• 한국항공우주학회지
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• 제35권10호
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• pp.905-911
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• 2007

이 논문에서는 기하학적 및 재료적 비선형 유한요소해석을 통하여 멤브레인의 접힘 거동을 연구하였다. 얇은 멤브레인의 단면에 대해 평면변형률을 가정하여 2차원 요소로 모델링 하였다. 접힘 과정은 먼저 멤브레인 메쉬를 접은 후, 두 개의 강체 접촉면을 사용하여 지정된 접힘 간극까지 압축한 다음, 강체 접촉면을 풀어 접힘 형상을 얻는 순서로 모사하였다. 다양한 접힘 간극에 대해 해석을 수행하여 접힘 강도가 초기 전개각에 미치는 영향을 중심으로 결과를 고찰하였다. 또한 실제 시편에 대하여 실험을 수행하여 그 결과를 해석결과와 비교하였다.

• 로봇학회논문지
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• 제8권3호
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• pp.150-155
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• 2013

Vibrotactile actuators for small consumer electronic products, such as mobile devices, have been widely used for conveying haptic sensation to users. One of the most important things in vibrotactile actuators is to be developed in the form of thin actuator which can be easily embedded into mobile devices and to provide vibrotactile signals with wide frequency band to users. Thus, this paper proposes a thin film type haptic actuator with an aim to convey vibrotactile information with high frequency bandwidth to users in mobile devices. To this end, a vibrotactile actuator which creates haptic sensation is designed and constructed based on cellulose acetate material. A cellulose acetate material charged with an electric potential can generate vibration under the AC voltage input. It is found that the motion of the actuator can have concave or convex shape by controlling a polarity of both charged membranes and the actuator performance can be modulated by increasing level of biased electric potential. The experiment clearly shows that the proposed actuator creates enough output force to stimulate human skin with a large frequency bandwidth and to simulate various vibrotactile sensations to users.

• Transactions on Electrical and Electronic Materials
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• 제6권1호
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• pp.18-21
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• 2005

Monolayers of lipids on a water surface have attracted much interest as models of biological membranes, but also as precursors of multilayer systems promising many technical applications. Until now, many methodologies have been developed in order to gain a better understanding of the relationship between the structure and function of the monolayers. Maxwell displacement current (MDC) measurement has been employed to study the dielectric property of Langmuirfilms. MDC flowing across monolayers is analyzed using a rod-like molecular model. A linear relationship between the monolayer compression speed a and the molecular area Am. Compression speed a was about 30, 40, and 50 mm/min. Langmuir-Blodgett(LB) layers of Arachidic acid deposited by LB method were deposited onto slide glass as Y-type film. The structure of manufactured device is Aul Arachidic acid! AI, the number of accumulated layers are $9{\sim}21$. Also, we then examined of the Metal-Insulator-Metal(MIM) device by means of I-V. The I-V characteristics of the device are measured from -3 to+3 V. The insulation property of a thin film is better as the distance between electrodes is larger.

• 센서학회지
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• 제18권4호
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• pp.311-315
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• 2009

This paper describes the characteristics of a poly 3C-SiC micro heater which was fabricated on AlN(0.1 $\mu$m)/3C-SiC(1.0 $\mu$m) suspended membranes by surface micro-machining technology. The 3C-SiC and AlN thin films which have wide energy band gap and very low lattice mismatch were used sensors for high temperature and voltage environments. The 3C-SiC thin film was used as micro heaters and temperature sensor materials simultaneously. The implemented 3CSiC RTD(resistance of temperature detector) and the power consumption of micro heaters were measured and calculated. The TCR(thermal coefficient of the resistance) of 3C-SiC RTD is about -5200 ppm/$^{\circ}C$ within a temperature range from 25 $^{\circ}C$ to 50 $^{\circ}C$ and -1040 ppm/$^{\circ}C$ at 500 $^{\circ}C$. The micro heater generates the heat about 500 $^{\circ}C$ at 10.3 mW. Moreover, durability of 3C-SiC micro heaters in high voltages is better than Pt micro heaters. A thermal distribution measured and simulated by IR thermovision and COMSOL is uniform on the membrane surface.

• 한국항공우주학회지
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• 제39권11호
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• pp.1005-1012
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• 2011

본 연구에서는 기하학적 비선형 후좌굴해석 및 전역-국지해석을 통하여 얇은 막재에서 주름이 파괴거동에 미치는 영향을 연구하였다. 해석에서 양단노치 및 일단노치를 가지는 사각형 인장시험 시편형상을 고려하였으며 주름이 발생한 경우와 억제된 경우에 대해 각각 해석을 수행하여 그 결과를 비교하였다. 해석결과의 분석을 통하여 주름의 발달에 따라 J-적분값의 변화에 미치는 영향을 조사하였고, 컷 길이에 따른 영향 및 시편형상의 길이 효과에 대해 체계적으로 연구하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 영호남 합동 학술대회 및 춘계학술대회 논문집 센서 박막 기술교육
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• pp.20-22
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• 2006

Monolayers of lipids on a water surface have attracted much interest as models of biological membranes, but also as precursors of multilayer systems promising many technical applications. Until now, many methodologies have been developed in order to gain a better understanding of the relationship between the structure and function of the monolayers. Maxwell displacement current (MDC) measurement has been employed to study the dielectric property of Langmuir-films. MDC flowing across monolayers is analyzed using a rod-like molecular model. A linear relationship between the monolayer compression speed and the molecular area Am. Compression speed was about 30, 40, 50mm/min. Langmuir-Blodgett(LB)layers of Arachidic acid deposited by LB method were deposited onto slide glass as Y-type film. The structure of manufactured device is Au/Arachidic acid/Al, the number of accumulated layers are 9~21. Also, we then examined of the Metal-Insulator-Metal(MIM) device by means of I-V. The I-V characteristics of the device are measured from -3 to +3[V]. The insulation property of a thin film is better as the distance between electrodes is larger.

• Biomaterials and Biomechanics in Bioengineering
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• 제2권2호
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• pp.71-84
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• 2015

A low-profile flow sensor has been designed, fabricated, and characterized to demonstrate the feasibility for monitoring hemodynamics in cerebral aneurysm. The prototype device is composed of three micro-membranes ($500-{\mu}m$-thick polyurethane film with $6-{\mu}m$-thick layers of nitinol above and below). A novel super-hydrophilic surface treatment offers excellent hemocompatibility for the thin nitinol electrode. A computational study of the deformable mechanics optimizes the design of the flow sensor and the analysis of computational fluid dynamics estimates the flow and pressure profiles within the simulated aneurysm sac. Experimental studies demonstrate the feasibility of the device to monitor intra-aneurysmal hemodynamics in a blood vessel. The mechanical compression test shows the linear relationship between the applied force and the measured capacitance change. Analytical calculation of the resonant frequency shift due to the compression force agrees well with the experimental results. The results have the potential to address important unmet needs in wireless monitoring of intra-aneurysm hemodynamic quiescence.

• Structural Engineering and Mechanics
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• 제77권5호
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• pp.691-703
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• 2021

Reinforced concrete (RC) beams can be subjected to a complex combination of shear forces (V), torsional moments (T), flexural moments (M) and axial loads (N). This paper proposes a unified approach for the analysis of these elements. An existing model for the analysis of orthogonally reinforced concrete membrane elements subjected to in-plane shear and normal stresses is generalized to apply to the case of beams subjected to the complex loading. The combination of V and T can be critical. Torsion is modelled using the hollow-tube analogy. A direct equation for the calculation of the thickness of the equivalent hollow tube is proposed, and the shear stresses caused by V and T are combined using a simple approach. The development and the evaluation of the model are described. The calculations of the model are compared to experimental data from 350 beams subjected to various combinations of stress-resultants and to the calculations of the ACI and the CSA codes. The proposed model provides the most favorable results. It is also shown that it can accurately model the interaction between V and T. The proposed model provides a unified treatment of shear in beams subjected to complex stress-resultants and in thin membrane elements subjected to in-plane stresses.

• 폴리머
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• 제36권6호
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• pp.810-815
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• 2012

본 연구에서는 폴리아미드 역삼투 복합막 표면에 양이온교환 고분자인 poly(styrene sulfonic acid)(PSSA)를 코팅한 후 모델 오염물질인 bovine serum albumin(BSA), humic acid(HA), sodium alginate(SA)에 대하여 파울링 개선 효과가 있는지를 알아보고자 하였다. PSSA가 코팅된 폴리아미드 복합막의 표면에 대한 접촉각을 확인한 결과 $78^{\circ}$에서 $58^{\circ}$로 낮아져 표면이 친수화된 것을 확인하였다. 모델 오염물질로서 BSA, HA, SA 등이 100 ppm 용해된 공급원액을 2, 4, 8 atm 조건에서 PSSA 코팅된 막과 코팅되지 않은 막에 대하여 파울링 실험을 수행한 결과 압력이 증가함에 모든 오염물질에 대해서 파울링은 심화되었다. 파울링은 BSA>SA>HA의 순으로 일어났으며 PSSA가 코팅된 막에 대해 파울링 개선효과는 HA>SA>BSA의 순으로 나타났다. 이는 막표면의 PSSA가 지니는 설폰산과 오염물질의 작용기간의 상호작용으로 인한 결과이며, 이는 SEM으로 관찰한 사진과도 같은 경향을 보여주었다. 결론적으로 PSSA가 코팅된 역삼투막은 파울링 개선효과가 있었으며 HA의 경우에서 가장 두드러졌다.

• 멤브레인
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• 제22권4호
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• pp.272-279
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• 2012

본 연구에서는 폴리아마이드 역삼투 복합막 표면에 중성 친수성 고분자인 poly (vinyl alcohol) (PVA)를 코팅한 후 모델 오염물질인 bovine serum albumin (BSA), humic acid (HA), sodium alginate (SA)에 대하여 파울링 개선 효과가 있는지를 알아보고자 하였다. 고분자의 파울링 유도를 위해 모델 오염물질인 BSA, HA, SA 등이 100 ppm으로 용해된 공급원액을 2, 4, 8 atm 조건에서 PVA 코팅된 막과 코팅되지 않은 막에 대하여 파울링 실험을 수행한 결과. 압력이 증가함에 모든 오염물질에 대해서 파울링은 심화되었다. 파울링 심화 현상은 BSA > HA > SA의 순으로 일어났으며, PVA가 코팅된 막에 대해 파울링 개선효과는 HA > BSA > SA의 순으로 나타났다. 전자현미경 사진 결과에서도 같은 경향을 보여주고 있다. 결국, PVA가 코팅된 역삼투막은 어느 경우에서나 파울링 개선효과는 뚜렷하게 있었으며 HA의 경우에서 가장 두드러졌다.