• Journal of the Korean Society of Hazard Mitigation
• /
• v.3 no.4 s.11
• /
• pp.119-129
• /
• 2003

Concrete and steel are essential structural materials in the construction. But, concrete, different from steel, consists of many materials and is affected by many factors such as properties of materials, site environmental situations, and skill of constructors. Concrete have two kinds of properties, immediately knowing properties such as slump, air contents and time dependent one like strength. Therefore, concrete mixes depend on experiences of experts. However, at point of time using High Performance Concrete, new method is wanted because of more ingredients like mineral and chemical admixtures and lack of data. Artificial Neural Networks(ANN) are a mimic models of human brain to solve a complex nonlinear problem. They are powerful pattern recognizers and classifiers, also their computing abilities have been proven in the fields of prediction, estimation and pattern recognition. Here, among them, the back propagation network and radial basis function network ate used. Compositions of high-performance concrete mixes are eight components(water, cement, fine aggregate, coarse aggregate, fly ash, silica fume, superplasticizer and air-entrainer). Compressive strength, slump, and air contents are measured. The results show that neural networks are proper tools to minimize the uncertainties of the design of concrete mixtures.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.8 no.4
• /
• pp.119-122
• /
• 2008

The paved area like a road or bridge where having high impermeable rates were accumulated various non-point sources(NPS) by passing vehicles during dry season periods. They are flowed in the river continuous when it rains and could negative impact on environment. Therefore, this study monitoring NPS for two years and determinating for each pollutant EMCs and mass loading. The result shows that the EMC ranges are 11.60$\sim$230.90 mg/L for TSS, 4.58$\sim$31.90 mg/L for BOD, 1.86$\sim$9.20 mg/L for TN and 0.14$\sim$1.55 mg/L for TP. Also, the ranges of washed-off mass loading are determined to 0.78$\sim$18.01 kg/day for TSS, 0.47$\sim$1.17 kg/day for BOD, 0.00$\sim$0.01 kg/day for Pb and 0.01$\sim$0.06 kg/day for Zn.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.8 no.4
• /
• pp.75-79
• /
• 2008

As Information Technology developed, Information requirement has been went higher. In the field of GIS(Geographic Information System) more information is processed more quickly and accurately. Especially, quick analysis of forest fire information (topography, ignition point, weather condition, etc.) over a wide area is essential in order to minimize victim, environmental damage, and economical damage, decide course of evacuating, estimate a fire spread course, and attack resource arrangement. We determined a fire spread distance at each unit time through an experiment with various slope degrees and distinction of flat, upslope and downslope. For the tests on the upslope, as the slope increased, the rate of spread increased. On the downslope in contrast with the upslope, as the slope increased, the rate of spread decreased. We analyzed a spread rate of forest fire on each slope as the method classified upslope(+) and downslope(-) using the results obtained from the experiment. Consequently, the proposed method is able to be used to effectively support the attack of forest fire by providing accurate predictions of fire spread.

• Journal of Labour Economics
• /
• v.26 no.3
• /
• pp.181-207
• /
• 2003

The purpose of this study was to conduct a dynamic analysis of married women's return to the workforce following first childbirth. We have based our investigation on the data compiled by the KLIPS, where the workforce performance is the focal point of it's research, and by these materials, this study has analyzed the aspects of the factors that decide post-childbirth return to the workforce. We have applied the Cox Regression Hazard Model, where corroborative evidence are statistically applied. The following are the conclusions that were derived from this research: First, according to the study, academic background is a vital factor in reducing the gap and time of women's return to the workforce. Second, whether having active child-care after giving birth or not doubles the chances of women returning to the workforce. Third, if the pre-birth employment form was a wage-work and the rate of returning to the workforce was lower than the non-wage, relatively speaking, this reflects that the non-wage form of work, which provides a better possibility to return to the workforce after giving birth, could be another way to prevent women's career discontinuation.

• Journal of Korean Society for Geospatial Information Science
• /
• v.13 no.2 s.32
• /
• pp.45-50
• /
• 2005

Recently, slope failures are disastrous when they occur in mountainous area adjoining highways. The accidents associated with Slope failures have increased due to rapid urbanization of mountainous area. Therefore, the inspection of slope is conducted to maintain road safety as well as road function. In this study, we apply to the remedy which is comparing existent description to advanced technology using GIS. we utilize a 3D scanner, one of the advanced method, to generate precise and complete road slope model from expert point of view. In result, we are transferred practical data from external slope stability to hazard slope information. We suggest not only the database but also the method of road risk evaluation based on GIS.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.4 no.3 s.14
• /
• pp.33-41
• /
• 2004

The purpose of this study is to analyze the relationship between El Nino phenomena and the monthly rainfall variations of Seoul city which is composed of 30 year data during $1967{\sim}1996$. In this study, the monthly rainfall data at Seoul city is analyzed by applying an intervention model. As it is unavailable to get the data of El Nino phenomena, the point of intervention have been decided from the literature survey of the data observed to be the years of 1972, 1976, 1979, 1982, 1986 and 1991. As a results the El Nino was revealed more significant to the monthly rainfall at Seoul. In addition, monthly rainfall varied between the maximum 53.41mm and the minimum 2.50mm. To prevented future natural disaster, long term water planning and management is requied in consideration El $Nin\tilde{o}$.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.7 no.2 s.25
• /
• pp.53-63
• /
• 2007

This study is to evaluate the probable snowfall depth by the point frequency analysis and to draw the map of probable snowfall depth in Korea. The 14 probability distributions which has been widely used in hydrologic frequency analysis are applied to the annual maximum depth of snowfall data. The parameters of each probability distribution are estimated by method of moments, maximum likelihood method and method of probability weighted moments. The estimated parameters were checked by parameter validity conditions of each assumed probability distribution. Four tests that are $X^2-test$, Kolmogorov-Smirnov test, Cramer von Mises test and probability plot correlation coefficient test are used in this study to determine the goodness of fit of the distributions. Mostly the 2-parameter gamma distribution was determined as appropriate distribution for the annual maximum new snowfall depth. The probable snowfall depth were obtained from appropriate distribution for the selected return periods and the maps of probable snowfall depth were presented. It will be useful to specify the snowfall load for the design of agricultural facilities such as vinyl house and cattle shed.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.1225-1234
• /
• 2009

As the Wenchuan Earthquake was of high magnitude and shallow seismic focus, it caused great damage and serious geo-hazards. By the field investigation and remote-sensing interpretation after the earthquake and by using means of GIS, the distribution of geo-hazards triggered by the earthquake was analyzed and the conclusions are as follows: (1) the earthquake geo-hazards showed the feature of zonal distribution along the earthquake fault zone and linear distribution along the rivers; (2) the distribution of earthquake geo-hazards had a marked hanging wall effect, for the development density of geo-hazards in the hanging wall of earthquake fault was obviously higher than that in the foot wall and the width of strong development zone in the hanging wall was about 10 km; (3) the topographical slope was a main factor which controlled the development of earthquake geo-hazards and a vast majority of geo-hazards were distributed on the slopes of 20 to 50 degrees; (4) the earthquake geo-hazards had a corresponding relationship with the elevation and micro-landform, for most hazards happened in the river valleys and canyon sections below the elevation of 1500 to 2000 m, particularly in the upper segment of canyon sections (namely, the turning point from the dale to the canyon). Thin ridge, isolated or full-face space mountains were most sensitive to the seismic wave, and had a striking amplifying effect. In these areas, collapses and landslides were most likely to develop; (5) the study also showed that different lithologies determined the types of geo-hazards, and usually, landslides occurred in soft rocks, while collapses occurred in hard rocks.

• Nuclear Engineering and Technology
• /
• v.21 no.3
• /
• pp.171-185
• /
• 1989

On the basis of equal health hazard risk, economic assessment of nuclear was compared with that of coal for the expansion planning of electric power generation in the year 2000. In comparing health risks, the risk of coal was roughly ten times higher than that of nuclear according to various previous risk assessments of energy system. The zero risk condition can never be achievable. Therefore, only excess relative health risk of coal over nuclear was considered as social cost. The social cost of health risk was estimated by calculation of mortality and morbidity costs. Mortality cost was ＄250,000 and morbidity cost was ＄90,000 in the year 2000.(1986US＄) Through Cost/Benefit Analysis, the optimal emission standards of coal-fired power generation were predicted. These were obtained at the point of least social cost for power generation. In the year 2000, the optimal emission standard of SOx was analyzed as 165ppm for coal-fired power plants in Korea. From this assessment, economic comparison of nuclear and coal in the year 2000 showed that nuclear would be more economical than coal, whereas uncertainty of future power generation cost of nuclear would be larger than that of coal.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.6 no.3 s.22
• /
• pp.9-16
• /
• 2006

In structural health monitoring, the safety of structural members are assessed by the level of stress measured by various strain sensors based on different sensing mechanisms. Since most existing strain sensors used for health monitoring system can cover a relatively small range of structural members, it is very difficult to measure the maximum value of the member subjected to varying amount and types of loads with those point sensors. The reliability of assessed safety of a member may be improved by increasing the number of sensors. It may not be also realistic to increase the number of sensors to overcome these drawbacks. In this paper, a stress measuring method for beam-column members is developed by estimating the maximum stress based on the average strains obtained from long gauge sensor. The average strain from long gage fiber optic sensor is transformed into the maximum strain by multiplication of the modification factor derived in this research.