• Journal of KIISE:Information Networking
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• v.33 no.6
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• pp.407-419
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• 2006

As substituting IPv6 network for all IPv4 network in a short time seems unattainable due to high cost and technical limitation, IPv4 and IPv6 are expected to coexist for a certain period of time. Under the co]existing environment of IPv4 and IPv6, interworking brings a number of extra security considerations even if it may have no security problem for each protocol respectively. Thus, the analysis and solutions for those various attacks toward IPv4/IPv6 interworking-related security are inevitably required for the sake of effective transition and settlement to IPv6. In this paper we carried out a proper rule of packet filtering for IPv6-in-IPv4 tunneling interworking environment to protect the IPv4/IPv6 interworking-related security attacks. Design and implementation of the packet filtering system suitable for IPv4/IPv6 tunneling environment in the form of Linux netfilter and ip6tables are also shown. Thru this study, the packet filtering system was found operating correctly ill the tunneling mechanism.

• Journal of Service Research and Studies
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• v.6 no.3
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• pp.29-40
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• 2016

Since the late 20th century, there has been much effort to improve the market value of media contents which are commercialized in a digital format, by fusing digital data of video, audio, numerals, characters with IT technology together. Then by what criteria and methodologies could the market value for the drama "Sons of the Sun" or the animated film 'Frozen', often referred to in the meida, be estimated? In the circumstances there has been little or no research on the valuation framework of media contents and the status of their valuation system development to date, we propose a practical valuation models for various purposes such as contents trading, review of investment adequacy, etc., by formalizing and presenting a contents valuation framework for the four types of media of movies, online games, and broadcasting commercials, and animations. Therefore, we develope computational methods of cash flows which includes production cost by media content types, provide reference databases associated with key variables of valuation (economic life cycle, discount rates, contents contribution and royalty rates), and finally propose the valuation framework of media contents based on both income approach and relief-from-royalty method which has been applied to valuation of intangible assets so far.

• Journal of Adhesion and Interface
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• v.12 no.3
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• pp.99-104
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• 2011

Currently, automotive pre-primed coatings has been developed to overcome environmental regulations and to reduce manufacturing cost in automotive industry. By these reasons, an automotive pre-primed system has been investigated to remove the wash and pre-treatment process using a roll coating application. It is required to develop non-weldable pre-primed system for automotive structural adhesives, because pre-primed sheet coated with organic compounds is hard to be assembled by welding process. Primer 1 (polyester type) and primer 2 (urethane type) were designed to satisfy flexibility and formability for non-weldable pre-primed system. According to the results of physical property test of the primers, adhesion test such as single-lap shear test and T-peel test, primer 1 (polyester type) had better physical properties such as pencil hardness, solvent resistance, flexibility and adhesion with automotive adhesive than that of primer 2 (polyurethane type). In addition, the possibility of the non-weldable pre-primed system was applicable to automotive assembly process in place of welding process.

• Environmental and Resource Economics Review
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• v.30 no.3
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• pp.395-433
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• 2021

This paper aims to examine the effects of homeownership and residential types on the economic values of urban green spaces. Green open spaces as public goods provide positive externalities that are comprised of pecuniary and technological externalities. Seoul, South Korea, is used as a case study using choice experiments, with split-sample online respondents of 1,000. The study results evidenced that the differentiation between the two types of externalities is imperative for equitable provisions and efficient management of various urban open spaces. There is a positively significant and substantial impact of homeownership for apartment dwellers, ceteris paribus, but not for house dwellers. For apartments, the efficiency loss can be reduced by increasing green spaces up to the critical point where the marginal cost is at equilibrium with tenants' marginal values. For non-apartment houses, it is not homeownership but the monthly household income that has a significant impact on the amenity value. In general, public benefits from green spaces are equivalent to 16% to 33% of the current residential prices on average for a view or access. Different residential types do not cause a significant impact on the access values. Residential profiles for green spaces were developed, together with tailor-made policy suggestions.

• Korean Journal of Construction Engineering and Management
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• v.22 no.3
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• pp.79-90
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• 2021

In domestic public construction, disputes are increasing due to differences among stakeholders regarding contract price adjustment. In particular, the actual cost-plus fee for overhead costs due to the schedule extension cannot be agreed upon at the administrative phase, and most of them seek judicial judgment. Thus, this study aims to propose a 'sufficiently satisfactory' alternative to reach an agreement before disputes in order to minimize disputes related to the calculation of additional overhead costs. To this end, this study proposes three alternatives based on the rate method. Firstly, when calculating additional overhead costs, it is not calculated as an actual cost-plus-fee method, but as a rate compared to direct labor costs among net direct costs. Secondly, the calculated indirect labor costs are compensated for up to the legal maximum of legal limit costs such as general management costs, profits and so on. Thirdly, it reflects overhead costs increased or decreased due to change orders. Risks were analyzed by collecting expert opinions on the proposed methods and applying actual cases. Finally, as a result of investigating the level of consensus for each stakeholder, it was confirmed that all stakeholders could agree regardless of the size of the company. The result of this study is expected to as a useful tool among stakeholders in the construction fields that can be able to easily agreed upon.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.918-925
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• 2017

Multiple reflections on exterior equipment with complex shape on naval ships cause unexpectedly high Radar Cross Section (RCS) distributions, and the directions of reradiated electromagnetic waves are hard to predict. Therefore, the optimum arrangement of exterior equipments should be considered according to the Radar Absorbing Structure (RAS) method. In this paper, the optimum arrangement for exterior equipments was determined to reduce multiple reflections and RCS even with complex shapes. The sequential descending arrangement method was used to establish an optimum arrangement algorithm. An LCS-2 type model was selected for optimum exterior equipment arrangements. In order to reduce computational cost, RCS distributions and multiple reflection path analysis of exterior equipments was carried out to select exterior equipments for optimum arrangement, and an optimum arrangement was determined to find positions with minimum RCS values. Also, the RCS reduction effect was analyzed using detectable radar range.

• The Journal of the Korea Contents Association
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• v.19 no.9
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• pp.271-279
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• 2019

The life expectancy of people has been steadily extended due to the improvement of living standards and the development of medical technology. Besides, the low birth rate and long life expectancy decrease the youth population while the elderly population is steadily increasing. Many elderly people have enough time and financial allowance, and the interest in health care is increased all over society. There are also increasing numbers of elderly people who exercise lightly in the playgrounds and parks such as running and walking. Outdoor fitness equipment that can be easily seen in neighbourhood parks, public spaces, etc. can be good health promotion tools that can be easily accessed in the daily life of the elderly. Outdoor fitness equipment Description Signs require a design that takes into account the declining vision of older users. Proper design is also important for the prevention of safety accidents in use. The purpose of this study is to find out the perception of the elderly about outdoor fitness exercise equipment sign system and to find the problem of recognition. To do this, we conduct user observation and interview surveys for the elderly. As a result, the emphasis of the caveat or problems with the size of the writing were pointed out, and it was necessary to explain the picture rather than the text. Also, there was a high demand for refraining from using foreign words, using universal words and including motor effects in signs. Based on the results of the user observation and interviews, we propose guidelines for the use of outdoor exercise equipment.

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.277-285
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• 2011

Polysulfone (PSf) membranes were prepared via the phase inversion process. Polyvinylpyrrolidone (PVP) was added as a nonsolvent additive in the casting solution containing a mixture of PSf and n-methylpyrrolidone. The added PVP played a role of enhancing liquid-liquid phase separation of the casting solution, and significantly reduced the solution fluidity. When prepared via the diffusion-induced process using water as a precipitation nonsolvent, the solidified membranes revealed a typical asymmetric structure irrespective of the addition of PVP. With 5 wt% PVP content, the finger-like cavities were more developed in the membrane sublayer compared to that of the membranes prepared without PVP. In contrast, with more than 10 wt% of PVP, the formation of finger-like cavities was suppressed, and the thickness of polymer nodule layer was increased. The surface porosity was also increased with the PSf content in the casting solution. The water permeability curve as a function of PVP addition revealed the inflection point. The maximum water permeability for 12 wt% PSf membrane was obtained with 5 wt% PVP content, and that for 18 wt% PSf membrane with 15 wt% PVP.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.3
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• pp.305-316
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• 2021

Construction accidents occur due to a number of reasons-worker carelessness, non-adoption of safety equipment, and failure to comply with safety rules are some examples. Because much construction work is done outdoors, weather conditions can also be a factor in accidents. Past construction accident data are useful for accident prevention, but since construction accident data are often in a text format consisting of natural language, extracting construction hazards from construction accident data can take a lot of time and that entails extra cost. Therefore, in this study, we extracted construction hazards from 2,026 domestic construction accident reports using text mining and performed a seasonal analysis of construction hazards through frequency analysis and centrality analysis. Of the 254 construction hazards defined by Korea's Ministry of Land, Infrastructure, and Transport, we extracted 51 risk factors from the construction accident data. The results showed that a significant hazard was "Formwork" in spring and autumn, "Scaffold" in summer, and "Crane" in winter. The proposed method would enable construction safety managers to prepare better safety measures against outdoor construction accidents according to weather, season, and climate.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.7
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• pp.830-837
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• 2020

With the rapid development of information and communication technology, information exchange between ships and shore has become faster and more convenient, However, accessing ship information has also become easier and concerns about cyber security attacks are growing. When a ship suffers a cyber-attack, it may cause considerable damage and incurs enormous costs and time to repair. In response to this threat, the maritime industry now demands that a cyber security officer be assigned to each ship to take charge of cyber security management onboard. In order to reduce the damage cause by an attack and to respond effectively, a specialized training course for the ship's cyber security officer is required. The purpose of this study was to present a training course for the position of the ship's cyber security officer, and to highlight the necessity of amending current legislation, To this end, domestic and foreign trends, ship cyber security incident cases, and cyber security training courses were investigated, and based on the results a standard training course for a ship's cyber security of icer was developed. Additionally, recommendations on the related amendments to legislation ware established. The results of the study can be used as basic data to establish future training courses for cyber security officers.