• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.54-55
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• 2006

Polymeric micelles, supramolecular assemblies of block copolymers, are useful nanocarriers for the systemic delivery of drugs and genes. Recently, novel polymeric micelles with various functions such as the targetability and stimuli-sensitivity have been emerged as promising carriers that enhance the efficacy of drugs and genes with minimal side effects. This presentation focuses our recent approach to the preparation of functional block copolymers that are useful for constructing smart micellar delivery systems in advanced therapeutics, including chemo-gene therapy. Particular emphasis is placed on the characteristic behaviors of intracellular environment-sensitive micelles that selectively exert drug activity and gene expression in live cells.

• Transactions on Electrical and Electronic Materials
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• 제11권5호
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• pp.197-201
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• 2010

As the world population increases and technology advances, the energy consumption and need for more energy increase. Communities and governments regularly address these needs and set policies for future energy generation and uses. This paper reviews current energy policies of the USA and the current trends in research and development efforts, for sustainable and renewable energy sources. Furthermore, the recent topic of IEEE's Smart Grid initiatives is discussed, and its role in the dielectrics and electrical insulation research is presented.

• Advances in aircraft and spacecraft science
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• 제9권6호
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• pp.553-569
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• 2022

In this article, we propose a criterion for ensuring the asymptotic stability of large multiple delays, based on the direct Lyapunov method. Based on this criterion and distributed control scheme, the controllers are synthesized by the PDC to stabilize these large-scale systems with multiple delays. And we focus on the results which shows the high effective by the proposed theory utilized for damage propagation for aircraft structural analysis of composite materials. Finally, the numerical simulations confirmed the effectiveness of the method.

• 디지털융복합연구
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• 제10권8호
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• pp.15-20
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• 2012

스마트그리드의 성공적 구축을 위해 스마트그리드 시범사업이 추진 및 확대되고 있다. 이 시범사업을 보다 바람직한 방향으로 발전시키기 위해서는 타당하고 객관적인 성과 평가가 이루어져야 한다. 본 연구에서는 국내 현실에 맞는 스마트그리드 시범사업 성과 평가기준을 제시하고, 시범사업 형태에 따라 지속적으로 평가기준을 발전시켜 나갈 수 있는 기반을 마련하고자 한다. 이에 주요 연구문헌 검토와 전문가회의를 통해 스마트그리드 시범사업 성과 평가기준의 초안을 마련하였다. 이렇게 마련된 평가기준 초안은 전문가 델파이 조사를 통해 국내 현실에서의 타당성을 검증하였다. 총 2차례의 델파이조사를 거쳤으며, 조사 결과 6개 평가항목에 18개 평가기준을 도출하였다.

• Smart Structures and Systems
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• 제17권1호
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• pp.135-147
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• 2016

This paper describes a smart structural system, which uses smart materials for real-time monitoring and active control of bolted-joints in steel structures. The goal of this research is to reduce the possibility of failure and the cost of maintenance of steel structures such as bridges, electricity pylons, steel lattice towers and so on. The concept of the smart structural system combines impedance based health monitoring techniques with a shape memory alloy (SMA) washer to restore the tension of the loosened bolt. The impedance-based structural health monitoring (SHM) techniques were used to detect loosened bolts in bolted-joints. By comparing electrical impedance signatures measured from a potentially damage structure with baseline data obtained from the pristine structure, the bolt loosening damage could be detected. An outlier analysis, using generalized extreme value (GEV) distribution, providing optimal decision boundaries, has been carried out for more systematic damage detection. Once the loosening damage was detected in the bolted joint, the external heater, which was bonded to the SMA washer, actuated the washer. Then, the heated SMA washer expanded axially and adjusted the bolt tension to restore the lost torque. Additionally, temperature variation due to the heater was compensated by applying the effective frequency shift (EFS) algorithm to improve the performance of the diagnostic results. An experimental study was conducted by integrating the piezoelectric material based structural health monitoring and the SMA-based active control function on a bolted joint, after which the performance of the smart 'self-monitoring and self-healing bolted joint system' was demonstrated.

• 한국전기전자재료학회논문지
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• 제33권4호
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• pp.271-275
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• 2020

Smart windows are used as windows and doors to determine the cooling and heating efficiency of a building. They have characteristics that can increase the energy efficiency of a building, which leads to energy savings. In addition, smart windows can control the amount of light transmitted from the external environment of a building to the interior of a building according to the needs of the user. In this study, a 297×210 ㎟ liquid crystal cell capable of controlling light transmittance was fabricated using a liquid crystal device as an optical shutter. The effect of driving voltage on the transmittance and the effect of the thermal environment on the driving stability were analyzed. We confirmed the applicability of using smart windows as exterior building materials.

• Smart Structures and Systems
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• 제10권1호
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• pp.67-87
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• 2012

A dragonfly inspired flapping wing is investigated in this paper. The flapping wing is actuated from the root by a PZT-5H and PZN-7%PT single crystal unimorph in the piezofan configuration. The non-linear governing equations of motion of the smart flapping wing are obtained using the Hamilton's principle. These equations are then discretized using the Galerkin method and solved using the method of multiple scales. Dynamic characteristics of smart flapping wings having the same size as the actual wings of three different dragonfly species Aeshna Multicolor, Anax Parthenope Julius and Sympetrum Frequens are analyzed using numerical simulations. An unsteady aerodynamic model is used to obtain the aerodynamic forces. Finally, a comparative study of performances of three piezoelectrically actuated flapping wings is performed. The numerical results in this paper show that use of PZN-7%PT single crystal piezoceramic can lead to considerable amount of wing weight reduction and increase of lift and thrust force compared to PZT-5H material. It is also shown that dragonfly inspired smart flapping wings actuated by single crystal piezoceramic are a viable contender for insect scale flapping wing micro air vehicles.

• Smart Structures and Systems
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• 제13권2호
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• pp.319-341
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• 2014

A family of smart tuned mass dampers (STMDs) with variable frequency and damping properties is analyzed under harmonic excitations and ground motions. Two types of STMDs are studied: one is realized by a semi-active independently variable stiffness (SAIVS) device and the other is realized by a pendulum with an adjustable length. Based on the feedback signal, the angle of the SAIVS device or the length of the pendulum is adjusted by using a servomotor such that the frequency of the STMD matches the dominant excitation frequency in real-time. Closed-form solutions are derived for the two types of STMDs under harmonic excitations and ground motions. Results indicate that a small damping ratio (zero damping is the best theoretically) and an appropriate mass ratio can produce significant reduction when compared to the case with no tuned mass damper. Experiments are conducted to verify the theoretical result of the smart pendulum TMD (SPTMD). Frequency tuning of the SPTMD is implemented through tracking and analyzing the signal of the excitation using a short time Fourier transformation (STFT) based control algorithm. It is found that the theoretical model can predict the structural responses well. Both the SAIVS STMD and the SPTMD can significantly attenuate the structural responses and outperform the conventional passive TMDs.

• 항공우주시스템공학회지
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• 제9권3호
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• pp.1-7
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• 2015

In this study, the design of compound smart materials hydraulic pump that can be applied to a small-medium size UAV having a limited space envelope and weight has been conducted. Compound Smart Material Pump(CSMP) proposed in this paper is composed of a pressurize pump and a flow pump for supplying the high pressure and fluid displacement to overcome the disadvantages of the piezoelectric actuator which has a small strain. Though this compound smart material pump has been designed as small size and lightweight as possible, it can sequentially supply the sufficient large flow rate and pressure required for the brake operation. For the design of CSMP, about 2,700 kg (6,000 lb) class fixed wing manned aircraft was selected. Based on the established requirements, the design of the CSMP have been done by strength, vibration, and fluid flow analysis.

• 한국전자통신학회논문지
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• 제16권2호
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• pp.363-370
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• 2021

외곽 침입감지 시스템은 물리 보안에 있어서 중요한 비중을 차지하고 있다. 본 연구에서는 외곽 침입감지를 위해 IoT 환경에서 적용할 수 있는 MEMS 센서를 활용한 초소형 스마트 디바이스를 개발하고 그 성능을 평가하였다. 본 연구에서 개발한 스마트 디바이스를 적용한 외곽 침입감지 시스템은 다양한 재질, 형태의 철조망이 도심, 바닷가, 산속 등 다양한 설치환경에 설치되어 외부의 침입과 그 위치를 감지할 수 있을 뿐 아니라, 오경보율과 구축비용 등을 최소화할 수 있는 스마트 센서로 국가 및 민간 주요 시설의 외각 침입 감지 위해 활용될 수 있을 것으로 기대한다.