• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.45 no.5
• /
• pp.486-492
• /
• 2012

In the late 1970s, the National Fisheries Research & Development Institute (NFRDI) started cetacean research to submit the Korean whale catch record to the International Whaling Commission. This continued until the moratorium on commercial whaling in 1986. The NFRDI resumed cetacean research with a pilot whale sighting survey in 1999. Subsequently, the NFRDI has conducted 53 cetacean sighting surveys within the Korean exclusive economic zone between 2000 and 2010. The surveys took a total of 760 days and cruising for 23,866 nautical miles. The finless porpoise Neophocaena asiaeorientalis was sighted most frequently (735 times), followed by the minke whale Balaenoptera acutorostrata (396 times), the long-beaked common dolphin Delphinus capensis (102 times), and the Pacific white-sided dolphin Lagenorhynchus obliquidens (27 times). Minke whales were distributed in the Yellow Sea and coastal area of the East Sea from spring to fall. Pacific white-sided dolphin sightings were restricted to the middle and upper coastal areas of the East Sea in summer. Common dolphins were sighted from east of the southern coast to the eastern coast of the Korean Peninsula from spring to fall. Finless porpoise occurred in all Korean coastal areas, except the middle and upper eastern coast.

• The KIPS Transactions:PartA
• /
• v.16A no.4
• /
• pp.255-262
• /
• 2009

We present an autonomous entertainment dolphin robot system based on ubiquitous sensor networks(USN). Generally, It is impossible to apply to USN and GPS in underwater bio-mimetic robots. But An Entertainment dolphin robot which presented in this paper operates on the water not underwater. Navigation of the underwater robot in a given area is based on GPS data and the acquired position information from deployed USN motes with emphasis on user interaction. Body structures, sensors and actuators, governing microcontroller boards, and swimming and interaction features are described for a typical entertainment dolphin robot. Actions of mouth-opening, tail splash or water blow through a spout hole are typical responses of interaction when touch sensors on the body detect users' demand. Dolphin robots should turn towards people who demand to interact with them, while swimming autonomously. The functions that are relevant to human-robot interaction as well as robot movement such as path control, obstacle detection and avoidance are managed by microcontrollers on the robot for autonomy. Distance errors are calibrated periodically by the known position data of the deployed USN motes.

• The Journal of the Acoustical Society of Korea
• /
• v.40 no.3
• /
• pp.219-227
• /
• 2021

This paper proposed an Orthogonal Frequency Division Multiplexing (OFDM) based biomimetic communication method using a dolphin whistle which covertly transmits communication signals to allies. The proposed method divides the dolphin whistle into several time slots corresponding to a number of OFDM symbols, and modulates the communication signal by mapping differential phase shift keying (DPSK) symbols into subcarriers that have the frequency bands of the dolphin whistle in each slot. The advantages of the proposed method are as follows: In the conventional Chirp Spread Spectrum (CSS) and Frequency Shift Keying (FSK) based biomimetic communication methods, the discontinuity of the frequency contour is large, but the proposed method can reduce the discontinuity. Even if the modulation order is increased, the degradation of the mimicking performance is small. The computer simulations demonstrate that the Bit Error Rate (BER) and mimicking performance of the proposed method are better performance than those of the conventional CSS and FSK.

• Journal of the Society of Naval Architects of Korea
• /
• v.38 no.2
• /
• pp.10-18
• /
• 2001

The very large floating structure which can be used for as airport may be as large as several kilometer long and wide. The first order wave forces as well as wave drift forces are very important forces on such a very large floating structures. In the present study, the time simulation of motion responses for dolphin-moored VLFS in waves is presented. The hydrodynamic coefficients and wave forces involved in the equations are obtained from a three-dimensional panel method in the frequency domain. The horizontal drift forces and mooring forces for dolphin systems are taken into account. As for numerical example, time domain analyses are carried out for a VLFS(Phase I) in irregular wave condition.

• Journal of Veterinary Clinics
• /
• v.33 no.2
• /
• pp.142-144
• /
• 2016

We report a case of Escherichia coli septicemia in a 6-year-old male bottlenose dolphin (Tursiops truncatus). Gross lesions included turbid reddish yellow ascites, fibrous adhesions of rectum and peritoneum, multifocal mucosal ulcers of rectum, and systemic petechiae. Multifocal necrosis with bacterial colonies was observed histologically in mucosal membrane of rectum and anus, and also in caudal mesenteric lymph node, inguinal lymph node, tracheobronchial lymph node, tonsil, spleen, liver, and lung. E. coli was isolated in pure culture from multiple organs including blood, spleen, mesenteric lymph node, liver, lung, and ascites. The E. coli was serotype O25. This case was diagnosed as a septicemia caused by E. coli serotype O25 associated with proctitis.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.37 no.3
• /
• pp.189-195
• /
• 2001

The characteristics of echolocation signals of the Common Dolphin, Delphinus Delphis was observed by the hydrophone in order to detect exactly distribution and migration on whales and dolphins in Korean Coastal waters. It's observation was carried out at the position of 13 mm off Gam-Po of Korean east-southern sea at 3rd-5th. April and 13th-15th. October, 1999. The results obtained are summarized as follows: (1) The frequency range of ship's noise and ambient noise in the observed station was 0.5-0.3 kHz, that ones could be influenced to the behavior of common dolphins which carry out echolocation using low-frequency. (2) The common dolphin was radiated single click of 8.6 ms and double click of 4.8 ms pulse width during these observation (3) The high click frequencies of common dolphin were 5.10 kHz, 7.22 kHz, 10.60 kHz with the click pulse width of 4.0 ms, 2.6 ms, 1.0 ms, respectively. In case of low-frequency 1-2 kHz, that is, 1.12 kHz, 1.38 kHz, 1.82 kHz, pulse width were 22.4 ms, 2.05 ms, 11.9 ms, respectively and they showed a tendency using triple click signal. (4) The pulse width, pulse recurrence interval and frequency range of the observed echolocation signals were 2.4-8.4 ms, 9.0-40.0 ms, 0.60-10.63 kHz respectively, and frequency spectrum level was 100-125 dB for single, double, triple click signals.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.46 no.6
• /
• pp.892-900
• /
• 2013

In 2011, the system for conserving and managing cetacean resources in Korea changed. The status of the cetacean bycatch was analyzed using a distribution certificate that was issued by the coast guard. During 2011.2012, 12 species were bycatch in Korean waters: three species of baleen whale and nine species of dolphin. The finless porpoise (Neophocaena phocaenoides) was the dominant species, followed by the common dolphin (Delphinus delphis), harbor porpoise (Phocoena phocoena), and Pacific white-sided dolphin (Lagenorhynchus obliquidens). Among the baleen whales, the common minke whale (Balaenoptera bonaerensis) was first and Bryde's (Balaenoptera edeni) and humpback (Megaptera novaeangliae) whales appeared in the Korea Strait and East Sea, respectively. Among the dolphins, the finless porpoise ranked first in the Yellow Sea. The common dolphin, Pacific white-sided dolphin, and harbor porpoise were more frequent in the East Sea than in other waters. The cetacean bycatch was caused mainly by pots, set nets, gill nets, and stow nets. Among the three species of baleen whale, the common minke whale was caught by pots and set nets, and comprised over 68.9% of the total bycatch in 2011 and 56.2% in 2012. Comparing the bycatch caused by fishing gears by area in 2011 and 2012, 97.9% and 99.6%, respectively, of the finless porpoise bycatch in the Yellow Sea was by stow nets. In the Korea Strait, trawl bycatch comprised 67.3% in 2011 and 73.0% in 2012, followed by gill nets, set nets, and pots targeting finless porpoise and common minke whales. In the East Sea, gill nets were responsible for 46.7% in 2011 and 61.2% in 2012, followed by set nets and pots.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.12 no.2
• /
• pp.48-48
• /
• 1976

• Journal of Electrical Engineering and Technology
• /
• v.6 no.1
• /
• pp.81-85
• /
• 2011

The end effect of a linear induction motor (LIM) has been known for several decades, especially in high speed operation. The exit part of the primary is not dealt as extensively as the entry part because of its minor effect. However, the exit part is one of the keys to weaken the dolphin effect, which occurs in high speed operation. In this paper, the concept of the virtual primary core is introduced, and chamfering of the primary outlet teeth is proposed to minimize the longitudinal end effect at the exit zone. For this, LIM for the high-speed train is designed and analyzed by using finite element method. Results confirm that chamfering can improve thrust performance effectively.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
• /
• 2001.10a
• /
• pp.239-242
• /
• 2001