• 수산해양기술연구
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• 제50권3호
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• pp.274-283
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• 2014

Swelling of the heat-treated netting for gillnet was estimated through the netting height in square acrylic tank. Experimental Nylon netting and PBSAT netting were heat-treated by using the high-degree vacuum method in hot water after net making. Heat-treatment temperatures were conducted with Nylon netting $105^{\circ}C$ and PBSAT netting $62^{\circ}C$, $65^{\circ}C$, $66^{\circ}C$, $67^{\circ}C$. The swelling measurement method of a netting using the square tank was capable of the reduction measurement errors comparing with measurement methods of a mesh inner angle and the shortening rate of a mesh size. In addition, this method was available to comparison evaluation for each netting more easily. Wet type heat-treatment apparatus with high-degree vacuum was shown higher $7{\sim}8^{\circ}C$ inner side temperature than a setting temperature. The tensile strength and elongation of Nylon netting and PBSAT netting were shown higher wet condition than dry condition. The tensile strengths of PBSAT monofilaments in dry and wet condition were sharply decreased at heat-treatment temp. $75^{\circ}C$ than heat-treatment temp. $74^{\circ}C$.

• Fisheries and Aquatic Sciences
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• 제14권2호
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• pp.130-137
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• 2011

Visual stimuli of nets, which affect fishing selectivity, vary by twine diameter, color, and material under different light conditions and visual geometries. In this study, two cylindrical model codends of two mesh sizes, 28 and 43 mm, were made of high-contrast, dark brown polyethylene (PE) netting twine and low contrast, light-blue polyamid (PA) monofilament twine. Each model codend was filled with juvenile seabream and set in the water channel of a light-blue circular tank under a flow speed 0.8 m/s for 30 min. Light conditions were set to relatively bright, dim, and dark. The resulting retention rates of juvenile seabream were 15-35% lower for the low-contrast codend with PA monofilament than for the high contrast PE twine netting under bright and dim light conditions, while no difference was observed under dark conditions. The effects of mesh size and netting contrast on the retention rate were dependent on the light level, while the retention rate due to netting contrast was independent of mesh size. Therefore, low-contrast nets in the codend could help to reduce juvenile bycatch by disturbing the orderly optomotor response.

• 수산해양기술연구
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• 제6권1호
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• pp.14-22
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• 1970

국내에서 생산하고 있는 Nylon 6 망사의 원사는 대부분 일본에서 수입하여 제망해서 수출하고 있다. 그러나 우리가 수입하고 있는 원사중 어느 회사의 원사가 우수한지 또한 염색 가공후의 망사의 성질변화에 대하여서는 그다지 알려져 있지 않으며 그뿐만 아니라 같은 Nylon 6 망사라 할지라도 제조 공정에 따라 망사의 성질이 달라질 수 있으므로 저자들은 일산 Nylon6 망사를 가지고 염색전과 후의 강신도와 염색후의 수축등을 시험 비교해 보았다. 특히 망사는 수중에서 사용되기 때문에 습윤시의 인장 강도와 신장이 겁습에 비해 어떻게 변화하는가를 관찰하였다.

• Current Research on Agriculture and Life Sciences
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• 제14권
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• pp.61-65
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• 1996

네트멜론에 있어서, 주당(株當) 엽수(葉數)를 22매(枚)로 제한하여 8, 10, 12, 14절의 1과착과와 8-9, 10-11, 12-13, 14-15절의 2과 착과구를 설치하고 각각 네트 발현(發現), 품질(品質) 및 수량(收量)에 미치는 영향(影響)이 어떠한지 알고자 '슈퍼VIP' 멜론을 이용하여 비닐하우스 내에서 춘작재배(春作栽培)로 시험하여 다음과 같은 결과(結果)를 얻었다. 1) 주당(株當) 1과(果) 착과(着果)는 착과절위(着果節位)에 관계없이 네트발현이 양호하였으며, 착과절위(着果節位)가 높을수록 과중(果重), 과장(果長), 과경(果徑), 과육(果肉)두께가 증가되었고, 당도(糖度)와 저장성(貯藏性)은 떨어졌다. 2) 주당(株當) 2과(果) 착과(着果)는 착과절위(着果節位)가 높을수록 네트 발현(發現)이 우수하였고, 당도(糖度), 과중(果重), 과장(果長), 과경(果徑), 과육(果肉)두께가 증가하였으나, 저장성(貯藏性)은 차이(差異)를 보이지 않았다. 3) 네트발현, 당도 저장성등 상품성(商品性)은 주당(株當) 1과(果) 착과(着果)가 2과(果) 착과(着果) 보다 뛰어났으며, 12절(節)에서 1과(果) 착과(着果)한 것이 가장 우수했다. 4) 수량성(收量性)은 주당(株當) 2과(果) 착과(着果)가 1과(果) 착과(着果)보다 증가(增加)하였다.

• 수산해양기술연구
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• 제21권2호
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• pp.89-98
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• 1985

As a primary step in studying the effects of the netting porosity on the net-shape in the four-seam trawling net, a series of experiments were performed changing the porosity of each panel, with the simplified mo:iel of the bag net made of porous vinyl film and that ma:ie of net webbing. These models were suspended horizontally in circularly flowing water, with two pairs of susp~nding threais to four points of symetry at the border of the bag mouth in place of both wing nets. And then, the section shape of the bag mouth photographed and the tensions on both pairs of suspending threads were measured with two load cells in circularly flowing water. From the results, the auther estimated an experimental equation from the relationship between the porosity of each panel in the bag net and the section shape of the bag mouth, h/w=k (l-Pr_u/lPr_s)

• Ocean Systems Engineering
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• 제7권2호
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• pp.143-155
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• 2017

For complex flexible structures such as nets, the determination of drag forces and its deformation is a challenging task. The accurate prediction of loads on cages is one of the key steps in designing fish farm facilities. The basic physics with a simple cage, can be addressed by the use of experimental studies. However, to design more complex cage system for various environmental conditions, a reliable numerical simulation tool is essential. In this work, the current load on a cage is calculated using a Morison-force model applied at instantaneous positions of equivalent-net modeling. Variations of solidity ratio ($S_n$) of the net and current speed are considered. An equivalent array of cylinders is built to represent the physical netting. Based on the systematic comparisons between the published experimental data for Raschel nets and the current numerical simulations, carried out using the commercial software OrcaFlex, a new formulation for $C_d$ values, used in the equivalent-net model, is presented. The similar approach can also be applied to other netting materials following the same procedure. In case of high solidity ratio and current speed, the hybrid model defines $C_d$ as a function of Re (Reynolds number) and $S_n$ to better represent the corresponding weak diffraction effects. Otherwise, the conventional $C_d$ values depending only on Re can be used with including shielding effects for downstream elements. This new methodology significantly improves the agreement between numerical and experimental data.

• Fisheries and Aquatic Sciences
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• 제14권1호
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• pp.62-69
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• 2011

The effects of actively stimulating devices (ASD) on juvenile flatfish escape were studied to increase escape rates from the cod end by encouraging fish to approach the net wall. Two kinds of ASD were designed: a fluttering net panel, i.e., a free-end flag-like net panel, and a double conical rope array. Escape responses of juvenile bastard halibut were observed in a circulating water channel using two model cod ends, one made with diamond-shaped 43-mm-mesh-size polyethylene (PE) as a high-contrast cod end and the other with polyamid (PA) mono-ply as a low-contrast cod end. Retention rate was significantly lower with the double conical rope-array ASD in the PE cod end than with conventional PE cod ends only or the fluttering net-panel ASD inside the PE cod end. Mean retention rate with the low-contrast PA cod end was also significantly lower than that with the high-contrast PE conventional cod end. Therefore, active fluttering devices using a double conical rope array together with less visible low-contrast netting in the cod end could help to reduce the bycatch of juvenile flatfish by weakening their optomotor response and actively driving fish to the side net panel.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.153-162
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• 2005

The structural specification of the rockfall prevention fence installed on the road section is computed according to the hypothetic rockfall energy, and the absorbable energy of the rockfall prevention fence is defined as the sum of the absorption energies of the wire rope, one of the components, the steel support and the wire netting. But the results of the field tests confirmed that the absorption energy of the rockfall prevention fence is not the sum of the energies sustainable by the components, but it is affected by the absorbable energy of part of the components. This shows there are problems with the method of computing the absorption energy of the rockfall prevention fence of the road. So in this paper, as a way of solving the problems, the effects of improving the performance through positional changes of the existing components and the effects of improving the performance through structural changes by expanded metal are checked through tests, and a plan was proposed to solve the problems with the standards of installing the conventional rockfall prevention fence.

• 한국지반환경공학회 논문집
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• 제15권12호
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• pp.53-59
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• 2014

본 논문에서는 경험에 따라 비합리적으로 설계되고 있는 낙석방지망의 합리적인 설계를 위한 기초자료를 획득하기 위해 표준 단면을 결정하고 비탈면의 경사, 높이, 낙석의 무게, 이격거리 등의 매개변수가 도약높이나 운동에너지, 통과속도 등 낙석의 거동에 미치는 영향을 분석하였다. 낙석의 무게는 400, 700, 1,000 kg으로 변화하고 20 m 높이를 기준으로 낙석방호시설이 낙석의 거동에 영향을 미칠 수 있는 1:0.5($63^{\circ}$), 1:0.7($55^{\circ}$)의 경사에 대해 수행하였으며, 낙석의 낙하높이를 3, 15, 20 m를 변경시켜가면서 해석을 실시하여 사면 하부에 발생하는 최대운동에너지의 변화를 분석 평가하였다. 해석결과, 낙석방지망의 설계 시 현행과 같이 일률적인 적용에서 벗어나 사면의 경사와 예상되는 낙석의 규모나 무게, 법면의 상황 및 낙석의 모양, 낙석 운동형태 등 다양한 조건을 고려한 설계가 필요할 것으로 판단된다.

• 기술혁신학회지
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• 제12권3호
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• pp.582-613
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• 2009

본 연구의 실증분석은 다양한 금융규제가 기술혁신에 미치는 영향에 대하여 분석하였다. 은행 건전성 규제의 경우, 금융시장의 안정성 확보를 위한 건전성 규제(바젤 II)는 R&D 수행기업 간 양극화 현상을 가져올 수 있다. 유의할 사항은 일반적으로 자본금 규제가 신용등급이 낮은 중소기업 그룹에게 부정적 효과를 가져온다고 인식되고(손소영 2006), 우리의 연구도 이것을 뒷받침하고 있다. 하지만 실증분석 결과는 기술혁신 기업이라 하더라도 신용등급이 우수한 경우에는 바젤 II가 오히려 기회(opportunity)를 제공할 수 있으며 따라서 혁신자금 조달이 더 용이해질 수도 있다는 점을 보여준다. 다음으로, 금리규제는 금리 변동성이 기술혁신에 부정적인 영향을 미쳤던 것으로 나타났다. 또한 최근 진행되고 있는 금융기관 간 업무영역 규제의 완화와 이에 따른 업종간 겸업화 강화 경향이 R&D 투자에 긍정적인 영향을 미칠 가능성이 있음을 확인하였다.