• Journal of the Korean GEO-environmental Society
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• v.15 no.6
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• pp.41-48
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• 2014

In this study, the behavior of fill dam with continuous water level change considering velocity changes via centrifugal model test was investigated. In addition, the collapse of fill dam due to the overflow was also experimentally simulated. The experimental results demonstrate that the pore water pressures and displacements vary in proportion to the water-level-change velocity, and the displacement increment is independent to the water-level-change velocity. Also, it is confirmed that the continuous water level change induces to the progress of fill-dam deformation due to displacement accumulation and the fill-dam stability dramatically degrades owing to the overflow. Hence, the real-time monitoring of pore water pressures and displacements of fill dam, and the control of water level in heavy rain through the countermeasure such as opening sluice gates are needed to ensure the stability of fill dam.

• BMB Reports
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• v.55 no.4
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• pp.181-186
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• 2022

Ventriculomegaly induced by the abnormal accumulation of cerebrospinal fluid (CSF) leads to hydrocephalus, which is accompanied by neuroinflammation and mitochondrial oxidative stress. The mitochondrial stress activates mitochondrial unfolded protein response (UPRmt), which is essential for mitochondrial protein homeostasis. However, the association of inflammatory response and UPRmt in the pathogenesis of hydrocephalus is still unclear. To assess their relevance in the pathogenesis of hydrocephalus, we established a kaolin-induced hydrocephalus model in 8-week-old male C57BL/6J mice and evaluated it over time. We found that kaolin-injected mice showed prominent ventricular dilation, motor behavior defects at the 3-day, followed by the activation of microglia and UPRmt in the motor cortex at the 5-day. In addition, PARP-1/NF-κB signaling and apoptotic cell death appeared at the 5-day. Taken together, our findings demonstrate that activation of microglia and UPRmt occurs after hydrocephalic ventricular expansion and behavioral abnormalities which could be lead to apoptotic neuronal cell death, providing a new perspective on the pathogenic mechanism of hydrocephalus.

• Journal of the Korean Geotechnical Society
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• v.39 no.11
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• pp.33-40
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• 2023

This study explores the performance of pile foundations in highly expansive soil, incorporating magnesium oxide-based refractory materials. A controlled model chamber, housing a fixed pile, was utilized to induce ground expansion through fused magnesia (FM). The investigation focused on measuring the vertical displacement of FM-sand mixtures and the axial load on the pile in relation to depth and time. The study varied the amount of FM content (FM_c) at 30%, 50%, and 70%. The upward movement exhibited an augmentation with increasing FM_c, tapering off with depth as accumulation progressed toward the mixture surface. Compression and tensile forces were both evident along the pile for FM_c at 30% and 50%, while only a tensile force was observed at an FM_c of 70%. These results offer valuable insights for the analysis of pile behavior within FM-sand mixtures.

• Nuclear Engineering and Technology
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• v.56 no.9
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• pp.3785-3795
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• 2024

The present study concerned with the activity concentrations of natural radionuclides (²³⁸U, ²³⁴U, ²³⁰Th, ²²⁶Ra, ²³²Th, ⁴⁰K and, ²³⁵U) in ten sedimentary rock samples collected from fault zone, Gabal Um Hamd, southwestern Sinai, Egypt. These samples were investigated to study their behavior during a part of geologic time. The activity concentrations were measured using γ-ray spectrometry (HPGe detector). The investigated samples were analyzed for major oxides using the XRF technique. The results demonstrated high average activity concentrations of ²³⁸U, ²³⁴U, ²³⁰Th, ²²⁶Ra, ²³²Th, ⁴⁰K and, ²³⁵U than the worldwide average values as reported by UNSCEAR 2008. Theil diagram showed that there are accumulation and leaching of uranium in some samples in the two sides of the fault zone. It is noticed that the ages of uranium depositions for the samples collected from the downthrown of the fault zone vary from 121.5 to 440.1 ky, while for the sample collected from the upthrown of the fault is 210.9 ky. The ²³⁰Th/²³²Th activity ratios range between 4.55 and 91.04 for downthrown samples and between 4.75 and 6.05 for upthrown samples which are smaller than 20 except for two samples, indicating a contamination of the samples by detrital ²³⁰Th. After subtraction of the detrital ²³⁰Th, the corrected ages for downthrown samples vary from 119.1 to 231.7 ky while for upthrown samples vary from 164.4 to 390 ky.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.6
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• pp.881-888
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• 1993

A new stabilizing algorithm for the fast transversal filter (FTF) which is known to exhibit a very unstable behavior, due basically to the accumulation in two different ways, we define a emasure counting these at each step of the algorithm in order to reduce the roundoff error. It has been shown that required amount of computation for the proposed algorithm is linearly increased as the order of equalizer and that stability is improved in comparison with the other existing algorithm. It has been shown that the proposed algorithm exhibits a good performance using computer simulation of adaptive equalization for multipath fading channel in urban mobile radio environment.

• Journal of Environmental Science International
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• v.23 no.3
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• pp.473-481
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• 2014

Poly(lactide)s(PLA) is an attractive material to solve the problem of waste plastic accumulation in nature because of its biodegradability. The lactide exists in three stereoisomeric configurations: L-lactide, D-lactide, and meso-lactide. PLA stereocomplexes, formed by the mixing of two enantiomers, poly(L-lactide)(PLLA) and poly(D-lactide)(PDLA), have many favorable characteristics because the stereocomplex showed $50^{\circ}C$ higher melting point than each enantiomeric polymer and the resistance toward degradation increased. In this study, we investigated the influence of the composition and the optical purity of each component on the formation of stereocomplexes. Also, the nanofibers of stereochemical PLA and their blends were prepared by electrospinning method. The properties of the obtained fibers were analyzed by differential scanning calorimetry and scanning electron microscopy. The results showed that a degree of stereocomplex was controlled by change of optical purity of each component. The enzymatic degradation of the fibers were strongly dependent on the stereocomplex.

• Bulletin of the Korean Chemical Society
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• v.24 no.4
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• pp.437-440
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• 2003

In a mediator-aided microbial fuel cell, the choice of a proper mediator is one of the most important factors for the development of a better fuel cell system as it transfers electrons from bacteria to the electrode. The electrochemical behaviors within the lipid layer of two representative mediators, thionin and safranine O both of which exhibit reversible electron transfer reactions, were compared with the fuel cell efficiency. Thionin was found to be much more effective than safranine O though it has lower negative formal potential. Cyclic voltammetric and fluorescence spectroscopic analyses indicated that both mediators easily penetrated the lipid layer to pick up the electrons produced inside bacteria. While thionin could pass through the lipid layer, the gradual accumulation of safranine O was observed within the layer. This restricted dynamic behavior of safranine O led to the poor fuel cell operation despite its good negative formal potential.

• Development and Reproduction
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• v.2 no.2
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• pp.115-133
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• 1998

Recently public concerns about the endocrine disrupting chemicals (EDC) have resulted in the increased legistrative and regulatory attentions in many countries. Endocrine disrupter is an exogeneous chemical interfering the synthesis, transport binding, action or elimination of natural hormones in the body, which are responsible for the maintenance of homeostasis, reproduction, development and/or behavior. Reported possible harmful effects on human and animal lives, possible developmental anomalities, reproductive malfunctions and behaviors, and the ways of EDC accumulation in animal kingdom are reviewed. The current scientific papers and knowledges on the global contamination of EDCs demonstrates the conclusive data that EDCs have the potentials to cause the calamitous extermination of human and animal species by the global contamination.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.3
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• pp.348-357
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• 2000

The purpose of this study is to examine the effect of partial osseointegration situation on bone loading patterns around two different free-standing screw shaped implants (Nobel Biocare, Gothenburg, Sweden and Degussa-Huls, Hanau, German). Two dimensional axisymmetric Finite element models of two implants(10mm length and 4mm diameter) were created according to different bone quantity, quality and osseointegration ratio in maxilla and mandible bone. At the same time uni-cortical and hi-cortical fixation were analyzed. Generally, full bond case showed less stress than partial bond case in overall area and mandibular model showed less amount of stress than that of maxilla model. Maximum stress of the Branemark implant is higher than that of ANKYLOS regardless of bonding ratio at crestal and apex region. However, more stress concentration was noted in ANKYLOS implant at screw body area especially in mandible. The effect of bicortical fixation on crestal bone stress reduction is dramatical in mandible however, there was no significant effect in maxillary case. The effect of partial bond on stress distribution was more significant at screw body and apex region than in crestal region. Partial bond cases demonstrated greater stress accumulation in trabecular bone than cortical bone. It is concluded that the more accurate model of implant and bone which affects stress and strain distribution is needed to mimic in vivo behavior of implants.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04c
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• pp.69-72
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• 2008

Decay processes of accumulated charge in e-beam irradiated polymers during elevating temperature are observed using pulsed electro-acoustic measurement system. Since the polymeric materials have many superior properties such as light-weight, good mechanical strength, high flexibility and low cost, they are inevitable materials for spacecrafts. In space environment, however, the polymers sometimes have serious damage by irradiation of high energy charged particles. When the polymers of the spacecraft are irradiated by high energy charged particles, some of injected charges accumulate and remain for long time in the bulk of the polymers. Since the bulk charges sometimes cause the degradation or breakdown of the materials, the investigation of the charging and the decay processes in polymeric materials under change of temperature is important to decide an adequate material for the spacecrafts. By measuring the charge behavior in e-beam irradiated polymer, such as polyimide or polystyrene, it is found that the various accumulation and decay patterns are observed in each material. The results seem to be useful and be helpful to progress in the reliability of the polymers for the spacecraft.