and degradation rate of the synthesized membrane were shown to be controlled through adjusting operation parameters such as mole ratio, temperature, and crosslinking agent concentration.

• Journal of Digital Contents Society
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• v.11 no.2
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• pp.129-134
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• 2010

Today's elementary schools emphasize practice- and learner-based computer courses. In this research, we found solutions to the above issues by adapting a demonstration/practice teaching method led by multiple teaching assistants, expanding lessons tailored to each student's own level. We chose fourth graders from three classes at Elementary School as the subject for this research. Through this research, we have analyzed the students' study results, self-efficacy, response and interest in the computer courses by examining three groups of students: the first group led by a teacher's demonstration and practice, the second group by a teaching assistant's demonstration and practice, and the last by multiple teaching assistants' demonstration and practice. As a result, we were able to show that a computer course taught by multiple teaching assistants will help not only induce an interest and motive for a mutual learning environment among the students, but also bring positive effects on the study results and self-efficacy.

• Asia Marketing Journal
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• v.6 no.3
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• pp.27-57
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• 2004

Studies on brand loyalty have been classified into two approaches; the behavioral approach and the attitudinal approach. The main topics of both approaches have been customers' loyal or nonloyal attitude toward brands and the rate of repurchase generating process. However, previous research has overlooked dynamic and in-depth aspects of brand loyalty. With a qualitative research perspective, the present study adds insight to the current research on brand loyalty, concerning the disregarded aspects of brand, based on phenomenological interviews. On the foundation of consumer-brand relationship types suggested by Fournier(1998), this study examines various kinds of relationship types between Korean consumers and their preferred beer brands. Findings show different aspects and dynamic essence of brand loyalty through the analysis of these relationships. Moreover, a variety of sources of brand loyalty were identified. It was concluded that "actual" brand loyalty and "apparent" brand loyalty may not coincide at all times. In addition, consumers' life events and life themes were identified as important determinants of brand loyalty.

• Journal of the Korean Data and Information Science Society
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• v.21 no.1
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• pp.51-59
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• 2010

In the case that the regression function has a discontinuity point in generalized linear model, Huh (2009) estimated the location and jump size using the log-likelihood weighted the one-sided kernel function. In this paper, we consider estimation of the unknown number of the discontinuity points in the regression function. The proposed algorithm is based on testing of the existence of a discontinuity point coming from the asymptotic distribution of the estimated jump size described in Huh (2009). The finite sample performance is illustrated by simulated example.