학제간 통합연구를 향한 운동역학 : 신발테스트용 로봇에 관한 연구

탁계래 ( Gye Rae Tack ),( Gerald Cole ),( Benno Nigg ) 한국운동역학회 2005 한국운동역학회 춘계학술발표논문집 Vol.2005 No.-

척추성형술을 위한 의료 영상 시스템의 설계 및 개발

탁계래,이상범,이성재,Tack, Gye-Rae,Lee, Sang-Bum,Lee, Sung-Jae 한국정보처리학회 2003 정보처리학회논문지B Vol.10 No.5

척추에 대한 외과수술은 신경조직을 손상하지 않아야 하기 때문에 수술 절차가 신중하게 계획되고 고도의 정밀을 요구한다. 척추성형술(verte-broplasty)은 골다공증으로 인한 척추의 골절을 치료하기 위해 제안된 비교적 새로운 외과적인 수술방법으로 최소침습적인 수술 기법으로 피부를 통하여 골절된 척추부위에 구멍을 내고 그곳에 PMMA(polymethylmethacrylate)라 불리는 골시멘트(bone cement)를 주입하여 치료하는 방법이다. 최근의 연구결과, 수술 후 즉각적인 고통의 경감을 가져오며, 골다공증으로 인한 골절부위에 강도가 강한 골시멘트를 주입하게 됨으로써 골다공증 척추체에 구조적인 안정성을 제공해 주는 것으로 알려져 있다. 수술 후 발생하는 합병증의 대부분은 과도한 골시멘트의 주입으로 인한 것으로 알려져 있으며, 따라서 척추성형술의 치료에 가장 중요한 요인은 주입한 골시멘트의 양을 조절하는 것이다. 이에 본 연구에서는 환자의 컴퓨터단층촬영(computer tomography)을 통하여 획득한 영상을 토대로 척추성형술 시술시 필요한 의료 영상 시스템을 설계 및 개발하고, 텍스처 분석을 통하여 개개인의 환자에게 필요한 골시멘트의 양을 계산하는 알고리즘을 개발하여 이를 실제 환자의 시술시에 적용해 보았다. 결과적으로 본 시스템은 척추성형술시에 최적의 골시멘트의 양을 예측할 수 있었으며, 정형외과의 다른 부위의 수술시에도 적용가능성을 확인할 수 있었다. Since surgical treatment of the spine should overcome neurological compromises, the operative procedures need to be carefully planned and carried out with high degree of precision. Percutaneous vertebroplasty is a surgical procedure that was introduced for the treatment of compression fracture of the vertebrae. This procedure includes puncturing vertebrae and filling with polymethylmethacrylate (PMMA). Recent studies have shown that the procedure could provide structural reinforcement for the osteoporotic vertebrae while being minimally invasive and safe with immediate relief of pain. However, failures of treatment due to excessive PMMA volume injection have been reported as one of complications in vertebroplasty. It is believed that the control of PMMA volume is one of the most critical factors that can reduce the incidence of complications. Therefore, clinical success of vertebroplasty can be dependent on the volume of PMMA injection for a given patient. In this study, the optimal volume of PMMA injection for vertebroplasty was predicted based on the image analysis of a given patient.

유한 요소 해석을 이용한 고주파 간 종양 절제술의 입력 파형 최적화를 위한 연구

임도형,남궁범석,이태우,최진승,탁계래,김한성,Lim, Do-Hyung,NamGung, Bum-Seok,Lee, Tae-Woo,Choi, Jin-Seung,Tack, Gye-Rae,Kim, Han-Sung 대한의용생체공학회 2007 의공학회지 Vol.28 No.2

Hepatocellular carcinoma is significant worldwide public health problem with an estimated annually mortality of 1,000,000 people. Radiofrequency (RF) ablation is an interventional technique that in recent years has come to be used for treatment of the hepatocellualr carcinoma, by destructing tumor tissues in high temperatures. Numerous studies have been attempted to prove excellence of RF ablation and to improve its efficiency by various methods. However, the attempts are sometimes paradox to advantages of a minimum invasive characteristic and an operative simplicity in RF ablation. The aim of the current study is, therefore, to suggest an improved RF ablation technique by identifying an optimum RF pattern, which is one of important factors capable of controlling the extent of high temperature region in lossless of the advantages of RF ablation. Three-dimensional finite element (FE) model was developed and validated comparing with the results reported by literature. Four representative Rf patterns (sine, square, exponential, and simulated RF waves), which were corresponding to currents fed during simulated RF ablation, were investigated. Following parameters for each RF pattern were analyzed to identify which is the most optimum in eliminating effectively tumor tissues. 1) maximum temperature, 2) a degree of alteration of maximum temperature in a constant time range (30-40 second), 3) a domain of temperature over $47^{\circ}C$ isothermal temperature (IT), and 4) a domain inducing over 63% cell damage. Here, heat transfer characteristics within the tissues were determined by Bioheat Governing Equation. Developed FE model showed 90-95% accuracy approximately in prediction of maximum temperature and domain of interests achieved during RF ablation. Maximum temperatures for sine, square, exponential, and simulated RF waves were $69.0^{\circ}C,\;66.9^{\circ}C,\;65.4^{\circ}C,\;and\;51.8^{\circ}C$, respectively. While the maximum temperatures were decreased in the constant time range, average time intervals for sine, square, exponential, and simulated RE waves were $0.49{\pm}0.14,\;1.00{\pm}0.00,\;1.65{\pm}0.02,\;and\;1.66{\pm}0.02$ seconds, respectively. Average magnitudes of the decreased maximum temperatures in the time range were $0.45{\pm}0.15^{\circ}C$ for sine wave, $1.93{\pm}0.02^{\circ}C$ for square wave, $2.94{\pm}0.05^{\circ}C$ for exponential wave, and $1.53{\pm}0.06^{\circ}C$ for simulated RF wave. Volumes of temperature domain over $47^{\circ}C$ IT for sine, square, exponential, and simulated RF waves were 1480mm3, 1440mm3, 1380mm3, and 395mm3, respectively. Volumes inducing over 63% cell damage for sine, square, exponential, and simulated RF waves were 114mm3, 62mm3, 17mm3, and 0mm3, respectively. These results support that applying sine wave during RF ablation may be generally the most optimum in destructing effectively tumor tissues, compared with other RF patterns.

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.

심리ㆍ생리 평가를 기반으로 한 통합 감성평가 시스템

정순철(Soon-Cheol Chung),탁계래(Gye-Rae Tack),이정한(Jeong-Han Yi),민병찬(Byung-Chan Min) 대한산업공학회 2005 대한산업공학회지 Vol.31 No.2

다양한 보행속도와 경사각에 대한 보행수 검출을 위한 필터링 조건과 역치의 결정

권유리,김지원,이재호,탁계래,엄광문,Kwon, Yu-Ri,Kim, Ji-Won,Lee, Jae-Ho,Tack, Gye-Rae,Eom, Gwang-Moon 대한의용생체공학회 2009 의공학회지 Vol.30 No.6

The purpose of this study is to determine optimal filtering condition and threshold for the detection of gait-cycles for various walkway slopes as well as gait velocities. Ten young healthy subjects with accelerometer system on thigh and ankle walked on a treadmill at 9 conditions (three speeds and three slopes) for 5 minutes. Two direction signals, i.e. anterior-posterior (AP) and superior-inferior (SI) directions, of each sensor (four sensor orientations) were used to detect specific events of gait cycle. Variation of the threshold (from -1G to 1G) and lowpass cutoff frequency (fc) were applied to the event detection and their performance was evaluated according to the error index (EI), which was defined as the combination of the accuracy and false positive rate. Optimal fc and threshold were determined for each slope in terms of the EI. The optimal fc, threshold and their corresponding EI depended much on the walkway slope so that their coefficients of variation (CV) ranged 19~120%. When all data for 3 slopes were used in the identification of optimal conditions for each sensor, the best error indices for all sensor orientations were comparable ranging 1.43~1.76%, but the optimal fc and threshold depended much on the sensor position. The result indicates that the gait-cycle detection robust to walkway slope is possible by threshold method with well-defined filtering condition and threshold.

보행속도변화에 따른 인지 과제 수행이 보행수 변동성에 미치는 영향

최진승,유지혜,김형식,정순철,이정한,이봉수,탁계래,Choi, Jin-Seung,Yoo, Ji-Hye,Kim, Hyung-Shik,Chung, Soon-Cheol,Yi, Jeong-Han,Lee, Bong-Soo,Tack, Gye-Rae 대한의용생체공학회 2006 의공학회지 Vol.27 No.6

The purpose of this study was to investigate the effect of performing a cognitive task during treadmill walking on the stride rate variability. Ten university students(age $24.0{\pm}0.25$, height $172{\pm}3.1cm$, weight $66{\pm}5.3kg$) were participated in dual task experiments which consist of both walking alone and walking with a cognitive task. Two-back task was selected for the cognitive task since it did not have learning effect during the experimental procedure.3D motion analysis system was used to measure subject's position data by changing walking speed with 4.8, 5.6, 6.4, 6.8, and 7.2 km/hr. Stride rate was calculated by the time between heel contact and heel contact. Accuracy rate of a cognitive task during walking, coefficient of variance, allometric scaling methods and Fano factor were used to estimated the stride rate variability. As the walking speed increased, accuracy rate decreased and the logarithmic value of Fano factor increased which showed the statistical difference. Thus it can be concluded that the gait control mechanism is distracted by the secondary attention focus which is the cognitive task ie. two-back task. Further study is needed to clarify this by increasing the number of subject and experiment time.

치료용 고에너지 전자선 계측을 위한 광섬유 방사선 센서의 제작 및 특성 분석

장경원,조동현,유욱재,이봉수,이정한,탁계래,조효성,김신,Jang, Kyoung-Won,Cho, Dong-Hyun,Yoo, Wook-Jae,Lee, Bong-Soo,Yi, Jeong-Han,Tack, Gye-Rae,Cho, Hyo-Sung,Kim, Sin 대한의용생체공학회 2006 의공학회지 Vol.27 No.6

In this study, we have fabricated a fiber-optic radiation sensor using an organic scintillator for high energy electron beam therapy. The intensities of scintillating light from a fiber-optic radiation sensor are measured with different field size, electron beam energy and monitor unit of a clinical linear accelerator. To obtain percent depth dose(PDD), the amount of scintillating light is measured at different depth of polymethylmethacrylate(PMMA) phantom. Also the intensity of Cerenkov light is measured and characterized as a function of incident angle of electron beam and a subtraction method is investigated using a background optical fiber to remove a Cerenkov light.

개인의 선호보행속도에 대한 기초연구

최진승(Jin Seung Choi),강동원(Dong Won Kang),탁계래(Gye Rae Tack) 한국사회체육학회 2011 한국사회체육학회지 Vol.0 No.45

The purpose of this study was to investigate determinants of preferred walking speed(PWS) by comparing three methods for measuring PWS. Two measured PWSs by treadmill walking and calculated PWS by Froud velocity(VF) using lower limb length were compared in this experiment. In the results, there was no difference between two measured PWSs, while there was difference between calculated PWS by VF and others. To identify discrepancy, physical characteristics(height, weight, lower limb length, joint range of motion(ROM), joint torque) and personality by JAS questionaire were measured and compared. There were significant differences at lower limb length (r=.695, p=.024), hip joint ROM (r=-.653, p=.026), ankle joint plantar-flexion torque (r=.702, p=.041). PWS of type A personality were faster than that of type B personality(t=-2.537, p=.024). These results may be helpful to clarify various factors for determined PWS and understand the meaning of determined PWS.

트레드밀을 이용한 보행간 Variability 분석에 관한 연구

최진승 ( Jin Seung Choi ),강동원 ( Dong Won Kang ),탁계래 ( Gye Rae Tack ) 한국운동역학회 2007 한국운동역학회지 Vol.17 No.4