• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.250-253
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• 2001

Recently, based on the smart structure concept, optical fiber sensors have been increasingly applied to monitor the various engineering and civil structural components. Repairs based on adhesively bonded fiber reinforce composite patches are more structurally efficient and much less damaging to the parent structure than standard repairs based on mechanically fastened metallic patches. As a result of the high reinforcing efficiency of bonded patches fatigue cracks can be successfully repaired. However, when such repairs are applied to primary structures, it is needed to demonstrate that its loss can be immediately detected. This approach is based on the "smart patch" concept in which the patch system monitors its own health. The objective of this study is to evaluate the potentiality of application of transmission-type extrinsic Fabry-Perot optical fiber sensor (TEFPI) to the monitoring of crack growth behavior of composite patch repaired structures. The sensing system of TEFPI and the data reduction principle for the detection of crack detection are presented. Finally, experimental results from the tests of center-cracked-tension aluminum specimens repaired with bonded composite patch is presented and discussed.

• Smart Structures and Systems
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• 제7권2호
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• pp.103-116
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• 2011

This paper is concerned with the trajectory tracking and vibration suppression of a single-link flexible arm by using piezoelectric materials. The dynamics of a single flexible arm with PZT patches as sensor and actuator is derived using extended Hamilton's principle. Resulting equations show that the coupled beam dynamics including beam vibration and its rigid in-plane rotation takes place in two different time scales. By using singular perturbation theory, the system dynamics is divided into two subsystems. Then, a composite control scheme is elaborated that makes the orientation of the arm track a desired trajectory while suppressing its vibration. The proposed controller has two parts: one is a tracking controller designed for the slow (rigid) subsystem, and the other one is a stabilizing controller for the fast (flexible) subsystem. The outputs considered for the system are angular position of the hub and voltage of the sensor mounted on the structure. To avoid requiring further measurements of beam vibration and also angular velocity of the hub for the fast and slow control laws, respectively, two sliding mode observers for estimating the unknown states are also designed.

• 한국컴퓨터정보학회논문지
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• 제24권1호
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• pp.9-23
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• 2019

In this paper, we propose a layer structure of a pest image classifier model using CNN (Convolutional Neural Network) and background removal image processing algorithm for improving classification accuracy in order to build a smart monitoring system for pine wilt pest control. In this study, we have constructed and trained a CNN classifier model by collecting image data of pine wilt pest mediators, and experimented to verify the classification accuracy of the model and the effect of the proposed classification algorithm. Experimental results showed that the proposed method successfully detected and preprocessed the region of the object accurately for all the test images, resulting in showing classification accuracy of about 98.91%. This study shows that the layer structure of the proposed CNN classifier model classified the targeted pest image effectively in various environments. In the field test using the Smart Trap for capturing the pine wilt pest mediators, the proposed classification algorithm is effective in the real environment, showing a classification accuracy of 88.25%, which is improved by about 8.12% according to whether the image cropping preprocessing is performed. Ultimately, we will proceed with procedures to apply the techniques and verify the functionality to field tests on various sites.

• 제어로봇시스템학회논문지
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• 제20권5호
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• pp.570-577
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• 2014

This paper describes the design of a force applying system for a smart phone curved glass molding system and its characteristic test. The force applying system is composed of a motor and gear, a rectilinear movement structure, a force sensor, an LVDT (Linear Variable Differential Transformer) sensor, an up and down moving block, and so on. The system precisely controls the applying force and time to the plane glass because the glass can be easily destroyed under applied force, and can be bent imperfectly. As a result of the characteristic test, the curved glass can be manufactured using this system, and the holding time under 0N force, the applying force to the plane glass, the time for applying from 0N to maximum force, and the holding time under maximum force at the manufacture feasible temperature $620^{\circ}C$ were found.

• 대한공간정보학회지
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• 제25권1호
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• pp.47-54
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• 2017

최근 unmanned aerial vehicle(UAV)를 이용하여 영상을 취득하고 지도제작 및 3차원 형상을 구축하는 연구들이 활발히 이루어지고 있다. 본 연구에서는 영상정합(image matching) 기술을 이용하여 3차원 형상을 재현하고, 형상 변화가 있을 경우 이를 탐지하여 면적 및 부피를 계산하는 방법론을 제시하는 실험으로 측정 정확도를 평가하였다. 이를 위해 모의 구조물을 구축하여 형상변화 전 후의 UAV 영상을 취득하고, 영상정합 결과물인 포인트 데이터의 비교를 위해 변화 전 데이터는 격자 형태로 변환하여 높이 값을 비교하였다. 실험 결과, 제안된 방법은 가로 세로 30cm 이상의 형상변화는 매우 높은 정확도로 면적 및 부피를 계산하였으나, 그 이하의 형상변화는 아직 영상정합기술의 한계에 기인하여 적용이 어려운 것으로 검증되었다. 하지만 제안한 방법론은 불법건축물 판별, 구조물의 일정규모 이상 피해의 정량적 분석 및 관리 등에 충분히 활용 가능할 것으로 생각된다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.550-555
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• 2007

This paper is concerned with the active vibration control of building structure by means of the active tuned mass damper and the modified positive position feedback controller. To this end, one-degree-of-freedom spring-mass-damper system equipped with ATMD is considered. The stability condition for the addressed system when applying the proposed PPF controller is derived by Routh-Hurwitz stability criterion. The stability condition shows that the modified PPF controller is absolutely stable if the controller gain is positive, so that the modified PPF controller can be used without difficulty. Theoretical study shows that the modified PPF controller can effectively suppress vibrations as the original PPF controller does in smart structure applications. To investigate the validity of the modified PPF controller, a simple experimental structure with an ATMD system driven by DC motor was built. The modified PPF control algorithm was implemented on Atmel 128 microcontroller. The experimental result shows that the modified PPF controller can also suppress vibrations for the real structure.

• Smart Structures and Systems
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• 제19권6호
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• pp.679-694
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• 2017

The complexity, enlargement and irregularity of structures and multi-directional dynamic loads acting on the structures can lead to unexpected structural behavior, such as torsion. Continuous torsion of the structure causes unexpected changes in the structure's stress distribution, reduces the performance of the structural members, and shortens the structure's lifespan. Therefore, a method of monitoring the torsional behavior is required to ensure structural safety. Structural torsion typically occurs accompanied by displacement, but no model has yet been developed to measure this type of structural response. This research proposes a model for measuring dynamic torsional response of structure accompanied by displacement and for identifying the torsional modal parameter using vision-based displacement measurement equipment, a motion capture system (MCS). In the present model, dynamic torsional responses including pure rotation and translation displacements are measured and used to calculate the torsional angle and displacements. To apply the proposed model, vibration tests for a shear-type structure were performed. The torsional responses were obtained from measured dynamic displacements. The torsional angle and displacements obtained by the proposed model using MCS were compared with the torsional response measured using laser displacement sensors (LDSs), which have been widely used for displacement measurement. In addition, torsional modal parameters were obtained using the dynamic torsional angle and displacements obtained from the tests.

• 한국소음진동공학회논문집
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• 제18권2호
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• pp.224-230
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• 2008

This paper is concerned with the active vibration control of building structure by means of the active tuned mass damper and the modified positive position feedback controller. To this end, one-degree-of-freedom spring-mass-damper system equipped with ATMD is considered. The stability condition for the addressed system when applying the proposed PPF controller is derived by Routh-Hurwitz stability criterion. The stability condition shows that the modified PPF controller is absolutely stable if the controller gain is positive. so that the modified PPF controller can be used without difficulty. Theoretical study shows that the modified PPF controller can effectively suppress vibrations as the original PPF controller does in smart structure applications. To investigate the validity of the modified PPF controller, a simple experimental structure with an ATMD system driven by DC motor was built. The modified PPF control algorithm was implemented on Atmel 128 microcontroller. The experimental result shows that the modified PPF controller can also suppress vibrations for the real structure.

• 한국지진공학회논문집
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• 제9권1호통권41호
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• pp.51-59
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• 2005

본 연구에서는 위의 어려움을 해결하기 위해, 스마트 수동제어 시스템을 제안하였다. 스마트 수동제어 시스템은 MR댐퍼와 EMI시스템으로 구성되며, EMI시스템은 영구자석과 솔레노이드 코일로 이루어진다. EMI시스템은 MR댐퍼의 왕복운동에너지를 전기에너지로 변환하므로, 스마트 수동제어 시스템은 외부 전원 없이 외부하중에 따라 댐퍼의 점성을 바꾸는 적응성을 갖는다. 따라서 간단하고 효율적인 장치로써, 대형토목구조물에 적용 가능하다. 이의 확인을 위해 예제를 통한 수치해석을 수행하였으며, 스마트 수동제어 시스템이 강진에 대해서는 기존의 반능동 제어 MR댐퍼 시스템 보다 우수한 성능을 보인다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제29회 추계학술대회논문집
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• pp.252-255
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• 2007

최근에 선진국에서 아주 빠른 시간(마이크로 초)에 작동이 되고, 크기가 소형이면서, 많은 케이블과 커넥터를 사용하지 않는 Smart Bus Controller(SCB) 기법을 이용한 초소형/초고속(스마트) 점화기술에 집중적인 연구를 진행하고 있는 실정이다. 이와 같은 점화기술은 기존의 점화장치에서 사용하던 케이블과 커넥터 공간을 최소화 할 수 있게 MEMS 기법을 이용하여 케이블과 커넥터 장치를 설계 제작하였고, 저 용량/저 전류에서 작동할 수 있는 플라즈마를 이용한 케이블과 커넥터 장치를 설계 제작하였고, 저 용량/저 전류에서 작동할 수 있는 플라즈마를 이용한 초고속 착화장치를 사용하여 전류와 전압(배터리) 크기와 용량도 많이 감소시킬 수 있다. 스마트 파이로테크닉스 점화장치 개발에는 간결한 회로 점화통제장치 설계 및 제작, 빠른 점화작동시간을 가능하게 하는 플라즈마형 초고속 착화장치 설계 및 특성연구가 필요하다. 본 연구에서는 플라즈마형 초고속 착화장치의 특성연구에 대해 기술하였다.