• Journal of Korea Society of Industrial Information Systems
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• v.12 no.3
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• pp.47-59
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• 2007

IPv4 NAT, which often used in households or under SOHO environments, is one of the factors that delays IPv6 propagation. As IPv4 NAT does not operate properly under the transition mechanism like ISATAP or 6to4 that acts as IPv6-in-IPv4 tunneling type, Microsoft proposed Teredo in order to resolve this issue. However, tunneling transition mechanism like Teredo has a security problem. That is, being tunneled packets have dual IP headers; general firewall systems apply the filtering rules only to the outer header but not inner header when these packets pass the firewall. Furthermore, attacks using unregistered server and relay can take place in Teredo. To resolve these problems, we propose a new packet filtering mechanism exclusively for Teredo. The proposed packet filtering mechanism was designed and implemented by using Linux Netfilter and ip6tables. Through functional and experimental performance tests, this packet filtering system was found operating properly and solving the Teredo packet filtering problems without serious performance degradation.

• Journal of the Korean Society for Library and Information Science
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• v.51 no.2
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• pp.255-279
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• 2017

In a qualitative approach, this study investigated users' perceptions associated with their satisfactions in the process of using the scholarly resource search functions of the academic version of the NAVER search engine. For this study, the data was collected from a group of undergraduate students, who conducted academic information searches in the field of own major disciplinary areas, using the Web portal. Based on the data, students' satisfactions and dissatisfactions along with the reasons of their perceptions were analyzed. The results presented users' perceptions in various evaluation criteria based on the three major domains: system interfaces, retrieval mechanisms and search results. Based on the results, the study proposed the following suggestions: 1) the enhancements of the system interfaces and HELP guidances based the limited user knowledge on basic system terminologies 2) the improvements of the retrieval mechanisms associated with understanding the contexts of the search terms presented by users 3) the necessity of the user education due to the insufficient user knowledge of the retrieval mechanisms and the search functions.

• Journal of Korean Society of Archives and Records Management
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• v.15 no.4
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• pp.173-194
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• 2015

The study reports a preliminary analysis for the No-Gun Ri massacre documentation strategy based on Hackman and Wornow-Blewett's implementation model, as an appraisal and selection method for No-Gun Ri Digital Archives. It intends to review the theoretical background for this process, inlcuding a history of the No-Gun Ri massacre and the development of documentation strategy. From the theoretical analysis, this study identified the No Gun Ri documentation strategy processes in 5 categories: "cooperative collecting", "collecting in specific areas", "identifing missing areas" and "advisory group". With these 5 categories, this study discusses the application of the Hackman and Wornow-Blewett's implementation model in the No Gun Ri case and reviews the strategy's pros and cons. As a result, firstly, we classfy focusing groups into "victims and bereaved family", "government", "civil society", "the press" and "literature and art". Secondly, we also classify documentation categories into "massacre records", "investigation activity records" and "cherish memory".

• Journal of the Korean Society for Library and Information Science
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• v.43 no.3
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• pp.163-180
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• 2009

In this paper, we describe a developmental system for establishing personal information tendency based on user queries. For each query, the system classified it based on the category information using a kNN classifier. As category information, we used DDC field which is already assigned to each record in the database. The system accumulates category information for all user queries and the user's personalized feature for the target database. We then developed a personalized retrieval system reflecting the personalized feature to produce search result. Our system re-ranks the result documents by adding more weights to the documents for which categories match with the user's personalized feature. By using user's tendency information, the ambiguity problem of the word could be solved. In this paper, we conducted experiments for personalized search and word sense disambiguation (WSD) on a collection of Korean journal articles of science and technology arena. Our experimental result and user's evaluation show that the performance of the personalized search system and WSD is proved to be useful for actual field services.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.5
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• pp.641-656
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• 2019

In this study, a machine learning method was proposed to use in predicting optimal replacement period of shield TBM (Tunnel Boring Machine) disc cutter. To do this, a large dataset of ground condition, disc cutter replacement records and TBM excavation-related data, collected from a shield TBM tunnel site in Korea, was built and they were used to construct a disc cutter replacement period prediction model using a machine learning algorithm, SVM (Support Vector Machine) and to assess the performance of the model. The results showed that the performance of RBF (Radial Basis Function) SVM is the best among a total of three SVM classification functions (80% accuracy and 10% error rate on average). When compared between ground types, the more disc cutter replacement data existed, the better prediction results were obtained. From this results, it is expected that machine learning methods become very popularly used in practice in near future as more data is accumulated and the machine learning models continue to be fine-tuned.

• Journal of The Geomorphological Association of Korea
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• v.19 no.3
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• pp.37-49
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• 2012

The objective of this paper is to propose a methodology for surface sediments classification in tidal flats that can combine ground survey data with high-resolution remote sensing data by multivariate kriging. Unlike conventional methodologies that have classified remote sensing data by using pre-classified sediment components, a new classification methodology presented in this paper first generates sediment component fraction maps and then classifies the sediments on a final stage. For generating sediment component fractions, regression kriging, as one of multivariate kriging algorithms, is applied to integrate ground survey data and remote sensing data. First, trend components of sand, silt, and clay are derived through regression analysis of ground survey data and spectral information from remote sensing data. Then, residuals at sample locations are computed and interpolated to generate residual components in the study area. Finally, the sediment component fractions are computed by adding the residuals to the trend components and are classified on a final stage. A case study at the Baramarae tidal flats with KOMPSAT-2 imagery is carried out to evaluate the classification capability of the proposed classification methodology. Through the case study, the proposed methodology showed the best classification accuracy, compared with the conventional classification methodologies. Especially, much improvement of classification accuracy for fine-grained sediments were also obtained. Therefore, it is expected that the presented classification methodology would be an effective one for surface sediments classification in tidal flats.

• The Journal of the Korea Contents Association
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• v.16 no.5
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• pp.698-709
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• 2016

Free Learning Semester, the new education policy of middle schools in Korea, will be completely implemented in 2016. The purpose of this study was to explore the school experiences of middle-school students in the Free Learning Semester through qualitative approach. In-depth interview was conducted with 8 middle-school students from the purposive sampling. As a result of the analysis, 10 essential themes were identified. Themes were as follows: 'Struggling from the performance evaluation with biting the bullet', 'Great pressure on final examination that is only once a year', 'Inconvenience of career education experience', 'Higher level of friendship', 'Double face of discrimination and respect', 'Chance to adaptation between elementary and middle-school', 'Regret about fleeting time without thought', 'Ambivalence of freedom and suppression', 'Warm place with peer', 'Being pushed rehearsal wearing other's cloth'. In conclusion, the nature of lived experience of middle-school students in the Free Learning Semester is based on ambivalence of various aspects, but is predominant in 'higher level of friendship'. It suggested that the Free Learning Semester can be a positive alternative to existing education system that made students to compete each other. It is expected to be able to discuss the future policy direction using the result of this study which explored the nature of lived experience related to the Free Learning Semester.

• The KIPS Transactions:PartA
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• v.12A no.5 s.95
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• pp.395-404
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• 2005

There have been large concerns about survivability defined as the capability of a system to perform a mission-critical role, in a timely manner, in the presence of attacks, failures. In particular, One of the most important core technologies required for the design of the ITS(Intrusion Tolerance System) that performs continuously minimal essential services even when the computer system is partially compromised because of intrusions is the survivability one of In included the dependability analysis of a reliability and availability etc. quantitative dependability analysis of the In. In this Paper, we applied self-healing mechanism utilizing two factors of self-healing mechanism (fault model and system response), the core technology of autonomic computing to secure the protection power of the ITS and consisted of a state transition diagram of the ITS composed of a primary server and a backup server. We also defined the survivability, availability, and downtime cost of the ITS, and then performed studies on simulation experiments and two cases of vulnerability attack. Simulation results show that intrusion tolerance capability at the initial state is more important than coping capability at the attack state in terms of the dependability enhancement.

• Journal of the Korean Geotechnical Society
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• v.28 no.4
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• pp.101-113
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• 2012

The degradation of a tunnel drainage system leads to increases in pore water pressure around the tunnel and the lining stress, which results in affecting the tunnel stability. In the present study of the Namsan 3th tunnel, more than 30 year old tunnel, the effects of the drainage performance reduction due to drain hole clogging on the tunnel lining stability were investigated by examining pore water pressure distribution around the tunnel and the lining stresses through numerical analysis. Groundwater flow modeling on the Mt. Namsan region was done first and 3D seepage and coupled stress-pore water pressure finite element analysis were performed on the tunnel using the results of the groundwater flow modeling. The pore water pressure distribution and the tunnel lining stresses could be predicted using a drain hole outflow data measured in the tunnel site. This analysis method may be used to evaluate the current stability of old tunnels for which in most cases field investigations and related information are not readily available.

• Journal of Digital Convergence
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• v.17 no.1
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• pp.209-217
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• 2019

In this paper, the purpose of this paper is to lay the foundation for the search system by using and building an online search engine suitable for the search domain and enabling search, conversion, integration and sharing of information. It is to use the ontology to infer hierarchical relationships, deduce objects based on that layer, and extract attributes to search areas that are relevant to the data that the user wants. In order to search for information in this way, the information search system was implemented by entering key words related to 'qualifications'. The implemented system arranged the meaning and relationship of each attribute online so that the general public can search information quickly, easily, and accurately. In addition, the implementation results were compared with two different search engines. Comparable search engines are Naver and Daum, the two major search engines. The search engine of this study, which was built using an ontology suitable for the search domain to perform searches using the semantic web, was evaluated to have excellent results. However, it is thought that a more formalized online location is necessary to increase the accuracy and reliability of search engines and to include more comprehensive categories of search terms.