• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.39 no.12
• /
• pp.547-552
• /
• 2002

In this paper, the path loss in domestic terrain environments for IMT-2000 are measured and considered. Domestic terrain environments are classified and received power is measured at 1.9201GHz. In addition, the Path loss is calculated with consideration of the radiation pattern of antennas based on the results of measurement. For the consideration of path loss in domestic terrain environments, each path loss are fitted with the same slope of a reference model as "COST-231 HATA Urban Model", and then both are compared. As a result, all of the path loss in domestic terrain environments are lower than the path loss of a reference model as "COST-231 HATA Urban Model". We found that a difference of path loss in domestic terrain environments and a reference model is 5dB in urban, 8dB in sparse urban, 12dll in dense suburban, 13dB in suburban, 19dB in sparse suburban, and 29dB in road.

• Geomechanics and Engineering
• /
• v.15 no.5
• /
• pp.1101-1111
• /
• 2018

This study aims to present accurate soil modeling and validation of a single roadside guardrail post as well as a single concrete pile installed near cut slopes or compacted sloping embankment. The conventional Winkler's elastic spring model and p-y curve approach for horizontal ground cannot directly be applied to sloping ground where ultimate soil resistance is significantly dependent on ground inclination. In this study, both grid-based 3-D FE model and particle-based SPH (smoothed particle hydrodynamics) model available in LS-DYNA have been adopted to predict the static behavior of a laterally loaded guardrail post. The SPH model has potential to eliminate any artificial soil stiffness due to the deterioration of the node-connected Lagrangian soil mesh. For this purpose, this study comprises two parts. Firstly, only 3-D FE modeling has been tested to show the numerical validity for a single concrete pile in sloping ground using Mohr-Coulomb material. However, this material option cannot be implemented for SPH elements. Nevertheless, Mohr-Coulomb model has been used since this material model requires six input soil data that can be obtained from the comparative papers in literatures. Secondly, this work is extended to compute the lateral resistance of a guardrail post located near the slope using the hybrid approach that combines Lagrange FE elements and SPH elements by the suitable node-merging option provided by LS-DYNA. For this analysis, the FHWA soil material developed for application to road-base soils has been used and also allows the application of SPH element.

• Journal of the Korean Geosynthetics Society
• /
• v.17 no.1
• /
• pp.95-109
• /
• 2018

Recently, GRS (Geosynthetic Retaining Segmental) wall has been widely used as a method to replace concrete retaining wall because of its excellent structural stability and economic efficiency. It has been variously applied for foundation, slope, road as well as retaining wall. The GRS wall system, however, has a weak point that is serious crack of wall due to stress concentration at curved part of it. In this study, therefore, behaviour of GRS wall according to shape of it, shich has convex and concave, are analysed and compared using Finite Element analysis as the fundamental study for design optimization. Results including lateral deflection, settlements of ground surface and wall obtained from 2D FE analysis are compared between straight and curved parts from 3D FE analysis.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.3D
• /
• pp.247-258
• /
• 2012

This research evaluates the serviceability of ZigBee device that provides a potential technology to realizing the ubiquitous computing by improving the productivity and effectiveness in construction and data acquisition. Literature review was conducted in various application areas such as bridge monitoring, slope management, road management, highway traffic control. In addition characteristics and challenges in various wireless technologies are described to identify their adoptability to construction environment. Among them, ZigBee technology was selected to introduce the functionality on hardware, network, and security. Then, questionnaire survey was implemented by four different group, construction engineers, students, hardware developers, and researchers to explore the success and failure factors of ZigBee technology in construction area. The results proposes a guideline of the applicability of ZigBee technology in the area of serviceability, application area, considerations, and future direction. This paper would provide valuable information for future researches and technology development in designing the wireless sensor network applications.

• The Journal of Engineering Geology
• /
• v.26 no.1
• /
• pp.23-32
• /
• 2016

This study evaluates landslide susceptibility using statistical analysis by SVM (support vector machine) and the illite index of clay minerals extracted from ASTER(advanced spaceborne thermal emission and reflection radiometer) imagery which can be use to create mineralogical mapping. Landslide locations in the study area were identified from aerial photographs and field surveys. A GIS spatial database was compiled containing topographic maps (slope, aspect, curvature, distance to stream, and distance to road), maps of soil properties (thickness, material, topography, and drainage), maps of timber properties (diameter, age, and density), and an ASTER satellite imagery (illite index). The landslide susceptibility map was constructed through factor correlation using SVM to analyze the spatial database. Comparison of area under the curve values showed that using the illite index model provided landslide susceptibility maps that were 76.46% accurate, which compared favorably with 74.09% accuracy achieved without them.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.14 no.1
• /
• pp.69-80
• /
• 1996

This Study aims at identifying optimum residential area of small and medium local cities to be relocated in the future. In the object of study, Chinju City was chosen and it consists of three stages of application to choose the priority of residential development us well as available residential locations. In the first stage, a digital image processing technique was applied to generate the existing urban land use information from the satellite image data. In the second stage, GIS technique was used to choose the avaliable residential area by evaluating the elements for residential site allocation such as road accessibility, topographic height, slope, aspect, legal limit, population density, and land price. In the third stage, some mathematical location models were applied to identify optimum candidates of residential areas chosen by earier stages. The results were evaluated by statistical methods and integer programming to identify the development priority. We expect this procedures and the results will be able to be used as a guide-line to support housing policies of Chinju City by allocating residential sites as well as a technique to apply a locational analysis for the future residential areas of small and medium local cities.

• Journal of the Korea Convergence Society
• /
• v.8 no.11
• /
• pp.177-182
• /
• 2017

The purpose of the study is to investigate the intravenous access of paramedics in ambulance. The study consisted of confidence change in pre and post intravenous access by driving condition and speed of the vehicle. The research subjects were 30 119 paramedics (20 level 1 emergency medical technicians, 10 nurses), and 6 ambulance driving conditions were established in order to measure the number of attempts at intravenous access. The data was collected for 9 days from May 18 through May 27, 2017. The results show no disparities in number of attempts in terms of stop conditions and flat section driving conditions(p=.161) although there were significant disparities in unpaved road(p=.003), speed bump(p=.005), curve(p=.022), and slope(p=.003) section driving conditions. Confidence appeared to significantly rise(p=.000) after the experiment. In conclusion, it is recommended that swift intravenous access inside an ambulance while driving is attempted when the vehicle has come to a stop or a flat section and paramedics should maintain their confidence in intravenous access through continued training.

• The Journal of Engineering Geology
• /
• v.30 no.1
• /
• pp.85-101
• /
• 2020

The estimation of strength parameters is very important for the stability analysis of rock slopes. Various methods for the determination of strength parameters were suggested by various researchers. The number of methods used for the estimation of strength parameters in the stability analysis of rock slopes were investigated based on literature reviews. The frequency of the method determining strength parameters were investigated with respect to failure types. The cohesion and friction angles of the rock and discontinuities are presented with RMR values. The cohesion shows wider range of values relative to those of friction angles according to current studies. Even though RMR does not show any correlation with cohesion values, RMR and the friction angle of the rock clearly shows a positive relationship. Proper methods should be utilized for the determination of strength parameters with consideration for failure types and be proved through literature reviews. The credibility of determining strength parameters is expected to improve if strength parameters data are accumulated from the back analysis performed for failed local rock slopes.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.11 no.3
• /
• pp.102-111
• /
• 2012

Expresway traffic accident is fatal accident by high speed, especially human injury is a great social issue. This paper aims to identify characteristic differences of highway accidents that involve human injuries or not. To analysis the elements that affect the two types of accidents used the logistic regression model. The analysis showed that human injury accident rate is increased in case of straight road, flat, or cut-slope areas, barriers, male driver, and older driver. These results provide the ground for actions to counter the problems. By discovering factors for accidents leading to fatality, this study can provide important implications for authorities that establish highway safety measures and policies in preventing human injuries or deaths from car accidents.

• Journal of Ecology and Environment
• /
• v.41 no.1
• /
• pp.1-8
• /
• 2017

Background: Though the biomass of floral vegetation in understory plant communities in a forested ecosystem only accounts for less than 1% of the total biomass of a forest, they contain most of the floral resources of a forest. The diversity of understory honey plants determines visitation rate of pollinators such as honey bee (Apis mellifera) as they provide rich food resources. Since the flower visitation and foraging activity of pollinators lead to the provision of pollination service, it also means the enhancement of plant-pollinator relationship. Therefore, an appropriate management scheme for understory vegetation is essential in order to conserve pollinator population that is decreasing due to habitat destruction and disease infection. This research examined the diversity of understory honey plant and studied how it is related to environmental variables such as (1) canopy density, (2) horizontal heterogeneity of canopy surface height, (3) slope gradient, and (4) distance from roads. Vegetation survey data of 39 plots of mixed forests in Chuncheon, Korea, were used, and possible management practices for understory vegetation were suggested. Results: This study found that 113 species among 141 species of honey plant of the forests were classified as understory vegetation. Also, the understory honey plant diversity is significantly positively correlated with distance from the nearest road and horizontal heterogeneity of canopy surface height and negatively correlated with canopy density. Conclusions: The diversity of understory honey plant vegetation is correlated to vegetation structure and human impact. In order to enhance the diversity of understory honey plant, management of density and height of canopy is necessary. This study suggests that improved diversity of canopy cover through thinning of overstory vegetation can increase the diversity of understory honey plant species.