• 대한전자공학회논문지SD
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• 제43권4호
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• pp.1-7
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• 2006

RF 마그네트론 스퍼터링 방법을 이용하여 $Ar/N_2$ 가스비와 기판 온도 변화에 따른 AlN 박막의 배향성과 표면 거칠기 그리고 압전 특성의 변화를 조사하였다. 특히, $Ar/N_2$=10/10 (sccm), 기판 온도 $400^{\circ}C$ 일 때 가장 우수한 (002) 배향성을 얻을 수 있었다. AFM 을 이용하여 표면 거칠기를 분석한 결과, 기판 온도 $400^{\circ}C$ 인 경우 $Ar/N_2$ 가스비의 변화에 대해서는 $N_2$의 분압비가 증가할수록 표면 거칠기 특성이 좋아지는 것으로 나타났으며 $Ar/N_2$=0/20 (sccm) 일 때 2.1 nm 로 가장 작은 값을 나타내었다. $Ar/N_2$=10/10 (sccm) 인 조건에서 기판 온도 변화에 대한 표면 거칠기 특성은 기판 온도가 상온에서 $300^{\circ}C$ 로 증가함에 따라 향상되는 경향을 보였으며, $300^{\circ}C$ 에서 3.036 nm 로 최소값을 나타낸 후, 기판 온도가 $300^{\circ}C$ 이상으로 상승하면 표면 거칠기는 다시 열악해지는 것을 확인할 수 있었다. Pneumatic probe 방법을 이용하여 압전 특성을 측정한 결과, $Ar/N_2$=10/10 (sccm), 기판 온도 $400^{\circ}C$ 일 때 Piezoelectric constant ($d_{33}$)=6.01 pC/N 이라는 가장 우수한 값을 나타내었으며, 이는 AlN 박막이 가장 좋은 (002) 배향성을 갖는 조건과 일치하는 것이다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.399-400
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• 2009

• 대한기계학회논문집A
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• 제39권9호
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• pp.859-869
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• 2015

횡등방성 압전재료에 기하학적 비대칭인 쐐기균열문제를 해석하였다. 기계적 집중면외하중과 전기적 집중 면내하중이 쐐기표면 점에 작용하고 있고, 반면에 균열면 한점에는 기계적 집중하중만 작용한다. 균열면은 침투형 얇은 슬릿으로 가정하여, 전기변위의 수직성분 및 전위가 균열면을 가로질러 연속으로 두었다. Mellin 변환을 사용하여 문제를 수식화하고, Wiener-Hopf 식을 유도하였다. 이 식을 풀므로써 폐형으로 주어지는 해를 얻었다. 임의 균열길이나 경사각, 쐐기각에 대해서도 적용이 가능한 응력 및 전기변위 강도계수를 구하였다. 장의 강도계수들은 전기적 하중에는 무관하고, 전기변위강도계수는 응력강도계수만의 함수로 표현되었다. 전기장 강도계수는 영으로 계산되었다. 또한 에너지방출률을 얻었다. 이 해는 중첩에 의하여 임의로 분포하는 전기기계하중문제에 대한 해를 제공하는 기본해로 사용될 수 있다.

• Journal of Electrical Engineering and Technology
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• 제1권1호
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• pp.101-105
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• 2006

In this paper, a disk-type ultrasonic motor using a combination of radial and bending vibration modes is newly designed and fabricated. The characteristics of the test motor are also measured. By means of traveling elastic wave induced at the surface of circumference of the elastic disk, a steel bar in contact with the surface of circumference of the elastic disk bonded onto the piezoelectric ceramic disks is driven in both directions by changing the sine and cosine voltage inputs. The stator of the motor is composed of two sheets of piezoelectric ceramic disks to bond onto both surfaces of an elastic disk, respectively. As a result, the diameter of the elastic body is increased and the resonant frequency is decreased. The resonant frequency of the stator is about 92 kHz, which is composed with piezoelectric ceramic disks of 28 mm in diameter and 2 mm in thickness, and an elastic body of 32 mm in diameter and 2 mm in thickness. A driving voltage of 20 VPP Produces 200 rpm with a torque of 1Nm and an efficiency of about 10%.

• Journal of Applied Biological Chemistry
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• 제44권4호
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• pp.163-166
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• 2001

Piezoelectric (PZ) crystal biosensor system was used to detect the DNA of food pathogenic Listeria monocytogenes. L. monocytogenes-specific DNA was multiplied via the polymerase chain reaction using LM1 oligonucleotide (5'-TTACGAATTAAAAAGGAGCG-3') and LM2 oligonucleotide (5'-TTAAATCAGCAGGGGTCTTT-3') as primers. DNA fragment of 161 bp, which was specific only for L. monocytogenes, was observed. To obtain a large amount of single-stranded DNA containing an SH group used for coupling to the gold electrode chemisorptively, LM1 oligonucleotide containing a mercaptohexyl group was utilized as a single strand PCR primer. The PCR product was immobilized onto the gold electrode of PZ crystal, and hybridization was monitored in quartz crystal microbalance (QCM) system by injecting the antisense single-stranded DNA of 161 nucleotides obtained via the single strand PCR using the unmodified LM2 primer. Approximately 70 Hz of frequency drop was observed in the QCM system in the case of two consecutive injections of $5{\mu}g$ of the antisense single-stranded DNA.

• Smart Structures and Systems
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• 제16권5호
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• pp.781-806
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• 2015

A unified formulation of finite layer methods (FLMs), based on the Reissner mixed variational theorem (RMVT), is developed for the three-dimensional (3D) coupled electro-elastic analysis of simply-supported, functionally graded piezoelectric material (FGPM) plates with open- and closed-circuit surface conditions and under electro-mechanical loads. In this formulation, the material properties of the plate are assumed to obey an exponent-law varying exponentially through the thickness coordinate, and the plate is divided into a number of finite rectangular layers, in which the trigonometric functions and Lagrange polynomials are used to interpolate the in- and out-of-plane variations of the primary field variables of each individual layer, respectively, such as the elastic displacement, transverse shear and normal stress, electric potential, and normal electric displacement components. The relevant orders used for expanding these variables in the thickness coordinate can be freely chosen as the linear, quadratic and cubic orders. Four different mechanical/electrical loading conditions applied on the top and bottom surfaces of the plate are considered, and the corresponding coupled electro-elastic analysis of the loaded FGPM plates is undertaken. The accuracy and convergence rate of the RMVT-based FLMs are assessed by comparing their solutions with the exact 3D piezoelectricity ones available in the literature.

• 대한기계학회논문집A
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• 제36권6호
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• pp.665-672
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• 2012

면외 기계적 하중 및 면내 전기적 하중하의 횡등방성 이종 압전재료에 대한 계면균열문제를 해석하였다. 복소함수를 도입하여 문제를 수식화 하고, 이로부터 Hilbert 문제를 구성하였다. Hilbert 문제를 풀므로써, 일반해를 얻었다. 일반해를 사용하여, 반무한 균열 혹은 한 개 유한균열 및 두 개 유한균열에 대한 폐형 해를 각각 구하였다. 이때 하중은 한 개의 집중 기계하중 및 전기적하중이 균열면에 작용한다. 이 문제는 기하조건만 동일하면, 임의의 하중에 대해서도 해를 얻을 수 있는 Green 함수로서 사용될 수 있다.

• 한국전기전자재료학회논문지
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• 제33권5호
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• pp.380-385
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• 2020

Over the past decade, small robots have been of particular interest in the engineering field. Among the various types of small robots, biomimetic robots, which mimic animals and insects, have been developed for special activities in areas where humans cannot physically access. The optimal motion of a walking robot can be determined by the characteristics of the traversed surface (e.g., roughness, curvature, slope, materials, etc.). This study proposes three types of piezoelectric structures using different driving mechanisms, depending on the application range of the small walking robots. Dynamic modeling using computer-aided engineering optimized the shape of the robot to maximize its moving characteristics, and the results were also verified through its fabrication and experimentation. Three types of robots, named by their actuator shapes as I, π, & T-shape, were proposed regarding application for small scale ambulatory robots to different terrain conditions. Among these, the T-shaped robots were shown to have a wide range of speeds (from 2 mm/s up to 255 mm/s) and good carrying capacity (up to 10 g at 50 mm/s) through driving experiments. Based on this study, we proposed possible application areas for the three types of walking robot actuators.

• 한국정보통신학회논문지
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• 제8권8호
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• pp.1818-1827
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• 2004

본 논문에서는 압전평면판에 홈을 파 형성한 (equation omitted)형 선형배열음원과 최적화 알고리즘을 조합한 적응 지향성합성 시스템의 2차원 지향성합성 문제를 수치적으로 검토하였다. 임의로 설정한 목적 지향성을 실현하기 위하여 먼저, 선형배열 진동자의 최적 진동 변위량은 최적화 알고리즘인 DFP (Davidon-Fletcher-Powell) 법을 이용하여 계산하고, 다음에, 계산된 진동 변위량을 구동하기 위한 최적 전위의 계산은 유한요소법과 DFP법을 이용하여 행했다. 또한, 유한요소법을 이용하여 (equation omitted)형 압전 트랜스듀서의 2차원 진동해석을 행했다.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1999년도 학술발표대회 논문집 제18권 1호
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• pp.218-223
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• 1999

A piezoelectric flextentional deep-water sonar transducer has been simulated using a coupled FE-BEM. The dynamics of the sonar transducer is modelled in three dimensions and is analyzed with extern리 electrical excitation conditions as well as external acoustic pressure loading conditions. Different results are available such as steady-state frequency response for RX and TX, displacement modes, directivity patterns, back-scattering patterns, resonant frequencies, bandwidths, quality factors, transmitting voltage (TV) responses, input receiving sensitivity (RS) responses. White the present barrel-stave typed sonar transducer of the piezoelectric material is being simulated, the external surface of the transducer is modified in order to allow the same water pressure to be applied to the inner and the outer surfaces of the transducer. With this modification for deep-water application, the resonance frequency of the modified flextentional sonar transducer becomes much lower than that of the unmodified flextentional sonar transducer. The results of the present sonar transducer modelling are also compared with those of a commercial package such as ATILA.