파장 가변 어븀 첨가 광섬유 DFB 레이저

윤홍,조규만,이상배,김상혁,최상삼,Yoon, Hong,Cho, Kyu-Man,Lee, Sang-Bae,Kim, Sang-Hyuk,Choi, Sang-Sam 한국광학회 2000 한국광학회지 Vol.11 No.6

본 논문에서는 광섬유 브래그 격자를 공진기로 사용하는 파장 가변 광섬유 DFB레이저를 구현하였다 사용된 광섬유 브래그 격자는 3cm의 $Er^{3+}$ 첨가 광섬유에 새겨졌고 브래그 공명파장은 1559.4nm이다 단일모드 동작과 낮은 문턱 펌프를 위해 UV재조사 방법을 통하여 $\lambda/4$ 위상천이를 주었다. 제작된 레이저는 $230\muW$ 파워의 단일 모드 발진을 하며 35kHz의 선폭을 갖는다. 또한 광섬유 격자를 PZT로 조절하는 광섬유 인장기로 인장하여 레이저의 발진파장을 3nm까지 가변할 수 있었다. A study of the tunable fiber DFB laser using PZT-stretcher is presented. The device has an laser ocsillator by using a fiber Bragg grating at 1559.4 nm written directly into a 3-cm long $Er^{3+}$ doped fiber. Post UV-exposure method to provide the necessary phase shift is used for a single mode operation. The device shows the single mode operation of $230\muW$ output power and has a narrow linewidth of 35 kHz. The lasing wavelength of the laser can be tuned in a range of 3 nm by stretching the grating.rating.

PZT-stretcher를 이용한 파장가변 광섬유 DFB레이져

윤홍,조규만,이상배,김상혁,최상삼,Yun, Hong,Jo, Gyu-Man,Lee, Sang-Bae,Kim, Sang-Hyeok,Choe, Sang-Sam 한국광산업진흥회 2000 광산업정보 Vol.1 No.-

광섬유 브래그 격자를 이용한 광섬유 레이저 장거리 스트레인 센서 ( Multiplexed Strain Sensor For Long-Distance Remote Sensing Using Fiber Grating-Tuned Fiber Laser Scheme )

윤홍,권서원,이상배,최상삼,김성철,강성철,이병호 한국통신학회 1998 한국통신학회 기타 간행물 Vol.- No.-

어븀 첨가 광섬유 DFB 레이저 ( Er3+ doped Fiber Distributed-Feedback ( DFB ) Laser )

윤홍,권서원,강성철,김성철,이정찬,이상배,최상삼,조규만 한국통신학회 1998 한국통신학회 기타 간행물 Vol.- No.-

난류 경계층의 Hairpin 와 구조에 대한 압력구배의 영향

윤홍,김경천 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.8

이동무선 LAN 시스템의 고속핸드오버를 위해 능동적인 유효채널탐색방식의 성능분석

윤홍,임재명,윤종호,김세한 대한전자공학회 2006 電子工學會論文誌-TC (Telecommunications) Vol.43 No.11

In this paper, we propose a new Active Channel Scanning scheme by scanning active channels employed by neighbor APs' with the handover counts and non overlap channel information for fast handover. Under the proposed scheme, the mobile which has finished handover to connect a new APsends the neighbor AP's channel information learned by itself during handover to the new AP. And then, the new AP relays the neighbor channel information to the old AP. It decides a priority by handover counts and non overlap channel information for building a Neighbor Channel Table(NCT), and also sends the table information to its associated mobile nodes, periodically . As a result, each mobile can scan only active neighbor APs' channels when performs handover based on the referring to NCT information. Using NS-2 Simulator, we applied to supposed ACS that the result of simulation decides to sort by handover counts and non overlap channel information. we evaluate our proposed ACS scheme based on NCT along with the full scanning scheme and the selective scanning scheme. From simulation results, we show that the proposed scheme is advantageous over the other two schemes in terms of the number of scanning channels and the scanning latency. 본 논문에서는 무선LAN환경에서의 신속한 핸드오버를 지원하기 위하여 핸드오버 횟수와 인접한 AP간 겹쳐지는 영역의 유무를 고려하여 주변 AP가 실제 사용하고 있는 유효채널만을 탐색하는 새로운 방식을 제안한다. 제안된 방식에서는 이동단말이 새로운 AP로의 핸드오버가 완료되면, 자신이 탐색과정에서 습득한 주변 AP의 유효 채널정보를 새로운 AP에게 보고한다. 해당 AP는 이 정보를 이전 AP에게 전달하고, 핸드오버 횟수와 인접한 AP간에 겹쳐지는 구간이 없는 셀의 정보를 고려하여 우선순위를 결정한 이전 AP는 유효채널정보를 정렬한 후, 이 채널정보를 자신에 접속된 단말들에게 주기적으로 통보한다. 이러한 절차에 의해, 기존 AP에 접속된 나머지 단말들은 자신이 핸드오버 할 경우 인접 AP가 사용하는 활성화되어 있는 채널만 탐색할 수 있기 때문에 보다 신속한 핸드오버가 가능하게 된다. NS-2 시뮬레이터를 사용하여, 핸드오버 횟수와 인접한 AP가 겹쳐지는 구간이 없는 셀의 정보를 고려한 우선순위선정 방법에 대한 모의실험을 수행하여 최적화된 우선순위방식을 제안된 유효채널탐색 방법에 적용하였다. 이 제안방식과 인접한 모든 채널을 탐색하는 기존의 full scanning 그리고, 미리 정해진 순서에 따라 일부 채널만 탐색하는 selective scanning 방식 등 3가지에 대한 성능비교를 수행한 결과, 제안된 방식이 핸드오버 과정에서 수행하는 전체 탐색채널의 개수와 채널탐색시간 면에서 우수함을 보였다.

Mask EID 기반 CAN 프로토콜 보안성 강화 방안

윤홍 국방보안연구소 2021 국방과 보안 Vol.3 No.1

Recently, interest in CAN(Controller Area Network) technology has increased as the smart car market has grown rapidly. However, the CAN protocol in the vehicle environment communicates broadcasting. And this approach has a weak security mechanism. In this paper, we generate random IDs by masking node extension IDs. Each node then uses this information (EID : Extended Identifier) to identify nodes in the local network. We propose a CAN_with_MEID&NAL(Network Access List) scheme that stores identified local node information (EID) in NAL and uses only node messages with registered EID information. This method can prepare for various cyberattacks such as retransmission attacks and unauthorized access. As a result, local network nodes can be identified each time a vehicle is driven, ensuring a safe scheme.

ECU 정보 기반 차량용 블록체인 적용 방안

윤홍,박종범 국방보안연구소 2022 국방과 보안 Vol.4 No.2

Recent studies show that the interest in the security of vehicle-network increases as the smart car market rapidly grows. The smart car controls Electronic Control Units (ECU) installed in the vehicle in order to provide fast and safe driving. Controller Area Network (CAN) is the most representative controlling method and is a message-based communication protocol that considers the specificity of the vehicle environment. However, this method has significant vulnerabilities like broadcasting, unused transmission and reception addresses and this makes CAN vulnerable to cyber attacks like DoS and re-transmission. Therefore, this paper proposes an improvement method which includes the following three factors. First, an ECU node ID is randomly generated with a common information table, also called as mask table, from each ECU node. Then, the ID generated by the ECU nodes is registered in the Network Allow List (NAL) and allows the message communication between the ECU nodes. This process enables only the messages from the nodes that have undergone the initial registration process can be used. Second, for non-repudiation of message content, the results of calculating message information, mask table, time are loaded in the message checksum and transmitted. Third, IDS & Blockchain_with_EID method, that hybrid blockchain is applied to the aforementioned ECU ID and non-repudiation of message, is proposed. This proposed method can be prepared for various cyber attacks such as DoS, re-transmission attack, and unauthorized access. Moreover, it supports stable autonomous driving and defense mechanism of cyber attacks through blockchain-based algorithms.

軍 지상기지국 네트워크 분리를 적용한 사이버 위협에 대응 방안

윤홍,김상문,조해민,류중렬,홍석우 국방보안연구소 2023 국방과 보안 Vol.5 No.1

Development of space industry in recent years has expanded battlefield from ground, air, and sea to space area. South Korea is now operating eight satellites, and the number of the satellites will be increased to 130 by 2030. Due to such a development, researches on a new way of operation of space systems will be advanced, and which will support military operations in/directly. However, security threat on the space system will also increase, inherently. In particular, it is expected an attack that leads errors on a satellite by beaming high-power frequency an attack space vehicle generates nearby, or that malfunctions a satellite by sending spoofed or exploited messages that paralysis the satellite's subsystem(power, attitude control, etc.) or moves it excessively, as will be discussed in this paper, to a ground station. In order to respond to such an attack, ground stations' control/image/tracking systems should be separated and controlled physically and logically by mission. Specifically, VPN(Virtual Private Network) is required, and the network has to be separated based on each system's information. With the proposed approach, unauthorized users can be identified. Finally, we need to specify the scope of the subsystem's operational criteria in the messages, limit the use of the messages unnecessarily issued, and identify unauthorized access and exploited message in order to operate space systems in a stable manner.

랜덤 ECU ID 기반 블록체인 활용한 차량용 네트워크 보안성 강화 방안

윤홍 한국정보처리학회 2022 정보처리학회지 Vol.29 No.4