• 한국전자파학회논문지
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• 제14권7호
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• pp.699-704
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• 2003

레이다기법을 이용한 마이크로파 Reflectometry를 비균질 매질의 밀도 특성을 조사하기 위한 비파괴검사 장치로 응용하기 위한 시스템 특성을 연구하였다. 마이크로파 Reflectometry로 비균질 매질을 조사하기 위해서는 대상에 따른 시스템의 하드웨어 구성이 최적화되어야 하며, 각 시스템에서의 소신호 반응특성이 이해되어야만 전체적인 시스템 해법을 제공하는 것이 된다. 그 중에서 플라즈마 연구분야에 응용하기 시작한 것은 비교적 최근의 일로서 그 활용도가 점차 증가하고 있는 경향이다. 조사하는 대상의 특성에 따른 시스템의 구성을 이해하고, 파동수 및 밀도 섭동에 관한 시스템의 특성을 조사하기 위한 장치를 제안하며, 실험적 방법의 결과와 1차원 파동방정식을 이용한 수치해석적 결과를 비교 검증하였다.

• Journal of Mechanical Science and Technology
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• 제17권9호
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• pp.1324-1331
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• 2003

A bushing is a device used in automotive suspension systems to cushion the force transmitted from the wheel to the frame of the vehicle. A bushing is essentially a hollow cylinder which is bonded to a solid metal shaft at its inner surface and a metal sleeve at its outer surface. The shaft is connected to the suspension and the sleeve is connected to the frame. The cylinder provides the cushion when it deforms due to relative motion between the shaft and sleeve. The relation between the force applied to the shaft or sleeve and its deformation is nonlinear and exhibits features of viscoelasticity. An explicit force-displacement relation has been introduced for multi-body dynamics simulations. The relation is expressed in terms of a force relaxation function and a method of determination by experiments on bushings has been developed. Solutions allow for comparison between the force-displacement behavior by experiments and that predicted by the proposed method. It is shown that the predictions by the proposed force-displacement relation are in very good agreement with the experimental results.

• Journal of Mechanical Science and Technology
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• 제17권9호
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• pp.1268-1275
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• 2003

In this paper, a compact 3-DOF mobile microrobot with sub-micron resolution is presented. It has many outstanding features : it is as small as a coin ; its precision is of sub-micrometer resolution on the plane ; it has an unlimited travel range ; and it has simple and compact mechanisms and structures which can be realized at low cost. With the impact actuating mechanism, this system enable both fast coarse motion and highly precise fine motion with a pulse wave input voltage controlled. The 1 -DOF impact actuating mechanism is modeled by taking into consideration the friction between the piezoelectric actuator and base. This modeling technique is extended to simulate the motion of the 3-DOF mobile robot. In addition, experiments are conducted to verify that the simulations accurately represent the real system. The modeling and simulation results will be used to design the model-based controller for the target system. The developed system can be used as a robotic positioning device in the micromanipulation system that determines the position of micro-sized components or particles in a small space, or assemble them in the meso-scale structure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.415-419
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• 2003

An elastomeric bushing is a device used in automotive suspension systems to reduce the load transmitted from the wheel to the frame of the vehicle. A bushing is an elastomeric hollow cylinder which is bonded to a solid steel shaft at its inner surface and a steel sleeve at its outer surface. The relation between the load applied to the shaft or sleeve and the relative deformation of elastomeric bushing is nonlinear and exhibits features of viscoelasticity. A load-displacement relation for elastomeric bushing is important for dynamic numerical simulations. A boundary value problem for the bushing response leads to the load-displacement relation which requires complex calculations. Therefore, by modifying the constitutive equation for a nonlinear viscoelastic incompressible material developed by Lianis, the data for the elastomeric bushing material was obtained and this data was used to derive the new load-displacement for radial response of the bushing. After the load relaxation function for the bushing is obtained from the step displacement control test, Pipkin-Rogers model was developed. Solutions were allowed for comparison between the results of Modified Lianis model and those of the proposed model. It is shown that the proposed Pipkin-Rogers model is in very good agreement with Modified Lianis model.

• Smart Structures and Systems
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• 제18권4호
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• pp.801-818
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• 2016

To estimate structural displacement, a visually servoed paired structured light system (ViSP) was proposed in previous studies. The ViSP is composed of two sides facing each other, each with one or two laser pointers, a 2-DOF manipulator, a camera, and a screen. By calculating the positions of the laser beams projected onto the screens and rotation angles of the manipulators, relative 6-DOF displacement between two sides can be estimated. Although the performance of the system has been verified through various simulations and experimental tests, it has a limitation that the accuracy of the displacement measurement depends on the alignment of the laser pointers. In deriving the kinematic equation of the ViSP, the laser pointers were assumed to be installed perfectly normal to the same side screen. In reality, however, this is very difficult to achieve due to installation errors. In other words, the pose of laser pointers should be calibrated carefully before measuring the displacement. To calibrate the initial pose of the laser pointers, a specially designed jig device is made and employed. Experimental tests have been performed to validate the performance of the proposed calibration method and the results show that the estimated displacement with the initial pose calibration increases the accuracy of the 6-DOF displacement estimation.

• 대한전자공학회논문지SD
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• 제46권10호
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• pp.16-24
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• 2009

Independent-Gate-Mode Double-Gate(IGM-DG) MOSFET는 기존의 DG-MOSFET의 3-terminal 소자구조가 갖고 있는 한계에서 벗어나 front-gate와 back-gate를 서로 다른 전압으로 구동하는 것이 가능하다. IGM-DG를 이용함으로써 4번째 단자의 자유도에 의해 회로설계가 간단해 질 뿐 아니라, 집적도를 향상시킬 수 있는 장점을 가진다. 본 논문에서는 IGM-DG MOSFET를 사용하여 RF 수신단을 설계하였고, HSPICE 시뮬레이션을 통해 회로성능을 검증하고 소자의 특성변화에 따른 최적의 회로설계 방향을 제시하였다.

• 대한전자공학회논문지SD
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• 제45권2호
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• pp.1-6
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• 2008

Long-channel Asymmetric Double-Ga(ADG) MOSFET의 해석적 문턱전압 모델을 제시한다. 본 모델은 채널 도핑과 채널의 양자효과까지 고려하였으며 더 나아가 문턱전압 영역에서 potential 분포의 선형특성을 이용하여 기존의 모델보다 간단하면서도 정확한 접근을 가능하게 하였다. 개발한 모델의 정확도는 다양한 실리콘 필름의 두께, 채널 도핑, 그리고 산화막 두께 변화에 대하여 numerical 시뮬레이션 결과와 비교하여 검증하였다.

• 조명전기설비학회논문지
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• 제26권7호
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• pp.1-8
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• 2012

In this paper, we improved the light extraction efficiency by structural change of LEDs on conventional LEDs. We simulated the LEDs light emission as functions of LED side wall angle, various refractive indices the geometrical structures and analyzed the condition improved the light efficiency. We present the results of experimerns and simulations for light output power from LEDs for various refractive indices and the geometrical structures of the LED encapsulants. When the side wall angle range was from 40[$^{\circ}$] to 30[$^{\circ}$], the LED emission increased. LED side wall angle onto LED using the simulation system with a fine tuning of the structure of the LEDs side wall angle is fabricated. Additionally, we changed the side wall angle of LED package with spherical structure and flat structure. The result of spherical structure ray tracting is higher compared with flat structure about 14[%].

• Maxillofacial Plastic and Reconstructive Surgery
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• 제37권
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• pp.44.1-44.6
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• 2015

Background: The present study introduces the design and fabrication of a simple surgical guide with which to perform genioplasty. Methods: A three-dimensional reconstruction of the patient's cranio-maxilla region was built, with a dentofacial skeletal model, then derived from CT DICOM data. A surgical simulation was performed on the maxilla and mandible, using three-dimensional cephalometry. We then simulated a full genioplasty, in silico, using the three-dimensional (3D) model of the mandible, according to the final surgical treatment plan. The simulation allowed us to design a surgical guide for genioplasty, which was then computer-rendered and 3D-printed. The manufactured surgical device was ultimately used in an actual genioplasty to guide the osteotomy and to move the cut bone segment to the intended location. Results: We successfully performed the osteotomy, as planned during a genioplasty, using the computer-aided design and computer-aided manufacturing (CAD/CAM) surgical guide that we initially designed and tested using simulated surgery. Conclusions: The surgical guide that we developed proved to be a simple and practical tool with which to assist the surgeon in accurately cutting and removing bone segments, during a genioplasty surgery, as preoperatively planned during 3D surgical simulations.

• 한국군사과학기술학회지
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• 제21권3호
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• pp.370-378
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• 2018

The mission data in missile systems should be quickly and reliably transmitted from a mission transmission device to a guidance control unit. The MIL-STD-1553B is one of the reliable communication standards, but its bit rate is generally limited to 1Mbps due to the intrinsic properties of its electrical design. Therefore, the bus controller needs to be optimized to efficiently transmit the mission data on the inevitably limited bit rate. This paper proposes an analytical approach based on sampling-based optimization methods to maximize the data throughput without data loss. The proposed approach was evaluated in the simulations with the data transmission model for the MIL-STD-1553B communication system. The results of the proposed methods were applied to a real-time system and showed that the proposed method was successfully performed.