• Journal of the Society of Naval Architects of Korea
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• v.40 no.4
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• pp.37-45
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• 2003

Model tests using 2.0m model of the series 60 form( $C_{b}$= 0.6) were carried out in the Circulating Water Channel (CWC) in the Chosun University (CU, Korea) for the purpose of a correlative study with Towing Tank (TT). Resistance, propeller open water, self propulsion and wake survey tests were carried out and the results were extrapolated to the ship scale. These results were compared with the extrapolated ship values based on the model test of 7.0m model in the TT at the Korea Research Institute of Ships and Ocean Engineering (KRISO, Korea). The CWC test results were correlated with the results of the towing tank tests.s.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.70-75
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• 2003

Model tests using 2.0m model of the series 60 form ($C_{b}$ = 0.6) were carried out in the Circulating Water Channel(CWC) in the Chosun University(CU, Korea) for the purpose of a correlative study with Towing Tank(TT). Resistance, propeller open water, self propulsion, and wake survey tests were carried out and the results were extrapolated to the ship scale. These results were compared with the extrapolated ship values based on the model test of 7.0m model in the TT at the Korea Research Institute of Ships and Ocean Engineering (KRISO, Korea). The CWC test results were correlated with the results of the towing tank tests.

• Journal of Ocean Engineering and Technology
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• v.11 no.3
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• pp.100-106
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• 1997

Despite various devices have been developed and applied to stabilize the yaw motion, the superiority of twin skeg over other equi-functioned appendages has been recognized so far. In many cases, these skegs were installed with insufficient study and analysis for design, and this leads to the worse performance of their resistance and course keeping than required. Experimental studies on the effect of various kinds of anti-yawing skegs to the course keeping stability and on the additional resistance caused by them were carried out in the circulating water channel(CWC) at Chosun University(CU). Course keeping stability tests for four different size of skegs, resistance tests for three different shapes of skeg(including deformed skegs) were performed systematically. And the effect of angle of skegs on resistance was studied at the final stage.

• Journal of Ocean Engineering and Technology
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• v.26 no.4
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• pp.37-41
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• 2012

Due to global warming, the need to secure alternative resources has become more important nationally. Because of the very strong current on the west coast, with a tidal range of up to 10 m, there are many suitable sites for the application of TCP (tidal current power) in Korea. In the southwest region, a strong current is created in the narrow channels between the numerous islands. A rotor is an essential component that can convert tidal current energy into rotational energy to generate electricity. The design optimization of a rotor is very important to maximize the power production. The performance of a rotor can be determined using various parameters, including the number of blades, shape, sectional size, diameter, etc. There are many offshore jetties and piers with high current velocities. Thus, a VAT (vertical axis turbine) system, which can generate power regardless of flow direction changes, could be effectively applied to cylindrical structures. A VAT system could give an advantage to a caisson-type breakwater because it allows water to circulate well. This paper introduces a multi-layer vertical axis tidal current power system. A Savonius turbine was designed, and a performance analysis was carried out using CFD. A physical model was also demonstrated in CWC, and the results are compared with CFD.

• New & Renewable Energy
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• v.8 no.1
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• pp.44-51
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• 2012

Due to a high tidal range of up to 10 m on the west coast of Korea, numerous tidal current projects are being planned and constructed. The turbine, which initially converts the tidal energy, is an important component because it affects the efficiency of the entire system. Its performance is determined by design variables such as the number of blades, the shape of foils, and the size of a hub. To design a turbine that can extract the maximum power on the site, the depth and duration of current velocity with respect to direction should be considered. Verifying the performance of a designed turbine is important, and requires a circulating water channel (CWC) facility. A physical model for the performance test of the turbine should be carefully designed and compared to results from computational fluid dynamics (CFD) analysis. In this study, a horizontal axis tidal current turbine is designed based on the blade element theory. The proposed turbine's performance is evaluated using both CFD and a CWC experiment. The sealing system, power train, measuring devices, and generator are arranged in a nacelle, and the complete TCP system is demonstrated in a laboratory scale.

• Journal of The Korean Society of Grassland and Forage Science
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• v.5 no.1
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• pp.84-89
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• 1985

Chemical composition, dry matter and cellulose digestibilities and fermentation rates of alfalfa and orchard grass cut at different time were estimated in vitro method and the results summurized as follows: 1. Crude protein, crude fiber cwc and cellulose content of Alfalfa were decreassed as advancing cutting time. Crude protein, crude fiber and cwc content of Orchard grass were decreased as advancing cutting time up to 3 cutting, but crude protein was slightly increased at 4th cutting, crude fiber and cellulose content were higher at 2nd cutting, but decreased thereafter. 2. DM digestibility of Alfalfa was 51.80, 51.86, 52.92 and 59.52% at 1, 2, 3 and 4th cutting time, respectibly, thus slightly increased as advancing cutting time, and cellulose digestibility of Alfalfa was not much different with different cutting time. DM digestibility of Orchard grass was 62.21, 66.10, 60.95 and 66.32% at 1, 2, 3 and 4th cutting time, respectibly, and cellulose digestibility of Orchard grass was slightly increased at 3rd cutting time and then increased at 4th cutting time. 3. Fermentation rate of DM of alfalfa was the highest 1st cutting time (0.83%/hr.) and was not different at 3 and 4th cutting time. Cellulose fermentation rate of Alfalfa was the highest at 1st cutting time (1.29%/hr.), decreased at 2 and 3th and then increased at 4th cutting time. Fermentation rate of DM of Orchard grass was 1.42, 1.58, 1.60 and 1.57%/hr. and of cellulose was the highest at 2nd cutting time (1.77%/hr.)

• Defense and Technology
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• no.9 s.235
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• pp.66-73
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• 1998

세계적으로 화학, 생물학 및 방사능 무기의 근절을 위해 CWC와 같은 여러 가지 국제조약이 결성되고 있으나 힘의 논리와 자국 이익의 논리가 앞서는 한 근본적인 근절은 어려운 실정이다. 이 글에서는 화생방전의 피해를 최소화하기 위한 통합 시스템을 소개하고 각 시스템에서 필요한 기술을 나열하였다. 특히 이러한 기술들 중에서 많은 부분이 원자력 분야에서 개발되었으나 개발 중이어서 군용으로의 전환이 용이할 것으로 기대된다.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.2
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• pp.198-204
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• 2011

This paper presents the experimental result to investigate the characteristics of turbulent wake generated by submarine. A SUBOFF nude model which was assumed as an axial -symmetric body was used to create wake, and a thin strut was mounted on the top of the model. The experiments were conducted in a circulating water channel(CWC), and a hot-film was used to measure the turbulence in wake cross-section at the distance range of 0.0~2.0L from the model. The hot film anemometer measured turbulent velocity fluctuations, and the timeaveraged mean velocity and turbulent intensity are obtained from the acquired time-series data. Measured results show well the general characteristics of turbulent intensity, kinetic energy and mean velocity distribution. Also, experimental equations are derived. These experimental equations show well the general characteristics of the turbulent wake behind the submerged body with simple configuration.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.3
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• pp.364-371
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• 2011

This paper presents experimental results and derived experimental equations to investigate the turbulent wake characteristics generated by the self-propelled SUBOFF submarine model. A self-propelled SUBOFF model which was assumed as an axial-symmetric body was used to create wake, and a thin strut was mounted on the topside of the model. The experiments were conducted in a circulating water channel(CWC), and the hot-film was used to measure the turbulence in wake cross-section at the distance range of 0.0~2.0L from the model. The hot film anemometer measured turbulent velocity fluctuations, and the time-averaged mean velocity and turbulent intensity are obtained from the acquired time-series data. Measured results show well the general characteristics of turbulent intensity, kinetic energy and mean velocity distribution. Also, this paper presents derived experimental equations, which is extended result to the reference [1]. These experimental equations show well the general characteristics of the turbulent wake behind the self-propelled submerged body.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.803-811
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• 2024

Nuclear accidents such as Fukushima Daiichi have highlighted the potential of passive safety systems to replace or complement active safety systems as part of the overall prevention and/or mitigation strategies. In addition, passive systems are key features of Small Modular Reactors (SMRs), for which they are becoming almost unavoidable and are part of the basic design of many reactors available in today's nuclear market. Nevertheless, their potential to significantly increase the safety of nuclear power plants still needs to be strengthened, in particular the ability of computer codes to determine their performance and reliability in industrial applications and support the safety demonstration. The PASTELS project (September 2020-February 2024), funded by the European Commission "Euratom H2020" programme, is devoted to the study of passive systems relying on natural circulation. The project focuses on two types, namely the SAfety COndenser (SACO) for the evacuation of the core residual power and the Containment Wall Condenser (CWC) for the reduction of heat and pressure in the containment vessel in case of accident. A specific design for each of these systems is being investigated in the project. Firstly, a straight vertical pool type of SACO has been implemented on the Framatome's PKL loop at Erlangen. It represents a tube bundle type heat exchanger that transfers heat from the secondary circuit to the water pool in which it is immersed by condensing the vapour generated in the steam generator. Secondly, the project relies on the CWC installed on the PASI test loop at LUT University in Finland. This facility reproduces the thermal-hydraulic behaviour of a Passive Containment Cooling System (PCCS) mainly composed of a CWC, a heat exchanger in the containment vessel connected to a water tank at atmospheric pressure outside the vessel which represents the ultimate heat sink. Several activities are carried out within the framework of the project. Different tests are conducted on these integral test facilities to produce new and relevant experimental data allowing to better characterize the physical behaviours and the performances of these systems for various thermo-hydraulic conditions. These test programmes are simulated by different codes acting at different scales, mainly system and CFD codes. New "system/CFD" coupling approaches are also considered to evaluate their potential to benefit both from the accuracy of CFD in regions where local 3D effects are dominant and system codes whose computational speed, robustness and general level of physical validation are particularly appreciated in industrial studies. In parallel, the project includes the study of single and two-phase natural circulation loops through a bibliographical study and the simulations of the PERSEO and HERO-2 experimental facilities. After a synthetic presentation of the project and its objectives, this article provides the reader with findings related to the physical analysis of the test results obtained on the PKL and PASI installations as well an overall evaluation of the capability of the different numerical tools to simulate passive systems.