• Journal of the Korean Society of Marine Environment & Safety
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• v.6 no.2
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• pp.47-56
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• 2000

This paper describes a simple prediction method of beach recession induced by storm surge. In order to evaluate the severest beach erosion, it is assumed that maximum beach recession occurs at the coming of storm surge overlapped with spring tide. Consequently, total surge lev디 becomes the sum of storm surge level and tidal range. Generally, storm surge level around Korea is small compared with tidal range. Therefore total surge can be expressed as the series of surges, which have same duration as tide. Through the case studies, the author Investigates correlation between tidal range, duration, wave condition, beach slope and beach recession.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.8
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• pp.96-101
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• 2012

A surge protection device of the metal oxide varistor(MOV) has been commonly used for preventing electrical damage in many electronic equipments. The MOV has a property that leakage current is increased and might be permanently damaged when it is exposed continuously to the electrical stresses such as lightening surges. In this paper, we propose a novel surge protection circuit adopting a silicon controlled rectifier(SCR) in the traditional protection circuits using the MOV device simultaneously. When lightning surges are injected to the proposed circuit, the MOV lets the surge pulses bypassing through the ground at first up to the level that SCR begins to operate. Above the threshold level of turning on the SCR, the SCR operates bypasses large surge currents to the ground. Proposed circuit was verified with a leakage current experiment and PSpice circuit simulations under the repeated surge injection environment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.164-174
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• 2007

Phenomena of hydraulic transient such as water hammer should be analyzed to design the pipeline systems effectively in dam. Surge tanks generally are used to reduce change in pressure caused by hydraulic transient from load changes on the turbines. In this study, the appropriate scale of surge tank with chamber is investigated for dam safety management. The variation of water level in the surge tank are computed using governing equation. Using the Thoma-Jaeger's stability condition, static and dynamic stability are investigate for the cases of flood water level, normal high water level, rated water level and low water level. Finally appropriate diameters of shaft and chamber are determined in the surge tank with chamber.

• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.22-28
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• 2005

We investigated the characteristics of the overflow/wave overtopping, induced by the storm surge and high waves in Masan bay and Busan Coast during Typhoon 'Maemi', which landed at the southeast coast of the Korean peninsula on September, of 2003, causing a severe inundation disaster. Characteristics of the water level, increase by the overflow / wave overtopping, were discussed in two patterns. One is the increase of water level in the region, located inside of a bay, like Masan fishing port, and the waves are relatively small. The other is in the open sea, in which the waves act directly, as on the seawall in Suyong bay. In the former region, the water level increase was affected by the storm surge, as well as the long period oscillation and waves. In Masan fishing port, about $80\%$ of the water level increase on the quay wall was caused by the storm surge. In the latter one, it was greatly affected by the wave run-up. In Suyong bay, about $90\%$ of the water level increase on the seawall was caused by the wave run-up.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.4
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• pp.116-125
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• 2015

This paper presents experimental results obtained from actual installation conditions of surge protective devices (SPDs), with the aim of understanding the coordination of cascaded Class I and Class II SPDs. This paper also proposes effective methods for selecting and installing coordinating cascaded SPDs. The residual voltage of each SPD and the energy sharing of an upstream Class I tested SPD and a downstream Class II tested SPD were measured using a $10/350{\mu}s$ current wave. In coordinating a cascaded voltage-limiting SPD system, it was found that energy coordination can be achieved as long as the downstream SPD is a metal oxide varistor with a higher maximum continuous operating voltage than the upstream SPD; however, it is not the optimal condition for the voltage protection level. If the varistor voltage of the downstream SPD is equal to or lower than that of the upstream SPD, the precise voltage protection level is obtained. However, this may cause serious problems with regard to energy sharing. The coordination for energy sharing and voltage protection level is fairly achieved when the cascaded SPD system consists of two voltage-limiting SPDs separated by 3 m and with the same varistor voltage.

• Journal of the Korean earth science society
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• v.26 no.6
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• pp.560-572
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• 2005

This study investigates the characteristics of atmospheric circulation and the heat source $(Q_1)$ related to the winter cold surge in Korea from 1979 to 1999. The occurrence frequency of cold surge is about one event per year and $60\%$ of the total events occurred during the former period, before 1989. During the cold surge, the pressure pattern shows more dominant east-west dipole circulation pattern in the lower troposphere and the effect of upper level trough is stronger than normal cases. Temperature falling pattern over Korea shows that the pattern opposite to the temperature structure over Lake Baikal and temperature change has opposite signs between the low-middle level and upper level, with the boundary at 400 hPa. The analysis of heat source shows that atmospheric cooling by cold advection during the cold surge is balanced by adiabatic warming due to downward motion, indicating that the movement path of cold core is associated with that of heat sink. Therefore, the movement mechanism of the heat source and sink should be well known for understanding the maintenance mechanism of cold surge and predicting cold surges.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.2
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• pp.50-61
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• 2019

The aspects of typhoon-induced surges were classified into three types at the Western coast, and their characteristics were examined. The typhoons OLGA (9907) and KOMPASU (1007) were the representative steep types. As they pass close to the coasts with fast translation velocity, the time of maximum surge is unrelated to tidal phase. However, typhoons PRAPIROON (0012) and BOLAVEN (1215) were the representative mild types, which pass at a long distance to the coasts with slow translation velocity, and were characterized by having maximum surge time is near low tide. Meanwhile, typhoons MUIFA (1109) and WINNIE (9713) can be classified into mild types, but they do not show the characteristics of the mild type. Thus they are classified into propagative type, which are propagated from the outside. Analyzing the annual highest high water level data, the highest water level ever had been recorded when the WINNIE (9713) had attacked. At that time, severe astronomical tide condition overlapped modest surge. Therefore, if severe astronomical tide encounter severe surge in the future, tremendous water level may be formed with very small probability. However, considering that most of the huge typhoons are mild type, time of maximum surge tends to occur at low tide. In case of estimating the extreme water level by a numerical simulation, it is necessary not only to apply various tide conditions and accompanying tide-modulated surge, but also to scrutinize typhoon parameters such as translation velocity and so on.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.447-450
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• 2008

A storm surge is gradually increased in the Korean peninsula. Furthermore, this phenomenon is confined not only the Korean peninsula but also the whole world. A storm surge induced by storm, typhoon, or cyclone is a phenomenon that the water surface elevation is raising by the barometric pressure difference and this water level rising threatens the coastal facilities, settlement, or lives. Most of coastal region in our country are unsafe from this disaster. Even though we are not able to prevent the generation of this phenomenon, we can reduce the damages by investigating the kind of storm surge disaster. Once we finish this investigation, we can reduce the damages by offering the information for risk prior to an invasion of storm surge. This study, we analyzed the previously occurred storm surge damages, and this data can be utilized as a guide for those who live near the coastal region providing the information about the predicting scale of the storm surge

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.4
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• pp.28-34
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• 2012

Installing surge protection devices for a low-voltage system is important to ensure the survival of electric or electronic devices and systems. If surge protection devices (SPD) are installed without consideration of the concept of lightning protection zones, the equipment to be protected might be damaged despite the correct energy coordination of SPDs. This damage is induced by the reflection phenomena on the cable connecting an external SPD and the load protected. These reflection phenomena depend on the characteristics of the output of the external SPD, the input of the loads, and the cables between the load and the external SPD. Therefore, the SPD has an effective protection distance under the condition of the specific load and the specific voltage protection level of SPD. In this paper, PSCAD/EMTDC software is used to simulate the residual voltage characteristics of SPD Entering the low-voltage device. And by applying a certain voltage level, the effective protection distances of SPD were analyzed according to the each load and length of connecting cable, and the effectiveness of SPD were verified.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.2 no.2
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• pp.104-111
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• 1990

The water level variation due to the Typhoon around the coast of Pusan in the southern sea of Korea is investigated from the observed tidal record. Water level variations at six stations along the coast are discussed in association with the meteorological data. The characteristics of storm surge at Pusan during Typhoon Thelma in 1987 is analysed using the observed data, and it is performed the numerical simulation of storm surge which includes a inverse barometric effect due to the horizontal distribution of sea sur-face pressure. From the calculation results, the peak value of storm surge in the coast of Pusan was occur-red around the 01：00 July 16th, which is well coincident with the observed water level variation at the Kadukdo. However, the calculated value at the Pusan TBM is inconsistent with the observed one, which is regarded due to a reason that the Tidal Bench Mark (TBM) locates in the channel. In the computation results, the maximum surge occurs at the coast of Nakdong estuary, which is considered primarily due to a topographic effect, and water level variation exceeded 2.5 meter in these areas while only about 60 cm in another coasts.