• Title, Summary, Keyword: Sinking speed

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A study of the sinking speed of longlines influenced by bait properties and anchor weights (연승의 침강속도에 영향을 미치는 미끼의 특성과 앵커 무게에 관한 연구)

  • Lee, Ji-Hoon;Lee, Chun-Woo;Karlsen, Ludvig
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.46 no.3
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    • pp.214-222
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    • 2010
  • The paper presents investigations on to which degree the sinking speed of longlines is influenced by type of bait, bait sinking orientations and anchor weights. The main aim of this study is to obtain further insight in the ocean current displacement phenomena in demersal longlining. The sinking speed is one of the main factors deciding the current displacement. In an ongoing project, sinking speed experiments with longlines with 6 kg and 10 kg anchor weights have been carried out in the Trondheim fjord. The longlines used in the first experiments were rigged without bait and hook. The results of these experiments with two different anchor weights have revealed only a slight difference in the sinking speed, except for the part near to the anchors, even though the sinking speed of longlines in general is supposed to be much influenced by the anchor weights. The reason for the obtained result is supposed to be that the experiments have been carried out at relative shallow waters. Further studies have included bait sinking experiments in the flume tank. The experiments showed that the drag coefficient of "fillet type (flat)" bait varied from 0.763 to 1.735, while it for "elliptic type" bait varied from 0.62 to 1.483. Other activities have included calculation of the sinking speed of longlines as a function of the established resistance coefficients of bait of various shape and size for commercial longlining. The calculated sinking speed of a longline with the fillet type bait was found to be 12.4 to 16.5% lower than for a longline without bait.

Dynamic analysis and improvement of the sinking performance of the Vietnamese tuna purse seine using numerical methods

  • HUNG, Dinh Xuan;LEE, Chun Woo;PARK, Subong
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.52 no.1
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    • pp.1-8
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    • 2016
  • In this study, numerical method was used to assess technical properties and improve the Vietnamese tuna purse seine. The data were extracted from the two national level projects. The study results showed that average lead-line sinking speed reached 0.139 m/s and 0.143 m/s and maximum sinking depth was 61.6 m and 65.8 m for The gears 2003 and 2014 respectively. The maximum tension on ring line of The gear 2003 was 4,742 kgf and 2014 was 4,219 kgf. The improved tuna purse seines I, III and IV showed similar sinking speed results with 0.220 m/s, 0.219 m/s and 0.219 m/s respectively. The average lead-line sinking speed of the improved gear II was lowest with 0.215 m/s. The maximum lead-line sinking depth of the four improved gears I, II, III and IV were 116 m, 112 m, 115 m and 114.9 m respectively. Maximum tension on ring line of the improved gears I, II, III and IV were 5,657 kgf, 5,406 kgf, 5,645 kgf and 5,654 kgf respectively. The improved tuna purse seine IV is the most suitable for Vietnamese tuna purse seine fishery, Which corresponds with tuna purse seiner scale and its fishing supporting equipment at the present.

Calculating and Measuring the Sinking Performance of Small-scale Purse Seine Gear in Java, Indonesia, to Improve the Gear

  • Widagdo, Aris;Lee, Chun-Woo;Lee, Jihoon
    • Fisheries and aquatic sciences
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    • v.18 no.2
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    • pp.221-227
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    • 2015
  • We analyzed the small-scale purse-seine gear that is used along the North Coast of Java, Indonesia, using computer-aided tools to modify the gear. Data from the middle position of the leadline showed that the maximum depth reached by the net was 30 m. A similar result was also calculated. According to the calculated result, the mean sinking speed of the current gear at the middle position of the leadline was 0.13 m/s, and the maximum tension during pursing was 1,794 kgf. The best sinking performance was found in modified gear that used a 30.3 mm mesh knotless polyester net. The maximum depth reached by the net was 38 m, and mean sinking speed was 0.16 m/s at the middle position of the leadline. The maximum tension during pursing was 1,044 kgf. Independent sample t-test results show that the mean sinking depth and sinking speed in the simulated and measured results did not differ (P > 0.05). These results are expected to improve the efficiency and selectivity of small-scale purse seine gear.

Studies on the improvement of the productivity of purse seine fishery-II - The sinking movements with the flow velocity on the model purse seine of the subjective power block and triplex (선망어업의 생산성 향상에 관한 연구-II - 파워불록과 트리플랙스용 선망 모형의 유속에 따른 침강거동 -)

  • Kim, Suk-Jong
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.43 no.1
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    • pp.1-11
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    • 2007
  • It is the basic studies for productivity improvement and laborsaving of purse seine fishery. Because the seine shape is apt to be transformed in seine shooting process due to the effect of tide, this study is intended to establish 4 steps, whose flow velocity are 0, 2, 4 and 6cm/sec, in flume tank and perform the experiment to review the character. We used two model seines designed on the scale of 1 to 180 based on the power block seine, which is the mackerel purse seine generally used in the near sea of Jeju Island and triplex seine, which is the mackerel purse seine of one boat system fishing expected in the future, for the experiment, analyzed of the sinking movements on the two seines and its results are as follows. In the setting over the flow velocity 6cm/sec, experiment was impossible because of flying and transformation of seine were severe. The sinking movements of P seine and T seine generally showed linear phenomenon and the sinking speed showed gentle curve shape. Sinking tendency was distinguished by existence of flow velocity. When there is flow velocity, it showed the phenomenon that it sinking by similar type. Although sinking depth and sinking speed did not show distinguished classification, P seine shows bigger than T seine. When there was in flow velocity, the elapsed time(Et) and sinking depth (PDp, TDp) of P seine and T seine can be shown such experimental equations as PDp=(0.21V+4.96)Et-(0.62V-0.10) and TDp=(0.19V+4.95)Et-(0.72V+0.34). When there was in flow velocity, the elapsed time and siking speed (PSp, TSp) of P seine and T seine can be shown such experimental equations as $PSp=-0.11Et^2+1.42Et+1.75\;and\;TSp=-0.11Et^2+1.41Et+1.37$.

Sinking depth of tuna longlines related to mainline materials in the North Pacific Ocean (북태평양 중부공해에서 조업하는 다랑어연승어구의 모릿줄 재질에 따른 침강수심)

  • Jo, Hyun-Su;Hwang, Seon-Jae;Lee, Ji-Hoon;An, Doo-Hae;Moon, Dae-Yeon
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.47 no.3
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    • pp.173-182
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    • 2011
  • The purpose of this paper is to provide useful information for fishermen in the manner of investigation a sinking speed of current type tuna longline gear at the North Pacific Ocean as a new developed tuna longline fishing ground. The sinking depth of mainline in connection with different basket was investigated. The experiments were also performed with different materials such as Supermansen (i.e., PE) and Hitech (i.e., PA) for the mainline to investigate the sinking depth of mainline and hooks. Furthermore, the relation between the sinking depth of hooks and catches are investigated also. The sinking depth of mainline at the first and the last shooting basket shows deeper than that of middle part of a basket due to reduced shortening ratio. The sinking depth of mainline and hook with Hitech material shows more shallow than that of Supermanse material, even the Hitech case was designed to sink deeper than that of Supermanse case. The highest catches arise at the middle part basket as the hook number 7 with around 248m sinking depth. From the results, longline with Hitech material is needed to increase the sinking force for reaching the relevant sinking depth. Moreover, the current strength at the North Pacific Ocean will be considered for further commercial fishing.

A Study on the Purse Seine Comparison of Sinking Speed and Tension of Purse Line in Two Nets , Made of Knotted Webbing and Raschel Webbing (건착망의 연구 - 사절망과 라셀망의 심항력과 장력의 비교 -)

  • Bag, Jeong-Sig
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.16 no.2
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    • pp.55-59
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    • 1980
  • The authors carried out a model experiment to compare the sinking speed and the tension of the purse line in two nets, made of knotted webbing (Model A) and Raschel webbing (Model B). The model net was made in 1/450 scale of the actual net being commercially used in the Korean coastal waters for mackerel. The headline of the model net is 200cm and the maximum height 50cm. The weight of the sinker in water was changed 4g and its multiplication till 20g. The results obtained are as follows: 1. Sinking speed of the model A was faster 1. 4 to 1. 8 times than that of model B. 2. Tension of the purse line of the model A was 10 to 20 percent less than that of model B.

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Passenger evacuation simulation considering the heeling angle change during sinking

  • Kim, Hyuncheol;Roh, Myung-Il;Han, Soonhung
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.11 no.1
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    • pp.329-343
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    • 2019
  • In order to simulate the evacuation simulation of a ship during a sinking, the slope angle change of the ship must be reflected during the simulation. In this study, the passenger evacuation simulation is implemented by continuously applying the heeling angle change during sinking. To reflect crowd behavior, the human density and the congestion algorithm were developed in this research and the walking speed experiment in the special situation occurring in the inclined ship was conducted. Evacuation simulation was carried out by applying the experimental results and the change of the walking speed according to the heeling angle of the ship. In order to verify the evacuation simulation, test items suggested by International Maritime Organization (IMO) and SAFEGUARD Validation Data Set conducted on a large Ro-PAX ferry (SGVDS 1) which performed real evacuation trial in full-scale ships were performed and the results of simulation were analyzed. Based on hypothetical scenario of when a normal evacuation command is delivered to the passengers of MV SEWOL in time, we predicted and analyzed the evacuation process and the number of casualties.

The behavior characteristics according to the quality of the sinkers of the yellow croaker drift gill net in the field (발돌재질에 따른 참조기유자망의 수중거동특성)

  • Kang, Kyoung-Bum;Kim, Suk-Jong
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.46 no.1
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    • pp.10-19
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    • 2010
  • As a series of studies about improvement of yellow croaker drift gill net fishing gear and development of the labor saving fishing system, this study analyzed the behavior characteristics of fishing gear, which does use three types of different sinker materials in the field tests. The result of maritime performance test indicated that the fishing gear which used the lead reached the maximum depth and bio ceramics hauled to the surface of water the fastest. The correlation between the sinking time (St) and depth (Dsl, Dsc, Dsb) of maritime performance test can be shown such experimental equations as Dsl=2.70St - 0.75, Dsc = 2.38St - 1.15, Dsb = 1.77St - 4.00. The correlation between the hauling time (Ht) and depth (Dhl, Dhc, Dhb) of maritime performance test can be shown such experimental equations as and Dhl = 7.88Ht + 35.48, Dhc = 7.80Ht + 40.01, Dhb = 7.95Ht + 36.44.

Abutment Sinking and Fitness of Conical Internal Connection Implant System according to Loading Condition (하중조건에 따른 원추형 내측연결 임플랜트 시스템에서 지대주 침하 및 적합에 관한 연구)

  • Lee, Hal-La;Kim, Hee-Jung;Son, Mee-Kyoung;Chung, Chae-Heon
    • Journal of Dental Rehabilitation and Applied Science
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    • v.24 no.1
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    • pp.77-89
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    • 2008
  • The purpose of this study was to evaluate internal conical abutment sinking and fitness according to the loading condition. In this study, Alloden implant fixture and two abutment(conventional, FDI) systems were used. Each abutment was applied 1 time of finger force, 3 times of malleting force, 5 times of 20kg and extra several times to the fixture until the amount of abutment singking showed no change. Then, the length of abutment to fixture which was binding lightly with no pressure state was measured by Vernier caliper. After loading application, the length was remeasured and the amount of sinking was calculated. The implant was buried in unsaturated polyester (Epovia, Cray Valley Inc. Korea) for making a comparison between the change of length and fitness of abutment-fixture connection part. Then All samples were cross-sectioned with high speed precision cut-off(accutom-5, Struers, Denmark). Finally, The result were observed and analyzed using FE-SEM (field emission scanning electron microscopy).

The Sinkage Speed by Ship's under Water Damage (선저파공이 침수속도에 미치는 영향)

  • 박석주;이동섭;박성현
    • Journal of the Korean Institute of Navigation
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    • v.25 no.4
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    • pp.417-422
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    • 2001
  • Every ship might be exposed to collision, grounding and/or various accidents. They may make some underwater holes on the hull. An underwater damage would cause her loss of buoyancy, trim, and inclination. Although a ship has some provisions against these accidents, if the circumstance is serious, she would be sunk or upsetted. Because of varieties of type of accidents, one could not prepare all of them. Many subdivision could prevent them, but it is difficult to realize it due to rising costs. This paper deals with physical phenomena of sinkage and an application on box type ship, and some results are earned as follows; 1. sinkage speed up to the level of the damage hole is increased proportionally, and is decreased proportionally after filling the level. 2. the curve of draft shows cup type of second order polynomial up to the damage hole level, and shows cap type of second order polynomial after filling the level. 3. if damage occurs beneath half of the draft, changes of head and displacement, and sinking speed follow almost straight lines. 4. by careful observation, sinkage speed could be predicted.

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