• Journal of the Korean Geotechnical Society
• /
• v.31 no.7
• /
• pp.29-39
• /
• 2015

The vertical load imposed on the bucket foundation is transferred from the soil inside the bucket to the bottom of the foundation, and also to the outer surface of the skirt. For the design of a bucket foundation installed in sand, the vertical load transfer characteristics have to be clearly identified. However, the response of bucket foundations in sand subjected to a vertical load has not been investigated. In this study, we performed two-dimensional axisymmetric finite element analyses and investigated the vertical load transfer mechanism of bucket foundation installed in sand. The end bearing capacity of bucket foundation is shown to be larger than that of the shallow foundation, whereas the frictional resistance is smaller than that for a pile. The end bearing capacity of the bucket foundation is larger than the shallow foundation because the shear stress acting on the skirt pushes down and enlarges the failure surface. The skin friction is smaller than the pile because the settlement induces horizontal movement of the soil below the tip of the foundation and reduces the normal stress acting at the bottom part of the skirt. The calculated bearing capacity of the bucket foundation is larger than the sum of end bearing capacity of shallow foundation and skin friction of pile. This is because the increment of the end bearing capacity is larger than the reduction in the skin friction.

• Journal of the Korean earth science society
• /
• v.36 no.4
• /
• pp.315-329
• /
• 2015

We investigated the characteristics of meteorological conditions related to the strong downslope wind over the leeward side of the Taebaek Mountains during the period 2005~2010. The days showing the strong wind exceeding $14ms^{-1}$ in Gangwon province were selected as study cases. A total of 15 days of strong wind were observed at Sokcho, Gangneung, Donghae, and Taebaek located over the Yeongdong region. Seven cases related to tropical cyclone (3 cases) and heavy snowfall (2 cases) and heavy rainfall (2 cases) over the Yeongdong region were excluded. To investigate the characteristics of the remaining 8 cases, we used synoptic weather chart, Sokcho radiosonde, Gangneung wind profiler and numerical model. The cases showed no precipitation (or ${\leq}1mm\;day^{-1}$). From the surface and upper level weather chart, we found the pressure distribution of southern high and northern low pattern over the Korean peninsula and warm ridge over the Yeongdong region. Inversion layer (or stable layer) and warm ridge with strong wind were located in about 1~3 km (925~700 hPa) over mountains. The Regional Data Assimilation and Prediction System (RDAPS) indicated that warm core and temperature ridge with horizontal temperature gradient were $0.10{\sim}0.23^{\circ}C\;km^{-1}$ which were located on 850 hPa pressure level above mountaintop. These results were summarized as a forecasting guidance of downslope windstorm in the Yeongdong region.

• Journal of the Korean earth science society
• /
• v.36 no.3
• /
• pp.280-299
• /
• 2015

The purpose of this study was to investigate the effects of an instruction using geologic planar figures on high school students' ability of spatial visualization and geologic spatial ability and also to explore its applicability as an instructional strategy through the investigation of students' perception about the instruction using mixed methodology. For this purpose, we developed 10 planar figures of geologic structures (2 horizontal layers, 2 vertical layers, 4 angular layers, 1 fault, and 1 fold), and tested students' spatial visualization ability and geologic spatial ability before and after the implementation in class. In addition, in order to investigate students' perception on the instruction, we conducted quantitative research using questionnaires comprised of the cognitive and the affective domain, and followed by focus group interview that was conducted to obtain deeper understanding of their perception. Findings revealed that the instruction using geologic planar figures was effective to enhance spatial visualization ability and geologic spatial ability. It was also helpful for students to enhance their ability to perceive the spatial configuration of the geologic structures as well as the ability to penetrate visually into the images of the structures. The results of the students' perception on the instruction showed that the students recognized the instruction using geologic planar figures as a strongly positive teaching method both in the cognitive and affective domain. We concluded that geologic planar figures could be used as an effective tool for the lesson of 'mapping and interpreting of geological map', and be highly applicable for the advanced class in high schools.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.9
• /
• pp.3295-3305
• /
• 2011

Thermal behavior of poly (methyl methacrylate) was analyzed in the presence of tin (IV) chloride. Five different proportions - polymer to additive - were selected for casting films from common solvent. TG, DTG and DTA were employed to monitor thermal degradation of the systems. IR and py-GC-MS helped identify the decomposition products. The blends start degrading at a temperature lower than that of the neat polymer and higher than that of the pure additive. Complex formation between tin of additive and carbonyl oxygen (pendent groups of MMA units) was noticed in the films soon after the mixing of the components in the blends. The samples were also heated at three different temperatures to determine the composition of residues left after the expulsion of volatiles. The polymer, blends and additive exhibited a one step, two-step and three-step degradation, respectively. $T_0$ is highest for the polymer, lowest for the additive and is either $60^{\circ}C$ or $70^{\circ}C$ for the blends. The amount of residue increases down the series [moving from blend-1 (minimum additive concentration) to blend-5 (maximum additive concentration)]. For blend-1, it is 7% of the original mass whereas it is 16% for blend-5. $T_{max}$ also goes up as the concentration of additive in the blends is elevated. The complexation appears to be the cause of observed stabilization. Some new products of degradation were noted apart from those reported earlier. These included methanol, isobutyric acid, acid chloride, etc. Molecular-level mixing of the constituents and "positioning effect" of the additive may have brought about the formation of new compounds. Routes are proposed for the appearance of these substances. Horizontal burning tests were also conducted on polymer and blends and the results are discussed. Activation energies and reaction orders were calculated. Activation energy is highest for the polymer, i.e., 138.9 Kcal/mol while the range for blends is from 51 to 39 Kcal/mol. Stability zones are highlighted for the blends. The interaction between the blended parts seems to be chemical in nature.

• Journal of the Economic Geographical Society of Korea
• /
• v.15 no.4
• /
• pp.642-659
• /
• 2012

The main aim of this article is to examine theoretical issues on the 'global-local connectivity' of regional industrial cluster and regional innovation system which have been presented since the 2000s in terms of three different aspects. Firstly, the concept of 'geographical proximity' is discussed within the context of its importance for the regional industrial development by considering relationships of cluster, local buzz and global pipeline. Secondly, concepts on knowledge gatekeeper and temporary cluster are explored with respect to their role of a mediator in forming or transforming global-local connectivity. Finally, policy implications of the global-local connection are presented. Authors arguments are as follows; firstly, in order to improve regional industrial cluster on the basis of geographical proximity, relational proximity which is beyond different spatial scales has to be secured. It means that geographical convenience and inconvenience are required simultaneously for regional industrial development. Secondly, A base of the global-local connectivity is socal capital and embeddedness. Therefore, it needs to understand that relational proximity is embedded into different culture and habit at different spatial scales. Finally, within the context of the global-local connectivity, in order to overcome spatial hierarchy by the division of labor of firms, it needs to consider the complex system which is composed of vertical and horizontal hierarchy by the spatial division of labor by firms, openness and closeness of clusters, and the scope of policies' inclusion and exclusion by central and local governments.

• Korean Journal of Plant Resources
• /
• v.30 no.5
• /
• pp.481-488
• /
• 2017

Under circumstances of rapid disappearing of traditional ethnobotanical knowledge, traditional ethnobotanical knowledge surveys are the major step in documenting useful species with a conservation priority. In the ethnobotanical research, the relevance to the survey intensity, ethnobotanical information and plant species richness is the most important research theme. We made up TEK database in south Korea using metadata which had been published by the Korea National Arboretum. We calculated species richness using species richness estimator like ACE, Chao1, Chao2, ICE, Jack 1, Jack 2, and Bootstrap. Species accumulation curves showed each province sampling efforts appeared to be wide range of variance so that Gangwon province need more sampling efforts, and Chungnam province approached a horizontal asymptote earlier. We found heterogeneous patterns in the rarefaction curves of TEK species between gender for each categories of use (medicinal, food and handicrafts). Comparing with regional floral diversities, it was predicted that more diverse species would be found in some provinces by carrying out additional survey.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.315-315
• /
• 2017

In Japan, more than 80 % of soybean growing area is converted fields and excess water is one of the major problems in soybean production. For example, recent study (Yoshifuji et al., 2016) suggested that in the fields of shallow groundwater level (GWL) (< 1m depth), rising GWL even in a short period (e.g. 1 day) causes inhibition of soybean growth. Thus it becomes more and more important to predict GWL and soil moisture in detail. In addition to conventional surface drainage and underdrain, FOEAS (Farm Oriented Enhancing Aquatic System), which is expected to control GWL in fields adequately, has been developed recently. In this study we attempted to predict GWL and soil moisture condition at the converted field with FOEAS in Biwa lake reclamation area, Shiga prefecture, near the center of the main island of Japan. Two dimensional HYDRUS model (Simuinek et al., 1999) based on common Richards' equation, was used for the calculation of soil water movement. The calculation domain was considered to be 10 and 5 meter in horizontal and vertical direction, respectively, with two layers, i.e. 20cm-thick of plowed layer and underlying subsoil layer. The center of main underdrain (10 cm in diameter) was assumed to be 5 meter from the both ends of the domain and 10-60cm depth from the surface in accordance with the field experiment. The hydraulic parameters of the soil was estimated with the digital soil map in "Soil information web viewer" and Agricultural soil-profile physical properties database, Japan (SolphyJ) (Kato and Nishimura, 2016). Hourly rainfall depth and daily potential evapo-transpiration rate data were given as the upper boundary condition (B.C.). For the bottom B.C., constant upward flux, which meant the inflow flux to the field from outside, was given. Seepage face condition was employed for the surrounding of the underdrain. Initial condition was employed as GWL=60cm. Then we compared the simulated and observed results of volumetric water content at depth of 15cm and GWL. While the model described the variation of GWL well, it tended to overestimate the soil moisture through the growing period. Judging from the field condition, and observed data of soil moisture and GWL, consideration of soil structure (e.g. cracks and clods) in determination of soil hydraulic parameters at the plowed layer may improve the simulation results of soil moisture.

• Journal of the Korea Concrete Institute
• /
• v.29 no.2
• /
• pp.209-216
• /
• 2017

One of the important considerations in structural designing the flat plate system is ensuring the resistance to punching shear caused by axial loads and the ductile ability to follow horizontal deformation under earthquake. In this study, the ECC (Engineered Cementitious Composite) has been placed in the critical section zone of punching shear at slab-column joint to improve ductility and the advanced details of shear reinforced area nearby critical section zone has been developed using stud and steel fiber. The shear performance tests were performed on the specimens with parameters of fiber type mixed with ECC, stud and steel fiber set into the shear reinforced area in which the failure pattern, joint strength, displacement and strain of the specimen were compared and analyzed. The test results showed that the strength and ductility of specimens with ECC applied to joint were better than those of RC flat plate system. Also, the shear reinforcement effect of stud and the ductility improvement of steel fiber concrete were confirmed in the shear reinforcement area.

• Journal of Korean Society of Forest Science
• /
• v.96 no.3
• /
• pp.259-268
• /
• 2007

This study was conducted to produce forest thematic maps and estimate forest statistics for Pyeongchang Gun using the kNN technique, which has been applied to produce thematic maps of variables of interest including unobserved plots by combining field plot data, remotely sensed data and other digital map data in forest inventories. The estimation errors for three horizontal reference areas (HRAs), whose radii are 20, 40 and 60 km respectively, were compared. Although the precision for the 40 km radius was lower compared to that for the 60 km radius, the 40 km radius was found to be an efficient HRA because their difference in precision was modest. At a value of k=5 nearest neighbors for the selected HRA, the overall accuracy was high. As a result, using the k=5 neighbors within the HRA of 40 km radius, thematic maps of number of trees, basal area, and growing stock per hectare were generated. As compared to the forest statistics based on field sample plots, the estimated means of each parameter from the produced maps were underestimated.

• The korean journal of orthodontics
• /
• v.30 no.6 s.83
• /
• pp.687-698
• /
• 2000

The purpose of this study was to evaluate the changes of skeletodental patterns during Class II treatment and its retention period. Forty two patients of Class II malocclusion, which was treated with nonextraction or first premolar-extraction were selected and their lateral cephalograms were examined in this study. Various skeletodental changes in lateral cephalograms of pre-treatment, post-treatment and retention were measured by superimposition in reference to the cranial base for jaws, the palatal plane for maxillary teeth, and mandibular plane for mandibular teeth. The data were analyzed by paired t-test. In this study, occlusal plane showed the significant anterior downward steepening after active treatment, and remained during retention period. In the nonextraction group, maxillary incisors were retracted and extruded during treatment. Maxillary molars were extended, and mandibular molar were uprighted, with no mesial movement. In the extraction group, both maxillary and mandibular incisors were retracted and extruded. Maxillary molars were extruded and moved mesially, and mandibular molars were extruded and moved mesially with no mesial tilting. During retention period in both groups, there were tendencies of labial tipping of maxillary incisor, and mesial tipping of maxillary and mandibular molar. But the changes were not significant and most of teeth showed no change in vortical and horizontal direction.