Seong-Wook Park

Development and physical properties on the monofilament for gill nets and traps using biodegradable aliphatic polybutylene succinate resin

This study was aimed not only to develop the gill net and trap made of biodegradable monofilaments in order to prevent a ghost fishing and to protect marine ecosystem, but also to analyze their spinning process and physical properties. Results showed that the spinning speed of biodegradable polybutylene succinate(PBS) monofilament was estimated to be approximately 100m/min when spinning temperature and cooling water temperature were adjusted at and , respectively. The breaking loads of PBS monofilaments were estimated to be at , at , and at in the dry condition, respectively. However, its breaking loads in the wet condition were reduced by 2.4-5.5%, compared to those in the dry condition. The knotted strength of PBS monofilament at was estimated to be 98.6% of PE in the dry condition. The breaking load of PBS monofilament at was evaluated to be 81.8% of PA, and its softness showed 3 times less than that of PA in the wet condition. The breaking load of PBS monofilament at was 95.3% of PA, and its softness showed 1.6 times less than that of PA in the wet state. However, the load elastic elongations of two kinds of monofilaments were estimated to be 1% higher than that of PA.

Weatherability of biodegradable polybutylene succinate(PBS) monofilaments

Biodegradable polybutylene succinate(PBS) is an environment friendly plastics for fisheries, because it can mitigate the ghost fishing problem caused by gill-net and trap fisheries. To evaluate photodegradability of PBS monofilament in comparison with polyamide(PA) and polyethylene(PE) monofilament, these 3 types of monofilaments were spun and exposed to ultraviolet light(UV) of weather-ometer for 900 hours, and then their modification, crystal structure, strength, and extensibility were analysed. PBS monofilament did not show any crack and maintained its crystal structure after 900 hour exposure to UV whereas PE monofilament began showing cracks and structure modification after 600 hour exposure. Under UV exposure, the strength and extensibility decreased more rapidly in PBS than in PA and PE. We estimate that gill nets made of PBS monofilament can endure for about 1 year. The breaking strength and elongation decreased linearly with the exposure time for the 3 types of monofilaments. The derived regression equations of the residual tenacity(RT, kg/) and the residual extensibility(RE, %) with the exposure time in year(Y) for each monofilament were; PBS : RT

Preparation and physical properties of biodegradable polybutylene succinate/polybutylene adipate-co-terephthalate blend monofilament by melt spinning

In order to improve the breaking strength and elongation of Polybutylene succinate (PBS) monofilament, themonofilament was produced by blending PBS and Polybutlyne adipate-co-terephthalate (PBAT). ThePBS/PBAT blend monofilament was prepared by the melt spinning system, and the weight ratios of thecompositions of PBS/PBAT was 100/0, 95/5, 90/10 and 85/15, respectively. The breaking strength,elongation, softness and crystallization of PBS/PBAT blend monofilament were analyzed by using atensionmeter, softness measurement, X-ray diffractometer in the both dry and wet conditions. ThePBS/PBAT blend monofilaments were spun in the take-up velocity of 1.19m/sec under the drawing ratio of6.8:1 condition. The production volumes of PBS/PBAT blend monofilaments showed 20% less than that ofNylon. The breaking strength of PBS/PBAT blend monofilaments were decreased as PBAT contentsincreased, while elongation and softness were increased. In case of PBAT content were over 5%, thebreaking strength, elongation and softness of PBS/PBAT blend monofilaments were not shown to increasein spite of increasing in PBAT contents. Based on these results, it was possible to make the monofilamentswith the maximized physical properties when the PBAT contents at 5%.Keywords: Biodegradation, Polybutylene succinate, Monofilament, Physical properties

Fishing power estimation of biodegradable traps in the East Sea

For an effective management of fisheries resources, it is very important that to make clean inhabitation environment and to preserve fisheries resources. The material which is mainly used as fishing gear in modern times, is polyethylene, polypropylene, polyamide, etc., chemical fiber. And lost fishing gears which are make of these, occur ghost fishing and ocean pollution. To solve these problem, we development biodegradable fishing trap using the polybutylene succinate (PBS). Developed traps are for red snow crab (Chionoecetes japonicus) and shrimp, major traps in the East Sea, and we carried out fishing research using two kind traps in the coastal sea of Ayajin-port (Goseong) to analysis fishing efficiency of PE trap and PBS trap. As a result for fishing experiment (year 2005-2006) of red snow crab trap, two kind traps were almost the same in catches and length composition. During a experiment, parts of meshes, used for over 1 year, were cut by biodegradation. As a result for fishing experiment (year 2007) of shrimp trap, northern shrimp (Pandalus eous), coonstripe shrimp (Pandalus hypsinotus) and morotoge shrimp (Pandalopsis japonica) were catched, and the almost is northern shrimp. Two kind traps were almost the same in catches and length composition. In accordance with these result, it is recommended that the developed traps are have to commercialized because the fishing powers of PE traps and PBS traps were same. But biodegradation speed is have to controled in consideration of ocean microorganism volume and traps life.

Productive efficiency of the sandfish Arctoscopus japonicus coastal gillnet fishery using stochastic frontier analysis

It is important to estimate the productive efficiencies of industries, especially the fishing industry, in order to determine policies that can improve business conditions. In this study, the productive efficiency of the sandfish coastal gillnet fishery on the east coast of Korea has been estimated using stochastic frontier analysis (SFA). A translog production function wherein the inefficiency was represented by a truncated-normal distribution was established; the output variable was the trip production quantity, the input variables were physical production factors directly related to the fishing activities of vessels, such as tonnage, horsepower, and the number of employed fishers. The average productive efficiency of the sample was 0.59 [0.40–0.79], which implied that productive inefficiency occurs in sandfish coastal gillnet vessels. Moreover, it was verified that there are no differences among the average productive efficiencies of fishing vessels of different tonnages.

The estimation of the optimum mesh size selectivity of a drift net for yellow croaker (Larimichthys polyactis) using by the SELECT model

참조기는 우리나라에서 오래 전부터 고급으로취급하고 있는 대표적인 어종 중의 하나로 우리나라 남서해 연안과 동중국해 등의 해역에서주로 어획되고 있다 . 최근 참조기 자원량은 증감을반복하고 있으나 전반적으로 감소 추세에 있다. 이와 더불어 주요 어장인 동중국해에서는 어획노력량이 과다하게 투입되고 있고 중국 어선들과 경쟁조업 등으로 유자망어업의 경우 어장사고가 빈번히 발생하고 있다 . 특히 생태적인 측면에서는 자원 감소로 인하여 개체의 성장과 성숙이 매우 빨라짐에 따라 성숙개체의 체장이 소형화되고 있다 . 이러한 관점에서 우리나라에서는남서해안 참조기를 자원 회복 대상어종으로

Effects of heat setting temperature conditions on the mechanical properties of Polybutylene succinate (PBS) monofilament yarn after net-making

The monofilament with 0.304mm of diameter was produced using a polybutylene succinate (PBS) resin, and a gill net was made by it. We investigated the impact of heat setting temperature on the mechanical properties, knot state and height of gill net. Heat treatment was carried out using the high pressure steam machine for 20 minutes at temperature of , , and . Before heat treatment, the strength and elongation of PBS monofilament were estimated to be , 23.8% at unknot, , 18.8% at single knot, , 22.9% at double knot in dry condition, respectively. The strength and elongation of PBS monofilament with double knot were decreased as heat setting temperature increased, and the decreasing rate of strength was showed to be higher than that of elongation. It was not found any differences in strength and elongation of PBS monofilament yarn with double knot at the and of heat setting temperature by 5% significance of T-test, but there was a significant difference at the and of heat setting temperature. The net`s height and length from leg to leg appeared no differences at the and of heat setting temperature. In results, it was investigated that the PBS monofilament gill net with the maximized physical properties could be manufactured at of heat setting temperature using a high pressure steam machine for 20 minutes.

Acoustical backscattering strength characteristics and density estimates of Japanese common squid distributed in Yellow Sea

), which was distributed in East Sea, was recently caught in Yellow Sea during asummer season from 2006. The fishery resources density research was carried out in Korea-ChinaProvisional Water Zone using trawl fishing gear and acoustics in National Fisheries Research &Development Institute in Korea. This paper showed the analysis on the acoustical backscattering strength bytwo frequencies(38kHz, 120kHz) for Japanese common squid by acoustical scattering theoretical modelbased on size distribution for survey period, and estimate the density distribution for squids integrated layerwhich was extracted from any scatterers distributed in water column using two frequency difference methodwhich has been used to distinguish fish shoals or specific target scatterers from sound scattering layer whichis composed of various zooplankton. Furthermore, the entire range of their density estimation was suggestedusing by Monte Carlo simulation under considering each uncertainty such as size distributions or swimmingangle and so on in survey area.Key words : Japanese common squid, Todarodes pacificus, Acoustical scattering theoretical model, DWBA,Density estimates

The characteristics of the flow field around canvas kite using the CFD

This research aims at establishing the fundamental characteristics of the kite through the analysis of the flow field around various types of kites. The approach of this study were adopted for the analysis; visualization by CFD(computational fluid dynamics). Also, the lift/drag and PIV(particle image velocimetry) tests of kites had been performed in our previous finding. For this situation, models of canvas kite were designed by solidworks(design program) for the CFD test using the same conditions as in the lift/drag tests. And we utilized FloWorks as a CFD analysis program. The results obtained from the above approach are summarized as follows: According to comparison of the measured and analyzed results from mechanical tests, PIV and CFD test, the results of all test were similar. The numerical results of lift-coefficient and drag-coefficient were 5-20% less than those of the tests when attack angle is . In particular, it showed the 20% discrepancy at . The numerical results of the ratio of drag and lift were 8-13% less than those of the tests at and 10% less than those of the tests at . Pressure distribution gradually became stable at . In particular, the rectangular and triangular types had the centre of the high pressure field towards the leading edge and the inverted triangular type had it towards the trailing edge. The increase of the attack angle resulted in the eddy in order of the rectangular, triangular and inverted triangular type. The magnitude of the eddy followed the same order. The effect of edge-eddy was biggest in the triangular type followed by the rectangular and then the inverted triangular type. The action point of dynamic pressure as a function of the attack angle was close to the rear area of the model with the small attack angle, and with large attack angle, the action point was close to the front part of the model.

Entering behavior and fishing efficiency of common octopus, Octopus minor to cylindric trap

The behavior patterns of common octopus, Octopus minor to a cylindric trap were examined in the water tank using a video camera in order to know entering mechanism to the trap and to improve it. Fishing efficiency by 2 kinds of traps(A: 3 entrances, B: 2 entrances) was investigated in the coastal area of Deugryang Bay from May to July, 2005. Common octopus tends to approach by swimming more than walking towards trap. When they approached to the trap, they showed much more behaviors that sate at the around than upper part of it. Approaching behaviors of common octopus was more vigorous at nighttime than daytime on the trap, they showed the most vigorous action between 2 am and 4 am of the day. The rate of staying 30 seconds over around the trap was 41.5% in the nighttime. CPUE(g/trap) of common octopus caught by A type trap was 21.4% higher than the B type trap but there was no difference on the significance level of 5% by the ANOVA. Catch rate of common octopus and by-catch species caught by the A type trap were 97.2%, three and 98.7%, two for B type trap, respectively.