• Journal of Microbiology and Biotechnology
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• 제25권3호
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• pp.366-374
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• 2015

Herein, we established a repeated-batch process for ethanol production from glycerol by immobilized Pachysolen tannophilus. The aim of this study was to develop a more practical and applicable ethanol production process for biofuel. In particular, using industrial-grade medium ingredients, the microaeration rate was optimized for maximization of the ethanol production, and the relevant metabolic parameters were then analyzed. The microaeration rate of 0.11 vvm, which is far lower than those occurring in a shaking flask culture, was found to be the optimal value for ethanol production from glycerol. In addition, it was found that, among those tested, Celite was a more appropriate carrier for the immobilization of P. tannophilus to induce production of ethanol from glycerol. Finally, through a repeated-batch culture, the ethanol yield (Y_e/g) of 0.126 ± 0.017 g-ethanol/g-glycerol (n = 4) was obtained, and this value was remarkably comparable with a previous report. In the future, it is expected that the results of this study will be applied for the development of a more practical and profitable long-term ethanol production process, thanks to the industrial-grade medium preparation, simple immobilization method, and easy repeated-batch operation.

• Reproductive and Developmental Biology
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• 제33권3호
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• pp.133-137
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• 2009

Pluripotent embryonic stem (ES) cells isolated from inner cell mass (ICM) of blastocyst-stage embryos are capable of differentiating into various cell lineages and demonstrate germ-line transmission in experimentally produced chimeras. These cells have a great potential as tools for transgenic animal production, screening of newly-developed drugs, and cell therapy. Miniature pigs, selectively bred pigs for small size, offer several advantages over large breed pigs in biomedical research including human disease model and xenotransplantation. In the present study, factors affecting primary culture of somatic cell nuclear transfer blastocysts from miniature pigs for isolation of ES cells were investigated. Formation of primary colonies occurred only on STO cells in human ES medium. In contrast, no ICM outgrowth was observed on mouse embryonic fibroblasts (MEF) in porcine ES medium. Plating intact blastocysts and isolated ICM resulted in comparable attachment on feeder layer and primary colony formation. After subculture of ES-like colonies, two putative ES cell lines were isolated. Colonies of putative ES cells morphologically resembled murine ES cells. These cells were maintained in culture up to three passages, but lost by spontaneous differentiation. The present study demonstrates factors involved in the early stage of nuclear transfer ES cell isolation in miniature pigs. However, long-term maintenance and characterization of nuclear transfer ES cells in miniature pigs are remained to be done in further studies.

• Journal of Korea Trade
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• 제27권1호
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• pp.60-78
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• 2023

Purpose - The study analyzed 90 online firms worldwise and observed them for ten years to investigate their investments and firm performance variabilities. This study attemped to verify the existence of agency problems in online firms. Through this, the paper intends to expand the scope of research in the fields of investment and firm value both empirically and in theory. This study also attempted to supplement the insufficient logic of previous studies by analyzing the relationship between investment and profitability. Design/methodology - In this study, the investment is subdivided into over-, under-, and neutral investments, and an empirical analysis of the firm performance was conducted. As investment generally has long-term effects, the impact of a firm's investment on future firm performance and variabilities in firm performance was considered over the short-and medium-term period. Findings - It was found that there was a negative relationship between firms with an overinvestment and future firm performance. Underinvestment has no clear statistically significant results on firm performance. This implies that overinvestment causes more reduction in future firm performance than underinvestment. It was also found that underinvestment and overinvestment significantly increased the variability of firm performance. A positive significance was found between under- and over- investment with a variability of 3 years and overinvestment with a variability of 4 years in the future. A negative relationship was found between neutral investment propensity and future performance variabilities. Neutral investment has less effect on the future performance variability of a firm than a firm's overinvestment and underinvestment. For online firms, underinvestment and overinvestment have a greater effect on the firm's future performance variability than neutral investment. Originality/value - The agency theory predicts that information asymmetry and adverse selection problems exacerbate conflicts of interest among stakeholders, thus firm performance. The study contributed to accumulating research on online firms that are currently underexplored by analyzing the investment behavior of major firms in the online industry.

• 수산경영론집
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• 제48권2호
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• pp.19-32
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• 2017

The purpose of this study is to identify problems and suggest improvements of estimating procedures and item of fisheries supply-demand statistics served as a basis for the fisheries supply-demand policies. Korea Rural Economic Institute(KREI) and Ministry of Oceans and Fisheries(MOF) respectively publish the fisheries supply-demand statistics. But the reliability of data is low as the statistics of these two organizations are limited and show discrepancy in the numbers. It is therefore difficult to use them as the basic data for policies. Also, an accurate data aggregation is difficult due to following problems in the items of statistics. 1) Problems in estimating route sales and non-route sales of production, 2) adequacy of fishery product yield rate compared to raw material in the fisheries import/export sector, 3) selection of target companies for understand stocks and survey scope of fish species, 4) applying'0'to non-edible product demand etc. In order to develop the fisheries industry as a future growth industry, it is necessary to establish the accurate fisheries supply-demand policy as the instability of fisheries supply and demand is increasing. To do this, statistical reliability has to be improved. The improvements proposed in this study should be implemented considering urgency. First of all, an exhaustive analysis of stock statistics and conversion rates of raw material yield in the fisheries import/export sector should be conducted. In the medium term and the long term, transferring production statistics to MOF and surveys on the use demand of non-food product and the level of reduced and discarded seafood products should be carried out in consecutive order.

• 한국직업건강간호학회지
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• 제9권2호
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• pp.155-165
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• 2000

This study is to grope for a plan to increase nurse's autonomy by grasping autonomy degree according to nursing delivery system. The subject of this study are 265 nurses who work for 4 general hospitals in Seoul, and 73 of them work in primary nursing delivery system, 99 of them in team nursing delivery system and 93 of them in functional nursing delivery system. Data collection was done through questionaires from Sep. 1, 1997 to Sep. 30, 1997, and autonomy was measured by Professional Nursing Autonomy Scale developed by Schutzonhofer. Data analysis as inspected with $X^2$ test, ANOVA, and t-test, using SPSS program. The results are as follows : 1. When it comes to the autonomy of all the nurses, mean score was 161.99. Which is medium level, and autonomy degree according to nursing delivery system had no significant differences. 2. There was a significant difference in autonomy degree according to inservice education among the subject's work-related characteristics, and there was no significant difference in autonomy distribution in each grade according to general characteristics although older group, married group, and junior college graduates group showed rather higher trends. 3. Considering each item, questions related to direct nursing such as "Vital sign monitoring", "Nursing rounding", "Withhold contraindicated drug", showed high score in autonomy scores, and long-term and indirect nursing behaviors such as "Nursing administration", "Nursing research", "Follow-up care" and "Educational planning".

• 대기
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• 제29권1호
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• pp.53-59
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• 2019

The quality of troposphere ozone in three reanalysis datasets is evaluated with longterm ozonesonde measurement at Pohang, South Korea. The Monitoring Atmospheric Composition and Climate (MACC), European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERAI) and Modern Era Retrospective-Analysis for Research and Applications version 2 (MERRA2) are particularly examined in terms of the vertical ozone structure, seasonality and long-term trend in the lower troposphere. It turns out that MACC shows the smallest biases in the ozone profile, and has realistic seasonality of lower-tropospheric ozone concentration with a maximum ozone mixing ratio in spring and early summer and minimum in winter. MERRA2 also shows reasonably small biases. However, ERAI exhibits significant biases with substantially lower ozone mixing ratio in most seasons, except in mid summer, than the observation. It even fails to reproduce the seasonal cycle of lower-tropospheric ozone concentration. This result suggests that great caution is needed when analyzing tropospheric ozone using ERAI data. It is further found that, although not statistically significant, all datasets consistently show a decreasing trend of 850-hPa ozone concentration since 2003 as in the observation.

• Journal of Plant Biotechnology
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• 제7권1호
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• pp.75-80
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• 2005

Eleutherococcus senticosus (also called Acanthopanax senticosus), belonging to Araliaceae family, has been used as an important medicinal woody plant. Mature seeds of Eleutherococcus senticosus have rudimentary (extremely immature) zygotic embryos and require a long-term stratification for about 18 months to induce germination. Here, through the methods of endosperm removal and other exogenous treatments, we investigated the factors for inducing rudimentary embryos by in vitro culture, Rudimentary zygotic embryos in seeds were at globular to heart-shaped stage at about $250{\mu}m$ in length just after harvest of fruits. When the seeds without testa were cultured on 1/2 MS (Murashige and Skoog 1962) medium, they did not germinate regardless of medium and sucrose concentrations but the removal of endosperm tissue markedly stimulated the growth of rudimentary zygotic embryos. The embryo reached ear-lier maturation, once when the endosperm surrounding the rudimentary embryos was removed. Rudimentary zygotic embryos developed cotyledons within 3 weeks of culture after endosperm emoval. However, post-mature zygotic embryos failed to germinate though they were morphologically normal, indicating another dormancy of embryos. $GA_3\;(2.0\;\cal{mg/L})$ and/or charcoal ($0.2\%$) treatment rapidly enhanced the germination of zygotic embryos. These results suggest that E. senticosus seeds have double dormancy; i. e. morphological rudimentary dormancy influenced by surrounding endosperm and physiological dormancy after post-maturation of zygotic embryos. Based on the above findings, we established the rapid germination of rudimentary zygotic embryos by in vitro culture of excised seeds with endosperm removal and $GA_3$ treatment.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.3268-3277
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• 2011

의왕ICD는 현대적 시설과 하역장비를 갖추어 연간 100만TEU를 처리 할 수 있는 수도권유일의 내륙컨테이너기지이다. 유리한 입지조건, 수도권 물류수송의 거점 역할, 내륙통관 기능 등 많은 이점을 가지고 있어 철도수송 활성화의 중요한 부분을 차지한다. 그러나 의왕ICD는 현재 시설 및 운영상의 문제점으로 컨테이너화물 철도수송 활성화의 한계에 있는 실정이다. 본 연구에서는 의왕ICD의 문제점을 시설부분과 운영부분으로 구분하여 분석하고, 2023년 점용허가 기간이 만료되는 시점을 기준으로 단기, 중장기로 구분하여 개선방안을 제시하였다. 그러나 의왕ICD의 철도수송 활성화는 이러한 개선방안 외에도 철도공사와 입주업체의 노력과함께, 정부, 의왕시, 철도시설공단 등 관련기관의 지원과 협력이 있어야만 가능 할 것이다. 이러한 의왕ICD의 개선은 복합일관수송체계를 구축하여 효율적인 철도물류 인프라 조성 및 철도물류 활성화에 기여하고, 또한 친환경 수송시스템 구축으로 정부의 저탄소 녹색성장 정책에도 기조 할 것으로 기대된다.

• 디지털융복합연구
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• 제10권1호
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• pp.341-347
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• 2012

본 연구에서는 연구개발정보의 체계적인 기록과 관리 그리고 기록물의 신뢰성 확보를 위해 전자연구노트 시스템을 구축 운영하기 위한 방향을 제시하고자 한다. 첫째 연구기관이나 기업이 전자연구노트를 사용하기 위해서는 전자연구노트 작성 및 관리를 위한 시스템 환경을 필요로 하므로 이에 대한 구축 표준안을 제시하였다. 둘째 구축된 전자연구노트 시스템의 체계적인 유지보수 및 운영을 위한 지침을 수립하였다. 셋째 구축되고 운영되고 있는 전자연구노트 시스템이 규정과 절차에 따라 적정하게 관리되고 있는지 여부를 점검하기 위한 지침을 마련하였다. 따라서 이러한 가이드라인 제시는 전자연구노트 활성화 및 중장기적으로 연구개발정보 활용기반 마련에 기여할 것으로 판단된다.

• 전기학회논문지
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• 제56권10호
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• pp.1715-1720
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• 2007

The CSC-based HVDC system links the Jeju system to the mainland system. Because CSC-based HVDC is installed in Jeju, the reactive power is needed to transfer active power through the HVDC. In order to supply reactive power, switched capacitors and synchronous condensers are installed in Jeju system. The deterioration of established synchronous condensers, however, causes a reactive power supply capability decline and high maintenance cost. It brings about the instability of Jeju system and the incremental of maintenance and repair costs. In the future the installation of wind generators and additional HVDC system would aggravate the stability of Jeju system. Therefore, it needs to consider a countermeasure against above problems. In this paper, Analysis of several contingencies of Jeju system was peformed, and some contingencies caused voltage-reactive power problem was known. CPF method was introduced in order to make countermeasures to replace the synchronous condensers and to solve the voltage-reactive power problem. The location and capacity of reactive power sources were also decided. It could guarantee medium and long term stability of Jeju system.