휠췌어 추진시 근전도 신호의 특성 변화

최화순,Choi, Hwa - Soon 대한물리치료학회 2001 대한물리치료학회지 Vol.13 No.3

The purpose of this study was to investigate the possibility of using surface electromyographic signals as a measure of muscle fatigue during the wheelchair propulsion. Subjects performed wheelchair exercise tests on a motor-driven treadmill with a constant-velocity of 1.25 m/sec. During each test, the raw EMC signals were acquired from the surface electrodes attached on the belly of five muscle groups: biceps brachii, pectoralis major. deltoid, triceps brachii, and trapezius. The median power frequency(MPF), and the root mean square(RMS) amplitude were calculated for each cyclic contraction in order to quantify muscle fatigue. During the wheelchair propulsion, the MPF decreased and the RMS increased in the trapezius and deltoid. However, the decreasing MPF and the increasing RMS also fluctuated severly during dynamic muscle contractions. Therefore, the MPF and RMS values should be estimated with well-designed methods and used with caution to quantify muscle fatigue during wheelchair propulsion.

보안 실행 환경을 위한 소프트웨어 기반의 암호화 패턴 부트스트랩

최화순,이재흥,Choi, Hwa-Soon,Lee, Jae-Heung 한국전기전자학회 2012 전기전자학회논문지 Vol.16 No.4

현재 대부분 시스템은 부트 펌웨어에 대한 보안 취약점이 무시되어 왔다. 부트 펌웨어는 하드웨어 제어 권한과 다른 외부 장치의 권한을 가지고 있기 때문에 보안 메커니즘이 고려되지 않은 상태에서는 악의적인 프로그램이나 코드에 의해 하드웨어가 제어되고 악의적인 코드에 의해 운영체제 손상, 프로그램 도용과 같은 심각한 시스템의 오류를 초래할 가능성이 높다. 본 논문에서는 부트 펌웨어에 대한 신뢰성을 제공하기 위해 악의적인 코드 탐색과 프로그램 도용방지, 운영체제의 보안 로드를 위하여 기존 부트스트랩 방식에 벗어난 암호화된 부트스트랩 패턴을 가지는 소프트웨어 기반의 구조적 보안 메커니즘을 제안한다. 또한 실험 결과를 통해 다른 소프트웨어 보안 메커니즘 비해 적은 1.5~3% 사이의 오버헤드와 검출능력의 우수함을 입증한다. Most current systems have ignored security vulnerability concerned with boot firmware. It is highly likely that boot firmware may cause serious system errors, such as hardware manipulations by malicious programs or code, the operating system corruption caused by malicious code and software piracy under a condition of no consideration of security mechanism because boot firmware has an authority over external devices as well as hardware controls. This paper proposed a structural security mechanism based on software equipped with encrypted bootstrap patterns different from pre-existing bootstrap methods in terms of securely loading an operating system, searching for malicious codes and preventing software piracy so as to provide reliability of boot firmware. Moreover, through experiments, it proved its superiority in detection capability and overhead ranging between 1.5 % ~ 3 % lower than other software security mechanisms.

근전도(EMG) 방식 동력의수의 동작제어 기법

최화순 ( Choi Hwa-soon ) 대구대학교 특수교육재활과학연구소 2000 再活科學硏究 Vol.16 No.1

본 연구는 상지절단 장애인에게 적합한 근전도식 상완의수의 제어방법을 개발하기 위한 것이다. 동력식 상완의수는 손가락 오므리기, 손목회전, 팔꿈치 굽히기 등 3-자유도 동작의 구현이 가능하여야 한다. 이러한 3-자유도 동작을 정확히 구현하고 쉽게 제어할 수 있도록 하기 위하여 근저도 제어방법으로서 대응 제어법, 선택적 제어법, 순차적 제어법, 신경회로망 제어법 등을 제안하였고 그 적용결과를 모의실험을 통하여 비교 평가하였다. 이러한 제어방법 들은 각각의 장단점을 지니고 있어, 의수사용자의 상태에 따라 적절한 제어법의 선택이 필요하다. The main objective of this study is to develop a control methodology adequate for the myoelectric arm for the above elbow amputee. The above elbow amputee may need an artificial arm which has three degree of freedom of motion such as finger grasping, wrist rotation. and elbow flexion. Because the usefulness of prosthetic arm strongly depends on the easiness of control and accuracy of the resulting motions, various myoelectric control algorithms such as the one to one matching algorithm. the site selection algorithm, the sequent input algorithm, the neural network method were proposed and tested under the simulated condition by attaching the EMG sensors on the normal human subjects. Test results showed that each method had its own merits and disadvantages. thus the choice of control methods should be determined according to the user``s conditions and requirements.

경사진 안창이 보행시 하지관절에 미치는 영향

권민정,최화순,정민근,나석희,Kwon, Min-Jeong,Choi, Hwa-Soon,Chung, Min-K.,Na, Seok-Hee 대한인간공학회 2007 大韓人間工學會誌 Vol.26 No.1

Despite the widespread use of laterally wedged insoles for patients with knee osteoarthritis and medially wedged insoles for controlling rearfoot pronation, an understanding of the effects of wedged insoles was limited and sometimes controversial. The objective of this study was to evaluate the effect of wedged insoles on the kinematics and kinetics of normal gait. Ten male subjects without history of lower limb disorders were recruited. Each subject performed four gait cycles under each of seven conditions; shod with 5$^{\circ}$, 8$^{\circ}$ and 15$^{\circ}$, 8$^{\circ}$ and 15$^{\circ}$ laterally wedged insoles. In order to determine statistical differences among seven conditions, the measured temporal spatial variables, angular displacements, joint moments, and ground reaction forces were compared with a one-way analysis of variance. Some significant changes induced by wedged insoles were apparent in joint moments and ground reaction forces. The medially wedged insole increased the laterally directed ground reaction force and varus moments at the ankle force and varus moments at the ankle and the knee.

국내 치과의사의 근골격계질환 실태 조사

차주형,유태범,최화순,이재봉,김명기,정민근,정철현,Cha, Joo-Hyoung,Ryu, Tae-Beum,Choi, Hwa-Soon,Lee, Jai-Bong,Kim, Myeng-Ki,Chung, Min-K.,Jeong, Cheol-Hyun 대한인간공학회 2007 大韓人間工學會誌 Vol.26 No.2

Dentists are known to be highly exposed to the musculoskeletal disorders (MSD). The present study investigated the prevalence of MSD among Korean dentists and association between their MSD and physical workload. In addition, work-related causes of high physical workload were identified and needs of dentists were collected for improvement of dental instrument and environment. Four types of questionnaires including the Nordic questionnaire were used to investigate body troubles, physical workload, causes of physical workload, and improvement priority of dental components. A total of 104 dentists in Seoul were participated in the survey. Neck trouble (82%) was the most prevalent in the participated dentists and shoulder (68%) and low back trouble (56%) followed, while low back trouble was reported to be most common in previous western studies. The body troubles were related to the physical workload of the corresponding body parts, although they were not associated with personal characteristics. Most dentists selected 'to keep direct view inside patient's mouth' and 'no support of the hand with dental instruments' as causes of awkward and strenuous work postures. They wanted design improvement for some components in their operating room such as operating light and arrangement of workplace.

보행주기에 따른 맞춤형 단하지보조기의 응력분포 특성

최영철(Young Chul Choi),이근민(Kun Min Rhee),최화순(Hwa Soon Choi) Korean Society for Precision Engineering 2008 한국정밀공학회지 Vol.25 No.3

An ankle-foot orthosis(AFO) is a brace for persons with gait disabilities to support or replace the function of ankle joint. Ankle-foot orthoses(AFO's) are usually prescribed to alleviate the drop-foot by constraining the excessive plantar flexion. The shape and the strength of the AFO are often based on 'trial and error' due to a lack of knowledge of the stress distribution in the AFO. In this study, an improved stress-freezing method was proposed to measure the stress distribution characteristics in the AFO. As a result, a photoelastic material with low freezing temperature was developed to measure the stresses under a person's direct contact loading condition. The three-dimensional stress-frozen photoelastic models of AFO's for five stages of stance phase such as heel contact, foot flat, mid stance, heel off, and toe off were produced. The results of photoelastic analysis revealed that the stresses developed in the AFO were varied considerably from tensile to compressive or vice versa, during walking. At the posterior part of ankle joint in the AFO, the maximum compressive stress of 1.81㎫ was observed in the mid stance, and the maximum tensile stress of 0.74㎫ was observed during heel contact. The overall stress levels in the AFO's were low in the toe off phase, The results suggested that the posterior part of ankle joint might be the most fragile part in the AFO.

수ㆍ전동 복합기능의 접이식 휠체어 개발

최영철(Young Chul Choi),이근민(Kun Min Rhee),최화순(Hwa Soon Choi),서영택(Young Taek Seo) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.2

Although there existed many types of manual/power hybrid wheelchairs, their use was not widespread because of their inconvenience in converting drive system and in folding frames. To canγ a wheelchair in the car or to convert driving methods, some hard work of disassembling or exchanging wheels was required for most of currently available hybrid wheelchairs. In this study, the standard foldable manual wheelchair was reformed to a power wheelchair by installing the newly developed Axial Flux Permanent Magnet(AFPM) type of brushless direct current(BLDC) motor on each rear hub of wheelchair. This wheelchair could be driven by manual or electric power without exchanging wheels, thus no additional work was needed for carriage or for power conversion. The developed wheelchair was evaluated for durability, stability, maneuverability, cost, and reliability in accordance with the Korean standards. The results indicated that the developed hybrid wheelchair was good enough for commercialization comparing to other imported wheelchairs.

한국 성인의 정상 보행데이터를 이용한 보행진단 지원 시스템의 개발

김동진(Dongjin Kim),유태범(Taebeum Ryu),권세만(Seman Kwon),최화순(Hwa Soon Choi),정민근(Min K. Chung) 대한산업공학회 2007 대한산업공학회지 Vol.33 No.4

발 뒤축 내·외측 경사진 안창이 족부압력에 미치는 영향

유태범(Taebeum Ryu),채병기(Byungkee Chae),임완수(Wansoo Lim),최화순(Hwa Soon Choi),정민근(Min K. Chung) 대한산업공학회 2008 대한산업공학회지 Vol.34 No.1