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Introduction of a Hybrid SFCL in KEPCO Grid and Local Points at Issue
Ok-Bae Hyun,Kwon-Bae Park,Jungwook Sim,Hye-Rim Kim,Seong-Woo Yim,Il-Sung Oh IEEE 2009 IEEE transactions on applied superconductivity Vol.19 No.3
<P>This report presents efforts for introducing a hybrid superconducting fault current limiter (SFCL) associated with the substation upgrade in the Korea Electric Power Corporation (KEPCO) grid and points at issue on the utility demands. The substation upgrade includes replacement of 154 kV/22.9 kV main transformers and applying 22.9 kV/3 kA SFCLs to protect them. The SFCL is expected to meet not only the general requirements, but also such local conditions as (1) small size to be installed in an in-house substation, (2) sustainable current limitation without the power line breaking by circuit breakers (CB) for maximum 2 seconds. Optionally, recommended are (3) the reclosing capability and semi-active function. Different types of currently developed SFCLs have been examined associated with the conditions. We have proposed a hybrid SFCL of first peak non-limiting type, which potentially fulfills all the local conditions. As an intermediate step, a 22.9 kV/630 A hybrid SFCL was built. This SFCL meets the field requirements of the size limit, 1.5 seconds sustainability of current limitation, 0.3 s reclosing capability and semi-active function. The upgraded hybrid SFCL will be installed in the KEPCO's test line for operation tests. There are two major test targets; long term operation test of the SFCL and protection coordination test using artificial faults.</P>
Cigarette Smoking and Risk of Lung Cancer in Korean Men: The Seoul Male Cancer Cohort Study
Bae, Jong-Myon,Lee, Moo-Song,Shin, Myung-Hee,Kim, Dong-Hyun,Li, Zhong-Min,Ahn, Yoon-Ok KOREAN ACADEMY OF MEDICAL SCIENCE 2007 JOURNAL OF KOREAN MEDICAL SCIENCE Vol.22 No.3
<P>Lung cancer is the leading cause of cancer deaths in Korea. The aim of this study was to estimate lung cancer risk of cigarette smoking in Korean men by a 10-yr follow-up prospective cohort study using the primary databases. The number of subjects was 14,272 men, who had full information of smoking habits among participants in the Seoul Male Cancer Cohort Study (SMCC). Total 125,053 person-years were calculated by determining the number of days from the start of follow-up, January 1, 1993, until the date of lung cancer diagnosis, death from another cause, or the end of follow-up, December 31, 2002, followed by converting the number of days to years. The information of outcome was obtained by the database of Korea Central Cancer Registry, Seoul Regional Cancer Registry, and Korea Statistical Office. The relative risk (RR) and its 95% confidence interval (CI) values of smoking were calculated using Cox proportional hazards regression stratified on potential confounders. During the follow-up periods, 78 cases of lung cancer occurred. The cigarette smoking is the major risk factor and increases the 4.18-fold risk of lung cancer in Korean men. In order to control lung cancer, intervention of quitting smoking is needed.</P>
Brief review of the field test and application of a superconducting fault current limiter
Hyun, Ok-Bae The Korea Institute of Applied Superconductivity a 2017 한국초전도저온공학회논문지 Vol.19 No.4
This article reviews the recent activities of field testing and application of superconducting fault current limiters (SFCL) based on high-temperature superconductors (HTS). The review particularly focuses on the trends in the field tests in terms of the technical aspects and commercial activities of the SFCLs. Stimulated by the discovery of HTS, numerous research and development activities have been conducted worldwide for SFCLs operating from distribution voltages to transmission voltages. Different types of SFCLs have been developed and field-tested. Consequently, more than 20 field tests and applications have been performed on real grids worldwide while supplying electric power to the customers. These field tests have not only provided the track records of the operation experiences including the problems and maintenance during operation, but also proved their current limiting capabilities against real faults, rendering this new technology highly viable. Through these activities, the following trends in the status of field testing and application are observed. Resistive-type SFCLs with HTS-coated conductors were dominantly used in the most recent field tests. This implies that the resistive type is technically more mature than the other types. Bus-bar coupling and transformer feeders were the major application locations. It is of importance that most of the field applications were conducted as R&D projects. A relevant change from the R&D stage to the application stage is shown as recently deployed SFCLs are expected to be under long-term operation and commercial service. Here, we review the installation of these SFCLs by substation. This review also discusses the recent activities for their commercial applications.
Hyun Dong-Wook,Lee Jae-Yun,Kim Min-Soo,Shin Na-Ri,Whon Tae Woong,Kim Kyung Hyun,Kim Pil Soo,Tak Euon Jung,Jung Mi-Ja,이준영,Kim Hyun Sik,Kang Woorim,Sung Hojun,Jeon Che Ok,Bae Jin-Woo 한국미생물학회 2021 The journal of microbiology Vol.59 No.8
Viridans group streptococci are a serious health concern because most of these bacteria cause life-threatening infections, especially in immunocompromised and hospitalized individuals. We focused on two alpha-hemolytic Streptococcus strains (I-G2 and I-P16) newly isolated from an ileostomy effluent of a colorectal cancer patient. We examined their pathogenic potential by investigating their prevalence in human and assessing their pathogenicity in a mouse model. We also predicted their virulence factors and pathogenic features by using comparative genomic analysis and in vitro tests. Using polyphasic and systematic approaches, we identified the isolates as belonging to a novel Streptococcus species and designated it as Streptococcus ilei. Metagenomic survey based on taxonomic assignment of datasets from the Human Microbiome Project revealed that S. ilei is present in most human population and at various body sites but is especially abundant in the oral cavity. Intraperitoneal injection of S. ilei was lethal to otherwise healthy C57BL/6J mice. Pathogenomics and in vitro assays revealed that S. ilei possesses a unique set of virulence factors. In agreement with the in vivo and in vitro data, which indicated that S. ilei strain I-G2 is more pathogenic than strain I-P16, only the former displayed the streptococcal group A antigen. We here newly identified S. ilei sp. nov., and described its prevalence in human, virulence factors, and pathogenicity. This will help to prevent S. ilei strain misidentification in the future, and improve the understanding and management of streptococcal infections.
Cigarette Smoking and Prostate Cancer Risk: Negative Results of the Seoul Male Cancer Cohort Study
Bae, Jong-Myon,Li, Zhong-Min,Shin, Myung-Hee,Kim, Dong-Hyun,Lee, Moo-Song,Ahn, Yoon-Ok Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.8
We evaluated cigarette smoking as a risk factor for prostate cancer in a prospective, population-based cohort study. The subjects were 14,450 males among the participants in the Seoul Male Cancer Cohort Study who had at least 1-year follow-up. They were followed up between 1993 and 2008. During the 16-year follow-up period, 87 cases of prostate cancer occurred over the 207,326 person-years of the study. The age-adjusted relative risks of past and current smokers at entry were 0.60 (95%CI: 0.34-1.06) and 0.70 (95%CI: 0.43-1.13), respectively, suggesting that cigarette smoking may not be a risk factor for prostate cancer. The relationship between prostate cancer and other modifiable factors, such as Westernized diet, should be studied with the goal of establishing prevention programs for prostate cancer.
Ok-Bae Hyun,Jungwook Sim,Hye-Rim Kim,Kwon-Bae Park,Seong-Woo Yim,Il-Sung Oh IEEE 2009 IEEE transactions on applied superconductivity Vol.19 No.3
<P>We have investigated reliability enhancement of the fast switch (FS) by using power electronic switches such as integrated gate commutated thyristors (IGCT) in the line commutation type hybrid superconducting fault current limiter (SFCL). The FS utilizes a vacuum interrupter (VI) to open and close the primary power line. The operation of the FS highly relies upon the complete line breaking by the VI. Since the primary line resistance including the arc resistance may not be extremely high after the VI opens, there may be non-zero arc current in the VI, causing a failure in the line communication. The IGCTs are to completely remove the remanent current in the VI, guaranteeing the arc extinction and enhancing reliability in operation. We fabricated and successfully tested the SFCL which was equipped with the IGCT-assisted FS.</P>
Ok-Tae Kim,Kyong-Hwan Bang,Young-Chang Kim,Yu-Su Shin,Dong-Yun Hyun,Byong-Yel Yeon,Yeoung-Seuk Bae,Nak-Sul Seong,Seon-Woo Cha 한국작물학회 2007 한국작물학회 학술발표대회 논문집 Vol.2007 No.11
Objectives Here, we report the effect of overexpression of ginseng farnesyl diphosphate synthase on the transcription of three key regulatory enzymes involved in triterpene metabolism in hairy root of ginseng and Centella asiatica (L.) Urban. Materials and Methods A four-year-old root of Panax ginseng C.A. Meyer and Centella asiatica (L.) Urban whole plants were obtained from National Institute of Crop Science (Suwon, Korea) and Chonnam National University (Gwangju, Korea), respectively. Agrobacterium rhizogenes R1000 strain was kindly provided by Dr. In (Nongwoo Bio, Yeju, Korea). Results and Discussion The role of farnesyl diphosphate synthase (FPS) in triterpene biosynthesis (Fig. 1) was investigated. A pCAMBIA3101 vector was used to insert a exogenous gene into target plant genome (Fig. 2). After the transformation, we produced Panax ginseng and Centella asiatica hairy roots by introducing the coding region of the gene from Panax ginseng. In these hairy roots, integration of the transgenes into the C. asiatica nuclear genome was confirmed by PCR analysis using PgFPS (P. ginseng FPS) primers and by Southern hybridization using PgFPS-specific probe. FPS specific activity is increased 4-fold compared to controls. In RT-PCR analysis, overexpression of PgFPS in hairy roots was observed (Fig. 3) and two genes, cycloartenol and beta-amyrin synthase, related to triterpene biosynthesis were up-regulated. These results suggest that FPS overexpression might lead to an enhanced biosynthesis of triterpene saponins and phytosterols. However, we did not demonstrate whether or not the introduction of PgFPS gene in Centella asiatica genome directly enhances triterpene saponin production, although our results showed that gene expression related to triterpene saponin biosynthesis were obviously up-regulated. Therefore, additional experiments such as overexpression of FPS gene in triterpene saponin-deficient mutant plants will be required.