• 한국해양공학회지
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• 제35권6호
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• pp.446-456
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• 2021

To build an environment facility of a large-scale ocean basin, various detailed reviews are required, but it is difficult to find data that introduces the related research or construction processes on the environment facility. The current generator facility for offshore structure safety evaluation tests should be implemented by rotating the water of the basin. However, when the water in the large basin rotates, relatively large flow irregularities may occur and the uniformity may not be adequate. In this paper, design and review were conducted to satisfy the performance goals of the DOEB through computational numerical analysis on the shape of the waterway and the flow straightening devices to form the current in the large tank. Based on this, the head loss, which decreases the flow rate when the large tank water rotates through the water channel, was estimated and used as the pump capacity (impeller) design data. The impeller of the DOEB current generator was designed through computational numerical analysis (CFD) based on the lift surface theory from the axial-type impeller shape for satisfying the head loss of the waterway and maximum current velocity. In order to confirm the performance of the designed impeller system, the flow rate and flow velocity performance were checked through factory test operation. And, after installing DOEB, the current flow rate and velocity performance were reviewed compare with the original design target values. Finally, by measuring the current velocity of the test area in DOEB formed through the current generator, the spatial current distribution characteristics in the test area were analyzed. Through the analysis of the current distribution characteristics of the DOEB test area, it was confirmed that the realization of the maximum current velocity and the average flow velocity distribution, the main performance goals in the waterway design process, were satisfied.

• 한국해양공학회지
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• 제35권2호
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• pp.150-160
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• 2021

To ensure the international competitiveness of the domestic offshore plant industry, a consensus has been formed regarding the requirement for large offshore basins for performing offshore plant performance verification. Accordingly, the Korea Research Institute of Ships & Ocean Engineering has built the world's largest deep ocean engineering basin (DOEB). The purpose of this study is to evaluate the characteristics of velocity distribution under various conditions of the DOEB. An independent measuring jig is designed and manufactured to measure the current velocities of many locations within a short time. The measurement jig is a 15-m-high triangular-truss structure, and the measurement sensors can move 15 m vertically through an electric motor-wire device. The current speed is measured under various impeller revolutions per minute and locations of the DOEB using the jig. The spatial distribution characteristics of the current velocity in the DOEB and the performance of the current generator are analyzed. The maximum speed is 0.56 m/s in the center of the DOEB water surface, thereby confirming sufficient current velocity distribution uniformity for model testing.

• 한국해양공학회지
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• 제22권3호
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• pp.64-70
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• 2008

A full-scale field experiment is an important part in the design of ships and offshore structures. Full-scale tests in the ice-covered sea, however, are usually very expensive and difficult tasks. Model tests in a refrigerated ice tank may substitute this difficulty of full-scale field tests. One of the major tasks to perform proper model tests in an ice towing tank is to select a realistic material for model ice which shows correct similitude with natural sea ice. This study focuses on the testing material properties and the selection of model ice material which will be used in an ice model basin. The first Korean ice model basin will be constructed at the Maritime & Ocean Engineering Research Institute (MOERI) in 2009. With an application to the MOERI ice model basin, in this study the material properties of EG/AD/S model ice of IOT (Institute for Ocean Technology) Canada, were tested. Through comprehensive bending tests, the elastic modulus and the flexural strength of EG/AD/S model ice were evaluated and the results were compared with published test results from Canada. Instead of using an ice model basin, a cold room facility was used for making a model ice specimen. Since the cold room adopts a different freezing procedure to make model ice, the strength of the model ice specimen differs from the published test results. The reason for this difference is discussed and the future development for a making model ice is recommended.

• 한국산업융합학회 논문집
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• 제27권3호
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• pp.629-634
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• 2024

The Korea Research Institute of Ships and Ocean Engineering (KRISO) has developed a test module that can vertically ascend and descend with a buoyancy engine to verify the performance of the developed buoyancy engine. The independent test module has been tested in the Ocean Engineering Basin(C.M.Lee et al., 2023). After that, more tests were performed in the Deep Ocean Engineering Basin and at sea. In the 50-meter depth pit test of the Deep Ocean Engineering Basin, there were no problems with the ascent and descent operations, but the buoyancy engine was not properly maintained due to various problems in the independent test module, resulting in a difference between the calculated results using the solution of the equations of motion and the actual measurement results. The East Sea test was conducted at a depth of approximately 110 meters north-east of Pohang, with a dive to 100 meters. The difference between the pressure sensor value and the calculated value was observed, but after checking the results of the underwater position tracking device(USBL, Ultra Short Base Line system), it was estimated that the difference was caused by the influence of the current.

• Ocean and Polar Research
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• 제43권4호
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• pp.295-306
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• 2021

A field scale productivity analysis is required for the development of gas hydrate in marine sedimentary layers to verify the field applicability of production techniques and to improve productivity. In this study, the productivity resulting from the application of depressurization using multi-wells for the development of gas hydrate in the Ulleung Basin, East Sea of Korea, was determined. A numerical analysis model reflecting the conditions of candidate sites for the Ulleung Basin was constructed, and the productivity and dissociation behavior were comparatively analyzed. The pressure propagation and gas hydrate dissociation region by the multi-wells were wider and the productivity was higher than that of a single well. Different depressurization effects according to the spacing of multi-wells affected productivity. The results provide basic data for productivity analysis when establishing a field test production plan for the Ulleung Basin.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.355-358
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• 2006

An underwater mooing target position tracking system using image tracking system of CPMC is developed to use in a test basin. Generally the performance tests of Autonomous Underwater Vehicles(AUVs) are conducted in the sea. Some efforts to perform the test in a test basin are exist, because the real sea tests need much time and manpower. And also the real sea tests are high cost. There is a restriction to acquire the position of AUVs using sonar sensor system in the test tank, because many sound reflecters are exist in a test basin. In this paper a position tracking system for underwater mooing target developed to break though this restriction. A Tank-test is conducted to examine the performance of the position tracking system.

• 한국항해항만학회지
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• 제46권6호
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• pp.471-482
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• 2022

본 연구는 심해공학수조의 파 생성 특성을 규명하고, 심해공학수조의 기하학적 특성을 반영한 조파기 전달함수의 근사모델을 개발하는 것을 목적으로 한다. 심해공학수조의 기하학적 특성을 반영한 효율적인 해석을 위해 2차원 주파수영역 경계요소법이 적용되었다. 개발된 수치해석법은 해석해와 비교하여 검증되었다. 다양한 주기와 이동식 바닥판의 위치 변화에 대한 조파기의 경계치 문제의 수치해석이 수행되었다. 수치결과를 통해 심해공학수조의 기하학적 특성이 조파기의 전달함수에 미치는 영향을 조사하였고, 이동식 바닥판의 위치를 변화시켜 파도 생성에 대한 깊이 효과를 확인하였다. 경계요소법의 다양한 결과를 효율적으로 활용하기 위해 박판 스플라인 보간 모델 기반의 조파기 근사모델을 개발하였다. 개발된 근사 모델의 타당성은 모델 테스트 결과 비교를 통해 확인하였다.

• Journal of Advanced Research in Ocean Engineering
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• 제1권4호
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• pp.227-238
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• 2015

The present work was an attempt to investigate the applicability of truncated mooring systems to KRISO's deep ocean engineering basin (DOEB) with ratios of 1:100, 1:60, and 1:50. The depth of the DOEB is 15 m. Therefore, the corresponding truncated depths for this study were equal to 1500 m, 900 m, and 750 m. The investigation focused on both the static and dynamic characteristics of the mooring system. It was shown, in a static pull-out test, that the restoring force of a FPSO vessel could be modified to a good level of agreement for all three truncation cases. However, when the radius of the mooring site was reduced according to the truncation factor, the surge motion response during a free-decay test showed a significant difference from the full-depth model. However, the reduction of this discrepancy was achieved by increasing the radius up to its maximum possible value while considering the size of the DOEB. Especially, in terms of the time period, the difference was reduced from 24.0 to 5.3 s for a truncation ratio of 1:100, 54.1 to 8.6 s for a truncation ratio of 1:60, and 31.7 to 3.9 s for a truncation ratio of 1:50. As a result, the study verified the applicability of the truncated mooring system to the DOEB, and therefore it could represent the full-depth mooring system relatively well in terms of the static and dynamic conditions.

• 대한조선학회논문집
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• 제54권1호
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• pp.49-56
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• 2017

Recently, many research works on the icebreaking vessels have been published as the possibility of passing Arctic routes has been increasing. The model ship test on the pack ice model in the ice basin is actively carried out as a way to investigate the performance of icebreaking vessels. In this test, the concentration of pack ice is important since it directly affects the performance. However, it is difficult to measure the concentration because not only the pack ice has uneven shape but also it keeps floating around in the basin. In this paper, an algorithm to identify the concentration of pack ice is introduced. From a digital image of pack ice obtained in the ice basin, the goal is to measure the area of pack ice using an image processing technique. Instead of the general global binarization that yields numerical errors in this problem, a local binarization technique, coupled with image subdivision based on the quadtree structure, is developed. The concentration results obtained by the developed algorithm are compared with the manually measured data to prove its accuracy.

• 한국해양공학회지
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• 제19권3호
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• pp.47-53
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• 2005

Model for dust and salt transportation from the dried bottom of the Aral Sea is suggested. Theoretical analysis is based on the turbulent diffusion equation for the averaged function of passive impurity concentration. One-layer model of the atmospheric boundary layer is assumed. Impurity precipitation rates are calculated as the functions of the particle size and the distance source of particles. Analytical solutions for the point and two-dimensional sources of impurities are found. Model calculations for salt and sand transport from the Aral Sea basin are made on the basis of 2D source model with a constant intensity.