• Economic and Environmental Geology
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• v.30 no.4
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• pp.303-312
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• 1997

The massive, fractured and porous-type of glauconite, which is subdivided by surface morphology, occur in subtidal sand and semiconsolidated intertidal sand/mud from continental shelf of the southeastern Yellow Sea. This area is presumed to be a part of Holocene transgressive tidal systems tract. The glauconite, pellet-like grains with diameter of 0.1 to 1 mm, is scattered in surface sand sediments. Results of X-ray diffraction data of the minerals are monoclinic with $a=5.242{\AA}$, $b=9.059{\AA}$, $c=10.163{\AA}$, ${\beta}=100.5^{\circ}$, $V=474.53{\AA}^3$. Thermal treatments on the oriented glauconite increase the X-ray diffraction intensity near $10{\AA}$ (001), suggesting the presence of some expandable layers. Specific gravity of the glauconite is $2.60{\pm}0.45gm/cc$ on the basis of chemical composition and unit-cell dimensions. Based on $O_{10}(OH)_2$, chemical composition of glauconites, octahedral Fe content ranges from 1.19 to 2.06 atoms, corresponding octahedral AI is 0.18 to 0.76 atoms, which progressively substitute Fe for AI with increasing from porous to massive-type. The Mg content ranges from 0.35 to 0.54 atoms, and shows higher with increasing Al contents. A systematic increase of interlayer K from 0.34 to 0.71 is also observed with apparent increases from porous to massive-type, and related to a proportion of expandable layers. The clay preserved in glauconite, which is recognized as ordered/disordered (massive to fractured-type). The interstratified illite/smectite (porous-type), contains 7 to 27 % expandable layers. The glauconite seems to originate from post depositional authigenic growth in reducing environments promoted by the dissolution of clay minerals and biogenic debris.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.2
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• pp.241-251
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• 1988

The purpose of this paper is to evaluate fracture strength of WA-vitrified and resinoid bond grinding wheels by means of acoustic emission. The paper conducts tension test, compression test, splitting tensile test and bending test with AE measuring system. These tests have been carried out in accordance with the grain sizes and grades of grinding wheels. The fracture strength of grinding wheels is evaluated by the clarification of biaxal fracture criterion of Babel and Sines. It clarifies the influence of factors of grinding wheel upon AE characteristics and evaluates the predictability of life of grinding wheels and the perception of fracture.

• Electrical & Electronic Materials
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• v.9 no.2
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• pp.146-151
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• 1996

PZT powders were prepared by the molten salt synthesis method. The porous PZT ceramics were made from a mixture of PZT and polyvinylalcohol(PVA) by BURPS(Bumout Plastic Sphere) technique. The 3-3 type composites were fabricated by impregnating an sintered porous PZT ceramics with various polymer matrices. The relative permittivity of 3-3 type composite specimens was shown 860-1,100 smaller than that of solid PZT ceramics(2,100), and the dissipation factors of composite specimens were about 0.02 to 0.03. The piezoelectric coefficient d$_{33}$ of composite specimens(285-328*10$^{12}$ C/N) was comparable with that of single phase PZT specimens(364*10$^{-12}$ C/N). The thickness mode coupling factor k$_{t}$(O.5-0.6) of composite specimens was comparable with that of single phase PZT specimens(k$_{t}$-0.7), and the mechanical quality factor of composite specimens was smaller than 10, and thus these 3-3 type composite specimens would be believed as a good candidates for broad band transducer applications.ons.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2002.05a
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• pp.22-22
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• 2002

본 연구에서는 교량, 발전소, 산엽체의 시설물 둥 대형 옥외 설치 구조물의 부식방지를 위해, 전류 인가형 부식 방지 장치를 개발하였다. 기존의 전극기판(anode base)은 pve로 만들 어져 있어서, 옥외에 설치된 상태에서 쉽게 열화되어 부스러지며, 비 갠 후 시설물의 일부에 물기가 남아 있는 부식 환경하에서도 플라스틱 기판은 물기가 쉽게 제거되어 이마 건조된 상태가 된다. 이 경우에는 기판을 통해 부식방지 전류를 흐르게 할 수가 없기 때문에 희생 양극의 임무를 수행할 수가 없으며, 시설물이 부식되는 단점이 있다. 본 연구에서 개발한 흡습성 기판은 기존의 pve 기판의 단점을 개선한 것으로, 대기 중에 방치해도 수명이 영구적이며, 다공질이기 때문에 흡습성이 있어서 비 캔 후에도 기판 내부와 표면에 물기가 남아 었다. 따라서, 비 캔 후 부식환경에서도 부식 방지 전류를 흐르게 할 수가 있어서 희생양극의 업무를 수행할 수 있다. 본 연구에서는 옥외 구조물에 대한 방식 특성을 평가하기 위하여, 세라믹 기판을 부착하고 전류 측정을 하기 위한 철판(보통탄소강)구조물을 아래와 같이 제작하였다. 구조물의 $가로{\times}세로$ 크기는 $450mm{\times}450mm$ 이며, 구조물의 중앙에 세라믹 또는 pve Anode 기판을 부착 하였다. 살수 후 전류의 측정 위치는 구조물의 Anode 기판 중심에서 100mm 떨어진 지점 4 곳에 부착하였다. 본 연구에서 개발한 세라믹 가판의 경우와 기존의 pve 기판의 경우를 비 교 실험한 결과, 전자의 경우는 120분 경과 후에도 $70~80\mu\textrm{A}$의 많은 양의 전류가 흐르는 것으로 밝혀졌으며, 후자의 경우는 120분이 지난 후에는 전류가 전혀 흐르지 않는 것올 알 수 있다. 따라서, 기존의 pve 보다 세라믹 기판의 경우가 수분 흡수율이 높아 더 오랫동안 전류를 흐르게 하여 방식성이 개선된 것으로 판단된다.

• Journal of Technologic Dentistry
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• v.33 no.4
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• pp.307-312
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• 2011

Purpose: The purpose of this study is a porous cube mechanical analysis for the dental implant. Methods: The porous cube with a side length of 10mm was designed for dental implant. To choose proper design, porous hexagon with a side 10mm which was drilled as a regular hexagon with diameter 0.8mm, 1.0mm, 1.2mm and a side 0.4mm, 0.5mm, 0.6mm each using Computer AUTO CAD(Autodesk, 2008). Each cube was carried out in the mechanical analysis. Results: The result of mechanical analysis was observed that the H0.8 was minimum stress 0.045068MPa, maximum stress 9.4565MPa and minimum strain $0.00389{\times}10^{-4}Mpa$, maximum strain $0.816{\times}10^{-4}Mpa$, the H1.0 minimum stress 0.001147MPa, maximum stress 9.099MPa and minimum strain $0.000099{\times}10^{-4}Mpa$, the maximum strain $0.784{\times}10^{-4}Mpa$, the H1.2 minimum stress 0.099393MPa, maximum stress 13.137MPa and minimum strain $0.0112{\times}10^{-4}Mpa$, maximum strain $1.13{\times}10^{-4}Mpa$. Conclusion: The mechanical analysis of porous hexahedron was that H1.0 is the best result. It will be applicable to the porous implants.

• Journal of Power System Engineering
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• v.14 no.5
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• pp.41-47
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• 2010

티타늄과 티타늄 합금은 재료적 특이성 때문에 심장 혈관 임플란트에서 일반적으로 사용되어 왔다. 일찍이 적용된 예로는 인공심장판막, 심박조율기의 보호케이스, 혈액 순환 장치 등이 있다. 하지만 물질유도혈전증(Material-induced thrombosis)은 혈전폐색에 의해 기인한 기능 손실로 심장혈관 임플란트 장치의 주된 합병증으로 존재하고 있으며, 심장혈관 임플란트의 혈전유전자는 심장혈관장치의 발달에 주된 난관 중 하나로 남아있다. 그리고 텍스처 혈액 접합 물질(Textured blood-contacting material)은 1960년대 초반 이후부터 혈액순환 보조 장치의 임상실험에 사용되고 있다. 접합 물질에 내장된 텍스처 섬유조직 표면은 형성, 성장, 안정적 부착, 생물학적 내벽(neointimal layer) 등 유도 혈액(entrapping blood) 성분에 의해 형성된다. 공동(cavity) 형상의 용해 가능한 미립자를 사용하는 SCPL법(Solvent casting/particulate leaching method)은 티타늄 기질 이전에 형성된 폴리우레탄 위에 텍스처(texture)를 생성하기 위해 사용되었다. 또한 콜라겐의 부동화(不動化)에 의한 공동(cavity)은 혈액 접합면에 잔존하기 위한 내피세포를 고정할 수 있는 효과가 있다. cpTi로 층화된 PU 기소공성(microporous)은 구조적 특성과 혈전증 감소를 위한 생물학적 내벽 사용의 잠재성을 평가하기 위한 세포 공동체 실험을 통해서 평가되었다.

• Journal of the Korean Professional Engineers Association
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• v.16 no.3
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• pp.68-73
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• 1983

The metal deposition behavior in the barrel tin plating has been studied for the electronic DIP products, and tried to find out some modified factors in order to explain partial ,current flow behavior of this load. The deposition distribution characteristics for DTP products should be classified with the normal barrel plating as partially conductive load. Deposit distribution curves obtained from one-dimensional model have shown strong dependence n the applied current density, rotating speed of barrel and metal ion concentration of the solution. Theoretical formula J=$\delta$'/${\beta}$-{-c$^3$/${\gamma}$-exp-(1-${\alpha}$)n${\Phi}$} derived from one-dimensional porous model has been proposed for the barrel plating behavior where higher overpotential and concentration changes take place during barrel plating.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4A
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• pp.237-244
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• 2012

There is mounting recognition among concrete researchers that fiber reinforcement makes up for the inherent weakness in resisting tensile force of structural concrete. In practice of application of the fiber to concrete, however, several problems still remain to solve for assuring a uniform mix quality. The Kagome truss that is widely used in mechanical engineering field seems to be a good replacement for the steel fiber. This paper presents the test results of a pilot study for the concrete members reinforced by Kagome truss which is a periodic cellular metal of wire-woven. Three types of Kagome truss bulk were prefabricated and filled with normal concrete to make small-scaled test beams. The beams reinforced by a normal steel stirrups were also tested up to failure to compare the behavioral results. From the results obtained, it is appeared that comparing with beams reinforced by normal stirrups, the beams reinforced by Kagome truss showed better performance in load carrying capacity as well as ductility. Therefore, the Kagome truss is proved to be a good web shear reinforcing material.

• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1153-1157
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• 2002

The fabrication of a three-layered asymmetric ceramic membrane was performed by slip casting of the porous alumina support and dip coating of the alumina intermediate layer using high purity ${\alpha}-Al_2O_3$ powders that have different particle size, followed by screen printing-pyrolysis of the $Tio_2$ layer as an ultrafilteration membrane using Ti-naphthenate solution. The bending strength, porosity and mean pore size of the alumina support were 231 kg/$cm^2$s, 30.26% and 0.19 ${mu}m$, respectively. The thickness of the intermediate layer was 30 ${mu}m$ and the mean pore size of that was 0.063 ${mu}m$. Also, the top layer was 0.5 ${mu}m$ thick and micropores with about 20 nm size were formed uniformly.

• Journal of the Korean Geotechnical Society
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• v.29 no.1
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• pp.93-107
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• 2013

Thermal conduction of the particulate composites or granular materials can be widely used in porous materials and geotechnical engineering. And it has continued to develop "effective thermal conductivity" of medium by modeling energy relationship among particles in medium. This study focuses on the development of the effective thermal conductivity at the unsaturated conditions of soils using the modified network model approach assisted by synthetic 3D random packed systems (DEM method, Discrete Element Method) at the particle scale. To verify the network model, three kinds of glass beads and the Jumunjin sand are used to obtain experimental values at various unsaturated conditions. The PPE (Pressure Plate Extractor) test is then performed to obtain SWCC (Soil-Water Characteristic Curve) of soil samples. In the modified network model, SWCC is used to adjust the equivalent radius of thermal cylinder at contact area between particles. And cutoff range parameter to define the effective zone is also adjusted according to the SWCC at given conditions. From a series of laboratory tests and the proposed network model, the modified network model which adopts a SWCC shows a good agreement in modeling thermal conductivity of granular soils at given conditions. And an empirical correlation between the fraction of the mean radius (${\chi}$) and thermal conductivity at given saturated condition is provided, which can be used to expect thermal conductivity of the granular soils, to estimate thermal conductivity of granular soils.