• Land and Housing Review
• /
• v.13 no.1
• /
• pp.141-150
• /
• 2022

Responding to the increasing demand for research on seismic resistance of structures triggered by a large-scale earthquake in Korea, the Ministry of the Interior and Safety revised the typical application of the existing seismic design standards with the national seismic performance target enhanced. Therefore, in this paper, the dam body of the aged Test-Bed and the penstock with fluid were modeled by the three-dimensional finite element method by introducing several variables. The current seismic design standard law confirmed the safety of the dam structure and penstock against seismic waves. As a result of the 3D finite element analysis, the stress change due to the water impact of the penstock was minimal, and it was confirmed that the effect of the hydraulic pressure was more significant than the water impact in the earthquake situation. When the hydrostatic pressure is in the form of SPH, it was analyzed that the motion of the fluid and the location of stress caused by the earthquake can be effectively represented, and it will be easier to analyze the weak part. As a result of the analysis, which considers penstock's corrosion, the degree of stress dispersion gets smaller because the penstock is embedded in the body. The stress result is minimal, less than 1% of the yield stress of the steel. In addition, although there is a possibility of micro-tensile cracks occurring in the inlet of the dam, it has not been shown to have a significant effect on the stress increa.

• The Journal of Engineering Geology
• /
• v.31 no.4
• /
• pp.561-577
• /
• 2021

The ten standard roughness profiles suggested by Barton and Choubey (1977) were extended to make three-dimensional (3D) joint models whose profiles were identical at any cross section. Replicas of joint models were produced using plaster of Paris, and direct shear tests were performed to verify the joint roughness coefficients (JRC) of the standard roughness profiles. Joint shear strengths measured by direct shear tests were compared with those predicted by the shear failure criterion suggested by Barton (1973) based on JRC, joint compressive strength (JCS), and joint basic friction angle (𝜙_b). Shear strengths measured from joints of the first and fourth standard roughness profiles were close to predicted values; however, shear strengths measured from the other joint models were lower than predicted, the differences increasing as the roughness of joints increased. Back calculated values for JRC, JCS, and from the results of the direct shear tests show measured shear strengths were lower than predicted shear strengths because of the JRC values. New JRC were back calculated from the measured shear strength and named JRC_m. Values of JRC_m were lower than the JRC for the standard roughness profiles but show a strong linear relationship to JRC. Corrected JRC_m values for the standard roughness profiles are provided and revised relationships between JRC_m and JRC, and new shear strength criterion are suggested.

• Journal of the Korean GEO-environmental Society
• /
• v.24 no.1
• /
• pp.5-14
• /
• 2023

In this study, the load transfer characteristics of the base and skin of drilled shafts were analyzed and the load sharing ratio was calculated by performing a load transfer large-scale model test and three-dimensional numerical analysis considering the similarity of drilled shafts, which is the design target. From the linear behavior of drilled shafts shown in the large-scale model test and 3D numerical analysis results, the skin load transition curve for the design conditions of this study was proposed by Baquelin et al., and the base load transition curve was proposed by Baquelin et al. For the horizontal load transition curve, the formula proposed by Reese et al. was confirmed to be appropriate. The test value was slightly larger than the numerical analysis value for the axial load at the rock socketing, but the load sharing ratio at the rock socketing increased, on average, about 27.8% as the vertical load increased. The analysis value of the vertical settlement of the pile head under the vertical load was evaluated to be slightly smaller than the test value, and the maximum vertical settlement of the pile head in the model test and analysis maximum vertical load was 10.6 mm in the test value and 10.0 mm in the analysis value, and the maximum vertical settlement value at the base of the pile was found to be a test value of 2.0 mm and an analysis value of 1.9 mm. The horizontal displacement at the head of the column (ground surface) and the head of the pile during the horizontal load was found to agree relatively well with the test value and the analysis value. As a result of the model soil test, the horizontal load measured at the maximum horizontal displacement of 38.0 mm was evaluated to be 24,713 kN, and the horizontal load in the numerical analysis was evaluated to be 26,073 kN.

• Journal of the Korean Electrochemical Society
• /
• v.27 no.3
• /
• pp.88-96
• /
• 2024

Lithium metal has garnered attention as a promising anode active material thanks to its high specific capacity, energy density, and the lowest reduction potential. However, the formation of dendrites, dendritic crystals that arise during the charge and discharge process, has posed safety and lifetime stability challenges. To resolve this, our study has introduced a novel separator design. This separator features a composite coating of vapor-grown carbon fiber, a conductive material in nanofibers, and silver. We have meticulously studied the impact of this innovative separator on the electrochemical properties of the lithium metal anode, unveiling promising results. To confirm the synergistic effect of VGCF and Ag, a separator with no surface treatment and a separator with only VGCF coated on one side were prepared and compared with the Ag-VGCF-separator. In the case of the bare separator, the Li metal surface is covered with dendrites during the initial charge and discharge process. In contrast, both the VGCF-separator and the Ag-VGCF-separator show Li precipitation inside the conductive coating layer coated on the separator surface. Additionally, the Ag-VGCF-separator showed a more uniform precipitate shape than the VGCF-separator. As a result, the Ag-VGCF-separators show improved electrochemical properties compared to the bare separators and the VGCF-separators.

• Journal of Korean Society of Forest Science
• /
• v.77 no.1
• /
• pp.32-42
• /
• 1988

This research was to establish the fundamental materials for the preservation and multiple-purpose management of forest vegetation of Dong Hwa Sa area located in the south facing slope of Mt. Pal-Gong. Analysis of forest vegetation of this area was studied by the method of Gentaro Toyohara, based on ZM School method and Pfister. The results obtained were summarized as follows. (1). Forest vegetation in this area divided into mountain forest and valley forest. (2). Mountain forest divided into A. Pinus densiflora community, B. Carpirtus laxiflora community, C. Quercus mongolica community. (3). Valley forest was formed mostly of Zelkova serrata community. (4). Piraus densiflora community divided into 1. Pines densiflora typical group, 2. Pines densiflora-Alnus hirsuta group, 3. Pines densiflora-Ilex macropoda group. (5). Quercus mongolica community divided into 1. Pinus densiflora-Carpinus cordata group, 2. Prunus sargentii-Hydrangea serrata for. acuminata group, (6). Zelkova serrata community divided into 1. Acer mono group, 2. Vine plant group. A vegetation analysis based on concepts and methods developed by Robert, D. Pfister and Gentaro Toyohara was considered to be effective on providing a guiding principle for a multiple-purpose management of forestry and a three-dimensional utilization of forest, but it is not easy for us to utilize such a analysis method because we are not rich in the materials of analysis of vegetation to our forest. Thus, It is necessary that we should collect much materials to various parts of forest in order that may utilize this method of analysis of vegetation.

• Korean Journal of Heritage: History & Science
• /
• v.46 no.2
• /
• pp.4-25
• /
• 2013

Goli-su is the innovative special kind of the embroidery technique, which combines twining and interlacing skill with metal technology and makes the loops woven to each other with a strand. The loops floating on the space of the ground look like floating veins of sculpture and give people the feeling of the openwork. This kind of characteristic has some similarities with the lacework craft of Western Europe in texture and technique style, but it has its own features different from that of Western Europe. It mainly represents the splendid gloss with metallic materials in the Embroidered cloth, such as gold foil or wire. In the 10th century, early days of Goryo, we can see the basic Goli-su structure form of its initial period in the boy motif embroidery purse unearthed from the first level of Octagonal Nine-storied Pagoda of Woljeong-sa. In the Middle period of Joseon, there are several pieces of Goli-su embroidered relic called "Battle Flag of Goryo", which was taken by the Japanese in 1592 and is now in the Japanese temple. This piece is now converted into altar-table covers. In 18~19th century, two pairs of embroidered pillows in Joseon palace were kept intact, whose time and source are very accurate. The frame of the pillows was embroidered with Goli-su veins, and some gold foil papers were inserted into the inside. The triangle motif with silk was embroidered on the pillow. The stitch in the Needle-Looped embroidery is divided into three kinds according to comprehensive classification: 1. Goli-su ; 2. Goli-Kamgi-su ; 3. Goli-Saegim-su. From the 10th century newly establishing stage to the 13th century, Goli-su has appeared variational stitches and employed 2~3 dimensional color schemes gradually. According to the research of this thesis, we can still see this stitch in the embroidery pillow, which proves that Goli-suwas still kept in Korea in the 19th century. And in terms of the research achievement of this thesis, Archetype technology of Goli-su was restored. Han Sang-soo, Important Intangible Cultural Heritage No. 80 and Master of Embroidery already recreated the Korean relics of Goli-su in Joseon Dynasty. The Needle-Looped embriodery is the overall technological result of ancestral outstanding Metal craft, Twining and Interlacing craft, and Embroidery art. We should inherit, create, and seek the new direction in modern multi-dimensional and international industry societyon the basis of these research results. We can inherit the long history of embroidering, weaving, fiber processing, and expand the applications of other craft industries, and develop new advanced additional values of new dress material, fashion technology, ornament craft and artistic design. Thus, other crafts assist each other and broaden the expressive field to pursue more diversified formative beauty and beautify our life abundantly together.

• Structural Engineering and Mechanics
• /
• v.41 no.2
• /
• pp.183-204
• /
• 2012

Several issues regarding the structural idealization of steel buildings with perimeter moment resisting steel frames (MRSFs) and interior gravity frames (GFs) are studied. Results indicate that the contribution of GFs to the lateral structural resistance may be significant. The contribution increases when the stiffness of the connection of the GFs is considered and is larger for inelastic than for elastic behavior. The interstory shears generally increase when the connections stiffness is taken into account. Resultant stresses at some base columns of MRSFs also increase in some cases but to a lesser degree. For columns of the GFs, however, the increment is significant. Results also indicate that modeling the building as planes frames may result in larger interstory shears and displacements and resultant stresses than those obtained from the more realistic 3-D formulation. These differences may be much larger when semi-rigid (SR) connections are considered. The conservativism is more for resultant stresses. The differences observed in the behaviour of each structural representation are mainly due to a) the elements that contribute to strength and stiffness and b) the dynamics characteristics of each structural representation. It is concluded that, if the structural system under consideration is used, the three-dimensional model should be used in seismic analysis, the GFs should be considered as part of the lateral resistance system, and the stiffness of the connections should be included in the design of the GFs. Otherwise, the capacity of gravity frames may be overestimated while that of MRSFs may be underestimated.

• Journal of Biomedical Engineering Research
• /
• v.37 no.1
• /
• pp.39-45
• /
• 2016

A pressure measurement system was developed to verify magnitude and position of transferred pressure on the body surface during the intermittent pneumatic compression (IPC) which is one of the most well-known methods for the prevention of deep vein thrombosis (DVT). Eighty force sensing resistors (FSR) were arranged on a mannequin leg and a hardware controller sensed, digitized, and transferred pressure data every second while IPC was being applied. Finally, sensed pressure data were color coded and visualized on the 3D model with lab-developed software. The pressure data were also saved to files for further analysis. Using this measurement system, the changing pattern of pressure was measured on the mannequin leg by changing both chamber pressure and cuff tightness. As a result, net pressure transferred onto the body surface is dependent on chamber pressure and cuff tightness. Under the same chamber pressure, the tighter a cuff was worn, the wider compressed area was and the shorter compression cycle was. Also transferred pressure was proportional to both chamber pressure and cuff tightness.

• Steel and Composite Structures
• /
• v.18 no.1
• /
• pp.1-28
• /
• 2015

In this paper, the dynamic response of functionally gradient steel (FGS) composite cylindrical panels in steady-state thermal environments subjected to impulsive loads is investigated for the first time. FGSs composed of graded ferritic and austenitic regions together with bainite and martensite intermediate layers are analyzed. Thermo-mechanical material properties of FGS composites are predicted according to the microhardness profile of FGS composites and approximated with appropriate functions. Based on the three-dimensional theory of thermo-elasticity, the governing equations of motionare derived in spatial and time domains. These equations are solved using the hybrid Fourier series expansion-Galerkin finite element method-Newmark approach for simply supported boundary conditions. The present solution is then applied to the thermo-elastic dynamic analysis of cylindrical panels with three different arrangements of material compositions of FGSs including ${\alpha}{\beta}{\gamma}M{\gamma}$, ${\alpha}{\beta}{\gamma}{\beta}{\alpha}$ and ${\gamma}{\beta}{\alpha}{\beta}{\gamma}$ composites. Benchmark results on the displacement and stress time-histories of FGS cylindrical panels in thermal environments under various pulse loads are presented and discussed in detail. Due to the absence of similar results in the specialized literature, this paper is likely to fill a gap in the state of the art of this problem, and provide pertinent results that are instrumental in the design of FGS structures under time-dependent mechanical loadings.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.37 no.6
• /
• pp.799-808
• /
• 2013

Previous research reported that body size measured as Body Mass Index (BMI) and body shape measured as waist-hip-ratio (WHR) are two essential factors that form the perceptions of body attractiveness. However, the debate on the importance of BMI versus WHR is ongoing. In addition, scholarly articles, that focus on the role of geographic and cultural variability on perceptions of attractiveness, report inconsistent results. Some suggested that according to globalization and the rise of mass media, geographic variability of perceptions of attractiveness have been altered, while others believed that it remains. This study cross-regionally investigates the role of body size and body shape on the perceptions of female attractiveness. Samples were composed of 107 female college students in Alabama and 107 female college students in California. Participants viewed 27 three-dimensional body scan images of women in three body shapes (pear, hourglass, and rectangle) and three body sizes (underweight, normal weight, and overweight) and rated their perceptions of attractiveness. Images were shown to students in a random order with an overhead projector and Microsoft Office PowerPoint software. A three-way mixed-ANOVA was conducted to analyze the data. The results of the study showed that some regional differences exist between the two sample groups. However, regardless of the regional difference, hourglass shapes were perceived to be the most attractive shape and underweight sizes were perceived to be the most attractive size for both samples.