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A study on the growth and characteristics of $AgGaS_2$ single crystal thin film by hot wall epitaxy (HWE 방법에 의한 $AgGaS_2$단결정 박막성장과 특성에 관한 연구)

  • 홍광준;정준우
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.8 no.2
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    • pp.211-220
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    • 1998
  • The stochiometric composition of $AgGaS_2$polycrystal source materials for the single crystal thin films were prepared from horizontal furnace. From the extrapolation method of X-ray diffraction patterns, it was found that the polycrystal $AgGaS_2$has tetragonal structure of which lattice constant $a_0\;and \;c_0$ were 5.756 $\AA$ and 10.305 $\AA$, respectively. $AgGaS_2$single crystal thin film was deposited on throughly etched GaAs(100) substrate from mixed crystal $AgGaS_2$by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $590^{\circ}C$ and $440^{\circ}C$ respectively, and the growth rate of the single crystal thin films was about 0.5 $mu \textrm{m}$/h. The crystallinity of the grown single crystal thin films was investigated by the DCRC (double crystal X-ray diffraction rocking curve). The optical energy gaps were found to be 2.61 eV for $AgGaS_2$single crystal thin films at room temperature. The temperature dependence of the photocurrent peak energy is well explained by the Varshni equation, then the constants in the Varshni equation are given by${\Alpha};=;8.695{\times}10^{-4};eV/K,and;{\beta};=;332;K$. from the photocurrent spectra by illumination of polarized light of the $AgGaS_2$single crystal thin film, we have found that crystal field splitting $\Delta$Cr was 0.28 eV at 20 K. From the PL spectra at 20 K, the peaks corresponding to free and bound excitons and a broad emission band due to D-A pairs are identified. The binding energy of the free excitons are determined to be 0.2676 eV and 0.2430 eV and the dissociation energy of the bound excitons to be 0.4695 eV.

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Constructing a Green Network and Wind Corridor to Alleviate the Urban Heat-Island (도시열섬현상 완화를 위한 녹지네트워크 및 바람길 구축)

  • Cha, Jae-Gyu;Jung, Eung-Ho;Ryu, Ji-Won;Kim, Dae-Wuk
    • Journal of the Korean Association of Geographic Information Studies
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    • v.10 no.1
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    • pp.102-112
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    • 2007
  • Like other organic beings, modern cities change every day. Unlike in the past, changes of space which have been taking place in concentrated spaces during short periods of time have worsened the environment of cities creating environmental problems. In particular, the urban heat-island phenomenon, which is caused by changes in using the earth's surface, has emerged as a key social issue along with health problems and economic difficulties. The Green Network has been introduced as an urban planning approach to solve the urban heat-island phenomenon. This study suggests constructing a Green Network through analyzing the urban heat island phenomenon, land cover classification, and linkage possibility with the Green Network and wind corridors by researching Jung-Gu, and Nam-Gu in Daegu Metropolitan City. In conclusion, this study presented the construction of a broad and detailed Green Network of object areas by assigning Apsan to the southern area and mountain area as the core, two areas of Nam-Gu and six areas of Jung-Gu such as Duryu Park and, Dalsung Park as footholds and other school land and park facility areas as footholds-to-be areas. In particular, Camp Walker, which is connected with Apsan, is not only a foothold but connected to the core, is necessary to preserve after being transferred from the U.S. Army. In addition, assigning the Susung Bridge area of Jung-Gu and the Camp Walker area of Nam-Gu as the wind corridor areas is recommended.

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A comparative study on creativity according to major of college students: focusing on pre-service early childhood teachers, pre-designers and pre-engineers (대학생의 전공에 따른 창의성 비교 연구 : 예비유아교사, 예비디자이너, 예비공학자를 중심으로)

  • Kim, Hyoung Jai;Lee, Jun Yeon;Eom, Se Jin
    • Journal of Digital Convergence
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    • v.15 no.6
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    • pp.19-27
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    • 2017
  • The purpose of this study was to analyze the differences of creativity according to major of college students focusing on pre-service early childhood teachers, pre-designers and pre-engineers. The subjects were 132 four grade of university students attending K and T university in Busan, Korea. Data were analyzed with one-way MANOVA to find out the differences of creativity according to their major. Results of this study as follows: first, overall creativity was significantly higher in preliminary designers than pre-service early childhood teachers and pre-engineers. Second, the fluency of pre-service early childhood teachers and pre-designers was significantly higher than that of pre-service engineers. The abstraction was significantly higher in pre-service early childhood teachers than pre-engineers. The elaboration of pre-designers was significantly higher than that of pre-service teachers and pre-engineers. Openness was significantly higher in pre-designers than pre-engineers, and pre-engineers were significantly higher than pre-service early childhood teachers. Therefore, this study suggests that the major in creativity curriculum and program development for college students should be considered, and the results of this study will be used as basic data of the creativity education program.

Development of Science Education through Academic Journal of Educational Associations during the Modern Educational Period (1876${\sim}$ 1910) in Korea (근대 교육기(1876 ${\sim}$ 1910) 학회지를 통한 과학교육의 전개)

  • Lee, Myon-U
    • Journal of the Korean earth science society
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    • v.22 no.2
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    • pp.75-88
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    • 2001
  • From 1905 to 1910 when the deepening national and educational crisis existed, the Korean intellectuals established many educational associations and published many academic journals. In this study, the researcher investigated 9 academic journals which had 132 books published by these educational associations in Korea during the Modern Educational Period (1876${\sim}$1910). The results of this study were summarized as follows : (1) The contents of journals mainly consisted of the Korean history and geography for the purpose of increasing Korean people's identification. And also the journal articles dealt with the western political and economic systems. In addition to these contents, the journals included many scientific studies which were aimed at educating the ordinary Korean people. (2) The scientific articles from these journals were mainly composed of earth science and biology including physiology, while the number of articles for physics and chemistry was less. (3) These scientific articles were published by the same writer in a series .However, the academic level of these was like a school textbook. Based on the results of the data analysis, it is believed that these journal articles possibly were used as a school textbook for science education.

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Groping for Cooperative Space Activities in the Northeast Asia (동북아시아에서의 우주협력의 모색)

  • Rhee, Sang-Myon
    • The Korean Journal of Air & Space Law and Policy
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    • v.22 no.1
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    • pp.75-103
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    • 2007
  • The purpose of this paper is to suggest to tackle the problem of poor cooperation in space activities, by re-examining the nature of the competitive political environment, and by building up a normative overarching framework, One of the most acute problems that hampers regional cooperation is the U.S. influence as represented in the MTCR, a supplier's cartel, as was evidenced in the ill-fate of the 2001 launch contract between China and Korea the next year. Notably China, the third space power in the world, has not been allowed to join the MTCR despite her application in June 2004. A possible reconciliation between China and the MTCR over her application for a partnership would set a cornerstone in building up a cooperative environment in the Northeast Asia. Just as the Helsinki process was an overarching norm building framework, comprising human rights, security and environmental issues, it would be desirable that a future peace framework in Northeast Asia dealing with the pending issues of Korean peninsula should also comprise of such broad issues as one relating to cooperation in space activities in the region. South Korea could tap expertise from her neighbor China. When South Korea become an independent space power either with her own technology or otherwise, she would be in a better position to play a role as a balancer in coordinating between the two neighboring space giants. It is remarkable that the Japanese led APRSAT has contributed much in establishing Sentinel Asia as a part of the Disaster Management Scheme, in that each participant, whether it be a state agency, or a private entity like a university or a research institute, can tap the common data to contribute to the common good of safety.

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The Effects of Mentoring Network of Single Mothers with Dependent Children on Mentoring Function and Empowerment (한부모 여성의 멘토링 연결망 특성이 멘토링 기능 및 임파워먼트에 미치는 효과 연구)

  • Lee, In-Sook
    • Korean Journal of Social Welfare
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    • v.61 no.4
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    • pp.61-84
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    • 2009
  • This study is to analyze the nature of mentoring network of single mothers with dependent children and to show the mentoring network effect on mentoring function and empowerment applying social network approach. 439 single mothers with dependent children in Busan and Gyeongsangnam-do have been surveyed about mentoring network properties. The results are 1. The mentoring relationships between single mothers have been shown in various size and relationship characters. The out-degree of Their network is low, the range is narrow, and the tie-strength is weak. 2. When the effect of mentoring network characteristics on mentoring function has been analyzed, in career functions, the range of network and the strength of relationships are represented as significant variables among the mentoring network characteristics, in psychosocial functions, the size of network and the strength of relationships are shown as significant variables, and the inverted-U-shaped relationship according to the size of network has not been revealed. In role modeling function only the size of network is represented as a significant variable. 3. The direct effect of mentoring network of single mothers with dependent children has not been much on empowerment and the career related function among mentoring functions has been revealed as the variable, which affect on empowerment. Based on these results the suggestions and implementations are mentioned in this paper.

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An Experimental Study on the Construction Performances and Economical Evaluation of the Self-compacting Concrete by Cementitious Materials (결합재에 따른 자기충전 콘크리트의 시공성 및 경제성 평가에 관한 실험적 연구)

  • Kwon, Yeong-Ho
    • Journal of the Korea Concrete Institute
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    • v.29 no.3
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    • pp.315-322
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    • 2017
  • The purpose of this study is to investigate experimentally the construction performances and economical evaluation of the self-compacting concrete in actual site work after selecting the optimum mix proportions according to cementitious materials. Slag cement type of 46.5% slag powder and belite cement of 51.4% $C_2S$ content, lime stone powder as binders are selected for site experiment including water cement ratio. Also, test items for optimum mix proportion are as followings ; (1) Slump flow, 500 mm reaching time, V-type flowing time and U-box height (2) Setting time, bleeding, shortening depth and adiabatic temperature rising (3) Mixing time in plant (4) Concrete quantity and cost, quality control in actual concrete work. As test results, (4) Optimum water-cement ratio ; Slag cement type 41.0% and belite cement 51.0% (2) Setting time and bleeding finishing time of slag cement are faster, bleeding content of slag cement is higher, shortening depth and adiabatic temperature rising of belite cement type are lower (3) Optimum mixing time in batcher plant is 75 seconds and concrete productive capacity is about $100{\sim}110m^3/hr$. (4) Belite cement type is lower than slag cement type in material cost 14.0%, and concrete quantity in actual concreting work save 3.3% in case of belite cement type. Therefore, self-compacting concrete of belite cement type is definitely superior to that of slag cement type in various test items without compressive strength development.

Fractionation of Exopeptidase from Viscera of Argentina Shortfin Squid, Illex argentinus (원양산 오징어(Illex argentinus) 내장으로부터 Exopeptidase의 분획)

  • Kim, Hye-Suk;Kim, Jin-Soo;Heu, Min-Soo
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.37 no.8
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    • pp.1009-1017
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    • 2008
  • For the effective use of exopeptidase from squid viscera as food processing aids, the viscera of Argentina shortfin squid (Illex argentinus) were fractionated by various methods such as acetone treatment, ammonium sulfate treatment, anion exchange chromatography, and gel filtration. The positive exopeptidase fractions were obtained from the fraction II treated by cold acetone ($30{\sim}40%$, w/w), the fraction V by ammonium sulfate ($60{\sim}70%$ saturation), the fraction II (0.2 M NaCl) by anion exchange chromatography, and the fraction I ($30{\sim}50\;kDa$) by gel filtration. The specific activities of positive fractions from viscera of I llex argentinus against substrates were higher to LeuPNA than to ArgPNA. Total activity and recovery against LeuPNA of positive fraction by gel filtration were 1,867 U and 30.69%, respectively, which were the highest among those of positive fraction. The results suggested that the gel filtration chromatography method was the most efficient method for the fractionation of exopeptidase from viscera of Illex argentinus.

A Comparison of Characteristics between Danish and Korean Farmhouses -In Reference to Farmhouse Plans, Use of Rooms including Furniture Arrangement, and Building Materials-

  • Choi, Jung-Shin
    • International Journal of Human Ecology
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    • v.8 no.1
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    • pp.67-78
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    • 2007
  • The aim of this paper was to compare differences and similarities of farmhouses between Denmark and Korea as a cross-cultural study. Farmhouses built during the 18th and 19th centuries in Denmark, and ones from Chosun Dynasty (AD. 1392-1910) in Korea were targets of this study. Literature study and field trips to districts and open-air museums in both countries were used. Field trips were carried out during summer of 2005 in Denmark, and fall of 2005 in Korea. Detailed comparisons focused on farmhouse plans, the use of rooms and furnishing, and building materials. As a conclusion, some differences were found between the two countries. In terms of farmhouse plans, square types with four wings, and parallel types were the most frequent forms in Denmark, while a few types, such as the "I", "L", "U" shapes and square types, were more frequently found in Korea. In Denmark, the most important room was the dwelling-room, in which daily family life took place. Every member of the family slept, ate, and worked here, and kept geese and young animals during the winter season. Therefore, this room was laid out in the center of the house. However, Anbang, the most important room in Korea, was not situated in the best part of the house. Instead, the Daechung-maru occupied the center and the best place because the daechung-maru, in which the ancestral ceremony was held, was thought of as more important than a place for live people. Also the use of rooms and furnishing was quite different between the two countries, reflecting each life style. Danish furnishings represented practical daily life, while Korean furnishings reflected more conceptual aspects. It might have resulted from Confucianism in the Chosun Dynasty, which ruled daily life and even influenced use of rooms and furnishings. In other word, philosophy influenced common peoples' daily life and living environment. With reference to building materials, there was rarely a difference between the two countries. Major materials for farmhouse were quite common, such as half-timbering wood and clay, but the difference was in bricks and roof coverings. Bricks were rarely used in Korean farmhouses, while rice-straw was rare for the roof of a Danish farmhouse. Of course, the choice of materials was strongly affected by the local surroundings and overall environment. This result can give some clues for design ideas when architects and interior designers plan housing that is adapted for local peoples. This kind of cross-cultural study can also contribute to one's understanding of foreign culture, especially in housing and culture. And, it can broaden one's insight of design ideas for designers who have to compete frequently with designers in foreign countries.

The Comparative Study of Effect on Speech before and after Orthognathic Surgery of Patients (악교정 환자의 악교정 수술전후 발음양상에 대한 비교연구)

  • Kwon, Kyung-Hwan;Kim, Soo-Nam;Lee, Dong-Keun;Cho, Yong-Min;Lee, Suk-Hyang
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.22 no.2
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    • pp.191-205
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    • 2000
  • The purpose of this study was undertaken to determine the effects of orthognathic surgery on speech. The hyposis stated herein is that functional behaviors of the dentofacial complex, such as speech production, may be adversely affected by deviations of a structural nature(especially, Class III malocclusion). Twenty adults with Class III malocclusion(13 female and 7 male) were studied preoperative, immediate postoperative and either 6 or 12 months postoperative lateral cephalograms. They had mandibular prognathism and had undergone mandible setback operation. The position of tongue, soft palate(Uvula), hyoid bone, respiratory track width, and pharyngeal depth were assessed on lateral cephalograms with 23 cephalometric variables, ANOVA, Paired t-tests and Pearson's product-moment correlation coefficient tests were used to evalute the operative changes in all cephalometric parameters. A experienced speech and language pathologists performed narrow phonetic transcriptions of tape-recorded words and sentences produced by each of the ninth patients and the recording tapes were analyzed by phonetic computer program(Computerized Speech Lab(CSL) Model 4300BI(U.S.A.)) These judges also recorded their ratings of each patient's overall consonants, hypernasality, hyponasality, and articulation proficiency. The results obtained are as follows; 1. There were significant changes in distance of posterior pharyngeal wall to tongue (TI-TW2, TS-TW3) after the surgery at 6 months postoperatively(each p<0.01 p<0.05). 2. The posterior tongue point(TI, TS, PPT) moved posteriorly after surgery and remained to its changed position at 6 months postoperatively(p<0.05). The displacement of tongue was correlated with the movement of mandibular setback amount(p<0.05). The hyoid bone moved posteriorly superiorly after immediate postoperative period. There was significant changes in hyoid bone movement after immediated postoperative period(p<0.05), but returned to its original position during the follow-up period(p>0.05) 3. The soft palate was displaced posteriorly superiorly after immediated operative period and remained to its changed position at 6 months postoperatively(p<0.05). ANS-PNS-SPT angle increasing, PPU-PPPo distance narrowing was showed after surgery, and remained its appearance 6 months postoperatively(p<0.05). 4. There were significant changes in formant value and squre diagram of vowel sound after the orthognathic surgery and the follow-up period. There were significant changes in /ㅅ/sound and posterior tongue sound. 5. The posterior movement of tongue and the posteriosuperior movement of soft palate was correlated with mandibular setback amount after orthognathic surgery. On the vowel squre diagram, the author found that the place of articulation after operation moved downward, backward, upward. 6. In assessing speech abnormalities, dental occlusion should be considered as a contributing factor. The vast majority of subjects with preoperative misarticulations eliminated or reduced their errors following orthognathic surgery. There was significant difference in speech impovement between pre- and postoperation.

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