• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.527-528
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• 2012

DBD (Dielectric Barrier Discharge) plasma actuator was designed for aerodynamic drag reduction using plasma flow control, and the drag reduction was measured by wind-tunnel tests using 2D test model. At the zero wind velocity, the plasma flow control had no effect on the drag reduction because the flow separation and surface friction drag were not occurred. At the wind velocity of 2m/s, 9.7% of drag was reduced by the flow separation control. The drag reduction decreased as the wind velocity increased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.290-293
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• 2012

The analysis and performance evaluation of DBD actuator for plasma flow control was described. The experimental apparatus was designed to measure the flow velocity as the discharge conditions, and to find out the optimal discharge condition of the DBD actuator. The average-velocity increased with increasing the discharge voltage. The experimental results was compared with CFD analysis.

• Korean Journal of Ichthyology
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• v.32 no.1
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• pp.8-13
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• 2020

The feeding habits of oriental bonito (Sarda orientalis) were studied using 288 specimens collected in the coastal waters of Jeju Island, Korea from January to December 2015. Oriental bonito is pelagic piscivore that consumes mainly fishes especially Engraulis japonicus and Scomber japonicus. Its diet also includes small quantities euphausiids, amphipods and cephalopods. Oriental bonito showed ontogenetic changes in feeding habits. Although fishes were the primary food consumed by all size groups, the ratio of fishes was slightly increased as body size increase. There also was a significant relationships between mean prey number and weight according to size class and season.

• Environmental Analysis Health and Toxicology
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• v.20 no.4 s.51
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• pp.359-363
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• 2005

ESS (Embryo and sac-try stage) 독성 시험에서 시험어종으로서의 국내토착종인 왜몰개 (Aphyocypris chinensis)의 적용성을 평가하기 위하여 아연(Zn)을 사용하여 국제적인 추천시험 어종인 송사리(Oryzais latipes)와 감수성을 비교하였다. 시험기간은 대조군에서 아사가 관찰되는 시기 즉, 왜몰개는 수정 후 8일, 송사리는 수정 후 16일로 하였으며, 시험기간 동안 수정란의 부화율, 수정란 및 난황단계의 치어(sar-fry)의 사망률, 형태적인 발달, 치어의 성장 등을 관찰 및 측정하였다. 두 종 모두 수정란의 생존율에 아연의 영향을 받았으며, LOEC는 모두 14.5 mg/L이었다 난황단계 치어의 사망률을 관찰한 결과, 왜몰개는 1.4mg/L부터 급격히 증가된 반면에 송사리는 14.5mg/L에서 $100\%$사망률이 관찰되었다. 시험물질에 노출된 왜몰개와 송사리 모두 척추변형이 관찰되었으며, 체장을 측정한 결과는 왜몰개가 송사리에 비해 민감하게 반응하는 것으로 나타났다. 위와 같은 결과들은 종합해 볼 때, ESS독성시험에서 왜몰개가 대체 시험어종으로서 사용될 수 있는 가능성을 보여주었다

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.1
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• pp.21-30
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• 1991

The estimation of the fish biomass density or the size of fish by means of the acoustic equipment is an important part in the quantitative assessment of fisheries resources. The precision of such estimates depend upon the target strength of fish and the accuracy to which the acoustic equipment has been calibrated. This paper examine the accuracy of the digital measurement system which is manufactured by way of trial in order to masure the target strength of fish, and calibrations of that system carry out with an ogive and a ellipsoid made of the aluminum and the epoxy, respectively. Furthermore, measurements of target strength for eight species of fish are made at 25, 50, 100 kHz. The accuracy of the digital measurement system is compared the theory with measurements on ogive and ellipsoid, and the agreement is reasonable. Result of establishments on the target strength to fish length and to fish weight regression obtained from the measurements are available to provide the methods of design for use in interpreting acoustic measurements of fish abundance on the experimented eight species.

• Journal of Animal Science and Technology
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• v.47 no.5
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• pp.891-898
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• 2005

The trunk and limb of the Jindo, Korean native dog was measured in the present study. One hundred and ninety five Jindoes were randomly selected from the 1,985 dogs in the Jindo County in August 1998, which were screened by the judging committee of the County and registered by inserting electronic chips in the withers. They were about a year and half old, and were white and fawn dogs. A total of 18 parts of the trunk and limb were measured using calipers and tapes. The average height at the withers was 50.67 cm in dogs and 47.48 cm in bitches. The average body length was 52.99 cm in dogs and 50.33 cm in bitches. And the average height : body length ratio was 104.70 in dogs and 106.08 in bitches. No differences were observed between the Jindoes of the two coat colors in these measurements. The results of this study would be useful for compiling the official standard for the adult Jindo.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.4
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• pp.228-232
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• 1970

From the standpoint of fishery science it is an interesting matter to note that the size of Plecoglessus altivelis population on Cheju Island is smaller than that of the Nakdong River located in the southern part of Korea's mainland. Therefore the author carried out a comparative analysis to determine whether the populations differ because of racial or because of environmental conditions. The morphometric characters of the head length and the body length were used for the analysis of covariance and computed by a standard regression method of testing for the homogeneity of the populations. All samples were collected during 1968 and 1969 in the Milyang Stream of the Nakdong River and the Cheonji Stream of Cheju Island. The results of the analysis of the populations based on the significance test are as follows: 1. Since the F value observed was only 1.023 ($n_1=1,\;n_2=42$) the conclusion was reached that the samples could both belong to the same population. 2. In comparison with the deviations of the regression coefficients between the fish of the Nakdong River and Cherinji Stream, the populations were also highly significant suggesting that thelr belong to the same population. 3. The conclusion is that the fish of Cheju Island became a smaller fish in size due to an environmental condition but not due to racial characteristics.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.2
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• pp.161-169
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• 1999

This paper describes the swimming and escaping behavior of amber fish, Seriola aureovittata released in the first bag net of the setnet and observed with telemetry techniques. The setnet used in experiment is composed of a leader, a fish court with a flying net and two bag nets having ramp net. The behavior of the fish attached an ultrasonic depth pinger of 50 KHz is observed using a prototype LBL fish tracking system. The 3-D underwater position ofthe fish is calculated by hyperbolic method with three channels of receiver and the depth of pinger. The results obtained are as follows: 1. The fish released on the sea surface was escaped down to 15 m depth and rised up to near the sea surface during 5 minutes after release. The average swimming speed of the fish during this time was 0.87 m/sec. 2. The swimming speed of the fish is decreased slowly in relation to the time elapsed and the fish showed some escaping behavior forward to the fish court staying 1 to 7 m depth layer near the ramp net. The average speed of the fish during this time was 0.52 m/sec. 3. During 25 minutes after beginning of hauling net, the fish showed a faster swimming speed than before hauling and an escaping behavior repeatedly from the first ramp net to the second one in horizontal. In vertical, the fish moved up and down between the sea surface and 20 m depth. After this time, the fish showed the escaping behavior forward to fish court after come back to the first ramp net in spite of the hauling was continued. It is found that the fish was escaped from the first ramp net to the fish court while the hauling was carried out. The average speed of the fish after beginning of hauling was 0.72 m/sec which increased 38.5 ％ than right before the hauling and showed 0.44 to 0.82 m/see of speed till escaping the first bag net. The average swimming speed during observation was 0.67 m/sec (2.2 times of body length).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.6
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• pp.492-498
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• 2012

Characteristics of DBD(Dielectric Barrier Discharge) plasma actuator as design parameters were investigated for plasma flow control. Flow velocity and power consumption of the DBD plasma actuator were measured according to the design parameters such as discharge voltage and frequency, gap, width and length of electrode, and the thickness of dielectric barrier. The flow velocity and power consumption increased as the discharge voltage and frequency increased. As the electrode gap increased, the flow velocity increased with decreasing the power consumption, whereas high voltage was required for the plasma discharge. The flow velocity increased as the upper-electrode width decreased, and as the lower-electrode width increased at the constant power consumption. The performance of the DBD plasma actuator can be estimated at the given discharge and geometry conditions.

• Korean Journal of Ichthyology
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• v.13 no.1
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• pp.6-18
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• 2001

Larvae of the gunnel Pholis fangi were collected in coastal waters off Daecheon with a bag net from March to June, 1988, and with a ring larva net in February 1989. Maturity and spawning period were analyzed by examination of the gonads of adult fish collected with a bag net from May 1998 through November 1999. In February, the larvae were widely distributed in the outer and inner Cheonsu Bay. From March to April the larvae were present mainly the inner bay; they were absent there in May and found mainly in the outer bay. After June, few gunnel larvae were collected in the study area. This suggests a seaward movement of gunnel from the nursery grounds of the bay to offshore feeding grounds. The otolith of larvae smaller than 10 mm in total length did not show a distinct growth stop. The growth stop is believed to be formed in the early larval stage when the total length is about 10 mm. This period coincides with the time of shoreward migration, suggesting a metabolic change during this period. At a total length of 30 to 40 mm, the shape of the otolith changes from spherical to elongate. Daily growth rate in length was estimated by the Gompertz equation, which is represented as follows: TL = 6.702exp{2.925"1-exp (-0.008 t)"} ($r^2=0.94$, N = 92) Assuming daily deposition of growth increments in the otolith, the time of first growth increment formation was shown to be from December to January. Gonad observations show that Pholis fangi spawns from November to December. So, the hatching time is thought to be about one month.