• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.2
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• pp.303-310
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• 2018

Bitcoin (BTC) is a cryptocurrency proposed by Satoshi Nakamoto in 2009. Bitcoin makes its transactions with no central authorities. This decentralization is accomplished with its mining, which is an operation that makes people compete to solve math puzzles to include new transactions into block, and eventually block chains (ledger) of bitcoin. Because miners need to solve a complex puzzles, they need a lot of computing resources. In return for miners' resources, bitcoin network gives newly minted bitcoins as a reward to miners when they succeed in mining. To prevent inflation, the reward is halved every 4 years. For example, in 2009 block reward was 50 BTC, but today, the block reward is 12.5 BTC. On the other hands, exchange rate for bitcoin and Korean Won (KRW) changed drastically from 924,000 KRW/BTC (January 12th, 2017) to 16,103,306 KRW/BTC (December 10th, 2017), which made mining more attractive. However, there are no rigorous researches on the profitability of bitcoin mining. In this paper, we evaluate the profitability of bitcoin mining.

• The Journal of Engineering Geology
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• v.4 no.3
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• pp.321-331
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• 1994

Environmental geologic maps were produced on the cheong-Ju area using GIS technique. They are GIS maps on land management and regional land use planning. In the last year, the model of environmental geologic map was established, and the digital database was constructed by environmental and geotechnical data collected form various sources. The special maps for environmental geologic study were also pnoduced ; landslide hazard and risk map, cut & fill map, actual run-off map and engineering geological map. The maps are secondary models (sub-model) in order to create final environmental geologic map. Finally, Environmental Geologic Unit(EGU) was evaluated for regional land use planning and land management by EGIS(Environmental Geologic Inforafion System). This unit is very important in order to assess environmental geologic impact on large construction works and detailed road design etc.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.4
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• pp.818-823
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• 2009

Web is greatly contributing in providing a variety of information. Especially, as media for the purpose of development and education of human resources, the role of web is important. Furthermore, E-Learning through web plays an important role for each enterprise and an educational institution. Also, above all, fast and various searches are required in order to manage and search a great number of educational contents in web. Therefore, most of present information is composed in HTML, so there are lots of restrictions. As a solution to such restriction, XML a standard of Web document, and its various search functions is being extended and studied variously. Moreover, any technology, AJAX, and the old and new technology has two sides. The technology already exists, and it was not even considered before, because new technology is combined technologies. AJAX is a lot of Web 2.0 and Web technologies complement are combined. This paper proposes a search system able to search XML, AJAX in E-Learning or various contents of non-XML.

• The Journal of Korean Association of Computer Education
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• v.13 no.5
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• pp.103-110
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• 2010

If an exterior computer wants to join the Grid/cloud computing platform for a while, all of the related firewalls' filtering rule should be immediately updated. As the platform of Internet application is gradually evolving into the Grid/Cloud environment, the R&D requirement for the dynamic traversing of the multiple firewalls by a single try is also increasing. In this paper, we introduce the new mechanism for the dynamic traversing of the multiple firewalls using the concept of the one-time master key that can dynamically unlock the tiers of firewalls simultaneously instead of the existed filtering rule based method like a lock management at each firewall. The proposed master keys are like one-time password, consisted of IP addresses, port numbers, and TCP's initial sequence numbers, and generated by end users not administrators. They're exchanged mutually in advance and used to make a hole at local-side firewalls for the other's packet incoming. Therefore, the proposed mechanism can function regardless of the number or type of firewalls.

• Survey Research
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• v.10 no.3
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• pp.107-130
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• 2009

This study examines the factors affecting Korean firms' adoption of maternity protection practices. From a neo-institutional perspective, we argue that firms adopt institutionally legitimized practices mainly for their legitimacy concern rather than technical efficiency. Analysis of data from Establishment panel survey reveals that firms which belong to public sector, has received foreign investment, bench-mark leading firms, or have HR department are more actively adopting maternity protection practices and are showing lower level of decoupling between model and reality. These results imply that legitimacy concern matters among Korean firms in terms of adopting maternity protection practices. We propose that it is important for government agencies to take institutional factors into account when they try to promote maternity protection policy among firms in dealing with the problems of low fertility and gender equity.

• Fire Science and Engineering
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• v.26 no.2
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• pp.17-31
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• 2012

Regarding the landslide that took place around 00:08 on July 27, 2011, in a village in the city of Chuncheon (Sanjidanggol, Majeoksan, Cheonjeon-ri, Sinbuk-eup, Chuncheon-city, Gangwon-province), this paper surveyed fire-fighting officers who were injected into the site to rescue the disaster, thereby determining the problems surrounding the initial fire-fighting response and improvement measures. As a result, specialist education of volunteer fire-fighters and utilization, improvement measures included the early response ability enhancement of and cooperation between relevant agencies, the strengthening of specialist education about landslide response, the strengthening of situation management and field command system, the installation and operation of speedy field emergency infirmary, the operation of an appropriate volunteer waiting facility, the operation of an appropriate control lines, appropriate control of media, a sufficient securing of individuals' rescue equipment and fuel for heavy equipment, the provision of sufficient portable radios and chargers, the securing of fire-fighting budget thereof.

• Journal of Information Management
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• v.39 no.4
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• pp.21-46
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• 2008

The Result of this study (1)In the case of KDI school of public policy and management, since it makes up a very interesting and diversified racial environment that shapes the multinational global community, there must be careful considerations for foreign students together with wide publicity about Korea on the side of the school headquarters. (2)The library must become familiar with the ways to utilize outside organizations in order to provide user education to the foreign students. (3)In order to make it perfectly sure for them to provide not only the secondary materials such as bibliography, index, and abstract, but also the necessary full-text from the preparatory stage of the students' studies. (4)The library must grasp the students' needs through communication and must promote the efficiency of library operation by introducing an information service strategy measure similar to that of FISP so they can acknowledge and provide necessary information to fulfill the students' academic needs in advance.

• Journal of Information Management
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• v.38 no.1
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• pp.141-160
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• 2007

Many contents produced and provided as development of information technology on the internet. Especially discussion that collecting and storing of digital information resources, is expanded as growing dependence on academic information of research workers. Open Access is a new paradigm of information distribution that is opposite concept of high price distribution academic information. It is an OAI system that is intended to collect and automate open access data in good order. This paper constructs stOAI based on OAI that is a science and technology information providing system. This system provides international academic journal free of charge that collect and store through OAI protocol in OA(Open Access) of yesKISTI(science and technology information portal service). Also, It provides automate and centralize science technology information, that KISTI has, to external institution as a standard type.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.8
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• pp.524-535
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• 2006

With rapid development of Internet technology, business management in an organization or an enterprise depends on Internet-based technology for the most part. Furthermore, as dependency and cohesiveness of network in the communication facilities are increasing, cyber attacks have been increased against vulnerable resource in the information system. Hence, to protect private information and computer resource, research for damage propagation is required in this situation. However the proposed traditional models present just mechanism for risk management, or are able to be applied to the specified threats such as virus or worm. Therefore, we propose the probabilistic model of damage propagation based on the Markov process, which can be applied to diverse threats in the information systems. Using the proposed model in this paper, we can predict the occurrence probability and occurrence frequency for each threats in the entire system.

• The Journal of the Korea Contents Association
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• v.13 no.7
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• pp.301-310
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• 2013

The purpose of this study was to investigate and compare the risk factors of cognitive impairment between non-depressive elderly and depressive elderly. Data was obtained from 1,477 elderly not diagnosed to dementia. In result, non-depressive elderly group was found as having risk factors of cognitive function in age and educational level. In non-depressive group, older elderly(OR=1.095) and the elderly with no experience of education(OR=9.129) had more in risk of cognitive impairment. Depressive elderly group was found as having risk in age, educational level, and residence style. In depressive elderly, older elderly (OR=1.101), the person with low education(illiteracy:OR=33.020, elementary:OR=10.176, middle school: OR=9.841), and the elderly living in nursing home(OR=8.490) had more in risk of cognitive impairment. Through this result, it could be suggested that the depressive elderly with low educational level living in nursing home should be intervened to decrease the rate of dementia more effectively.