• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.4
• /
• pp.432-438
• /
• 2017

The primary objective of the current work was to develop a standardized retrofit hull form capable of saving energy based on existing vessels. The bow shape of existing vessels was investigated, giving consideration to design draft and speed. Resistance performances were assessed for existing vessels according to operating conditions. Commercial CFD codes and model test materials were used for assessment of effective power. Three retrofit hull forms with minimum resistance were selected given real operating conditions. These vessels were named after customized ready-made hull forms to enable ship owners to make easier choices. The effective power of each vessel was estimated under real operating conditions. Subjects were operated with the lowest draft, and performance for retrofit No. 3 showed an 11-16% improvement in effective power at low speed ranges of 16-18 knots compared to existing vessels. When operated with a middle draft, performance for retrofit No. 3 showed a 6-11% improvement in effective power at low speed ranges compared to existing vessels. When operated with the highest draft, performance for all vessels showed little difference in effective power.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2003.05a
• /
• pp.215-220
• /
• 2003

최근 우리나라 연안어업은 한 일, 한 중어업협정, WTO 가입 등으로 주변 환경이 급격하게 변화되는 한편, 연근해 어자원의 감소와 근해어업과의 경쟁조업 등으로 인해 경영수지가 극도로 악화되고 있다. 이에 따라 정부에서는 연안어업의 경영수지 개선을 목적으로 1척의 선박으로 3개 이하의 업종을 허가하여 여기에 맞추어 선택조업이 가긍하도록 하였다. 하지만 기존선박은 단일업종을 대상으로 한 전용선반으로 건조되어 업종변경시 개조비용 발생은 물론 이거니와 개조에 따른 조업중단 또는 차질로 제 효과를 얻지 못하고 있는 실정이다. 그리고, 조선공학적 제 성능에 관한 면밀한 검토가 부족한 가운데 개조 사용함으로써 안정성을 저해하거나 조업효율이 오히려 떨어져 복수조업요건을 모두 수용할 수 있는 새로운 선형개발이 요구되고 있다. 이에 본 논문에서는 동해역 2톤급 다목적어선을 대상으로 하여 어선세력, 어민요구사항 및 어로시스템 분석 등을 통해 다목적어선 대상업종을 선정하고, 선정된 업종의 어로장비를 동시탑재 또는 부분 교체하여 조업할 수 있는 선형을 개발함으로써 연안 어민의 선박건조비 절감, 업종 교체에 따른 부대 경비경감과 안전도 저해요인 해소에 기여하고자 한다.

• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.88-90
• /
• 2008

본 논문은 이중여자 유도형(DFIG) 풍력발전 시스템에서 유효전력과 무효전력을 직접적으로 제어하기 위해 가변구조제어의 일종인 스위칭 이득기반의 선형궤환(LFSG)제어기법을 제시한다. 개조된 직접전력제어기법 (DPC)과 공간벡터변조방식(SVM)은 제안하는 제어기법을 실현하기 위해 이용된다. 개조된 직접전력제어원리를 이용해서 설계된 LFSG제어기법은 널리 사용되고 있는 자속기준제어기법(FOC)에 비해서 간단한 제어구조로 강인성과 빠른 응답특성을 보인다. 시뮬레이션결과는 제안하는 제어전략의 타당성과 강인성을 확인해준다.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.7
• /
• pp.965-971
• /
• 2017

The primary objective of this study was to assess the energy efficiency performance of an optimized hull form capable of saving energy based on existing vessels. The bow shape of existing vessels was investigated, giving consideration to design draft and speed. Resistance performances were also assessed for existing vessels according to operating conditions. Commercial CFD codes and model test materials were used to assess effective power. An optimized hull form with minimum resistance was selected given real operating conditions. The effective horsepower of existing and optimized vessels was estimated at three speeds. Resistance performance for an optimized vessel showed a 6 % improvement in effective horsepower at design speed (12 knots) compared to existing vessels. Quasi-propulsive efficiency employed experimental data, while energy efficiency performance was analyzed based on operating days, bunker fuel oil C cost, daily fuel oil consumption and specific fuel oil consumption. Energy efficiency performance for an optimized vessel showed a gain of 30 million won per year in reduced costs at design speed (12 knots) compared to existing vessels.

• Textile Coloration and Finishing
• /
• v.17 no.3 s.82
• /
• pp.43-48
• /
• 2005

시료는 POY사 104/192로 Draw-Winder(독일, Zinser)를 이용하여 기존의 태세사 제조장치의 부분적인 개조를 통하여 길이방향으로 강제적인 태세사가 형성되도록 하는 제조기술을 이용하여 Thin-thick yam(T&T사) 6종류를 제조하였으며 제조 조건에 따른 구조변화와 물성에 대하여 연구 검토한 결과 다음과 같다. 결정화도의 변화는 Draw-winder의 R2 roller 온도가 상온인 경우보다 $100^{\circ}C$인 경우가 높게 나타났으며 태세사의 세(thin)부분의 복굴절률은 연신비가 높고 Draw winder의 roller(R2)의 온도가 높을수록 복굴절 값은 선형적으로 증가하였다. T&T사 제조시 연신 온도가 상온인 경우는 Thin부분만 연신이 진행되고 Thick 부분은 원사인 POY사의 성질이 그대로 유지하고 있음을 알 수 있고 R2 roller 온도가 상온에서 제조된 시료의 초기탄성률은 약1.5-2.0kgf/denier 정도로 높게 나타났으나 $100^{\circ}C$로 제조된 시료는 약 0.2-0.8kgf/denier 정도로 낮게 나타났다.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.14 no.1
• /
• pp.32-39
• /
• 2011

When the laws about the security of ships are revised, or voyage conditions are changed, ship owners have converted rather than built new passenger ships including cruise ships recently. As conversion causes a lot of changes in principal dimension, structural strength, hydrodynamic performance, the number of passengers, and cargo capacity, detailed pre-review is needed. But any studies on conversion have not been carried out yet, this study investigated and analyzed the trend of consulting companies' reports (Delta Marine Report, 2005, 2008). As a result, it was found that lengthening conversion brought about the main changes in principal dimension, and performance. Also it was suggested that there be factors for consideration like hull scantling, hull form, and cutting point to minimize side effects when ship owners build ships having lengthening conversion in mind.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.51 no.1
• /
• pp.61-70
• /
• 2015

In an attempt to improve the maneuvering character of hull form renovated tuna purse seiner. A renovation was carried out on the 3 tuna purse seiner fishing vessel. To grasp the progress of maneuvering and resistance on ship B (730 ton class), new bulbous bow was only attached. The ship A (740 ton class) and C (600 ton class) were modified for new bulbous bow, enlarged slipway and rudder. And then the zigzag and the turning test were carried out. According to the turning test, the advance and the tactical diameter were improved very much for the modified ship. The sea trial was carried out for the original and modified ship A. It is showed that the results of sea trial corresponded with that of the tank test on the whole. In the result of the zigzag test on ship B, the turning ability was improved very much, but the yaw checking ability was deteriorated in just some degree. In the result of the zigzag test on ship C, the turning ability and yaw checking ability were remarkably improved. Ship C was greatly improved among the three ships for the maneuvering character of modified hull form.

• Proceedings of the KIPE Conference
• /
• 2011.07a
• /
• pp.115-117
• /
• 2011

포항가속기연구소에서 성능향상사업으로 2.5 GeV에서 3.0 GeV로 에너지를 증강하는 사업을 추진중에 있다. 선형가속기의 전자를 가속하기 위하여 필요한 에너지 공급 장치로서 RF 증복기인 80 MW 클라이스트론과 200 MW 펄스 전원공급장치가 필요하다. 성능향상사업으로 전자를 가속하기 위하여 기존의 12set중 4set는 개조하고 4set는 추가하는 방안으로 16set의 200 MW 펄스 전원공급장치를 설치하여 운전 중에 있다. 그중 8set는 3상 AC/AC 위상제어 방식을 사용한 SCR 제어기의 출력을 승압트랜스퍼머 및 정류회로를 이용하여 고전압의 직류를 피드백 받아 일정한 펄스 전원을 공급하기 위해 설치후 시험중에 있다. 펄스를 부하로 전달시 발생하는 노이즈한 환경에서 SCR Controller의 제어방식과 설치하여 시험한 결과를 검토하고자 한다.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.26 no.4
• /
• pp.369-379
• /
• 1993

Using a successive removal approach the mechanism of sampling capture efficiency of blue crabs by dredges was studied in Chesapeake Bay during winter 1992. For the twenty-six field experiments no significant statistical differences were detected in dredge efficiency using general linear model analysis by factors including bottom sediments, water depths, and sampling vessels. Dredge efficiency (i.e., catchability) was estimated by two methods, Leslie (Leslie and Davis, 1939) and a simple revised method. Mean catchability was estimated at 0.26 (SE=0.03), indicating that only $26\%$($95\%\;C. I.=20{\sim}32\%$) of crabs present in the path of the dredge of a given sampling area are caught with a single dredge tow. Dredge efficiency declined exponentially as crab density increased.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.51 no.3
• /
• pp.321-332
• /
• 2015

In an attempt to find the improvement of the fishing efficiency according to the hull form remodeling for the 3 tuna purse seiner, the Catch-Per-Unit-Effort (CPUE) for that undertaken before (2008) and after (2010) was analyzed. In addition, the CPUE of 6 similar ships operated same period and same fishing ground. As result, it came to verify that the three modified ships had a significant value on the CPUE. An another index for the improvement of fishing efficiency is the rate of reduction of fuel oil consumption for the modified ships. Fuel oil consumption per day in service speed as comparing with the original ships were reduced 2.1%, 4.0% and 5.1% on the modified ship A, B, and C respectively. And each ship's service speed was increased 1.0 kt, 0.6 kt, and 0.4 kt according to the modified ship A, B, and C in due order. In the conclusion, the remodeling job with newly equipped bulbous bow, lengthened slipway and enlarged rudder area were improved fairly much on fuel oil efficiency, the ship's speed, and in the end, that led to the improving fishing efficiency. Hence, the remodeling of tuna purse seiner come to improve not only the fishing performance, but contribute to the reduction of operating cost by saving energy for the fisheries industry.