기능적 전기자극을 이용한 하반신마비 장애인의 독립 보행

강곤(Gon Khang) Korean Society for Precision Engineering 2002 한국정밀공학회지 Vol.19 No.4

맞춤형 생활환경 설계 및 제어 시스템

강곤(Gon Khang) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.2

근육의 에너지 소모와 기능적 전기자극 시스템의 제어기 설계에의 응용

강곤 건국대학교 의과학연구소 1993 건국의과학학술지 Vol.3 No.-

I have formulated the rate of energy liberated by muscles in order to design an energy-minimizing control law for paraplegic standing induced by functional electrical stimulation. The reason is that electrical stimulation causes muscles to fatigue much faster than voluntary contraction and energy minimization is assumed to delay muscle fatigue. The computer model I used for the control-system design consists of pulse train activation dynamics, contraction dynamics, body-segmental dynamics and an output feedback control law. Linearization enabled me to compute a constant feedback-gain matrix. The feedback controller computes joint-torque-actuator activations and distributes them into individual muscles based on energy minimization. The simulation results indicate that the current output-feedback control law functions well so that the body can recover and maintain upright posture from up to 40。 of initial perturbations in the segmental orientations.

기능적 전기자극에 의한 하반신 마비환자의 보행에서의 다리관절 각도 분석

강곤,송동진 건국대학교 의과학연구소 1999 건국의과학학술지 Vol.8 No.-

This research was designed to measure and investigate the sagittal plane angles of the lower extremity joints during functional electrical stimulation(FES) walking and normal walking. The purpose of this research is to get insights into appropriate stimulation patterns based on the sagittal plane angles. The subject is a paraplegic male with incomplete lesion at T12. We strengthened his leg muscles via FES excise. And then he started FES standing and walking. The three stimulation combinations we applied to induce FES walking are as following : two knee extensors, two knee extensors and the peroneal nerve(PN), and three knee extensors and PN. We have developed a goniometer system in order to measure sagittal planed angles of the leg joints during walking. The stance phase of FES walking was significantly longer than that of normal walking. It depended on the stimulation combinations which angle shows the largest amplitude, whereas the amplitude of knee angle was the largest during normal walking. The angle of the hip joint in FES walking decreased initially and then increased immediately before the swing phase. The knee angle remained 0 during the stance phase of FES walking on the contrary to normal walking. This is because the knee extensors are stimulated throughout the stance phase in order to support the body weight. Although the ankle angle in normal walking increase during the swing phase, the FES walking shows that the ankle angle slightly decreases during the swing phase since he cannot use the ankle flexors. As the knee extensors fatigue, the paraplegic subjects could not maintain the knee angle at 0 during the stance phase and the amplitude of the ankle angle increased.

근육의 힘이 신체 각 부분의 가속도에 미치는 영향

강곤,Khang, Gon 대한기계학회 1991 대한기계학회논문집 Vol.15 No.6

본 연구에서는 근육수축에 의해 발생되는 각 신체부분의 각가속도의 방향이 다음 두가지 요소의 변화에 따라 어떻게 달라지는가를 중점적으로 살펴보기로 한다` (1) 신체매개변수(body-segmental parameter): 길이, 무게 등, (2) 신체 각 부분의 위치. 이러한 상관관계를 더욱 명확히 이해함으로써, 주어진 운동(given task)을 FES 에 의해 수행하고자 할 때 전기적으로 자극되어야 할 근육을 사전에 선택할 수 있을 것이다. When the functional electrical stimulation is employed to recover mobility to the plegic, it is very important to understand functions of the selected muscles. I have investigated how a muscle acts to accelerate the body segments, since the body segements are connected by joints so that contraction of a muscle not only rotates the segments to which it is attached but also causes other segments to rotate by creation a reaction force at every joint, which is called the inertial coupling. I found that a single-joint muscle always acts to accelerate the spanned joint in the same direction as the joint torque produced by the muscle. However, a double-joint muscle can act to accelerate the spanned joint in the opposite direction to the joint torque produced by the muscle depending on (1) the body position, (2) the body-segmental parameters, and (3) the type of the movement. Investigating the condition number of the inertia matrix of the body-segmental model gave us some insights into how controllable the body-segmental system is for different values of the factors mentioned above. The results suggested that the upright position is the most undesirable position to independently control the three segments(trunk, thigh and shank) and that the controllability is the most sensitive to variation of the shank length and the trunk mass, which implies that accuracy is required particularly when we estimate these two body-segmental parameters before the paralyzed muscles are innervated by using electrical stimulation.

FNS를 사용한 하반신마비자의 일어서기

강곤,Khang, Gon 대한의용생체공학회 1990 의공학회지 Vol.11 No.1

Functional neuromuscular stimulation(FNS)를 사용하여 하반선마비사가 앉은 상태에서부터 일어나 균형을 유지할 수 있도록 하기 위하여 FNS의 자동제어 시스댐을 개발하였다. Output feedback gain matrix를 최적제어이론을 사용하여 계산하기 위하여 비선형 선체모델을 직립위치에 대하여 선형화하였다. 제어기는 측정된 output에 의하여 매순간 각 선체조인트에 필요한 torque할 계산 하며, 이 조인트 torque는 근육이 최소한의 에너지를 사용하게끔 각 단육에 배분된다. 컴퓨터 시뮬레이션결과, 이 제어 시스템을 사용하여 각 조인트가 약 45도 정도 구부버진 상태에서 부터 직립위치를 회복할 수 있으며 팔의 움직임으로 대표되는 외부로부터의 방해를 반았블 때에도 직립 위치를 자동적으로 유지할 수 있었다. An implementation scheme of the magnetic nerve stimulator using a switching mode power supply is proposed. By using a switching mode power supply rather than a conventional linear power supply for charging high voltage capacitors, the weight and size of the magnetic nerve stimulator can be considerably reduced. Maximum output voltage of the developed magnetic nerve stimulator using the switching mode power supply is 3,000 volts and switching time is about 100 msec. Experimental results or human nerve stimulations using the developed stimulator are presented.

The effect of fixation plate use on bone healing during the reconstruction of mandibular defects

Hong, Khang Do Gia,Kim, Seong-Gon,Park, Young-Wook The Korean Association of Oral and Maxillofacial S 2019 대한구강악안면외과학회지 Vol.45 No.5

Objectives: This study sought to compare efficiency results between the use of a customized implant (CI) and a reconstruction plate (RP) in mandibular defect reconstruction in an animal model. Materials and Methods: Fifteen rabbits underwent surgery to create a defect in the right side of the mandible and were randomly divided into two groups. For reconstruction of the mandibular defect, the RP group (n=5) received five-hole mini-plates without bone grafting and the CI group (n=10) received fabricated CIs based on the cone-beam computed tomography (CBCT) data taken preoperatively. The CI group was further divided into two subgroups depending on the time of CBCT performance preoperatively, as follows: a six-week CI (6WCI) group (n=5) and a one-week CI (1WCI) group (n=5). Daily food intake amount (DFIA) was measured to assess the recovery rate. Radiographic images were acquired to evaluate screw quantity. CBCT and histological examination were performed in the CI subgroup after sacrifice. Results: The 1WCI group showed the highest value in peak average recovery rate and the fastest average recovery rate. In terms of reaching a 50% recovery rate, the 1WCI group required the least number of days as compared with the other groups ($2.6{\pm}1.3days$), while the RP group required the least number of days to reach an 80% recovery rate ($7.8{\pm}2.2days$). The 1WCI group showed the highest percentage of intact screws (94.3%). New bone formation was observed in the CI group during histological examination. Conclusion: Rabbits with mandibular defects treated with CI showed higher and faster recovery rates and more favorable screw status as compared with those treated with a five-hole mini-plate without bone graft.

Computer Simulation of a Hydraulic Control System

강곤,이교일,Khang, Gon,Lee, Kyo-Il The Korean Society of Mechanical Engineers 1982 대한기계학회논문집 Vol.6 No.2

이 논문에서는 유압제어장치의 응답에 대하여 관성하중, 점성하중, 쿨룸(Coulomb)마찰 및 입력 신호의 주파수가 시스템에 미치는 영향을 고찰하였고, 이에 따른 속도와 압력파형을 주로 서 술하였다. 피스톤의 드리프트(drift)와 스프링하중을 제외한 대부분의 요소가 고려되었다. 추출된 방정식은 모두 무차원화 하였으며 입력 신호를 계단함수로 할 때에는 위치 피이드백 (feedback)이 삽입되었다.

Effects of Stimulation Conditions and Waveforms on Muscle Contractile Characteristics

Song Tongjin,Khang Gon The Korean Society of Medical and Biological Engin 2005 의공학회지 Vol.26 No.2

This study was designed to apply the stimulation system developed in our laboratory to investigate how the stimulation conditions affect the muscle contractile characteristics in the isometric condition as well as during the FES standing/walking. Four paraplegic and ten healthy subjects participated in this study, and their knee extensors were voluntary contracted or electrically stimulated to measure the muscle force and the fatigue index for different waveforms of the pulse train. We also investigated different combinations of the electrode positions during standing/walking. It was confirmed that continuous and high-frequency stimulation causes faster fatigue than intermittent and low-frequency stimulation. Fatigue resistance was higher around the optimal muscle length than at a stretched position in healthy subjects, whereas the opposite was observed in paralyzed subjects. The paired t-test results with the level of significance at 0.01 indicated that the sinusoidal waveform generated the largest torque among the four typical waveforms. Although statistically not very significant, the sinusoidal waveform also generated, in general, the highest fatigue resistance at an intensity level below the supramaximal stimulation. One of the paraplegic subject who participated in the standing/walking program can now stand up for 1 minute and 50 seconds with the knee extensors, and walk for about 5 minutes at the speed of 12m/sec.

The Elastic Moduli and Fatigue Properties of Canine Trabecular Bone Tissue

Kui Won Choi,Gon Khang,Steven A. Goldstein 대한기계학회 2001 KSME International Journal Vol.15 No.7