• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 2002.05a
• /
• pp.56-56
• /
• 2002

제지산업의 발전에 따라 치환도가 다른 여러 가지 용도의 양성 전분이 개발되어 적 용되고 있다. 특히 보류제로서 양성전분을 사용할 경우 보류 향상과 더불어 강도개선 효과를 동시에 얻을 수 있는 이점을 지니고 었다. 하지만 용수 조건의 악화, 미세분 함 량의 증가 등과 같은 점차 열악해지는 초지공정에 적용하기 위해서는 보다 높은 치환 도의 전분이 요구 되고 있다. 이에 본 연구에서는 고치환 양성 전분이 초지계 내에 첨가되었올 경우 나타나는 홉 착 특성을 파악하고, 보류 및 탈수 성능을 평가함으로서 올바른 적용 방법을 제시하고 적용 효율의 극대화를 모색하고자 하였다. 산-염기 세척과정을 거쳐 제조한 활엽수 BKP를 이용해 지료를 조성하고, DDA

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.57-60
• /
• 2005

The objective of this paper is to investigate and analyze the behaviour of prestressed I section structural members constructed with ultra high perfomance steel fiber reinforced cementitious concrete (SFR-UHPC). This material is known as reactive powder concrete (RPC) mixed with domestic materials and its compressive strength is over 150MP. The parameters of test specimens were span to depth ratio, prestressing force, prestressing wire placement and web width. Most influential parameter to determine the failure mode between shear and flexural action was proved to be shear span ratio. The characteristics of ultra high-strength concrete is basically brittle, but due to the steel fiber reinforcement behaviour of this structure member became ductile after the peak load. As a result of the test, the stress block of compressive zone should be redefined. The proposed analytical calculation of internal force capacity based by plastic analysis gave a good prediction for the shear and flexural strength of specimens. The numerical verification of the finite element model which constitutive law developed for Mode I fracture of fiber reinforced concrete correctly captured the overall behaviour of the specimens tested.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.5
• /
• pp.1190-1201
• /
• 1995

Photoelastic experiment has been restricted by three significant problems such as the problems of modeling for a complicated body, of development of experimental model material, and of residual stress in photoelastic specimen. The residual stress in photoelastic model materials is caused by molding, cutting and time effects, etc.. Especially, large residual stress exists on the interface of photoelastic model material for bi-material. Small residual stress occurred in the photoelastic model materials is usually neglected in the photoelastic experiments. But the residual stress provides some errors in the results of photoelastic experiments. In this paper, the stress optic law which can be effectively applied to the phtoelastic model materials with residual stress is developed. By using this stress optic law, we can obtain good results from isochromatic fringe patterns of photoelastic experiment specimen in which residual stress are involved. The stress optic law can be applied to obtain good results of photoelastic experiment from composite materials or bimaterials.

• Journal of Periodontal and Implant Science
• /
• v.26 no.1
• /
• pp.68-79
• /
• 1996

To investigate the efficiency of a fibrous collagen membrane(FCM) composed of bovine skin type I atelocollagen as a carrier for BMP, partially purified bovine BMP/FCM($0.3mg/10{\times}5{\times}1mm$) composites were implanted into the dorsal subcutaneous tissue of rats. FCM alone was also implanted as a control. The implants were harvested at 1, 2, 3, and 10 weeks after implantation, then prepared for routine light microscopic observation. The FCM alone did not induce osteogenesis and revealed no specific foreign body reaction nor was there any definite resorptive evidence for 10 weeks after implantation, while the BMP/FCM composites induced favorable bone formation in a process that resembled an endochondral and direct ossification mode. At 10 weeks, the well formed bone confined to embedded collagen fibers revealed hematopoietic marrow between bony trabeculae without evidence of resorptive or degenerative changes . These findings support the suggestion that BMP may induce undifferentiated mesenchymal cells into either chondroblasts or osteoblasts or both independantly according to the chemico- physical characteristics of the carrier, which develops the endochondral and/or direct bone formation process, and suggest that the FCM may be a favorable carrier for BMP.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.3 no.1
• /
• pp.11-19
• /
• 2001

The purpose of this study is to improve the problems in Umbrella Arch Method, such as the oxidation, the difficulties in installation and cutting of the steel pipe. The applicability of the high strength FRP (Fiber-Reinforced-Plastic) materials composed of glass fiber as a substitute of steel pipe was investigated in this study. The results of this study show that FRP material is better than steel pipe in work performance and the durability of material except for its price. From the numerical analysis with various types of FRP, it was evaluated that the equiangular curve type is more efficient than the flat type developed abroad, and the supporting effect of FRP-grout mixture is similar to that of steel-grout mixture in results of bending strength test.

• KSBB Journal
• /
• v.15 no.2
• /
• pp.214-218
• /
• 2000

A hepatitis B Surface Antigen(HBsAg)-screening kit using immunochromatographic assay(ICA) method was developed by e employing two kinds of antibodies. One is mouse monoclonal anti-HBs for tracer antibody and the other is goat p이yclonal a anti-HBs for capture antibody. This capture antibody was immobilized on the surface of nitroceliulose(NC) membrane and the t tracer antibody was conjugated with g미d particles. When serum sample was added to the sample well, the $\infty$njugates d deposited in a dry state on the surface of glass fiber filter were reconstituted and then combined with HBsAg in serum. In 5 5 min after adding, the assay result was visible through the window, that is, the complexes composed of HBsAg and the c conjugates appeared as maroon line on the lower part of the NC membrane. The detection limit of the ICA kit was 2 ng/ml w when being tested with the reference HBsAg.

• Journal of the Korean Wood Science and Technology
• /
• v.27 no.1
• /
• pp.18-23
• /
• 1999

The formation conditions of Na-cellulose II with three fold helix were investigated by an x-ray diffraction method. Na-cellulose II was formed through Na-cellulose I. It seems that the concentration of sodium hydroxide in Na-cellulose II is higher than both those of Na-cellulose I and Na-cellulose III. Na-cellulose II was formed well by different rinsing and drying methods even though the sample treatment was carried out in very short periods of time. Metal-complexed Na-cellulose swollen in the mixture of $Cu(OH)_2$ and sodium hydroxide is stable in wet state, and changed to a different polymorph by drying.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.569-569
• /
• 2012

탄소나노튜브(carbon nanotubes)의 우수한 전기적, 물리적 특성으로 인해 트랜지스터, 태양전지, 고감도 센서, 나노 섬유, 고분자-탄소나노튜브 고기능 복합체 등 다양한 분야에서 이를 응용하려는 노력이 활발히 진행되고 있다. 흥미롭게도 탄소나노튜브는 구조적인 특성 (직경, 밀도, 벽의 수)에 따라 각기 다른 비표면적, 열 전도성, 전기 전도성, 접촉각, 전계방출 특성을 지닌다고 보고되고 있다. 따라서 다양한 분야의 응용을 위해서는 구조적인 특성 제어가 핵심적인 요소라고 할 수 있다. 본 연구에서는 열화학기상증착법(thermal chemical vapor deposition)을 이용하여 수직 정렬된 탄소나노튜브를 합성 하였다. 합성과정에서 압력의 변화가 탄소나노튜브의 밀도와 길이에 큰 영향을 미친다는 것을 확인하였고, 이러한 현상을 이해하기 위해 두 가지의 가능성을 고려하였다. 첫째는 압력의 변화에 따른 촉매의 형성 변화 가능성이며, 둘째는 탄화수소가스의 유입양의 변화에 따른 영향이다. 분석 결과, 동일한 압력에서 탄화수소가스의 부분압을 변화시켜 실험한 결과로부터 탄화수소의 유입양의 변화가 합성된 탄소나노튜브의 밀도에 큰 영향을 미치고 밀도가 높은 경우 길이가 긴 탄소나노튜브가 합성되는 것을 확인할 수 있었다.

• Journal of the Korean Ceramic Society
• /
• v.34 no.7
• /
• pp.758-766
• /
• 1997

Non-brittle fracture behaviour of the two composite structures made of two different brittle materials was investigated using 3-point bending test. First, the layered and fibrous macro-composites were fabricated using the material easily formed, yet showing a brittle fracture behaviour similar to ceramics. The layered and fibrous Al2O3 /Al2O3 composites with weak interface were also fabricated using plate of 2 mm thickness and rod of 3 mm diameter respectively. Comparison of the mechanical properties between these two structures was performed in the lights of flexural strength and work of fracture for the composites consisting of Al2O3 and simulated materials respectively. The strength ratio of layered structure to the monolith of same volume was 0.6 and the ratio of fibrous one was about 0.2 for the composites made of simulated brittle material. The ratio of the work of fracture of the fibrous to the layered was 0.47. For Al2O3/Al2O3 composites, the strength ratio of layered and fibrous structures to the monolith with same volume were about 0.6 and 0.2 respectively. The ratio of work of fracture of the fibrous to the layered was 0.6. These confirmed that the layered structure was superior to the fibrous one in terms of flexural strength and work of fracture.

• Polymer(Korea)
• /
• v.38 no.6
• /
• pp.726-734
• /
• 2014

Three different types of additives, thiokol, epoxidized natural rubber (ENR) and epoxidized linseed oil (ELO), were dispersed in an epoxy matrix before being used in glass fiber (GF) composites, and their effects on the mechanical and dielectric properties of epoxy resin and glass fiber reinforced epoxy composites (GF/EP) were examined. The addition of each of 7 phr ENR, 9 phr ELO and 5 phr thiokol into the epoxy resin increased the fracture toughness significantly by 56.9, 43.1, and 80.0%, respectively, compared to the unmodified resin. The mode I interlaminar fracture toughness of the GF/EP at propagation was also improved by 26.9, 18.3 and 32.7% when each of 7 phr ENR, 9 phr ELO, and 5 phr thiokol, respectively, was dispersed in the epoxy matrix. Scanning electron microscopy showed that the additives reduced crack growth in the GF/EP, whereas their dielectric measurements showed that all these additives had no additional effect on the real permittivity and loss factor of the GF/EP.