• Journal of Power Electronics
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• 제14권3호
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• pp.421-431
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• 2014

A DSP-based self-adaptive proportional-integral (PI) controller to control a DC-DC converter is proposed in this paper. The full-bridge topology is adopted here to obtain higher power output capability and higher conversion efficiency. The converter adopts the zero-voltage-switching (ZVS) technique to reduce the conduction losses. A parallel secondary active clamp circuit is added to deal with the voltage overshoot and ringing effect on the transformer's secondary side. A self-adaptive PI controller is proposed to replace the traditional PI controller. Moreover, the designed converter adopts the constant-current and constant-voltage (CC-CV) output control strategy. The secondary active clamp mechanism is discussed in detail. The effectiveness of the proposed converter was experimentally verified by an IGBT-based 10kW prototype.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.827-828
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• 2011

• 한국산학기술학회논문지
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• 제11권12호
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• pp.4962-4967
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• 2010

스마트 카드는 암호알고리즘의 개발과 더불어 전자상거래 환경이 구축되면서 가치이전의 수단 및 활용분야가 다양하기 때문에 정보 통신망 환경에서 중요한 보안 장치로 수요나 활용면에서 급격한 증가율을 보이고 있다. 따라서 본 논문에서 제안한 스마트 카드용 키 스케쥴러 블록은 다양한 멀티미디어 및 실시간 통신의 암호시스템에 적용할 경우 기존시스템과 호환성이 용이하여 하드웨어 설계와 비도 및 처리속도를 향상시킬 수 있다고 사료된다.

• 전기학회논문지
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• 제60권2호
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• pp.416-422
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• 2011

Smart grid is the next generation intelligent power grid that combines the existing electric power infrastructure and information infrastructure. It can optimize the energy efficiency in both directions, suppliers and power consumers to exchange information in real time. In smart grid environments, with existing network security threats due to the smart grid characteristics, there are additional security threats. In this paper, we propose a security mechanism that provides mutual authentication and key agreement between a remote user and the device. The proposed mechanism has some advantages that provides secure mutual authentication and key agreement and secure against a replay attack and impersonation attacks.

• Journal of Information Technology Applications and Management
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• 제30권6호
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• pp.1-15
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• 2023

With the advent of the Fourth Industrial Revolution, propelled by digital technology, we are transitioning into an era of hyperconnectivity, where everything and objects are becoming interconnected. A smart supply chain refers to a supply chain system where various sensors and RFID tags are attached to objects such as machinery and products used in the manufacturing and transportation of goods. These sensors and tags collect and analyze process data related to the products, providing meaningful information for operational use and decision-making in the supply chain. Before the spread of COVID-19, the fundamental principles of supply chain management were centered around 'cost minimization' and 'high efficiency.' A smart supply chain overcomes the linear delayed action-reaction processes of traditional supply chains by adopting real-time data for better decision-making based on information, providing greater transparency, and enabling enhanced collaboration across the entire supply chain. Therefore, in this study, a hierarchical model for building a smart supply chain was constructed to systematically derive the importance of key factors that should be strategically considered in the construction of a smart supply chain, based on the major factors identified in previous research. We applied AHP (Analytical Hierarchy Process) techniques to identify urgent improvement areas in smart SCM initiatives. The analysis results showed that the external supply chain integration is the most urgent area to be improved in smart SCM initiatives.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권5호
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• pp.1313-1327
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• 2013

How to make people keep both the confidentiality of the sensitive data and the privacy of their real identity in communication networks has been a hot topic in recent years. Researchers proposed privacy-preserving authenticated key exchange protocols (PPAKE) to answer this question. However, lots of PPAKE protocols need users to remember long secrets which are inconvenient for them. In this paper we propose a lightweight three-party privacy-preserving authentication key exchange (3PPAKE) protocol using smart card to address the problem. The advantages of the new 3PPAKE protocol are: 1. The only secrets that the users need to remember in the authentication are their short passwords; 2. Both of the users can negotiate a common key and keep their identity privacy, i.e., providing anonymity for both users in the communication; 3. It enjoys better performance in terms of computation cost and security. The security of the scheme is given in the random oracle model. To the best of our knowledge, the new protocol is the first provably secure authentication protocol which provides anonymity for both users in the three-party setting.

• 한국멀티미디어학회논문지
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• 제16권2호
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• pp.180-189
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• 2013

SMART Highway 사업은 첨단 IT통신과 자동차 및 도로 기술이 접목된 세계 최고수준의 빠르고 편안한 지능형 녹색도로 실현을 목표로 하고 있다. SMART Highway의 도로-자동차 기반 교통운영의 핵심기술인 VANET(Vehicular Ad-hoc Network)은 다수의 차량들이 무선통신을 이용하여 차량 간 통신 또는 차량과 RSU(Road Side Unit)사이의 통신을 제공하는 차세대 네트워킹 기술이다. 특히, 운전자의 안전에 직접적인 영향을 끼칠 수 있는 V2V 통신의 경우 차량 간의 안전한 통신을 위해 안전한 키 교환이 반드시 고려되어야 한다. 이처럼 빠른 속도로 이동하는 차량 간 안전한 키 교환이 원활이 이루어지기 위해서는 기존의 네트워크에서 사용된 방식은 그대로 적용시키기 어렵다. 따라서 본 논문에서는 다수의 차량 간 통신 시에 보다 효율적이고 안전한 키 교환을 위해 사인크립션을 이용한 차량 간 그룹키 교환기법을 제안한다.

• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.1921-1929
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• 2015

The smart substation is the heart of a transmission system, which is particularly emphasized as the most significant composition of smart grids in China. In order to assess the functionality performance of substation technologies, this paper presents methods used to identify the most promising solutions for smart substation design and to evaluate the technical levels of available technologies. The multi-index optimization model is presented to address the issue of smart substation planning. A mathematical model of the planning decision problem is established with multiple objectives consisting of economic, reliability, and green key indices, and many kinds of concerns including physical and environmentally friendly operations are formulated as a set of constraints. With respect to the assessment of the technical level regarding integration of advanced technologies into a substation, a modified grey whitenization weight function is adopted to structure a novel grey clustering method. The proposed grey clustering approach is used to overcome the difficulty of insufficient quantitative assessment capacity for traditional methods. The evaluation of technical effects provides the classification definition for the development phase and the maturity level of the smart substation. The effectiveness of the proposed approaches in planning decision-making and evaluation of construction efforts is demonstrated with case studies involving the actual smart substation projects of Wenchongkou substation in China Southern Power Grid (CSG) and Mengzi substation in State Grid Corporation of China (SGCC).

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권3호
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• pp.1510-1532
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• 2017

In smart grid, privacy implications to individuals and their families are an important issue because of the fine-grained usage data collection. Wireless communications are utilized by many utility companies to obtain information. Network coding is exploited in smart grids, to enhance network performance in terms of throughput, delay, robustness, and energy consumption. However, random linear network coding introduces a new challenge for privacy preserving due to the encoding of data and updating of coefficients in forwarder nodes. We propose a distributed privacy preserving scheme for random linear network coding in smart grid that considers the converged flows character of the smart grid and exploits a homomorphic encryption function to decrease the complexities in the forwarder node. It offers a data confidentiality privacy preserving feature, which can efficiently thwart traffic analysis. The data of the packet is encrypted and the tag of the packet is encrypted by a homomorphic encryption function. The forwarder node random linearly codes the encrypted data and directly processes the cryptotext tags based on the homomorphism feature. Extensive security analysis and performance evaluations demonstrate the validity and efficiency of the proposed scheme.

• International Journal of Internet, Broadcasting and Communication
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• 제14권3호
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• pp.91-100
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• 2022

Major developed countries are seriously considering smart factories to increase their manufacturing competitiveness. Smart factory is a customized factory that incorporates ICT in the entire process from product planning to design, distribution and sales. This can reduce production costs and respond flexibly to the consumer market. The smart factory converts physical signals into digital signals, connects machines, parts, factories, manufacturing processes, people, and supply chain partners in the factory to each other, and uses the collected data to enable the smart factory platform to operate intelligently. Enhancing personalized value is the key. Therefore, it can be said that the success or failure of a smart factory depends on whether big data is secured and utilized. Standardized communication and collaboration are required to smoothly acquire big data inside and outside the factory in the smart factory, and the use of big data can be maximized through big data analysis. This study examines big data analysis and standardization in smart factory. Manufacturing innovation by country, smart factory construction framework, smart factory implementation key elements, big data analysis and visualization, etc. will be reviewed first. Through this, we propose services such as big data infrastructure construction process, big data platform components, big data modeling, big data quality management components, big data standardization, and big data implementation consulting that can be suggested when building big data infrastructure in smart factories. It is expected that this proposal can be a guide for building big data infrastructure for companies that want to introduce a smart factory.