• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.46.2-46.2
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• 2009

In vitro 상에서 골조직을 원활하게 재생하기 위해서는 3차원 지지체를 이용한 세포 배양과 세포 배양 시 세포의 형태와 기능을 유지/향상시키기 위한 인체 내 미세 환경 재현은 필수적이다. 따라서 본 연구에서는 뼈 성분과 유사한 생체 활성 물질인 hydroxyapatite (HA)와 생분해성 고분자인 poly $\varepsilon$-caprolactone (PCL)를 복합재료로 이용하여 내부 연결성이 우수한 골조직 재생용 3차원 지지체를 제작하였으며, 골 재생 능력 향상을 위하여 인체내 골조직의 기계적 미세 환경을 체외에서 구현한 새로운 형태의 perfusion bioreactor system을 개발/적용하였다. 또한 본 연구에서 개발된 perfusion bioreactor system의 생물학적 평가를 위해 MG63 (osteoblast like cell, 한국 세포주 은행)과 New Zealand White Rabbit에서 분리한 중간엽 줄기세포를 골조직 재생용 3차원 지지체에 파종하였다. 48시간 동안 안정화 후 perfusion bioreactor system을 이용하여 기계적 자극을 파종된 세포에 인가하였으며, 배양 기간 동안 세포의 증식 확인 및 형태학적 관찰을 실시하였다. 본 연구 결과, perfusion bioreactor system을 이용하여 기계적 자극을 인가한 실험군에서 세포의 증식 및 활성도가 대조군에 비해 우수함을 확인 할 수 있었다. 따라서, perfusion bioreactor를 이용한 세포 배양은 세포의 활성 향상 및 골조직 재생에 도움이 될 것으로 사료된다. 차후 perfusion bioreactor를 이용한 다양한 패턴의 자극이 골재생 능력 및 중간엽 줄기세포의 골 분화능에 미치는 영향에 대한 연구가 필요할 것으로 사료된다.

• Elastomers and Composites
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• v.47 no.4
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• pp.272-281
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• 2012

Flexible/stretchable electronics have recently focused, since their applications extend to emerging flexible displays, sensors, dielectric elastomer actuator and generators, and smart surgical tools. Flexible/stretchable electrodes should be synchronized with employing mechanical deformations of either flexing or stretching modes. Thus, the research area is one of the tough subjects, since the electrodes should keep their basic functions of electrodes under various mode of mechanical deformations. In this review, we discuss the recent development in the preparation and properties of such flexible/stretchable electrodes.

• Elastomers and Composites
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• v.45 no.1
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• pp.44-50
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• 2010

The butadiene rubber(BR) blends with chloroprene rubber(CR) were prepared by mechanical mixing method. Cure characteristics, mechanical properties, ozone resistance properties and dynamic mechanical properties were subsequently examined. The properties of ozone resistance of pure BR was significantly improved through blending with 50 wt% CR. Dynamic characteristics determined from a Rheovibron generally showed two glass transition($T_g$) for the entire blends, $tan{\delta}$ peak monotonically shifted toward the higher temperature with the increasing content of CR. Optimum cure time of compound was significantly lengthened with loading of CR.

• Annual Conference on Human and Language Technology
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• 1993.10a
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• pp.437-447
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• 1993

국제 협약에 따라 한글에 관한 정보는 로마자로 표기해야 한다. 우리나라는 1959년 2월 로마자 표기법'을 제정, 수차례 개정을 통해 1983년 6월 문교부(Ministry Of Education)안을 발표했으나, 표지판, 역명, 교과서, 공공문서들에서 활용되었지만, 영자신문, 외국 학술지등은 M-R( Mccune-Reishauer ) 표기법을, 인명, 신문 및 방송매체 등은 혼합표기방식을 사용함으로써 인(人). 지명(地名), ID, 대표어등 정보 검색시 혼란을 야기시켰고, 개정안에 따를 표기 정정으로 수백억원에 가까운 예산을 낭비하였으며, 최근 ISO(International Standard Organization)에서는 남북한 단일화 및 기계적 변환을 요구하고 있으나, 반달표 표기곤란, 편리성 결여, 북한의 주장등의 사유로 제정등을 거론하고 있는 실정에 있다. 잘 쓰지 않는 ASCII 코드 중에서 반달점 폰트를 제작하고 단어, 문장, 문서를 STRING으로 받아 알고리즘화된 음운법칙을 적용하여 소리글자로 변환하고 MOE테이블에서 대응글자를 참조하여 기계적 변환이 가능하도록 하였으며, 세련된 디자인, 풀다운 팝업방식을 채택, 2HD 1장으로 국내최초로 개발하였다.

• Journal of the Korean GEO-environmental Society
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• v.7 no.2
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• pp.43-53
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• 2006

Hydraulic fracturing is an important and abundant process in both industrial applications and natural environments. The formation of hydraulic fractures includes nucleation, growth, and termination in numerous rock types and stress regimes, at scales ranging from microns to many kilometers. As a result, fracture segmentation, commonly observed at all scales and in all geo-materials, contributes to this complexity in many ways. In particular, the mechanical interaction of fracture segments strongly affect almost all hydraulic fracturing processes. In this paper, the segmented fracture opening deformation in rock by hydraulic fracturing is quantified using boundary collocation method and is compared with non-interacting single fracture.

• Journal of the Society of Disaster Information
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• v.7 no.1
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• pp.32-42
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• 2011

Many researches have been conducted to evaluate the performance of modified asphalt concrete mixtures. The research was conducted to estimate the laboratory mechanical characteristics of Elvaloy-modified asphalt concrete mixture. To achieve its intended objective, indirect tensile test and resilient modulus test were performed. The rest results revealed that indirect tensile strengths and resilient moduli of the Elvaloy-modified asphalt concrete mixture were higher than those of the conventional dense-graded. As a result, within the limits of the tests conducted in this research, it is predicted that the performance and stability of the Elvaloy-modified asphalt concrete mixture are better than that of the conventional dense-graded one.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1453-1458
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• 2009

This study is to apply the mechanical press joining method to join two kinds of sheet metals with circular holes by mechanical pressing instead of laser beam. Usage of the mechanical pressing avoids the thermal deformation of sheet metals which occurs inevitably in laser joining. A die design has been proposed to make the mechanical press joining applicable with finite element analysis. Five design factors related to the joining force have been selected and applied to the Taguchi method for optimization. Among five factors, 'Forming Depth' and 'Punch Corner Radius' have been revealed to be the most influential ones.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.787-794
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• 2010

This paper aims to evaluate the effect of each material ingredient on mechanical and dynamic performance and to determine an optimal mixing condition of a rubber granule layer. To minimize the required number of tests, the test matrix was established by using the design of experiments (DOE). The tensile tests were then performed to identify the mechanical properties. Also, to evaluate the dynamic performance that the IAAF has required for athletics tracks for athletes' safety and balance, a series of impact tests were performed by using the so-called the "artificial athlete" machine. Finally, the response surface methodology was used to decide the optimal mixing conditions needed to achieve a high level of mechanical properties and dynamic performance.

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.1
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• pp.57-62
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• 2019

In this paper, oneM2M based data monitoring and acquisition system is designed and implemented to measure and transmit the voltage, current, temperature, acceleration and vibration of the motor. The proposed system can detect electrical faults (overcurrent, reverse phase, phase loss, ground fault) and mechanical faults (MC counter, motor operation time, bearing and winding temperature, motor speed, insulation resistance). The system consists of sensor data collection, web server, php, database, wired/wireless communication system. The insulation resistance and the motor speed were measured, and the experimental results were similar for both the test resistance value and the reference input value.

• Resources Recycling
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• v.7 no.3
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• pp.42-51
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• 1998

Hydrogen in atmosphere can easily dissolve in melt of light metal alloys. Increasing demand for recycling of light metal a alloys has, therefore, focused attention on the removal of hydrogen gas, and alloy addition in melt has become an imporLant r refining process. For this purpose behaviors of mixing and hydrogen degassing in impeller agitated refming vessel with/without barnes were investigated. Flow patterns, mixing time behavior and kinetics of degassing in various agitating conditions were analysed in watet model experiments. And, numerical analysis on turbulent flow pattern in impeller agitated vessels was performed.