• 수산해양기술연구
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• 제26권4호
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• pp.333-340
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• 1990

평판형과 만곡형전개판 주위에서의 유체특성을 파악하기 위하여 회유수조에서 수조기포법에 의한 하시화실험을 유속 0.05 및 0.1m/sec, 영각과 타임라인에 대해서 실시하였다. 그 결과를 요약하면 다음과 같다. 1. 만곡형전개판에서의 유선은 영각 20。까지는 균일한 분포를 이루다가 영각 25。에서 후면에 인접한 유선이 익현장의 1/2지점에서부터 작은 과가 발생되기 시작하고, 영각 30。에서는 익현자의 1.3지접에서 박리가 시작되며 인접한 유선은 전개판의 후면쪽으로 휘어들어가고, 그리고 영각 35。이상에서는 전연에서부터 박리가 시작되며 영각이 증가할수록 박리층이 증가하는 것으로 나타났다. 2. 평판형전개판에서는 영각 20。부터 전연에서 과와 박리가 발생하며, 박리층은 만곡형과 마찬가지로 영각에 비례하는 것으로 나타났다. 3. 후연에서 발생한 과의 크기가 전연의 것보다 약 2~3배 큰 것으로 나타났다. 4. 전개판의 후연에서 유선은 양 전개판 모두 전개판의 방향과 같은 방향으로 흐르다가 점차 유체흐름과 같은 방향이 되는 것으로 나타났다. 5. 전개판 전후면에서의 유속차는 영각 0。~30。에서 점차 증가하다가 영각 35。이상에서는 그 차가 비슷하게 나타났다. 6. 영각 20~30。에서 전후면의 유속차는 만곡형의 경우 후면의 유속이 전면보다 약 1.4~1.5배 빠르게 나타났으며, 평판형은 약 1.2배 빠르게 나타났다.

• 한국환경과학회지
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• 제26권12호
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• pp.1341-1353
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• 2017

This study aimed to identify the aquatic and riparian factors associated with the presence/absence of the Eurasian otter in the Nakdong river basin, where the species is relatively more abundant than other otter species. Environmental factors and presence records were collected. Geographical Information System technology and chi-square test were used to compare environmental gradients in aquatic and riparian factors between presence and absence sites. Aquatic habitat attributes were evaluated with natural riverside sandbars and channel crossing artificial structures, the ratio of channel width to alluvial plain width, riverbed substrate, and flow diversity. Riverbank characteristics, bank materials, man-made embankment types, and land use/land cover of inland and riverside areas were selected as riparian habitat attributes. Compared to the aquatic attributes, riparian attributes were highly significant when assessing otter presence and absence sites, suggesting that conservation of suitable riparian areas to provide maternity and resting areas for otter species is essential in the Nakdong river basin. None of the aquatic attributes examined were statistically significant when evaluating otter presence or absence. These results indicate that the presence of suitable riparian area for resting and reproduction habitats is more critical to the presence of Eurasian otter than food availability in aquatic areas. To inform implementation of effective conservation actions, broad-scale factors, such as watershed attributes, would be needed to further assess habitat conditions of the Eurasian otter.

• 수산해양기술연구
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• 제22권4호
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• pp.49-55
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• 1986

The authors carried out an experiment to determine the horizontal opening of the mid water trawl gear, which is the same as was used in the foreward experiment concerned to the attitude and opening efficiency of otter board. The trawl net .used in the experiment was designed to have a square sectional four-seamed body with two three-sepenlted wings. Each wing tip was rigged with a net pendant of 70 m long and the fore ends of the pendants were directly jointed to the otter pendant without inserting hand rope, and a front weight of 200 kg weigh was rigged with in front of the lowest wing tip. To determine the opening between otter boards ani between wing tips, two 50 KHz fish finders were set sideways on the otter board and on the port middle wing tip so as to detect the distance froa the finders to the starboard otter board and to the wing tip respectively, and the informations were transmitted to the indicators onboard the ship through water-tight cables. The results obtained can be summarized as follows: 1. The openings between otter borads were 43-45 m in case of the warp 100 m, 53-55 m in the war;> 150 m and 54-59 m in the warp 200 m. It was increased in linear according to the increase of towin; speed in the range of 1. 1-1. 8 mlscc. 2. The determined values of the openings between otter boards were greater than the estimated values. which were calculated by the opening between warps at the gallows of the ship and the length of tt~ warp, assuming that the warps from the top rollers to the otter boards were straight. The rates of the determined values to the estimated values were 1. 23-11. 0 in case of the warp 100 m, 1. 23-1. 12 in the warp 150 m and 1. 23-1. 15 in the warp 200 m respectively. The rates were almost the same at the slow towing speed of 1. 3 mlscc or so, then the higher the speed, the less the rate, and the longer the warp, the greater the rate. 3. The rates of the openings between otter boards to the total length of net pendant and the net (excluded cod end) showed 43-43% in case of the warp 150-200 m. It was a little smaller than th~ standard. which is 50%. in the common bottom trawl. 4. The determined openings between wing tips were 18-19 m in case of the warp 100m, 21-22 m in the warp 150 rn, They showed that the higher the speed, the greater the openings even though its range was no more than 1 m or so. 5. The rates of openings between otter boards to th~ openings betwee:l wing tips were almost invariably 38%. 6. The rates of openigs b2tween otter boards to the lenth of h~ad rope were 60-65% in cas': of th~ warp lOa-150m. It were much larg2r than th~ standard. which is 50%. in the common botto:n trawl.

• 수산해양기술연구
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• 제41권2호
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• pp.113-121
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• 2005

How to extimate the angle of attack of a vertical V-type cambered otter board was described. A three-dimensional semi-analytic treatment of a towing cable system was applied to the field experiments of a midwater trawl obtained by the Scanmar system. Also the equilibrium condition of the horizontal component and vertical component of forces and moment around the otter board was used. When the warp length was 300m long and the towing speed was between 2.61 and 3.86 knots, the estimated angle of attack of the otter board was ranged between $24.7^{\circ}$ and $26.2^{\circ}$, though the maximum lift force was at the angle of attack $22^{\circ}$.

• 수산해양기술연구
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• 제27권4호
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• pp.286-292
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• 1991

현재 사용되고 있는 전개판의 성능을 보다 향상시키기 위한 방안으로 비행기의 익이론에 기초를 두고, 전개판의 경계층을 흡입하거나 제거하는 방법 중에서 역류역을 제거하는 와발생기의 부착을 전개판에 적용하였다. 성능분석을 위해서 단순만곡형, V-만곡형 그리고 슬롯만곡형 전개판의 3종에 와발생기를 부착하지 않은 경우와 부착한 경우에 대하여 성능 및 유체역학적 특성을 성능실험과 가시화실험을 통하여 비교해 보았다. 실험결과를 요약하면 다음과 같다. \circled1 단순만곡형전개판에 와발생기를 부착한 경우 최대전개력계수는 10~15% 증가, 항력계수는 2%미만증가, 양항비는 5~20% 증가하였다. \circled2 V-만곡형전개판에 와발생기를 부착한 경우 양항비가 10~20% 증가하였다. \circled3 슬롯만곡형에 와발생기를 부착한 경우 영각 20$^{\circ}$ 이내에서 최대전개력계수는 약 20%이상 증가, 항력계수는 5~20% 증가, 양항비는 약간 높게 나타났으나, 영각 25$^{\circ}$이상에서는 이들 계수의 값들이 기준형에 비하여 낮게 나타났다. \circled4 와발생기를 부착한 전개판에서 박리점이 기준형에 비하여 다소 후연에 나타났다. \circled5 와발생기에 따른 전.후면의 유속차는 단순만곡형의 경우 모든 영각에서 약 10% 증가, V-만곡형의 경우 전반적으로 증가하였으나 영각 25$^{\circ}$에서는 비슷하게, 슬롯만곡형의 경우 영각 25$^{\circ}$까지는 증가하는 것으로 나타났다. \circled6 와발생기에 따른 박리역의 크기는 단순만곡형에서 약 5~15% 감소, V-만곡형과 슬롯만곡형은 영각 15$^{\circ}$~20$^{\circ}$에서는 약 10% 감소, 영각 25$^{\circ}$ 이상일 때는 비슷하게 나타났다.

• 한국임상수의학회지
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• 제26권4호
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• pp.395-399
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• 2009

한국 수달의 복강 내에 무선추적 전파발신기를 수술적으로 이식하였으며 수술 후 입원해 있는 기간 동안 수달의 술 후 행동을 관찰하였다. 복강 내로 전파발신기를 삽입하기 위해 옆구리 오목 부위를 절개하여 접근하였다. 복강 수술 후 입원해 있는 기간 동안 13가지의 행동이 관찰 되었으며 입원기간 동안 각 행동이 보여지는 비율과 각 행동이 가장 빈번히 관찰되는 시간을 측정하였다. 본 연구는 수달에서 복강 내 이식물을 삽입하기 위한 수술적 기술을 제공하고 입원해 있는 동안의 수달 행동에 관한 기초적 정보를 제공할 수 있을 것이다.

• 한국환경생태학회:학술대회논문집
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• 한국환경생태학회 2004년도 학술대회지
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• pp.3-12
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• 2004

• 수산해양기술연구
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• 제53권4호
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• pp.337-348
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• 2017

The tension of warp from trawler and sea-floor contact can generate tilt and wake turbulence around otter boards. Preliminary measurements of otter board tilt and 3-D flow velocity during bottom trawl operations were taken using a vector instrument to investigate the effects of wake turbulence at the trailing edge of the otter board. Tilt data (i.e., yaw, pitch, and roll) at 1 Hz and flow data (velocities in the towing, lateral, and vertical directions) at 16 Hz were analyzed to determine their periods and amplitudes using global wavelet and peak event analyses. The mean period (${\pm}standard$ deviation) of the tilt from the peak event analysis ($5{\pm}2s$) was longer or double than that of flow velocity ($3{\pm}2s$). The two periods also had a significant linear relationship. The turbulence rate of flow was 30-50% at the trailing edge and was closely related to roll deviation. The frequency of phase difference ratios (i.e., peak time differences between tilts and flow periods) was significantly different from random occurrence in two trials, possibly due to side tidal effects. However, in the other trials, flow peaks were random, as shown by the even peak times between tilts and flows. Future studies should focus on reducing tilt variation, wake turbulence, and bottom contact to stabilize otter board motion.

• 수산해양기술연구
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• 제27권4호
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• pp.278-285
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• 1991

현재 사용되고 있는 전개판의 성능을 보다 향상시키기 위한 방안으로 비행기의 익이론에 기초를 두고, 전개판의 경계층을 흡입하거나 제거하는 방법 중에서 역류역을 흡입하는 슬롯(slot)을 전개판에 적용하였다. 성능분석을 위해서 단순만곡형전개판에 슬롯이 없는 기준형과 슬롯의 위치에 따른 5종의 모형전개판에 대하여 성능실험과 가시화실험을 통하여 그 성능과 유체역학적 특성을 비교해 보았다. 실험결과를 요약하면 다음과 같다. \circled1 최대전개력계수는 0.6C, 0.4C, 기준형, 0.8C, 0.2C의 순으로, 슬롯의 위치 0.6C인 전개판이 영각 27$^{\circ}$에서 1.59로 가장 우수하였다. \circled2 항력계수는 슬롯의 위치가 후연으로 갈수록 감소하며, 슬롯을 준 경우가 기준형보다 작게 나타났다. \circled3 양항비는 0.6C, 0.4C, 0.8C, 0.2C, 기준형의 순으로 모두 기준형보다 높게 나타났다. \circled4 0.2C, 0.4C 및 0.6C의 전개판이 기준형과 0.8C의 전개판보다 박리가 후연에서 발생하였다. \circled5 전개판의 전.후면에서 유속차는 영각 15$^{\circ}$~25$^{\circ}$까지는 점차 증가하고, 30$^{\circ}$에서는 감소하는 것으로 나타났다. \circled6 박리역의 크기는 0.6C의 전개판에서 가장 적게 나타났다.

• Animal cells and systems
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• 제8권3호
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• pp.231-233
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• 2004

Sequences of cytochrome b gene and control region of mitochondrial DNA from Korean common otters (Lutra lutra lutra L.) were examined to provide the genetic information for the conservation of this subspecies. Two haplotypes and one haplotype were revealed in cytochrome b gene and control region, respectively. The available sequences of European common otter (L. l. lutra) from GenBank were compared together with those of Korean common otter in order to determine the degree of sequence variation between them. In cytochrome b gene sequences, two haplotypes from Korea and two haplotypes of Europe showed differences in 12 of 1,045 sites. The Tamura-Nei nucleotide distances between two European haplotypes was 0.10% and those between two Korean haplotypes was also 0.10%, but those between Korean haplotypes and European ones ranged from 0.96% to 1.16%. In the control region, one Korean haplotype and seven European ones showed differences in seven of 300 sites; the Tamura-Nei distances among seven European haplotypes were 0.34% to 1.01%, but those between Korean haplotype and European ones ranged from 1.01% to 1.69%. Although further molecular and morphological studies with specimens from eastern Asia including Amur region and northeast China are needed, it is possible that the Korean common otter might be closer or identical to the far-eastern Asian common otter, L. l. amurensis Dybowski.