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유욱재,장경원,서정기,Ji Yeon Heo,Jin Soo Moon,Jang-Yeon Park,이봉수 한국광학회 2010 Current Optics and Photonics Vol.14 No.3
In this study, we have fabricated two types of non-invasive fiber-optic respiration sensors that can measure respiratory signals during magnetic resonance (MR) image acquisition. One is a nasal-cavity attached sensor that can measure the temperature variation of air-flow using a thermochromic pigment. The other is an abdomen attached sensor that can measure the abdominal circumference change using a sensing part composed of polymethyl-methacrylate (PMMA) tubes, a mirror and a spring. We have measured modulated light guided to detectors in the MRI control room via optical fibers due to the respiratory movements of the patient in the MR room, and the respiratory signals of the fiber-optic respiration sensors are compared with those of the BIOPAC® system. We have verified that respiratory signals can be obtained without deteriorating the MR image. It is anticipated that the proposed fiber-optic respiration sensors would be highly suitable for respiratory monitoring during surgical procedures performed inside an MRI system.
Silver Halide 광섬유를 이용한 의료용 비접촉식 온도 센서 개발
유욱재,조동현,장경원,정순철,탁계래,이봉수,Yoo, Wook-Jae,Cho, Dong-Hyun,Jang, Kyoung-Won,Chung, Soon-Cheol,Tack, Gye-Rae,Lee, Bong-Soo 대한의용생체공학회 2006 의공학회지 Vol.27 No.6
We have developed a noncontact temperature sensor using a silver halide optical fiber. The infrared collimator and focus head are connected both ends of a silver halide optical fiber with SMA connectors and used to collimate radiations of a heat source and to focus them to infrared sensors such as a pyroelectric sensor and a thermopile sensor, respectively. The relation ships between the temperatures of a heat source and the output signals of the infrared sensors are determined to measure the surface temperature of a heat source. The measurable temperature range is from 25 to $60^{\circ}C$. It is expected that a noncontact temperature sensor using a silver halide optical fiber can be developed for medical usages such as temperature monitoring during hyperthermia, cryosurgery, laser surgery and diagnostic procedure based on the results of this study.
가드레일 지주 간격 및 두께 변화가 트럭 충돌에 의한 동적 거동에 미치는 영향
유욱재,김규동,우영호,이상열 한국복합신소재구조학회 2016 복합신소재구조학회 학술발표회 Vol.2016 No.04
A finite element simulation study was performed to determine influences of different post spaces and thicknesses of crash barriers on the dynamic behaviors due to truck crash. Accuracy of the simulation was verified using qualitative and quantitative comparisons. Based on in-depth examination of crash simulation recordings, energy distributions occurred in the barrier against the car are determined. In this paper, the existing finite element crash analysis of barriers using the LS-DYNA program is further extended to study the dynamic response of the barrier with various geometries of the guardrail. The numerical results for various parameters are verified by comparing different models.
Embedded Infrared Fiber-optic Sensor for Thermometry in a High Temperature/Pressure Environment
유욱재,장경원,문진수,한기택,전다영,이봉수,박병기 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.9
In this study, we developed an embedded infrared fiber-optic temperature sensor using two identical silver halide optical fibers for thermometry in high temperature/pressure and water-chemistry environments. The performance of the fabricated temperature sensor was assessed in an autoclave that was filled with an aqueous coolant solution containing boric acid and lithium hydroxide. We carried out real-time monitoring of the infrared radiation emitted from the signal and reference probes according to temperature variation over a temperature range from 95 to 225 ℃. In order to decide the temperature of the synthetic coolant solution, the difference between the infrared radiation emitted from the two temperature sensing probes was measured. Thermometry with the proposed sensor is immune to any changes of physical conditions and emissivity of a heat source. From the experimental results, the embedded infrared fiber-optic temperature sensor can withstand and normally operate in a high temperature/pressure test loop system corresponding with the coolant system used for nuclear power plant simulation. It is expected that the proposed sensor can be developed to accurately monitor temperature in harsh environments.
Development of Nasal-cavity- and Abdomen-attached Fiber-optic Respiration Sensors
유욱재,장경원,이봉수,서정기,허지연,문진수,박장연 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.61
In this study, we fabricated two types of optical-fiber-based sensors for non-invasive respiratory monitoring. A nasal-cavity-attached respiration sensor can measure the temperature variations of airflow by using a silver-halide optical fiber located in the nasal-cavity, and an abdomen-attached respiration sensor can measure the changes in the abdominal circumference by using a plastic optical fiber. We measured the modulated light beams that are guided to the detectors via optical fibers due to the airflow and to the abdominal movement. In addition, the respiration signals from the fiber-optic respiration sensors are compared with those from the BIOPAC® system.
유욱재,백지윤,조동현,장경원,서정기,허지연,이봉수,조영호,박병기,문주현,Yoo, Wook-Jae,Baek, Ji-Yun,Cho, Dong-Hyun,Jang, Kyoung-Won,Seo, Jeong-Ki,Heo, Ji-Yeon,Lee, Bong-Soo,Cho, Young-Ho,Park, Byung-Gi,Moon, Joo-Hyun 대한의용생체공학회 2009 의공학회지 Vol.30 No.6
In this study, we fabricated a plastic optical fiber based sensor which can monitor the respiration of a patient. The circumference changes of the abdomen were measured using a mirror, a light source and optical detectors because the circumferences of the abdomen could be varied with respiration. The intensity of the reflected lights were measured according to the changes of distance between mirror and plastic optical fiber connected to a light source and a photodiode-amplifier system using a Y-coupler. The respiration signals of fiber-optic sensor system were compared with those of the respiratory and temperature transducers of the $BIOPAC^{(R)}$ system. It is expected that a fiber-optic respiration sensor could be developed for real time respiration monitoring during MRI procedure based on this study.
유욱재,최인용,전광민 대한기계학회 1994 대한기계학회논문집 Vol.18 No.10
The modeling of combustion process is an important part in an engine simulation program. In this study, calculated results using a conventional B-K model and the other model which is called GESIM were compared with experimentally measured data of a three-cylinder spark-ignition engine under wide range of operating conditions. The burn rates calculated from the combustion models were compared with the burn rate calculated from the one-zone heat release analysis that uses measured pressure data as an input data. As a result of the two models' comparison, the GESIM combustion model conformed to be closer to the data acquired from the experiment in wide operating ranges. The GESIM model has been improved by introducing a variable that considers the flame size, the area of flame conacting the piston surface into the model, based on the comparison between the experimental result and the calculated results. The improved combustion model predicts experimental results more precisely than that of GESIM combustion model.