• International Journal of Automotive Technology
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• 제6권6호
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• pp.607-613
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• 2005

In this study, a simplified approach to modeling the dynamic characteristics of passive constrained layer damping treatments in finite element models is presented. The basic concept is to represent multi-layered composite structures using an equivalent single layer. The equivalent properties are obtained by using the RKU (Ross, Kerwin and Ungar) equations. Comparisons are given between results obtained by the dynamic analysis of the simple models implemented in MSC/NASTRAN and by test measurements. Surface damping treatments are applied to automotive panels as well as simple structures. Using the proposed equivalent modeling technique, higher computational efficiency for the damped composite structures has been obtained.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.319-322
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• 2009

This paper investigated environmental effects for passive, air-breathing, and vapor-feeding direct methanol fuel cells. In these experiments, experimental parameters are temperature($30^{\circ}C$, $40^{\circ}C$ and relative humidity(25%, 50%, 75%). From these experimental results, the water contents play a key role in terms of optimal ionic conductivity at the cathode catalyst layer. In case of pure methanol feeding, the performance is inversely proportional to the relative humidity. The water generation resulting from methanol crossover maintains ionic conductivity at the cathode. On the contrary, diluted methanol solution (50wt.%) lowers methanol crossover to the cathode. In order to increase ionic conductivity, the relatively high humidity is required to the cathode catalyst layer for the water generation. The relative humidity scales with the performance.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.187-188
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• 2003

In order to control the transonic flow field with shock wave, a condensing flow was produced by an expansion of moist air on a circular bump model and shock waves were occurred in the supersonic parts of the fields. Furthermore, the additional passive technique of shock - boundary layer interaction using the porous wall with a cavity underneath was adopted in this flow field. The effects of these methods on the shock wave characteristics were investigated numerically. The result showed that the flow fields might be effectively controlled by the suitable combination between non-equilibrium condensation and the position of porous wall.

• 한국소음진동공학회논문집
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• 제11권4호
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• pp.37-42
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• 2001

Active vibration control of laminated composite plates has been carried out to design structure with maximum possible damping capacity, using piezoceramic sensor/actuators and passive constrained-layer damping treatment. The equations of motion are derived for symmetrical, multi-layer laminated plates. The damping ratio(ζ) and modal damping(2ζ$\omega$) of the first bending and torsional modes are calculated by means of iterative complex eigensolution method for both passive and active vibration control. This paper addresses a design strategy of laminated composite plate under structural vibrations.

• 한국정밀공학회지
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• 제18권10호
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• pp.148-153
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• 2001

Active control of flexural vibrations of smart laminated composite beams has been carried out using piezoceramic sensor/actuator and viscoelastic material. The beams with passive constrained layer damping hale been analyzed by formulating the equations of motion through the use of extended Hamilton's principle. The dynamic characteristics such as damping ratio and modal damping of the beam are calculated for various fiber orientations by means of iterative complex eigensolution method. This paper addresses a design strategy of laminated composite under flexural vibrations to design structure with maximum possible damping capacity.

• 한국소음진동공학회논문집
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• 제12권12호
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• pp.950-955
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• 2002

The coupled finite/boundary element method is used in numerical analysis for acoustic radiation from the vibration of rectangular composite plate which is simply supported. This analysis is validated using the Wallace equation for an isotropic plate. Active control of sound fields has been tarried out using 3 pairs of piezoelectric sensor/actuator and a pair of viscoelastic material by Passive constrained layer damping treatment. The results show that the optimal placement of piezoelectric sensor/actuator and VE patch is required to control the sound fields from a vibrating composite plate.

• Archives of Metallurgy and Materials
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• 제64권2호
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• pp.487-490
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• 2019

In this study, the corrosion properties of Ti-6Mo-6V-5Cr-3Sn-2.5Zr alloy were investigated as a function of the cold rolling ratio and annealing temperature. The annealing treatment was carried out at temperature of 680℃, 730℃, and 780℃. The highest corrosion potential observed in the specimen with a 10% rolling ratio was 179 mV, which was more positive than that of the non-rolled specimen (-0.214 V_ssc). The lowest corrosion current density (1.30×10^-8 A/cm²) was observed in the non-rolled specimen which suggested that the integrity of its passive oxide layer was superior to that of the cold-rolled specimens. Time-dependent EIS evaluation revealed that the consistency of the passive oxide layer was highly affected by the subjected rolling ratio over time.

• 한국해양학회지:바다
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• 제24권2호
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• pp.249-265
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• 2019

수동형채집기(passive sampler)는 해수나 퇴적물 내 공극수에서의 자유용존상 농도 (freely dissolved and bioavailable concentration, $C_{free}$)를 쉽고 보다 정확히 예측할 수 있는 유망한 방법 중 하나이다. 유럽이나 미국에서는 보다 정확한 위해도 평가를 위해 해양환경 모니터링에 수동형채집기를 적극적으로 사용하는 추세이지만, 현장 적용 시 노출시간이 길어짐에 따라 수동형채집기의 생물부착으로 인한 문제점으로 국내에서의 활용도는 매우 낮다. 따라서 본 연구에서는 난분해성 유기오염물질을 대상으로 하는 수동형채집기의 원리 및 기본적인 특징을 파악하고, 수동형채집기의 현장 적용을 위한 다양한 개선 사례를 조사함으로써 국내에서의 수동형채집기의 활용도를 높이기 위한 방안을 제시하였다.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2000년도 춘계총회 및 학술발표회
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• pp.26-26
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• 2000

• 한국통신학회:학술대회논문집
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• 한국통신학회 2004년도 하계종합학술발표회논문초록집
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• pp.115-115
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• 2004