• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.2
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• pp.139-145
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• 2017

Recently, gusts, typhoon and tsunamis have been occurring more frequently around the world. In such an emergency situation, a moored vessel can be used to predict and analyze other vessel behavior, but if the mooring system is destroyed, marine casualties can occur. Therefore, it is necessary to determine quantitatively whether a vessel should be kept in the harbour or evacuate. In this study, moored ship safety in an exclusive wharf according to swell effects on motion and mooring load have been investigated using numerical simulations. The maximum tension exerted on mooring lines exceeded the Safety Working Load for intervals 12 and 15 seconds. The maximum bollard force also exceeded 35 tons (allowable force) in all evaluation cases. The surge motion criteria result for safe working conditions exceeded 3 meters more than the wave period 12 seconds with a wind speed of 25 knots. As a result, a risk rating matrix (risk category- very high risk, high risk and moderate risk) was developed with reference to major external forces such as wind force, wave height and wave periods to provide criteria for determining the control of capabilities of mooring systems to prevent accidents.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.1
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• pp.10-18
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• 2018

Recently, a port city has been gradually expanding near coastal area, and many facilities for tourism and waterfront have been constructed near the shore. When storm surge developed by typhoon have occurred, coastal facilities have a lot of damage and failure with loss of life caused directly by the waves. Various barriers have been suggested to protect property and human life from disasters, they have not been widely applied though. Because they do not satisfy the recent trends that emphasize the surrounding scenery. In this study, a moveable barrier on revetment is proposed against wave overtopping. This moveable barrier has two function, sightseeing and protecting. In case of usual day, it is installed on the revetment and used observatory deck for sightseeing. When wave overtopping has occurred by storm surge, it protect coastal area through changing of flat deck to triangular barrier. The hydraulic and the structural performance of the newly proposed movable barrier was investigated through numerical analysis using commercial program. As a results, this structure has numerically good performance, and follow-up research is required through experimental tests though.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6B
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• pp.709-721
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• 2008

This paper is to test the applicability of ModKIMSTORM (Modified KIneMatic Wave STOrm Runoff Model) by applying it to Namgangdam watershed of $2,293km^2$. Model inputs (DEM, land use, soil related information) were prepared in 500 m spatial resolution. Using five typhoon events (Saomi in 2000, Rusa in 2002, Maemi in 2003, Megi in 2004 and Ewiniar in 2006) and two storm events (May of 2003 and July of 2004), the model was calibrated and verified by comparing the simulated streamflow with the observed one at the outlet of the watershed. The Pearson's coefficient of determination $R^2$, Nash and Sutcliffe model efficiency E, the deviation of runoff volumes $D_v$, relative error of the peak runoff rate $EQ_p$, and absolute error of the time to peak runoff $ET_p$ showed the average value of 0.984, 0.981, 3.63%, 0.003, and 0.48 hr for 4 storms calibration and 0.937, 0.895, 8.08%, 0.138, and 0.73 hr for 3 storms verification respectively. Among the model parameters, the stream Manning's roughness coefficient was the most sensitive for peak runoff and the initial soil moisture content was highly sensitive for runoff volume fitting. We could look into the behavior of hyrologic components from the spatial results during the storm periods and get some clue for the watershed management by storms.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.78-84
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• 2008

Inundation of substation and ground power equipment broke out every summer season in low-lying downtown and low-lying shore by localized heavy rain, typhoon and tidal wave. In case inundation excluding the exchanging cost of equipment, it occurs a great economic and social loss owing to recovery time and events of electric shock occur by inundation electrical facility. So we researched the installation situation of substation and power equipment and inundation loss at Flood Danger Area. And we analyzed refutation or law relating to the flood protection counterplan of US, England Australia. We present flood protection countermeasures by survey and analyzing the internal standard and his paper will be used to resent a reform proposal of electrical feinted law about flood protection.

• Wind and Structures
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• v.19 no.3
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• pp.249-270
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• 2014

Through comparing the mean wind profiles observed overland during the passages of four typhoons, and the gradient wind speeds calculated based on the sea level pressure data provided by a numerical model, the present paper discusses, (a) whether the gradient balance is a valid assumption to estimate the wind speed in the height range of 1250 m ~ 1750 m, which is defined as the upper-level mean wind speed, in a tropical cyclone over land, and (b) if the super-gradient feature is systematically observed below the height of 1500 m in the tropical cyclone wind field over land. It has been found that, (i) the gradient balance is a valid assumption to estimate the mean upper-level wind speed in tropical cyclones in the radial range from the radius to the maximum wind (RMW) to three times the RMW, (ii) the super-gradient flow dominates the wind field in the tropical cyclone boundary layer inside the RMW and is frequently observed in the radial range from the RMW to twice the RMW, (iii) the gradient wind speed calculated based on the post-landfall sea level pressure data underestimates the overall wind strength at an island site inside the RMW, and (iv) the unsynchronized decay of the pressure and wind fields in the tropical cyclone might be the reason for the underestimation.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.80-83
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• 2007

Entering 21st century, various natural disasters have been caused by the scorching heat wave, earthquake, tsunami, typhoon and so on. The casuality and damages have been drastically increased in terms of the frequency and magnitude. Therefore, 50 nations around the world agreed to build up the GEO(Global Earth Observation) in charge of the earth observation for the understanding of the earth system changes, monitoring and prediction and it is on operation. To keep the pace with GEOSS for the cooperation of Science & Technology and to successfully achieve the GEOSS project, KGEO office was established and has been on its duty. Moreover, for more prosperous building of the GEOSS, in cooperation with KGEO and KISTI(Korea Institute of Science and Technology Information), we've conducted the survey of the domestic situation about 9 societal benefit areas of the GEOSS. This survey consists of 5 sections as follows: the standardization, the information system management, the raw data and metadata, the infrastructure, and the others. This survey results will be used as the basic material for establishing the National Global Earth Observation System.

• Economic and Environmental Geology
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• v.39 no.4 s.179
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• pp.495-505
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• 2006

Atmospheric infrasound is defined as low frequency inaudible sound waves generated from natural phenomena and human activities. One property of long-distance travelling of infrasound makes it possible to detect the wave propagated from remote sound sources and to understand many geophysical phenomena generating it. Recently, advanced global infrasound sensor arrays are being deployed to monitor the clandestine nuclear test and to study geophysical phenomena in the world. In Korea, five seismo-acoustic arrays consisting of co-located seismometer and micro-barometer have been operated to discriminate the artificial explosions from the natural earthquakes in and around the Korean Peninsula. In addition to the discrimination purpose, these ways also record distinct infrasonic signals from natural phenomena on global scale such as large earthquake, bolide event, volcanic explosion, typhoon, and so on. As a new frontier in monitoring the earth, infrasound is being applied to understand various phenomena in and above the earth's surface.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.281-284
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• 2008

Inundation of substation and ground power equipment breaks out every summer season in low-lying downtown and low-lying shore by localized heavy rain, typhoon and tidal wave. In case inundation excluding the exchanging cost of equipment, it occurs a great economic and social loss owing to recovery time and events of electric shock occur by inundation electrical equipment(Pad-mounted Transformer and Switch). In case of installing the power equipment at flood danger territory, we are necessary to the product development, the product is that water does not come in the inside the power equipment. Product of pressure maintaining are established on the basic frame and sensor operates at the flooding occurrence and is maintained a shutting tightly structure and it is a method. The product which is produced the reliability of the product it confirmed a flooding yes or no from the condition which puts in the water tank and it verified. We estimate that loss cost which is caused by with flooding and the power failure will be diminished if it is addition to advances the reliability evaluation and a security of the flood protection product.

• Atmosphere
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• v.26 no.1
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• pp.85-95
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• 2016

In this study, we investigated the variabilities of wind speed of 850 hPa and precipitable water over the East Asia region using the NCEP Final Analysis data from December 2001 to November 2011. A large variance of wind speed was observed in northern and eastern China during the winter period. During summer, the regions of the East China Sea, the South Sea of Japan and the East Sea show large variances in the wind speed caused by an extended North Pacific High and typhoon activities. The large variances in the wind speed in the regions are shown to be correlated with the inter-annual variability of precipitable water over the inland region of windward side of the Korean Peninsula. Based on the investigation, sensitivity tests to the domain size were performed using the WRF model version 3.6 for heavy precipitation events over the Korean Peninsula for 26 and 27 July 2011. Numerical experiments of different domain sizes were set up with 5 km horizontal and 50 levels vertical resolutions for the control and the first experimental run, and 9 km horizontal for the second experimental run. We found that the major rainfalls correspond to shortwave troughs with baroclinic structure over Northeast China and extended North Pacific High. The correlation analysis between the observation and experiments for 1-h precipitation indicated that the second experiment with the largest domain had the best performance with the correlation coefficient of 0.79 due to the synoptic-scale systems such as short-wave troughs and North Pacific High.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.114-122
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• 2014

Currently, global warming has become a serious problem arising from the usage of fossil fuels such as coal and petroleum. Moreover, due to the global warming, heat wave, heavy snow, heavy rain, super typhoon are frequently occurring all over the world. Due to these serious natural disasters, concrete structures and infrastructures are seriously damaged or collapsed. In order to handle these problems, climate change oriented construction technology and codes are necessary at this time. Therefore, in this study, the validity of the present concrete mixture proportions are evaluated considering temperature and humidity change. The specimens cured at various temperature and humidity conditions were tested to obtain their compressive and split tensile strengths at various curing ages. Moreover, performance based evaluation (PBE) method was used to analyze the satisfaction percentage of the concrete cured at various condition. From the probabilistic method of performance evaluation of concrete performance, feasibility and usability can be determined for future concrete mix design.