• Journal of Korea Society of Industrial Information Systems
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• v.2 no.1
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• pp.103-123
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• 1997

This dissertation provides a theoretic study on the network security in general , the firewall in particular. In fact the firewall has been recognized as a very promising option to obtain the security inthe real work network environment . The dissertation provides a throuth theoretic investigation on the various problems raised in the computer network, and also explores a methodology of the security against IP spoofing. Moreover, it investigates a systematic procddure to make analysis and plans of the firewall configuration . Based on the above investigation and analysis, this dissertation provides two approaches to network security , which address anumber of issuesboth at the network and at applicatino level. At the network level, a new method is proposed which uses packet filtering based on the analysis of the counter plot about the screen router.On the other hand, at the application level, a novel method is explored which employs secureity software. Firewall-1 , on Bastion host. To demonstrate the feasibililty and the effectiveness of the proposed methodologties , a prototype implementation is made The experiment result shows that the screen router employing the proposed anti-IP spoofing method at the network level is effective enough for the system to remain secure without being invaded by any illegal packets entering form external hackers. Meanwhile , at the application level, the proposed software approach employing Firewall-1 is proved to be robust enugh to prevent hackings from the outer point the point protocal connnection . Theoretically, it is not possible to provide complete security to the network system, because the network security involve a number of issues raised form low level network equipments form high level network protocol. The result inthis dissertation provides a very promising solution to network security due to its high efficiency of the implementation and superb protectiveness from a variety of hacking.

• Management & Information Systems Review
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• v.28 no.4
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• pp.27-44
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• 2009

Economic value of a certain technology is of great interest and importance in a wide variety of investment circumstances. These vary from companies considering investing in R&D projects, to venture capitalists funding start-up companies. However, such valuation is extremely difficult in any case, and the cost of failure can be very high. Many techniques have been proposed to assist managers facing this issue, from traditional discounted cash flow analysis to more recent methods based on real options. In the meantime, the discounted cash flow method has limitations in applying the valuation of technology. At the same time, there have been various solutions to overcome theoretical problems of the method. Real options have been thought as a solution. However, there are another problems in using them in real world. This paper reviews the previous studies on the valuation of technology in several aspects, discusses the practicability of the various methods available, and explore the application of a hybrid model, which aims to make these rather aore the ideas more accessible to practicing managers.

• Journal of the Korean Data and Information Science Society
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• v.27 no.4
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• pp.979-991
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• 2016

Measuring nation images was a challenging task when employing offline surveys was the only option. It was not only prohibitively expensive, but too much time-consuming and therefore unfitted to this rapidly changing world. Although demands for monitoring real-time nation images were ever-increasing, an affordable and reliable solution to measure nation images has not been available up to this date. The researcher in this study developed a semi-automatic ontology construction algorithm, named "double-crossing double keyword collection (or DCDKC)" to measure nation images from Wikipedia in real-time. The ontology, WikiOnto, can be used to reflect dynamic image changes. In this study, an instance of WikiOnto was constructed by applying the algorithm to the big-three exporting countries in East Asia, Korea, Japan, and China. Then, the numbers of page views for words in the instance of WikiOnto were counted. A collection of the counting for each country was compared to each other to inspect the possibility to use for dynamic nation images. As for the conclusion, the result shows how the images of the three countries have changed for the period the study was performed. It confirms that DCDKC can very well be used for a real-time nation-image monitoring system.

• Management & Information Systems Review
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• v.7
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• pp.21-51
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• 2001

For increasing the competitiveness and efficiency of Korea's finance industry under the new e-finance paradigm, this paper compared the practical use of finance portal site' on service parts and stage between Korea and U.S.A.. The services which can be served from site are banking, mortgage and credit loan, stock, card, retirement tax, PFM(Personal Finance Management), EBPP(Electronic Bill Presentment and Payment) and Account Aggregation and so on. The stage of site can be divided as the information provide stage which only gives information about service parts, on-line transaction stage which real-time transaction is possibile and PFM services provide stage according to development process. As a result, the beginning of finance portal service in Korea was lated about 10years and more than it of U.S.A. So the development stage of domestic portal site is still staying in the first step and the providing services and contents or business model development parts are also in the same stage than U.S.A. Resides, Korea's sites mainly focus on their first service parts even though they recently aim internet finance portal, and provide not real time transaction but finance information. On the other hand, the U.S.A. site support substantially not only various on-line transactions but also distinctive personal services like PFM(Personal Finance Management), EBPP(Electronic Bill Presentment and Payment), Account Aggregation and Trans-account, brokerage, education center, mortgage loan, mutual fund, option, pension fund and IPOs and so on. Thus, the site of Korea need to establish real type of internet finance portal which provides one-stop services on every type of finance to customers in the real time and also require the strategic integration among finance institutions. The next turn, they need to build information system and education center to give best satisfaction to customers and acquire customer information and marker environment changes and need to provide distinctive services to quality customers throughout database from this. Also the site should provide various type of banking services which refereed above like PEM, EBPP and education center etc, and the government of Korea should support the building of IT infrastructure to Physical, legal, systematic, sociocultural, technical and human resource sections. This paper provided the future movement direction of the domestic finance portal through comparison and analysis on the practical use of it between Korea and U.S.A. and also wanted to contribute for developing and reading of Korea finance portal in the new era of the finance paradigm.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.611-619
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• 2017

This paper intends to develop unit water production cost (UWPC) between alternative water resources including desalination, freshwater reservoirs, single-purpose dams, underground dams, and two indirect water in-take technologies - riverbank filtration and aquifer storage and recovery (ASR). The UWPCs of water supply schemes including each alternative are determined based on project cost, and operation and maintenance estimation models, which were developed based on real project cost data. The sensitivity analysis of UWPCs reveals that ASR is the lowest cost option in producing drinkable water among the alternatives, followed by riverbank filtration and underground dam. It is expected that economics related to the finding plays a critical role in supporting water resources planning and budget allocation for central and local water authority in Korea.

• Environmental and Resource Economics Review
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• v.24 no.4
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• pp.607-627
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• 2015

As observed and experienced in EU ETS, allowance price volatility is one of major concerns in decision making process for $CO_2$ abatement investment. The problem of linearly non-separable profits functions could emerge when one power company holds several power plants with different technology specifications. Under this circumstance, conventional analytical solution for investment option is no longer available, thereby calling for the development of numerical analysis. This paper attempts to develop a Monte-Carlo least squares model to analyze investment options for power companies under emission trading scheme regulations. Stochastic allowance price is considered, and simulation is performed to verify model performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.168-175
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• 2020

Recently, there has been an increasing need to expand the supply of renewable energy as a solution to greenhouse gas emissions. Therefore, as a measure to promote domestic renewable energy investment and gradual expansion, this study analyzed the investment value of renewable energy projects utilizing the unoccupied spaces of public enterprise's facilities and presented a strategic decision-making framework to support efficient national land development and government measures. The NPV was estimated to be 286 million won if the expansion of the facility was not considered, but it is reasonable to postpone the expansion decision because the value of -130 million won was calculated if the expansion was considered. On the other hand, the real-option value was estimated to be 444 million won, taking SMP uncertainty, expansion, and abandonment options into account, and an additional value of 288 million won was calculated from an analysis of the expansion project using the existing NPV analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1634-1647
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• 2007

"To invest or not to invest?" Most business leaders are frequently faced with this question on new and ongoing projects. The challenge lies in deciding what projects to choose, expand, contract, defer, or abandon. The project valuation tools used in this process are vital to making the right decisions. Traditional tools such as discounted cash flow (DCF)/net present value (NPV) assume a "fixed" path ahead, but real world projects face uncertainties, forcing us to change the path often. Comparing to other traditional valuation methods, the real options approach captures the flexibility inherent to investment decisions. The use of real options has gained wide acceptance among practitioners in a number of several industries during the last few decades. Even though the options are present in all types of business decisions, it is still not considered as a proper method of valuation in some industries. Mining has been comparably slow to adopt new valuation techniques over the years. The reason fur this is not entirely clear. One possible reason is the level and types of risks in mining. Not only are these risks high, but they are also more numerous and involve natural risks compared with other industries. That is why the purpose of this study is to deal with a more practical approach to project valuation, known as real options analysis in mining industry. This paper provides a case study approach to the copper mining industry using a real options analysis. It shows how companies can minimize investment risks, exercise flexibility in decision making and maximize returns.

• Journal of Korean Physical Therapy Science
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• v.16 no.1
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• pp.31-39
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• 2009

Background: Community ambulation has been recently recognized as one of the most essential factors of activities of daily living in patients with post-stroke hemiparesis. This study aimed to compare walking velocity and step number in 5 community situations in patients with post-stroke hemiparesis. Methods: Ten chronic stroke patients volunteered for this study. The main variables analyzed were walking speed and step number, and these were measured in 5 different community situations: a physical therapy room, a parking lot, a bank, a crosswalk, and a hospital lobby. The measurements obtained for walking in the physical therapy room were measured using a 10m walk test and were used as baseline data for comparison with each option. The ambulation distance was set at 300m for the parking lot and the bank and 150m for the crosswalk and hospital lobby. For data analysis, walking speed and step number were standardized with the distance options of each ambulation. Results: Compared to the walking speed in the physical therapy room, those in the other situations, except for the parking lot, were significantly different (p<.05). Moreover, there were significant differences in the speeds between the bank and the parking lot and between the parking lot and the crosswalk (p<.05). Compared to the step number in the physical therapy room, those in all situations except for the crosswalk were significantly different (p<.05). Further, there was a significant difference in the step number between the bank and the crosswalk (p<.05). Conclusion: The walking ability of patients with hemiparesis in real environments within a community could be different from that in a physical therapy room. Therefore, the evaluation of walking should be performed in a variety of community situations.

• Imaging Science in Dentistry
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• v.39 no.3
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• pp.115-120
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• 2009

Purpose : The purpose of this study was to determine a conversion coefficient for Hounsfield Units(HU) to material density ($g\;cm^{-3}$) obtained from cone-beam computed tomography ($CBMercuRay^{TM}$) data and to measure the hard tissue density based on the Hounsfield scale on dental head phantom. Materials and Methods : CT Scanner Phantom (AAPM) equipped with CT Number Insert consists of five cylindrical pins of materials with different densities and teflon ring was scanned by using the $CBMercuRay^{TM}$ (Hitachi, Tokyo, Japan) volume scanner. The raw data were converted into DICOM format and the HU of different areas of CT number insert measured by using $CBWorks^{TM}$. Linear regression analysis and Student t-test were performed statistically. Results : There was no significant difference (P > 0.54) between real densities and measured densities. A linear regression was performed using the density, $\rho$($g\;cm^{-3}$), as the dependent variable in terms of the HU (H). The regression equation obtained was $\rho=0.00072H-0.01588$ with an $R^2$ value of 0.9968. Density values based on the Hounsfield scale was $1697.1{\pm}24.9\;HU$ in cortical bone, $526.5{\pm}44.4\;HU$ in trabecular bone, $2639.1{\pm}48.7\;HU$ in enamel, $1246.1{\pm}39.4\;HU$ in dentin of dental head phantom. Conclusion : CBCT provides an effective option for determination of material density expressed as Hounsfield Units.