• Atmosphere
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• v.25 no.3
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• pp.501-510
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• 2015

In this study, the characteristics of flows around building groups are investigated using a computational fluid dynamics (CFD) model. For this, building groups with different volumetric ratios in a fixed area are considered. As the volumetric ratio of the building group increases, the region affected by the building group is widened. However, the wind-speed reduced area rather decreases with the volumetric ratio near the ground bottom (z ${\lesssim}$ 0.7H, here, H is the height of the building group) and, above 0.7H, it increases. As the volumetric ratio decreases (that is, space between buildings was widened), the size of recirculation region decreases but flow recovery is delayed, resulting in the wider wind-speed reduced area. The increase in the volumetric ratio results in larger drag force on the flow above the roof level, consequently reducing wind speed above the roof level. However, above z ${\gtrsim}$ 1.7H, wind speed increases with the volumetric ratio for satisfying mass conservation, resultantly increasing turbulent kinetic energy there. Inside the building groups, wind speed decreased with the volumetric ratio and averaged wind speed is parameterized in terms of the volumetric ratio and background flow speed. The parameterization method is applied to producing averaged wind speed for 80 urban areas in 7 cities in Korea, showing relatively good performance.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.4
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• pp.58-64
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• 2020

Large-scale flooding due to extreme weather and typhoons causes heavy damage. This is especially true in urban areas where accumulated debris prevents the smooth drainage of rainwater in sewage facilities such as rain gutters installed near roads. In this study, to improve the drainage performance and effectively remove foreign substances by applying the dust screen used in rivers, the rain gutter with Coanda effect was simulated and compared with the experiment. The simulation was performed by setting the parameters to the fillet radius R₁ and R₂ at the top of the screen filter, the fillet radius R₃ at the bottom of the screen filter, and the height H of the gap W from the bottom. W is the gap at the backside of screen filter which is applied to stimulate the Coanda effect. According to the simulation results, the highest drain performance was 87.99% derived from R₁= 30mm, R₂= 5mm, R₃= 85mm, H= 75mm, and W= 2mm. The error rate of simulation results refer to the 4.89%~7.36% compared to the experimental results. In the future, by considering the slope according to the installation environment, the simulation results can be applied to the actual roadside to help prevent flood damage.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.110-115
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• 2010

Recently the deeply underground tunnels have been increased along the subway railroads of urban area compared to the past subway railroads. The Shin-Gum-Ho subway station (the Fifth lines, the depth : 46m) which is the third among the deep subway stations in the Korea was chosen as the model of deeply underground stations, and attempted to do simulation of fire. This station consists of three entrance, the basement first floor (B1), the basement second floor (B2), the basement eighth floor or platform (B8) and escalators and stairs from B2 to B8. The total number of grid was about 9,000,000 to make simulation of fire and smoke from the platform to entrance in this research, and the grid system was divided into 19 blocks to increase the efficiency of this simulation. The FDS (Fire Dynamics Simulation) was chosen to make the simulation of fire, and the model of turbulent flow was LES (Large Eddy Simulation). Each block is processed in a CPU using parallel processing of MPI (Message Passing Interface). The resource of CPU for this simulation is a ten of Intel 3.0 GHz Dual CPU (20 CPU).

• Journal of Family Resource Management and Policy Review
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• v.15 no.3
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• pp.131-151
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• 2011

This study attempted to estimate the level of perceived lack of time in Korean society, to link it to time management and to identify the possible association that accounts for time shortage. I employed the gender perspective in order to reveal the dynamics and complexity of the perception of a lack of time in the population. The sample for the study was drawn from the 1999 and 2009 Korean time diary data collected by the Korean National Statistical Office. From the original data, I selected a sample of second shift families(men and women who are presently working and raising children) living in metropolitan areas(including Seoul and six major urban areas in Korea). The dependent variable was time pressure measured by a single-item question on a four-point likert scale. The results of the study showed that working mothers perceived a greater time shortage as compared to working fathers. The time use pattern showed change during the periods, indicating that people worked fewer hours in paid labor and enjoyed more leisure hours and personal care hours. However, on average, people seemed to have experienced a greater time lack in 2009 as compared to 1999. The results from the ordered logistic regression model revealed that even though there were similarities in the impact of relevant factors, men's perception of a lack of time was more closely linked with their work role and social status, while for women, this perception was influenced by work and family duties. This indicates that Korean working mothers and fathers are facing a double jeopardy of time shortage in terms of combining their work and family roles. As a result, the level of time pressure by gender is converging toward a "never enough" phase. These findings generated policy implications and detailed suggestions.

• Structural Monitoring and Maintenance
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• v.1 no.1
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• pp.131-157
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• 2014

Special track systems used to divert a train to other directions or other tracks are generally called 'railway turnout'. A traditional turnout system consists of steel rails, switches, crossings, steel plates, fasteners, screw spikes, timber bearers, ballast and formation. The wheel rail contact over the crossing transfer zone has a dip-like shape and can often cause detrimental impact loads on the railway track and its components. The large impact also emits disturbing noises (either impact or ground-borne noise) to railway neighbors. In a brown-field railway track where an existing aged infrastructure requires renewal or maintenance, some physical constraints and construction complexities may dominate the choice of track forms or certain components. With the difficulty to seek for high-quality timbers with dimensional stability, a methodology to replace aged timber bearers in harsh dynamic environments is to adopt an alternative material that could mimic responses and characteristics of timber in both static and dynamic loading conditions. A critical review has suggested an application of an alternative material called fibre-reinforced foamed urethane (FFU). The full-scale capacity design makes use of its comparable engineering characteristics to timber, high-impact attenuation, high damping property, and a longer service life. A field trial to investigate in-situ behaviours of a turnout grillage system using an alternative material, 'fibre-reinforced foamed urethane (FFU)' bearers, has been carried out at a complex turnout junction under heavy mixed traffics at Hornsby, New South Wales, Australia. The turnout junction was renewed using the FFU bearers altogether with new special track components. Influences of the FFU bearers on track geometry (recorded by track inspection vehicle 'AK Car'), track settlement (based on survey data), track dynamics, and acoustic characteristics have been measured. Operational train pass-by measurements have been analysed to evaluate the effectiveness of the replacement methodology. Comparative studies show that the use of FFU bearers generates higher rail and sleeper accelerations but the damping capacity of the FFU help suppress vibration transferring onto other track components. The survey data analysis suggests a small vertical settlement and negligible lateral movement of the turnout system. The static and dynamic behaviours of FFU bearers appear to equate that of natural timber but its service life is superior.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.12
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• pp.5159-5164
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• 2016

Objective: The dynamics of morbidity, disability and death rates due to malignant neoplasms in the population in Uralsk city of the Republic of Kazakhstan were studied for 2011-2015, with a focus on age and sex, as well as tumor location. Methods: Statistics for total morbidity, primary disability and mortality from cancer in the adult population of the city of Uralsk for 2011-2015 were calculated per 100 thousand. Estimation of morbidity was based on data from form - $N{\underline{o}}12$ ${\ll}$Report on the number of diseases registered in patients living in the area of health care organizations and patient population under medical observation". Evaluation of primary disability was based on form $N{\underline{o}}7$ ${\ll}$The distribution of newly recognized disabled by disease class, age, sex and disability groups" for 2011-2015 in Ural city and analysis of cancer was carried out using annual form 7 "Report on the sick, and diseases of malignant neoplasms". Result: The most common localizations of cancer were the trachea, bronchi, lungs, stomach and mammary glands. High death rates were noted for patients with cancer of the trachea, bronchi, lung, as compared to stomach and esophagus. Conclusion: The results of our investigation and data in the literature indicate that regional characteristics influence the impact of risk factors associated with cancer. An unfavorable environmental background contributes to ill health of urban populations, contributing to development of cancer. Moreover behavioral risk factors are very important, such as smoking, alcohol drinking, and an unhealthy diet. All these factors require urgent adoption of a package of measures for prevention, early detection and timely treatment. Detailed study of cancer is necessary to develop national programs and activities for prevention and control.

• Journal of Navigation and Port Research
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• v.28 no.1
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• pp.105-111
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• 2004

This study is aiming at examining the possibilities to develop eco-friendly waterfront, and discusses characteristics of the organic worldview which has been emerged as new development or eco-friendly paradigm in recent science against the mechanical worldview of modem times. The orientation of waterfront development is characterized as unity, diversity, dynamics and mutuality. In addition, I examined the factors for waterfront design according to the locational, decorativeand visual properties of urban$.$architecture to find out concrete factors of its design. This study suggests the factors for waterfront design making use of organic properties, by examining the orientation for organic development of eco-friendly waterside environment and showing correlation between the factors of specific design, and their examples.

• Land and Housing Review
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• v.3 no.4
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• pp.451-456
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• 2012

In this study, a numerical analysis to evaluate the reduction of seismic load due to pile group was performed and compared the peak ground acceleration(PGA) measured at free-field and foundation. The special attention was given to the amplification of seismic acceleration on the foundation due to the pile effects. The analysis considering pile effects was carried out for 4, 8 and 12 piles with same condition by PLAXIS 2D Dynamics. Based on the analysis results, it is found that the overall reduction in seismic load due to foundation and reduction rates are similar irrespective of pile numbers. This study gives a possibility for effective design of piled foundation by reducing seismic load about 20~25%.

• Korean Journal of Ecology and Environment
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• v.44 no.1
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• pp.42-57
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• 2011

We described the above-ground plant species composition and measured a range of soil physico-chemical properties and the composition and size of the soil seed bank in the remnant natural vegetations on the flood plains of the Han River within Seoul, South Korea. We used analysis of variance and multivariate analyses to analyse the data and S${\o}$rensen's similarity index to compare the composition of the vegetation and seed banks. The soils were circum-neutral and composed of mainly sand and silt fractions with a very limited clay component; a gradient based on sand/clay proportions was identified. The soil seed banks varied markedly between- and within-sites and had much greater species diversity than the above-ground vegetation. Two of the major dominants in the vegetation (Miscanthus saccariflorus and Phragmites australis) were found at very low densities in the seed bank. The site differences appeared to be correlated with the sand-clay gradient, suggesting that the soil properties differentially affected seed inputs into the soil, or that the processes than controlled sediment deposition during floods was also important in differentially affecting seed deposition. Lastly, there was relatively little similarity between the vegetation, dominated mainly by perennials, and the seed bank which contained a relatively large proportion of annuals and biennials. This result suggests that after disturbance caused by flooding there is the potential for many other species to colonize. This may impinge on the regeneration potential of the sites and cause concern for the future conservation of these important remnants of natural vegetation.

• Fire Science and Engineering
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• v.30 no.5
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• pp.144-150
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• 2016

An apartment house with a pilotis that raises the architectural volume and provides a space for circulation is becoming popular. With the popularity of pilotis in apartment houses, people also have a keen interest in the potential fire risk at the pilotis. As residents can only access their apartment house through the pilotis, there is a risk to the occupants if there is fire there. Therefore, this study evaluated the pilotis fire cases of urban multifamily housing to conduct a Fire Dynamics Simulator (FDS) and Fire Evacuation Simulation (FES). Through these two simulation methods, it is possible to validate the riskiness of fire at an apartment with a pilotis. The study identified that the toxic gases and flame spread out to the pilotis within hundred seconds after ignition. In addition, the toxic gases and flame also reach the second floor within three seconds and the entire building within 735 seconds if the entrance doors at the pilotis are opened. On the other hand, the FES simulation results showed that it also takes about approximately 609 seconds to excavate from the apartment house with a pilotis. Therefore, this research shows that an apartment house with a pilotis can ensure the building occupants' lives and their safety if there is fire.