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CW 신호를 사용하는 수중 음원의 위치 추정에 관한 연구
박원철(Won-Chul Park),권경엽(Kyoung-Youb Kwon),정구락(Koo-Rack Chung),홍영기(Young-Ki Hong),변승우(Seung-Woo Byun) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6
It is well known fact that acoustic positioning systems are absolutely needed for various underwater operations. According to the distances between their sensors they are classified into three parts: long baseline(LBL), short baseline(SBL), and ultra-short baseline(USBL). There are many techniques for underwater source localization. These are the methods based on TDOA(Time Difference Of Arrival) estimation, beamforming techniques and high resolution technique, etc. In this paper we calculate TOA(Time Of Arrival) using MFFT(Modified Fast Fourier Transform) analysis that is used estimation of TOA(Time Of Arrival) in the region of frequency under CW signal. We propose the method of distance using Max-Index algorithm in order to estimate the position of underwater source for CW signal. The performance of the proposed method was analyzed under various water tank environment.
박현 ( Hyun Park ),가강현 ( Kang Hyeon Ka ),허태철 ( Tae Chul Hur ),홍용표 ( Yong Pyo Hong ),박원철 ( Won Chull Bak ),여운홍 ( Uoon Hong Yeo ) 한국산림과학회 2004 한국산림과학회지 Vol.93 No.5
This study was conducted to figure out whether Pinus rigida stand can produce a fruiting body of Tricholoma matsutake(pine-mushroom), which requires specific symbionts for survival, or not. The study site was located in Sancheong, Kyeongsangnam-do, Korea. We conducted timber cruise to figure out the circumstances of the stand, investigation of pine-mushroom production within each fairy-ring, identification of tree species by the roots collected from the fairy-rings using PCR-RFLP technique. The pine-mushroom was produced continuously from 1999 to 2003, and the productive area was about 0.111a. In this stand, Pinus rigida were planted in 1970 after harvesting of P. densiflora, which was showing about 3,000 trees/ha of stand density with average height and DBH as 7m and 12.5cm, respectively. The average diameter of the fairy-ring was 2.5m, which made us to infer the formation of fairy-ring was initiated during early 1990s with considering the annual growth rate of the fairy-ring of T. matsutake as 10cm/year. The mycorrhizal roots collected from the fairy-ring of T. matsutake was mixed with the roots of P. dens{flora and those of P. rigida with the portion of 38.3%(23/60) and 61.7%(37/60), respectively. The whole roots collected from a certain plot were identified as the roots of P. rigida. This phenomenon may indicate that P. rigida alone can produce the pine-mushroom. The observation is the fnst report on the production of fruiting body of T. matsutake in a P. rigida stand in the world, which indicate that P. rigida can serve as a symbiont of T. matsutake. The result gives a good opportunity to reevaluate the value of P. rigida that had been planted widely for greening of denuded forest.