• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.300-309
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• 2016

Curved beams are increasingly used in buildings, vehicles, ships, and aircraft, which has resulted in considerable effort towards developing an accurate method for analyzing the dynamic behavior of such structures. The stability behavior of elastic curved beams has been the subject of many investigations. Solutions to the relevant differential equations have traditionally been obtained by the standard finite difference or finite element methods. However, these techniques require a great deal of computer time for a large number of discrete nodes with conditions of complex geometry and loading. One efficient procedure for the solution of partial differential equations is the differential quadrature method (DQM). This method has been applied to many cases to overcome the difficulties of complex algorithms and high storage requirements for complex geometry and loading conditions. Out-of-plane buckling of curved beams with rotatory inertia were analyzed using DQM under uniformly distributed radial loads. Critical loads were calculated for the member with various parameter ratios, boundary conditions, and opening angles. The results were compared with exact results from other methods for available cases. The DQM used only a limited number of grid points and shows very good agreement with the exact results (less than 0.3% error). New results according to diverse variation are also suggested, which show important roles in the buckling behavior of curved beams and can be used for comparisons with other numerical solutions or experimental test data.

• Korean Journal of Ichthyology
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• v.33 no.2
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• pp.107-116
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• 2021

Two stone loaches (Nemacheilidae, Cypriniformes), Barbatula toni (Dybowski, 1869) and B. nuda (Bleeker, 1864), have been recognized in the Korean waters to date. Recently, due to indiscriminate artificial introduction as well as the change of their habitats induced by natural disasters, it seems to be concerned about the damage of species-specific geographic boundaries. We examined the genetic difference of two Korean Barbatula species by the haplotype network based on the Cytochrome b sequences of mitochondrial DNA and the phylogenetic relationships among them including Barbatula fishes occurring around the Korean peninsula. As a result, three and 29 haplotypes were obtained from B. toni and B. nuda, respectively, and totally three clades comprising "toni group", "nuda hangang group", and "nuda donghae group" were identified. The sequence variable sites among them was 10~24%, showing a difference of interspecific level. Phylogenetic relationships of the latter group, especially, forms an independent cluster discriminating with other two groups as well as the Chinese, Japanese, Russian, and European Barbatula species, suggesting the possibility of the specific level divergence.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.9-17
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• 2021

Curved beams are increasingly used in buildings, vehicles, ships, and aircraft, which has resulted in considerable effort being directed toward developing an accurate method for analyzing the dynamic behavior of such structures. The stability behavior of elastic circular arches has been the subject of a large number of investigations. One of the efficient procedures for the solution of ordinary differential equations or partial differential equations is the differential quadrature method DQM. This method has been applied to a large number of cases to overcome the difficulties of the complex computer algorithms, as well as excessive use of storage due to conditions of non-linear geometries, loadings, or material properties. This study uses DQM to analyze the in-plane vibration of the circular arches considering the effects of midsurface extension and rotatory inertia. Fundamental frequency parameters are calculated for the member with various parameter ratios, boundary conditions, and opening angles. The solutions from DQM are compared with exact solutions or other numerical solutions for cases in which they are available and given to analyze the effects of midsurface extension and rotatory inertia on the frequency parameters of the circular arches.

• Korean Journal of Construction Engineering and Management
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• v.23 no.1
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• pp.46-53
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• 2022

The railway platform is an important facility closely related to the safety of passengers, trains, and images of railway facilities, and requires thorough facility management. However, the problem that the finishing material (plastering mortar) for the joint finishing of dissimilar materials (concrete+granite) falls off in the direction of the track at the platform podium is occurring multiple times across the country. Since these problems threaten the safety of train operation and the safety of passengers, immediate and continuous management is required. This study tried to derive improvement plans through the analysis of the drop-off problem of finishing materials occurring at the platform podium. The status of missing finishing materials for the platform podiums of about 200 railway stations and the related design and construction standards of the Korea National Railway were investigated. After that, the cause of the drop-off of the finishing material was analyzed, and as a result, it was found that the main cause was the boundary between the roadbed and the architectural process that occurred during construction. Subsequently, in connection with the derived causes and design, construction standards, (1) improvement of finishing materials or construction methods, (2) design of finishing materials that are easy to adjust height, (3) design of separate finishing methods, (4) improvement methods and durability were suggested.

• Journal of the Korean Geotechnical Society
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• v.39 no.2
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• pp.19-30
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• 2023

Underground structures, such as compacted sand piles applied as soft ground countermeasures, are analyzed for settlement and stability by the composite ground design method. The basic principle of the composite ground design method is the arching effect. The reinforcing effect of the pile is evaluated as the stress-distribution ratio. When applying grouting piles with elastic properties using the ground reinforcement method, the existing stress-distribution ratio was only considered when the pile was installed. This study shows that the method of applying the stress-distribution ratio applied in previous studies should be changed when the ground reinforcement pile is installed at an arbitrary location in the ground without raising it to the ground surface. When high strength jet routing is applied, the stress-distribution ratio (n) to the in-situ ground generally ranges from 30 to 50. However, if the pile is located far from the surface and the depth goes down to the boundary depth of the stress sphere, the stress-distribution effect rapidly decreases, and the stress-distribution ratio converges to 1.5.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1272-1278
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• 2011

This study was conducted to reclassify Cheongweon series based on the second edition of Soil Taxonomy and to discuss the formation of Cheongweon series distributed on broad continental alluvial plains. Morphological properties of typifying pedon of Cheongweon series were investigated and physico-chemical properties were analyzed according to Soil survey laboratory methods manual. The typifying pedon of Cheongweon series has dark grayish brown (2.5Y 4/2) silt loam Ap horizon (0~18 cm), dark grayish brown (2.5Y 4/2) silt loam BA horizon (18~30 cm), dark yellowish brown (10YR 4/6) silty clay loam Bt1 horizon (30~60 cm), strong brown (7.5YR 4/6) silty clay loam Bt2 horizon (60~91 cm), brown (10YR 4/4) silt loam BC horizon (91~104 cm), and mottled (7.5YR 4/6, and 7.5YR 5/2) silt loam C horizon (104~160 cm). The typifying pedon has an argillic horizon from a depth of 30 to 91 cm and a base saturation (sum of cations) of 35% or more at 125 cm below the upper boundary of the argillic horizon. It can be classified as Alfisol, not as Incceptisol. It has udic soil moisture regime, and can be classified as Udalf. Also that meets the requirements of Hapluadalf. It has anthraquic condition, and keys out as Anthraquic Hapludalf. That has fine silty textural family, and has mesic soil temperature regime. Therefore Cheongweon series can be classified as fine silty, mixed, mesic family of Anthraquic Hapludalfs, not as fine silty, mixed, mesic family of Fluvaquentic Epiaquepts.

• Economic and Environmental Geology
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• v.50 no.4
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• pp.303-311
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• 2017

The laboratory scale experiment was performed to evaluate the sealing capacity of the capping rock such as tuff and mudstone, measuring the intial supercritical $CO_2$ ($scCO_2$) injection pressure and the $scCO_2$-water-rock reaction for 90 days. The drilling cores sampled from 800 m in depth around the Janggi basin, Korea were used for the experiment. The mineralogical changes of mudstone and tuff were measured to evaluate the geochemical stability during the $scCO_2$-water-rock reaction at $CO_2$ storage condition (100 bar and $50^{\circ}C$). The rock core was fixed in the high pressurized stainless steel cell and was saturated with distilled water at 100 bar of pore water pressure. The effluent of the cell was connected to the large tank filled with 3 L of water and 2 L of $scCO_2$ at 100 bar, simulating the subsurface injection condition. The $scCO_2$ injection pressure, which was higher than 100 bar, was controlled at the influent port of the cell until the $scCO_2$ begin to penetrate into the rock and the initial injection pressure (> 100 bar) of $scCO_2$ into the rock was measured for each rock. The mineralogical compositions of mudstones after 90 days reaction were similar to those before the reaction, suggesting that the mudstone in the Janggi basin has remained relatively stable for the $scCO_2$ involved geochemical reaction. The initial $scCO_2$ injection pressure (${\Delta}P$) of a tuff in the Janggi basin was 15 bar and the continuous $scCO_2$ injection into the tuff core occurred at higher than 20 bar of injection pressure. For the mudstone in the Janggi basin, the initial $scCO_2$ injection pressure was higher than 150 bar (10 times higher than that of the tuff). From the results, the mudstone in Janggi basin was more suitable than the tuff to shield the $scCO_2$ leakage from the reservoir rock at subsurface.

• Journal of the Korean Geotechnical Society
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• v.22 no.6
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• pp.71-82
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• 2006

One of the most popular pre-reinforcement methods of tunnel heading in cohesionless soils would be the fore-polling of grouted pipes, known as RPUM (reinforced protective umbrella method) or UAM (umbrella arch method). This technique allows safe excavation even in poor ground conditions by creating longitudinal arch parallel to the tunnel axis as the tunnel advances. Some previous studies on the reinforcing effects have been performed using numerical methods and/or laboratory-based small scale model tests. The complexity of boundary conditions imposes difficulties in representing the tunnelling procedure in laboratory tests and theoretical approaches. Full-scale study to identify reinforcing effects of the tunnel heading has rarely been carried out so far. In this study, a large scale model testing for a tunnel in granular soils was performed. Reinforcing patterns considered are four cases, Non-Reinforced, Crown-Reinforced, Crown & Face-Reinforced, and Face-Reinforced. The behavior of ground and pipes as reinforcing member were fully measured as the surcharge pressure applied. The influences of reinforcing pattern, pipe length, and face reinforcement were investigated in terms of stress and displacement. It is revealed that only the Face-Reinforced has decreased sufficiently both vertical settlement in tunnel heading and horizontal displacement on the face. Vertical stresses along the tunnel axis were concentrated in tunnel heading from the test results, so the heading should be reinforced before tunnel advancing. Most of maximum axial forces and bending moments for Crown-reinforced were measured at 0.75D from the face. Also it should be recommended that the minimum length of the pipe is more than l.0D for crown reinforcement.

• Korean Journal of Environmental Biology
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• v.35 no.3
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• pp.380-388
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• 2017

Factors affecting spatial distribution of halophytes were analyzed in June 2012 at the Goraebul coastal dunes. In the Goraebul sand dune, distribution of halophytes was divided into three groups. The first group belonging to Elymus mollis, Carex kobomugi, Calystegia soldanella, Ixeris repens and Glehnia littoralis was distributed in the ridge of primary sand dune and dune slack. The second group belonging to Lathyrus japonicus and Zoysia macrostachya was distributed in the dune slack. The third group belonging to Pinus thunbergii, Vitex rotundifolia and Linaria japonicus was distributed in the pine forest of the secondary sand dune. E. mollis, C. kobomugi, C. soldanella, I. repens and G. littoralis was distributed in relatively unstable habitat of sand dunes due to the large amount of sand movement. V. rotundifolia was distributed in a relatively stable habitat. Factors that have the greatest influence on distribution of halophytes in the Goraebul sand dunes are distance from the seashore, topography, and the pine forest. The Goraebul sand dune is a relatively well-preserved area with minimal human intervention. Therefore, different distribution of physico-chemical factors by natural processes is essential to spatial distribution of halophytes than other sand dunes in Korea. Significant natural processes in the Goraebul sand dunes were advance and retreat of coastlines from waves, erosion and sedimentation of sand due to wind and waves, and dispersal of seawater.

• Science of Emotion and Sensibility
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• v.10 no.2
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• pp.273-280
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• 2007

The study is to examine the psychophysiological responses evoked by negative emotions(fear and disgust) in children. 47 children(11-13 years old, 23 boys) participated in the study. While the children were experiencing fear or disgust emotion induced by audio-visual film clips, ECG, EDA, PPG and SKT are measured. Emotion assessment scale was used to confirm that emotions elicited by the film clips were significantly noticeable, which was measured self-report. The results turned out to be 100% and 89.4% of appropriate for fear and disgust emotions, respectively. Emotional intensity the children had experienced was rated as 4.05, 4.07 on 1-5 scale based on effectiveness of measurement of fear and disgust emotion. ANS reponses by fear and disgust were significantly between the resting state and emotional state induced. The result obtained from the fear emotion showed significant increases in SCL, NSCR, HR, RSA, RESP and HF. There was a significant difference in SCL and NSCR between the two emotions.