• Journal of the Korean Society for Railway
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• v.14 no.3
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• pp.262-270
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• 2011

Track support stiffness which affected track maintenance and riding comfort had a big effect on the track and train. Also, track support stiffness of the track design which was based on theory differs from track support stiffness of the track generated on the field. Track support stiffness was generated by several factors such as dynamic wheel loads, vertical displacement of track, and stress at rail bottom on the field test. With the results of the field test was compared with theoretical value. This paper analyzed that track support stiffness of ballast depended on condition of ballast, and support stiffness of concrete track also depended on the characteristic of track structures such as, normal elastic fastening system, rail floating system and sleeper floating system. However, on the ballast and concrete track, the designed track support stiffness was underestimated less than the measured track support stiffness. When the track condition was estimated on service line, it would not consider the track condition on the field. Therefore, this study proposed the various track type and the range of track support stiffness based on the experimental test.

• Journal of Korean Society on Water Environment
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• v.31 no.1
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• pp.12-18
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• 2015

In this research, the hydrologic effects between a pre-existing urban landuse and low impact development (LID) applied conditions were compared and evaluated. The infiltration trench and tree box filter that were utilized in LID represent only 1% of the catchment area that they drain. Storm event monitoring were conducted from July 2010 to July 2014 on a total of 22 storm events in both LID sites. After LID, hydrological improvement was observed as the sites exhibited a delay (lag time) or reduction in the magnitude, frequency and duration of runoff and flow peaks as the rainfall progress. In addition, the maximum irreducible peak flow reduction for infiltration trench was found to be 61% and 33% for the tree box filter when rainfall was 40 mm and 30 mm, respectively. In designing LID, it is recommended to consider the storage capacity and catchment area, as well as the amount of rainfall and runoff on the site.

• Journal of Korean Society of Steel Construction
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• v.26 no.2
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• pp.119-132
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• 2014

In this paper, a series of numerical analyses were performed to evaluate the flexural resistance of steel plate girder with longitudinally stiffened and slender web. The SM490 steel was adopted for the study and the flexural resistances evaluated from the numerical analysis were compared with those suggested by the AASHTO LRFD and the Eurocode 3 codes, respectively. It was found that the AASHTO LRFD code could considerably underestimate the flexural resistance as the web slenderness becomes smaller. This comes from the fact that current AASHTO LRFD code does not consider a possible increase of slenderness limits for compact and noncompct web, and also an additional effect of web restraint on the rotation of compression flange in longitudinally stiffened web. Therefore, the slenderness limits of web and flange have been newly proposed for the plate girders with longitudinally stiffened web and it is analytically verified that the flexural resistance can be appropriately estimated by applying the proposed slenderness limits to the AASHTO LRFD code.

• Korean Journal of Social Welfare
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• v.65 no.3
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• pp.29-52
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• 2013

This study examined how middle-aged and elderly persons allocated their time in overall perspective and whether the patterns were varied by age, socio-demographic factors, and the interaction effect between them. This study analyzed the 2009 Time Use Survey Data (17,096 time-diaries of people aged 45 or more) of the National Statistical Office using tobit regression model. The main results are as follows. First, middle-aged and elderly people gradually decreased paid work times. Second, the patterns of time allocation were varied by age, gender, education level, marital status and household type(Agricultural/non-agricultural). Third, there were interaction effects between age and the socio-demographic factors on paid work time and leisure time. Highly educated or urban persons were likely to have less time in paid work less than other groups with increasing age. And females were likely to have less time in domestic labor and care work than males with increasing age. But they had more time in social and economic productive activities than males. Based on these findings, this study suggests comprehensive approach to analyze the time use of elderly beyond economic working time or leisure time. To establish effective ageing society policy, it is necessary to consider the time allocation of elderly which divided into the social stratification.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.273-279
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• 2003

The purpose of this study is to clarify the effect of the monomer ratio on properties of the polymer-modified mortars using methylmethacrylate-butyl acrylate(MMA/BA) latexes, and to obtain basic data necessary to develop appropriate latexes for cement modifiers. From the test results, we knew that the pore volume of polymer-modified mortars using MMA/BA latexes at bound MMA contents of 60 and 70 percent is 7.5∼75nm and the fine pore volume is increased with an increase in the polymer-cement ratio. The total pore volume of polymer-modified mortars using MMA/BA latexes is linearly reduced with an increase in the bound MMA content and increased in the polymer-cement ratio. In general, the superior compressive strength of polymer-modified mortars using MMA/BA latexes is obtained at a bound MMA content of 70 percent and a polymer-cement ratio of 15%. And, the water absorption and chloride ion penetration depth are greatly affected by the polymer-cement ratio rather than the bound MMA content. The important factors affecting the properties of polymer-modified mortars using MMA/BA latexes polymerized with various monomer ratios are the variations of the pore size distribution with changing bound MMA content and the polymer-cement ratio.

• Journal of Environmental Policy
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• v.10 no.1
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• pp.27-47
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• 2011

Used as foundation resources for environment improvement and preservation of single-housing residential area by practicing classification of biotope with the concept of ecological area rate applied and performing urban thermal environment prediction simulation. Biotope is classified as seven types according to classification of biotope which is carried out with the concept of ecological area rate applied. The classification is listed below in descending order: building biotope(48.16%), impervious pavement biotope(39.75%), greenspace biotope(6.23%), crack permeable pavement biotope(3.26%), whole surface permeable pavement biotope(2.51%), parts permeable pavement biotope(0.04%). As a result of analysing prediction of variation and characteristics of thermal environment of single-housing residential area, land surface temperature per types of biotope are evaluated as listed below in descending temperature order: impervious pavement biotope > building biotope > greenspace biotope > permeable pavement biotope. In case 2 where vegetated roof hypothetically covers 100% of the roof area, temperature is predicted to be $33.58^{\circ}C$ Max, $23.85^{\circ}C$ Min, and $27.74^{\circ}C$ Avg. which is Approximately $5.19^{\circ}C$ lower than a non-vegetated roof. Average outdoor temperature for case 2 is studied to be $0.18^{\circ}C$ lower than case 1.

• Journal of Environmental Science International
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• v.19 no.3
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• pp.295-304
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• 2010

Actual evapotranspiration (AET) in the Suyeong-gu was estimated and correlations between AET and meteorological factors were analyzed. The study area was Suyeong-gu lay at the east longitude $129^{\circ}$ 05' 40" ~ 129$^{\circ}$ 08' 08" and north latitude $35^{\circ}$ 07' 59" ~ $35^{\circ}$ 11' 01". The Kumryun mountain, the Bae mountain, the Suyeong river and the Suyeong bay are located on west, north, northeaster and south side in the study area, respectively. AET was estimated using precipitation (P), potential evapotranspiration (PET) and plant-available water coefficient. Meteorological factors to estimate PET were air temperature, dewpoint temperature, atmospheric pressure, duration of sunshine and mean wind speed (MWS). PET and AET were estimated by a method of Allen et al. (1998) and Zhang et al. (2001), respectively. PET was the highest value (564.45 mm/yr) in 2002 year, while it was the lowest value (449.95 mm/yr) in 2003 year. AET was estimated highest value (554.14 mm/yr) in 2002 year and lowest value (427.91 mm/yr) in 2003 year. Variations of PET and AET were similar. The linear regression function of AET as PET using monthly data was AET=0.87$\times$PET+3.52 and coefficient of determination was high, 0.75. In order to analyze relationship between the evapotranspiration and meteorological factors, correlation analysis using monthly data were accomplished. Correlation coefficient of AET-PET was 0.96 high, but they of AET-P and PET-P were very low. Correlation coefficients of AET-MWS and PET-MWS were 0.67 and 0.73, respectively. Thus, correlation between evapotranspiration and MWS was the highest among meteorological factors in Suyong-gu. This means that meteorological factor to powerfully effect for the variation of evapotranspiration was MWS. The linear regression function of AET as MWS was AET=84.73$\times$MWS+223.05 and coefficient of determination was 0.54. The linear regression function of PET as MWS was PET=83.83$\times$MWS+203.62 and coefficient of determination was 0.45.

• Journal of Navigation and Port Research
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• v.31 no.5 s.121
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• pp.409-414
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• 2007

The effect of multipath is especially serious in urban area and sea surface where buildings and water reflect GPS signal. Multipath brings about the performance degradation on many GPS application because the presence of multipath causes the diminution of pseudorange measurement accuracy in turn position accuracy. In this paper, a multipath mitigation named weighted correlation method is implemented on software GPS receiver, in which the asymmetric correlation function is compensated by modifying the late correlation value. Asymmetry compensation is obtained as weighted sum of two correlators which have different early-late chip spaces. This structure is adopted to lessen the computation load lower keeping up performance similar to that. The performance of implemented multipath mitigation technique is evaluated using GPS signal and multipath signal generated by GPS signal generator and software GPS receiver. The test results show that the weighted correlation method gives hefter performance than the standard correlator and the narrow correlator.

• Land and Housing Review
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• v.7 no.4
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• pp.225-237
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• 2016

This study is to investigate actual condition of passenger terminals, public facilities which are used by unspecified individuals, with high spread effect of certification system of Barrier Free introduced in 2007, evaluate possibility of the certification and prepare an effective way for certification in order to spread and settle the certification system. According to the investigation on the facilities' equipment level of 349 passenger terminals, which being nationally operated, 217 terminals could be certified and non-certified were 58. And, 29 was evaluated as the passenger terminals with high possibility to get Barrier Free certification by small scale of remodeling. The level of Barrier Free of investigated passenger terminals, according to the actual condition with certification index, were 40~55 percent. While the level of Barrier Free of internal facilities of the terminals was over 90percent, the level of sanitary facilities, information facilities, etc. fell short of 50 percents. In this study, pilot project of Barrier Free certification is proposed for enhance of passenger terminal facilities. Moreover, the selection of passenger terminals with high possibility of certification, local governments' strong will as the targets of pilot project for improvement of amenity level and Barrier Free certification and monitoring the project results are the way of the project.

• Resources Recycling
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• v.25 no.2
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• pp.17-24
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• 2016

This study aims at evaluating environmental impacts on recycling process of used small household appliances. The recycling process mainly consists of manual dismantling, crushing and various sorting processes to effectively recover valuable resources and to minimize environmental impact. In this study, life-cycle assessment (LCA) methodology is applied to analyze major environmental parameters such as GWP, ADP, POCP, EP, etc. One of the major impact categories on the weight basis in the recycling process is global warming (GWP) 57.1%, next to ADP 35.4% and POCP 4.8%, respectively. As a result of environmental impact on recovery of valuable resources/ton, the GWP of plastics for ABS is highest (33.7%) compared to ferrous metals (9.4%). The effects of environmental and economical benefit are also analyzed to compare with the amount of virgin materials to be recycled by recycled materials. In addition, recycled materials are also more economical in comparison to virgin materials due to the environmental avoiding effect by recycling. In conclusion, the key environmental issues related to the recycling of e-wastes are analyzed and therefore, the effective recycling process will contribute to mitigate global warming potential in the near future.