• Title, Summary, Keyword: Block Chain

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A Comparative Study of Block Chain : Bitcoin·Namecoin·MediBloc (블록체인 비교연구: 비트코인·네임코인·메디블록)

  • Kim, Ji Yeon
    • Journal of Science and Technology Studies
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    • v.18 no.3
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    • pp.217-255
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    • 2018
  • Bitcoin, which appeared in 2008, was merely a conceptual virtual currency, but it now enjoys the status as actual money. Bitcoin is an electronic money system that can be traded directly without a central trust institution. Thanks to the popularization of Bitcoin, blockchain technology has become a widespread concern. That technology is expanding not only the currency mechanism, but also a variety of other services. The possibility of a blockchain in relation to actual currency is ongoing. This paper investigates the technological characteristics and social construction of the blockchain by comparing the cases of Bitcoin, Namecoin, and MediBloc among blockchain applications. Namecoin emerged in 2013 is an attempt to replace the centralized Internet Domain Name System(DNS). There has been controversy over that current system for a long time, but replacing the already established system is not easy. Nevertheless, Namecoin has potential as an alternative. Meanwhile, MediBloc is an application that involves distributed management of medical data in South Korea. MediBloc claims that the key producers of medical data are patients themselves. This is to challenge to the question who is a knowledge producer of medical data. Through these three cases, it has discussed that blockchain technology does supports to form more democratic decision-making or simply provide a technical solution as automation. As a citizen, we can intervene in the realization of blockchains by presenting social agenda. This will be a method of the social construction of technology.

Evaluating Blockchain Research Trend using Bibliometrics-based Network Analysis (블록체인 분야의 학술연구 동향분석: 계량정보학적 네트워크분석을 중심으로)

  • Zhu, Yu-Peng;Park, Han-Woo
    • Journal of Digital Convergence
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    • v.17 no.6
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    • pp.219-227
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    • 2019
  • This study aims to examine Blockchain research trend using bibliometrics-based network analysis. The data were collected from WoS, Scopus, Korea Citation Index and National science & Technology Information Service, from 2009 to 2018. As results, the number of publications has started increasing rapidly from 2017 and it showed the initial stage of formation of coauthor network. Words often used in the title of the publications were related to application development, controversy and technology development. In addition, the majority of domestic papers are in the subject of social science, while international papers tend to focus on engineering issues. The results of the temporal analysis show that Korean researchers' block chain 3.0 started in 2017 and are rapidly increasing in 2018. The number of citations was associated with publication year in a statistically signifiant way. By examining these research trends, we hope that this paper can be a useful basis for the development of blockchain. Future research is expected to reveal more clearly the knowledge structure and characteristics of blockchain around the world.

A Study on the Connective Validity of Technology Maturity and Industry for Core Technologies based on 4th Industrial Revolution (4차 산업혁명 기반 핵심기술에 대한 기술성숙도와 산업과 연계 타당성 연구)

  • Cho, Han-Jin;Jeong, Kyuman
    • Journal of the Korea Convergence Society
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    • v.10 no.3
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    • pp.49-57
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    • 2019
  • The core technology development of the Fourth Industrial Revolution is linked to the development of other core technologies, which will change the industrial structure in the future and create a new smart business model. In this paper, tried to analyze the technology maturity level and analyze the technology maturity. To do this, used technology trend information to investigate and integrate the market, policy, etc. Of core technology of the 4th Industrial Revolution to achieve a comprehensive maturity level. Because technology maturity measures are scored by technology developers, prejudices may be acted upon according to a person's tendency, which may be a subjective evaluation. It is also a measure of the maturity of individual technologies, and thus is not suitable for evaluating the overall system integration perspective. However, it is possible to evaluate the maturity before integrating the core element technologies constituting the whole system and to use it as a means to compare the effect of the whole system and its feasibility and play an important role in the planning of technology development.

Homoepitaxial Growth Mode of $Si(5\;5\;12)-2\times1$ Confirmed by Scanning Tunneling Microscope (STH) (주사터널링현미경(STM) 기법으로 확인된 $Si(5\;5\;12)-2\times1$ 호모에피텍시 성장 방법)

  • Kim Hidong;Cho Yumi;Seo Jae M.
    • Journal of the Korean Vacuum Society
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    • v.15 no.1
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    • pp.37-44
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    • 2006
  • The homoepitaxy of Si(5 5 12) at $495^{\circ}C$ has been studied by Scanning Tunneling Microscopy under ultrahigh vacuum. A Si-dimer is the basic building-block and preferentially adsorbs on a unique site, that is, the Si-dimer/adatom site at the (337) and the (225) subsections within the Si(5 5 12) unit cell. The Si(5 5 12) unit cell is faceted to $3\times(337)$ subsections filled with Si-addimers and $1\times(113)$ subsection. In this step the tetramer at the other (337) section within the unit cell is transformed to a dimer/adatom site which can accept Si-dimers. Each (337) section is faceted to $1\times(112)\;and\;1\times(113)$, and then finally the unit cell of Si(5 5 12) is faceted to $3\tiems(112)\;and\;4\times(113)$ and forms the facet of effective height, $2.34{\AA}$. In this step, mutual transformation between the honeycomb chain and the dimer/adatom occurs. Finally, the valley between (112) and (113) facets is filled. If once the last step is completed, the uniform and planar Si(5 5 12) terrace is recovered. From the present study, therefore, it can be concluded that the homoepitaxy on Si(5 5 12) is periodically achieved and such growth mode is quite unique since faceting of the substrate-unit-cell plays a critical role for controlling uniformity of the overlayer.

Limited Sympathetic Nervelipping of T2 Sympathetic Chain Block for Essential Hyperhidrosis (다한증의 제한적 교감신경절단술)

  • 박만실;서충헌;심재천;최봉춘;이영철
    • The Korean Journal of Thoracic and Cardiovascular Surgery
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    • v.32 no.9
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    • pp.813-817
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    • 1999
  • Background: Conventional thoracoscopic thoracic sympathectomy or sympathicotomy is an effective method in treating localized hyperhidrosis; however, this may result in a postoperatively embarrassing compensatory hyperhidrosis or facial anhidrosis in the treatment of palmar hyperhidrosis. We modified the conventional sympathicotomy by limiting the extent of nerve transection. The purpose of this study was to assess the result of the limited thoracoscopic sympathetic nerve transection in hyperhidrosis. Material and Method: From May to August 1998, 17 patients underwent limited transection of the sympathetic nerve. For 9 patients with facial hyperhidrosis, we transected only the interganglionic fiber between the first and the second ganglion, whereas the conventional method cuts two interganglionic fibers. Eight patients with palmar hyperhidrosis underwent limited transection of the interganglionic fiber between the second and third ganglion. Result: Sixteen patients had improved symptom postoperatively. There was a recurred facial sweating in 1 patient 1 month after the operation. Among the 9 facial hyperhidrosis patients, postoperative compensatory hyperhidrosis was severe in 4, moderate in 4 and minimal in 1. But in 8 cases of palmar hyperhidrosis compensatory hyperhidrosis was moderate in 3, and minimal in 1, none in 4. Facial sweating was not disturbed postoperatively in all of the palmar hyperhidrosis patients. Conclusion: Limited sympathetic nerve transection is a practical and less invasive method for the treatment of localized hyperhidrosis and may reduce the incidence of compensatory truncal hyperhidrosis and facial anhidrosis in case of palmar hyperhidrosis.

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Dietary Supplementation with Acanthopanax senticosus Extract Modulates Gut Microflora in Weaned Piglets

  • Yin, Fugui;Yin, Yulong;Kong, Xiangfeng;Liu, Yulan;He, Qinghua;Li, Tiejun;Huang, Ruilin;Hou, Yongqing;Shu, Xugang;Tan, Liangxi;Chen, Lixiang;Gong, Jianhua;Kim, Sung Woo;Wu, Guoyao
    • Asian-Australasian Journal of Animal Sciences
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    • v.21 no.9
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    • pp.1330-1338
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    • 2008
  • This study was conducted to investigate the effects of Acanthopanax senticosus extract (ASE) as a dietary additive on gut microflora in weaned piglets. A total of sixty pigs were weaned at 21 d of age (BW = $5.64{\pm}0.23kg$) and allocated on the basis of BW and litter to three dietary treatments in a randomized complete block design. The dietary treatments were: control group (basal diet), antibiotics group (basal diet+0.02% colistin), and ASE group (basal diet+0.1% ASE). On d 7, 14 and 28 after consuming the experimental diets, five piglets per group were sacrificed and then the contents from the jejunum, ileum and cecum were collected to determine changes in the microbial community by using a polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique and estimating the contents of Lactobacillus and E. coli by in vitro culturing methods. The results showed that the ASE promoted the microflora diversity in the cecum. Enumeration of bacteria in the gut contents showed that the number of Lactobacillus increased (p<0.05), while that of E. coli decreased (p<0.05) when compared with the other 2 groups as the days of age progressed post-weaning. These findings suggested that the ASE, as a substitute for dietary antimicrobial products, could improve the development of the normal gut microflora and suppress bacterial pathogens, and effectively promote a healthy intestinal environment.

Channeling of Intermediates Derived from Medium-Chain Fatty Acids and De novo-SYnthesized Fatty Acids to Polyhydroxyalkanoic Acid by 2-Bromooctanoic Acid in Pseudomonas fluorescens BM07

  • LEE, HO-JOO;RHO, JONG-KOOK;KAMBIZ AKBARI NOGHABI,;LEE, SEUNG-EUN;CHOI, MUN-HWAN;YOON, SUNG-CHUL
    • Journal of Microbiology and Biotechnology
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    • v.14 no.6
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    • pp.1256-1266
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    • 2004
  • 2-Bromooctanoic acid (2-BrOA) is known to block the formation of polyhydroxyalkanoic acid (PHA) in Pseudomonasfluorescens BM07 without any influence on the cell growth when grown on fructose, but it inhibits the cell growth when grown on octanoate (OA) (Lee et al., Appl. Environ. Microbiol. 67: 4963- 4974, 2001). We investigated the role of 2-BrOA in the PHA synthesis of the bacterium grown with mixtures of fructose and fatty acids. OA, 11­phenoxyundecanoic acid (1 1-POU), and 5-phenylvaleric acid (5-PV) were selected as model substrates. When supplemented with 50 mM fructose, all these carboxylic acids suppressed the formation of PHA from fructose, however, the ~-oxidation coenzyme A monomers derived from the carboxylic acids were efficiently polymerized, but the conversion yield [(mol of carboxylate substrate converted into PHA)/(mol of carboxylate substrate in the feed)] was low (e.g., maximally $\~53\%$ for 5 mM 11-POU). Addition of 2-BrOA (up to 5 mM) to the mixed carbon sources raised the conversion yield sensitively and effectively only at low levels of the acid substrates (e.g., 2 mM 1 1-POU or 5 mM OA): For instance, $100\%$ of 2 mM ll-POU were converted into PHA in the presence of 5 mM 2-BrOA, whereas only $\~10\%$ of the 1 1-POU were converted in the absence of 2-BrOA. However, at highly saturated suppressing levels (e.g., 5 mM ll-POU), 2-BrOA inhibitor showed no significant additional effect on the conversion ($60- 70\%$ conversion irrespective of 2-BrOA level). The existence of competitive and compensative relationship between 2­BrOA and all the carboxylic acid substrates used may indicate 'Present address: Section on Brain Physiology and Metabolism, Bldg. 10, Rm. 6N202, National Institute on Agmg, National Institute of Health, Bethesda, MD 20892, U.S.A. that all the acid substrate-derived inhibiting species bind to the same site as the 2-BrOA inhibiting species does. We, therefore, suggest that 2-BrOA can be used for efficiently increasing the yield of conversion of expensive substituted fatty acids into PHA and then substituted 3-hydroxyacids by hydrolyzing it.

The Study on the SEP (Standard Essential Patents) Procurement Strategy to accelerate the Trade Negotiation Competitiveness (통상 협상의 경쟁력 강화를 위한 표준특허 확보전략 연구)

  • Cho, Dongmin;Cho, Wongil
    • International Commerce and Information Review
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    • v.18 no.4
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    • pp.263-281
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    • 2016
  • The Importance of SEP (Standard Essential Patents) Procurement Operation is on the side of Governmental and Public both to accelerate the national trade negotiation competitiveness. To operate cooperative system of SEP creation and management, Government should monitor the effect and performance periodically to public sectors. and To achieve the support objectives, it should establish the virtuous circle infrastructure between R&D and economic performance on SEP. This can make the SEP enhancement to pursue the international competitiveness on Intellectual Property Rights. Especially the specific support approach to each phase of the SEP declaration matrix is essential to consolidate the possibility of SEP creation and acquisition. In this study, the concepts of SEP to accelerate the national trade negotiation competitiveness and the prior research were verified through the investigation of market trend and current state of affair analysis. Through the analysis of international and domestic situation of SEP procurement and management, We have found the results as follows. First of all, the leading conglomerates and the Government should focus on the secondary and tertiary industries to create and acquire SEPs to accomplish the effectiveness of selection and concentration. In second, the SMEs and Univ. Labs should focus on the quaternary sector of the economy to retain the competitiveness of speed and challenge on SEP related. From this study, the appropriateness of the tailored-support management model should be institutionalized, and the results implied an research in order to examine the suitability among the current SEP to enhance the competitiveness of national trade research issues.

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User Integrated Authentication System using EID in Blockchain Environment (블록체인 환경에서 EID를 이용한 사용자 통합 인증 시스템)

  • Kim, Jai-Yong;Jung, Yong-Hoon;Jun, Moon-Seog;Lee, Sang-Beon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.3
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    • pp.24-31
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    • 2020
  • Centralized systems in computing environments have various problems, such as privacy infringement due to hacking, and the possibility of privacy violations in case of system failure. Blockchain, one of the core technologies for the next generation of converged information, is expected to be an alternative to the existing centralized system, which has had various problems. This paper proposes a blockchain-based user authentication system that can identify users using EID in an online environment. Existing identification (ID)/password (PW) authentication methods require users to store personal information in multiple sites, and receive and use their respective IDs. However, the proposed system can be used without users signing up at various sites after the issuing of an EID. The proposed system issues an EID with a minimum of information, such as an e-mail address and a telephone number. By comparing the stability and efficiency of a centralized system, the proposed integrated authentication system proved to be excellent. In order to compare stability against existing systems, we chose attack methods and encroachments on the computing environment. To verify efficiency, the total throughput between the user's app, the issuance and certification-authority's servers, and the service provider's servers was compared and analyzed based on processing time per transaction.

Twenty-year Experience of Mitral Valve Replacement with the St. Jude Medical Mechanical Valve Prosthesis (St. Jude 기계 판막을 이용한 승모판막 치환술의 20년 장기성적)

  • Seo Yeon-Ho;Kim Kong-Soo;Jo Jung-Ku
    • The Korean Journal of Thoracic and Cardiovascular Surgery
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    • v.39 no.7
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    • pp.527-533
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    • 2006
  • Background: A retrospective study was conducted to analyze the results of St. Jude Medical mitral valve replacement at the Chonbuk National University Hospital since the initial implant in May 1984. Material and Method: Between May of 1984 and December of 1996, 95 patients underwent MVR with the St. Jude Medical mechanical valve prosthesis at Department of Medical Science of Chonbuk National University Hospital and follow-up ended in May of 2004. Result: Age ranged from 19 to 69 years. Follow-up (mean${\pm}$standard deviation) averaged $10.6{\pm}4.2\;year$. Thirty-day operative mortality was 4.2% (4/95). Nine late deaths have occurred and actuarial survival was $90.5{\pm}3.0%,\;87.9{\pm}3.4%\;and\;83.2{\pm}4.6%$ at 5, 10 and 20 years, respectively. Probability of freedom from valve-rotated death was $95.5{\pm}2.1%,\;94.3{\pm}2.4%\;and\;91.0{\pm}3.9%$ at 5, 10 and 20 years, respectively. Seven patients have sustained thromboembolic events (1,05%/patient-year). Fifteen patients had anticoagulation related hemorrhage (3.56%/patient-year). There was no structural valve deterioration. Probability of freedom from all complications was $82.0{\pm}3.9%,\;71.3{\pm}4.8%\;and\;42.4{\pm}10.5%$ at 5, 10 and 20 years, respectively. Conclusion: We confirm the effective and excellent durability of the St. Jude Medical prosthesis in the mitral position with a low event rate at long-term follow-up. It also demonstrates the commonly encountered practical difficulty of adjusting the anti-coagulation protocol in patients with prosthetic mitral valves.