• Composites Research
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• 제28권4호
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• pp.162-167
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• 2015

Composite sandwich structures are widely employed in various applications, due to their high specific stiffness and specific bending strength compared to solid panels. Lately, for that reason, the advanced composite sandwich structures are employed in satellite structures: materials should be as light as possible with the highest attainable performance. This study is majorly focused on inserts employed to the composite sandwich satellite structures. A new hybrid insert design was developed in precedent study to reduce the mass of the sandwich structure since the mass of the satellite structure is related to high launching cost [1]. In this study, the thermal characteristics and behavior of the precedently developed hybrid insert with carbon composite reinforcing web and the conventional partial insert were numerically investigated.

• Journal of Fisheries and Marine Sciences Education
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• 제28권2호
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• pp.376-383
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• 2016

In this paper, the blue-green algae monitoring program of applying IoT(Internet of things) technologies is designed and implemented that can check out the status of the river's water quality in real time. The proposed system is to extract the image data from the camera of raspberry pi by an wireless network, and it is analyzed through the HSV color model. We measure the temperature using a DS18B20 1-wire temperature sensor. The extracted information of image data and temperature is then analyzed in C and Python programs for use with Raspberry Pi. The XML data in PHP program is made from the analyzed information and provides Web services. It also allows to refer the XML data using mobile devices.

• Journal of the Korea Institute of Information Security & Cryptology
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• 제6권4호
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• pp.53-66
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• 1996

World Wide Web is a total solution for multi-media data transmission on Internet. Because of its characteristics like ease of use, support for multi-media data and smart graphic user interface, WWW has extended to cover all kinds of applications. The Secure Information Center(SIC) is a data transmission system using conventional cryptography between client and server on WWW. It's main function is to support the encryption of sending data. For encryption of data IDEA(International Data Encryption Algorithm) is used and for authentication mechanism MD5 hash function is used. Since Secure Information Center is used by many users, conventional cryptosystem is efficient in managing their secure interactions. However, there are some restrictions on sharing of same key and data transmission between client and server, for example the risk of key exposure and the difficulty of key sharing mechanisms. To solve these problems, the Secure Information Center provides encryption mechanisms and key management policies.

• Annual Conference of KIPS
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• 한국정보처리학회 2023년도 추계학술발표대회
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• pp.75-76
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• 2023

쿠버네티스는 컨테이너 오케스트레이션 플랫폼으로, 마이크로서비스 운영에 널리 사용된다. 이는 쿠버네티스가 오토스케일링을 지원하여 서비스 제공자가 부하의 변동에 효과적으로 대응할 수 있도록 지원하기 때문이다. 본 논문은 쿠버네티스 환경에서 runc 와 runsc 두 런타임을 대상으로 CPU 및 I/O 집약적 부하를 주는 웹 애플리케이션을 실행하여 처리 성능을 분석했다. 분석 결과 초당 요청 수가 일정 수준을 넘자 성능이 급락하였으며, 이를 바탕으로 워크로드를 고려한 오토스케일링의 필요성을 제고한다.

• The Journal of the Korea institute of electronic communication sciences
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• 제8권3호
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• pp.487-498
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• 2013

A variety of location-based services applications, such as missing children search, emergency rescue requests and so on that requiring high-precision location information are increasing. Precision of GPS that can be used in most systems, however, is still low. In this paper, we design and propose a low cost differential global positioning system(DGPS) based on Web services using object-oriented modeling technique which can offer useable location service, variety device and safe service in wireless environment. The proposed system is designed with UML based on object-oriented modeling to maximize system recyclability and system scalability. In addition, we would like to improve the precision of the GPS in accordance with mobile station location when build low cost mobile station, location differential framework and server. We implement a communication interface based on web-service which is available in the form of a variety of services and can offer stable according to mobile environments. Finally, as performance evaluation results, we can obtain precision location within 1 ~ 2m through proposed system and 88.5% probability of less than 2m.

• Journal of rehabilitation welfare engineering & assistive technology
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• 제9권3호
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• pp.195-201
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• 2015

In this study, IT education contents have been developed based on the u-Learning approach for people with hearing impairment, focusing on allowing the user to learn from anywhere and anytime. Specifically, this study applies HTML5 to implementing IT education contents(JSP, Oracle) for the deaf because HTML5 enables the learner to access the contents through both web and mobile device on various platforms including android, Mac OS, and PC etc. The results of this study are as follows: First, the online computer courses are mostly supposed to be compatible with diverse types of mobile devices. However, some of the contents could not be run on applications residing in web and mobile devices because the contents tend to be developed using FLASH. HTML5 is the effective way to overcome the compatibility problem. Second, FLASH and HTML5 contents authoring tools have been compared in terms of their strong and weak points by applying the developed contents to those tools. The study also suggests that the future work would be needed in order to implement wide variety of event functions with HTML5. Lastly, design strategies enabling access through web and mobile devices have been analyzed in accordance with u-Learning design guidelines for the deaf and mobile application accessibility guidelines. However, in the latter case, the future work regarding design guidelines needs to be conducted to improve the educational accessibility depending on the level of impairment.

• Journal of the Korea Society of Computer and Information
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• 제17권12호
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• pp.169-177
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• 2012

In the development process of application systems, the most important works are analysis and design. Most of the application systems are implemented on database system. So, database design is important. Also, IT System are confronted with more and more attacks by an increase interconnections between IT systems. Therefore security-related processes belong to a very important process. Security is a complex non-functional requirement that can interaction of many parts in the system. But Security is considered in the final stages of development. Therefore, Their increases the potential for the final product to contain vulnerabilities. Accordingly, Early in development related to security analysis and design process is very important. J2EE gives a solution based on RBAC((Role Based Access Control) for security and object-relational database also has RBAC for security. But there is not a object-oriented analysis and design methodology using RBAC of J2EE and object-relational database for security. In this paper, the unified object-oriented analysis and design methodology is developed for security-critical web application systems based on J2EE and object-relational database. We used UMLsec and RBAC of object-relational database and J2EE for this methodology.

• Journal of the Institute of Electronics Engineers of Korea TC
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• 제41권5호
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• pp.37-45
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• 2004

As Internet technologies are mature, many new applications that are different characteristics are emerging. Recently we see wide use of P2P(Peer to Peer) applications of which traffic shows different statistical characteristics compared with traditional application such as web(HTTP) and FTP(File Transfer Protocol). In this paper, we measured subscriber network of KT(Korea Telecom) to analyze P2P traffic characteristics. We show flow characteristics of measured traffic. We also estimate Hurst parameter of P2P traffic and compare self-similarity with web traffic. Analysis results indicate that P2P traffic is much bustier than web traffic and makes both upstream traffic and downstream traffic be symmetric. To predict parameters related QoS such as packet loss and delays we model P2P traffic using two self-similar traffic models and predict both loss probability and mm delay then compare their accuracies. With simulation we show that the self-similar traffic models we derive predict the performance of P2P traffic accurately and thus when we design a network or evaluate its performance, we can use the P2P traffic model as reference input traffic.

• KIISE Transactions on Computing Practices
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• 제21권4호
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• pp.320-326
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• 2015

With the growing concern over frequent occurrences of criminal events, help-requesting mobile applications have drawn attention. However, existing applications solely focus on providing help-requesting services. Therefore, in this paper, we design and implement a help request and response process which allows users to request help by sending messages and locating their friends, acquaintances and even near-by application users, and to allow help be reached by forwarding messages. This application is composed of three parts: help-requesting, help-responding, and checking-status. This application is developed on the Android platform where we exchange users' longitude and latitude through web server communication. We conducted test to verify the effectiveness of the forwarding function, and it has been confirmed that 93.33% of subjects used the forwarding function to help users at risk.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• 제12권2호
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• pp.111-117
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• 2012

With the rapid growth of smart phone technologies, mobile user's demands for using services provided by existing web or portal cites are highly increased. These services, however, are designed for the environment of desktop PCs or laptops in general, so it requires lots of costs for corrections and has difficulties for system protection to use in current mobile devices. In this paper, we design and implement a middleware for android-based smart phone apps to cooperate with a portal system with minimum corrections and function configuration. Our middleware system is working as an interface between an existing portal system and mobile devices to provide harmonious usage and safe system protection.