• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.6
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• pp.774-780
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• 2014

This research aims to investigate the superstructure characteristics of the CFRP-yachts whose hulls are made of the light-weight material CFRP. CFRP-yachts, which belong to light-weight yachts, have a tendency of having very small superstructures compared to other vessels of the same length, and such a tendency is closely related to stability. In this research, a comparison of shape characteristics was made between common composite-plastic yachts and CFRP-yachts to find out the shape characteristics of CFRP-yacht. In the meantime, a case study was conducted concerning shape changes in superstructure to understand the effect of such changes on stability. For this purpose the shapes of a total of 10 GFRP-yachts and CFRP-yachts were comparatively analyzed, and the result showed the tendency of their hulls and superstructures. Whereas the case study on stability assessment involved various superstructure shapes of CFRP yachts, for assessment by superstructure size. Stability assessment was according to ISO 12217 (Small craft Stability and buoyancy assessment and categorization). A program was also developed based on stability assessment process due to rolling in beam waves and wind, and it was applied to the case study. The result of the case study showed that the windage area distribution tendency of the yachts whose hulls were made of the light-weight material CFRP was similar to that of the GFRP-yachts, but that the superstructure shapes of the CFRP-yachts were about 50% smaller than those of the GFRP-yachts. In addition, the stability assessment involving various superstructure areas of the CFRP-yachts showed that problems with stability occurred when their superstructure sizes were similar to, or larger by about 10% than, those of the GFRP-yachts.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.299-301
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• 2012

제주 강정항은 우리나라 남방해역의 보호라는 안보적인 측면과 대형 크루즈선 유치를 통한 관광산업의 활성화를 위해 해군기지와 민항의 기능을 가진 민 군복항으로 건설되고 있다. 본 연구에서는 제주 강정항 계류시설의 대상선박인 15만톤급 초대형 크루즈선의 입 출항 및 통항 안전성 판별을 위해 실시하는 선박조종시뮬레이션의 일반 수행 절차와 선행 연구 등을 분석한다. 이는 선행 연구에서 제기된 주요 쟁점사항들을 명확하게 분석함으로써 객관적이고 신뢰성 높은 선박조종시뮬레이션 연구를 수행하고자 하는 것으로, 주요 검토 사항은 수역시설인 선회장과 진입항로의 교각, 크루즈선의 풍압면적과 적용 풍속 등을 면밀하게 고찰하여 시뮬레이션에 반영하고자 함이다. 또한 제주 강정한 건설은 사회적 관심이 매우 큰 국책사업임을 감안하여 선박조종시뮬레이션 분석 및 평가 등에 해상교통안전 및 선박운용 분야의 전문가그룹을 자문위원으로 구성했고, 연구 결과의 타당성 확보를 위해 해상교통안전진단제도에 명시된 선박조종시뮬레이션 표준절차와 평가 방법 등을 적용하였다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.2
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• pp.172-178
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• 2014

This study suggests the minimum critical external forces based on the assessment of anchoring safety to single anchor situation for representative 8 number of ships in E-group anchorage of Ulsan port. Assessment of anchoring safety is compared holding powers of anchor with external forces of wind, wave and current. Holding powers was reflected materials of seabed, equipment numbers regarding anchor and chain weight, also external forces acting on a hull was calculated considering projected wind area and wetted surface area to the full and ballast conditions respectively. The results of anchoring safety assessments to single anchor showed that the minimum criteria of dragging anchor is a little different from ship's type, size and loading conditions. Bulk carrier can be dragged over the 15m/s of winds and Tanker can be dragged over the 13m/s of winds in case of less than 2knots of currents speed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.3
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• pp.223-228
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• 2009

By the typhoon "MAEMI" in 2003, a lot of marine accidents such as stranding, collision etc. occurred to the vessels at anchor in "JINHAE MAN" which was considered one of the most safe sheltering anchorage in Korea. These accidents resulted from the dragging of anchor by the strong winds. It needs to compare the external forces with the holding powers of anchors to estimate if the anchor will be dragged or not. However, the calculation of the force by the wind on the ship, in particular, on the wind pressure area which changes by the swinging of her bow is not yet set on a thesis. Therefore, this paper verified that how many times the front wind pressure area should be applied to calculate the force by the wind on the ship at anchor by comparing and analyzing the numerical calculation with, the actual ship's data which was really dragged by the strong wind.

• Journal of Korean Association for Spatial Structures
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• v.9 no.4
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• pp.81-88
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• 2009

Damage on low?rise buildings caused by typhoons and storms is increasing every year. Thus, this study examined the distribution of wind pressure coefficient at each position according to the height of monosloped roof, and measured wind pressure coefficient according to tributary area and compared it with the current wind load standard. We analyzed six areas in order to analyze characteristics at each position of a half span roof, and found that the wind pressure coefficient was around 25% higher at the high comer (HC) than at the low corner (LC). The distribution pattern of peak pressure coefficient at each position was the same as the AIK load standard, but in the results of our experiment, wind pressure was around 40% lower than the load standard at HC and around 37% higher than the load standard at LC.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.639-646
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• 2016

In order to establish an operational standard based on ship size, this study considered a specific safety management plan for Ulsan along with international standards, analyzed the results of mooring safety assessment at four vulnerable piers and suggests cargo stoppage and emergency unberthing standards as follows. In accordance with ship characteristics, ships of less than 10,000 tons are recommended to limit their activities for wind speeds of 18-21 m/s and wave heights of 1.0-1.5 m. Ships from 10,000-50,000 tons are recommended to observe wind speeds of 17-20 m/s and wave heights of 1.2-1.5 m, while, ships of 50,000-100,000 tons are recommended wind speeds of 15-19 m/s and wave heights of 1.5 m. Ships of more than 100,000 tons are recommended wind speeds of 14-18 m/s and wave heights of 1.5 m.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.280-281
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• 2017

본 논문에서는 기존의 배풍기 효율을 높이고 크기를 줄이기 위해 임펠러의 속도를 높이는 설계에 관한 연구다. 임펠러 속도는 5500rpm으로 증가시키고 크기는 320mm에서 250mm로 줄였으며 효율과 최대 풍량을 향상키기기 위해 임펠러의 Hub/Tip 비율을 줄이며, 날개각도에 변화를 주는 방식을 제안한다. Hub/Tip 비율이 줄어들면 유량이 통과하는 면적이 넓어지게 되는 효과를 얻게 되고, 임펠러 중심거리에 따른 날개 각도를 변화시키면 풍압과 풍량이 달라지는 효과를 얻게 되어 동일한 rpm으로 회전하는 배풍기의 효율을 높일 수 있다. 설계된 구동용 SRM과 임펠러의 설계에 따른 운전 특성을 시뮬레이션을 통해 해석하고자 한다.

• Journal of Navigation and Port Research
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• v.33 no.8
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• pp.505-511
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• 2009

Vessels on anchoring are frequently dragged due to the increased area of wind pressure by enlargement of ship's size and sudden gust of winds in recent years. In the view point of the ship's navigators, the proper measurements corresponding to the dragging of anchor should be taken into account concerned about the time for the occurring of dragging by the external forces such as wind and wave, the pattern and speed of dragging and the possibility of collisions with any other vessels or obstacles. In this paper, it was examined the actual dragging anchor in T.S. HANBADA due to the wind and waves. From this case, it was found the critical external forces by which she was begun to dragged comparing the force by the wind, frictional resistance, drifting force and ship motion moment with the holding power. Also, through the analysis of the dragging pattern, it was known the alteration range of heading angle, swinging width and dragging speed etc.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.81-82
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• 2017

기존의 배풍기 효율을 높이기 위해서 모터와 제어방식 그리고 임펠러 형상에 변화를 주는 시스템 설계에 관한 연구다. 본 논문에서는 임펠러 속도는 5500rpm으로 증가시키고 크기는 320mm에서 250mm로 줄였으며 효율과 최대 풍량을 향상키기기 위해 임펠러의 Hub/Tip 비율을 줄이며, 날개각도에 변화를 주는 방식을 제안한다. 여기서 Hub/Tip 비율이 줄어들면 임펠러 날개의 면적이 늘어나 유량이 증가하게 되고, 임펠러 중심 거리에 따른 날개 각도를 변화시키면 배풍기 속도에 대한 풍압과 풍량이 달라져 배풍기의 효율을 높일 수 있다. 설계된 구동용 SRM과 임펠러의 설계에 따른 운전 특성을 시뮬레이션을 통해 해석하고자 한다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.857-862
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• 2023

In order for an autonomous ship to arrive near the pier and automatically berth without the help of a tugboat or pilot, it is necessary to recognize the pier and calculate the thruster output and output angle for berthing to the pier at a fixed berthing speed under given external force conditions. Therefore, in this study, the external force and moment acting on the ship while berthing were analyzed, and the thruster output calculation for automatic berthing was designed and the basic concept for the development of the automatic berthing program was designed. The wind pressure applied to the hull by the wind while the ship is berthing was calculated based on the wind pressure area and the wind direction angle and the turning moment to rotate the ship according to the transverse force of the ship was calculated. Considering the force acting on the ship and the turning moment during berthing, a theoretical formula was presented to calculate the thruster output and output angle for berthing parallel to the pier, and the turning due to other variables was controlled by the PID controller. In addition, the basic concept for program development was presented by analyzing the input elements necessary for the theoretical formula.