• 한국정보통신학회논문지
• /
• 제17권6호
• /
• pp.1462-1470
• /
• 2013

본 논문에서는 클러스터 단위로 센서 노드의 키와 그룹키를 생성한 후 분배하는 KGDC(Key Generation and Distribution based on Cluster) 모듈과 이 키를 이용하여 시빌 공격과 웜홀 공격을 탐지할 수 있는 SWAD(Sybil & Wormhole Attack Detection) 모듈로 구성되는 SWAD-KNH(Sybil & Wormhole Attack Detection using Key, Neighbor list and Hop count) 기법을 제안한다. KGDC 모듈은 ECDH 알고리즘, 해시함수, 키 체인 기법을 이용하여 그룹키와 센서 노드의 키들을 생성하고 안전하게 배포한다. SWAD 모듈은 2단계 키 확인절차를 수행함으로써 시빌 공격 탐지를 강화시키고, 근원지와 목적지 노드의 공동이웃노드들의 수와 홉 카운트를 이용하여 웜홀 공격을 탐지한다. 그 결과 SWAD-KNH 기법은 시빌 공격 탐지율은 91.2%, 평균 FPR(False Positive Rate)은 3.82%이고, 그리고 웜홀 공격 탐지율은 90%, 평균 FPR(False Positive Rate)은 4.64%으로 평가되므로 시빌과 웜홀 공격 탐지율 및 시빌과 웜홀 공격 탐지의 신뢰성을 향상시켰다.

• Journal of Power Electronics
• /
• 제17권4호
• /
• pp.849-859
• /
• 2017

This paper illustrates the analysis and design of a multi-resonant converter applied to an electric vehicle (EV) charger. Thanks to the notch resonant characteristic, the multi-resonant converter achieve soft switching and operate with a narrowed switching frequency range even with a wide output voltage range. These advantages make it suitable for battery charging applications. With two more resonant elements, the design of the chosen converter is more complex than the conventional LLC resonant converter. However, there is not a distinct design outline for the multi-resonant converters in existing articles. According to the analysis in this paper, the normalized notch frequency $f_{r2n}$ and the second series resonant frequency $f_{r3n}$ are more sensitive to the notch capacitor ratio q than the notch inductor ratio k. Then resonant capacitors should be well-designed before the other resonant elements. The peak gain of the converter depends mainly on the magnetizing inductor ratio $L_n$ and the normalized load Q. And it requires a smaller $L_n$ and Q to provide a sufficient voltage gain $M_{max}$ at ($V_{o\_max}$, $P_{o\_max}$). However, the primary current increases with $(L_nQ)^{-1}$, and results in a low efficiency. Then a detailed design procedure for the multi-resonant converter has been provided. A 3.3kW prototype with an output voltage range of 50V to 500V dc and a peak efficiency of 97.3 % is built to verify the design and effectiveness of the converter.

• 한국정보통신학회논문지
• /
• 제20권12호
• /
• pp.2282-2288
• /
• 2016

보안키 생성기법으로 하드웨어 또는 소프트웨어 관련 생성기법들이 다양하게 제안되고 있다. 본 연구는 기존의 보안키 생성기법들을 분석하여, NAND 플래시 메모리의 Bad Block 정보를 이용하는 새로운 보안키인 NBSK(NAND Bad block based Secure Key)을 설계하고 이를 이용한 암호화기법을 제안한다. NAND 플래시 메모리에 존재하는 Bad Block은 생산중에 발생하기도 하고 사용 도중에 발생하기도 한다. 생산중 발생하는 초기 Bad Block 정보는 변하지 않으며, 사용도중 발생하는 Bad Block 정보는 주기적으로 변할 수 있다는 특성을 가지고 있다. 따라서 본 연구는 NAND 플래시 메모리 생산중에 발생하는 초기의 Bad Block 정보의 물리주소를 이용하여 보안키로 활용할 수 있도록 암호화키를 설계하고 이를 이용한 암호화 기법을 제안한다. 제안 기법을 이용하면 보안키의 생성과 분배의 단순성과 보안키의 인증성과 기밀성 등의 일반적인 보안 특성을 만족할 수 있다.

• 디지털산업정보학회논문지
• /
• 제13권1호
• /
• pp.87-101
• /
• 2017

As people increasingly rely on mobile networks in modern society, mobile communication security is becoming more and more important. In the Long Term Evolution/System Architecture Evolution (LTE/SAE) architecture, the 3rd Generation Partnership (3GPP) team has also developed the improved Evolved Packet System Authentication and Key Agreement (EPS AKA) protocol based on the 3rd Generation Authentication and Key Agreement (3G AKA) protocol in order to provide mutual authentication and secure communication between the user and the network. Unfortunately, the EPS AKA also has several vulnerabilities such as sending the International Mobile Subscriber Identity (IMSI) in plain text (which leads to disclosure of user identity and further causes location and tracing of the user, Mobility Management Entity (MME) attack), man-in-middle attack, etc. Hence, in this paper, we analyze the EPS AKA protocol and point out its deficiencies and then propose an Efficient and Security Enhanced Authentication and Key agreement (ESE-EPS AKA) protocol based on hybrid of Dynamic Pseudonym Mechanism (DPM) and Public Key Infrastructure (PKI) retaining the original framework and the infrastructure of the LTE network. Then, our evaluation proves that the proposed new ESE-EPS AKA protocol is relatively more efficient, secure and satisfies some of the security requirements such as confidentiality, integrity and authentication.

• 정보처리학회논문지C
• /
• 제12C권7호
• /
• pp.973-980
• /
• 2005

본 논문에서는 기존의 암호화 방법보다 다양한 키를 생성하는 알고리즘을 제안하고, 키 생성 알고리즘을 통해 각각 생성된 대칭키를 서버에 저장하지 않는 기존의 시스템보다 보안성이 높은 DRM 암호화 시스템을 제안한다. 또한 클라이언트에서 복호화 할 때 각각의 키를 유추하여 복호화 하는 클라이언트 시큐리티 에이전트 시스템을 제안한다. 제안한 시스템을 설계하고 구현한 후 성능 평가를 위해 다양한 크기의 비디오 데이터 파일을 이용하여 실험을 수행하여 제안한 시스템이 기존 시스템에 비해 비디오 데이터 파일 재생 시 암호화 복호화 시간을 포함한 지연시간을 줄어 든 것을 검증하였다.

• Journal of Power Electronics
• /
• 제17권5호
• /
• pp.1308-1316
• /
• 2017

The distributed maximum power point tracking (DMPPT) concept is widely adopted in photovoltaic systems to avoid mismatch loss. However, the high cost and complexity of DMPPT hinder its further promotion in practice. Based on the concept of DMPPT, this paper presents an integrated submodule level half-bridge stack structure along with an optimal current point tracking (OCPT) control algorithm. In this full power processing integrated solution, the number of power switches and passive components is greatly reduced. On the other hand, only one current sensor and its related AD unit are needed to perform the ideal maximum power generation for all of the PV submodules in any irradiance case. The proposal can totally eliminate different small-scaled mismatch effects in real-word condition and the true maximum power point of each PV submodule can be achieved. As a result, the ideal maximum power output of the whole PV system can be achieved. Compared with current solutions, the proposal further develops the integration level of submodule DMPPT solutions with a lower cost and a smaller size. Moreover, the individual MPPT tracking for all of the submodules are guaranteed.

• 정보보호학회논문지
• /
• 제14권3호
• /
• pp.137-144
• /
• 2004

3GPP-WLAN(3rd Generation Partnership Project-Wireless Local Area Network) interworking은 WLAN UE(user equipment)에 의한 3GPP 시스템내에서 자원 이용과 서비스 접근을 의미하며, 3GPP 서비스와 기능을 WALN 액세스 환경으로 확장함으로써, 3GPP 시스템에 무선 액세스 기술로 WLAN을 보완적으로 이용하는 것을 목적으로 한다. 본 논문에서는 3GPP-WLAN interworking에서 UE 개시 터널 설정을 위한 효율적인 메커니즘을 제안한다. 제안된 메커니즘은 UE와 3GPP AAA(Authentication, Authorization Accounting) 서버 사이의 인증과 키 일치 과정에서 미리 분배된 비밀키에 기반 한다. 따라서 UE에서 많은 계산을 필요로 하는 모듈러 지수승 연산과 공개키 서명 연산을 피할 수 있다. 또한 제안된 기법은 UE와 PDGW(Packet Data Gateway) 사이에 상호 인증과 세션 키 설정을 제공한다.

• Journal of Electrical Engineering and Technology
• /
• 제11권2호
• /
• pp.300-308
• /
• 2016

Application of demand-side resources to automatic generation control (AGC) has a great significance for improving the dynamic control performance of power system frequency regulation. This paper investigates the possibility of providing regulation services by demand-side energy storage in electric vehicle battery swapping stations (BSS). An interaction framework, namely station-to-grid (S2G), is presented to integrate BSS energy storage into power grid for giving benefits to frequency regulation. The BSS can be regarded as a lumped battery energy storage station through S2G framework. A supplementary AGC method using demand-side BSS energy storage is developed considering the vehicle user demand of battery swapping. The effects to the AGC performance are evaluated through simulations by using a two-area interconnected power grid model with step and random load disturbance. The results show that the demand-side BSS can significantly suppress the frequency deviation and tie-line power fluctuations.

• Journal of Power Electronics
• /
• 제16권3호
• /
• pp.1200-1208
• /
• 2016

Planar electromagnetic interference (EMI) filter has significant engineering significance to power electronic system integration and miniaturization. However, the value of differential mode capacitance cannot meet the demand of noise suppression because of the size limit of ceramics. In this case, the EMI filter of novel multilayers is recommended to address this issue. A novel integrated structure of EMI filter based on multilayer ceramic is proposed in this study. The inductance and capacitance of the new structure can be designed separately, which is an advantage in manufacturing. Insertion loss is measured more closely to the actual situation in this study, which is different from the condition where source and load impedances are both 50 Ω. In the process of designing a novel EMI filter, noise impedance is considered. Moreover, the prototype is created and applied to a small switching power supply, which verifies the effectiveness of the developed EMI filter.

• Journal of Power Electronics
• /
• 제14권4호
• /
• pp.806-813
• /
• 2014

Planar electromagnetic interference (EMI) filters are widely used to restrain the conducted EMI of switching power supplies. Such filters are characterized by small size, low parasitic parameters, and better high-frequency performance than the passive discrete EMI filter. However, EMI filter performance cannot be exactly predicted by using existing methods. Therefore, this paper proposes a method to use scattering parameters (S-parameters) for the measurement of EMI filter performance. A planar EMI filter sample is established. From this sample, the relationship between S-parameters and insertion gain (IG) of EMI filter is derived. To determine the IG under different impedances, the EMI filter is theoretically calculated and practically measured. The differential structure of the near-field coupling model is also deduced, and the IG is calculated under standard impedance conditions. The calculated results and actual measurements are compared to verify the feasibility of the theory.