• Journal of the Society of Naval Architects of Korea
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• v.42 no.1 s.139
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• pp.18-23
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• 2005

The transmission and reflection coefficiencies of a BBDB-type floating breakwater in water of finite depth are studied taking account of fluctuating air pressure in the air chamber. The wave potential is calculated by a hybrid integral equation consisting of a Green integral equations associated with the Rankiue Green function inside the BBDB and the Kelvin Green function outside. The transmission and reflection coefficients of the breakwater are obtained directly from the potential solution in the outer region.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.9
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• pp.656-661
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• 2013

In this study, the moisture content, charge discharge current, electrostatic capacity and dielectric loss tangent are measured for the specimen of bisphenol type epoxy resin which is mixed with squared amorphous silica filler and dipped in hot water of $50^{\circ}C$ for 169 days. The results of this study are listed below. The longer of deposition day, the charge and discharge current was increased. It is considered that the reason is because there was water attack through the squared silica surface. The longer of deposition day, the absorption rate of all specimens was increased. It found that the absorption rate reached saturated state after 100 days. The higher frequency and the longer of deposition day, the $tan{\delta}$ was decreased. Also, It found that the $tan{\delta}$ and electrostatic capacity of the specimen which is mixed with squared filler are greater.

• Membrane and Water Treatment
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• v.5 no.4
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• pp.265-279
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• 2014

Pervaporation is the most promising technique for the recovery of ethanol from the fermentation system. To date, extensive research has been conducted on the exploration of membrane materials with favorable properties. In this paper, we primarily review the performance of adsorbent-filled rubbery membranes. In addition, the fundamental mechanisms of ethanol and water molecules transportation through composite membranes are demonstrated, particularly from the perspective of cluster formation. Finally, future prospects are also analyzed to develop the guidelines for the future development of excellent membrane materials for ethanol concentration. This paper is not meant to be an exhaustive overview, rather a specialized summary that allows readers to select the information appropriated to their topics.

• Water for future
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• v.13 no.4
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• pp.33-40
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• 1980

It has been very difficult to analyse, clearly, the mechanism of the suspended sediment that changes, largely, the coastline, on-shore and off-shore. It is due to not only the complexity of the factors in nature but the measurement technique of suspended sediment characteristics both in nature and loboratory. The purpose of this paper are to obtain the time-rate of change in the concentration of suspended sediment, the vertical distribution of it and the effect of the fall velocity of its particle, and to make clear the mechanism of sand transportation in suspension, analysing the diffusion equation, by the computer, due to the small amplitude wave theory.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1271-1275
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• 2004

The purpose of this study is to present a standardized scheme for providing agriculture-related information at various spatial resolutions of satellite images including Landsat +ETM, KOMPSAT-1 EOC, ASTER VNIR, and IKONOS panchromatic and multi-spectral images. The satellite images were interpreted especially for identifying agricultural areas, crop types, agricultural facilities and structures. The results were compared with the land cover/land use classification system suggested by Ministry of Construction & Transportation based on NGIS (National Geographic Information System) and Ministry of Environment based on satellite remote sensing data. As a result, high-resolution agricultural land cover map from IKONOS imageries was made out. The results by IKONOS image will be provided to KOMPSAT-2 project for agricultural application.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.2
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• pp.94-102
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• 2015

A hydroscopic polymer is used as the adsorbent in an adsorption refrigeration system. A pair of plate-type heat exchangers, thinly coated with the polymer, is simulated using a two-dimensional transient model to predict performance of the system. It is predicted that the system would yield 0.57 kW SCP and 0.47 COP at $80^{\circ}C$ heating and $30^{\circ}C$ cooling temperatures. In comparison with a conventional silica gel-water system, the COP is comparable but SCP is about three times larger. The slow mass diffusion rate of the polymer should be improved for better performance.

• Journal of Ocean Engineering and Technology
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• v.20 no.4 s.71
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• pp.64-69
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• 2006

A numerical analysis is made to investigate the wave absorption efficiency of a OWC-type wave power generator. Energy absorption by an OWC(Oscillating Water Column) air-chamber is computed in regular waves, taking account of the oscillating surface-pressure, due to pressure drop, across the duct of the air chamber. The problem is formulated in the scope of potential theory and solved by the Localized Finite Element Method(LFEM), based on the classical variational principle. The efficiency of energy absorption is investigated by. changing wave conditions, sea-bottom slope and pressure drop coefficient.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.8
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• pp.674-682
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• 2003

Natural gas hydrate typically contains 85 wt.% water and 15 wt.% natural gas, and commonly belongs to cubic structure I and II. Also, 1m$^3$ hydrate of natural gas can be decomposed to 200 m$^3$ natural gas at standard condition. If this characteristic of hydrate is reversely utilized, natural gas is fixed into water and produced to hydrate. Therefore the hydrate is great as a means to transport and store natural gas. So, the tests were performed on the formation of natural gas hydrate is governed by the pressure, temperature, gas composition etc. The results show that the equilibrium pressure of structure II is approximately 65% lower and the solubility is about 3 times higher than structure I. Also if the subcoolings of structure I and structure II are more than 9 K and 11 K respectively, the hydrates are rapidly formed.

• Nuclear Engineering and Technology
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• v.50 no.7
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• pp.1024-1036
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• 2018

In this paper, McCARD code was verified using various models listed in the NUREG/CR-6361 benchmark guide, which provides specifications for single pin-cells, single assemblies, and the whole core classified depending on the nuclear properties and structural characteristics. McCARD code was verified by comparing its results with those of SCALE code for single pin-cell and single assembly benchmark problems. The difference in the multiplication factor obtained through the two codes did not exceed 90 pcm. The benchmark guide treats a total of 173 whole core experiments. The experiments are categorized as simple lattices, separator plates, reflecting walls, reflecting walls and separator plates, burnable absorber fuel rods, water holes, poison rods, and borated moderator. As a result of numerical simulation using McCARD, the mean value of the multiplication factors is 1.00223 and the standard deviation of the multiplication factors is 285 pcm. The difference between the multiplication factors and the experimental value is in the range of -665 pcm to + 1609 pcm. In addition, statistics of results for experiments categorized by reactor shape, additional structure, burnable poison, etc., are detailed in the main text.

• New & Renewable Energy
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• v.8 no.2
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• pp.24-32
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• 2012

Natural gas hydrates have a high potential as the 21st century new energy resource, because it have a large amount of deposits in many deep-water and permafrost regions of the world widely. Natural gas hydrate is formed by physical binding between water molecule and gas mainly composed of methane, which is captured in the cavities of water molecules under the specific temperature and pressure. $1m^3$ methane hydrate can be decomposed to the methane gas of $172m^3$ and water of $0.8m^3$ at standard condition. Therefore, there are a lot of practical applications such as separation processes, natural gas storage transportation and carbon dioxide sequestration. For the industrial utilization of methane hydrate, it is very important to rapidly manufacture hydrate. However, when methane hydrate is artificially formed, its reaction time may be too long and the gas consumption in water becomes relatively low, because the reaction rate between water and gas is low. So in this study, hydrate formation was experimented by adding natural zeolite and Synthetic zeolite 5A in distilled water, respectively. The results show that when the Synthetic zeolite 5A of 0.01 wt% was, the amount of gas consumed during the formation of methane hydrate was higher than that in the natural zeolite. Also, the natural zeolite and Synthetic zeolite 5A decreased the hydrate formation time to a greater extent than the distilled water at the same subcooling temperature.