• 한국운동역학회지
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• 제19권2호
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• pp.205-215
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• 2009

계단 하강보행에서의 임산부 낙상은 임산부와 태아에게 치명적인 영향을 미친다. 이 연구는 임신기간 중 계단의 단 너비 변화에 따른 임산부 양발 보행의 생체역학적 변화를 구명하는 것이다. 이 실험을 위하여 건강한 임산부 9명이 참가하였고 Qualisys사의 Proreflex MCU-240 카메라 7대와 Kistler사의 Type 9286AA 지면반력기 2대를 설치하여 상호 동조하여 실험하였으며 연구변인은 Visual 3D(C-motion Inc., USA)를 사용하여 인체를 모델링 한 후 산출하였다. 임신기간이 경과됨에 분당 활보장수는 감소한 반면 활보장 주기는 증가하였으며 양발의 슬관절 모멘트 차이가 작아졌다. 그리고 단너비가 넓어질수록 속력과 활보장 길이가 증가하였다. 단너비에 따른 하지 관절모멘트는 각 관절마다 고유한 패턴을 보였으며 고관절 모멘트는 주로 양발의 비대칭성 패턴을 보였고 슬관절 및 족관절은 대칭적인 패턴을 보였다. 그리고 임신기간이 경과됨에 따라 좌 우측의 최대 최소 슬관절 모멘트의 차이가 작아졌다. 이러한 결과들은 임산부가 신체변화에 적응하면서 안전성의 최대화를 위하여 자신의 고유한 보행패턴을 생성하는 자기적응화 과정을 지속적으로 유지하면서 변화한다고 할 수 있다.

• 대한정형외과학회지
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• 제56권2호
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• pp.103-116
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• 2021

삼차원(three-dimensional, 3D) 프린팅의 사용은 점차 보편화되고 있으며 정형외과 영역에서도 그 활용이 늘어나고 있다. 현재 정형외과에서 3D 프린팅 기술을 사용하는 방법은 크게 네 가지로 첫째, 3D 프린팅 모델을 이용한 수술 계획 수립 및 수술 시뮬레이션, 둘째, 환자 맞춤형 수술 기구, 셋째, 3D 적층 기법을 이용한 인공 삽입물의 생산, 넷째, 3D 프린팅으로 제작된 환자 맞춤형 삽입물이다. 3D 프린팅 기술을 사용할 수 있는 정형외과의 영역은 견관절, 척추, 고관절 및 골반, 슬관절, 족관절, 종양 분야 등으로, 각각의 영역마다 다루는 질환 및 특성이 다르기 때문에 3D 프린팅 기술을 사용하는 방법 역시 각각의 영역에 따라 약간의 차이가 있다. 하지만 모든 영역에서 3D 프린팅 기술을 이용하는 것은 수술의 효율을 높여 주고, 수술 시간을 단축시키며 수술 중 방사선 노출을 줄여 준다. 3D 프린팅 기술은 특히 복잡하고 어려운 질환이나 골절 환자의 치료에 큰 도움을 줄 수 있다. 따라서 정형외과 의사는 이러한 3D 프린팅 기술의 장점을 이해하고 임상에 최대한 적용하여 효율적인 환자의 치료가 이루어질 수 있도록 해야 한다.

• 한국식생활문화학회지
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• 제27권4호
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• pp.407-413
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• 2012

In previous studies, we performed joint animal studies and clinical trials between Yonsei University and Oryza Oil & Fat Chemical Co. Ltd. We have shown that coffee bean extract has potent anti-obesity and hypotriglyceridemic activities as well as beneficial effects on body fat reduction.In this study, the effects of coffee bean extract (100 mg/capsule) on body fat reduction were evaluated in overweight/obese women (body mass index of 25~30 $kg/m^2$ or body fat > 30%) not diagnosed with any type of disease. Subjects were randomly assigned to a coffee bean extract group (n=10) or placebo group (n=10). We measured anthropometric parameters, abdominal fat distribution by computed tomography and blood components before and after the 8week intervention period. After supplementation, the coffee bean extract group showed body weight (p=0.08), body mass index (p=0.06), hip circumference (p<0.05), and upper waist circumference (p< 0.01). In addition, after 8 weeks, the coffee bean extract group showed a significant decrease in abdominal internal fat area compared to 0 weeks (0 weeks : $155.8cm^2$; 8 weeks : $145.9cm^2$, ${\Delta}$ change : $-9.9cm^2$, respectively). However, there were no significant differences in lipid profiles or serological measurements between the coffee bean extract group and placebo group. The results of our human study demonstrated that coffee bean extract supplementation for 8 weeks has beneficial effects on reducing abdominal internal fat area as well as hip and waist circumferences.

• 대한의용생체공학회:의공학회지
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• 제34권4호
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• pp.197-203
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• 2013

The purpose of this study was to analyze the asymmetry of the reaction forces on lower limbs between dominant and nondominant sides during sit-to-stand movement in normal subjects. Fourteen normal subjects ($22.6{\pm}2.3yrs$, all men) participated in this study. To measure the reaction forces during sit-to-stand movement, two force plates were mounted on the ground and one dual top force plate was mounted on a chair. Five events(movement onset, max thigh reaction force, transition, max hip angle, seat off) were determined from the reaction force and joint angle trajectories. For each of thigh, foot, and total reaction forces, two-way ANOVA was performed with the events and sides as factors. Also investigated was the leg asymmetry expressed as the ratio of the reaction forces of dominant and nondominant sides. The significance of asymmetry was investigated and two-way ANOVA was performed with the events and body parts(foot, thigh and total) as factors. Thigh reaction force and total reaction force showed interaction of events and leg sides(p < 0.01). Post-hoc comparisons showed they were different between sides at the latter stage(transition, max hip angle, and seat off events) (p < 0.01). Asymmetry was also significant at the latter stage(transition, max hip angle, and seat off events) (p < 0.01). Interaction of events and body parts on asymmetry was significant(p < 0.01) and asymmetry was greater in thigh reaction forces than total and foot reaction forces at the events of the latter stage(p < 0.01). The results suggest that asymmetry exist in normal subject and should be fully considered when investigating sit-to-stand strategy of patients.

• Nuclear Engineering and Technology
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• 제42권6호
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• pp.662-669
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• 2010

To develop the manufacturing methods for the blanket first wall (FW) of the International Thermonuclear Experimental Reactor (ITER) and to verify the integrity of the joint, Be/Cu mockups were fabricated and tested at the KoHLT-1 (Korea Heat Load Test facility), a graphite heater facility located at the Korea Atomic Energy Research Institute (KAERI). Since Be and Cu joining is the focus of the present study, the fabricated mockups had a CuCrZr heat sink joined with three Be tiles as an armor material, unlike the original ITER blanket FW, which has a stainless steel structure and coolant tubes. Hot isostatic pressing (HIP) was carried out at $580^{\circ}C$ and 100 MPa for 2 hours as the method for Be/Cu joining. Three interlayers, namely, $1{\mu}mCr/10{\mu}mCu$, $1{\mu}mTi/0.5{\mu}mCr/10{\mu}mCu$, and $5{\mu}mTi/10{\mu}mCu$ were applied as a coating to the Be tiles by a physical vapor deposition (PVD) method. A shear test was performed with the specimens, which were fabricated by the same methods as those used to fabricate the mockups. The average values were 125 MPa to 180 MPa, and the samples with the $1{\mu}mCr/10{\mu}mCu$ interlayer showed the lowest value. No defect or delamination was found in the joints of the mockups by the developed ultrasonic test using a flat-type probe with a 10 MHz frequency and a 0.25 inch diameter. High heat flux (HHF) tests were performed at $1.0\;MW/m^2$ heat flux for each mockup using the given conditions, and the results were analyzed by ANSYS-CFX code. For the test criteria, an expected fatigue lifetime about 1,000 cycles was obtained by analysis with ANSYS-mechanical code. Mockups using the interlayers of $1{\mu}mTi/0.5{\mu}mCr/10{\mu}mCu$ and $5{\mu}mTi/10{\mu}mCu$ survived up to 1,100 cycles over the required number of cycles. However, one of the Be tiles in the other two mockups using the $1{\mu}mCr/10{\mu}mCu$ interlayer was detached during the screening test, and others were detached by discharge after 862 cycles. The integrity of the joints using the proposed interlayers was proven by the HHF test, but the other interlayer requires more study before it can be used for the joining of Be to Cu. Moreover, it was confirmed that the measured temperatures agreed well with the analysis temperatures, which were used to estimate the lifetime and that the developed facility showed its capability of the long time operation.

• 한국운동역학회지
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• 제25권4호
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• pp.413-421
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• 2015

Objective : The purpose of this study was to investigate biomechanical changes of the lower limb including dynamic stability with changes in illumination (300Lx, 150Lx, and 5Lx) and slope (level and $15^{\circ}$ downhill) as risk factors for elderly falls. Method : Fifteen elderly females were selected for this study. Seven infrared cameras (Proreflex MCU 240: Qualisys, Sweden) and an instrumented treadmill (Bertec, USA) surrounded by illumination regulators and lights to change the levels of illumination were used to collect the data. A One-Way ANOVA with repeated measures using SPSS 12.0 was used to analyze statistical differences by the changes in illumination and slope. Statistical significance was set at ${\alpha}=.05$. Results : No differences in the joint movement of the lower limbs were found with changes in illumination (p>.05). The maximum plantar flexion movement of the ankle joints appeared to be greater at 5Lx compared to 300Lx during slope gait (p<.05). Additionally, maximum extension movement of the hip joints appeared to be greater at 5Lx and 150Lx compared to 300Lx during slope gait (p<.05). The maximum COM-COP angular velocity (direction to medial side of the body) of dynamic stability appeared to be smaller at 150Lx and 300Lx compared to 5Lx during level gait (p<.05). The minimum COM-COP angular velocity (direction to lateral side to the body) of dynamic stability appeared smaller at 150Lx compared to 5Lx during level gait (p<.05). Conclusion : In conclusion, elderly people use a stabilization strategy that reduces walk speed and dynamic stability as darkness increases. Therefore, the changes in illumination during gait induce the changes in gait mechanics which may increase the levels of biomechanical risk in elderly falls.

• 제어로봇시스템학회논문지
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• 제20권2호
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• pp.223-231
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• 2014

Humanoid robot is the most suitable robot platform for effective human interaction and various intelligent services. The present work addresses development of real time wireless control application of humanoid robot's forward and backward walks, and turning in walking. For convenience of human users, the application is developed on Android OS (Operating System) working on his or her smartphone. To this end, theoretic background on various-directional biped walking is proposed based on joint trajectories for forward walking, which have been shaped with a global optimization method. In this paper, backward walking is scheduled by interchange of angles and angular velocities and additional change of signs in angular velocities at all the via-points connecting cubic polynomial trajectories. Turning direction in walking is also implemented by activating the transversal hip joint initially located in the support leg in two stages. After validation of the proposed walking schemes with Matlab simulator, a smartphone application for the omnidirectional walking has been developed to control a humanoid robot platform named DARwIn-OP interconnected via Wi-Fi. Experiment result of the present wireless control of a humanoid robot with smartphone is successful, and the application will be released in application market near future.

• Corrosion Science and Technology
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• 제17권2호
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• pp.68-73
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• 2018

Substitution of hip and knee joints by CoCr alloys is in great demand due to their high wear resistance and good biocompatibility. Understanding of tribocorrosion in joint replacements requires study of variables such as coefficient of friction and the choice of a proper corrosive medium in wear-corrosion tests carried out in the lab. The objective of this study was to characterize tribocorrosion behaviour of CoCr alloy with low (LCCoCr) and high carbon (HCCoCr) contents in several corrosive media: NaCl, Phosphate Buffer Solution (PBS), and PBS with hyaluronic acid (PBS-HA). Tribocorrosion tests were carried out on a pin-on-disk tribometer with an integrated electrochemical cell. A normal load of 5N was applied on the alumina ball counterpart at a rotation rate of 120 rpm. Coefficient of friction (COF) was measured and tribocorrosion behaviour was characterized by in situ application of electrochemical techniques. HCCoCr alloy immersed in PBS-HA showed the best tribocorrosion behaviour with the lowest COF. In this case, in situ measurement of corrosion potential and the impedance data under wear corrosion process showed an active state while passive film was continuously destroyed without possibility of regeneration.

• 한국운동역학회지
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• 제18권1호
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• pp.97-105
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• 2008

수영과 핀수영의 스타트 동작의 운동학적 변인들을 3차원 영상분석법으로 비교분석하였다. 수영 스타트에서는 상지는 후상방으로 몸통은 전상방으로 이동했다가 전하방으로 하강하는 양상을 보인 반면 핀수영 스타트에서는 모든 분절이 전하방으로 이동하는 양상을 보였다. 수영 스타트에서 신체중심은 멀리 전방으로 수평 이동하다가 하방으로 급격히 이동하는 반면 핀수영 스타트에서의 중심은 짧은 시간에 전하방으로 가깝게 이동하는 것으로 나타났다. 입수 시 수영의 중심은 수직 속도가 핀수영의 중심은 수평속도가 높게 나타났다. 수영과 핀수영 모두 상지의 속도가 하지보다 더 신체중심의 속도에 영향을 미치는 것으로 나타났다. 핀수영 스타트에서 고관절은 점프 전에 굴곡을 하는 반면 수영에서는 점프 후 공중에서 2번 굴곡을 하는 것으로 나타났다. 핀수영의 슬관절 굴곡 신전운동이 수영보다 더 급격한 것으로 나타났다.

• 한국산업경영시스템학회:학술대회논문집
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• 한국산업경영시스템학회 2002년도 춘계학술대회
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• pp.243-257
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• 2002

A study on processing for producing cure seat radiated by Original Infrared Rays and Magnatic force. We are well aware that Original Infrared Rays and Magnatic force influence on our human body benificially. In the technical background of this research product, we treated that the product has some operations of ceramic hardwood charcoal, far infrared rays and magnetic, so it can serve large part curative values made of far infrared rays and magnetic force of ceramics. Also, in the special quality of the product deal with ceramic, hard charcoal, ferrite, gelatin what is needed in production. And among them, ferrite, ceramic and hard charcoal are introduced by the manufacturing process of the moleculeization. In concluding, this study described the manufacturing process on the basis of the worksheets and arranged the useful effect which effect on human body. There are so many symptoms in the pain of muscle. It's very various. for example, it is the cause of the liver, the spleen and a kidney function's weakening. the cause of the backbone subluxation, the cause of the shoulder joint and scapula, the cause of the sacrum and iliacjoint, the cause of hip joint and the cause of a sprain. In this thesis, we mainly deal with the method which the muscle and nervous system disease by fatigue and a sprain cure seat radiated by Original Infrared Rays and Magnatic force. then, Original Infrared Rays and Magnatic force pack up frapezius muscle, gluteus minimum muscle, gluteus medius muscle, gluteus maximus muscle, pririformis muscle around the spine. through this course the moral pressure by the nervous system disease can be treat.