범용 매스터 암을 이용한 원격 조작 시스템의 개발

차동혁(Dong Hyuk Cha),조형석(Hyung Suck Cho) 대한전자공학회 1992 대한전자공학회 학술대회 Vol.1992 No.10

In this paper, an unilateral teleoperation system using an universal master arm is developed. This system is composed of an universal master arm, a slave arm and a telerobot controller. The universal master arm has a vertically articulated type link structure, while an industrial robot is used as a slave arm. As the shapes of master arm and slave arm are different, the workspace mapping is needed, which maps the workspace of master arm to that of slave arm. Experimental results show that the slave arm of the developed system effectively follows the operator's motion.

중학생의 건강에 대한 부모 및 지역사회 안전도 효과

차동혁 ( Dong Hyuk Cha ),옥선화 ( Sun Wha Ok ) 대한가정학회 2014 Human Ecology Research(HER) Vol.52 No.5

Focusing on the holistic concept of health, which embraces both physical and mental health, we investigated the effects of parenting and community factors on the health of 1,248 first- and second-year middle school students, on the basis of the data of the Korean Survey on the Activities and Culture of Youth and Children in 2009. The latent class analysis revealed three types of holistic health groups from the data, named as follows: (1) the healthy group, (2) moderate group, and, (3) fragile group. Then, we analyzed the effects of parenting factors and community safety on these health types according to the students` year in school and their mother`s status of employment. The results showed that the first-year students had consistent parenting effects on their own type of health, while the safety of the community only partly contributed to the probability of affiliation to healthier types. However, in the case of the second-year students, a neglectful parenting style and community safety consistently had significant effects on the students` type of health, while parental concern about an adolescent`s health did not contribute to the probability of affiliation to healthier types when only the mother was unemployed. The discussion considers how these results provide basic resources for formulating policies and creating intervention programs for addressing the health problems of adolescents.

신경 회로망을 이용한 원격조작 로보트의 컴플라이언스 제어

차동혁(Dong-Hyuk Cha),박영수(Young-Soo Park),조형석(Hyung-Suck Cho) 제어로봇시스템학회 1991 제어로봇시스템학회 국내학술대회 논문집 Vol.1 No.1

청소년의 여가문화활동이 자기조절능력, 학업성취도 및 자아존중감에 미치는 영향: 부의 학력에 따른 차이를 중심으로

차동혁 ( Cha Donghyuk ),옥선화 ( Ok Sun Wha ) 한국보건사회연구원 2014 保健社會硏究 Vol.34 No.1

주5일 근무제의 전면 시행 및 여가문화의 확산과 함께 청소년의 여가문화활동의 중요 성이 제기되면서 이에 대한 지원이 가족뿐만 아니라 학교와 지역사회, 정부의 정책 단위 에서도 이루어지고 있다. 본 연구에서는 이러한 청소년의 여가문화활동이 청소년의 교양을 함양하고 균형 있는 성장을 도모할 것을 목적으로 하는 문화자본으로 인식하고, 여가문화활동이 실제로 청소년의 균형 있는 성장에 영향을 미치는지를 살펴보고자 하였다. 이를 위하여 본 연구에서는 한국청소년정책연구원이 2012년에 실시한 3차 한국아 동·청소년패널조사 자료 중 중학교 3학년 1,673명을 대상으로, 여가문화활동이 자기 조절능력과 학업성취도, 자아존중감에 영향을 미치는 구조적 관계를 분석하였고, 이 관 계가 부의 학력에 따라 차이를 보이는지 확인하였다. 그 결과, 청소년의 여가문화활동은 자기조절능력과 학업성취도, 자아존중감에 모두 유의한 정적 직접효과를 가졌으며, 자기조절능력을 매개로 학업성취도와 자아존중감에 미치는 정적인 간접효과도 유의하였다. 이러한 청소년 여가문화활동의 영향력에 대한 부의 학력의 조절효과는 유의미하지 않았다. 이는 부모의 문화자본에 관계 없이 청소년의 여가문화활동이 체화된 문화자본으로 기능하여 청소년의 학업 성취와 자아존중감에 미치는 영향력이 유지된다는 의미이며, 청소년의 균형 있는 성장을 위하여 사회 계층에 관계없이 청소년이 여가문화활동에 참여할 수 있도록 적극 지원해주어야 함을 시사한다. Along with the enforcement of the five-day work week, adolescents` leisure and cultural activities have been recognized so important that families, schools, local communities, and the government are trying to provide support for these activities. In this research, we regarded adolescents` leisure and cultural activities as a kind of embodied cultural capital which have the intention to educate them as a person of culture with balanced human development. With this regard, we examined whether or not adolescents` leisure and cultural activities had an effect on their balanced growth. We chose 1,673 middle school seniors from the third wave of Korea Children and Youth Panel Survey conducted in 2012 by National Youth Policy Institute. Then, we analyzed the effects of adolescents` leisure and cultural activities as embodied cultural capital on their self-regulation, academic achievements, and self-esteem. The results showed that adolescents` leisure and cultural activities had not merely significant positive direct effects on all the three latent variables but significant positive indirect effects on the academic achievements and the self-esteem mediated by the self-regulation. The fathers` educational level did not moderate these influences of adolescents` leisure and cultural activities. This means that these influences can be maintained equally, irrespective of parents` cultural capital. It also suggests that families, schools, local communities, and the government all should highly encourage adolescents to participate leisure and cultural activities regardless of their social classes.

범용 매스터 암을 이용한 원격 조작 시스템의 개발

차동혁(Dong Hyuk Cha),조형석(Hyung Suck Cho) 제어로봇시스템학회 1992 제어로봇시스템학회 국내학술대회 논문집 Vol.1 No.1

증례 : 대망에 발생한 IgG4 연관 염증성 가성종양 1예

차동혁 ( Dong Hyuk Cha ),최철웅 ( Cheol Woong Choi ),김산 ( San Kim ),박태익 ( Tae Ik Park ),조우성 ( Woo Sung Jo ),김형욱 ( Hyung Wook Kim ),강대환 ( Dae Hwan Kang ) 대한내과학회 2013 대한내과학회지 Vol.84 No.3

자동조정 퍼지룰을 이용한 슬레이브 암의 시각서보

김주곤,차동혁,김승호,Kim, Ju-Gon,Cha, Dong-Hyeok,Kim, Seung-Ho 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.10

In telerobot systems, visual servoing of a task object for a slave arm with an eye-in-hand has drawn an interesting attention. As such a task ingenerally conducted in an unstructured environment, it is very difficult to define the inverse feature Jacobian matrix. To overcome this difficulty, this paper proposes an auto-tuning fuzzy rule-based visual servo algorithm. In this algorithm, a visual servo controller composed of fuzzy rules, receives feature errors as inputs and generates the change of have position as outputs. The fuzzy rules are tuned by using steepest gradient method of the cost function, which is defined as a quadratic function of feature errors. Since the fuzzy rules are tuned automatically, this method can be applied to the visual servoing of a slave arm in real time. The effctiveness of the proposed algorithm is verified through a series of simulations and experiments. The results show that through the learning procedure, the slave arm and track object in real time with reasonable accuracy.

개방성 종골 골절의 수술적 치료 결과

김바롬,이준영,차동혁,Kim, Ba Rom,Lee, Jun Young,Cha, Donghyuk 대한족부족관절학회 2021 대한족부족관절학회지 Vol.25 No.3

Purpose: This paper reports the surgical treatment results of open calcaneal fractures performed at the author's clinics focusing on open calcaneal fractures to help understand the appropriate treatment and realistic outcomes. Materials and Methods: This study was conducted on 22 cases out of 30 patients who visited the hospital from February 2009 to December 2019 and were followed up for more than one year. In open fractures, the fracture was classified using the Gustilo-Anderson classification and was evaluated using the soft tissue status at the time of visit. Intra-articular calcaneal fractures were classified using Sanders classification. The radiological parameters were measured for the Böhler angle, Gissane angle, calcaneal length, height, and width before and after surgery, and at the last follow-up. The clinical outcomes were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scale and investigated complications. In addition, statistical analysis of the incidence and associated factors of posttraumatic arthritis was conducted. Results: In all cases, the surgical treatment was performed by minimally invasive surgery. The AOFAS ankle-hindfoot scale conducted for a clinical evaluation of the final follow-up was averaged 72.5 points. In the classification of open fractures, the Gustilo-Anderson classification type IIIA was the most common, and the Sanders type III was the most common. Of the 22 cases after surgery, 15 cases had complications, 11 cases had posttraumatic arthritis, eight cases had an infection, and 4 cases had both complications. Only the Sanders classification showed a statistically significant correlation with the incidence of posttraumatic osteoarthritis (p-value 0.032). Conclusion: In treating open calcaneal fractures, internal fixation by a minimally invasive approach showed relatively satisfactory results. However, follow-up research will be needed, including the results of a long-term follow-up through a large number of cases and comparative studies with other surgical methods.

베어 칩 실장 헤드 메커니즘 설계 및 힘 제어 기술개발

심재홍(Jaehong Shim),차동혁(Donghyuk Cha) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

This paper presents a macro/micro flip chip mounting head system for precise force control. In the proposed macro/micro system, the macro actuator is conventional de servo motor with a ball screw mechanism and the micro actuator is a voice coil motor(VCM) that consists of four NdFeB magnets and a winded moving coil. For force control, a sensitive strain-gauge force sensor is mounted in the micro actuator. Through harmonic motion between macro and micro actuator, we would like to get precise contact force control when small sized flip chip is mounted on flexible substrate in high speed. In order to show the effectiveness of the proposed macro/micro flip chip mounting head system, we compared the proposed surface mounting head with the chip mounting head that is equipped with only macro actuator. Various experiments are executed in the mounting condition of various access velocity using hybrid position and force control.

슬관절 전치환술 후 발생한 대퇴골 삽입물 주위 골절의 이중 금속판 고정술

김동휘(Dong Hwi Kim),차동혁(Dong Hyuk Cha),고강열(Kang Yeol Ko) 대한정형외과학회 2021 대한정형외과학회지 Vol.56 No.1

목적: 슬관절 전치환술 후 발생한 대퇴 삽입물 주위 골절에 이중 금속판을 이용한 고정술 후 결과를 평가하고자 한다. 대상 및 방법: 2007년 10월부터 2013년 2월까지 슬관절 전치환술 후 발생한 대퇴골 삽입물 주위 골절 23예 중 Lewis와 Rorabeck의 분류상 II형으로 삽입물 이완은 없으나 과상부 분쇄골절이거나 골절선이 외상과까지 연장됐거나 주대(stem)가 있어 편측 고정만으로 골절부의 안정성을 얻을 수 없다고 판단한 경우에 내, 외측 이중 금속판을 이용하여 내고정술을 시행하고 최소 1년 이상 추시가 가능했던 13예를 대상으로 하였다. 환자의 평균 연령은 72세(65–82세)였고 여자가 11예, 남자가 2예였다. 수상 기전은 낙상이 9예, 교통사고가 4예였다. 류마티스관절염 1예를 제외하고 12예에서 골관절염으로 슬관절 전치환술을 받았고 3예에서 재치환술 등의 이유로 주대가 있었다. 슬관절 전치환술 후 골절 발생까지의 평균 기간은 28개월(1–108개월)이었고, 술 전 환자의 평균 골밀도는 T score -3.2 (-1.7에서 -4.4)였으며, 평균 추시기간은 23개월(12–65개월)이었다. 수술법은 골절부의 내측에 먼저 광근 하방으로 접근하여 해부학적 정복을 시행하고 금속판으로 내고정을 시행한 후 추가로 외측에 최소 절개법을 통해 잠김 압박 금속판을 사용하여 내고정하였다. 골유합 기간 및 합병증, 최종 추시 시 Hospital for Special Surgery Knee Score (HSS)를 평가하였다. 결과: 평균 골유합 기간은 17.4주(7–40주)였으며 2예에서 지연 유합이 발생하였으나 추가적 수술 없이 36주와 40주에 골유합을 얻었다. 1예에서 불유합이 발생하여 재고정술 및 자가골 이식술을 시행 후 3개월에 완전한 골유합을 얻었다. 최종 추시 시 전후방 각형성은 평균 2.86도(0–4.9도), 내외반 각형성은 평균 1.67도(-1.2–4.9도)로 전체 예에서 부정 유합은 없었다. 최종 추시 시 슬관절 운동 범위는 평균 90도였고, HSS 점수는 평균 85점(70–95점)이었다. 결론: 슬관절 전치환술 후 발생한 대퇴골 삽입물 주위 골절 시 편측 고정만으로 골절부의 안정성을 얻을 수 없는 경우 이중 금속판을 이용한 내고정술은 안정적인 고정으로 빠른 재활이 가능하고 임상적으로 양호한 결과를 얻을 수 있는 방법으로 생각된다. Purpose: This study evaluated the results of dual plate fixation for periprosthetic femur fracture after total knee arthroplasty (TKA). Materials and Methods: From October 2007 to February 2013, 23 cases of periprosthetic femur fracture after TKA were treated at the author’s hospital. There were 13 cases of fixation using a medial and lateral dual plate when the stability of the fracture site could not be achieved by one side fixation with a follow-up of more than one year. The cases included no loosening of the femoral component in fractures that were categorized as Lewis–Rorabeck classification II and supracondylar comminuted fractures and elongation of the fracture line to the lateral epicondyle of the femur or stem in the medullary canal. The mean age was 72 years (65–82 years), and 11 cases were female. Three cases had a stem due to revision. The mean bone marrow density was -3.2 (-1.7 to -4.4), and the mean period from primary TKA to periprosthetic fractures was 28 months (1–108 months). The mean follow-up period was 23 months (12–65 months). The medial fracture site was first exposed via the subvastus approach. Second, the supplementary plate was fixed on the lateral side of the fracture using a minimally invasive plate osteosynthesis technique. The average union time, complications, and Hospital for Special Surgery Knee Score (HSS) at the last follow-up were evaluated. Results: The mean union time was 17.4 weeks (7–40 weeks). Two cases showed delayed bone union and nonunion occurred in one case, in whom bone union was achieved three months later after re-fixation using a dual plate with an autogenous bone graft. The mean varus-valgus angulation was 1.67 degrees (-1.2–4.9 degrees), and the mean anterior-posterior angulation was 2.86 degrees (0–4.9 degrees) at the last follow-up. The mean knee range of motion was 90 degrees, and the HSS score was 85 points (70–95 points) at the last follow-up. Conclusion: Dual plate fixation for periprosthetic femur fractures that had not achieved stability by one side plate fixation after TKA showed a good clinical result that allowed early rehabilitation.