• 한국지반환경공학회 논문집
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• 제10권4호
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• pp.59-63
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• 2009

본 연구는 지반개량공법에 사용되는 동전기 공법에서 나노섬유를 전극재로 사용하여 지반개량효과 및 나노섬유에 대한 전극재로서의 대체가능성을 확인하였다. 이를 위해 Electrokinetic cell을 제작하여 나노섬유를 PBD에 삽입 후 교반된 Kaolin clay에 전기삼투를 적용한 후 실험전후의 침하량, 함수비, 압밀배수량, 전단강도에 대한 지반개량효과를 비교 분석하였다. 또한 전기삼투실험은 전극거리와 전압경사를 변화시키면서 실험을 수행하였으며, 그 결과로 전압경사증가 및 전극거리가 감소할수록 침하량, 전단강도, 압밀배수량은 증가하였고 함수비는 감소하는 것으로 나타났다. 이는 지반개량을 위한 동전기 적용시 사용되는 전극재의 소재로 나노섬유가 충분한 가능성이 있는 것으로 판단된다.

• 한국식품과학회지
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• 제19권2호
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• pp.171-175
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• 1987

삶은 국수의 식미 평가를 위한 객관적 측정 방법으로 레오메타에 특수하게 고안한 test cell을 사용하는 층밀림 압출 시험법을 개발하였다. 층밀립 압출 시험에서 얻어지는 힘-거리 곡선을 분석하여 최초 압출력, 최고 압출력, 압출일, 경사도 등의 파라메타를 구하였다. 17종류의 호주밀로부터 만든 밀국수(건면)에 대한 실험 결과, 최초 압출력 압출일은 삶은 국수의 기호도를 가장 크게 영향하는 단단하고 무른 성질과 쫄깃쫄깃한 성질의 정도를 나타낼 수 있었다. 한편, 경사도는 삶은 국수의 저장중에 일어나는 조직감 변화를 감지할 수 있었다. 이들 파라메타들은 원료 밀가루의 단백질 함량, 수분흡수력, 발전시간(D.T.), 인장도와 높은 삼관관계를 나타내었으나 비스코그램의 최고 점도와는 상관관계를 나타내지 않았다. 비스코스램의 최고 점도와 층밀림 압출 시험의 최고 압출력을 두 독립변수로 한 다중회귀분석 결과 관능적 조직감 기호도와의 상관계수는 최고 압출력만을 사용한 단순회귀분석상관계수보다 크게 증가하지 않았다.

• 한국정밀공학회지
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• 제28권5호
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• pp.623-631
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• 2011

Metallic sandwich panels based on a truss core structure have been developed for a wide range of potential applications with their lightweight and multi-functionality. Structural performance of sandwich panels can be predicted from the studies on mechanical behavior of a unit cell of truss core structures. Analytical investigations on the unit cell provide approximated guidelines for the design of overall core structures for a specific application in short time. In this study, the effects of geometrical parameters on mechanical behavior of a pyramidal shape of unit cell were investigated with analytical models. The unit cell with truss member angle of 45 degree was considered as reference model and other models were designed to have the same weight and projected area but different truss member angle. All truss members were assumed to be connected with pin joint in analytical models. Under the assumptions, the equivalent strength and stiffness of the unit cell under compressive and shear loads were predicted and compared. And finally, the optimum core member angle to have maximum mechanical property could be calculated and verified with FE analysis results.

• 지질공학
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• 제23권4호
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• pp.511-517
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• 2013

Field Velocity Probe (FVP)는 관입형 전단파 탐사 장비로 다양한 현장의 적용성이 날로 증가하고 있다. 본 연구에서는 FVP의 활용성을 증대시키는 측면으로 FVP를 이용하여 연약지반의 압밀 특성을 평가하는 것이다. 대상지반은 국내 대표 연약지반인 인천 송도 지역이며 실내압밀 실험을 수행하기 위하여 시료를 3 m와 6 m에서 채취 하였다. 채취한 시료는 개량된 압밀 시료기에 안착시켜 유효응력 변화에 따른 전단파 속도 경향성을 분석하였다. 현장의 전단파 속도는 FVP를 이용하였으며 매 심도 20 cm 간격으로 상세한 속도 주상도를 도출하였다. 동일 유효응력 조건에서 도출한 실내 전단파 속도와 현장 전단파 속도를 비교하여 연약지반의 압밀 상태를 평가 하였으며 3 m 구간은 과압밀 그리고 6 m 지역은 압밀 진행중인 상태로 나타났다. 본 연구에서는 FVP가 연약지반의 압밀 평가에도 활용될 수 있음을 보여주며 기존 방법의 대체 방법으로 활용성 될 것으로 판단된다.

• International Journal of Aeronautical and Space Sciences
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• 제18권2호
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• pp.222-235
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• 2017

In this study, finite element modeling was used to predict the material properties of tri-axially braided textile composite. The model was made based on an experimental test specimen which was also used to compare the final results. The full interlacing of tows was geometrically modelled, from which repeating parts that make up the whole braid called unit cells were identified based on the geometric and mechanical property periodicity. In order to simulate the repeating nature of the unit cell, periodic boundary conditions were applied. For validation of the method, a reference model was analyzed for which a very good agreement was obtained. Material property calculation was done by simulating uniaxial and pure shear tests on the unit cell. The comparison of these results with that of experimental test results showed an excellent agreement. Finally, parametric study on the effect of number of plies, stacking type (symmetric/anti-symmetric) and stacking phase shift was conducted.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.269-270
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• 2002

Oxygen is a key substrate in animal cell metabolism and its consumption is thus a parameter of great interest for monitoring and control in animal cell culture bioreactor. The use of a gas-permeable membrane offered the possibility to provide the required quantity of oxygen into the culture. while avoiding problems of foaming or shear damage generally linked to sparging. For determining the optimum DO control strategy of this gas-permeable membrane aeration bioreactor, the oxygen transfer rate coefficient was measured with varying $N_2$ ratio in inlet air. The results showed that an increasing mass flow rate of nitrogen reduced the $K_La$ value. and 5% nitrogen in air did not result in any oxygen limitation.

• Structural Engineering and Mechanics
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• 제4권6호
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• pp.613-630
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• 1996

The homogenization method is used to develop a beam element in space for thermo-mechanical analysis of unidirectional composites. Local stress and temperature field in the microscale are described using the function of homogenization. The global (macroscopic) behaviour of the structure is supposed to be that of a beam. Beam-type kinematical hypotheses (including independent shear rotations) are hence applied and superposed on the microdescription. A macroscopic stiffness matrix for such a beam element is then developed which contains the microscale properties of the single cell of periodicity. The presented model enables us to analyse without too much computational effort complicated composite structures such as e.g. toroidal coils of a fusion reactor. We need only a FE mesh sufficiently fine for a correct description of the local geometry of a single cell and a few of the newly developed elements for the description of the global behaviour. An unsmearing procedure gives the stress and temperature field in the different materials of a single cell.

• Steel and Composite Structures
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• 제27권2호
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• pp.135-147
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• 2018

Quasi-static three-point bending tests on sandwich beams with expanded metal sheets as core were conducted. Relationships between the force and displacement at the mid-span of the sandwich beams were obtained from the experiments. Numerical simulations were carried out using ABAQUS/EXPLCIT and the results were thoroughly compared with the experimental results. A parametric analysis was performed using a Box-Behnken design (BBD) for the design of experiments (DOE) techniques and a finite element modeling. Then, the influence of the core layers number, size of the cell and, thickness of the substrates was investigated. The results showed that the increase in the size of the expanded metal cell in a reasonable range was required to improve the performance of the structure under bending collapse. It was found that core layers number and size of the cell was key factors governing the quasi-static response of the sandwich beams with lattice cores.

• 대한의용생체공학회:의공학회지
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• 제43권2호
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• pp.71-80
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• 2022

The interaction between dual-ligand decorated particle-based delivery system and target cell under shear flow is predicted using probability model developed. We assumed the two kinds of ligand are decorated on the surface of the particle with 10% length difference. Fixed with other biophysical parameters, a study on the particle-cell interaction for the different non-specific interaction parameter is performed. To induce the firm adhesion, short ligand-receptor should be engaged. Also, it is shown that the rational design of ligand-receptor interaction, including receptor number, specific interaction parameter, kinds of ligand-receptor, etc., should be considered.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3150-3155
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• 2007

This paper describes an experimental work to investigate the effect of mesh screen device on the jet structure and acoustic characteristics of over-expanded supersonic jet. The mesh screen device is placed into the supersonic jet stream. In order to perturb mainly the initial jet shear layer, the hole is perforated in the central part of the mesh screen. The diameter of the perforated hole and the location of mesh screen device are varied. A Schlieren optical system is used to visualize the flow fields of supersonic jet without and with the mesh screen device. Pitot pressure measurement is carried out to obtain the pressure distribution in the jet flow. Acoustic measurement also is performed to obtain the OASPL and noise spectra. The results obtained show that the jet structure and the jet noise control effectiveness is strongly dependent upon the diameter of the perforated hole and the location of the mesh screen device in the jet stream. Provided that the mesh screen device is placed at the location to perturb effectively the initial shear layer, the present control method is effective in suppressing the supersonic jet noise.