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백칠기,백칠기 해군대학 1990 海洋戰略 Vol.- No.68
이 글은 서독 해군 잠수함 전단의 작전장교인 H. Boehm 이 최초 <Naval Forces>, No. IV(1986)에 게재한 것을 <The Submarine Revies>, July 에 재차 실렸던 글을 번역한 것임 I. 서언 II. 천해(Shallow Waters) III. 천해조건의 효과들 IV. 작전원칙 V. 결론
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백칠기,장지원 한국음향학회 1993 韓國音響學會誌 Vol.12 No.6
1986년 미국 음향학회 수중음향학술분과 특별회기중에 제안된 표준쐐기형 매질내의 음장을 계산하기 위하여 영상모델이 사용되었다. 음장의 계산 결과는 왕복결합모드무델과 음선모델에 의한 계산 결과들과 비교되었다. 영상모델은 그 특성에 의한 제한점을 갖고 있으나, 표준 쐐기형 매질의 음장 계산에 사용될 수 있고, 기존의 수치모델과는 달리 개인용 컴퓨터로써 쐐기형 매질의 음장 계산이 가능하기 때문에 음파 전파 현상분석 등의 연구에 유용하게 사용될 수 있다.
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白七起 ( Beck Chil-ki ) 해군사관학교 해양연구소 1995 해양과학기술 Vol.14 No.0
This paper proposes the methods of generating the beam patterns relevant to the array utilizing purpose and important items for the effective ways of the array use through the results of analyzing the field's characteristics which can be seen from the calculated results of the acoustic field of a line array with respect to the range, the characteristics of a line array structure and the properties of a line array element's source.
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白七起 ( Beck Chil-ki ) 해군사관학교 해양연구소 2000 해양과학기술 Vol.24 No.0
This research is a study on design variables of a passive sound amplifier that is in its 3rd year following a basic study of the 1st and 2nd year of the 1st stage of a unique project titled as The Development of Highly Efficient Sound Reflective Amplification Type Passive Sonar System. The two variables which are the signal frequency band and the detection range are required for the design of the parabolic sound reflective amplifier. Therefore in order to have a sound amplifier design that satisfies these two requirements, we have to know in advance the relations between the detection range of the passive sonar, the frequency band of the target, and the transmission loss of the sea areas that a sonar Is deployed. In general, the detection range of a passive sonar depends on SL(Source Level), TL(Transmission Loss). NL(Noise Level). DI(Directivity Index). DT(Detection Threshold). PD(Probability of Detection). PFA(Probability of False Alarm), and the depths of the sound source and the receiver. The study presented the method of the most effective design of the reflective sound amplifier by computing the detection range which depends on the directivity index that is computed from the beam patterns which depend on the size of the parabolic sound reflective amplifier when a sound wave spreads cylindrically in an absorptive homogeneous medium. Moreover, the mutual relations between the frequency band of a target, the detection range of a passive sonar, and the sound transmission loss required for the design of the parabolic sound reflective amplifier are presented. The sound transmission loss of the sea, which is necessary for design of the sound reflective amplifier is calculated by the developed model based on the model of cylindrical spreading in an absorptive homogeneous medium. The detection ranges are computed with PD with the assumption of 50%, DI from the size of the reflection amplifier. TL from the developed cylindrical spreading model, and with the assumed values of SL, NL. DT. and sound source frequency that are similar to the values of real ocean acoustic environment and sonar parameters. The optimum design of the reflective sound amplifier has been carried out as follows. The proper size of the reflective sound amplifier in relation to the detection range was determined by deriving the relation between the size of the reflective sound amplifier and the directivity index, which can be found by using the relation between beam patterns and the directivity index, and dy deriving the relation between the size of the parabolic sound reflective amplifier and beam patterns
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白七起 ( Beck Chil-ki ) 해군사관학교 해양연구소 1998 해양과학기술 Vol.20 No.0
This research is the 1st year of unique project entitled as “Development of highly efficient sound reflective amplification type passive SONAR system, on the subject of A pilot research on sound reflective amplifier in air” research was carried out. A sound reflector of three dimensional parabolic structure was made, and signal amplification ratio and the beam pattern of sound reflective amplifier were measured, and the characteristics of sound reflector were understood by making a comparison between calculated value by the numerical model that can predict the beam pattern and measurements. Calculated value of the reflector amplification ratio 104 and measured value 107 were the same with each other, but the values of 3dB down beam width between calculated and measured value were different as 1.7˚. And we can see that this sound reflector can be a core element of passive SONAR system in composition of an effective underwater monitoring system for Korea through the results of research of parabolic sound reflector's acoustic energy amplification ratio and beam pattern.
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강성욱,홍우영,송영일,류기상,백칠기,Kang, Sung-Oug,Hong, Woo-Young,Song, Yeong-Il,Lyu, Ki-Sang,Baek, Chil-Ki 한국음향학회 1997 韓國音響學會誌 Vol.16 No.3
쐐기각이 다른 4종류의 쐐기형 수중음파 흡수타일을 설계, 제작하고 각각의 흡음타일에 대한 반사음장의 크기를 측정하였다. 흡음타일의 정면에서 측정한 반사음장의 크기는 실험한 4개의 타일중 쐐기의 꼭지각이 30$^{\circ}$일 때 최소값을 갖고 120$^{\circ}$일 때 최대값을 가졌다. 쐐기형 흡음타일의 꼭지각이 클수록 그 반사계수가 증가되는 것을 확인하였다. 또한 본 실험에 사용된 10kHz~30kHz 주파수 범위에서 쐐기각이 같은 흡음판에 의한 반사음장의 크기는 주파수와 무관하였다. 그리고 쐐기형 흡음타일 후면에서 측정한 반사음장의 크기는 흡음판의 형태와 실험에 사용된 주파수들에 무관한 일정한 값을 가졌다. 쐐기형 흡음타일의 반사음장에 대한 측정값과 수치모델에 의한 계산값은 대체로 잘 일치하였다. Four different wedge angle absorptive tiles were designed and made, and the magnitudes of the reflected acoustic fields by the wedge shaped underwater sound absorptive tiles were measured. The minimum magnitude was found at the angle of 30$^{\circ}$ and the maximum of it was found at the wedge angle of 120$^{\circ}$ from measured the reflected acoustic fields at the front sides of the tiles. The fact that as wedge angle of the absorptive tile increases, the reflection coefficient is increasing is verified. The measured reflected acoustic fields were not dependent on the frequency in the range of 10kHz~30kHz used in this experiment for the same wedge angle tile. The measured reflected acoustic fields at the back sides of the tiles show that they are independent from both type of the absorptive tiles and the frequencies used in the experiments. The measured values and the computed values by the numerical model for the reflected acoustic fields of the wedge shaped absorptive tiles are fairly well comparable with one another.
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