• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 추계학술대회논문집 II
• /
• pp.1120-1125
• /
• 2001

A new concept of piezoelectric smart panels for noise reduction in wide band frequencies is proposed and their possibility is experimentally investigated. Multi-mode damping is studied by using a newly proposed tuning method. The proposed panels are based on passive shunt damping methods. This method is based on electrical impedance model and maximizing the dissipated energy at the shunt circuit. four PZT are attached on smart panel for improving performance of transmission noise reduction. 0 prove the concept of piezoelectric smart panels, an acoustic measurement experiment was performed. The smart panels exhibit a good noise reduction in middle and high frequency ranges due to the mass effects of absorbing materials or/and the air gap. The use of piezoelectric smart panel renders noise reduction at resonance frequency. Noise reduction at multiple resonance frequencies is experimentally investigaed.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2005년도 추계학술대회논문집
• /
• pp.541-544
• /
• 2005

In this paper, admittance is introduced to represent electro-mechanical characteristics of piezoelectric structures and to predict the performance of piezoelectric shunt system. Finite element method is used to obtain numerical admittance. In order to illuminate the effect of noise reduction in the shunt system, two experimental setups were constructed. One is for matching the resonant shunt damping. The other is a standard test setup according to SAE J1400 used to measure the transmission loss for the smart panel with shunt circuit. Shunt performance and noise reduction of smart panel are realized by these two experiments.

• 아태비즈니스연구
• /
• 제9권3호
• /
• pp.37-50
• /
• 2018

This paper examines the relationship between diversification and financial performance of community credit unions in Korea from 2011 to 2017. To do so, I employ fixed-effects panel analyses using credit union level panel data collected from the National Credit Union Federation of Korea. This study finds evidence that business diversification is likely to lower the ratio of troubled loans, which means improving asset quality of credit unions. However, the relationship between diversification and asset quality is not linear but nonlinear, which means over-diversification would have negative effects on asset quality. Next, diversification tends to increase profitability. Specifically, although diversification results in a rise in expenditures, an increase in profits made by diversification outweighs the rise in expenditures, which contributes to profitability. Put together, diversification would be a good business strategy to improve both profitability and asset quality. Given a result that fast loan growth deteriorates asset quality, credit unions' managers might adopt the diversification strategy to enhance asset quality, and not to pursue their own objectives motivated by moral hazards.

• 한국농공학회논문집
• /
• 제57권2호
• /
• pp.57-66
• /
• 2015

The purpose of this study was to improved the durability of a improved movable weir by replacing the improved movable weir's metal gate with a hybrid steel/glass fiber reinforced polymer composites panel gate. Because the metal gate of a improved movable weir is always in contact with water, its service life is shortened by corrosion. This study made four type of hybrid steel/glass fiber reinforced polymer composites panel gate with different steel gate surface deformation (control, sand blast, scratch and hole), flexural. Fracture properties tests were performed depending on the steel gate surface deformation. According to the test results, the flexural behavior, flexural strength and fracture properties of hybrid steel/glass fiber reinforced polymer composites panel gate was affected by the steel panel gate surface deformation. Also, the sand blast type hybrid steel/glass fiber reinforced polymer composites panel gate shows vastly superior flexural and fracture performance compared to other types.

• Steel and Composite Structures
• /
• 제18권5호
• /
• pp.1177-1195
• /
• 2015

Six specimens are tested to investigate the cyclic behavior of beam-to-column abnormal joints in steel moment-resisting frames, which are designed according to the principle of strong-member and weak-panel zone. Key parameters include the axial compression ratio of column and the section depth ratio of beams. Experimental results indicate that four types of failure patterns occurred during the loading process. The $P-{\Delta}$ hysteretic loops are stable and plentiful, but have different changing tendency at the positive and negative direction in the later of loading process due to mechanical behaviors of specimens. The ultimate strength tends to increase with the decrease of the section depth ratio of beams, but it is not apparent relationship to the axial compression ratio of column, which is less than 0.5. The top panel zone has good deformation capacity and the shear rotation can reach to 0.04 rad. The top panel zone and the bottom panel zone don't work as a whole. Based on the experimental results, the equation for shear strength of the abnormal joint panel zone is established by considering the restriction of the bottom panel zone to the top panel zone, which is suitable for the abnormal joint of H-shaped or box column and beams with different depths.

• 한국정밀공학회지
• /
• 제25권6호
• /
• pp.71-79
• /
• 2008

In the manufacture of flat panel display devices, there is a strong demand for contactless glass panel handling devices that can manipulate a glass panel without contaminating or damaging it. To fulfill this requirement, an electrostatic suspension device far glass panels where the glass panel is supported by electrostatic forces without any mechanical contact is proposed. To implement the system with low cost and compactness, switched-voltage control scheme that is based on the relay feedback control is utilized. Relay feedback control method deploys only a single high-voltage power supply that can deliver a DC voltage of positive and/or negative polarity and thus high voltage amplifiers that are costly and bulky are not needed any more. It is shown that despite the inherent limit cycle property of the relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping originating from the electrodes and levitated object. Using this scheme, a $100{\times}100mm^2$ glass panel was levitated stably with airgap variation decreasing down to $1\;{\mu}m$ at an airgap of $100\;{\mu}m$.

• 한국태양에너지학회 논문집
• /
• 제30권2호
• /
• pp.10-15
• /
• 2010

The experimental study was conducted to optimize the system dissipating properly heat from the in-situ solar panel installed on the roof. For this purpose, six 12-Watt panels, which were consisted of the different design conditions such as containing phase change material(PCM), changing the array of the aluminum fin and honeycomb at the back of the panel, were tested. PCM, which had $44^{\circ}C$ melting point, was chosen in this study. In order to enhance absorbing and expelling heatin PCM, profiled aluminum fin was placed either inward oroutward from the panel. Furthermore, Aluminum honeycomb is imbedded in the back container to find if it would improve the thermal conductivity of PCM. During the experiment, there were ranged to $26^{\circ}C\sim32^{\circ}C$ for outdoor temperature and $700W/m^2\sim1000W/m^2$ for irradiance. As a result, the solar panel, combined with honeycomb and outward fins with PCM instead of placing the fins inward, is showing the best performance in terms of controling panel temperature and its efficiency.

• 대한건축학회논문집:구조계
• /
• 제33권12호
• /
• pp.71-80
• /
• 2017

The purpose of this study is to applied reinforcement method at the joint part of the sandwich panel. Becasue the joint part of the sandwich panel has a disadvantage that flame spreads fast inside steel plates in the event of fire, leading to a big fire rapidly. In this study, the combustion performance was measured through KS F ISO 13784-1 "Reaction-to-fire tests for sandwich panel building systems" according to the application of reinforcement method to prevent flame from being brought into the internal joint of the sandwich panel. For the reinforcement inside the panel, the tape produced using expanded graphite-based heat-expandable glass fiber was attached. As a result, it was confirmed that the prevention of flame from being brought into the internal joint could delay the flash over time and the collapse of the test specimen.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2022년도 봄 학술논문 발표대회
• /
• pp.176-177
• /
• 2022

In this study, surface performance evaluation was conducted according to the fiber and surface finishing technique of the exterior material using Ultra High Performance Concrete(UHPC), whitch is spotlighted as a highly durable exterior material. As a result of outdoor exposure, the initial performance of the UHPC Panel using organic fibers was maintained without being affected by the surface finishing technique. In the specimen using steel fiber, the surface performance was maintained when the water repellent treatment was performed in the plain specimen, but fiber corrosion occurred in the specimen to which the surface finishing technique was applied.

• 산업융합연구
• /
• 제22권2호
• /
• pp.1-12
• /
• 2024

본 연구는 은행 성과와 관련하여 어떠한 의사결정이 영향을 미치는지 연구하고 있다. 2013년부터 2022년까지 미국에 소재한 은행의 재무제표상 자료를 이용하여 패널회귀분석을 진행하였으며, 재무적 의사결정, 경영 의사결정으로 나누어 위계적 패널회귀분석을 통해 설명변수의 효과를 살펴본다. 또한, 채권자와 주주 관점(이하 전체)과 주주만의 관점으로 성과를 나누어 분석함으로써, 각 관점의 성과를 제고시키기 위해서는 어떠한 요소를 어떻게 활용해야 하는지를 제시하고 있다. 유동성과 안정성만으로 패널회귀분석을 수행했을 시 전체 성과 관점에서는 예금 의존도와 이자보상비율이, 주주 성과 관점에서는 부채비율도 통계적으로 유의한 영향을 미쳤다. 비기술적 요소까지 더할 시엔 전체 성과 관점에서는 비기술적 요소 중 인건비 비중만이 통계적으로 유의하게 도출되었고 주주 성과 관점에서는 비기술적 요소가 통계적으로 유의하게 도출되진 않았지만, 현금비율은 통계적으로 유의한 영향을 주는 것으로 도출되었다. 마지막으로 기술적 혁신요소까지 더할 시에는 전체 성과 관점에서는 무형자산 비중이 통계적으로 유의한 것으로 도출되지 않았지만, 주주 성과 관점에서는 유의하게 도출되었다. 이해관계자의 성과 관점에 따라 미칠 수 있는 요인이 차이가 있다는 점, 그리고 다양한 의사결정 요소가 은행의 성과에 영향을 미칠 수 있다는 점이 본 연구의 의의 및 시사점이다.