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문석범(S.B.Mun),이봉수(B.S.Lee),구자예(J.Y.Koo),이장희(J.H.Lee) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_1
Experimental investigation of unsteady impinging D.I. diesel spray on the flat plate has been carried out using photographic technique. Ambient gas density were varied using N2 and Ar gas with chamber pressure of l.lMPa. 2.1MPa. 2.6MPa. As the increase of gas density, the radial penetration is decreased due to the resistance of the ambient gas. As the increase of the gas density, the height of spray is increased due to the increase of entrainment and circulation.<br/>
Evaluation of Image qualify in Super-resolution Image Guide for Ultrathin Endoscope
최원영,오창현,이봉수,Choi W.Y.,Oh C.H.,Lee B.S. The Korea Society of Medical and Biological Engine 2000 의공학회지 Vol.21 No.3
In general. fiber-optic medical endoscopes are made from glass step index (SI) fibers. These endoscopes have limitations in both image quality and mechanical properties. In particular. the image resolution of the SI endoscopes is limited to about 5$\mu$m. In this study the image resolution of plastic graded index (GRIN) super-resolution image guides with pixel sizes from 7 to 2.5 $\mu$m were measured and compared with those of 91ass SI image guides. There is an improvement in resolution of the plastic GRIN image guides as the microfiber diameter is reduced from 7 $\mu$m to 2.5 $\mu$m. The measured resolution of plastic GRIN image guide with 2.5 $\mu$m microfibers is more than a factor of two higher than that of g1ass SI image guide with 5$\mu$m microfibers. This new design of optical systems could have a major impact on a wide array of future optical systems used in defense. industrial, and medical applications. 현재 의료용으로 사용되고 있는 광섬유를 이용한 내시경은 굴절률이 다른 두 가지 유리로써(Step Index SI) 제작되고 있다. 이와 같은 내시경은 취급에 주의하여야 하는 근본적인 재료상의 문제점 외에도 영상 가이드의 최고 분해능이 5$\mu$m으로 제약되고 있는 실정이다. 본 연구에서는 플라스틱을 이용하여 고 영상 분해능($7\mu\;m\~2.5\mu$m)을 가진 미세 내시경(Ultrathin Endoscope)용 영상 가이드의 분해능을 측정하였다. 그 각각의 플라스틱 광섬유 굴절률은 광섬유 중심으로부터 외곽까지 점차 감소하는 특성 (Graded Index GRIN)을 가지고 있다. 플라스틱 GRIN 영상가이드의 분해능 측정 결과. 마이크로 광섬유의 지름이 작아질수록 그 분해능이 증가되었고, 유리를 이용한 SI 영상 가이드 분해능과의 비교 연구 결과, 2배의 분해능을 가진 (2.5$\mu$m) 플라스틱 GRIN 영상가이드 제작이 가능함을 보였다. 이와 같은 플라스틱 GRIN 광섬유 다발은 의료 분야뿐 아니라 국방 및 산업분야의 새로운 광학적 설계에 많은 영향을 줄 것으로 기대된다.
진의덕(E. D. Jin),최진승(J. S. Choi),탁계래(G. R. Tack),이봉수(B. S. Lee),이법이(B. Y. Lee) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월
Recently intradiscal electrothermal therapy is introduced, which is a new and minimally invasive technique for the treatment of discogenic low back pain. This procedure involves the percutaneous threading of a flexible catheter into the disc under fluoroscopic guidance. The catheter, composed of thermal resistive coil, heats the posterior annulus of the disc, causing contraction of collagen fibers and destruction of afferent nociceptors. This study tries to investigate the effects of the important factors of this procedure such as heat source temperature and heat applying time on the temperature distribution within the intervertebral disc. This study utilized both computer simulation and the experiment for the verification of finite element analysis. FE analysis was carried out with ANSYS v7.0 (ANSYS Inc, USA) using 10,980 number of brick element and 12,551 number of node. The functional spinal units of 5 month old swine were used for the experiment and the temperature was monitored using 10 channel temperature measurement device MV200. Through this study, it was able to analyze the temperature range of inner intervertebral disc by two mechanisms which are known to alleviate pain clinically. The results showed that when the heat source temperature was kept up 80 degree for 1,020 seconds, the temperature of inner annulus reached at 45 degree up to the distance of 15.6㎜ from heat source, which explains coagulation of inner annulus by heat. When the same heat source was used, the temperature of inner nucleus reached at 60 degree up to the distance of 9㎜ from heat source, which explains contraction of inner nucleus by heat.
보행시 신발, 속도, 경사도에 따른 동작의 부드러움 차이
최진승(J. S. Choi),탁계래(G. R. Tack),이정한(J. H. Yi),이봉수(B. S. Lee),정순철(S. C. Chung),손상희(S. H. Sohn) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월
The purpose of this study was to evaluate the smoothness of the gait pattern according to shoe, walking speed, and slope. Eleven male university students used three types(running shoes, mounting climbing boots, elevated forefoot walking shoes) of shoes at various walking speeds(1.19, 1.25, 1.33, 1.56, 1.78, 1.9, 2.0, 2.11, 2.33m/s) and gradients (0, 3, 6, 10%) on a treadmill. Three-dimensional motion analysis (Motion Analysis Corp, Santa Rosa, CA, USA) was conducted with 4 Falcon high speed cameras. The results showed that elevated forefoot walking shoes had the lowest value of normalized jerk at the heel, which means that elevated forefoot walking shoes had the smoothest walking pattern at the heel. In contrast, elevated forefoot walking shoes had greater normalized jerk at the center of mass (COM) at most walking speeds, which means that the smoothness of gait pattern at the center of mass is the lowest for the elevated forefoot walking shoes. This movement at the COM might even have a beneficial effect of activating muscles in the back and abdomen more than other shoes.
보행장애 진단을 위한 무릎관절 각도 측정용 광섬유 각도센서
김선근(S. G. Kim),신상훈(S. H. Shin),전다영(D. Jeon),홍승한(S. H. Hong),심혁인(H. I. Sim),장경원(K. W. Jang),유욱재(W. J. Yoo),이봉수(B. Lee) 대한전기학회 2013 전기학회논문지 Vol.62 No.7
In this study, we developed a fiber-optic goniometer for the continuous measurement of knee joint angle which provides important medical information on Alzheimer’s disease. The fiber-optic goniometer is composed of a light-emitting diode (LED), a plastic optical fiber (POF), and a voltage output photodiode (PD). As a sensing part of the fiber-optic goniometer, a unclad fiber with regular intervals of 1 mm was fabricated to improve efficiency of bending loss according to the angle variation of knee joint. The emitting light with a center wavelength of 470 nm from a LED is guided by a POF to the PD, the transmitted light is then attenuated by the bending loss inside the bent POF. The intensity variation of the light transmitted from the POF gives rise to a change in output voltage in the fiber-optic goniometer. Therefore, we measured the real-time output voltage of the proposed fiber-optic goniometer using the unclad fiber according to the knee joint angle. Through the repeated experiments, the fiber-optic goniometer shows that it has a reversibility and a wide measurable angle range.
유욱재 ( Wook Jae Yoo ),서정기 ( Jeong Ki Seo ),장경원 ( Kyoung Won Jang ),문진수 ( Jin Soo Moon ),한기택 ( Ki Tek Han ),박장연 ( Jang Yeon Park ),이봉수 ( Bong Soo Lee ),조승현 ( Seung Hyun Cho ),허지연 ( Ji Yeon Heo ),박병기 ( B 한국센서학회 2011 센서학회지 Vol.20 No.4
A reflection-type fiber-optic pH sensor, which is composed of a pH sol-gel film, plastic optical fibers, a mirror, a light source and a spectrometer, is developed in this study. As pH indicators, a bromthymol blue, a cresol red and a thymol blue are used, and they are immobilized in the sol-gel films. The emitted light from a light source is guided by a fiber-optic Y-coupler and plastic optical fibers to the pH sol-gel film in a pH sensing probe. The pH change in the sensing probe gives rise to a change in the color of the pH sol-gel film, and the optical characteristic of reflected light through the pH sol-gel film is also changed. Therefore, we have measured the spectra of reflected lights, which are changed according to the color variations of the pH sol-gel films with different pH values, by using of a spectrometer. Also, the relationships between the pH values and the intensities of reflected lights are obtained on the basis of the color variations of the pH sol-gel films.