• Wind and Structures
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• v.20 no.3
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• pp.449-468
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• 2015

Current wind-resistance designs of large-scale indirect dry cooling towers (IDCTs) exclude an important factor: the influence of the ventilation rate for radiator shutter on wind loads on the outer surfaces of the tower shell. More seemingly overlooked aspects are the effects of various ventilation rates on the wind pressure distribution on the tower surfaces of two IDCTs, and the feature of the flow field around them. In order to investigate the effects of the radiator shutter ventilation rates on the aerodynamic interference between IDCTs, this paper established the numerical wind tunnel model based on the Computational Fluid Dynamic (CFD) technology, and analyzed the influences of various radiator shutter ventilation rates on the aerodynamic loads acting upon a single and two extra-large IDCTs during building, installation, and operation stages. Through the comparison with the results of physical wind tunnel test and different design codes, the results indicated that: the influence of the ventilation rate on the flow field and shape coefficients on the outer surface of a single IDCT is weak, and the curve of mean shape coefficients is close to the reference curve provided by the current design code. In a two-tower combination, the ventilation rate significantly affects the downwind surface of the front tower and the upwind surface of the back tower, and the larger positive pressure shifts down along the upwind surface of the back tower as the ventilation rate increases. The ventilation rate significantly influences the drag force coefficient of the back tower in a two-tower combination, the drag force coefficient increases with the ventilation rate and reaches the maximum in a building status of full ventilation, and the maximum drag coefficient is 11% greater than that with complete closure.

• Journal of Korean Society of Disaster and Security
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• v.7 no.2
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• pp.9-16
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• 2014

Though the maintenance monitoring of structurally weak parts of the tunnel structure in public service must be judged in connection with the monitoring during the construction period for analysis of the behavior of the ground and surrounding structures following the tunnel excavation for the effective management, the monitoring during the construction period and the maintenance monitoring are implemented separately on the basis of the periods of construction and maintenance, so the connectivity and systematic management of the related data are mostly inadequate. The improvement direction is suggested in this thesis, by analyzing the problems of tunnel monitoring in the domestic design criteria. And, it is anticipated that from now on the use of hi-tech sensors and wireless communications technology will proceed vigorously in the maintenance, so considering these situations, the development and application of the maintenance monitoring system and the revision of the domestic design criteria and specification are needed in the future.

• Journal of the Society of Disaster Information
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• v.20 no.2
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• pp.379-389
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• 2024

Purpose and Method: Crowed Events can lead to sudden accidents caused by unpredictable variables. Therefore, focusing on the '10.29 Itaewon accident' among the representative cases, we examined the accident as the process of occurrence. In addition, improvement measures were suggested through analysis of related legal systems. Result: In the Itaewon accident, a "colony wave phenomenon" occurred due to "ultra-high-density cluster stay". In addition, cluster destruction occurred from a weak location in the cluster due to clusters and pressures in different directions to avoid this. Looking at the laws related to the safety management of Crowed Events, the laws and regulations differ depending on the location and type. Due to the complementary nature of the approach to the legal blind spot, the legal system that uses similar terms of the same concept and is not systematic is causing uncertainty in the application and interpretation of the law. Conclusion: Crowd control and on-site management should be carried out for events when the cluster density is expected to reach 8 people/m² or reached. Consistency should be maintained through the unified application of legislation to related legislation.

• Journal of the Korean GEO-environmental Society
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• v.20 no.10
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• pp.5-14
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• 2019

Recently, earthquakes have occurred in our country and seismic stability of high-rise buildings in large cities is being a growing interest and thus the related studies have been increased. Also the grounds are considered indirectly in most of seismic designs and analyses and seismic researches based on 3D dynamic analysis are insufficient. In this study, therefore, 2D and 3D dynamic analyses were performed based on the SSI complete model including grounds and the behavior was compared and analyzed. For dynamic modeling, linear time history analyses were performed by using MIDAS GTS NX. For this purpose, a high-rise building was assumed to be constructed on top of the bedrock and surrounded by a surface layer. A sensitivity analysis was performed with the selected parameters. The dynamic behavior was compared and analyzed in terms of horizontal displacements, drift ratios, bending stresses, and weak parts. In most cases, 2D dynamic behavior was calculated to be larger than 3D's and thus it shows more conservative results with increasing number and size of weak parts.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.712-722
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• 2020

Purpose: The damage from earthquakes with a magnitude of 5.0 or greater Korea has increased in South Korea. When a earthquake occurs, internal facilities and electric equipment besides urban structures will be damaged. Thus, in this paper, an earthquake-induced seismic isolation device with double slip fiction surfaces which can reduce the damage of electric power equipment such as distribution panel and then the seismic performance was evaluated. Method: To evaluate the seismic performance shaking table test was performed, a seismic performance comparison was performed according to the presence or absence of a seismic isolation device. The attenuation effect of the seismic isolation device are analyzed by comparing response acceleration and displacement for different frequencies and acceleration levels. Result: As a result of the test, the acceleration amplification was up to 42% less than when the seismic isolation device was installed in comparison to the other case without the seismic device. This is believed that the amplification energy has reduced because the displacement between the double slip friction surfaces of the seismic device play a role in dissipating the seismic energy. Conclusion: The seismic device with double slip friction surfaces has a greater earthquake attenuation effect in strong earthquakes than in weak ones, so the greater the frequency, the better the earthquake attenuation effect. Therefore, it is judged that earthquake energy can be decreased by applying to electric equipment such as distribution panels.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.109-112
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• 2008

The purpose of this study is to find out the characteristics of disasters caused by typhoons passing through the sea area around the Korean Peninsula. It analyzed two cases, that is, in WEST and EAST cases. These include the typhoons passing through the Yellow Sea, west of the Peninsula and East Sea, east of the Peninsula without landing on the Peninsula. FCM (Fuzzy Clustering Method) analysis was performed on typhoons affecting the Korean Peninsula from 1951 to 2006. The analysis shows that WEST case's cluster has the curved track of NE-S, and EAST case's cluster has the straight track of NE-SW. Typhoons that pass through the Yellow Sea have little change in frequency and the weak intensity. On the other hand, the frequency and the intensity of typhoons passing through the East Sea show the increasing trend. The characteristic of disasters by typhoons affecting the Korean Peninsula from 1973 to 2006 appears differently for each case: EAST cases caused significant damage in flooding, while WEST cases did damage in houses, ships, roads, and bridges. Rainfall amount and maximum wind speed data are analyzed in order to understand the impact of the typhoons, and the result indicates that the WEST cases are influenced by the wind, and East cases by precipitation. The result of this study indicates that the characteristic of disasters is distinctive according to the Typhoon's track. If applied to establish the disaster prevention plan, this result could make a contribution to the damage reduction.

• Journal of Coastal Disaster Prevention
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• v.4 no.1
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• pp.7-19
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• 2017

In this study, waves and currents observed by acoustic AWAC, VECTOR and Aquadopp Profiler in Anmok coastal waters were analysed to account for the variability of wave and current and to understand the mechanism of sediment transport generated by wave-induced current in the surf-zone. The monthly variation of wave and residual currents were analysed and processed with long-term observed AWAC data at station W1, located at the water depth of about 18m measured during from February 2015 to September 2016. Wave-induced currents were also analysed with intensive field measurements such as wave, current, suspended sediment, and bathymetry data observed at the surf-zone during in winter and summer. The statistical result of wave data shows that high waves coming from NNE and NE in winter (DEC-FEB) are dominant due to strong winds from NE. But in the other season waves coming from NE and ENE are prevalent due to the seasonal winds from E and SE. The residual currents with southeastern direction parallel to the shoreline are dominant throughout a year except in winter showing in opposite direction. The speed of ebb-dominant southeastern residual currents decreasing from surface to the bottom is strong in summer and fall but weak in winter and spring. By analysing wave-induced current, we found that cross-shore current were generated by swell waves mainly in winter with incoming wave direction about $45^{\circ}$ normal to the shoreline. Depending on the direction of incoming waves, longshore currents in the surf-zone were separated to southeastern and northwestern flows in winter and summer respectively. The variation of observed currents near crescentic bars in the surf-zone shows different direction of longshore and cross-shore currents depending on incoming waves implying to the reason of beach erosion generating the beach cusp and sandbar migration during high waves at Anmok.

• International Journal of Contents
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• v.10 no.1
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• pp.54-61
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• 2014

In this paper, we propose a pioneering concept of DPD(Disaster Prevention Design) to realize a securable society in the future. Features of danger in the future society are expected to be diverse, abrupt occurring, large scale, and complicated ways. Due to increment of dangers with their features of uncertainty, interactivity, complexity, and accumulation, human-oriented design concept naturally participates in activities to prevent our society against disasters effectively. We presented DPD is an essential design activity in order to cope with dangers expected in the future societies as well as realize securable environments. DPD is also an integrated design aids including preemptive protections, rapid preparing, recovery, and interactive cooperation. We also expect these activities of DPD is effective for generation of new values in the market, satisfaction of social needs, expansion of design industry, and a novel chance for development in the future society. Throughout this paper, we submit various aspects of DPD concepts including definition, classification, scope, necessity, strategy, influencing elements, process, and its principle. We expect these concepts will be the seed and/or basement of DPD research for the future works. For the direction of study for DPD in the future, we emphasize alarm system for preemptive protection rather than recovery strategy for the damage occurred. We also need to research about progressive prevention techniques and convergence with other areas of design. In order to transfer the concept of product design from facility-oriented mechanism to human-oriented one, we should develop new kinds of city basis facilities, public-sense design concepts referred to social weak-party, e-Learning content design preparing disasters, and virtual simulation design etc. On the other hand, we have to establish laws and regulations to force central and/or provincial governments to have these DPD strategies applying their regional properties. Modern design activities are expanding to UI(user interface) content design area overcoming the conventional design concept of product and/or service. In addition, designers are recognized as art directors or life stylists who will change the human life and create the social value. DPD can be divided into prevention design, preparedness design, response design, and recovery design. Five strategies for successful DPD are Precaution-oriented, Human-oriented, Sense-oriented, Legislation, and Environment Friendly Strategies.

• Journal of the Korean Institute of Educational Facilities
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• v.27 no.1
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• pp.3-10
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• 2020

Due to the frequent occurrence of large-scale disasters such as recent earthquakes, the problem of the safety of old school buildings has emerged. The need to secure safety management technology through constant monitoring is increasing in an attempt to supplement old school buildings with weak disaster response capabilities. Traditional research is approaching the development of an existing sensor-based risk precursor information monitoring system. However, unlike this, in this study, we will focus on the development of a data analysis platform as part of the development of a continuous monitoring system that can be prepared for earthquakes, collapses, and fires, based on constantly measured data. For this reason, the development of a safety diagnostic algorithm based on the optimal sensor-attached points and sensor data reflecting the fragile characteristics of old school buildings was derived. Utilizing this, a message and action manual system for each management / use entity of school buildings after retirement was constructed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.665-668
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• 2007

The location based service means the service using the location information and the service used based on the location information comes into the spotlight as the critical information of the future mode townsman ubiquitous-City construction. LBS settles down as the core element of ITS or the telematics as the cutting edge technology appearing according to the power generation of the mobile communication technology and recently gradually broadens a range to the public safety service including the distribution management, the asset management, a children and old and the weak protection means, the disaster preparation rescue service like the E-911 of U.S. In the national, the technical regulations about the ground wave LBS was established at November 2005 for the first time in the country. but it actually operated and problems were deduced. Therefore, in this paper, domestic and foreign LBS usage trend and technical standards case try to be analyzed for the revision of the technical regulations of the ground wave LBS serviced in the national and the national technical standards bill for the revision tries to be prepared based on this.