• 대한의용생체공학회:의공학회지
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• 제29권2호
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• pp.114-121
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• 2008

Within 2 to 5 months after stroke, patients recover variable degrees of function, depending on the initial deficit. An impaired hand function is one of the most serious disability in chronic stroke patients. Therefore, to evaluate the extent of motor dysfunction in the hemiplegic hand is important in stroke rehabilitation. In this paper, motor recoveries in 8 chronic stroke patients with Fugl-Meyer (FM) and white matter changes before and after the training program with a designed bilateral symmetrical arm trainer (BSAT) system were examined. The training was performed at 1 hr/day, 5 days/week during 6weeks. In all patients, FM was significantly improved after the 6-week training. Diffusion tensor imaging (DTI) results showed that tractional anisotropy ratio (FAR) and fiber tracking ratio (FTR) in the posterior internal capsule were significantly increased after the training. It seemed that the cortical reorganization was induced by the 6 week training with the BSAT. In all parameters proposed this study, a significant correlation was found between these parameters (FAR and FTR) and motor recoveries. This study demonstrated that DTI technique could be useful in predicting motor recovery in chronic hemiparetic patients.

• 한국광학회지
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• 제14권6호
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• pp.588-593
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• 2003

지능형 구조물에서의 진동 등과 같이 주파수가 1 KHz에 이르는 물리량을 고감도로 측정할 수 있는 광섬유센서를 위한 신호 처리기를 구현하기 위하여 광섬유자이로스코프에 적용되었던 전디지털 위상추적신호처리(ADPT)를 교류량 측정용(다이나믹)으로 변경하여 설계하였다. 구현된 다이나믹 ADPT 신호처리기를 광섬유 Mach-Zehnder간섭계에 적용하여 성능을 평가한 결과 ADPT신호처리방식의 한계인 -50 ㏈에 가까운 전고조파 왜율을 가짐을 확인하였다.

• Journal of the Optical Society of Korea
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• 제14권1호
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• pp.1-13
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• 2010

This paper describes a development of a fiber optic common-path optical coherence tomography (OCT) based imaging and guided system that possess ability to reliably identify optically transparent targets that are on the micron scale; ability to maintain a precise and safe position from the target; ability to provide spectroscopic imaging; ability to imaging biological target in 3-D. The system is based on a high resolution fiber optic Common-Path OCT (CP-OCT) that can be integrated into various mini-probes and tools. The system is capable of obtaining >70K A-scan per second with a resolution better than $3\;{\mu}m$. We have demonstrated that the system is capable of one-dimensional real-time depth tracking, tool motion limiting and motion compensation, oxygen-saturation level imaging, and high resolution 3-D images for various biomedical applications.

• 한국광학회지
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• 제13권5호
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• pp.377-383
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• 2002

개회로 구성의 FOG용 All-Digital Closed Loop(ADCL) 신호처리기는 종래의 아날로그 방식의 위상추적 신호처리를 디지털로 구현한 것으로 안정화기를 채용하지 않고 이를 FOG에 적용하였을 때 0.26$\mu$rad/$^{\circ}C$의 온도의존성을 가지기 때문에 중급 이상의 FOG(fiber optics gyroscope)용 신호처리기로서는 문제가 있다. 온도드리프트는 위상변조를 위해 사용되는 위상변조기의 변조진폭과 위상지연의 온도드리프트에 의해 발생하는 것으로 FOG의 출력에서 위상변조신호의 고조파 성분의 비를 일정하게 함으로 써 광섬유 위상변조기의 동작을 안정화하여 FOG의 드리프트를 측정 불가한 수준으로 줄일 수 있었다.

• Composites Research
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• 제27권2호
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• pp.59-65
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• 2014

대부분의 에너지는 전세계적으로 제한되어 있는 석유, 석탄, 천연가스 등 주로 화석연료로부터 얻어지고 있다. 최근, 고유가, 석유자원의 고갈, 기후변화 등이 신재생에너지를 포함한 비화석 연료가 세계적으로 주목을 받고 있는 이유 중의 하나이다. 이 연구에서는 고비강성 및 비강도, 고내부식성 및 내화학성 등을 장점으로 갖고 있는 펄트루젼 FRP(PFRP)를 사용하였다. 따라서 부유식 구조물의 설계와 시공을 위해서는 PFRP 재료가 우선적으로 선택될 수 있다. 추적식 수상 태양광발전 구조물의 설계는 유한요소해석 결과를 사용하여 수행되었으며, 구조물은 조립되어 수상에 설치되었다. 구조물을 설치하기 전에 안전성 문제를 유한요소법을 사용하여 검토하였으며, 그 결과 설계, 제작, 시공된 구조물은 외적으로 작용된 하중을 지지하는데 충분히 안전함을 알 수 있었다.

• 한국환경과학회지
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• 제28권5호
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• pp.521-526
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• 2019

In this study, a solar light collector that collects and transmits solar light required for crop production in a closed plant production system was developed. The solar light collector consisted of a Fresnel lens for collecting solar light, and a tracking actuator for tracking solar light from sunrise to sunset to increase the light collection efficiency. The optical fiber that transmitted solar light was made of Glass Optical Fiber (GOF), and it had an excellent optical transmission rate. After collecting the solar light, the amount of light was measured at 5, 10, 15, 20, 25, and 30 cm distances from the GOF through the darkroom by using a light sensor logger connected to a quantum and pyranometer sensor. Compared with solar light, the light intensity of pyranometer sensor measured at 5 cm was 114% higher than solar light, and 61% at 10 cm. In addition, it was observed that it is possible to transmit the necessary amount of light for growing crops up to about 15 cm (as over 22%) through GOF. Therefore, adding diffusers to the solar light collector should be expected to replace artificial light in plant factories or plug seedlings nurseries for leafy vegetables. More studies on the solar light collection devices and the light transmission devices that have high light collection efficiency should be conducted.

• 전기전자학회논문지
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• 제20권4호
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• pp.454-458
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• 2016

일반적으로 원단 후가공시 원단의 가장자리를 핀으로 고정하게 되는데, 이때 원단의 고정 부분의 흠집으로 인해 감긴 원단의 포장 보관 시 변사부분이 부풀어 올라 전체적으로 원단의 변형이 발생한다. 원단의 변형 및 손상은 섬유제품의 품질 저하로 이어지기 때문에 원단 변사부분의 검출은 원단 마무리 가공에서 반드시 필요하다. 본 연구에서는 원단제조시 제품의 품질을 좌우하는 자동 변사 커팅(auto selvage cutting)시스템에 사용하는 비접촉식 변사검출 센서를 연구하였다. 이를 위해 32개의 센서를 2.5mm 간격으로 배열하여 감지하는 센서시스템을 개발하였고 이변사검출센서 시스템으로 실제 변사 검출이 가능한 것을 실험으로 확인 하였다.

• The Journal of Korean Physical Therapy
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• 제25권5호
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• pp.260-265
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• 2013

Purpose: This study was conducted in order to evaluate the quantitative effectiveness of region of interest (ROI) setting in MR-DTI analysis with and without fMRI activation results. Methods: Ten right-handed normal volunteers participated in this study. DTI and fMRI datasets for each subject were obtained using a 1.5T MRI system. For neural fiber tracking, ROIs were drawn using two methods: The drawing points were located in the fMRI activation areas or areas randomly selected by users. In this study, the neural fiber tract targeted the corticospinal tract (CST) Quantitative analyses were performed and compared. The pixel numbers passing through the fiber tract in the individual brain volume were counted. The ratios between the ROI pixel numbers and the extracted fiber pixel numbers, and the ratios between the fiber pixel numbers and the whole-brain pixel numbers were also calculated. Results: According to our results, extracted CST fiber tract in which the ROI was drawn with fMRI activation areas showed higher distribution than drawing the ROI by users' hands. In addition, the quantitatively measured values represented higher pixel distribution: The counted average pixel numbers were 4553.8 and 1943.3. The average ratios of the ROI areas were 33.87 and 22.52. The average percentages of the individual whole-brain volume numbers were 2.06 and 0.87. Conclusion: Results of this study appear to indicate that use of this method can allow for more objectives and significant for study of the recovery of neural fiber mechanisms and brain rehabilitation.

• 제어로봇시스템학회논문지
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• 제7권9호
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• pp.741-748
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• 2001

In this paper, we propose a method of tracking and capturing a moving object by a mobile robot. The position of the moving object is acquired from the relation through color-based image information from a 2-DOF active camera mounted on the mobile robot. The direction and rotational angular velocity of the moving object are estimated using a state estimator. A Kalman fiber is used as the state estimator for taking characteristics of robustness against noises and uncertainties included in the input data. After estimating the trajectory of the moving object, we decide on the optimal trajectory and plan the motion of the mobile robot to capture the target object within the shortest distance and time. The effectiveness of the proposed method is demonstrated by the simulations and experiments.

• Smart Structures and Systems
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• 제19권6호
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• pp.625-631
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• 2017

In the fields of civil engineering and seismology, it is essential to detect and tracking the vibrations, and the fiber Bragg gratings (FBGs) are typically used as sensors to measure vibrations. Where, one of the most popular and detailed approaches to use FBGs as vibration sensors involves the use of cantilever beam designs, which adds a mass to measure low and moderate frequencies (from 20 Hz up to 1 kHz) with high sensitivities (greater than 10 pm/g). The design consists of a bending strain in the cantilever that is simultaneously transferred to the FBG, resulting in a shift in the wavelength that is proportional to the strain experienced by the cantilever. In this work, we present the experimental results of a vibration sensor design using a cantilever beam to generate an axial uniform strain in the FBG in-line with the vertical axis, which modifies the cantilever's natural frequency that allows the sensor to have a wide frequency broadband without losing sensitivity. This sensor achieved a sensitivity of about 339 pm/g and a natural frequency of 227.3 Hz. The presented design compared with the traditional cantilever beam-based FBG vibration sensors, has the advantages of a simple design for detection on vibration-sensitive structures and its physical parameters can be easily modified in order to satisfy the requirements of the desired vibration measurements.