• Investigative Magnetic Resonance Imaging
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• v.20 no.3
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• pp.167-174
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• 2016

Purpose: To identify magnetic resonance imaging (MRI) findings of leukemic infiltration of optic nerve and optic neuritis in leukemic patients with emphasis of clinical findings as reference standard to differentiate them. Materials and Methods: MRI and clinical findings of 7 patients diagnosed as leukemic infiltration of optic nerve (n = 5) and optic neuritis (n = 2) in our institution between July 2006 and August 2015were reviewed retrospectively. In particular, MR imaging findings involved perineural enhancement and thickening of optic nerve and its degree, signal intensity, laterality (unilateral/bilateral), intraconal fat infiltration and its degree, and associated central nervous system abnormalities. Results: Of 5 cases of leukemic infiltration of optic nerve, 4 cases showed positive cerebrospinal fluid (CSF) study for leukemia relapse and 1 case was positive on bone marrow (BM) biopsy only. Moreover, of 5 leukemic infiltration of optic nerve, 2 cases showed the most specific MR findings for leukemic central nervous system involvement including 1 prominent leptomeningeal enhancement and 1 chloroma. However, other MR imaging findings of the patients with leukemic infiltration or optic neuritis such as thickening and perineural enhancement of optic nerves are overlapped. Conclusion: Enhancement and thickening of optic nerve were overlapped MR findings in leukemic infiltration of optic nerve and optic neuritis. Our findings suggest that enhancing optic nerve thickening with associated central nervous system MR abnormality favors the diagnosis of leukemic infiltration of optic nerve, especially in patients with history of acute lymphoblastic leukemia. However, CSF and BM study were required for differentiation between leukemic infiltration of optic nerve and optic neuritis.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.285-285
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• 2009

• Journal of Biomedical Engineering Research
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• v.9 no.1
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• pp.125-130
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• 1988

In the conventional infrared imaging system, complex infrared lens systems are usually used for directing collimated narrow infrared beams into the high speed 2-dimensional optic scanner. In this paper, a simple reflective infrared optic system with a 2-dimensional optic scanner is proposed for the realization of medical infrared thermography system. It has been experimentally proven that the intfrared thermography system composed of the proposed optic system has the temperature resolution of $0.1^{\circ}C$ under the spatial resolution of lmrad, the image matrix size of $256 {\times} 240, $ and tile imaging time of 4 seconds.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.451-454
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• 2006

Fiber optic distributed temperature sensing and thermal line sensor are applied in an observation borehole and a loom deep borehole heat exchanger. For the case of permanently installed system fiber optic DTS is very useful. By comparing with TLS, fiber optic DTS shows good accuracy and reliability. Ground water flow can give influences at heat exchange rate of the heat pump system. According to the hydraulic characteristics and temperature-depth profile, we consider that temperature-depth profile do not seem to be dependent on ground water flow. A permanent installation of fiber optic cable is expected as a reliable temperature measurement technique in a borehole heat exchanger system.

• Journal of the Korean Institute of Navigation
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• v.18 no.4
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• pp.171-178
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• 1994

Fiber optic gyroscopes must be a promising technology that can replace conventional mechanical ones based on the principle of inertia of spinning masses. The advantages of fiber optic gyroscopes over mechanical ones include low cost, light weight, compact size and fast turn-on time. We will apply them to fiber optic gyrocompass for ships. Fiber optic gyrocompass for ships requires the north-seeking accuracy of $15^{\circ}$/hr, earth rotation rate, or better. This article introduces the fiber optic gyroscope as rotation sensor in the fiber optic gyrocompass system for ships that is planed to develop in our laboratory.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.505-510
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• 2002

We have focused on the development of a fiber optic BOTDA (Brillouin Optical Time Domain Analysis) sensor system in order to measure temperature distributed on large structures. Also, we present a feasibility study of the fiber optic sensor to monitor the distributed temperature on a building construction. A fiber optic BOTDA sensor system, which has a capability of measuring the temperature distribution, attempted over several kilometers of long fiber paths. This simple fiber optic sensor system employs a laser diode and two electro-optic modulators. The optical fiber of the length of 1400 m was installed on the surfaces of the building. The change of the distributed temperature on the building construction was well measured by this fiber optic sensor. The temperature changed normally up to 4℃ through one day.

• Journal of Sensor Science and Technology
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• v.15 no.1
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• pp.40-46
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• 2006

This paper presents a novel fiber optic accelerometer system for monitoring vibration of large-size structures. The system is composed of one (or multiple) sensor head, a light control unit and a signal processing unit. The sensing mechanism of the sensor head is based on a novel integration of the moire fringe phenomenon with fiber optics to achieve a robust performance in addition to its immunity to EM interference, easy cabling, and low cost. In this paper, a prototype of the fiber optic accelerometer system has been developed successfully. A low-cost light control unit has been developed to drive the system's optic and electronic components. A unique algorithm has also been developed to derive the sensor's acceleration from the raw signals of the light control unit; it is implemented via a separate signal processing unit. Finally, the shaking table tests successfully demonstrate the performance and the potential of the moire fringe fiber optic sensor system to monitor the health of civil infrastructures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.81-84
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• 2007

In this paper, fiber optic sound and vibration monitoring sensor which is latticed shape structure based on Sagnac interferometer is fabricated and tested in laboratory conditions. To detect external vibrations surface mounted fibers on the latticed steel wire fence with a dimension of 170cm by 180cm is used. To detect external sound frequency the tightened fiber optic itself wire netting fence with a dimension of 50cm by 50cm is used. Experiments for the detection of the excited vibration and sound signals were performed. A small vibrator induced external vibration signal and it is applied to the latticed structure in the range of 100Hz to several kHz. External sound signal applied to the fiber optic sensor net using non-directional sound speaker. The detected optical signals were compared and analyzed to the detected both accelerometer and microphone signals in the time and frequency domain. Based on the experimental results, distributed fiber optic sensor using Sagnac interferometer detected effectively external vibration and sound signal and had a good performance. This system can be expanded to the monitoring of a significant system and to the structural health monitoring system.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.4 no.1
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• pp.7-13
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• 2005

In this paper, we propose the time synchronization module on fiber optic repeater to use optic line delay for obtaining time synchronization between up-link and down-link, in the 2.3 GHz WiBro network using TDD/OFDM (Time Division Duplex/Orthogonal Frequency Division Multiplexing) Generally, when we use fiber optic repeater to remove the shade area, it occurs transmission delay which is caused by optic transmission between RAS (Radio Access Station) and fiber optic repeater and inner delay of fiber optic repeater. Because the WiBro system is adopting a TOO method and there exists the difference of switching time which is caused by these delay between up-link and down-link, it occurs ISI (Inter Symbol Interference), ICI (Inter Carrier Interference). These interference results in the reduction of the coverage. And the inconsistency between Up-Link and Down-Link switching time maybe gives rise to the interruption of communication. In order to prevent these cases, we propose synchronization module using analog optic line delay as the one of synchronizing up-link and down-link. And we propose the consideration factor for the designing time synchronization module and the feature of optic line of analog method. The measurement result of optic line time synchronization module of structure proposed is as follows, the delay error of $0.5{\mu}g$ and the insertion loss value below maximum 4.5dB in range of $0{\sim}40{\mu}s$. These results fully meet the specification of WiBro System.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.640-643
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• 1996

In this paper, a sensitivity of the fiber optic pressure sensor in water is demonstrated. A single mode optical fiber Mach-Zehnder interferometer used to detect the change in optical path length produced by the change of fiber optic strain in water. The sensitivity with this system measured 100.mu.psia through an experiment in the static response.