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Elementary Schooler's Recognition and Understanding of the Scientific Units in Daily Life (초등학교 학생들의 생활 속 과학단위 인식과 이해)

  • Kim, Sung-Kyu
    • Journal of Science Education
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    • v.36 no.2
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    • pp.235-250
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    • 2012
  • This paper aims to find out whether or not elementary school students recognize and understand scientific units that they encounter in their everyday life. To select appropriate units for the survey, first, scientific units in elementary textbooks of science and other science related subjects were analyzed. Then it was examined how these units were related to the learners' daily life. The participants in the current survey were 320 elementary school 6th graders. A questionnaire consisted of 11 units of science, such as kg for mass, km for distance, L for volume, V for voltage, s for time, $^{\circ}C$ for temperature, km/h for speed, kcal for heat, % for percentage, W for electric power, pH for acidity, which can often be seen and used in daily life. The students were asked to do the following four tasks, (1) to see presented pictures and select appropriate scientific units, (2) to write reasons for choosing the units, (3) to answer what the units are used for, and (4) to check where to find the units. The data were analyzed in terms of the percentage of the students who seemed to well recognize and understand the units, using SPSS 17.0 statistical program. The results are as follows: Regarding the general use of the units, it was revealed that almost the same units were repeated in science and other subject textbooks from the same grade. With an increase of the students' grade more difficult units were used. As for the use of each unit, it was found that they seemed to relatively well understand what these units kg, km, L, $^{\circ}C$, kcal, km/h, and W stand for, showing more than 91% right. However, the units of V, s, in particular, %, and pH did not seem to be understood. With respect to the recognition of the units, most students did not recognize such units as L for volume and pH for acidity, probably because the units are difficult at the elementary level in comparison to other scientific units. The students indicated that schools were the best place where they could learn and find scientific units related to life, followed by shops/marts, newspapers/broadcasting, streets/roads, homes, and others in that order. The results show that scientific unit learning should be conducted in a systematic way at school and that teachers can play a major role in improving students' understanding and use of the units.

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Research Trends in Science Gifted Education from 2011 to 2015: Literature Analysis vs Social Network Analysis (2010년부터 2015년까지 국내 과학영재교육의 연구동향 분석 : 문헌분석 대 사회네트워크분석)

  • Yoon, Jin A;Seo, Hae-Ae
    • Journal of Science Education
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    • v.40 no.3
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    • pp.267-286
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    • 2016
  • The study aimed to investigate a research trend in science gifted education of six years from 2010 to 2015 by utilizing literature analysis and Social Network Analysis (SNA) methods. In this study, 275 papers published in eight major academic journals of science education and gifted education were selected as research subjects. First, through the literature analysis, it was found that the most frequent research topics were cognitive characteristics (25.8%), curriculum/programs (22.6%), and social and emotional characteristics (20.2%). For the research method employed in research papers, the survey research (46.5%) was appeared as the most frequently employed method, and followed by experimental (18.8%), program development (10.6%), correlation (10.3%), and qualitative (6.4%) research methods. The most frequent research subject was appeared as middle school students (33.7%) and followed by elementary school (30.6%), and high school (12.7%) students. Second, the SNA method was utilized for producing keyword frequency, degree centrality and network analyses. It was appeared that the most common keywords over six years included 'science gifted', 'gifted education', and 'creativity' and frequent keywords were science gifted, gifted education, gifted, creativity, science inquiry, perception, (creative) problem solving, science high school, scientific attitude, and STEAM. Third, through 2-mode network analysis, it was found that the research papers about cognitive characteristics were mainly related to perceptions, thinking ability, scientific argumentation, science inquiry and so on. It was also found that the research papers about social and emotional characteristics were related to correlation, motivation, creativity-character, self-efficiency and so on. It was concluded that the SNA method can be performed with literature analysis together for better understandings and interpretations of the research trend of science gifted education in-depth.

Displayed Subjects of Practice and Case-Mix of Private Practitioners in Taegu City (개원의의 진료과목표방 및 진료환자 구성)

  • Park, Jae-Yong;Oh, Kang-Jin;Kam, Sin
    • Health Policy and Management
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    • v.2 no.1
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    • pp.42-65
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    • 1992
  • To survey the specialties or sujects of practice displayed by the private practitioners the authors visited 691 clinics in Taegu from April 1 to May 18, 1991, At the same time, a mail questionnaire was administered to ask the number of displayed subjects of practice, and the reasons for displaying the subjects, reasons for not displaying in case of no specialty was displayed, composition of patients, and role as a specialist. The questionnaire was returned by 308(44.6%) practitioners. The distributions of private practitioners by specialty were 13.9% for internal medicine (IM), 11.7% for pediatrics(Ped), 13.0% for obstetrics '||'&'||' gynecology(OBGY), 11.1% for general surgery(GS), 10.0% for family practice(FP), and 5.3% for general practitioner(GP). Ninety percent of the specialists have displayed their specialty in their offices. Among all the private practitioners, 61.9% of them have displayed their subjects of practice and 23.7% have shown telephone number. Among private practitioners who displayed the subjects of practice, 80.6% have signs of 'subjects of practice'. Mean number of the displayed subjects of practice for the all private practitioners is 1.20, and 1.93 for the private practitioners who displayed subjects of practice. FP and GS have displayed their subjects of practice in 91.2% and 87.0% respectively and OBGY have displayed in 32.2%, the lowest percentage among all the soecuaktues. IM specialists displays pediatrics as a major subject of practice in 72.1% the pediatricians display IM in 88.9% the OBGYs display pediatrics in 77.8%, and the GSs display IM in 51.9%. Most commonly displayed subjects of practice are Ped and IM. Sixty-five percent of the private practitioners answered that they don't display their specialties because their clinics are "primary health care facility". The reasons for displaying the subjects of practice and its relevance with their own specialty(45.6%), and the difficulty in clinic management only with the patients for their own specialty(36.9%). The proportion of clinics whose patients of other specialty are than their own specialty accounted less than 10% was 52.8% and that accounted more than 51% was 16.0%. Specially, 51.4% of GS specialists cared more than 51% of patients of other specialty area than their own specialty. Most of the patients of IM, Ped, and OBGY specialists are the patients of their own specialty. However, 56.8% of GS care more of IM patients and only 24.3% of them care mostly GS patients, The respondents to the mail questionnaire who stated that they can not play the role of specialist well are 30.5% and especially 72.9% of the GS specialists state so. The proportion of respondents who do not suffort the private practice of specialists is 71.1%. Among the surgical specialists, 82.7% of them rarely perform operation. The reasons for not performing operation are insufficient insurance fee (76.9%), and risk of operation(58.0%), so as the OBGY specialists. Above finidngs suggest that most of the specialists, especially surgeons, in the private practice can not play their role as a specialist. It is necessary to develop a policy that facilitates the production of practice and the retention of the specialists in the hospitals.s.

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Comparisons of Popularity- and Expert-Based News Recommendations: Similarities and Importance (인기도 기반의 온라인 추천 뉴스 기사와 전문 편집인 기반의 지면 뉴스 기사의 유사성과 중요도 비교)

  • Suh, Kil-Soo;Lee, Seongwon;Suh, Eung-Kyo;Kang, Hyebin;Lee, Seungwon;Lee, Un-Kon
    • Asia pacific journal of information systems
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    • v.24 no.2
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    • pp.191-210
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    • 2014
  • As mobile devices that can be connected to the Internet have spread and networking has become possible whenever/wherever, the Internet has become central in the dissemination and consumption of news. Accordingly, the ways news is gathered, disseminated, and consumed have changed greatly. In the traditional news media such as magazines and newspapers, expert editors determined what events were worthy of deploying their staffs or freelancers to cover and what stories from newswires or other sources would be printed. Furthermore, they determined how these stories would be displayed in their publications in terms of page placement, space allocation, type sizes, photographs, and other graphic elements. In turn, readers-news consumers-judged the importance of news not only by its subject and content, but also through subsidiary information such as its location and how it was displayed. Their judgments reflected their acceptance of an assumption that these expert editors had the knowledge and ability not only to serve as gatekeepers in determining what news was valuable and important but also how to rank its value and importance. As such, news assembled, dispensed, and consumed in this manner can be said to be expert-based recommended news. However, in the era of Internet news, the role of expert editors as gatekeepers has been greatly diminished. Many Internet news sites offer a huge volume of news on diverse topics from many media companies, thereby eliminating in many cases the gatekeeper role of expert editors. One result has been to turn news users from passive receptacles into activists who search for news that reflects their interests or tastes. To solve the problem of an overload of information and enhance the efficiency of news users' searches, Internet news sites have introduced numerous recommendation techniques. Recommendations based on popularity constitute one of the most frequently used of these techniques. This popularity-based approach shows a list of those news items that have been read and shared by many people, based on users' behavior such as clicks, evaluations, and sharing. "most-viewed list," "most-replied list," and "real-time issue" found on news sites belong to this system. Given that collective intelligence serves as the premise of these popularity-based recommendations, popularity-based news recommendations would be considered highly important because stories that have been read and shared by many people are presumably more likely to be better than those preferred by only a few people. However, these recommendations may reflect a popularity bias because stories judged likely to be more popular have been placed where they will be most noticeable. As a result, such stories are more likely to be continuously exposed and included in popularity-based recommended news lists. Popular news stories cannot be said to be necessarily those that are most important to readers. Given that many people use popularity-based recommended news and that the popularity-based recommendation approach greatly affects patterns of news use, a review of whether popularity-based news recommendations actually reflect important news can be said to be an indispensable procedure. Therefore, in this study, popularity-based news recommendations of an Internet news portal was compared with top placements of news in printed newspapers, and news users' judgments of which stories were personally and socially important were analyzed. The study was conducted in two stages. In the first stage, content analyses were used to compare the content of the popularity-based news recommendations of an Internet news site with those of the expert-based news recommendations of printed newspapers. Five days of news stories were collected. "most-viewed list" of the Naver portal site were used as the popularity-based recommendations; the expert-based recommendations were represented by the top pieces of news from five major daily newspapers-the Chosun Ilbo, the JoongAng Ilbo, the Dong-A Daily News, the Hankyoreh Shinmun, and the Kyunghyang Shinmun. In the second stage, along with the news stories collected in the first stage, some Internet news stories and some news stories from printed newspapers that the Internet and the newspapers did not have in common were randomly extracted and used in online questionnaire surveys that asked the importance of these selected news stories. According to our analysis, only 10.81% of the popularity-based news recommendations were similar in content with the expert-based news judgments. Therefore, the content of popularity-based news recommendations appears to be quite different from the content of expert-based recommendations. The differences in importance between these two groups of news stories were analyzed, and the results indicated that whereas the two groups did not differ significantly in their recommendations of stories of personal importance, the expert-based recommendations ranked higher in social importance. This study has importance for theory in its examination of popularity-based news recommendations from the two theoretical viewpoints of collective intelligence and popularity bias and by its use of both qualitative (content analysis) and quantitative methods (questionnaires). It also sheds light on the differences in the role of media channels that fulfill an agenda-setting function and Internet news sites that treat news from the viewpoint of markets.

The Application of Operations Research to Librarianship : Some Research Directions (운영연구(OR)의 도서관응용 -그 몇가지 잠재적응용분야에 대하여-)

  • Choi Sung Jin
    • Journal of the Korean Society for Library and Information Science
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    • v.4
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    • pp.43-71
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    • 1975
  • Operations research has developed rapidly since its origins in World War II. Practitioners of O. R. have contributed to almost every aspect of government and business. More recently, a number of operations researchers have turned their attention to library and information systems, and the author believes that significant research has resulted. It is the purpose of this essay to introduce the library audience to some of these accomplishments, to present some of the author's hypotheses on the subject of library management to which he belives O. R. has great potential, and to suggest some future research directions. Some problem areas in librianship where O. R. may play a part have been discussed and are summarized below. (1) Library location. It is usually necessary to make balance between accessibility and cost In location problems. Many mathematical methods are available for identifying the optimal locations once the balance between these two criteria has been decided. The major difficulties lie in relating cost to size and in taking future change into account when discriminating possible solutions. (2) Planning new facilities. Standard approaches to using mathematical models for simple investment decisions are well established. If the problem is one of choosing the most economical way of achieving a certain objective, one may compare th althenatives by using one of the discounted cash flow techniques. In other situations it may be necessary to use of cost-benefit approach. (3) Allocating library resources. In order to allocate the resources to best advantage the librarian needs to know how the effectiveness of the services he offers depends on the way he puts his resources. The O. R. approach to the problems is to construct a model representing effectiveness as a mathematical function of levels of different inputs(e.g., numbers of people in different jobs, acquisitions of different types, physical resources). (4) Long term planning. Resource allocation problems are generally concerned with up to one and a half years ahead. The longer term certainly offers both greater freedom of action and greater uncertainty. Thus it is difficult to generalize about long term planning problems. In other fields, however, O. R. has made a significant contribution to long range planning and it is likely to have one to make in librarianship as well. (5) Public relations. It is generally accepted that actual and potential users are too ignorant both of the range of library services provided and of how to make use of them. How should services be brought to the attention of potential users? The answer seems to lie in obtaining empirical evidence by controlled experiments in which a group of libraries participated. (6) Acquisition policy. In comparing alternative policies for acquisition of materials one needs to know the implications of each service which depends on the stock. Second is the relative importance to be ascribed to each service for each class of user. By reducing the level of the first, formal models will allow the librarian to concentrate his attention upon the value judgements which will be necessary for the second. (7) Loan policy. The approach to choosing between loan policies is much the same as the previous approach. (8) Manpower planning. For large library systems one should consider constructing models which will permit the skills necessary in the future with predictions of the skills that will be available, so as to allow informed decisions. (9) Management information system for libraries. A great deal of data can be available in libraries as a by-product of all recording activities. It is particularly tempting when procedures are computerized to make summary statistics available as a management information system. The values of information to particular decisions that may have to be taken future is best assessed in terms of a model of the relevant problem. (10) Management gaming. One of the most common uses of a management game is as a means of developing staff's to take decisions. The value of such exercises depends upon the validity of the computerized model. If the model were sufficiently simple to take the form of a mathematical equation, decision-makers would probably able to learn adequately from a graph. More complex situations require simulation models. (11) Diagnostics tools. Libraries are sufficiently complex systems that it would be useful to have available simple means of telling whether performance could be regarded as satisfactory which, if it could not, would also provide pointers to what was wrong. (12) Data banks. It would appear to be worth considering establishing a bank for certain types of data. It certain items on questionnaires were to take a standard form, a greater pool of data would de available for various analysis. (13) Effectiveness measures. The meaning of a library performance measure is not readily interpreted. Each measure must itself be assessed in relation to the corresponding measures for earlier periods of time and a standard measure that may be a corresponding measure in another library, the 'norm', the 'best practice', or user expectations.

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An Exploratory Study of business support policy by growth phases for Small and medium sized enterprises -Focused on Cheonan and Asan in ChungNam- (중소기업의 성장단계별 지원정책에 관한 탐색적 연구 -충청남도 천안·아산지역을 중심으로-)

  • Lee, Jae-Beom
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.5
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    • pp.2215-2224
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    • 2013
  • This study performed empirical analysis to estimate SMEs needs in terms of business support policy by growth stages(start-up growth expansion). The subject is the SMEs in Cheonan and Asan, ChungNam and the results are as follows. First, In the initial start-up stage, management plays a key role in dealing with money, labor force, markets and technology while running the organization is a key role of the management in the expansion stage. Major policies to help SMEs grow includes money provision needed in the start-up stage, domestic marketing assistance and the provision of human resources in the growth stage, and assistance in foreign marketing and R&D in the expansion stage. Second, To achieve markets businesses aim at entering the existing and niche markets in the initial phase, and creating new markets in the growth phase. Third, Labor force for technology, sales and management planning in the start-up stage, marketing in the growth stage, and labor force for production in the expansion stage are core man- power needed. Fourth, Money for technology development, securing land for factories, organizing man power, securing markets and running the company is needed in the initial and growth stages while fund for facility investment is needed to grow in the expansion stage. Five, Regarding technology, the initial stage needs technology related to new product development, renewing existing products, improving the existing manufacturing process or developing new manufacturing process, while the growth stage needs processing techniques, and the expansion stage needs technology for developing new manufacturing process. Sixth, Making supply contracts with conglomerates, SMEs and public institutions, and sales to foreign markets are ways for SMEs to grow sales. Seventh, What SMEs wish to get includes business incubating support, R&D assistance, information exchanges, practical use of the R&D results, merchandising support, help with the land to build factories and custom-made support for management in the foundation stage while the support they want to get in the growth stage and in the expansion stage is training assistance and trial production respectively.

A Study on Satisfaction level with Herbal Public Health Services and its Improvement Plans (한방공중보건서비스 만족도와 개선방안)

  • Lee, Jae-Won;Koo, Jin-Suk;Seo, Bu-Il
    • Korean Journal of Oriental Medicine
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    • v.18 no.2
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    • pp.65-89
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    • 2012
  • Objective : In order to investigate and improve public Korean medical health service satisfaction level, this study was designed. Method : A questionnaire has been conducted on 212 patients who received treatments at six public health centers in the northern part of Gyeongbuk during 15 days between Sep. 24 and Oct. 8, 2011. Result : 1. An Investigation on the usage of herbal clinics in public health centers reveals that 63.7% have received three times or more medical treatments previously and 61.8% have had their illness treated at other medical institutions. In regard to illness 32.1% have had arthritis or muscle aches. 50.9% have taken insurance medication after having had treatments at the public health centers. 66% have assessed acupuncture and moxa cautery the most satisfying. 2. To a question regarding whether herbal health treatment costs higher than that of physician's, the highest response at 31.6% is 'No'. And to a question regarding whether herbal medicines administered at public health centers have more side effects than that of physician's, the highest response at 39.6% is 'No'. 3. To a question regarding whether herbal treatment of public health centers has little effect against acute disease, 48.1% of responses are 'Fair'. To a question regarding whether herbal treatments, when compared with physician's treatments, boost better recovery of patients, 48.1% of responses are 'Fair'. To a question regarding whether herbal medicine is unscientific, when compared with that of western medicine, 38.2% of responses are 'Fair', To a question regarding whether herbal medicine has faster effect on disease than western medicine, 41.0% of responses are 'Fair'. To a question regarding whether herbal medicine is more effective on disease prevention and promotion of health than disease treatment, 38.2% of responses are 'Fair'. And to a question regarding whether the lack of various types of physical therapy devices in herbal medicine, when compared with western medicine causes inconvenience in herbal treatment, 42.0% of responses are 'Fair'. Those responses take up highest portion at each questionnaire. 4. A comparative study between herbal treatments and physician's treatments has also been conducted. To questions regarding which one of the two considering types of disease is the better, responses are the latter accounted for 43.9% against 'Cancer', the latter accounted for 45.3% against 'Endocrine disorders', the former accounted for 30.7% against 'Psychiatric disorders', the latter accounted for 38.2% gainst 'Otolaryngological(ENT) disease', the former accounted for 47.6% against 'Post traumatic stress disorder', and the former accounted for 52.4% against 'Muscle-skeletal disease'. 5. An investigation on frequency of patients' visits via (p<0.05) of subjects show a statistically significant difference. 6. First, an investigation on frequency of reasons of medical treatments reveal that age, occupation, monthly income, and insurance type (p<0.05) of subjects show a statistically significant difference. Secondly, an investigation on frequency of subjects taking insurance medicines after herbal health treatments reveal that monthly income (p<0.05) of subject shows a statistically significant difference. 7. First, an investigation on frequency of a claim that herbal treatments of public health center does not have great effect on acute disease reveals that age, education, and insurance type (p<0.05) of subjects show a statistically significant difference. Secondly, an investigation on frequency of analysis that herbal treatments has faster effect on disease compared with western treatments reveals that education level, religion, monthly income, and insurance type (p<0.05) of subjects show a statistically significant difference. 8. When herbal clinics of public health centers and general herbal medicine institutions are compared, a survey on additional treatments that herbal clinics need the most reveals that education level, monthly income, and insurance type (p<0.05) of subjects show a statistically significant difference. Secondly, an investigation on frequency of subjects who want various forms of herbal medicines reveals that occupation and insurance type (p<0.05) of subjects show a statistically significant difference. Conclusion : In order to improve efficiency of treatments and enhance patient's satisfaction level, this study suggests measures such as providing a differentiated acupuncture treatments as a whole, streamlining an reception procedure, adopting more elaborated computer system for a patient to get proper medical attention, standardizing a treatment duration in order for a maximum result, keeping regular office hours, and optimizing a consultation time for a patient.

A Study on the Research Trends in Library & Information Science in Korea using Topic Modeling (토픽모델링을 활용한 국내 문헌정보학 연구동향 분석)

  • Park, Ja-Hyun;Song, Min
    • Journal of the Korean Society for information Management
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    • v.30 no.1
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    • pp.7-32
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    • 2013
  • The goal of the present study is to identify the topic trend in the field of library and information science in Korea. To this end, we collected titles and s of the papers published in four major journals such as Journal of the Korean Society for information Management, Journal of the Korean Society for Library and Information Science, Journal of Korean Library and Information Science Society, and Journal of the Korean BIBLIA Society for library and Information Science during 1970 and 2012. After that, we applied the well-received topic modeling technique, Latent Dirichlet Allocation(LDA), to the collected data sets. The research findings of the study are as follows: 1) Comparison of the extracted topics by LDA with the subject headings of library and information science shows that there are several distinct sub-research domains strongly tied with the field. Those include library and society in the domain of "introduction to library and information science," professionalism, library and information policy in the domain of "library system," library evaluation in the domain of "library management," collection development and management, information service in the domain of "library service," services by library type, user training/information literacy, service evaluation, classification/cataloging/meta-data in the domain of "document organization," bibliometrics/digital libraries/user study/internet/expert system/information retrieval/information system in the domain of "information science," antique documents in the domain of "bibliography," books/publications in the domain of "publication," and archival study. The results indicate that among these sub-domains, information science and library services are two most focused domains. Second, we observe that there is the growing trend in the research topics such as service and evaluation by library type, internet, and meta-data, but the research topics such as book, classification, and cataloging reveal the declining trend. Third, analysis by journal show that in Journal of the Korean Society for information Management, information science related topics appear more frequently than library science related topics whereas library science related topics are more popular in the other three journals studied in this paper.

Studies on the Effect of Fiber Reinforcing upon Mechanical Properties of Concrete and Crack Mode of Reinforoed Concrete (섬유보강이 콘크리트의 역학적 특성과 철근콘크리트의 균열성상에 미치는 영향에 관한 연구)

  • 박승범
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.20 no.2
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    • pp.4645-4687
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    • 1978
  • This study was attempted to investigate the mechanical properties of concrete and crack control effects of reinforced concrete with steel and glass fiber. The experimental program includes tests on the properties of fresh concrete containing fibers, compressive strength, tensile strength, flexural strength, Young's modulus, Shrinkage and deformation of steel or glass fiber reinforced concrete. Also this study was carried out to investigate the effect of steel or glass fiber to retard the development in reinforced concrete subject to uniaxial tension and thus facilitate the use of steels of higher strength. The major conclusions that can be drawn from the studies are as follows: 1. The effect of the fibers in various mixes on fresh concrete confirmed that fibers do have a significant effect on the properties of fresh concrete, bringing much more stable and exhibiting a signiflcant reduction in surface bleeding, and that the cohesion is greatly improved and the internal resistance increases with fiber concentration. But the addition of an excess contents and length of fibers brings about the reduction of workability. 2. With the addition of steel fibers(1.5% Vol.) to concrete, the compressive strength as compared with plain concrete showed a very slight increase, but excess addition, over 1.5% Vol. of steel and glass fiber reduced its strength. 3. Splitting tensile strength of fiber reinforced concrete showed a significant increase tendency, as compared with plain concrete. In case of containing steel fiber (2.5%, 30mm), it showed that the maximum increase rate of 1.48 times as much rate, and in case of containing glass fiber (2.5%, 30mm), the increase rate of strength was 1.25 times as much rate. 4. Flexural strength of fiber reinforced concrete showed a significant tendency, as compared with plain concrete. Containing steel fiber (2.5%, 30mm) showed the maximum increase rate of 1.64 times as much rate and containing glass fiber (2.5%, 30mm) showed the increase rate of strength of 1.32 times as much rate, and in general, the 30mm length brougth the best results. 5. The strength ratio ($\sigma$b/$\sigma$c and $\sigma$t/$\sigma$c) increased, when steel fiber's average spacing was up to 3.05mm, but decreased when beyond 3.05mm, and it was confirmed that tensile or flexural strengths of steel fiber reinforced concrete are apparently governed by fiber's average spacing. 6. The compressive strain of fiber reinforced concrete showed a significant increasing tendency as the fiber was added, but Young's modulus. with the addition of steel and glass fibers, showed a slight decrease tendency. And according to the increase of flexural strength, a considerable increase was seen in toughness. 7. With the addition of fiber's the shrinkage of concrete was significantly decreased, in both case of adding steel fibers 12.5%, 30mm, and showed a significant decrease ratio, in average 30.4% and 36.7%, as compared with plain concrete. 8. With the increase of fiber volume fraction and length, the gained stress in reinforcing bar in concrete specimens increased in all crack widths, but at different rates, with the decrease of fiber diameter, the stress showed a considerable increasing tendency. And the duoform steel fibers showed the greatest improvement, as compared with the other types tested. 9. The influence of fiber dimensions in order of significanse on the machanical properties of concrete and the crack control of reinforced concrete was explained as follows: content, length, aspect ratio and dimeter.

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Clinical characteristics of severe respiratory syncytial virus infection requiring mechanical ventilation in neonatal period and early infancy (신생아기와 조기 영아기에 발생한 기계환기요법이 필요했던 중증 respiratory syncytial virus 감염의 임상적 특성)

  • Shin, Seung Han;Kim, Jae Ri;Lee, Jin-A;Choi, Chang Won;Kim, Ee-Kyung;Choi, Eun Hwa;Kim, Han-Suk;Kim, Beyong Il;Lee, Hoan Jong;Choi, Jung Hwan
    • Clinical and Experimental Pediatrics
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    • v.51 no.4
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    • pp.372-376
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    • 2008
  • Purpose : To identify clinical characteristics of severe respiratory syncytial virus (RSV) in neonatal period and early infancy and provide information in clinical practice. Methods : Twelve neonates and young infants (<6 months) who were infected by respiratory syncytial virus and required mechanical ventilation between March 2005 and July 2007 were enrolled. Diagnosis of RSV infection was made based on the positive results by rapid antigen immunoassay or polymerase chain reaction. Results : There were four premature infants, of whom three were near-term. Birth weight of subject patients was $2.8{\pm}0.6kg$, gestational age was $37{\pm}2weeks$ and the age at the time of admission was $35{\pm}15days$. Nine of them showed apnea and in five patients, apnea itself was an indication for mechanical ventilation. In seven of the apneic patients, apnea was the first manifestation of RSV infection. In three of these seven apneic patients, apnea preceded definite respiratory distress signs or typical stethoscopic findings by 1-3 days. Mean duration of mechanical ventilation was $3{\pm}2days$, and mean duration of stay in intensive care unit was $6{\pm}2days$. Conclusion : RSV is a major cause of severe respiratory tract infection in term or near-term infant younger than 2 months. For apnea could be the first manifestation of the RSV infection, high level of suspicion is required in practice of neonates or young infants who show any upper respiratory infection symptoms during RSV season.