• Journal of Ocean Engineering and Technology
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• v.32 no.5
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• pp.351-360
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• 2018

The construction of large scale harbor structures at Maengbang beach, which is located on the eastern coast of Korea, is of great concern because it may cause disastrous beach erosion in the vicinity. Therefore, a hydraulic model experiment was conducted to examine the morphological changes after such construction. The water depth was scaled using the method of Van Rijn (2010), which is a well-known scale law, but the results appeared to be overestimated. The present study developed a new scale law that applies an equilibrium beach profile formula to scale the model evolution to the prototype scale. When compared with survey data observed at Maengbang beach, the proposed method showed better agreement than the method of Van Rijn (2010).

• Journal of the Korean Society of Safety
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• v.17 no.4
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• pp.25-30
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• 2002

This paper demonstrates the effects of dust electrical resistivity on electrostatic precipitability. The effects of gas temperature, velocity and humidity on the collection efficency were considered by used of coal fly ashes from fluidized bed combustion boiler. The experiments for collection efficiency were carried out in the pilot plant. The ashes which have non-spherical geometry and high electrical resistivity were used. Electrical resistivity is an important property for the collection efficiency in the electrostatic precipitators. Fly ash resistivity as a function of temperature up $350{\circ}C$ and water concentration(up to 15%) has been experimentally investigated using the resistivity test equipment consisted of the movable electrode, dust cup, and furnace. As the resistivity of fly ash in the operating temperature($150{\circ}C$) of an electrostatic precipitator was measured higher than $1010{\Omega}{\cdot}$cm, flue gas conditioning in the electrostatic precipitator to reduce the resistivity of fly ash is required.

• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.42-47
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• 2014

This paper is aimed to investigate and analyze of characteristic for electrical equipment and work environment for the small-scale site. In order to investigate and analyze electrical equipment and work environment for preventing electric shock disaster in construction sites, 50 small-scale construction sites and 12 large-scale construction sites are selected. This paper completed site investigations of low-voltage equipment and the portable electric machine and equipment in 12 large-scale construction sites and 50 small-scale construction sites. The findings were about the electric shock environment relevant to the ground-relevant equipment, the panel board, the protection tools, the sockets, the temporary wiring system, the portable and movable electric machines and equipments in small-scale construction sites. Finally, this study analyzed the domestic and foreign relevant standards and regulations and these findings can be utilized as educational data warning electric shock risk caused by electric equipment in small-scale construction site.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.10a
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• pp.3-10
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• 2006

Recently it is coming to be hish reality on visual system in ship-handling simulator depending on the technical development of 3D computer graphics. Even with high reality, it is possible that visual information presented seafarers through screen or display is not equivalent to the real world. In docking maneuvering, visual targets or obstructs are sighted close to ship's operator or within few hundred meters, so it might be possible to affect visual information such as the difference between both eyes' and single eye's visual sight. Because it is not possible to perceive of very slow ship's movement by visual in case of very large vessels, so the Doppler Docking SONAR and/or Docking Speed and Distance Measurement Equipment were developed and applied for safety docking maneuvering. By the way, the simulator training includes the ship's maneuvering training in docking, but in Ship-handling Simulator and also onboard, there are some limitations of perception of ship's movement with visual information. In this paper, perception of ship's movement with visual system in Ship-handling Simulator and competition of performances of visual systems that are conventional screen type with Fixed Eye-point system and Mission Simulator. We got some conclusions not only on the effectiveness for visual system but also on the human behavior in docking maneuver.

• Electrical & Electronic Materials
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• v.7 no.3
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• pp.187-199
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• 1994

In order to find an effect of structural changes due to variation of addition ratio of anhydride hardener and postcuring herat-treatments upon electrical properties of epoxy composites, the dielectric properties over a frequency range from 30[Hz] to l[MHz] were investigated in the temperature range of 20-180[.deg. C]. From the dielectric properties, the a peaks related with glass-transition phenomena of epoxy network appeared near 130[.deg. C], the conduction loss in high temperature region above 150[.deg. C] due to thermal dissociation of hardener started off with the low frequency side and the .betha. peak concerned with contribution of movable unreacted terminal epoxy groups and curing agents in the glass states concurred with the high-frequency side below 20[.deg. C]. And an effect of an hydride hardener upon structural changes and of postcuring heat treatments upon structural stability in epoxy composites would be explained through the estimation of the distribution of relaxation times and the activation energy for a .alpha. peak according to the WLF equations.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3271-3273
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• 1999

In this paper, new micromachined tunable bandpass filters for multi-band millimeter-wave telecommunication systems are proposed. Two types of mm-wave tunable filters are fabricated using micromachining technology and the responses of the filters are measured. One is two-pole lumped elements filter and the other two-pole resonators filter. Frequency tunability of the filter is achieved by changing the gap between a common CPW ground plate and the movable cantilever beam connected to the transmission line with the controllable range of 2.5 ${\mu}m$. The deflection of cantilever beam is measured with the applied DC voltage. With the applied bias voltage from 0 to 50 V, the fabricated filters show 0.6 GHz(2.3 %) at 26.6 GHz, and 0.8 GHz(2.5%) at 32 GHz center frequency shift for the lumped elements and resonators filter, respectively.

• Korean Institute of Interior Design Journal
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• v.18 no.6
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• pp.194-201
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• 2009

The purpose of this study is to develop basic data for the efficient space plan of the Department Store focusing on users by survey of preference to methods of plan considering the functional phase, the economical phase and the adaptable phase. The results are as follows : First, we could know that users had the low degree of satisfaction to the adaptable phase of space plan for Supporting Facilities in department stores at the present time. Second, we must have the appropriate space size by using structure, doors and windows for user's satisfaction. This is the method of plan considering the functional phase for Supporting Facilities. And we could think that the methods of using the center flow plan and the arrangement of two or three facing are good for user's satisfaction. Third, it will be efficient plan if we find methods to be cleaned the structure easily and to be changed and repaired the system furniture easily for management. that methods are to be considered the economical phase for Supporting Facilities. Forth, methods of plan considering the adaptable phase are to change the size of space by using the movable type furniture and the form of space by changing structure.

• International Journal of Safety
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• v.8 no.2
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• pp.9-14
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• 2009

This paper describes analysis of risk voltage for grounding electrode where earth leakage current is injected. To assess risk voltage of grounding electrode, the grounding simulator and CDEGS program were used to obtain measured data and theoretical results of this study. The grounding simulator was composed of a hemispherical water tank, AC power supply, a movable potentiometer, and test grounding electrodes. The shapes of grounding electrode model was ground rod. The potential rise was measured by grounding simulator, and the touch and step voltages were computed by CDEGS program. As a consequence, the potential rise of ground rod abruptly decreases with increasing the distance from the grounding electrode to the point to be tested. The touch voltage above the ground rod was low, but the step voltage was high. The measured results were compared with the computer calculated data and were known in good agreement.

• The Transactions of the Korea Information Processing Society
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• v.7 no.11S
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• pp.3675-3683
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• 2000

The Handoff is the core technical factor that is required when mobile host moves from one area to another, while transmitting and receiving data. The existing works try to minimize the loss of pockets by forwarding packets to the Cell which a mobile host will move to. However, though the loss quantity is little, the accumulated loss can del(rade the performance of the TCP, and can be a serious problem if data is sensitive to the loss of packets. In this paper, we can reduce a memory requesting in FA by restricting the mobile host to move within at most 2 movable cells and design the improved handoff protocol for Mil to receive packets seamlessly in spite of handoff. We can evaluate that the suggested method is superior to the previous method, as a result of comparing with it.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2128-2135
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• 2009

In this paper, current limiter using a magnetic switching which is based on magnetic flux change in the case of fault is proposed. This current limiter consists of iron-core and three parts of coils. One is the primary coil connected to the power system. Another is the secondary coil wound to the opposite direction of the primary coil's winding. The other is the secondary of the secondary coil which is a movable copper plate winding and located below the secondary coil. In the normal state, the magnetic flux produced in the primary and secondary coils flows to the opposite directions each other and becomes to be canceled out. Therefore the voltages induced between the coils are zero. In the case of a fault, at the moment of a fault occurrence recognition, the switch connected to a secondary coil is opened and the secondary of the secondary coil is pulled out to the outside of the iron-core. Then, magnetic flux becomes to flow through the iron-core. Accordingly, the voltage is induced between the both ends of the primary coil and makes the current reduced. Therefore it is possible to cut off the circuit breaker easily with the proposed current limiter. This paper analyzes the current limiting effects and the detailed results are given.