• Journal of Periodontal and Implant Science
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• 제52권2호
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• pp.155-169
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• 2022

Purpose: The aim of this study was to determine the effect of insulin growth factor binding protein-3 (IGFBP-3) on the inhibition of glucose oxidative stress and promotion of bone formation near the implant site in a rat model of methylglyoxal (MGO)-induced bone loss. Methods: An in vitro study was performed in MC3T3 E1 cells treated with chitosan gold nanoparticles (Ch-GNPs) conjugated with IGFBP-3 cDNA followed by MGO. An in vivo study was conducted in a rat model induced by MGO administration after the insertion of a dental implant coated with IGFBP-3. Results: MGO treatment downregulated molecules involved in osteogenic differentiation and bone formation in MC3T3 E1 cells and influenced the bone mineral density and bone volume of the femur and alveolar bone. In contrast, IGFBP-3 inhibited oxidative stress and inflammation and enhanced osteogenesis in MGO-treated MC3T3 E1 cells. In addition, IGFBP-3 promoted bone formation by reducing inflammatory proteins in MGO-administered rats. The application of Ch-GNPs conjugated with IGFBP-3 as a coating of titanium implants enhanced osteogenesis and the osseointegration of dental implants. Conclusions: This study demonstrated that IGFBP-3 could be applied as a therapeutic component in dental implants to promote the osseointegration of dental implants in patients with diabetes, which affects MGO levels.

• 한국지반공학회논문집
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• 제25권10호
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• pp.77-85
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• 2009

본 논문은 점성토에 시공된 트윈 병렬 터널로 인해 발생된 지반변형을 연구하기 위해 시행된 1g 모형실험의 과정 및 결과에 대해 기술한다. 트윈 병렬 터널 시공 시, 터널 2(후행터널)로 인한 지반침하는 터널 1(선행터널)로 인한 지반침하와 다른 양상을 보였다. 그 양상은 지반손실의 증가, 침하 폭의 증가, 최대침하의 증가 및 최대침하 위치의 이동으로 요약된다. 따라서 터널 2로 인한 지반침하를 예측하기 위해 기존 Gaussian curve방법을 이용하는 것은 적절치 못하다. 이에 본 논문은 터널 2로 인한 지반침하 예측 개선을 위해 새로운 지반침하 예측 방법(Modification factor방법)을 소개한다. 본 논문은 Modification factor 방법의 실대형 현장 상황 적용을 위한 파라미터 선택에 대해 기술하며, 또한 그 적용 한계에 대해 토의한다.

• 대한토목학회논문집
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• 제28권5D호
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• pp.665-675
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• 2008

본 연구는 터널공사를 대상으로 사업 초기단계에서 터널공사의 설계 대안에 대한 공사비를 신속히 추정하고, 사업이 진행되면서 상황변화에 따른 사업비 측면에서의 영향을 파악할 수 있도록 함으로써, 적정한 의사결정을 지원하기 위한 개략적 터널공사비 추정모델 제시를 목적으로 한다. 이를 위해 터널공사의 수행에 있어 공사비에 영향을 미치는 요인을 분석하고, 공사비 영향요인별 공사비 변화의 정도를 분석하였다. 공사비 영향요인은 천공방식, 굴착방법, 기폭장치, 적재장비 용량, 버력의 단위중량 및 토량환산계수, 터널 연장을 포함하는 7개의 요인을 대상으로 하여 각 영향요인의 변화에 따른 공사비 변동 크기를 분석하였다. 분석결과는 기획단계에서 사업의 기본적인 조건을 바탕으로 사업비를 추정하고, 설계 및 시공단계에서 설계 대안에 대한 공사비의 영향을 효율적으로 평가하는데 필요한 공사비 추정모델의 구축을 위한 기초정보를 제공할 것으로 기대된다.

• Journal of Information Processing Systems
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• 제8권1호
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• pp.55-66
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• 2012

This paper presents a dual modeling method that simulates the graphic and haptic behavior of a volumetric deformable object and conveys the behavior to a human operator. Although conventional modeling methods (a mass-spring model and a finite element method) are suitable for the real-time computation of an object's deformation, it is not easy to compute the haptic behavior of a volumetric deformable object with the conventional modeling method in real-time (within a 1kHz) due to a computational burden. Previously, we proposed a fast volume haptic rendering method based on the S-chain model that can compute the deformation of a volumetric non-rigid object and its haptic feedback in real-time. When the S-chain model represents the object, the haptic feeling is realistic, whereas the graphical results of the deformed shape look linear. In order to improve the graphic and haptic behavior at the same time, we propose a dual modeling framework in which a volumetric haptic model and a surface graphical model coexist. In order to inspect the graphic and haptic behavior of objects represented by the proposed dual model, experiments are conducted with volumetric objects consisting of about 20,000 nodes at a haptic update rate of 1000Hz and a graphic update rate of 30Hz. We also conduct human factor studies to show that the haptic and graphic behavior from our model is realistic. Our experiments verify that our model provides a realistic haptic and graphic feeling to users in real-time.

• Composites Research
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• 제13권1호
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• pp.50-60
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• 2000

본 연구는 섬유/입자 혼합금속복합재료의 강화기구를 분석하는 이론적 해석방법을 제시하였다. 혼합금속복합재료의 인장강도 및 탄성계수는 같은 보강재의 부피분율 가진 단섬유복합재료에 비해서 강도가 최대 20%까지 증가한다. 이러한 증가효과는 본 연구에서 새로이 제안된 클러스터 모델을 도입한 후 이에 따른 강화효과를 Modified Rule of Mixture을 적용하여 분석하였다. 해석결과 클러터구조는 인장강도에 대해서 섬유의 효율을 탄성계수에 대해서는 배향인자를 증가시키는 것으로 나타났다. 이론적 해석 결과는 $Al_2O_3$섬유/입자 예비성형체에 AC8A를 침투시켜 제조한 금속복합재료에 대한 실험결과와 비교되었으며 이를 통해 해석이론이 타당함을 확인하였다.

• Carbon letters
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• 제14권1호
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• pp.14-21
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• 2013

Physically and chemically activated carbons (ACs) exhibited high adsorption capacities for organic and inorganic pollutants compared with other adsorbents due to their expanded surface areas and wide pore volume distribution. In this work, seven steam-ACs with different burn-off have been prepared from cotton stalks. The textural properties of these sorbents were determined using nitrogen adsorption at $-196^{\circ}C$. The chemistry of the surface of the present sorbents was characterized by determining the surface functional C-O groups using Fourier transform infrared spectroscopy, surface pH, $pH_{pzc}$, and Boehm's acid-base neutralization method. The textural properties and the morphology of the sorbent surface depend on the percentage of burn-off. The surface acidity and surface basicity are related to the burn-off percentage. A theoretical model was developed to find a mathematical expression that relates the % burn-off to ash content, surface area, and mean pore radius. Also, the chemistry of the carbon surface is related to the % burn-off. A mathematical expression was proposed where % burn-off was taken as an independent factor and the other variable as a dependent factor. This expression allows the choice of the value of % burn-off with required steam-AC properties.

• 한국주거학회논문집
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• 제22권6호
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• pp.51-60
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• 2011

The maintenance cost depends on various factors such as building volume, floor area, number of household and so on. The maintenance cost of the apartment housing is affected by the maintenance type, building physical factor, sociogeographic aspects. Among these, the maintenance characteristics is represented and made up by the total floor area and number of household which means main factor to provide the building scale roughly. In this paper, it aimed at modelling the estimation function of the maintenance cost with the total floor area and number of household and analyzing the elasticity of the two factors. Although items of maintenance cost are various in general cost, repair cost and so on, we classified these items into the 5 categories. 5 categories are a general cost, a facility maintenance cost, a utilization cost, insurance and sanitary cost. The estimation function used a power function and it has better goodness-offitness than any other estimation methods in statistics. A power function has a three curve types with concave and convex and linear style to the origin.

• 대한기계학회논문집B
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• 제21권1호
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• pp.49-56
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• 1997

Heat-transfer enhancement is seeked through modifications of fin surface. Real life plate-fin heat exchangers have complex three-dimensional geometries. Fins can have arrays of dimples and are attached to rows of penetrating tubes. To isolate the effect of surface modification, we model the real flow by a two-dimensional channel flow with a dimple on one side. The flow is analysed by solving the incompressible Navier-Stokes equation by a finite volume method on a generalized boundary-fitted coordinate. Results show a trapped vortex inside the dimple for all cases computed. Local maximum of Nusselt number occurs near the downstream end of the dimple, due to such a vortex. Location of the vortex does not change with respect to the wall temperature change, but moved downstream when Reynolds number increases. This, together with the results that in all cases vortex core is somewhat downstream of the dimple center, suggests that the mean flow above continuously feeds the kinetic energy to the recirculating flow. Heat transfer enhancement and pressure losses are studied through analysing the relevant dimensionless parameters like, Nusselt number and friction factor. In all cases computed, dimpled channel flow experiences less pressure loss than two-dimensional Poiseuille flow.

• Geomechanics and Engineering
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• 제19권2호
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• pp.153-165
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• 2019

A case study of monitoring and analysis of surface settlement induced by tunneling of Tabriz metro line 2 (TML2) is presented in this paper. The TML2 single tunnel has been excavated using earth pressure balanced TBM with a cutting-wheel diameter of 9.49 m since 2015. Presented measurements of surface settlements, were collected during the construction of western part of the project (between west depot and S02 station) where the tunnel was being excavated in sand and silt, below the water table and at an average axis depth of about 16 m. Settlement readings were back-analyzed using Gaussian formula, both in longitudinal and transversal directions, in order to estimate volume loss and settlement trough width factor. In addition to settlements, face support and tail grouting pressures were monitored, providing a comprehensive description of the EPB performance. Using the gap model, volume loss prediction was carried out. Also, COB empirical method for determination of the face pressure was employed in order to compare with field monitored data. Likewise, FE simulation was used in various sections employing the code Simulia ABAQUS, to investigate the efficiency of numerical modelling for the estimating of the tunneling induced-surface settlements under such a geotechnical condition. In this regard, the main aspects of a mechanized excavation were simulated. For the studied sections, numerical simulation is not capable of reproducing the high values of in-situ-measured surface settlements, applying Mohr-Coulomb constitutive law for soil. Based on results, for the mentioned case study, the range of estimated volume loss mostly varies from 0.2% to 0.7%, having an average value of 0.45%.

• 한국미생물·생명공학회지
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• 제17권3호
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• pp.173-177
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• 1989

HeLa 세포주의 연속 배양시 세포수가 배지의 이동속도가 증가함에 따라 감소하는 현상을 나타냈으며, 최대 세포수를 유지할 때의 dilution rate은 0.012(1/h)로 wash-out인 0.050(1/h)보다 극히 낮으며, dilution rate이 0.030(1/h)일 때 2.0(mL of cells/L/h)의 최대 세포 생산속도를 보였다. 또한 낮은 배지 이동속도에서 세포수의 감소에 따른 maintenance term의 존재를 확인했다. 더불어 packed cell volume파 산소소비속도의 측정값이 실제 세포증식과 밀접한 관계가 있음이 입증되어 간접방법에 의한 생육도치 측정이 가능하게 되었다. 또한 산소 yield model에 의해 최대 산소 수율, $Y_{O2}^{max}$과 maintenance 산소소비속도, m$_{O2}$가 각각 4.1$\times$$10^5$(cells/mmole $O_2$)와 10.71$\times$$10^{-9}$(mmole $O_2$/ cells/h)로 측정되었다.