• Geomechanics and Engineering
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• v.36 no.2
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• pp.167-181
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• 2024

The soil-structure relative stiffness is a key factor affecting the seismic response of underground structures. It is of great significance to study the soil-structure relative stiffness for the soil-structure interaction and the seismic disaster reduction of subway stations. In this paper, the dynamic shear modulus ratio and damping ratio of an inhomogeneous soft soil site under different buried depths which were obtained by a one-dimensional equivalent linearization site response analysis were used as the input parameters in a 2D finite element model. A visco-elasto-plastic constitutive model based on the Mohr-Coulomb shear failure criterion combined with stiffness degradation was used to describe the plastic behavior of soil. The damage plasticity model was used to simulate the plastic behavior of concrete. The horizontal and vertical relative stiffness ratios of soil and structure were defined to study the influence of relative stiffness on the seismic response of subway stations in inhomogeneous soft soil. It is found that the compression damage to the middle columns of a subway station with a higher relative stiffness ratio is more serious while the tensile damage is slighter under the same earthquake motion. The relative stiffness has a significant influence on ground surface deformation, ground acceleration, and station structure deformation. However, the effect of the relative stiffness on the deformation of the bottom slab of the subway station is small. The research results can provide a reference for seismic fortification of subway stations in the soft soil area.

• Journal of architectural history
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• v.20 no.5
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• pp.7-29
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• 2011

This research was to suggest the types according to structural system of the pagoda in ancient East-Asia and analyze the pagoda to the west of Mireuksaji temple site by these types. It will be possible to understand consistently the relation of the various form of the pagoda. The results of this research were described separately as follows. 1. The Buddhist pagodas founded in the ancient East Asia can be categorized according to their structural system, which provide us with insight to understand the interrelationship of categories. The pagoda is mainly classified into three categories. The first consists of two structures, an internal and an external structure. The second exposes its internal structure to the outside, and the third has the external components changing into the internal ones. 2. Although the pagoda to the west of Mireuksaji Temple Site have an internal and an external structures, it actually solves the structural problem by adopting the masonry structure in the outside as well as in the inside. Especially in this structural consideration can be found in the stylobate and the foundation structure of the pillar. The plan of the pagoda to the west of Mireuksaji Temple Site was intended to reveal the plane of the post-lintel layered construction which has a member, a main pillar, and the inner space in the cube with stones.

• The Journal of the Korean dental association
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• v.52 no.10
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• pp.615-622
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• 2014

Oral cancer ablation surgery results in tissue defects with functional loss. Accompanying neck dissection results in facial nerve weakness and dysmorphic changes. To minimize the complications after oral cancer surgery, accurate dissection without damaging facial nerve and vital structures are mandatory. Marginal mandibular branch of facial nerve should be dissected or contained in the superficial layer of deep cervical fascia to minimized facial palsy after operation. Reconstruction after cancer ablations is routine procedures and free flap reconstruction is the most commonly used. Radial forearm free flap is the most versatile flap to reconstruct soft tissue defects and it is easy to design according to the defect size and shape. However, donor site scar and secondary skin graft from thigh result in unesthetic and cumbersome wounds. Double layered collagen graft in the donor site could reduce secondary donor site for skin graft. In conclusion, oral and maxillofacial surgeon should know the exact anatomy of the face and neck during neck dissection. Radial forearm free flap is most versatile flap for soft tissue reconstruction and double collagen graft can reduce postoperative scar and there is no need for secondary skin graft.

• Bulletin of the Korean Chemical Society
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• v.24 no.5
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• pp.573-578
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• 2003

The structural, magnetic, and transport properties of a mono-layered manganite $La_{0.7}Sr_{1.3}MnO_{4+{\delta}}$ were investigated using variable temperature neutron powder diffraction as well as magnetization and transport measurements. The compound adopts the tetragonal I4/mmm symmetry and exhibits no magnetic reflection in the temperature region of 10 K ≤ T ≤ 300 K. A weak ferromagnetic (FM) transition occurs about 130 K, which almost coincides with the onset of a metal-insulator (M-I) transition. Extra oxygen that occupies the interstitial site between the [(La,Sr)O] layers makes the spacing between the [MnO₂] layers shorten, which enhances the inter-layer coupling and eventually leads to the M-I transition. We also found negative magneto resistance (MR) below the M-I transition temperature, which can be understood on the basis of the percolative transport via FM metallic domains in the antiferromagnetic (AFM) insulating matrix.

• Geomechanics and Engineering
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• v.13 no.5
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• pp.775-791
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• 2017

Surface wave techniques are widely used as non-invasive method for geotechnical site characterization. Field surface wave data are collected and analyzed using different processing techniques to generate the dispersion curves, which are further used to extract the shear wave velocity profile by inverse problem solution. Characteristics of a dispersion curve depend on the subsurface layering information of a vertically heterogeneous medium. Sometimes soft layer can be found between two stiff layers in the vertically heterogeneous media, and it can affect the wave propagation dramatically. Now most of the surface wave techniques use the fundamental mode Rayleigh wave propagation during the inversion, but this may not be the actual scenario when a soft layer is present in a vertically layered medium. This paper presents a detailed and comprehensive study using finite element method to examine the effect of soft layers which sometimes get trapped between two high velocity layers. Determination of the presence of a soft layer is quite important for proper mechanical characterization of a soil deposit. Present analysis shows that the thickness and position of the trapped soft layer highly influence the dispersion of Rayleigh waves while the higher modes also contribute in the resulting wave propagation.

• Journal of Electrochemical Science and Technology
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• v.14 no.3
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• pp.272-282
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• 2023

Ni-rich layered oxides cathode has recently gained attention as an advanced cathode material due to their applicable energy density. However, as the Ni component in the layered site is increased, the high reactivity of Ni⁴⁺ results in parasitic reaction associated with decomposing electrolyte, which leads to a rapid decreasing the lifespan of the cell. The electrolyte additive triallyl borate (TAB) improves interfacial stability, leading to a stable cathode-electrolyte interphase (CEI) layer on the LNCM83 cathode. A multi-functionalized TAB additive can produce a uniformly distributed CEI layer via electrochemical oxidation, which implies an increase in long-term cycling performance. After 100 cycles at elevated temperature, the cell tested by 0.75 TAB retained 88.3% of its retention ratio, whereas the cell performed by TAB-free electrolyte retained 64.1% of its retention. Once the TAB additive formed CEI layers on the LNCM83 cathode, it inhibited the decomposition of carbonate-based solvents species in addition to the dissolution of transition metal components from the cathode. The addition of TAB to LNCM83 cathode material is believed to be a promising way to increase the electrochemical performance.

• Journal of the Korean GEO-environmental Society
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• v.10 no.3
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• pp.5-12
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• 2009

This study presents static and dynamic strength of coal ashes collected from disposal site of power plant. Main compositions of coal ashes were bottom ashes. In order to evaluate static and dynamic characteristics of coal ash, NGI direct-simple shear tests, cyclic simple shear tests and direct shear tests were conducted. The strengths of coal ashes from those tests were compared to those of sands. Bottom ashes among coal ashes used for this study were classified as sand from the grain size distribution and show higher strength properties than the sands. For utilization of coal ashes in civil engineering project, mixing coal ashes with sandy soil using batch plant is inconvenient and the cost is higher than the spreading sand layer and coal layer alternately. In order to simulate both mixing type and layered type construction, sands and coal ashes were mixed with volume ratio 50:50 and prepared sand and coal ash layers alternately with the same volume ratio. From the tests mixed coal ashes-specimen shows slightly higher static and cyclic strength than the layered specimen at the same density. The higher strength seems due to the angular grain of bottom ashes. The cyclic stress ratio at liquefaction decreases rapidly as the number of cycle increases at mixed specimen than that of layered specimen.

• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.991-995
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• 2006

The layered double hydroxide with the insertion of chloride ions (LDH-Cl), which was synthesized by the co-precipitation method, was applied to investigate the fundamental aspects of the absorptive agent for phosphate removal from wastewater. The adsorption capacity was best described by the Langmuir-FreundIich isotherm, and the estimated isotherm parameters indicate that the LDH-CI capacity for the phosphate removal is much higher than that observed using a natural adsorbent material such iron oxide tailing. The kinetic experiment also showed that the LDH-Cl adsorption reaction rapidly at the adsorptive rate of 0.55 mg-P/g-LDH/min, implying that this adsorbent can be of use in the full-scale applications. The pH had a minimal effect on the LDH adsorption capacity in the range of 5 to 11, although the capacity dropped at the low pHs because of the change in LDH surface properties. Furthermore, other anions such as $Cl^-$ and $NO_3{^-}$ commonly found in the wastewater streams insignificantly affected the phosphate removal efficiencies, while $HCO_3{^-}$ ions had a negative effect on the LDH adsorption capacity due to its high selectivity. The phosphate removal experiment using the actual secondary effluent from a wastewater treatment plant showed the similar decrease in adsorption capacity, indicating that the bicarbonate ions in the wastewater were competing with phosphate for the adsorptive site in the surface of the LDH-Cl. Overall, the synthetic adsorbent material, LDH-Cl, can be a feasible alternative over other conventional chemical agents, since the LDH-Cl exhibits the high phosphate removal capacity with the low sensitivity to other environmental conditions.

• Journal of Korean Society of Rural Planning
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• v.24 no.1
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• pp.113-127
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• 2018

This study comprehends that the landscape of Ipsan Village is the accumulated output of the landscape management and social behavior by the historic personages through the reference research and field surveys. And the study sorted out the over-layered landscape characteristics of Ipsan Village by analyzing the dispersed landscape elements as follows. First, right before the start of Japanese invasions to Korea(1592-98), Tamjin(耽津) An(安) Family moved into Ipsan and started establishing the a single clan village. At a site with mountain background and facing the water(背山臨水), the village used to be a typical farming one with an organically planned road-system and housing area following the traditional order. However, the landscape has changed drastically since the 20th century with the construction of banks, roads and readjustment of arable land etc. Second, the original landscape, which can be figured out through the 'Gosanjaesibyukgyeong(高山齋十六景)' in the 18th century, shows its harmony with natural landscape: mountain & valley, stream & field, traditional trees, etc, cultural landscape: village, well, spring, etc, and momentary landscape: seasons, time, weather phenomena, sound, behavior, etc. Third, based on the second, 16 natural landscape elements: mountain & stream, planting, etc. and 25 cultural landscape elements: housing spaces, self-cultivation & ceremony spaces, community spaces and modern education & enlightenment spaces were selected and interpreted as landscaping meanings. Fourth, the over-layered landscape which stems from the compositive functions and inter-connectivity of landscape elements which consists Ipsan Village is regarded as 'Natural geographical and Fungsu landscape', 'Rural production and livelihood landscape', 'Confucian ceremony and symbolic landscape' and 'Modern education and enlightenment landscape.'

• Korean Journal of Materials Research
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• v.28 no.5
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• pp.273-278
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• 2018

Lithium-ion batteries have been considered the most important devices to power mobile or small-sized devices due to their high energy density. $LixCoO_2$ has been studied as a cathode material for the Li-ion battery. However, the limitation of its capacity impedes the development of high capacity cathode materials with Ni, Mn, etc. in them. The substitution of Mn and Ni for Co leads to the formation of solid solution phase $LiNi_xMn_yCo_{1-x-y}O_2$ (NMC, both x and y < 1), which shows better battery performance than unsubstituted $LiCoO_2$. However, despite a high discharge capacity in the Ni-rich compound (Ni > 0.8 in the metal site), poor cycle retention capability still remains to be overcome. In this study, aiming to improve the stability of the physical and chemical bonding, we investigate the stabilization effect of Ca in the Ni-rich layered compound $Li(Ni_{0.83}Co_{0.12}Mn_{0.05})O_2$, and then Ca is added to the modified secondary particles to lower the degree of cationic mixing of the final particles. For the optimization of the final grains added with Ca, the Ca content (x = 0, 2.5, 5.0, 10.0 at.%) versus Li is analyzed.