• Macromolecular Research
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• 제17권9호
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• pp.703-708
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• 2009

Silk fibroin scaffolds were examined as a biomaterial option for tissue-engineered cartilage-like tissue. In tissue engineering for cartilage repair using a scaffold, initial chondrocyte-material interactions are important for the following cell behaviors. In this study, the surface of nanofibrous silk fibroin (NSF) meshes was modified by a microwave-induced argon plasma treatment in order to improve the cytocompatibility of the meshes used as cartilaginous grafts. In addition, the effects of a plasma treatment on the cellular behavior of chondrocytes on NSF were examined. The plasma treatment resulted in an increase in the hydrophilicity of NSF meshes suggesting that the cytocompatibility of the mesh might be improved. Furthermore, the human articular chondrocytes showed higher viability on the surface-modified NSF meshes. These results suggest that the surface modification of NSF meshes by plasma can enhance the cellular behavior of chondrocytes and may be used in tissue engineering.

• 한국콘텐츠학회논문지
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• 제12권9호
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• pp.182-193
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• 2012

벨소리와 통화연결음 시장의 확대에 주목하여 음원소비가 감상용 음원에서 꾸미기용 음원으로의 활용 확대되는 시점에서 발신자와 수신자가 음원에 대하여 브랜드개성으로 인식하는지, 자아표현이 어떠한 방식으로 이루어 질 것인가에 관한 연구이다. 대학생 196명을 대상으로 본인의 자아이미지와 본인이 선택 혹은 선택 예정인 벨소리와 통화연결음이 일치하는지에 대한 설문조사를 실시하였다. 표본을 대상으로 SPSS 19.0 통계패키지를 사용하여 대응표본 t테스트를 실시한 결과 자아이미지의 요인으로 도출된 내향성, 외향성과 벨소리, 통화연결음의 요인으로 도출된 내향성과 외향성의 관계가 서로 불일치하였다. 즉 내향성을 가진 소비자는 외향적인 음원을, 외향적인 소비자는 내향적인 음원을 선택하고 있었다. 휴대전화 발신자는 벨소리와 통화연결음 등 음원을 선택함에 있어 본인이 아닌 상대방을 염두에 두어 본인의 자아이미지와 상반되는 브랜드개성을 가진 음원을 선택하는 즉 과시적 소비성향을 보여주고 있다.

• International Journal of Oral Biology
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• 제41권2호
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• pp.69-74
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• 2016

Skin-derived precursors (SKPs) have potential to differentiate to various cell types including osteoblasts, adipocytes and neurons. SKPs are a candidate for cell-based therapy since they are easily accessible and have multipotency. Most mammalian cells are exposed to a low oxygen environment with 1 to 5% $O_2$ concentration in vivo, while 21% $O_2$ concentration is common in in vitro culture. The difference between in vitro and in vivo $O_2$ concentration may affect to the behavior of cultured cells. In this report, we investigated the effect of hypoxic condition on stemness and proliferation of SKPs. The results indicated that SKPs exposed to hypoxic condition for 5 days showed no change in proliferation. In terms of mRNA expression, hypoxia maintained expression of stemness markers; whereas, oncogenes, such as Klf4 and c-Myc, were downregulated, and the expression of Nestin, related to cancer migration, was also downregulated. Thus, SKPs cultured in hypoxia may reduce the risk of cancer in SKP cell-based therapy.

• 한국연소학회지
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• 제16권2호
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• pp.23-32
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• 2011

To investigate cell formation in hydrocarbon/hydrogen/carbon monoxide-air premixed flames, the outward propagation and cellular instabilities were experimentally studied in a constant pressure combustion chamber at room temperature and elevated pressures. Unstretched laminar burning velocities and Markstein lengths of the mixtures were obtained by analyzing high-speed schlieren images. In this study, hydrodynamic and diffusional- thermal instabilities were evaluated to examine their effects on flame instabilities. The experimentally-measured unstretched laminar burning velocities were compared to numerical predictions using the PREMIX code. Effective Lewis numbers of premixed flames with methane addition decreased for all of the cases; meanwhile, effective Lewis numbers with propane addition increased for lean and stoichiometric conditions and increased for rich and stoichiometric cases for hydrogen-enriched flames. With the addition of propane, the propensity for cell formation significantly was diminished, whereas cellular instabilities for hydrogen-enriched flames were promoted. However, similar behavior of cellularity was obtained with the addition of methane to the reactant mixtures.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1450-1454
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• 2008

In the conventional biology, the most of cell studies was carried out by culturing cells in the Petri dish and by investigating cellular behavior under the diverse bio-molecule (cell signalling materials, drugs or etc.) conditions. However, in vivo environments, diverse stimulations including chemical, mechanical and topological environments involved in the proliferation, differentiation and migration of cells and it is almost impossible to provide these conditions with traditional method. We have developed the methods to provide the well defined chemical and mechanical stimulations using microfluidic devices and applied these approaches to the study of environmental effect on cells. In this paper, we will introduce our microfluidic chips to provide microenvironment and its applications using several cells.

• 한국화재소방학회논문지
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• 제3권2호
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• pp.11-19
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• 1989

In this study, the independent variables are the floor plan configulation. The dependent variables are the occupant's egress behavior, especially spatial movement pattern, and life - safety performance of building. Fire events were simulated on single story of office building. Simulation run for allowable secaping thime(180 seconds) arbitrarily selected, and involved 48 occupants. The major findings Pre as follows. 1) Computer simulation model suggested in this study can be used as the Preoccupancy evaluation method of the life-safety performance for architectural design based on prediction of occupants' egress behavior in the levels of validity and sensitivity, 2) Sucess or failure in occupants' escape is determined by decreasing walking speed caused by jamming at exits or over crowded corridor, and increasing route length caused by running about in confusion at each subdivision and corridor. 3) In floor plan configuration which safe areas located at the extreme ends of the corridor, cellular floor planning have to be avoided preventing jamming and running about in confusion at overcrowded corridor.

• Geomechanics and Engineering
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• 제24권6호
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• pp.589-597
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• 2021

The present study evaluates geocell reinforced slope behavior. A three dimensional analysis is carried out to simulate soil and geocell elastoplastic behavior using the finite difference software FLAC3D. In order to investigate the geocell reinforcement effect, the geocell aperture size, thickness, geocell placement condition and soil compaction had been considered as variable parameters. Moreover, a comparison is evaluated between geocell reinforcing system and conventional planar reinforcement. The obtained results showed that the pocket size, thickness and soil compaction have considerable influence on the geocell reinforcement slope performance. Moreover, it was found that the critical sliding surface was bounded by the first geocell reinforcement and the slope stability increases, by increasing the vertical space between geocell layers. In addition, the comparison between geocell and geogrid reinforcement indicates the efficiency of using cellular honeycomb geosynthetic reinforcement.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.890-893
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• 2002

This study is focused to predict the behavior of Al foam with closed-cell structure during the 3 point bending test and the upsetting test according to aspect ratio. We calculated characters of aluminum foams with closed-cell structure and took the simulation. The effects on the aspect ratio of the cell was investigated parametrically. The analysis was carried out on two models, First, the bending test in elasticity of the rectangular beam, and Second, the upsetting test in plasticity of the circular cylinder. In the analysis, the deformation of the beam and the cylinder was influenced by the aspect ratio of the cell. Further, We assumed that the geometry of feared aluminum cell change the stress and strain in the test.

• 한국멀티미디어학회논문지
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• 제4권4호
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• pp.356-362
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• 2001

본 논문에서는 선형 TPMACA C의 0-tree에서 0이 아닌 상태를 여원벡터로 갖는 CA C'를 분석하여 C의 모든 상태가 C'의 어느 곳에 있는지를 밝혔다. 또한 C의 상태전이 그래프에서 한 경로만 알면 나머지 상태를 모두 알 수 있음을 밝혔다.

• Fibers and Polymers
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• 제2권2호
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• pp.51-57
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• 2001

Tissue engineering is one exciting approach to treat patients who need a new organ or tissue. A critical element in this approach is the polymer scaffold, as it provides a space for new tissue formation and mimics many roles of natural extra-cellular matrices. In this review, we describe several design parameters of polymer matrices that can significantly affect cellular behavior, as well as various polymers which are frequently used to date or potentially useful in many tissue engineering applications. Interactions between cells and polymer scaffolds, including specific receptor-ligand interactions, physical and degradation feature of the scaffolds, and delivery of soluble factors, should be considered in the design and tailoring of appropriate polymer matrices to be used in tissue engineering applications, as these interactions control the function and structure of engineered tissues.