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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Korean Society of Hazard Mitigation
Journal Basic Information
Journal DOI :
Korean Society of Hazard Mitigation
Editor in Chief :
Moo Jong Park
Volume & Issues
Volume 9, Issue 6 - Dec 2009
Volume 9, Issue 5 - Oct 2009
Volume 9, Issue 4 - Aug 2009
Volume 9, Issue 3 - Jun 2009
Volume 9, Issue 2 - Apr 2009
Volume 9, Issue 1 - Feb 2009
Selecting the target year
A Study on Moment Gradient Factor for Inelastic Lateral-Torsional Buckling of Stepped I-Beam Subjected to Uniformly Distributed Load and End Moment
Son, Ji-Min ; Park, Jong-Sup ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 1~9
This paper investigates inelastic lateral-torsional buckling of stepped beams subjected to uniformly distributed load and end moments. A three-dimensional finite-element program ABAQUS (2007) and a regression program MINITAB(2006) were used to analytically develop new design equation for singly and doubly stepped beams with simple boundary condition. The flanges of the smaller cross-section in the stepped beams were fixed at 30.48 by 2.54 cm, whereas the width and thickness of the flanges of the larger cross-section varied. The web thickness and height of the beams were kept at 1.65 cm and 88.9 cm, respectively. The ratios of the flange thickness, flange width, and stepped length of beam are considered with analytical parameters. Two groups of 27 cases and 36 cases, respectively, were analyzed for doubly and singly stepped beams in the inelastic buckling range. The combined effects of residual stresses and geometrical imperfection on inelastic lateral-torsional buckling of beams are considered. The distributions of residual stress of the cross-section is same as shown in Pi and Trahair (1995) and the initial geometric imperfection of the beam is set by central displacement equal to 0.1% of the unbraced length of beam. The comparisons between results from proposed equations and the results from finite element analyses were presented in this paper. The maximum differences of two results are of 13% for the doubly stepped beam and 10% for the singly stepped beam. The proposed equations definitely improve current design methods for the inelastic lateral-torsional buckling problem and increase efficiency in building and bridge design.
Physical Properties of Lightweight and Normal Weight Concretes due to Water-Cement Ratio Changes
Lee, Chang-Soo ; Kim, Jae-Nam ; Lim, Youn ; Ma, Moon-Hak ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 11~20
By using the artificial lightweight aggregate for the natural aggregate depletes and destruction of environment and the application of lightweight concrete in structure, the lightweight concrete is manufactured. The fundamental characteristics by the waterbinder ratio was evaluated. It is suggested the method to control of pre-absorbed water of the lightweight aggregate. Lightweight concrete with pre-absorbed aggregate has similar characteristics compared to normal weight concrete regardless of water-binder ratio. According to the water-binder ratio, the drying condition, and the rebar, the unit mass of the lightweight concrete showed the reduction of 14.6
21.0% as the range of 1,668
in comparison to the normal weight concrete. The lightweight aggregate pre-absorbed water showed the deferent evaporation quantity according to the water-binder ratio. As the water-binder ratio is lower, the oven dry vapour water is larger, therefore the internal curing water is increasing. In the same water-binder, comparing the normal concrete the lightweight concrete shows lower compressive strength which is due to the different strength of an aggregate. In the air dry curing, the normal weight concrete has a lower strength improvement effect in w/c 0.3 than the ratio 0.4 and 0.5. However, the strength improvement effect has increasing as the water-binder ratio was low in the light concrete.
Risk Assessment of Strong Wind over Industrial Facilities in Shipyards
Lee, Sung-Su ; Kim, Hak-Sun ; Lee, Young-Kyu ; Shim, Kyu-Cheoul ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 21~28
Most of domestic shipyards are located at coastal regions which are affected by typhoons nearly every year. For effectiveness of shipbuilding, shipyards contain many facilities which are light-weighted and affected dominantly by wind. In the present paper, we analyze various wind fields over a shipyard including surrounding topology and structures to evaluate the structural safety of the facilities posed in the strong wind. Extreme wind speed for a study region was estimated by typhoon Monte Carlo simulation and then used for inlet wind speed for CFD analysis for wind load on the facilities. Considering geometrical wind effects, we assess the surface pressure of the elements as the pressure factor, the ratio of surface pressure to dynamic pressure. The results show that the simulated wind speed is greater than the design wind speed for the some facilities because of the shipyard's geometry. It also shows that surrounding topography in coastal area is needed to be considered and adjustment for design wind speed at wind load standard application is necessary for mooring ship and industry facilities.
The Quantative Homogeneity Analysis of Seoul Rainfall
Hwang, Seok-Hwan ; Kim, Joong-Hoon ; Yoo, Chul-Sang ; Yoo, Do-Guen ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 29~35
In this study, quantitative homogeneity analysis was performed between rainfall observation data set of Chukwooki(CWK) and rainfall observation data set of modern rain gage(MRG) using statistical methods such as basic statistics, K-S test and Boxplots. To analyze the homogeneities of CWK and MRG four rainfall characteristic series such as monthly rainfall, the ratio of maximum daily rainfall to monthly rainfall, number of rainy days for each month, and the ratio of monthly rainfall to numbers of rainy days are made, and the homogeneity tests using two sample K-S test and quantitative comparisons were performed. The test results showed that observation precisions between CWK and MRG of original data set(M00) were differed because M00 clearly showed the statistical significances on differences of numbers of monthly rainy days of CWK and MRG. But, rainfall showed a little differences which were not significant between CWK and MRG.
Characteristics of Strong Wind Occurrence in the Southwestern Region of Korea
Kim, Baek-Jo ; Lee, Seong-Lo ; Park, Gil-Un ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 37~44
The characteristics of strong wind occurring over the southwestern part of the Korean peninsula are analyzed by using hourly mean wind data observed in Gusan, Mokpo, Yeosu and Wando from 1970 to 2008. The strong wind here is defined as wind speed of more than 13.9 m/s according to Korea Meteorological Administration (KMA)'s strong wind advisory. The causes of strong wind are classified into typhoon, monsoonal (wintertime continent polar air mass) and frontal (cyclone) winds. Typhoon wind is characterized by abrupt change of its speed and direction after and before landfall of typhoon and monsoonal wind by periodicity of wind speed. And frontal wind tend to be changed from southwesterly to northwesterly at observation site with location of frontal surface. Strong winds are mainly occurred in Yeosu by typhoon, Gusan and Mokpo by monsoonal wind, and Mokpo and Yeosu by frontal wind. In particular, in case of frontal wind, the frequency of strong wind in Mokpo decreases while in Yeosu it increases. Monthly frequency of strong wind is high in August in Mokpo and September in Yeosu by typhoon, January in Gusan and December in Mokpo by monsoonal wind, and in April in Mokpo and Yeosu by frontal wind. The duration less than 1 hour of strong wind is prominent in all stations.
An Analysis of Maintenance Cost of Preventive Optimized-Rehabilitation Area Method in Asphalt Concrete Pavement
Kim, Nak-Seok ; Hong, Eun-Cheol ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 45~51
The paper presents the economic analysis of optimized-rehabilitation area method considered as one of the preventive maintenance methods in asphalt concrete pavement. The optimized-rehabilitation area was selected based on the analysis of traffic lane characteristics. The main concept of the selected method was to minimize the maintenance cost. The effective width of traffic lane in this method was 70 cm of each wheel path. According to the traffic survey conducted in this research, more than 95% of vehicles passed within the width of each wheel path. The new preventive optimized-rehabilitation area method showed less maintenance cost than the conventional overlay. In addition, traffic congestions and the user cost can be reduced. The research results revealed that the total maintenance cost was reduced by 35% by using the new method compare to the conventional one.
Particle Shape Evaluation of Aggregate using Digital Image Process
Hwang, Taik-Jean ; Cho, Jae-Yoon ; Lee, Kwan-Ho ; Song, Young-Sun ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 53~59
The purpose of this research is particle shape evaluation of granular soil and aggregate using Digital Image Process(DIP). DIP is very useful to measure the roughness and particle shape of aggregates. Couple of aggregates, like standard sand, two different crushed stones, and two different marine aggregates, have been employed. Shape factor of two different marine aggregates is ranged 0.35 to 0.54. Crushed stone I is that of 0.74 which is highly flat, but standard sand is elongated shape. Especially, two marine aggregate showed a big difference of width and length which meaned a long shape. There is any significant difference of elongation ratio and flakiness for each aggregate with different measuring system, like direct measurement of vernier calipers and DIP method. Within the limited test results, DIP is one of useful to get the particle shape of aggregate with limitation of measuring errors and to apply the particle distribution curve.
The Scope of Risk, Crisis, and Disaster Management in Wide and Narrow Sense
Chung, Ji-Bum ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 61~66
This study examines the definitions and the scopes of risk, crisis, and disaster management in narrow and wide sense. Generally, the meanings and the scopes of these terms have been used in a very confused manner, and that is the main reason of the difficulty of interdisciplinary approach to disaster related study. In a practical manner, these terms needs to be defined more correctly, for the effective communications among various fields of academic and professional disciplines. This study tries to divide the meanings and the scopes of risk management, disaster management, and crisis management in narrow and wide sense, to define them in a more elaborate manner. Though these three terms can be distinguished in narrow sense, they have almost same meanings when we use them in wide sense.
A Study on Activation of Occupational Safety and Health Agency for Reducing Industrial Accidents
Kim, Yun-Seon ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 67~70
First of all, this paper investigated scrupulously Occupational Safety and Healthy Agencies which take care of nucleus roles as accident protection organ of industrial circles in our country. Catching hold of elaborately lots of problems that each Agency holds, we tried to action to correct that faulty custom and invalidism. On the other hand, we exhort and encourage more available measures helping practically to protect industrial accident of work place receiving vicarious execution. Furthermore, both in name and reality, we try to be reborn as a mission institution of accidental prevention of medium and small work place. Therefore, the purpose of the present paper is to suggest substantial counterproposal for activation of Occupational Safety and Healthy Agency.
Flood Risk Estimation Using Regional Regression Analysis
Jang, Ock-Jae ; Kim, Young-Oh ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 71~80
Although desire for living without hazardous damages grows these days, threats from natural disasters which we are currently exposed to are quiet different from what we have experienced. To cope with this changing situation, it is necessary to assess the characteristics of the natural disasters. Therefore, the main purpose of this research is to suggest a methodology to estimate the potential property loss and assess the flood risk using a regional regression analysis. Since the flood damage mainly consists of loss of lives and property damages, it is reasonable to express the results of a flood risk assessment with the loss of lives and the property damages that are vulnerable to flood. The regional regression analysis has been commonly used to find relationships between regional characteristics of a watershed and parameters of rainfall-runoff models or probability distribution models. In our research, however, this model is applied to estimate the potential flood damage as follows; 1) a nonlinear model between the flood damage and the hourly rainfall is found in gauged regions which have sufficient damage and rainfall data, and 2) a regression model is developed from the relationship between the coefficients of the nonlinear models and socio-economic indicators in the gauged regions. This method enables us to quantitatively analyze the impact of the regional indicators on the flood damage and to estimate the damage through the application of the regional regression model to ungauged regions which do not have sufficient data. Moreover the flood risk map is developed by Flood Vulnerability Index (FVI) which is equal to the ratio of the estimated flood damage to the total regional property. Comparing the results of this research with Potential Flood Damage (PFD) reported in the Long-term Korea National Water Resources Plan, the exports' mistaken opinions could affect the weighting procedure of PFD, but the proposed approach based on the regional regression would overcome the drawback of PFD. It was found that FVI is highly correlated with the past damage, while PFD does not reflect the regional vulnerabilities.
A Study on the Dimensionless Flood Waves for the Unsteady Seepage Analysis of the Levees
Jeon, Se-Jin ; Kwon, Kyung-Jun ; Ahn, Won-Sik ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 81~89
The seepage should be analyzed to design or reinforce the levees. The steady seepage analysis is an usual application in USA and European countries where the large scaled dams and levees are existed. However, Korea and Japan, where the reaching time is short, the excessive forces are applied on the levees at the short reaching time if the seepages are analyzed in steady condition. Accordingly, the unsteady analysis based on the variation of time is necessitated. In the unsteady analysis, the flood wave type is necessary. No criteria and standards, however, are derived for the unsteady seepage in Korea. In the study, the flood wave type is derived for the unsteady seepage. The major reliable flood surface data are collected in 5 stations including Jindong of the Nakdong river basin. The data are sorted in duration, and they are non-dimensionalized. The statistical method is also applied to derive the waves. To verify the study, the seepage is analyzed by the derived wave and applied to the prototype. The results are also compared with the Japanese Method. The errors between the hydraulic gradient and critical velocity method are
at the Jindong,
at the Hyunpoong,
at the Waegwan,
at the Nakdong, and
at the Jeongam, respectively. The relationship(
) between each method is relatively high as
. This means the results are more logical than the Japanese method, and the study is applicable to the design of hydraulic structures.
2-D Analysis of the Low Flow Variation Around the Bridge Pier
Yeon, In-Sung ; Lee, Jai-Kyung ; Yeon, Gyu-Bang ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 91~97
The flow is changed by the structure which goes across the river. The structure with debris causes high water level and overflow. The changed flow, which caused by pier and stream characteristics like velocity and slope, was analysed by 2D model. After rainfall, the influences of increased discharge were evaluated. Velocity was simulated in the channel by SMS (Surface water Modeling System) using RMA2, and high velocity values were found in the steep and narrow reach. Highest velocity value around piers was showed in the middle of space between two piers. The increased discharge due to rainfall increases velocity and changes flow contour considerably.
An Experimental Study on the Analysis of Infiltration Capacity of the Permeable Block
Lee, Hoon ; Jung, Do-Joon ; Kim, Young-Bok ; Kim, Yun-Tae ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 99~106
This research was to estimate quantitative infiltration volume of permeable block which is one of runoff reduction infiltration facilities. In this research, the permeable block experiments estimating infiltration volume for 50, 100, 150, 200 mm/hr rainfall intensity were carried out and hydraulic experiments results were compared with numerical simulation output to produce feasibility of numerical simulation. Final infiltration capacity analysis of permeable block hydraulic experiments reveals that every estimated infiltration volume before runoff beginning was above approximately 300.0 l despite rapid reduction of infiltration ratio and runoff initiation time were occurred in every rainfall intensity. Statistical calculation for coefficient of determination based on cumulative infiltration volume of hydraulic experiment and numerical simulation resulted in a high correlationship as
A Study on Characteristics of Sedimentation Rate of Suspended Fine Particles under Floc Size and Density
Kim, Jong-Woo ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 107~113
This paper considers the influence of floc on the sedimentation rate for the cohesive material. The effects of floc density and size changes were also taking into consideration during the experiment. The settling velocity of a discrete floc was measured in a quiescent water column. Floc diameter and density were investigated using a modified Stokes equation with some constants such as water density, viscosity, material density and the floc fractal dimension
obtained from the relationship between the floc diameter and the floc settling. The floc diameter of quartz and alumina increased at increasing initial concentrations. The floc size of quartz with increasing NaCl concentration varied between approximately 0.8 um to
. Floc density decreased as floc size increased. The floc settling velocity and the floc diameter have a straight line relationship on a logarithm. The floc fractal dimension nf was 2.65 with increasing of initial concentration and 2.93 with increasing of NaCl. The exponent n to predict the settling velocity was proposed and varied from 1 to 1.93.
An Analysis of the Characteristics in Design Rainfall According to the Data Periods
Oh, Tae-Suk ; Kim, Min-Seok ; Moon, Young-Il ; Ahn, Jae-Hyun ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 115~127
Recently, Natural disasters are increasing the damage according to the influence of the abnormal climate and climate change. This study analyzed change characteristic of Design Rainfall according to the different data periods. First, 14 observatories were selected at Meteorological Administration. Second, frequency analysis carried out 5 cases by different data periods. At the results of the frequency analysis, the design rainfall could confirm the increase in most areas of Korea. Also, the change and trend analysis carried out for characteristic analysis by design rainfall and observed rainfall. The change and trend analysis of observed annual maximum rainfall did not appeared, but the change and trend analysis of design rainfall significantly appeared using statistic methods. The result of the change and trend analysis, design rainfall increased in most areas of Korea. Although, it could be the necessity for reestimating defense ability of flood, existing river systems, and new establishment of structure about the change characteristic.
Wash-off Characteristics of NPS Pollutants from Forest Landuse
Choi, Ji-Yeon ; Lee, So-Young ; Kim, Lee-Hyung ;
Journal of Korean Society of Hazard Mitigation, volume 9, issue 4, 2009, Pages 129~134
As a result of improved wastewater treatment facilities, the point source pollution emitted from human and municipal wastes is greatly decreasing. Conversely, the non-point source (NPS) pollution emanated from city streets, rural homes, suburban development, animal feedlot, croplands, and forestry is rapidly increasing. Practically, the main concern of the government is to control NPS pollutants by means of establishing a long term plan in order to protect the aqua-ecosystem. Studies have been conducted to assess the intensity of NPS from various landuses. In Korea, the data on NPS pollutant loadings are limited to few and broadly categorized landuses unlike in USA wherein specific landuses are available. This research aims to characterize the wash-off characteristics of NPS pollutants from forest landuse. Two sites were monitored during 15 storm events from 04/2008 to 10/2008. Mean
EMCs are 1.13 mg/L and 0.91 mg/L for the two sites, respectively. The results of this research will be a helpful contribution for the assessment of total NPS pollutant loadings.