• 한국농공학회논문집
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• 제57권5호
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• pp.101-111
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• 2015

Establishment of appropriate data in certain formats is essential for agricultural water cycle analysis, which involves complex interactions and uncertainties such as climate change, social & economic change, and watershed environmental change. The main objective of this study was to develop web-based Data processing and Model linkage Techniques for Agricultural Water-Resource analysis (AWR-DMT). The developed techniques consisted of database development, data processing technique, and model linkage technique. The watershed of this study was the upper Cheongmi stream and Geunsam-Ri. The database was constructed using MS SQL with data code, watershed characteristics, reservoir information, weather station information, meteorological data, processed data, hydrological data, and paddy field information. The AWR-DMT was developed using Python. Processing technique generated probable rainfall data using non-stationary frequency analysis and evapotranspiration data. Model linkage technique built input data for agricultural watershed models, such as the TANK and Agricultural Watershed Supply (AWS). This study might be considered to contribute to the development of intelligent watercycle analysis by developing data processing and model linkage techniques for agricultural water-resource analysis.

• 대한조선학회논문집
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• 제53권1호
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• pp.37-44
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• 2016

Recently researchers are conducting a lot of research related to EEDI in order to satisfy IMO resolution MEPC. Especially they are interested in design of energy saving device. This paper is to design the asymmetric pre-swirl stator for 160K LNG carrier in order to reduce energy. Two types of the asymmetric pre-swirl stator are taken into account; constant and variable pitch angle stators. “constant” and “variable” mean state that the pitch of stators change by radius. The dimensions of the stators are initially determined using potential-flow code. The propulsion performances of the stators are predicted using viscous-flow code. The model test is carried out in towing tank in PNU. Prediction of ship performance generally follow ITTC recommended. Ship wake prediction was done by two method, ITTC 1978 and ITTC 1999. Therefore propulsion performances were compared ITTC 1978 with ITTC 1999 methods. Comparison components are delivered power and thrust deduction coefficient of the model. Final pre-swirl stator is selected by comparing experiment and CFD.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.159.2-159.2
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• 2011

Hyundai Heavy Industries has developed a tidal current energy converter utilizing the accumulated technology as the world largest constructor for ship and offshore structures. The model has two sets of turbines in both ends in order to utilize the bi-directional current flows in flood and ebb tide. The torque produced by turbine in tidal current is directly delivered to generator along the horizontal axis, in which the turbine, gear, generator, gear and turbine are connected successively. The manufactured model for field test has the turbine diameter of 5 meters to produce the maximum power of 500kW at maximum current speed of 5m/s. The technical verification of tidal power converter was performed by means of small scale model test in towing tank as well as field test at the Strait of Uldolmok located in Jindo of Jeollanamdo province. Field test was performed by mounting the tidal current converter on the SEP(Self Elevating Platform) which could lower the 4 vertical legs on the seabed and could elevate platform over the water surface using the hydraulic power for itself. The field test performed for a month shows that power output is similar or larger compared with the expected one in design stage. This paper presents the development of tidal current energy converter and real sea field test by Hyundai Heavy Industries. This project has finished successfully and provided the technical advance toward commercial services for tidal current power generation in the south-west region in Korea.

• Spatial Information Research
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• 제14권1호
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• pp.57-65
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• 2006

일반적으로 퇴적물 준설에 대한 조사는 GPS/Echo Sounder 및 Total Station/Echo Sounder를 조합한 음파탐사 방법을 이용하여 대상지의 수평위치 및 수심에 대한 관측을 실시하고 있으며, 하상의 단면계산, 저수량 및 준설계획량 등을 추정하게 된다. 이후 준설계획에 대한 계획고 및 준설토량에 대한 세부적인 계획을 수립하게 된다. 하지만 Echo Sounder를 사용하는 음파탐사 방법은 퇴적물에 대한 정확한 분포를 파악할 수 없는 단점이 있다. 본 연구는 저수지 하부의 퇴적물 및 이의 분포를 파악하여 저수지 준설계획을 수립하여 기존의 탐사방법에 대한 준설능력 향상에 중점을 두었다. 또한 기존의 음파탐사 방식과 다른 레이더탐사 장비를 이용한 GPS/GPR(Ground Penetration Radar)을 사용하여 저수지의 수평위치, 수심값을 결정하고 동시에 원지반에 분포하고 있는 퇴적물의 분포를 추정, 준설에 적용하고자 하였다. 우선 현장의 시료채취를 통한 수조모형실험을 실시하여 장비에 대한 정확도 검증을 거친 후 현장적용에 적용하여 그 가능성을 평가하였다.

• 대한조선학회논문집
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• 제49권5호
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• pp.367-375
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• 2012

In this study, hull form of main vessel of Korean large purse seiner fishing industry is developed for the improvement of resistance performance as well as for the satisfaction to the Standard of Fishing Convention, ILO. Through the modification of reference hull form parameters and local characteristics, the hull form development is carried out. The optimum hull form parameters are searched by Sequential Quadratic Programing(SQP) method with the power estimation method of Holtrop & Mannen. To minimize the wave resistance, bulbous bow parameters are determined by the bulbous bow design method of Alvarino. The plasmatic curve is redesigned from that of the reference hull by using Lackenby method. The resistance performances of the reference and designed hull forms are estimated by using numerical simulation method. Also, the judgment of seakeeping ability and the estimation of intact stability for the designed hull form is carried out. As a result, the optimum hull form is proposed. To verify the improvement of resistance performance, model tests are carried out in towing tank. The results show that the resistance of the designed hull form is about 14% smaller than that of the reference hull from at design speed. A new hull form proposed in this study can contribute to the development of the main vessel hull form of Korean large purse seiner fishing system.

• 대한조선학회논문집
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• 제49권5호
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• pp.416-424
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• 2012

The MAU series has been usually used for the fishing vessel's propeller, which has been improved in consideration of the efficiency as well as the cavitation point of view in Pusan National University. The high efficiency standard series propeller(KF series) has been applied to the design of 52ton class fishing vessel's propeller in the previous study. The experimental study for the performance of the design propellers called KF series for 52 ton class fishing vessel has been conducted with five cases in Korea Ocean Research & Development Institute towing tank. The model tests have been carried out at different pitch ratio and expanded area ratio in comparison with the standard propeller to make the series chart. The KF series chart and the formula for performance expression have been completed on the basis of the experiment result.

• 한국음향학회지
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• 제33권3호
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• pp.174-183
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• 2014

능동소나에 의한 표적 반향 신호는 다중경로 환경에서 전파됨에 따라 신호가 변형되어 수신된다. 또한 표적의 위치와 자세각에 따라 반향 신호 특성이 다르게 나타난다. 따라서 이러한 특성을 반영할 수 있는 3차원 형상의 표적 모델을 통해 반향 특성이 모의 되어야 한다. 본 논문에서는 3차원 표적신호의 모의를 위해 표적의 각 구성부를 형상 함수화 하였으며 각 구성부의 대표 반향점을 등간격으로 선정하여 표적 모델을 개발하였다. 개발된 표적 모델을 이용하여 음의 입사각에 따른 반향 신호와 표적강도(TS : Target Strength)를 모의하였다. 모의된 표적신호의 반향 강도 및 신호 특성을 검증하기 위해 조립이 가능한 구성부별 축소 모형을 제작하여 수조에서 축소 표적을 이용한 반향 실험을 수행하였다.

• 대한조선학회논문집
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• 제51권5호
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• pp.369-379
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• 2014

Planing hull forms have significant influences on those hydrodynamic performances in calm water and in waves. Therefore, the hydrodynamic performance of a planing vessel should be predicted by model tests or theoretical calculations, and be confirmed whether it shows the performance requirements at the design stage. In this study, four planing hull forms are designed with the goal of the improvement of resistance and seakeeping performance, and 1/6.5 scale model tests are carried out in Seoul National University towing tank. The effects of design parameters such as length-to-beam ratio, deadrise angle and forebody shape on the hydrodynamic performance are investigated, based on model test results. Running attitude and resistance of model ships in calm water are also estimated by empirical formulae proposed by Savitsky (1964; 2007; 2012), and compared with the model test results. It is shown that calm water performance of non-prismatic planing hulls can be predicted well by Savitsky (2012)'s formula which improves the original Savitsky(1964/2007)'s formula by taking into account the variations of deadrise angles, and the actual angles between the hull bottom and the free surface.

• 대한조선학회논문집
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• 제53권5호
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• pp.371-379
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• 2016

In the ship design process, ship motion and propulsion performance in sea waves became very important issues. Especially, prediction of ship propulsion performance during real operation is an important challenge to ship owners for economic operation in terms of fuel consumption and route-time evaluation. Therefore, it should be considered in the early design stages of the ship. It is thought that the averaged value and fluctuation of effective inflow velocity to the propeller have a great effect on the propulsion performance in waves. However, even for the nominal velocity distribution, very few results have been presented due to some technical difficulties in experiments. In this study, flow measurements near the propeller plane using a stereo PIV system were performed. Phase-averaged flow fields on the propeller plane of a KVLCC2 model ship in waves were measured in the towing tank by using the stereo PIV system and a phase synchronizer with heave motion. The experiment was carried out at fully loaded condition with making surge, heave and pitch motions free at a forward speed corresponding to Fr=0.142 (Re=2.55×106) in various head waves and calm water condition. The phase averaged nominal velocity fields obtained from the measurements are discussed with respect to effects of wave orbital velocity and ship motion. The low velocity region is affected by pressure gradient and ship motion.

• 대한조선학회논문집
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• 제42권3호
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• pp.197-204
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• 2005

A waterjet propulsion system has many advantages compared with a conventional screw propeller especially for amphibious armored wheeled vehicles because of a good maneuverability at low speed, good operation ability at shallow water, high thrust at low speed to aid maneuverability and exit from water, etc. The POD type waterjet is adequate for the present wheeled vehicle because the weight is lighter and L/B is longer than the conventional armored amphibious vehicle. Resistance and self-propulsion tests with a 1/3.5-scale model are conducted at PNU towing tank. Based on these measurements, the performance is analyzed according to ITTC 96 standard analysis method and also according to the conventional propulsive factor analysis method. Based on these two methods, the full-scale effective and delivered powers of amphibious armored wheeled vehicle are estimated. This paper emphasizes the analysis method of model test of the waterjet propulsion system for a amphibious armored wheeled vehicle and the model test technique together with the comparison of the two analysis methods.