• Korean Journal of Veterinary Research
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• v.37 no.3
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• pp.541-546
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• 1997

There are two conserved regions with a significantly high amino acid sequence homology among the A subunits of STX, SLTs and ricin. To produce an inactive Verotoxin-2 (VT-2), two different mutants, pE167D and pDE5A, were constructed by site-directed mutagenesis, respectively, on the basis of the previous reports that two regions lie within the active-site clefts of the A subunits of ricin and STX family. The cytotoxicity ($10^3$ $CD_{50}/ml$) of VT-2 holotoxin with E167D mutation was reduced by $10^3$-fold compared with wild-type level. In addition, VT-2 with DE5A ($Trp_{202}GlyArgIleSer_{206}$) deletion mutation showed a significantly low cytotoxicity ($10^1$ $CD_{50}/ml$), resulting in $10^5$- and $10^2$-fold reductions, respectively, compared with the wild-type and E167D mutatant. SDS-PAGE for protein samples showed a 33-kDa band corresponding to the A subunit of VT-2. These results indicate that reduction in cytotoxic activity was affected not by amount of VT-2 protein produced but by mutation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.10a
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• pp.146-148
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• 2010

최근 국제적으로 e-Navigation을 지향하는 해상안전에 대한 국제적 기술개발 및 표준화가 활발하게 진행되고 있다. 이러한 국제적 변화와 더불어 국내에서도 차세대 해상교통관제기술개발의 필요성이 제기되어 왔다. 즉, 차세대 VTS(Vessel Traffic management Service)는 e-Navigation의 육상 시스템으로의 역할을 수행하기 위한 새로운 개념과 서비스가 도입되어야 하며 기존 시스템과는 차별화될 수 있는 요인이다. 따라서 본 논문에서는 차세대 VTS인 u-VTS의 개념과 구조를 정립하고 관련 서비스 요구 사항을 고찰하고자 한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.54-56
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• 2011

국내에 구축된 VTS는 해상안전을 위한 세계적인 기술흐름을 따라가기 힘들고, 향후 e-Navigation을 구현하기 위한 신기술을 VTS 센터에 적용하기에는 많은 기술적 제약이 따르며, 새로운 개념을 제안하더라도 마땅히 시험할 기반이 없는 실정이다. 이에 e-Navigation이라는 국제적인 추세에 대응하고, 새로운 기술이 접목된 한국형 VTS를 개발하고자 "해양 안전 실현을 위한 차세대 VTS(u-VTS) 기술개발"이라는 연구를 진행하고 있다. 이번 연구에서는 국내의 해상교통환경에 적합하고, 효율적으로 운영할 수 있는 차세대 VTS 시스템에 적용될 운영소프트웨어의 기능을 연구했다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.761-766
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• 2008

This paper describes a compensation algorithm for a measurement voltage transformer (VT) based on the hysteresis characteristics of the core. The error of the VT is caused by the voltages across the primary and secondary windings. The latter depends on the secondary current whilst the former depends on the primary current, i.e. the sum of the exciting current and the secondary current. The proposed algorithm calculates the voltages across the primary and secondary windings and add them to the measured secondary voltage for compensation. To do this, the primary and secondary currents should be estimated. The secondary current is obtained directly from the secondary voltage and used to calculate the voltage across the secondary winding. For the primary current, in this paper, the exciting current is decomposed into the two currents, i.e. the core-loss current and the magnetizing current. The core-loss current is obtained by dividing the primary induced voltage by the core-loss resistance. The magnetizing current is obtained by inserting the flux into the flux-magnetizing current curve. The calculated voltages across the primary and secondary windings are added to the measured secondary current for compensation. The proposed compensation algorithm improves the error of the VT significantly.

• International Journal of Contents
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• v.14 no.2
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• pp.7-15
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• 2018

Online shopping is increasing worldwide. Providing customers actual feeling of the product is essential in online shopping. Various technological aids can be used to support visual feeling. When delivering visual tangibility, it is important to study which attributes are significant in product presentations that best portray the actual tactileness. In this perspective, we suggest 'visual tactility' (VT) as a parameter for delivering tangibility in visual presentation. By measuring visual tactility in different product types, latent factors of visual tactility were identified and their influence on purchase intention was determined in this study. We defined material properties of touch such as surface texture, hardness, temperature, and weight as Visual Tactility (VT), the influential factor of tactility. We investigated the influence of VT on product purchase intention and analyzed tactileness within four online product presentations: single static picture, multi static pictures, zoom, and video. Our purpose was to investigate underlying effects of visual tactile attributes on touch and determine their influences according to online product presentation formats. Our results showed that visual tactility positively affected purchase intention and that each attribute differed in importance according to product type. Moreover, this study revealed a strong relation between online product presentation and VT attributes. These results provide a guide when selecting which presentation is optimal for delivering a product's tactility in online shopping situation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.504-506
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• 2012

선박 운항 안전을 위한 기술은 선박 자체뿐만 아니라 육상 해상교통관제 시스템(VTS)에서도 매우 중요한 역할을 수행한다. 최근 국제적으로 e-Navigation을 지향한 최신 IT기술을 반영한 새로운 안전운행을 지원하기 위한 VTS 항행 지원 기술개발이 활발하게 진행되고 있다. 이러한 국제적 변화와 더불어 최근 국내외에서 AIS의 확장인 ASM을 통한 신규 서비스 제안이 활발하게 이루어지고 있으며, 해당 서비스를 시범서비스하고 이를 국제 표준으로 추진하고자 하는 업체와 IALA 등 해당 그룹들이 계속 증가되고 있다. 특히 국내에서는 VTS의 개발을 추진하고 있으므로 기존의 VTS에서 제공하지 않았던 ASM 서비스를 제안하고 이를 구현하여 시뮬레이션하여 가능성을 검증하고자 한다. 따라서 본 연구에서는 이러한 항행지원을 증가하는 e-Navigation 환경에서 국내 VTS 시스템에서 적용 가능한 방안을 연구하고, 이들을 비교하여 실제 적용할 수 있는 기술개발 방향을 정립하고자 한다.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.261-263
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• 2005

In the extra and ultra high voltage system, the coupling capacitor voltage transformer (CCVT) measures the primary voltage with a small scale of voltage transformer (VT). However, the CCVT generates errors caused by the hysteresis characteristics of iron core and by the ferroresonance, inevitably. This paper proposes a compensation algorithm for the secondary voltage of a CCVT considering the hysteresis characteristics of an iron core. The proposed algorithm calculates the seconda교 current of a VT by summing the current flowing the ferroresonance circuit and the burden current; it estimates the secondary voltage of a VT; then the core flux is calculated by integrating of the secondary voltage of a VT, then estimates the exciting current using ${\lambda}-i$ characteristic of the core. The method calculates a primary voltage of a VT considering the estimated primary current. Finally, the correct voltage is estimated by compensating the voltage across the inductor and capacitor. The performance of the proposed algorithm was tested in a 345kV transmission system. The test results show that the proposed method can improve the accuracy of the seconda교 voltage of a CCVT.

• Korean Journal of Veterinary Research
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• v.50 no.3
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• pp.231-237
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• 2010

This study was conducted to investigate characteristics and antimicrobial susceptibility of Escherichia (E.) coli isolates isolated from vaginal mucosa and clitorial fossa of 105 Thoroughbred mares suspicious of the genital disease in Korea during the period from March 2006 to July 2007. Ninety six E. coli isolates were identified as standard biochemical properties and using BIOLOG system. Fifty three isolates (55.2%) could be classified into a total of 21 O serotypes and forty three isolates (44.8%) were non-typeable with 51 O antisera used in this study. The verotoxin 1 (VT 1) and verotoxin 2 genes were analyzed by multiplex PCR. Among them, one isolate was detected VT 1 gene (130 bp). Most of isolates showed a high susceptibility in ciprofloxacin (100%), enrofloxacin (100%), norfloxacin (100%), cefoxitin (96.9%), gentamicin (96.9%), sulphamethoxazole (96.9%), nitrofurantoin (94.8%), amikacin (93.8%), nalidixic acid (92.7%) and tetracycline (90.6%). These results may provide the basic information to establish strategies for the treatment and prevention of reproductive disease in Thoroughbred mares in Korea.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.254-255
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• 2018

해상안전과 해양오염 방지를 위해서 해상교통관리체계의 안전관리를 위한 개선방안이 필요한 실정이다. 이 연구에서는 항만 VTS의 운영현황 및 성과분석, 설문조사 및 AHP기법을 이용해 미래지향적인 해상교통관리체계를 제시하였다.

• Korean Journal of Veterinary Research
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• v.36 no.2
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• pp.379-387
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• 1996

The objects of the present study were to establish the method of purification, subunit dissociation of verotoxin-2 (VT2) produced by Escherichia coli O157:H7, and to investigate the characteristics of purified verotoxin-2 such as molecular weight and composition of amino acid. The results were summerized as follows; Verotoxin-2 was extracted by addition of polymyxin B sulfate into bacterial cell lysate prepared from Escherichia coli O157:H7(KSC109). As an initial step, the bacterial cell lysate was precipitated with 30% saturated ammonium sulfate. The precipitated crude toxin was then subjected to anion-exchange, chromatofocusing and cation-exchange chromatography. Using this scheme, we obtained highly purified toxin with a specific activity of $1.1{\times}10^9$ $CD_{50}/mg$. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) for purified VT2 showed two protein bands. The upper band, approximately 32 Kd, was supposed as A subunit and the lower band, approximately 7.7 Kd, was supposed as B subunit. When the toxin was separated in the subunit-dissociating solution, two peaks emerged with retention times of 15 and 28 min by HPLC. These peaks represented A subunit and B subunit, respectively. The amino acid composition of purified VT2 were made up in order of glutamic acid, histamine, asparaginic acid, histidine, lysine, alanine and leucine etc. The largest amount among the amino acid composing VT2 was methionine.