• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.722-729
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• 2004

Leptin is an adipocyte-secreted hormone and its plasma levels correlate with total body fat mass, however, it also plays a regulatory role in immunity, inflammation, and hematopoiesis. Chemokine is known as a chemoattractant cytokine in inflammatory reaction, but its role in leptin reaction has not been well studied. In this study, the direct effect of leptin on the expression of chemokine mRNAs and lipopolysaccharide (LPS)-induced chemokine KC mRNA in mouse peritoneal macrophages was investigated. Leptin did not induce the expression of lymphotactin, RANTES, eotaxin, MIP-1$\beta$, MIP-1$\alpha$, MIP-2, MCP-1, IP-10, TCA-3, and KC mRNA in mouse peritoneal macrophages, and had no direct effect on the expression of these LPS-induced chemokine mRNAs except KC mRNA. The synergistic effect of leptin on the expression of LPS-induced KC mRNA occurred late in the time course of response to LPS. The increased expressions of Ob-Rb mRNA and leptin receptor protein were detected during the LPS treatment. Leptin produced a substantial increase in the stability of the LPS-induced KC mRNA, and the synergistic effect of leptin on LPS-induced KC mRNA expression was further augmented by cycloheximide (CHX). Pyrrolidine dithiocarbamate (PDTC) did not block the synergistic effect of leptin on LPS-induced KC mRNA expression in mouse peritoneal macrophages. These data suggest that although leptin has no direct effect on the expression of lymphotactin, RANTES, eotaxin, MIP-1$\beta$, MIP-1$\alpha$, MIP-2, MCP-1, IP-10, TCA-3, and KC mRNA in mouse peritoneal macrophages, the synergistic effect of leptin on the expression of LPS-induced KC mRNA has the possibility that LPS might induce the expression of the Ob-Rb receptor or an unknown gene(s) that sensitizes macrophages to the synergistic function of leptin. Therefore, further studies are necessary to examine leptin as a regulatory factor of chemokine production.

• Radiation Oncology Journal
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• v.17 no.3
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• pp.256-260
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• 1999

Purpose : An investigation has been carried out on the factors which affect the response reading of thermoluminescent dosimeters (TLD-100) loaded with thin material in high energy Photon. The aim of the study was to assess the energy response of TLD-100 to the therapeutic ranges of photon beam. Materials and Methods : In this technique, TLD-100 (abbreviated as TLD) chips and three different thin material (Tin, Gold, and Tissue equivalent plastic plate) which mounted on the TLD chip were used in the clinical photon beam. The thickness of each metal plates was 0.1 mm and TE plastic plate was 1 mm thick. These compared with the photon energy dependence of the sensitivities of TLD (normal chip), TLD loaded with Tin or Gold plate, for the photon energy range 6 MV to 15 MV, which was of interest in radiotherapy. Results : The enhancement of surface dose in the TLD with metal plate was clearly detected. The TLD chips with a Gold plate was found to larger response by a factor of 1.83 in 10 MV photon beam with respect to normal chip. The sensitivity of TLD loaded with Tin was less than that for normal TLD and TLD loaded with Gold. The relative sensitivity of TLD loaded with metal has little energy dependence. Conclusion : The good stability and linearity with respect to monitor units of TLD loaded with metal were demonstrated by relative measurements in high energy Photon ($6\~15$ MV) beams. The TLD laminated with metals embedded system in solid water phantom is a suitable detector for relative dose measurements in a small beam size and surface dose.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.18 no.1
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• pp.135-143
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• 1996

The aim of this study was to evaluate bone promotion of bioreabsorbable guided tissue regeneration for generating new bone adjacent to osseointegrated implants in dogs. Third premolars were extracted in dgo mandibles. Cylindrical HA-coated implants were placed into extracted sockets in dogs. And test sites were protected by $GUIDOR^{(R)}$ matrix barrier. But control sites were not protected by membrances. The sites were examined clinically, radiologically, and histologically after 1, 2, and 4 months to assess bone regeneration. The results obtained were as foolows : 1. There were the good healing and the stability of $GUIDOR^{(R)}$ matrix barrier in experimental site during the healing period. 2. Complete resorption of $GUIDOR^{(R)}$ matrix barrier was clinically observed about 4 months postoperatively. 3. The woven bone changed to mature bone with a normal cortical plate and mature, resting periosteum after 4 months. 4. In experimental site, there was a significantly greater bone promtion than observed in control site. 5. $GUIDOR^{(R)}$ matrix barrier was useful for the preparation of immediate dental implants.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.101-115
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• 2016

We carried out laboratory material tests on two cements (KS-1 ordinary Portland and Class G) with changing W/S (Water/Solid) and the content of fly ash in order to evaluate their physical and mechanical properties. The specimens of KS-1 ordinary Portland cement were prepared with varying W/S (Solid=cement) in weight, while those of Class G cement were prepared with changing the content of fly ash in volume but maintaining W/S (Solid=cement+fly ash). The results of the material tests show that as the W/S in KS-1 ordinary Portland cement and the content of fly ash in Class G cement increase, the properties (density, sonic wave velocity, elastic constants, compressive and tensile strengths, thermal conductivity) decrease, but porosity and specific heat increase. In addition, an increase in confining pressure and in the content of fly ash leads to plastic failure behavior of the cements. The laboratory data were then used in a stability analysis of cement sheath for which an analytical solution for computing the stress distribution induced around a cased, cemented well was employed. The analysis was carried out with varying the injection well parameters such as thickness of casing and cement, injection pressure, dip and dip direction of injection well, and depth of injection well. The analysis results show that cement sheath is stable in the cases of relatively lower injection pressures and inclined and horizontal wells. However, in the other cases, it is damaged by mainly tensile failure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.725-730
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• 2017

The strength ratio of the main structures of buildings gradually increasing, due to the advances made in analysis and cost saving techniques. In this study, to examine the stability of industry buildings using sandwich panels as roof assemblies, we examine the changes in the moment strength ratio of the main structures caused by increasing the roof load. This study adopts the PEB structure and three H-steel structure as the structural analysis models. In the case where the additional load exceeds about 11% of the roof design load, the strength ratio exceeds 1 for the main structure. In the case where the additional load exceeds about 36%(of the roof design load), the working moment exceeds the plastic moments, which leads to major damage to the structure. This study compares 1) the maximum load according to the purlin spaces, 2) the maximum load by KS, and 3) the maximum load calculated from the test results of the manufacturer.The maximum bearing load of the panels determined by all three methods exceeds the structure failure threshold load of the main structure. This study provides evidence that an unexpected increase in the roof load might cause the whole structure to collapse, due to the failure of the main structural members, before the failure of the roof assemblies. Therefore, information on the structural performance of the sandwich panels is required for the structural design, and the sandwich panels should be considered to be an integral part of the overall structural design.

• Tunnel and Underground Space
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• v.14 no.5
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• pp.327-338
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• 2004

The purpose of this research is to establish a concept of the factor of safety of tunnels which is a quantitative estimate of the stability of tunnels. Based on this concept, a numerical technique which calculates the factor of safety of tunnels was developed. To obtain the safety factor of a tunnel, the strength reduction technique in which a series of analyses are repeated with reduced ground strength until the tunnel collapses were employed. With this technique, the failure plane, as well as the factor of safety, can be obtained without prescribing the trial failure plane. Analyses were conducted with FLA $C^{2D}$(ver3.3), a geotechnical analysis program which is based on the finite difference method. From the result, the location of plastic zones, the maximum convergence and the maximum stress generated in the support system were also analyzed. The result shows that factors of safety are higher for the 1st and 2nd rock classes, and lower for the lower rock classes. Furthermore, factor of safety is higher when $K_{0}$ =0.5 compared to at in case of $K_{0}$ =2.0. Through this research, it is found that the factor of safety defined in this research can be used as a good quantitative index representing the stability of tunnels. Also, close examination of the results can help adjustment of the quantity and location of additional supports.s.

• Korean Journal of Agricultural Science
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• v.23 no.1
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• pp.25-38
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• 1996

To investigate the stability problem of irrigation-drainage channel excavation slope on soft ground, analyzed the behavior of the soft ground with excavation slope by the limit equilibrium method and the finite element method, and compared with field tests. The results of this study were summarized as follows; 1. When rapid drawdown the water level, the crack was occurred by the effect of the excess pore water pressure, and the pore water pressure was decreased slowly. 2. As the width of excavation was larger, the crack width was larger. And, excavated depth was deeper, the progressive failure was appeared. 3. When the soft ground excavation was small-scale, the minimum safety factor was more effected by cohesion(1.0, 1.5, 2.0, 2.5, 3.0) than excavated slope inclination(1:l, 1:1.5, 1:2). 4. As excavation was progressed, the settlement occurred on the top-slope due to plastic domain, and heaving was occurred at the bottom of excavation. 5. The maximum shear stress was appeared greatly as the base part of slope went down. Because of the increase of the maximum shear stress, tension area occurred and local failure possibility was increased. 6. As the excavation depth was increased, the maximum shear strain was appeared greatly at the base of slope and distribution pattern was concentrated beneath the middle of slope.

• Korean Journal of Agricultural Science
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• v.23 no.1
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• pp.13-24
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• 1996

The following results were obtained by analyzing the displacement, strain and stability of ground at the soft ground excavation using sheet pile. 1. Before setting the strut, the horizontal displacement was large on the upper part of excavated side, but after setting the strut, it showed concentrated phenomenon while being moved to go down to the excavated side. 2. After setting the strut, the displacement of sheet pile was rapidly decreased about a half compared with before setting the strut. The limitation of excavation depth was shown approximately GL-8m after setting double stair strut. 3. Maximum shear strain was gradually increased with depth of excavation, and local failure possibility due to shear deformation at the bottom of excavation was decreased by reinforcement of strut. 4. Maximum horizontal displacement of sheet pile at GL-7.5m was shown 0.2% of excavation depth in elasto-plastic method, and 0.6% in finite-element methods, and the maximum displacement was occurred around the bottom of excavation. 5. To secure the safety factor about penetration depth in the ground of modeling, D/H should be more than 0.89 in the case of one stair strut, and more than 0.77 in the case of double stair strut. 6. The relation of safety factor and D/H about the penetration depth was appeared, Fs=0.736(D/H) + 0.54 in the case of one stair strut, and Fs=0.750(D/H) + 0.62 in the case of double stair strut.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.54-62
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• 2017

This paper describes the behavior and failure probability of the basic structural members in a fire for the fire safety assessment of offshore structures. A fire safety assessment can be accomplished by comparing the fire resistance of the members with the fire severity of the heat load due to fire. The fire severity is represented as the maximum temperature of the members using the Eurocode 1 standard fire curve and heat transfer equation. On the other hand, the fire resistance is the limiting temperature calculated by a simplified formula in the case of simple structural members. Considering the complexity of FPSOs and offshore structures, a general-purpose structural analysis program should be used and the limiting temperature obtained by analyzing the structural strength of the members through an elasto-plastic analysis with a large deflection, and compared with the maximum temperature. Also, the equality of these two methods of evaluating the fire resistance was confirmed by comparing them. Following three criteria, the strength, serviceability and stability, three failure modes, namely the first failure of a hinge, large deflection and buckling, were chosen. The failure temperature was verified for each failure mode. using the AFOSM method in the equation of the fire severity and fire resistance, thereby giving the failure probability of the member. By applying these processes to the example of a beam and plate, the behavior of the structure and failure (temperature?) of each failure mode can be determined.

• Applied Chemistry for Engineering
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• v.4 no.1
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• pp.196-203
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• 1993

Emulsions were prepared with the inversion emulsification method which adopted the agent-in-oil method-dissolving the mixed surfactants composed of the glycerin monostearate, polyoxyethylene(100) monostearate, and polyoxyethylene(20) sorbitan monostearate into mixtures of liquid paraffin and beeswax, and adding the aqueous solution of propylene glycol, gradually-and then their phases and viscosities behaviors in the emulsifying process were investigated. The fine and homogeneous o/w emulsions were formed in the HLB region (HLB 10.1~12.3), showing liquid crystalline phase and white gel phase in the emulsifying process. The phase inversion steps in the emulsifying process appeared as follows, i.e., oil continuous phase${\rightarrow}$liquid crystalline phase${\rightarrow}$white gel phase${\rightarrow}$o/w emulsion. Shear rate-shear stress curves of the prepared emulsions had the yield values which pointed out the existence of inner structure between emulsion particles, and the hysteresis loop which showed that the inner structure wasbroken irreversibly by the shear. The area of hystersis loop, an index of breakdown of inner structure, was increased with the decreasing of the HLB value of emulsifier, Shear time-shear stress curves showed the time dependence of plastic viscosity, and the relaxation time in time thinning behavior(${\lambda}$) indicated that the stability of emulsions prepared with the inversion emulsification method was decreased with the increasing of HLB values of emulsifier and was higher than that of emulsions prepared by homomixer.