• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.10a
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• pp.291-293
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• 2012

AMD 능동형 제진장치를 이용하여 플로팅 구조물을 제어하기 위해서는 수조실험을 통해 플로팅 함체 구조물의 롤링방향에 대한 동적 특성을 추정한 후 대상 구조물 특성에 적합한 제어알고리즘을 적용하여 수치시뮬레이션을 통한 제어의 가능성 확인 및 향후 실제 제진장치를 설치하여 검증실험을 통해 플로팅 구조물 능동제어의 효과를 검증해야 한다.

• Water for future
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• v.29 no.1
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• pp.213-220
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• 1996

This paper presents an experimental study on the discharge head of Cherepnov water lifter that was continuously operated with the aid of the siphon. The energy used by the Cherepnov water lifter is derived from the potential energy ofthe water itself. The lifter consists of three interconnected tanks and five pipes, one of which is open and two others are hermetically sealed. The effects of varying operating parameters such as the tank and pipe size, the ratio between head of discharge and drop height were analyzed. As a result, factors that can maximize the efficiency and increase the average delivery rate were indentified. When the ratio between head of discharge and drop height is about 0.5, the efficiency of Cherepnov water lifter is maximized. In order to design the efficient Cherepnov water lifter, the discharge head of the Cherepnov water lifter should be assigned to be twice as much as the drop height. The effect of tank size on the efficiency is less than 5%, while the effect of the pipe size is not negligible. The larger the pipe size is, the more the efficiency increases.

• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.3
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• pp.1-8
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• 1989

The flow characteristics of a circulating water channel which is appropriate for a flow measurement and visualization in the laboratory has been investigated by using a Laser Doppler Anemometer. In order to get a stable and uniform distribution of mean velocity at the test section, the surface flow accelerator is designed and used. The experimental results that the turbulent structure should be considered with the mean velocity for obtaining the reasonable uniformity at the test section.

• Journal of Energy Engineering
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• v.8 no.2
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• pp.298-308
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• 1999

Experimental study on characteristics of direct contact condensation of steam discharged into a sub-cooled water pool has been performed using five different sizes of horizontal nozzle over a wide range of steam mass fluxes and pool temperatures. Steam condensation phenomena have been observed visually and by taking pictures of steam jets using a high speed video camera. Two different steam jet shapes such as ellipsoidal shape and conical shape were typically observed for a stable steam jet, depending on the steam mass flux and pool temperature. The steam jet expansion ratio and the steam jet length as well as the condensation heat transfer coefficients were determined. The effect of steam mass flux, pool temperature, and nozzle diameter on these parameters were also discussed. Empirical correlations for the steam jet lengths and the condensation heat transfer coefficients as a function of steam mass flux and condensation driving potential were established. The axial and radial temperature distributions in steam jet and in surrounding water were measured. The effect of steam mass flux, pool temperature, and nozzle diameter were also discussed. The condensation regime map, which consists of six regimes such as chugging, transient chugging, condensation oscillation, stable condensation, bubble condensation oscillation, and intermittent oscillation condensation, were established. In addition, the dynamic pressures at the pool wall were measured. The close relation of dynamic pressure and steam condensation mode, which is also dependent on steam mass flux and pool temperature, was found.

• Journal of Navigation and Port Research
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• v.37 no.3
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• pp.269-273
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• 2013

Underwater acoustic channels are generally recognized as one of the most difficult communication media because of the multipath propagation, dispersion, and so on. MIMO (Multiple-input multiple-output) techniques have been actively pursued in underwater acoustic communications recently to increase the data rate over the bandwidth-limited channels. The transmit diversity techniques can be applied in this case, and one of them is Alamouti's scheme. In this paper the performances of the transmit diversity technique are evaluated via experiment. Two transmitters and two receivers were used in experiment, and the experiment was performed in indoor water tank. The error rate 5~8% was confirmed in experimental results, and these are the improved values than the error rate 14.8% for SISO(Single-input single-output) channel under same data rate condition.

• Journal of the Korean Society for Marine Environment & Energy
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• v.2 no.1
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• pp.40-48
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• 1999

Wave absorbing system is needed at various kinds of wave basins (wave flume, towing tank, square tank) for the model test related to the ocean engineering. In this paper, the performance of wave absorbing system with new concept is estimated throughout the experiments. Herein, the wave absorbing system is designed by punching plate with a given porosity which is installed horizontally and submerged near the water surface. As the incident wave generated by a wave maker advances above a punching plate, the strong jet flow is formed near a hole of punching plate. As a result, wave energy is dissipated into heat energy, Systematic model tests were conducted at KRISO to verify the performance of the wave absorber using a punching plate. It was found that the reflection coefficient of wave absorber is deeply dependent on both the porosity and the submerged depth of a punching plate. Inclined installation of a punching plate shows better performance than a horizontal one within a certain inclined angle.

• The Journal of the Acoustical Society of Korea
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• v.23 no.5
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• pp.362-369
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• 2004

The High-frequency (30 ∼ 120 ㎑) bottom reflection loss at rough water-sediment interface is affected by the gram size distribution of the sediments. The roughness of the bottom surface is represented by "acoustical roughness. g/sub R/" The grain size of sandy sediments is g/sub R/∼O(1) and the dependence as a function of frequency. We suggest the modified bottom reflection loss model (HYBRL model , HanYang university Bottom Reflection Loss model) that include in the deviation of the reflection loss as a function of the grain size distribution and frequency dependence. And bottom reflection loss model of frequency dependence and deviation of bottom properties is verified by water tank and field experiments.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.5
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• pp.257-264
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• 2016

In this study, experiments for measurements of entrainment rate of fluid mud were carried out using annular flume domestically for the first time. Six entrainment tests using kaolinite sediments were conducted with different initial concentrations of fluid mud. It is shown that sediment settling counteracts the otherwise buoyancy dependent entrainment of fluid mud, and that the settling effect leads to a measurably decreased entrainment rate at higher Richardson numbers in comparison with entrainment of salt water, due to additional dissipation of turbulent kinetic energy in the interfacial layer. Through the comparison with previous other studies, the overall performance of the annular flume, the experimental procedure and the test results in simulating the entrainment of fluid mud are shown to be good enough to verify.

• 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 KIEE Conference
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• 2006.10c
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• pp.105-107
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• 2006

유출지하수나 지료수를 열원으로 하는 지열히트펌프의 기초자료로 활용하기 위하여 Pond Loop형 열교환기를 설계, 제작하여 유동이 없는 수조 내에서 수조의 온도가 변화함에 따라 일정한 열교환기 입구온도를 유지하면서 열전달량을 측정하였다. 그 결과 수조를 Heat Source로 사용하는 경우 5,500${\sim}$4,500 kcal/h의 열량이 전달되었고, 수조를 Heat Sink로 사용할 경우 5,200${\sim}$3,500 kcal/h의 열량이 전달되었다. 또한 열교환기 관내 유속이 증가함에 따라 열전달량이 증가하는 경향성을 확인할 수 있었고, 이는 동시에 열교환기 입출구의 차압을 증가시킴을 알 수 있었다. 열교환기의 설계단계애서 사용하였던 열전달관계식으로 구한 총괄열전달계수, U와 실험값을 통해 유추한 U값을 비교 한 결과 실험에 의해 유추된 U값이 24${\sim}$27% 설계치 보다 크게 나타났다. 본 연구를 통하여 유출지하수 뿐만 아니라 하수 및 하천수를 이용한 지열히트펌프의 기초자료를 확보할 수 있었다.