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A study on the classification of research topics based on COVID-19 academic research using Topic modeling (토픽모델링을 활용한 COVID-19 학술 연구 기반 연구 주제 분류에 관한 연구)

  • Yoo, So-yeon;Lim, Gyoo-gun
    • Journal of Intelligence and Information Systems
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    • v.28 no.1
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    • pp.155-174
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    • 2022
  • From January 2020 to October 2021, more than 500,000 academic studies related to COVID-19 (Coronavirus-2, a fatal respiratory syndrome) have been published. The rapid increase in the number of papers related to COVID-19 is putting time and technical constraints on healthcare professionals and policy makers to quickly find important research. Therefore, in this study, we propose a method of extracting useful information from text data of extensive literature using LDA and Word2vec algorithm. Papers related to keywords to be searched were extracted from papers related to COVID-19, and detailed topics were identified. The data used the CORD-19 data set on Kaggle, a free academic resource prepared by major research groups and the White House to respond to the COVID-19 pandemic, updated weekly. The research methods are divided into two main categories. First, 41,062 articles were collected through data filtering and pre-processing of the abstracts of 47,110 academic papers including full text. For this purpose, the number of publications related to COVID-19 by year was analyzed through exploratory data analysis using a Python program, and the top 10 journals under active research were identified. LDA and Word2vec algorithm were used to derive research topics related to COVID-19, and after analyzing related words, similarity was measured. Second, papers containing 'vaccine' and 'treatment' were extracted from among the topics derived from all papers, and a total of 4,555 papers related to 'vaccine' and 5,971 papers related to 'treatment' were extracted. did For each collected paper, detailed topics were analyzed using LDA and Word2vec algorithms, and a clustering method through PCA dimension reduction was applied to visualize groups of papers with similar themes using the t-SNE algorithm. A noteworthy point from the results of this study is that the topics that were not derived from the topics derived for all papers being researched in relation to COVID-19 (

    ) were the topic modeling results for each research topic (
    ) was found to be derived from For example, as a result of topic modeling for papers related to 'vaccine', a new topic titled Topic 05 'neutralizing antibodies' was extracted. A neutralizing antibody is an antibody that protects cells from infection when a virus enters the body, and is said to play an important role in the production of therapeutic agents and vaccine development. In addition, as a result of extracting topics from papers related to 'treatment', a new topic called Topic 05 'cytokine' was discovered. A cytokine storm is when the immune cells of our body do not defend against attacks, but attack normal cells. Hidden topics that could not be found for the entire thesis were classified according to keywords, and topic modeling was performed to find detailed topics. In this study, we proposed a method of extracting topics from a large amount of literature using the LDA algorithm and extracting similar words using the Skip-gram method that predicts the similar words as the central word among the Word2vec models. The combination of the LDA model and the Word2vec model tried to show better performance by identifying the relationship between the document and the LDA subject and the relationship between the Word2vec document. In addition, as a clustering method through PCA dimension reduction, a method for intuitively classifying documents by using the t-SNE technique to classify documents with similar themes and forming groups into a structured organization of documents was presented. In a situation where the efforts of many researchers to overcome COVID-19 cannot keep up with the rapid publication of academic papers related to COVID-19, it will reduce the precious time and effort of healthcare professionals and policy makers, and rapidly gain new insights. We hope to help you get It is also expected to be used as basic data for researchers to explore new research directions.

  • Home Range and Behavioral Characteristics of released the sika deer(Cervus nippon) by using GPS Collar in Songnisan National Park (속리산국립공원에 방사된 꽃사슴(Cervus nippon)의 GPS collar를 이용한 행동권, 서식지 이용특성 분석)

    • Kim, Gyu-Cheol;Lee, Yong-Hak;Jung, Dae-Ho;Kim, Ki-Yoon;Kim, Young-hun;Han, Hye-seong;Son, Jang-Ick;Lee, Ju-hyeong;Lee, Han-ung;Cho, Seon-guk;Cho, Chea-Un
      • Korean Journal of Environment and Ecology
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      • v.30 no.6
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      • pp.962-969
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      • 2016
    • This study assessed the ecological and behavioral characteristics of the sika deer from April 2012 to August 2016. To obtain basic information on the behavioral patterns of the sika deer (Cervus nippon) including their annual home range, sika deer wearing GPS tracking collars were released into 1,385 locations at a different altitude around where they had been captured in Songnisan. The released individuals were studied through home range analysis. According to our observations, annual home ranges of the sika deer (n=6) is seen to be $2.24{\pm}1.50km^2$ (t=3.648, p<0.05) of MCP 95% for the entire area of home range and $0.46{\pm}0.31km^2$ (t=3.666, p<0.05)$km^2$ of FK 50% for the home range core area respectively. The annual home ranges of the sika deers by sex were $2.94km^2$ for female and $1.53km^2$ for male. This study is expected to provide basic data for habitat management and ecological study of sika deer and to contribute to the management of wild animals.

    Genotoxicity and Mutagenicity of the Extracts of Morus alba L. (뽕나무 추출물의 유전독성 및 돌연변이원성)

    • Jin, Hyou-Ju;Lee, Hyeon-Yong;Kim, Jong-Dai;Heo, Moon-Young;Lee, Jin-Ha
      • Korean Journal of Medicinal Crop Science
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      • v.13 no.6
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      • pp.217-225
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      • 2005
    • This study was carried out to investigate the genotoxicity in comet and in vitro micronucleus assay and mutagenicity in Ames test of the extracts from leaves and stem of Morus alba L. The samples showed a very weak cytotoxicity on the NIH/3T3 cells by SRB assay. The cell viability of the extracts and fractions from leaves and stems of Morus alba L. was 80% over at $500\;{\mu}g/ml$, and that of the chloroform fractions from leaves and stems showed lower than others. The genotoxicity at $250\;{\mu}g/ml$ of 100% EtOH and water extracts on the NIH/3T3 cells in comet assay was about 40% compared to positive control, and most fractions from 100% EtOH extract of the leaves showed stronger genotoxicity than that offractions from the stem. The genotoxicity with S-9 mix in vitro micronucleus assay of the 100% EtOH and water extracts form Morus alba L. did not indicate any significant difference as compared with control group. The cytokinesis-binucleated cells were showed in the hexan, chloroform, ethylacetate and butanol fractions from the extract of the leaves without S-9, and sample with S-9 showed CB cells in the chloroform fraction from the leaves. In the Ames test, the water and 100% ethanol extracts of Morus alba L. did not have a strong mutagenicity in TA98 and TA100, but the fractions of organic solvents of the ethanol extract had $10{\sim}26%$ of mutagenicity on the TA100 strain.

    Effect of Yeongyupaedog-san on Cytokine Levels of Mouse Th1/Th2 Cells and Anti-allergic Activity in Ovalbumin-sensitized Allergic Inflammation Model (연교적패독산(連翹敗毒散) 물 추출물(抽出物)의 마우스 Th1/Th2 사이토카인 조절(調節)에 의한 항알레르기 효과)

    • Khwag, Nyo-Gyu;Kang, Hee;Myung, Eu-Gene;Park, Sung-Min;Shim, Bum-Sang;Kim, Sung-Hoon;Choi, Seung-Hoon;Ahn, Kyoo-Seok
      • Journal of Physiology & Pathology in Korean Medicine
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      • v.20 no.4
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      • pp.844-852
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      • 2006
    • This study was to evaluate the effect of Yeongyupaedog-san (YGPDS) on mouse Thl and Th2 cells' differentiation and ovalbumin (OVA)-induced allergic inflammation. The proliferation of mouse CD4 T cells and the secretion of Th1/Th2 cytokines under the influence of YGPDS extract were measured as well as the amount of ${\beta}-hexosaminidase$ in RBL-2H3 cells and the levels of $TNF-{\alpha}$ and 1L-6 secretion in Raw264.7 cells. BALB/c mice were orally administered with YGPDS extract and simultaneously inoculated with OVA to induce allergic reaction and measure the level of total IgE, OVA-specific IgE and the production of IFN- g, IL-4, IL-5 by the spleen cells. When mouse CD4 T cell were stimulated with anti-CD3 and anti-CD28 for 48 hours in various concentrations of YGPDS extract, it increased proliferation of CD4 cells by 11% in $100\;{\mu}g/^{ml}$ concentration but it showed an inhibition by 37% at $200\;{\mu}g/^{ml}$ CD4 T cells under Th1/Th2 polarizing conditions for 3 days with YGPDS resulted in mild decrease of IFN- g in Thl cells and significant decrease of IL-4 in Th2 cells at $500\;{\mu}g/^{ml}\;and\;100\;{\mu}g/^{ml}$ by 18% and 21%, respectively. YGPDS extract had a dose-dependent inhibitory effect on antigen-induced release of ${\beta}-hexosaminidase$ in RBL-2H3 cells. Treatment of YGPDS extract on LPS stimulated Raw 264.7 cells showed dose-dependent decrease in TNF-n production. Oral administration of YGPDS extract on OVA-induced allergic mice showed an inhibitory effect on the levels of total serum IgE and OVA-specific IgE by 25% and 34% , respectively. Culture of spleen cells with OVA resulted in significant increase of IFN- g by 44% and significant decrease of IL-4 and IL-5 by 56%, and 24%, respectively. The results show that YGPDS does not strongly induce mouse T cells to transform into Thl or Th2 but it has an anti-allergic effect in vitro, and that it also corrects the unbalance between the reactions of Th cells in allergic diseases.

    Antimutagenicity and Immuno Activity of Extracts from Epimedium koreanum Nakai Containing Different Icariin Quantity (Icariin 함량에 따른 삼지구엽초 추출물의 항돌연변이 및 면역활성)

    • Park, Myoung-Su;Kim, Seo-Jin;Forghani, Fereidoun;Rahman, S.M.E.;Eo, Ji-Hyun;Eun, Jong-Bang;Oh, Deog-Hwan
      • Food Science and Preservation
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      • v.18 no.6
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      • pp.938-945
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      • 2011
    • Epimedium koreanum Nakai is a wild herb commonly consumed in South Korea due to its beneficial health effects. In the present study, the antimutagenic and immunoactivities of extracts from E. koreanum Nakai containing different icariin quantities were investigated for food use. In the Ames test, both the water and ethanol extracts were found not to have a mutagenic effect on Salmonella typhimurium TA98 and TA100, respectively. The E. koreanum Nakai extracts showed over 80 and 90% antimutagenic effects on benzo(${\alpha}$)pyrene (B(a)P) in S. typhimurium TA98 and TA100, respectively. Moreover, all the extracts showed over 70% antimutagenicity on S. typhimurium TA98 and TA100 against 4-nitroquinoline-1-oxide (4NQO). The E. koreanum Nakai extract with ethanol showed strong antimutagenic activity, higher than that of the water extract and the sequenced KE9412, KE9408, and KE9405. In the immunomodulating activity test, the effect of E. koreanum Nakai on the B (Rhamos) and T (Jukat) cells were investigated. The immunoactivity results showed that the growth and viability of the B and T cells increased and were activated more in KE9405 (1.8 times), KE9408 (1.6 times), and KE9412 (1.32 times) in the water extracts, and least in KE9412 (1.74 times), KE9408 (1.52 times), and KE9405 (1.4 times) in the ethanol extracts. In the case of both the water and ethanol extracts ($500{\mu}g/mL$) from E. koreanum Nakai, the highest cell number of the human B (Rhamos) and T (Jukat) cells was observed on day 4 in KE9405 and KE9412, and on day 5 in KE9408. Based on the obtained results, the development of E. koreanum Nakai as a food material is recommended.

    Anti-obesity effect of radish leaf extracts on high fat diet-induced obesity in mice (고지방식이를 통해 비만이 유발된 마우스에서 무청 추출물의 항비만 효과)

    • Lee, Yun-Seong;Seo, Young Ho;Kim, Ji Yong
      • Korean Journal of Food Science and Technology
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      • v.54 no.3
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      • pp.297-305
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      • 2022
    • The goal of this study was to evaluate the anti-obesity effect of radish leaf extracts (MU-C) and radish leaf extracts with 3% citric acid (MU-CA) in a high-fat diet (HFD)-induced C57BL/6 mice. The effects of radish leaf extracts on adipogenesis were also investigated using 3T3-L1 adipocytes. As determined by Oil red O staining, MU-C inhibited adipogenesis in 3T3-L1 adipocytes. Four-week-old male C57BL/6 mice were fed an HFD for 6 weeks and then treated with radish leaf extracts (500 mg/kg, p.o.) for 6 weeks. Then, the serum levels of Aspartate aminotransferase, Alanine aminotransferase, Total cholesterol, Triglyceride and low-density lipoprotein cholesterol in the mice were measured using an automatic chemical analyzer and enzyme-linked immunosorbent assay. Administration of MU-C significantly reduced the fat weight when compared with HFD controls. As confirmed by histopathologic analysis, adipose tissue size markedly decreased in mice treated with MU-C. Therefore, this study could provide a basis for investigating the clinical use of MU-C as an agent for preventing obesity.

    Effects of applied biochar derived from spent oyster mushroom (Pleurotus ostreatus) substrate to Soil Physico-chemical Properties and crop growth responses (느타리버섯 수확후배지 바이오차 시용이 토양 이화학성 및 작물 생육에 미치는 영향)

    • Jae-Eun Jang;Sung-Hee Lim;Min-Woo Shin;Ji-Young Moon;Joo-Hee Nam;Gab-June Lim
      • Journal of the Korea Organic Resources Recycling Association
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      • v.31 no.3
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      • pp.73-82
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      • 2023
    • This study was conducted to investigate the effect of soil physico-chemical properties and crop growth responses for application of biochar derived from substrate with post harvest of oyster mushroom. The biochar was produced at 450~600℃ using a top-light up draft gasifier (TLUD) production system. As a result of elemental analysis, the biochar used was C 76.2%, H 2.5%, N 3.2%, and H/C was 0.39, which met the international certification standards for biocarbons (IBI) below 0.7. The chemical properties were 10.1 for pH, 1.0% for P2O5, 1.8% for K2O, and 2.5% for CaO. The application rates of biochar were 0, 100, 200, 300, and 500 kg/10a. For cultivation of chinese cabbage and welsh onion, soil organic matter (OM), total nitrogen (T-N), total carbon (T-C), Ex.cation K contents and cation exchange capacity (CEC) in the treatments were increased compared to the no treatment. In addition, the bulk density was lowered and the porosity was increased, improving the soil physical properties in the treated soil. The growth of chinese cabbage and green onion increased with the application of biochar, but the yields of chinese cabbage and green onion did not significantly different among the treatments. Soil carbon sequestration in the treatments enhanced with increasing the amount of biochar application. It is expected to apply the biochar derived from spent oyster mushroom substrate in the eco-friendly farm soil management, improving soil physico-chemical properties.

    Studies on the Physical and Chemical Denatures of Cocoon Bave Sericin throughout Silk Filature Processes (제사과정 전후에서의 견사세리신의 물리화학적 성질변화에 관한 연구)

    • 남중희
      • Journal of Sericultural and Entomological Science
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      • v.16 no.1
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      • pp.21-48
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      • 1974
    • The studies were carried out to disclose the physical and chemical properties of sericin fraction obtained from silk cocoon shells and its characteristics of swelling and solubility. The following results were obtained. 1. The physical and chemical properties of sericin fraction. 1) In contrast to the easy water soluble sericin, the hard soluble sericin contains fewer amino acids include of polar side radical while the hard soluble amino acid sach as alanine and leucine were detected. 2) The easy soluble amino acids were found mainly on the outer part of the fibroin, but the hard soluble amino acids were located in the near parts to the fibroin. 3) The swelling and solubility of the sericin could be hardly assayed by the analysis of the amino acid composition, and could be considered to tee closely related to the compound of the sericin crystal and secondary structure. 4) The X-ray patterns of the cocoon filament were ring shape, but they disappeared by the degumming treatment. 5) The sericin of tussah silkworm (A. pernyi), showed stronger circular patterns in the meridian than the regular silkworm (Bombyx mori). 6) There was no pattern difference between Fraction A and B. 7) X-ray diffraction patterns of the Sericin 1, ll and 111 were similar except interference of 8.85A (side chain spacing). 8) The amino acids above 150 in molecular weight such as Cys. Tyr. Phe. His. and Arg. were not found quantitatively by the 60 minutes-hydrolysis (6N-HCI). 9) The X-ray Pattern of 4.6A had a tendency to disappear with hot-water, ether, and alcohol treatment. 10) The partial hydrolysis of sericin showed a cirucular interference (2A) on the meridian. 11) The sericin pellet after hydrolysis was considered to be peptides composed with specific amino acids. 12) The decomposing temperature of Sericin 111 was higher than that of Sericin I and II. 13) Thermogram of the inner portioned sericin of the cocoon shell had double endothermic peaks at 165$^{\circ}C$, and 245$^{\circ}C$, and its decomposing temperature was higher than that of other portioned sericin. 14) The infrared spectroscopic properties among sericin I, II, III and sericin extracted from each layer portion of the cocoon shell were similar. II. The characteristics of seriein swelling and solubility related with silk processing. 1) Fifteen minutes was required to dehydrate the free moisture of cocoon shells with centrifugal force controlled at 13${\times}$10$^4$ dyne/g at 3,000 R.P.M. B) It took 30 minutes for the sericin to show positive reaction with the Folin-Ciocaltue reagent at room temperature. 3) The measurable wave length of the visible radiation was 500-750m${\mu}$, and the highest absorbance was observed at the wave length of 650m${\mu}$. 4) The colorimetric analysis should be conducted at 650mu for low concentration (10$\mu\textrm{g}$/$m\ell$), and at 500m${\mu}$ for the higher concentration to obtain an exact analysis. 5) The absorbing curves of sericin and egg albumin at different wave lengths were similar, but the absorbance of the former was slightly higher than that of the latter. 6) The quantity of the sericin measured by the colorimetric analysis, turned out to be less than by the Kjeldahl method. 7) Both temperature and duration in the cocoon cooking process has much effect on the swelling and solubility of the cocoon shells, but the temperature was more influential than the duration of the treatment. 8) The factorial relation between the temperature and the duration of treatment of the cocoon cooking to check for siricin swelling and solubility showed that the treatment duration should be gradually increased to reach optimum swelling and solubility of sericin with low temperature(70$^{\circ}C$) . High temperature, however, showed more sharp increase. 9) The more increased temperature in the drying of fresh cocoons, the less the sericin swelling and solubility were obtained. 10) In a specific cooking duration, the heavier the cocoon shell is, the less the swelling and solubility were obtained. 11) It was considered that there are differences in swelling or solubility between the filaments of each cocoon layer. 12) Sericin swelling or solubility in the cocoon filament was decreased by the wax extraction.. 13) The ionic surface active agent accelerated the swelling and solubility of the sericin at the range of pH 6-7. 14) In the same conditions as above, the cation agent was absorbed into the sericin. 15) In case of the increase of Ca ang Mg in the reeling water, its pH value drifted toward the acidity. 16) A buffering action was observed between the sericin and the water hardness constituents in the reeling water. 17) The effect of calcium on the swelling and solubility of the sericin was more moderate than that of magnecium. 18) The solute of the water hardness constituents increased the electric conductivity in the reeling water.

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    Relationships Among Employees' IT Personnel Competency, Personal Work Satisfaction, and Personal Work Performance: A Goal Orientation Perspective (조직구성원의 정보기술 인적역량과 개인 업무만족 및 업무성과 간의 관계: 목표지향성 관점)

    • Heo, Myung-Sook;Cheon, Myun-Joong
      • Asia pacific journal of information systems
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      • v.21 no.4
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      • pp.63-104
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      • 2011
    • The study examines the relationships among employee's goal orientation, IT personnel competency, personal effectiveness. The goal orientation includes learning goal orientation, performance approach goal orientation, and performance avoid goal orientation. Personal effectiveness consists of personal work satisfaction and personal work performance. In general, IT personnel competency refers to IT expert's skills, expertise, and knowledge required to perform IT activities in organizations. However, due to the advent of the internet and the generalization of IT, IT personnel competency turns out to be an important competency of technological experts as well as employees in organizations. While the competency of IT itself is important, the appropriate harmony between IT personnel's business capability and technological capability enhances the value of human resources and thus provides organizations with sustainable competitive advantages. The rapid pace of organization change places increased pressure on employees to continually update their skills and adapt their behavior to new organizational realities. This challenge raises a number of important questions concerning organizational behavior? Why do some employees display remarkable flexibility in their behavioral responses to changes in the organization, whereas others firmly resist change or experience great stress when faced with the need to alter behavior? Why do some employees continually strive to improve themselves over their life span, whereas others are content to forge through life using the same basic knowledge and skills? Why do some employees throw themselves enthusiastically into challenging tasks, whereas others avoid challenging tasks? The goal orientation proposed by organizational psychology provides at least a partial answer to these questions. Goal orientations refer to stable personally characteristics fostered by "self-theories" about the nature and development of attributes (such as intelligence, personality, abilities, and skills) people have. Self-theories are one's beliefs and goal orientations are achievement motivation revealed in seeking goals in accordance with one's beliefs. The goal orientations include learning goal orientation, performance approach goal orientation, and performance avoid goal orientation. Specifically, a learning goal orientation refers to a preference to develop the self by acquiring new skills, mastering new situations, and improving one's competence. A performance approach goal orientation refers to a preference to demonstrate and validate the adequacy of one's competence by seeking favorable judgments and avoiding negative judgments. A performance avoid goal orientation refers to a preference to avoid the disproving of one's competence and to avoid negative judgements about it, while focusing on performance. And the study also examines the moderating role of work career of employees to investigate the difference in the relationship between IT personnel competency and personal effectiveness. The study analyzes the collected data using PASW 18.0 and and PLS(Partial Least Square). The study also uses PLS bootstrapping algorithm (sample size: 500) to test research hypotheses. The result shows that the influences of both a learning goal orientation (${\beta}$ = 0.301, t = 3.822, P < 0.000) and a performance approach goal orientation (${\beta}$ = 0.224, t = 2.710, P < 0.01) on IT personnel competency are positively significant, while the influence of a performance avoid goal orientation(${\beta}$ = -0.142, t = 2.398, p < 0.05) on IT personnel competency is negatively significant. The result indicates that employees differ in their psychological and behavioral responses according to the goal orientation of employees. The result also shows that the impact of a IT personnel competency on both personal work satisfaction(${\beta}$ = 0.395, t = 4.897, P < 0.000) and personal work performance(${\beta}$ = 0.575, t = 12.800, P < 0.000) is positively significant. And the impact of personal work satisfaction(${\beta}$ = 0.148, t = 2.432, p < 0.05) on personal work performance is positively significant. Finally, the impacts of control variables (gender, age, type of industry, position, work career) on the relationships between IT personnel competency and personal effectiveness(personal work satisfaction work performance) are partly significant. In addition, the study uses PLS algorithm to find out a GoF(global criterion of goodness of fit) of the exploratory research model which includes a mediating variable, IT personnel competency. The result of analysis shows that the value of GoF is 0.45 above GoFlarge(0.36). Therefore, the research model turns out be good. In addition, the study performs a Sobel Test to find out the statistical significance of the mediating variable, IT personnel competency, which is already turned out to have the mediating effect in the research model using PLS. The result of a Sobel Test shows that the values of Z are all significant statistically (above 1.96 and below -1.96) and indicates that IT personnel competency plays a mediating role in the research model. At the present day, most employees are universally afraid of organizational changes and resistant to them in organizations in which the acceptance and learning of a new information technology or information system is particularly required. The problem is due' to increasing a feeling of uneasiness and uncertainty in improving past practices in accordance with new organizational changes. It is not always possible for employees with positive attitudes to perform their works suitable to organizational goals. Therefore, organizations need to identify what kinds of goal-oriented minds employees have, motivate them to do self-directed learning, and provide them with organizational environment to enhance positive aspects in their works. Thus, the study provides researchers and practitioners with a matter of primary interest in goal orientation and IT personnel competency, of which they have been unaware until very recently. Some academic and practical implications and limitations arisen in the course of the research, and suggestions for future research directions are also discussed.

    Situation of Fertilizer Industry in Korea (비료산업(肥料産業)의 현황(現況)과 문제점(問題点))

    • Lee, Yun Hwan
      • Korean Journal of Soil Science and Fertilizer
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      • v.15 no.1
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      • pp.34-48
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      • 1982
    • 1. Production and consumption of chemical fertilizers in Korea could be divided into five different phases of total imports, setting up fertilizer plants, self-sufficiency in production, net export, and diversification in compound fertilizers. Currently the nation has production capacity of 800 thousand M/T of nitrogen, 400 thousand M/T of phosphate ($P_2O_5$) and 200 thousand M/T of potash ($K_2O$). 2. Yearly consumption increased every year, since 1964, 28,000 M/T N, 7,700 M/T $P_2O_5$, and 7,500 M/T $K_2O$ until 1972, when the increase jumped by eight times for $P_2O_5$ and seven times for $K_2O$ for the following 3 years in anticipation of their short supply. Now total consumption has been more or less stabilized at the level of 450 thousand M/T N, 220 thousand M/T $P_2O_5$ and 180 thousand M/T $K_2O$ for the last 7 years. 3. Current operation rate of fertilizer plants is around 80% throughout the whole industry, after going through several different levels depending on demand at times. 4. Fertilizer export started in 1967 and reached a peak of 150 thousand nutrient ton in 1972, about 20% of total production, before temporarily stopping due to over-demand for next three years. The export resumed again in 1976 rise to the all time high of 670 thousand nutrient ton in 1980, almost half of total production, and then started to decline due to higher price of petroleum since then. 5. The decline in fertilizer export appears to be accelerated because several countries, in South-Eastern Asia, traditional export market for Korean fertilizers, started to build their own plants, since 1980, based on their raw materials of especially petroleum. 6. Current consumption in Korea is about 30 nutrient Kg per 10a, equivalent to that in Western European countries, partly due to new high-yielding rice varieties and extensive cultivation of fruit trees and vegetables. Additional fertilizer demand in future can be anticipated in reclaimed land for growing grass and forestry.

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