• Journal of the Korea Concrete Institute
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• v.18 no.3 s.93
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• pp.425-429
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• 2006

Horizontal cracks at the mid-depth of concrete slabs were observed at a section of the continuously reinforced concrete pavement(CRCP) structures on the Korea Highway Corporation's Test Road. To investigate the existence and the extent of horizontal cracks in the concrete slab, a number of cores were taken from the section of CRCP. To identify the causes of horizontal cracks, numerical analyses were conducted. Several variables relative to design, material, and environment were considered in the studies to evaluate possible causes of horizontal cracking. A numerical model of CRCP was developed using the finite element discretization, and the shear and normal tensile stress distributions in CRCP were investigated with the model. Numerical analysis results show that the maximum shear and normal tensile stresses develop near the depth of steel bars at transverse cracks. If those maximum stresses reach the strength of concrete, horizontal cracks occur. The maximum stresses become higher as the environmental loads, coefficient of thermal expansion of concrete, and elastic modulus of concrete increase.

• International Journal of Highway Engineering
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• v.16 no.6
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• pp.95-104
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• 2014

PURPOSES : The purpose of this study is to evaluate the degree of restraint (DOR) of longitudinal steel at continuously reinforced concrete pavement (CRCP) against environmental loadings. METHODS : To measure the longitudinal steel strain, 3-electrical resistance and self-temperature compensation gauges were installed to CRCP test section (thickness = 250mm, steel ratio = 0.7%) and continuously measured 10 min. intervals during 259 days. In order to properly analyze the steel strains first, temperature compensation process has been conducted. Secondly, measured steel strains were divided into 12 phases with different events such as before paving, during concrete hardening, and after first cracking, etc. RESULTS : Thermal strain rate (TSR) concept is defined as the linear strain variations with temperature changes and restraints rate of longitudinal steel against environmental loadings (especially thermal loading) with different cases is defined as degree of restraint(DOR). New concept of DOR could be indirect indicator of crack width behaviors of CRCP. CONCLUSIONS : Before paving, DOR of longitudinal steel is almost same at the coefficient of thermal expansion of steel ($12.44m/m/^{\circ}C$) because of no restraint boundary condition. After concrete pouring, DOR is gradually changed into -1 due to concrete stiffness developing with hydration. After first cracking at crack induced area, values of DOR are around -3~-5. The negative DOR stands for the crack width behavior instead of steel strain behavior. During winter season, DOR reached to -5.77 as the highest, but spring this values gradually reduced as -1.7 as the lowest. Based on this observation, we can presume crack width decreased over time within the time frame of this study. This finding is not consistent with the current theory on crack width variations over time, so further study is necessary to identify the causes of crack width reducing. One of the reasons could be related to concrete stress re-distribution and stress relaxation.

• International Journal of Highway Engineering
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• v.16 no.6
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• pp.59-67
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• 2014

PURPOSES : The purpose of this study is to analyse the longitudinal steel strain and stress of continuously reinforced concrete pavement(CRCP) with longitudinal and transverse direction at early age using stress dependent strain analysis method. METHODS : To measure the longitudinal steel strain, 9-electrical resistance and self-temperature compensation gauges were installed to CRCP test section (thickness = 250mm, steel ratio = 0.7%) and continuously measured 10min. intervals during 30days. In order to properly analyze the steel stress first, temperature compensation process has been conducted. Secondly, measured steel strains were divided into stress dependent strain (elastic strain) and stress independent strain (thermal strain) and then stress dependent strain was applied to stress calculation of longitudinal steels. RESULTS : Steel strains were successfully measured during 30days. To verify the accuracy of temperature compensation process, measured coefficient of thermal expansion(COTE,$11.46{\times}10^{-6}m/m/^{\circ}C$) of longitudinal steel before paving was compared with that of unrestrained steel. Max. steel stress in the transverse direction shows about 266MPa at 23days after placement. CONCLUSIONS : Steel stresses in the longitudinal and transverse direction have been evaluated. In longitudinal direction, steel stress from the crack was rapidly reduced from 183MPa at crack to 18MPa from 600mm apart the crack. From this observation, stress effective length can be identified as within 600mm apart from the crack. In transverse direction, max. stress point was located near the center of pavement width and stress level(266MPa) is about 66% of yield stress of steel.

• International Journal of Highway Engineering
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• v.19 no.1
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• pp.45-52
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• 2017

PURPOSES : The main purpose of this study is to develop a high elastic modulus and low-shrinkage roller-compacted concrete base (RCCB) in order to prevent fatigue cracking and reflective cracking in the asphalt surface layer of composite pavement. Using a rigid base material with low shrinkage can be a solution to this problem. Moreover, a strong rigid base with high elastic modulus is able to shift the location of critical tensile strain from the bottom of the asphalt layer to the bottom of the rigid base layer, which can prevent fatigue cracking in the asphalt layer. METHODS : Sensitivity analysis of composite pavement via numerical methods is implemented to determine an appropriate range of elastic modulus of the rigid base that would eliminate fatigue cracking. Various asphalt thicknesses and elastic moduli of the rigid base are used in the analysis to study their respective influences on fatigue cracking. Low-shrinkage RCC mixture, as determined via laboratory testing with various amounts of a CSA expansion agent (0%, 7%, and 10%), is found to achieve an appropriate low-shrinkage level. Shrinkage of RCC is measured according to KS F 2424. RESULTS : This study shows that composite pavements comprising asphalt thicknesses of (h1) 2 in. with E2 > 19 GPa, 4 in. with E2 > 15 GPa, and 6 in. with E2 > 11 GPa are able to eliminate tensile strain in the asphalt layer, which is the cause of fatigue cracking in this layer. Shrinkage test results demonstrate that a 10% CSA RCC mixture can reduce shrinkage by 84% and 93% as compared to conventional RCC and PCC, respectively. CONCLUSIONS : According to the results of numerical analyses using various design inputs, composite pavements are shown to be able to eliminate fatigue cracking in composite pavement. Additionally, an RCC mixture with 10% CSA admixture is able to reduce or eliminate reflective cracking in asphalt surfaces as a result of the significant shrinkage reduction in the RCC base. Thus, this low-shrinkage base material can be used as an alternative solution to distresses in composite pavement.

• Journal of Korean Society of Transportation
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• v.21 no.6
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• pp.77-88
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• 2003

This paper proposes a solution algorithm for solving a multi-class analytical DTA model. In the DTA model, three traveler classes are classified according to different assumptions of traveler's route choice behavior: including fixed route, Stochastic Dynamic User Optimum(SDUO), and Dynamic User Optimum(DUO). To solve this DTA model, variables of link flow and exit flow are represented solely by inflow. The resulting Linear Program(LP) subproblem in the inner iteration is solved as a typical time-dependent shortest route problem over a physical network. Accordingly, the required time-space network expansion in solving DTA models is no longer needed.

• Journal of Distribution Science
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• v.14 no.10
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• pp.59-72
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• 2016

Purpose - This study expands the corporate social responsibility (CSR) model and concepts by adding to it the concepts of corporate identity and public existence responsibility. Then, this study examines the structural relationship between corporate identity and public existence responsibility. This study contributes to expanding CSR to give customers a different perspective from previous studies in that it specifically measures corporate public existence responsibility, corporate identity, and corporate value creation and investigates the structural relationship. Research design, data, and methodology - This study addresses specific research questions. First, it asks whether non-financial performance is a component of CSR; second, it asks if the improvement in the corporate image should be treated as its corporate identity; and third, it tries to expand CSR concepts from corporate citizenship and public market awareness to public existence responsibility. The research hypothesis is formulated to confirm the relationships among CSR, corporate value creation, corporate identity, and public existence responsibility. Result - This study confirms that CSR has a positive correlation with corporate value creation and that CSR has a relatively positive correlation with corporate identity and public existence responsibility. Additionally, it confirms a positive correlation between corporate identity and public existence responsibility. However, corporate identity and public existence responsibility do not have an effect on corporate value creation. However, the influence of public existence responsibility confirmed the influence of corporate value creation through corporate identity as a mediating variable. Conclusion - This study argues that CSR produces more general performance including both financial and non-financial performance. It also confirms that the goals and performance of CSR can substitute for corporate value creation from general performance. It further confirms that public existence responsibility includes market public awareness, corporate images, and corporate associations. It suggests that corporations should see themselves as having public existence responsibility. Further, they should devise strategies to build corporate identities that associate with corporate goals and visions. Finally, this study contributes to the expansion of perspectives on CSR theoretical concepts and goals of performance of the corporation throughout the corporate value creation process.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.15 no.2
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• pp.141-148
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• 1997

Continuous development of Personal Computer(PC) combined with the decrease of price and the expansion of operating system in PC like Windows 95, and Windows N/T makes it possible for the user to consider PC-bas-ed Automated Happing/Facilities Management (AM/FM) system. Therefore, the purpose of this study is to establish a PC-based data automation system of pipe infrastructures-water, sewer, and drainage-and road in Korea Land Corporation. In order to achieve this goal, relevant literature survey was done first. Secondly, the study site was determined by discussion with Korea Land Institute. Thirdly, PC-based CAD software for AM/FM in the world market were surveyed, and AutoCAD Map was selected because KLC had been using hundreds of AutoCAD copies already. After that user needs assessment was done to visit on-site office, local branch office, and the corresponding city office for the system design and database design. After the graphic data were digitized and the attribute data were entered into the batabase, the data automation system was established, and tested for application. Finally, the guidelines and problems for PC-based data automation in AM/FM was discussed.

• International Journal of Highway Engineering
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• v.14 no.1
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• pp.17-24
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• 2012

This study evaluated the performance of Korean epoxy asphalt mixtures using several laboratory tests. Four types of epoxy asphalt mixtures were manufactured based on 13mm dense graded asphalt mixtures: three Korean and one Japanese epoxy asphalt mixtures where 20% or 40% of asphalt binder was replaced by epoxy resins. Curing time was determined as 3 and 6 hours for the mixtures containing 40% and 20% of epoxy resins, respectively. From the laboratory tests including wheel tracking, indirect tension fatigue, bending beam, and moisture susceptibility tests, it was concluded that the epoxy asphalt mixtures had superior performance than conventional asphalt mixtures except moisture susceptibility. Also, the performance of the Korean epoxy asphalt mixtures was comparable to the Japanese mixtures. Thermal coefficient, bond strength, and indirect tension tests were conducted to examine the applicability of the Korean epoxy asphalt mixtures to concrete repair. Its adhesion was strong enough to be bonded to surrounding concrete materials and its tensile strength was comparable to the concrete, but thermal expansion coefficient was 5 times greater than the surrounding concrete.

• Tunnel and Underground Space
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• v.23 no.2
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• pp.87-98
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• 2013

Around 70% of Korea is mountainous, an increase in tunnel construction. It's due to the growing interest of the public for the environment and land required for the road construction is very scarce. During construction of 'Daedong 1 tunnel' in the expressway expansion project between Naengjeong and Busan, there are shallow shaft due to this tunnel located in the valley and the shafts are separated, and penetrating location change was inevitable for construction was delayed because of complaint. So, we change the position of the penetrating by applying multi-channel TSP, and conducted a stability analysis. The analysis results showed that there is no problem on the stability of the tunnel. To secure the construction of additional stability, We installed instrument, performed mechanical excavation, added reinforcement at shallow shaft and conducted bench cut.

• Korean Journal of Veterinary Service
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• v.35 no.1
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• pp.33-37
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• 2012

As people's interest about wildlife animal increases, more wildlife animal centers are developing. In South Korea, currently 120 mammal species live, and 22 of them are designated as endangered species. It is important to protect these natural treasures and endangered species, because they are being harmed by human industrial activity. For example, road expansion and poaching have led to the destruction of wildlife animal habitats, which is increasing year by year. Nevertheless, data regarding the systematic treatment of wild animals that are in distress is lacking, and it is a reality that analysis of such data is also lacking. The Kangwon Wildlife Rescue Center investigates these types of distress experienced by mammals. By analyzing the shape of the wild animals killed or injured, the center seeks an efficient and systematic way to manage such distress. The data collected from the Wildlife Animal Center from September 2007 to August 2010 includes 195 different cases, and the animals point of rescue. There are 16 species, including 87 water deer (Hydropotes inermis), 39 raccoons (Nyctereutes procyonoides), 20 roe deer (Capreolus pygargus bedfordi), 10 goral (Nemorhaedus goral), 7 siberian weasels (Mustela sibirica), 6 otters (Lutra lutra) and etc. Within the first year (September 2007 to August 2008), the number of mammals rescued was 46. In the second year (September 2008 to August 2009), 60 animals were rescued. in the third year (September 2009 to August 2010), the Wildlife Animal Center had 89 animals. We can see that these numbers are increasing, which shows that people are interested in the well-being of these animals because they are reporting animal injuries more and more. The mains form of distress caused by humans are from car accidents 67 (34.4%). Traps, and other hunting tools used by poachers are responsible for 25 (13.0%). Also, human industrial activity thus indirectly led to the starvation 25 (13.0%). and the orphaning of young animals 37 (19.0%).