• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.247-253
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• 2004

As a large scale port development in coastal waters proceeds step by step and populations in the vicinity of port are getting increased, the issue on "how to dispose the treated municipal water and wastewater in harbor" brings peoples′ concern. The submarine outfall system discharges the primary or secondary treated effluent at the coastline or in deep water, or between these two. The effluent, which has a density similar to that of fresh water, rises to the sea surface forming plume or jet, together with entraining the surrounding sea water and becomes very dilute. We intended in this paper to investigate the impact on dilution of effluent and the behavior of flume under the conditions of the seasonal and spatial temperature variations, which have not been noticeable in designing effective marine outfall system. To predict and analyze the behaviour and dilution characteristics of plume not just with the effluent temperature, but also with the seasonal variation of temperature of surround water and tidal changes, CORMIX(Cornell Mixing Zone Expert System)-GI have been applied. The results should be used with caution in evaluation the mixing zone characteristics of discharged water. We hope to help for the effective operation of outfall system, probable outfall design, protection of water quality, and warm water discharges from a power plant, etc.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.470-473
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• 2000

Because of the continuous growth of energy consumption, and also the tendency to site power lines and pipelines along the same routes, the close proximity of high voltage structures and metallic pipelines has become more and more frequent. Moreover, normal steady state and fault currents become higher as electric networks increase in size and power. Therefore, there has been and still is a growing concern (safety of people marking contact with pipeline, risk of damage to the pipeline coating, the metal and equipment connected to pipeline. especially cathodic protection system) about possible hazards resulting from the influence of high voltage power system on metallic structures(gas pipeline, oil pipeline and water pipeline etc.). Therefore, we analyze the interference problems when the gas pipeline is buried with power cable in the same submarine tunnel. This paper present the results of the study about interference mechanism, AC corrosion, limitation of safety voltage and analysis of indiction voltage.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.217-218
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• 2012

A load motor used for warship or submarine is with limited volume and weight, also specific environmental tests like impact, vibration, noise, temperature and EMC/EMI have to be satisfied. Induction motors, synchronous motors, BLDC motor and etc, are used depending on the purpose of using military equipment. Induction Motors are used for a number of military equipment more commonly due to the robust structure and simple maintenance. Domestic and foreign warships have a wide range of voltages as the DC voltage sources with battery are mainly used for them. The ${\Delta}-connection$ operation of the induction motor is required to make the maximum power in a low voltage level. But the elements' temperature of the inverter increases due to high input current when it is in the ${\Delta}-connection$ operation. Therefore, the induction motor must be driven with the Y-connection. The lack of voltage needs to be with the field weakening control. This paper suggests the optimum field weakening control algorithm to drive the induction motor with maximum power in a limited thermal and DC voltage condition.

• Proceedings of the KIEE Conference
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• summer
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• pp.597-601
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• 2004

HVDC(High Voltage Direct Current) is an underwater cable between Jeju Island and Haenam in main land and supplies approximately $50\%$ of electrical usage in Jeju Island. If there is any power failure due to HVDC, it will cost approximately 50,000 US dollars per day including Thermal Electrical Generation. Therefore it is absolutely necessary to recover the problem in rapid timely basis. Present survey method in Korea is done by scuba diver with air cylinder resulting very poor visual inspection. Other option is by only visual camera attached on miniature ROV for solely suey Purpose. This method does not includeburial depth of cable, cable position, cable condition & etc??‥‥.??? In result, current method does not generate any scientific or sophisticated data which does not allow any intelligent management decision. In conclusion, new method and new systems are needed urgently to upgrade current HVDC underwater cable survey technique in Korea to minimize the cost and time factors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.92-92
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• 2010

In this paper, the test is performed on MgO, which is used as a filler in epoxy additives, respectively (0, 1.0, 3.0, 5.0, 7.0, 10 [wt%]) for HVDC(high voltage direct current) submarine cable insulating material to improve electrical properties of epoxy resin in high temperature. The breakdown strength due to increasing amount of filler increased to 5.0 [wt%] by the effects of the Coulomb blockade. However, it is confirmed that strength of dielectric breakdown decreased because the filler functioned as impurities and affected the breakdown when filler additive exceeded by 5.0 [wt%] or more. We have found that the highest dielectric breakdown strength of specimen added 5.0 wt% at $25^{\circ}C$, and is more increased approximately 13.7 [%] than virgin specimen.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.48-48
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• 2010

In this paper, we have investigated temperature dependence of dielectric breakdown voltage at epoxy with added nano-filler(MgO), which is used as a filler of epoxy additives for HVDC(high voltage direct current) submarine cable insulating material with high thermal conductivity and restraining tree to improve electrical properties of epoxy resin in high temperature region. In order to find dispersion of the specimen, the cross sectional area of nano-composite material is observed by using the SEM(Scanning Electron Microscope) and it is conformed that each specimen is evenly distributed without the cohesion. As a result, it is confirmed that the strength of breakdown of all specimen at 50 [$^{\circ}C$] decreased more than that of the dielectric breakdown strength at room temperature. When temperature increases from 50 [$^{\circ}C$] to 100 [$^{\circ}C$], we have confirmed that breakdown strength of virgin specimen decreases, but specimens with added MgO show constant dielectric breakdown strength.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.7
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• pp.536-542
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• 2016

To enhance tracking efficiency, a target-tracking filter with a resource management algorithm is required. One of the resource management algorithms chooses or evaluates the proper sampling time using cost functions which are related to the target tracking filter. We propose a resource management algorithm for bearing only tracking environments. Since the tracking performance depends on the system observability, the bearing-only tracking is one of challenging target-tracking fields. The proposed algorithm provides the adaptive sampling time using the variation rate of the error covariance matrix from the target-tracking filter. The simulation verifies the efficiency performance of the proposed algorithm.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.4
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• pp.517-524
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• 2010

This paper covers the numerical studies performed to investigate the characteristics of turbulent wake generated by a submarine, SUBOFF model. A SUBOFF model assumed as an axial-symmetric body was used to generate wake. The numerical simulation was performed by using a commercial S/W, FLUENT, with the same condition as the experiments by Shin et al.(2009). Mainly the cross-sectional distribution of the time-averaged mean wake and turbulent kinetic energy was compared with the experiments. Both results are agreed well with each other in the propeller wake section, but the agreement between both is not so satisfied in the far wake field. It means that more numerous number of grid points and their concentration should be required in that field.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1997.11a
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• pp.97-142
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• 1997

The Seoguipo Formation occurs only in a small exposure along the coast of the Seoguipo City, but in the subsurface, underlies tile western part of the Bugcheon-Pyoseon Line in the northeastern part of tile island. The Bugcheon-Pyoseon Line is presumed to be a facies boundary that reflects tile distribution of hyaloclastites resulted from submarine volcanic activity. The Seoguipo Formation is distributed in the subsurface along the part which is lower than 400m in average altitude, and occurs at El. -5.76∼-46.63m in tile southern area, El. -41.89∼-57.97m in the western area, El. -13.15∼-50.59m in the northern area. Therefore, the southern area was uplifted after the deposition of the Seoguipo Formation. In the subsurface, the vertical depth of the volcanic rocks of the Cheju Volcanic Edifice is El. -40.6m in the southern area, El. -111.3m in the western area, El. -81.5m in the northern area and El. -134.7m in the eastern area. The unconsolidated U Formation, which is, overlying the basement and about 70∼250m thickness underlies the whole island. There is a positive correlation between tile groundwater level and the depth of the subsurface distribution of the Seoguipo Formation. Consequently, it is conformed that the subsurface distribution of the Seoguipo Formation plays important role for controlling the characteristics of the reservoir of tile groundwater in Cheju Island.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.4 s.310
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• pp.60-66
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• 2006

Underwater ultrasonic communication is critical to explore and development ocean using instrument. Essential to these applications is the reliable teleoperation and telemetering of the unit. But the problem is that the controllability of the instrument and the reliability of submarine communication are decreased, as so various passive noises are generated. In the existing methods, the control informations, received from an observation instrument, are identified used by hardware and repeatedly compared with standard information. However, such a method weakens the efficiency in controllability-centered systems. This study presents an ultrasonic signal detection algorithm that can identify the ultrasonic signal without the influence of disturbances due to underwater environmental changes. Likewise, the logicality of detection algorithm were ascertained by simulation.