• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.220-222
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• 2000

이동통신 시스템에서 가입자수가 증가하고 다양한 서비스가 구현됨으로써 전체적인 장비 또는 자원에 대한 부하가 증가하고 있다. 특히, 셀의 반경이 작아지고 단문(Short Message)을 활용한 다양한 부가 서비스가 개발됨으로써 이와 관련된 정보를 전달하는 페이징 메시지의 분류도 복잡해지고 페이징 채널의 부하도 커지고 있다. 본 연구에서는 먼저, 이동통신시스템에서 페이징 패널의 구조와 역할을 분석하고 페이징 채널에서 전송하는 메시지를 그 기능과 특성에 따라 분류한다. 긴급하게 전송되어야 하는 메시지를 보호하기 위한 우선권 부여 방법을 모색하고, 각 방법에 있어서 메시지 종류별 전송지연시간(Delay)을 수리적으로 도출하고 결과를 비교한다.

• The Journal of the Acoustical Society of Korea
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• v.17 no.3
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• pp.65-71
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• 1998

비균등 에러 보호에 의한 IMT-2000용 CDMA 순방향 링크의 성능개선 방법을 나타 내었다. 제안된 방법의 성능은 다경로 페이딩채널 및 BPSK변조에 대한 CS-ACELP 음성부 호화기 및 RCPC 채널부호화기를 이용하여 분석되었다. CS-ACELP 부호화기의 비트 에러 감도 정보에 근거한 연계성능분석 결과제안된 방법은 SEGSNR이 0.4∼1dB 개선되었다. 또 한 총전송율 및 전력제어비트를 펑처링하지 않고도 기존 구조를 유연성있게 변경 가능하다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.173-175
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• 2011

적극적인 관제 및 책임 관제구역 도입의 필요성과 안전항행을 위한 정보제공 및 업무 효율성 증진 방안 강구로 현재 섹터 관제를 시행하고 있으며 선박의 충돌사고 예방 및 해양환경보호에 큰 역할을 하고 있는 것이 사실이다. 하지만 일반적 형태와 상이한 부산항의 관제섹터 변경구역에서의 현 문제점과 합리적인 VHF채널 운영방안을 제시한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.6
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• pp.1037-1044
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• 2014

A (t,n) threshold secret sharing scheme is the scheme which allows a trusted party to distribute the shares among n participants in such a way that any t of them can recover the original secret, but any group knowing only t-1 or fewer shares can not. Recently, Eslami et al. and Tadayon et al. proposed threshold multi-secret sharing schemes, respectively. They proposed that their schemes don't require secure channels. But, without secure channels in their schemes, everyone can get the shares and find the secrets. The proposed scheme does not use secure channels and only t participants can solve the equations of the system from the delivered share shadows and find the secrets.

• Journal of Broadcast Engineering
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• v.16 no.3
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• pp.490-500
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• 2011

The channels of domestic FM broadcast are needed to provide various kinds of new broadcasting services. However, available channels are limited and saturated. The channel interval of FM broadcast is changed from 200 kHz to 100 kHz to maximize utilization efficiency of scarce broadcast spectrum at all over the world. Also, there are many researches such as IBOC(In Band On Channel) and DRM+(Digital Radio Mondial+) that is to allocate the digital signal beside analog bandwidth. But output power is decrease to avoid interference between adjacent radio stations. In this paper, we analyzes the problems of the protection ratio which is decided in 1986 and we propose method to improve about 7~10dB significantly the protection ratio according to the recent DSP(Digital Signal Processing) techniques without loss of both transmission power and broadcast quality. In addition, we examined the possibility of securing two times available channels by reducing minimum frequency interval from 800 kHz to 400 kHz or 600 kHz in the equal site.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.3
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• pp.77-86
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• 2006

As a core technology in the ubiquitous environment, RFID (Radio Frequency Identification) technology takes an important role. RFID technology provides various information about objects or surrounding environment by attaching a small electronic tag on the object, thus, it means the remote control recognition technology. However, the problems which never happened before can be generated on the point of security and privacy due to the feature that RFID technology can recognize the object without any physical contact. In order to solve these problems, many studies for the RFID recognition technology are going on the progress. The currently running study is the secure communication channel between database and reader applying the recognition technology in the insecure communication channel between reader and tag. But, the purpose of this paper is to settle a privacy problem, which is insecurity of communication between database and reader channel by suggesting providing a user with authentication protocol in order to give information to an authorized entity.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.4
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• pp.59-68
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• 2006

Although the cryptographic algorithms in IC chip such as smart card are secure against mathematical analysis attack, they are susceptible to side channel attacks in real implementation. In this paper, we analyze the security of smart card using a developed experimental tool which can perform power analysis attacks and fault insertion attacks. As a result, raw smart card implemented SEED and ARIA without any countermeasure is vulnerable against differential power analysis(DPA) attack. However, in fault attack about voltage and clock on RSA with CRT, the card is secure due to its physical countermeasures.

• Journal of Internet Computing and Services
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• v.16 no.6
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• pp.1-9
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• 2015

In this paper, we study the coexistence of typical radio access technologies (WiMAX, CDMA, WLAN) in heterogeneous networks. Although the radio accesses employ different frequency band, they can interfere with each other due to out-of- band emission. We compute the minimum adjacent channel interference ratio (ACIR) to satisfy the allowable level of interference, and the resulting minimum frequency separation (guard band) between interfering and victim system. We observe that WiMAX-WLAN coexistence and WiMAX-CDMA coexistence are feasible with at least 20 MHz and 15 MHz guard bands, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1104-1111
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• 2012

Airborne tactical networks is used to air-to-air or air-to-ground operation and have a large propagation delay. All nodes share the data by using TDMA-based broadcasting. In airborne tactical networks, each time slot needs the guard time to ensure the broadcasting because the collisions occur due to the large propagation delay. However, the channel utilization of the networks can be greatly degraded due to the waste of guard time. In this paper, we propose Inter-Transmitter Distance-Based TDMA (ID-TDMA) scheme which ensures the broadcasting while improving the channel utilization by reducing the guard time with the inter-transmitter distance information. The proposed scheme shows the effectiveness through the performance evaluation.

• Journal of the Korea Convergence Society
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• v.5 no.4
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• pp.101-106
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• 2014

Most peoples are used to prefer to view the video contents rather than the other contents since the video contents are more easy to understand with both their eyes and ears. As the wide spread use of smartphones, the demands for the contents services are increasing rapidly. To promote the contents business, it's important to provide security of subscriber authentication and corresponding communication channels through which the contents are delivered. Generally, symmetric key encryption scheme is used to protect the contents in the channel, and the session key should be upadated periodically for the security reasons. In addition, to protect viewing paid contents by illegal users, the proxy authentication should not be allowed. In this paper, we propose biometric based user authentication and one time key generation models. The proposed model is consist of biometric template registration, session key generation and chanel encryption steps. We analyze the difference and benefits of our model with existing CAS models which are made for CATV contents protection, and also provides applications of our model in electronic commerce area.