• Journal of Korean Society of Transportation
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• v.22 no.3 s.74
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• pp.167-177
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• 2004

The Hub-and-spoke strategy is widely used in the field of transportation. According to containerization and the development of transshipment technology, it is also introduced into European rail freight transportation. The objective of this article is to develop a service network design model for rail freight transportation based on the Hub-and-spoke strategy and efficient algorithms that can be applied to large-scale network. Although this model is for strategic decision, it includes not only general operational cost but also time-delay cost. The non-linearity of objective function due to time-delay factor is transformed into linearity by establishing train service variables by frequency. To solve large scale problem, this model used a heuristic method based on decomposition and three newly-developed algorithms. The new algorithms were examined with respect to four test problems base on the actual network of European rail freight and discussed the accuracy of solutions and the efficiency of proposed algorithms.

• Journal of Digital Convergence
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• v.19 no.11
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• pp.463-470
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• 2021

Due to natural and human factors, dunhuang frescoes in China have gradually degenerated. China has conducted digital transformation of frescoes since 1990. However, it requires expensive research costs. Most of the visitors passively accept transformation contents and lack subjective participation. The paper focuses on produces a prototype of Dunhuang frescoes on the CoSpaces EDU. It was implemented as a metaverse through procedures such as transforming the cave into 3D, mapping images to the cave model and developing CoBlocks. The research puts forward a more specific methodology without expensive costs of development. The paper makes it easier to realize the immersive and interactive virtual Dunhuang frescoes world, to improve the tourism contents and educational effect. This research carries on the statistics to the product result which develops according to the user experience of 100 different ages, has obtained the good feedback. The research results need to be improved is to strengthen the processing of graphic details. Therefore, Optimization and improvement of the result will be carried out in the future research.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.3
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• pp.167-175
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• 2018

Despite the rapid development of IT technology, people with visual impairments still use simple forms of walking sticks and need more advanced walking aids. Smart Cane, which is developed based on Internet service and sensor, can provide high safety and convenience compared to existing sticks for visually impaired people by conveying peripheral information and walking situation to these visually impaired people through voice and vibration. In this paper, we propose and implement SmartKane to overcome lack of miniaturization, user friendly form, and sensing sensitivity, which have been pointed out as a problem of existing SmartKane.

• The Journal of Bigdata
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• v.2 no.2
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• pp.9-16
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• 2017

Global Platform Solution Company (aka Amazon, Google, MS, IBM) who has cloud platform, are driving AI and Big Data service on their cloud platform. It will dramatically change Enterprise business value chain and infrastructures in Supply Chain Management, Enterprise Resource Planning in Customer relationship Management. Enterprise are focusing the channel with customers and Business Partners and also changing their infrastructures to platform by integrating data. It will be Digital Transformation for decision support. AI and Deep learning technology are rapidly combined to their data driven platform, which supports mobile, social and big data. The collaboration of platform service with business partner and the customer will generate new ecosystem market and it will be the new way of enterprise revolution as a part of the 4th industrial revolution.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.290-290
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• 2010

현재 세계적으로 화석연료의 고갈로 인해 신재생에너지에 대한 관심이 모아지고 있다. 그중에서 태양전지가 가장 주목을 받고 있으며 태양전지는 크게 무기와 유기 태양전지로 구분된다. 실리콘 및 화합물 반도체를 이용한 무기 태양전지는 높은 에너지 변환 효율을 보이고 있으나 생산단가가 높아 화석연료로부터 얻는 에너지에 비해 경제성이 떨어진다. 그중에서 유기 태양전지는 무기 태양전지의 효율에는 미치지 못하지만 제작공정의 비용이 낮고, 투명하고 다양한 색을 나타낼 수 있으며, 특히 유연성을 바탕으로 원하는 제품의 디자인을 구현 할 수 있는 장점을 가진다. Inverted 구조는 conventional 구조에 비해 Al과 같은 air-sensitive한 전극을 대체 할 수 있다는 장점을 가진다. 본 연구에서는 sol-gel상의 ZnO를 스핀코팅 방법으로 박막을 형성하여 inverted 구조 형태의 유무기 하이브리드 태양전지를 제작하였으며, ZnO 코팅 공정 조건 (두께, 열처리 온도)에 따른 태양전지의 특성변화(광 변환효율 및 수명 등)를 관측하였다. 최적화된 ZnO의 공정조건에서 제작된 하이브리드 태양전지는 3% 이상의 광 변환효율과 1000시간 이상의 반감 수명을 가지는 우수한 특성을 보였다.

• Journal of Digital Contents Society
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• v.9 no.1
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• pp.7-15
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• 2008

The paper proposes information system for providing proper well known delicious restaurants as interactions with users. The system calls 'Moloke', which is an agent for recommending sensitive information on mobile environment The proposing agent differs from existing ones that guide the telephone number and the name of the restaurant. The differences are as following goals. First, the agent gets existing from users as interactive communications on mobile devices through the proper requests on each time zone such as morning, afternoon, and evening. Second, the agent also can recommend a specific restaurant for current personal states such as parties, special community meetings, bio-rhythms and so on. Among them, specially the bio-rhythm is used for recommending proper restaurants to each user. In addition to through proposal suitable design for the mobile agent design more effectively. The research used mobile environment for recommendation service and web environment for data management. Server environment for service used Apache, PHP4, Mysql and mobile page was implemented m-html for approach. Mobile Service was optimized Mozilla-1.22, KUN-1.2.3 Browser

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.1
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• pp.205-214
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• 2019

Android uses app cache files to improve app execution performance. However, this optimization technique may raise security issues that need to be examined. In this paper, we present a practical design of "Android app cache manipulation attack" to intentionally modify the cache files of a target app, which can be misused for stealing personal information and performing malicious activities on target apps. Even though the Android framework uses a checksum-based integrity check to protect app cache files, we found that attackers can effectively bypass such checks via the modification of checksum of the target cache files. To demonstrate the feasibility of our attack design, we implemented an attack tool, and performed experiments with real-world Android apps. The experiment results show that 25 apps (86.2%) out of 29 are vulnerable to our attacks. To mitigate app cache manipulation attacks, we suggest two possible defense mechanisms: (1) checking the integrity of app cache files; and (2) applying anti-decompilation techniques.

• Journal of the Korea Society of Computer and Information
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• v.14 no.7
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• pp.123-132
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• 2009

The perforrnance and portability of mobile applications can be greatly increased by adopting proxy modiles which exists between the conventional system and the device. When mobile devices collaborate with the conventional computers, there are problems to address: a battery life problem, limited input and output methods, and intermittent wireless connection. Those issues are magnified in the multimedia collaboration environment since it works in a real-time condition and the size of the message in the system is big in many cases. Additionally, because multimedia collaboration system softwares are too heavy and complex for mobile devices, it is veη hard to integrate them with conventional systems. In this paper, we describe our design and its implementation of a novel approach to map events (i.e. messages) using a proxy for mobile applications. We adopt a proxy to provide a content adaptation (i.e. transcoding) where the message contents are customized. Also, we design a mobile version publish/subscribe system to provide communication service for mobile device in loosely coupled and flexible manner. We present our empirical results which show that our design can be efficiently implemented and integrated with a conventional multimedia collaboration system.

• Korean Journal of Cognitive Science
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• v.19 no.4
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• pp.331-367
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• 2008

This study aims to validate a web-based neuropsychological testing tool developed by Kwak(2007) and to suggest solutions to potential problems that can deteriorate its validity. When it targets a wider range of subjects, a web-based neuropsychological testing tool is challenged by high drop-out rates, lack of motivation, lack of interactivity with the experimenter, fear of computer, etc. As a possible solution to these threats, this study aims to redesign the user interface of a web-based attention testing tool through three phases of study. In Study 1, an extensive analysis of Kwak's(2007) attention testing tool was conducted to identify potential usability problems. The Heuristic Walkthrough(HW) method was used by three usability experts to review various design features. As a result, many problems were found throughout the tool. The findings concluded that the design of instructions, user information survey forms, task screen, results screen, etc. did not conform to the needs of users and their tasks. In Study 2, 11 guidelines for the design of web-based attention testing tools were established based on the findings from Study 1. The guidelines were used to optimize the design and organization of the tool so that it fits to the user and task needs. The resulting new design alternative was then implemented as a working prototype using the JAVA programming language. In Study 3, a comparative study was conducted to demonstrate the excellence of the new design of attention testing tool(named graphic style tool) over the existing design(named text style tool). A total of 60 subjects participated in user testing sessions where their error frequency, error patterns, and subjective satisfaction were measured through performance observation and questionnaires. Through the task performance measurement, a number of user errors in various types were observed in the existing text style tool. The questionnaire results were also in support of the new graphic style tool, users rated the new graphic style tool higher than the existing text style tool in terms of overall satisfaction, screen design, terms and system information, ease of learning, and system performance.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.4
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• pp.9-15
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• 2012

With the rise of internet and e-commerce, this is more applicable now than ever. People rely on computer networks to provide them with news, stock prices, e-mail and online shopping. People's credit card details, medical records and other personal information are stored on computer systems. Many companies have a web presence as an essential part of their business. The research community uses computer systems to undertake research and to disseminate findings. The integrity and availability of all these systems have to be protected against a number of threats. Amateur hackers, rival corporations, terrorists and even foreign governments have the motive and capability to carry out sophisticated attacks against computer systems. Therefore, the field of information and communication security has become vitally important to the safety and economic well being of society as a whole. This paper provides an overview of IDS and IPS, their functions, detection and analysis techniques. It also presents comparison of security capability and characteristics of IDPS techniques. This will make basis of IDPS(Intrusion Detection and Protection System) technology integration for a broad-based IDPS solutions