• Journal of the Korean Society of Safety
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• v.18 no.2
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• pp.98-103
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• 2003

Based on ASME probabilistic risk assessment (PRA) and NEI PRA peer review guidance, we evaluate a human reliability analysis (HRA) in probabilistic safety assessment (PSA) for Korea standard nuclear power plants, Ulchin Unit 3&4, to improve it performed at under design. The HRA for Ulchin Unit 3&4 is assessed as higher than Grade I based on ASME PRA standard and as higher than Grade 2 based on NEI PRA peer review guidance. The major items to be improved identified through the evaluation process are the documentation, the systematic human reliability analysis, the participitation of operators in the works and review of HRA. We suggest the guidance on the identification and qualitative screening analysis for pre-accident human errors and solve some items to be improved using the suggested guidance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.12
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• pp.5826-5841
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• 2019

In our previous research, we proposed a tag emotion-based item recommendation scheme. The ternary associations among users, items, and tags are described as a three-order tensor in order to capture the emotions in tags. The candidates for recommendation are created based on the latent semantics derived by a high-order singular value decomposition technique (HOSVD). However, the tensor is very sparse because the number of tagged items is smaller than the amount of all items. The previous research do not consider the previous behaviors of users and items. To mitigate the problems, in this paper, the item-based collaborative filtering scheme is used to build an extended data. We also apply the probabilistic ranking algorithm considering the user and item profiles to improve the recommendation performance. The proposed method is evaluated based on Movielens dataset, and the results show that our approach improves the performance compared to other methods.

• Journal of KIISE:Software and Applications
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• v.32 no.9
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• pp.901-911
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• 2005

With the development of e-commerce and the proliferation of easily accessible information, information filtering has become a popular technique to prune large information spaces so that users are directed toward those items that best meet their needs and preferences. While many collaborative filtering systems have succeeded in capturing the similarities among users or items based on ratings to provide good recommendations, there are still some challenges for them to be more efficient, especially the user bias problem, non-transitive association problem and cold start problem. Those three problems impede us to capture more accurate similarities among users or items. In this paper, we provide probabilistic model approaches for UCHM and ICHM which are suggested to solve the addressed problems in hopes of achieving better performance. In this probabilistic model, objects (users or items) are classified into groups and predictions are made for users considering the Gaussian distribution of user ratings. Experiments on a real-word data set illustrate that our proposed approach is comparable with others.

• Journal of Korean Institute of Industrial Engineers
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• v.42 no.4
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• pp.249-255
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• 2016

Recently, transaction data is accumulated everywhere very rapidly. Association analysis methods are usually applied to analyze transaction data, but the methods have several problems. For example, these methods can only consider one-way relations among items and cannot reflect domain knowledge into analysis process. In order to overcome defect of association analysis methods, we suggest a transaction data analysis method based on probabilistic graphical model (PGM) in this study. The method we suggest has several advantages as compared with association analysis methods. For example, this method has a high flexibility, and can give a solution to various probability problems regarding the transaction data with relationships among items.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1659-1673
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• 2019

Android platform provides In-app Billing service for purchasing valuable items inside mobile applications. However, it has become a major target for attackers to achieve valuable items without actual payment. Especially, application developers suffer from automated attacks targeting all the applications in the device, not a specific application. In this paper, we propose a novel scheme detecting automated attacks with probabilistic tests. The scheme tests the signature verification method in a non-deterministic way, and if the method was replaced by the automated attack, the scheme detects it with very high probability. Both the analysis and the experiment result show that the developers can prevent their applications from automated attacks securely and efficiently by using of the proposed scheme.

• Journal of Korean Institute of Industrial Engineers
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• v.7 no.2
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• pp.19-26
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• 1981

A special case of the probabilistic multi-location problem is studied in a two-echelon logistic system for deteriorating items. The objective is to determine the location of the minimum number of supply centers among a discrete set of location sites of supply centers, such that the probability each retailer being covered by some supply center is not less than a specified value. A logistic cost is introduced as performance measure of the system, and leads us to analyze the impact of deterioration rate on the location problem. The results obtained from numerical examples are discussed, which provides effective guidelines that can be used for the logistic managerial decisions.

• Nuclear Engineering and Technology
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• v.52 no.1
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• pp.69-77
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• 2020

After the Fukushima Daiichi accidents, public concerns on nuclear safety and the corresponding burden of nuclear power plant licensees are increasing. In order to secure public trust and enhance the rationality of current safety regulation, we develop a risk-informed decision making (RIDM) framework for the Korean regulatory body. By analyzing all the regulatory activities for nuclear power plants in Korea, eight action items are selected for RIDM implementation, with appropriate procedures developed for each. For two items in particular - the accident sequence precursor analysis (ASPA) and the significance determination process (SDP) - two customized risk evaluation software has been developed for field inspectors and probabilistic safety assessment experts, respectively. The effectiveness of the proposed RIDM framework is demonstrated by applying the ASPA procedure to 35 unplanned scrams and the SDP to 24 findings from periodic inspections.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.521-524
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• 2020

국내 모바일 MMORPG 시장에서 구글플레이 스토어, 앱 스토어의 매출 순위를 보면 순위 안에 있는 게임 중에 가챠 시스템이 없는 게임을 찾기가 힘들 정도로 모바일게임에서 가챠 시스템은 게임의 전체 매출에서 많은 비중을 차지한다. 과거 가챠 시스템으로 인하여 사행성과 과금 유도가 너무 심해져 2015년 확률형 아이템 규제 법안이 발의되어 현재까지 게임회사들은 확률을 공개해왔다. 하지만 공개된 확률에는 유저들이 모르는 큰 오류가 존재한다. 본 논문에서 그 오류를 알아보고 모바일 게임 가챠 시스템의 건전성을 확보하기 위한 방안을 제시하고자 한다.

• Smart Media Journal
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• v.2 no.2
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• pp.20-27
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• 2013

The concept of social media is top of the agenda for many business executives and decision makers, as well as consultants try to identify ways where companies can make profitable use of applications such as Netflix, Flixster. The social media is playing an increasingly important role as the information sources for customers making product choices etc. With the flourish of Web 2.0 technology, customer reviews are becoming more and more useful and important information resources for people to save their time and energy on purchasing products that they want. This paper proposes the Bayesian Probabilistic Classification algorithm to mine the social media review, and evaluates it by different splits and cross validation mechanism from the real data set. The explored study experimental results show the robustness and effectiveness of proposed approach for mining the social media review.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.226-232
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• 2000

Seismic probabilistic risk assessment(RA) rather than deterministic assessment provides more valuable information and insight for resolving seismic safety issues in nuclear power plant design. In the course of seismic PRA seismic fragility analysis is the most significant and essential phase especially for structural or mechanical engineers. Lately the seismic fragility analysis is taken as a useful tool in general structural engineering as well. A systemized and synthesized procedure or technology related to seismic fragility analysis of critical industrial facilities reflecting the unique experiences and database in Korea is urgently required. This paper gives a state-of-the-art reviews of PRA and briefly summarizes the technologies related to PRA and seismic fragility analysis before developing an unique technology considering characteristics of Korean database. Some key items to be resolved theoretically or technically are extracted and presented for the future research.