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TRS 상의 개별/그룹 통신을 위한 효율적인 키 분배 기법
이덕규,박용석,안정철,이임영,Lee, Deok-Gyu,Park, Yong-Suk,Ahn, Jong-Chul,Lee, Im-Yeong 한국정보처리학회 2006 정보처리학회논문지 C : 정보통신,정보보안 Vol.13 No.7
주파수공용통신(TRS: Trunked Radio Service)이란 무선통신을 하는 사람이 특정한 주파수를 이용하던 종래의 무선통신방식과는 달리 중계소에 할당된 소수의 주파수를 다수의 이용자가 공동으로 사용하는 방식을 말한다. TRS 시스템의 가장 큰 특징은 일대 다수의 그룹 및 지령 통신방식이다. TRS 시스템의 구성은 여러 개의 그룹으로 구성되며, 각 그룹은 업무내용에 관련된 유사한 목적을 가진 사용자들의 단말기로 구성된다. 위와 같은 여러 목적에 따라 다양한 형태의 연결이나 그룹 통신이 이뤄질 경우, 여러 가지 형태의 공격에 노출될 수 있으며, 대규모 통신을 위한 키 분배 혹은 설정에 많은 문제점을 가질 수 있다. 본고에서는 TRS 상에서 안전한.통신을 수행하는데 있어 필수 요소인 그룹 키 분배방식을 고찰하며, 통신 횟수를 줄이면서도 참여자 인증을 수행할 수 있는 효율적인 그룹 키 분배 방식을 제안하였다. It used exclusively the radio communication where is the TRS(Trunked Radio Service) at frequency where the person whom it does is specific with hitherto radio communication method differently frequency of the decimal which is allocated to the relay station it talks the at the room which the multiple user uses with commonness. The TRS system the most big feature is the region multiple group and order communication method. The TRS the composition of system is composed of the multi mind group, the each group is composed of the terminal of the users who have the objective which is similar relates in business contents. With above it follows in same multi objective and the connection of the form which is various or group communication accomplishes and quality case, a possibility a or of having many problem point in key distribution for a large scale communication there is it could be exposed to attack of the form which is various. There is a place where it accomplishes the communication which is safe at the TRS from research which it sees it investigates group key distribution method which is an essential element. The method which it sees when it reduces a communication frequency, it stands but is the user, it proposes the efficient group key distribution method it will be able to accomplish.
광대역소음 부하 후 이음향방사의 변화와 일시역치변동과의 관계
이덕규,이재은,고의경,이일우,공수근,전경명 대한이비인후과학회 2010 대한이비인후과학회지 두경부외과학 Vol.53 No.3
Background and ObjectivesZZA distortion product otoacoustic emission (DPOAE) is a noninvasive method which is commonly used to assess the hearing function of the cochlea and to reflect objective information of specific frequency in the cochlea. We hypothesize that after applying a broad band noise (BBN), the outer hair cell’s function will change and cause reduction in the amplitude of DPOAEs and signal to noise ratio (SNR). Subjects and MethodZZWe performed the examination on 40 subjects (80 ears) who have a normal hearing function. DPOAEs were recorded before and after BBN stimulation (intensity: 90dB HL, duration: 10 minutes). ResultsZZAfter the BBN stimulation, the amplitude of DPOAEs and SNR were decreased at all frequencies. The amplitude of DPOAEs and SNR decreased 0.3-1.6 dB SPL, 0.6-1.5 dB SPL,respectively. Decreases in the amplitude had statistical significances after 3 and 6 minutes in 1kHz, 3 and 6 minutes in 2 kHz, immediately after noise exposure, and after 3 and 6 minutes in 6kHz. However, the SNR changes had statistical significance only after 3 minutes in 1 kHz. After the stimulation, pure tone threshold at 4 kHz increased 3.2±3.9 dB HL. After the BBN exposure,the amplitude of DPOAEs and SNR decreased at all frequencies and most of them recovered within 12 minutes. ConclusionZZThese results suggest that DPOAE could be a clinically useful method for the purpose of screening, managing and assessing the prognosis of acoustic trauma and noise induced sensorineural hearing loss. Korean J Otorhinolaryngol-Head Neck Surg 2010;53:143-7