• Journal of Advanced Marine Engineering and Technology
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• v.28 no.8
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• pp.1313-1323
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• 2004

In accordance with adoption of new convention for the control of ship's ballast water at the diplomatic conference held in London Feb, 2004, every country has to regulate the ballast water and deposit matters. When this Resolution comes into effect in 2009, all vessels engaged in international voyage must have ballast water control program, ballast water records, equipments which are suitable to the standard of exchange and performance for the ballast water. This study estimates objectively their performances, merits and demerits of the ballast water treatment technique and exchanging techniques for safe operation of ships. It is desirable to design an equipment to control the ballast water using the brush-type vacuum suction nonstop reverse cleaning system to overcome the clogging phenomenon and the direct disc filtering to maximize filtering area for the optimum process considering biological availabilities. It will be expected to protect against marine pollution and to maintain clean sea if it is secured to develop new ballast water treatment techniques. And it will also be expected to cope with the Resolution and each regulation of the developed countries from the ballast water.

• Fire Science and Engineering
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• v.30 no.4
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• pp.94-102
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• 2016

When establishing shielding facilities for EMP protection, WBC effect is used to protect fire pipes and honeycomb cells are inserted into the fire pipes to improve the shielding effectiveness. At this point, the smaller unit cell of honeycombs becomes, the more likely it interrupts the flow of water, which ends up clogging the fire pipes with sediment. To prevent this phenomenon, I would suggest a design method due to the pilarization loss of water molecules that contributes to increasing the size of honeycomb cells and remaining thin-walled sufficient for required shielding effectiveness.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1380-1384
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• 2006

Sediments deposited on lateral drain pipes in a tunnel make lateral porous pipes clogged. Since the safety of the tunnel can be affected by this phenomenon, it requires a regular maintenance of the lateral drain pipes. In this study, a series of centrifugal tests were conducted in order to find out the method which can reduce the clogging effect considerably. Four different types of tunnel drain configurations were selected in the experiments. By analysis of sediments for each configuration, the optimum drain configuration that can minimize sedimentation of cement constituents was investigated. As a results, the existing drain configuration which uses filter concrete appear to produce much sediments. In contrast, the new drain configuration appears to be able to reduce sedimentation ratio up to almost 50% comparing with the existing one. From these observations, it may be concluded that the new drain configuration, in which the lateral porous pipes of a tunnel are surrounded by gravel layer and non-woven geotextile, has high efficiency in maintenance.

• Journal of the Korean Geotechnical Society
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• v.34 no.11
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• pp.33-41
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• 2018

Soil internal erosion is a phenomenon in which fines attached to the solid skeleton are detached by fluid flow, and this continuous fine migration weakens the hydro-mechanical characteristics of the ground structure. This paper proposed governing equations for fine migration in pore spaces and its related scheme for the numerical analysis. Phase diagram for fine particles includes three different states: detached fines in the liquid phase ($c_e$), attached fines in the solid phase (${\sigma}_a$), and pore-clogged fines in the solid phase (${\sigma}_s$). Numerical formulations for finite element method are developed based on the hydraulic governing equations of pore fluid and fine migration. This study proposed a method of estimating model parameters for fine detachment, attachment, and clogging from 1D erosion experiments. And it proposed an analytical formula for hydraulic permeability function considering fine clogging. Numerical analysis of the previous erosion test developed the numerical scheme and verified the adequacy of fine migration models.

• Journal of the Korean GEO-environmental Society
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• v.13 no.9
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• pp.45-51
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• 2012

The calcium hydroxide$(Ca(OH)_2)$ which is the cement hydrate flowed into the tunnel by groundwater is reacted with microorganism in the soil, carbon dioxide$(CO_2)$ and the vehicle's exhaust gas$(SO_3)$. So its by-products are precipitated at the drainage pipe and these cause the drainage clogging. By this phenomenon, Degradation of water flow at the drainage system of the tunnel occurred and also pore water pressure is increased. Hence the acceleration of seepage and degradation of lining is occurred. The purpose of this study is to evaluate the field applicability of the Quantum Stick and Magnetic treatment in prevention of scale deposits at the Namsan ${\bigcirc}{\bigcirc}$ tunnel and the Zone ${\bigcirc}{\bigcirc}{\bigcirc}$ of subway. These technologies were installed into drainpipes with their performance monitored through occasional site visits. SEM and XRD were also performed on scale collected from these drainpipes. As a result, in case which factor technology is applied, scale creation is remarkably decreased and especially Quantum Stick treatment performing better than Magnetic treatment. Therefore, additional application of Quantum Stick or Magnetic treatment to the existing drainage is expected to decrease the drainage clogging of the drainage.

• Journal of the Korean GEO-environmental Society
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• v.14 no.2
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• pp.13-17
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• 2013

Clogging phenomenon in drainage system is one of the important problems and this phenomenon would be bad effect to structure of tunnel, so it needs a remedy urgently. Recently, scale in drainage pipe is removed by water jet cleaning and other treatment. But these treatments need much cost and regular management. In this study, magnetic device was used to solve this problem and an effect of prohibiting scale in accordance with array of magnetic device was investigated. Analysis method was visual analysis and measuring weight of each pipes. As a result, interior top and out-bottom (CASE II) was the most effective array to prohibit scale. and interior left and right (CASE III), interior top and bottom (CASE I) was effective for prohibiting scale in order.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.12
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• pp.74-81
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• 2011

A computational approach was developed to understand about the arc quenching process in a gas circuit breaker(GCB). This approach is a program to analyze the gas flow in the breaker. The arc is processed at the same time. The program was used the so-called FLIC method for gas analysis techniques. It was referenced that the arc is interpreted the 'a Simplified Enthalpy Flow Arc Model'. In order to validate about the results of the program, a Auto Puffer GCB was chosen as the test subject. Because, the breaker is the one that arc current is interrupted by using the arc heating. And also, the current interrupting capability can be obtained only owing to the positive utilization(auto puffer) of the clogging phenomenon, without other puffer actions. In this paper, it has been realized that the entire arc quenching process is computerized, which is based on the self-flow current interruption by the auto puffer action. This program, which was verified through experiments, produced good results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.230-236
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• 2020

A trash screen is installed in front of the inflow channel of a drainage pumping station, sewage treatment plant, and a power plant to block floating contaminants. The bottleneck phenomenon, which decreases the water inflow, causes damage to the damper as a result of clogging in between the screen if string type obstacles are not removed. In this paper, the apron was removed, and the screen was expanded, to prevent breakage of the bottleneck phenomenon and string type obstacles. This was designed using an extended rake by adding an inner rake in between the screen interspace to remove the bottleneck phenomenon and string type obstacles. To design the inner rake that satisfies the allowable stresses of the existing damper rake, the experiment points were determined according to the experimental design method using the inner rake vertical length and the thickness of the reinforced section as parameters. The use of the ANSYS static structural module and statistical analysis tool R software gives the optimized shape according to the response surface method. The relative error between the response surface analysis results and the simulation results was 1.63% of the determined optimal design-point rake length of 210.2 mm and the reinforcement section thickness of 2 mm. Through empirical experiments, a test rake was constructed to the actual size, and approximately 97% of the bottleneck phenomenon and string type obstacles could be removed.

• Journal of Mechanical Science and Technology
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• v.18 no.9
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• pp.1680-1688
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• 2004

The information indicating device plays an important part in the information times. Recently, the classical CRT (Cathod Ray Tube) display is getting transferred to the LCD (Liquid Crystal Display) one which is a kind of the FPDs (Flat Panel Displays). The OLED (Organic Light Emitting Diodes) display of the FPDs has many advantages for the low power consumption, the luminescence in itself, the light weight, the thin thickness, the wide view angle, the fast response and so on as compared with the LCD one. The OLED has lately attracted considerable attention as the next generation device for the information indicators. And also it has already been applied for the outside panel of a mobile phone, and its demand will be gradually increased in the various fields. It is manufactured by the vapor deposition method in the vacuum state, and the uniformity of thin film on the substrate depends on the temperature distribution in the point-cell source. This paper describes the basic concepts that are obtained to design the point-cell source using the computational temperature analysis. The grids are generated using the module of AUTOHEXA in the ICEM CFD program and the temperature distributions are numerically obtained using the STAR-CD program. The temperature profiles are calculated for four cases, i.e., the charge rate for the source in the crucible, the ratio of diameter to height of the crucible, the ratio of interval to height of the heating bands, and the geometry modification for the basic crucible. As a result, the blowout phenomenon can be shown when the charge rate for the source increases. The temperature variation in the radial direction is decreased as the ratio of diameter to height is decreased and it is suggested that the thin film thickness can be uniformed. In case of using one heating band, the blowout can be shown as the higher temperature distribution in the center part of the source, and the clogging can appear in the top end of the crucible in the lower temperature. The phenomena of both the blowout and the clogging in the modified crucible with the nozzle-diffuser can be prevented because the temperature in the upper part of the crucible is higher than that of other parts and the temperature variation in the radial direction becomes small.

• Journal of Soil and Groundwater Environment
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• v.19 no.5
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• pp.26-34
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• 2014

A $1.5m(L){\times}1.0m(W){\times}1.1m(H)$ polypropylene (PP) field scale electroniketic system coupled with stainless steel electrodes was designed to examined metal removal performance applied 0.2-0.35 V/cm potential gradient and 0.05-0.5M lactic acid for 20 day. Electroosmosis permeabilities of $2.2{\times}10^{-5}cm^2/V-s$ to $4.8{\times}10^{-5}cm^2/V-s$ were observed and it increased with the potential gradient increased. The reservoir pH controlled at $7.0{\pm}1.0$ has been effectively diminished the clogging of most metal oxides. The best removal efficiency of Zn, Pb, and Ni was 78.4%, 84.3%, and 40.1%, respectively, in the field scale EK system applied 0.35 V/cm and 0.05M lactic acid for 20 days. Increasing potential gradient would more effectively enhance metal removal than increasing concentration of processing fluid. The reservoir and soil temperatures were majorly related to potential gradient and power consumptio. A $4-16^{\circ}C$ above room temperature was observed in the investigated system. It was found that the temperature increase in soil transported the pore water and metals from bottom to the topsoil. This vertical transport phenomenon is critical for the electrokinetic process to remediate in-situ deep pollution.