• The Journal of Korean Physical Therapy
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• 제30권1호
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• pp.14-22
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• 2018

Purpose: This study examined the effects of the lower limb alignment on the pelvis, hip, and knee kinematics in people with genu varum during stair walking. Methods: Forty subjects were enrolled in this study. People who had intercondylar distance ${\geq}4cm$ were classified in the genu varum group, and people who had intercondylar distance <4cm and intermalleolar distance <4cm were placed in the control group. 3D motion analysis was used to collect the pelvis, hip, and knee kinematic data while subjects were walking stairs with three steps. Results: During stair ascent, the genu varum group had decreased pelvic lateral tilt and hip adduction at the early stance phase and decreased pelvic lateral tilt at the swing phase compared to the control group. At the same time, they had decreased minimal hip adduction ROM at the early stance and decreased maximum pelvic lateral tilt ROM and minimum hip rotation ROM at the swing phase. During stair descent, the genu varum group had decreased pelvic lateral tilt at the early stance and decreased pelvic lateral tilt and pelvic rotation at the swing phase. In addition, they had decreased pelvic frontal ROM during single limb support and increased knee sagittal ROM during the whole gait cycle. Conclusion: This study suggests that a genu varum deformity could affect the pelvis, hip and knee kinematics. In addition, the biomechanical risk factors that could result in the articular impairments by the excessive loads from lower limb malalignment were identified.

• 제어로봇시스템학회논문지
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• 제16권10호
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• pp.939-947
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• 2010

With the rising numbers of elderly and disabled people, the demand for welfare services using a robotic system and not involving human effort is likewise increasing. This study deals with a mobile-robot system combined with a BWS (Body Weight Support) system for gait rehabilitation. The BWS system is designed via the kinematic analysis of the robot's body-lifting characteristics and of the walking guide system that controls the total rehabilitation system integrated in the mobile robot. This mobile platform is operated by utilizing the AGV (Autonomous Guided Vehicle) driving algorithm. Especially, the method that integrates geometric path tracking and obstacle avoidance for a nonholonomic mobile robot is applied so that the system can be operated in an area where the elderly users are expected to be situated, such as in a public hospital or a rehabilitation center. The mobile robot follows the path by moving through the turning radius supplied by the pure-pursuit method which is one of the existing geometric path-tracking methods. The effectiveness of the proposed method is verified through the real experiments those are conducted for path tracking with static- and dynamic-obstacle avoidance. Finally, through the EMG (Electromyography) signal measurement of the subject, the performance of the proposed system in a real operation condition is evaluated.

• The Journal of Korean Physical Therapy
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• 제30권2호
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• pp.73-77
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• 2018

Purpose: The prefrontal lobe, supplementary motor area, cerebellum, and basal ganglia are activated during gait. In addition, gait is controlled by nerves, such as the corticospinal tract (CST) and corticoreticular pathway (CRP). In this study, the presence of an injury to the CST and CRP was identified by diffusion tensor imaging and the characteristics of the gait pattern were investigated according to inferior cerebral artery infarction. Methods: One patient and six control subjects of a similar age participated. A 69-year-old female patient had an injury to the left basal ganglia, insular gyrus, corona radiata, dorsolateral prefrontal cortex, and postcentral gyrus due to an inferior cerebral artery infarction. Diffusion tensor imaging (DTI) data was acquired 4 weeks after the stroke. The kinematic and spatio-temporal parameters of gait were collected using a three-dimensional gait analysis system. Results: On 4 weeks DTI, the CST and CRP in the affected hemisphere did not show injury to the affected and unaffected hemisphere. Gait analysis showed that the cadence of spatio-temporal parameter was decreased significantly in the patient. The angle of the knee joint was decreased significantly in the affected and unaffected sides compared to the control group. Conclusion: The results of diffusion tensor imaging showed that although the patient was evaluated to be capable of an independent gait, the quality and quantity of gait might be reduced. This study could help better understand the gait ability analysis of stroke patients and the abnormal gait pattern of patients with a brain injury.

• International Journal of Control, Automation, and Systems
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• 제6권4호
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• pp.534-543
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• 2008

To use the Global Positioning System (GPS) carrier phase measurement for precise positioning, the integer ambiguities at the early stage of most algorithms must be determined. Furthermore, if a precise positioning is to be applied to real time navigation, fast determination and validation methods for integer ambiguity are essential. In this paper, the Wald test that simultaneously determines and validates integer ambiguities is used with assistance of the Inertial Navigation System (INS) to improve its performance. As the Wald test proceeds, it assigns a higher probability to the candidate that is considered to be true at each time step. The INS information is added during the Wald test process. Large performance improvements were achieved in convergence time as well as in requiring fewer observable GPS satellites. To test the performance improvement of the Wald test with the INS information, experimental tests were conducted using a ground vehicle. The vehicle moved in a prescribed trajectory and observed seven GPS satellites. To verify the effect of the INS information on the Wald test, the convergence times were compared with cases that considered the INS information and cases that did not consider the INS information. The results show that the benefits of using the INS were emphasized as fewer GPS satellites were observable. The performance improvement obtained by the proposed algorithm was shown through the fast convergence to the true hypothesis when using the INS measurements.

• 폴리머
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• 제39권2호
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• pp.346-352
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• 2015

폴리알파올레핀(PAO)은 유동점, 점도지수, 열/산화 안정성이 광유 기반의 윤활유보다 우수한 합성 윤활유이다. 본 연구에서는 1-펜텐, 1-헥센, 1-옥텐, 및 1-도데센을 단량체로 사용하고 세가지 종류의 알루미늄계 루이스 산촉매로 양이온 중합을 수행하여 다양한 PAO를 합성하였다. PAO 중합 성능과 제조된 PAO의 분자량, 동점도, 유동점과 점도지수를 다양한 중합 조건에서 조절할 수 있었다. 알킬 알루미늄 할라이드계 촉매가 기존의 $AlCl_3$계 촉매에 비하여 촉매 성능이 우수하였다. PAO의 미세구조를 비행-시간형 질량분석기(TOF-MS) 해석을 통하여 PAO의 미세구조와 윤활유로의 성능(점도지수, 유동점)과의 상관관계를 규명하였다. 특히, PAO의 점도지수는 알파 올레핀의 탄소수 증가에 따라 상승하여, PAO의 분지길이가 점도지수와 밀접한 상관관계가 있음을 확인하였다.

• 한국운동역학회지
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• 제17권1호
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• pp.99-109
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• 2007

The purpose of the study is to examine the effect of the spring shoe through the comparison of spring shoe to general shoe. For this, 12 healthy females in the age from 20 to 30 years participated in the E.M.G. experiment with testing kinematic variables. Results indicated that there was significant differences in angle of ankel between the general and spring shoe. Specifically, the spring shoe showed a bigger angle of take on and a smaller angle of take off in walking than the general shoe. This mesns that the spring shoe does not have a significant effect to produce efficient and smooth walking. In addition, the spring shoes revealed a bigger rear-foot angle than the general shoe in the evaluation of rear-foot control function. This means that the rear-foot control function of the spring shoe is low compared to trhe general shoe. Meanwhile, there is no significant differences in angle of knee and angle of Achilles tendon between both shoes. In an analysis of E.M.G., the significant differences were found in gastrocnemius muscle, anterior tibial musculi, musculi rectus femoris, biceps muscle of thigh between both the general and spring shoe groups by the section. In the case of gastrocnemius muscle, the spring shoe showed a low muscle production of anterior tibial musculi than the general shoe. This is a result from structural nature of the sole of a foot of the spring shoe. The spring shoe performs a rolling movement through slightly large pronation toward front-foot from rear-foot in supprt time before taking-off of toe and the power for this movement is mainly produced from musculi rectus femoris.

• 한국전문물리치료학회지
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• 제23권3호
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• pp.48-56
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• 2016

Background: Recently, there has been an emphasis on the use of interventions with biofeedback information for the maintenance or correction of posture. Objects: This study assessed the change of trunk posture and trunk muscle activation when people exhibiting postural kyphosis performed visual display terminal work with or without a contact feedback device (CFD). Methods: Eighteen right-handed individuals were recruited. Thoracic angle and right thoracic erector spinae (TES) muscle amplitude were analyzed. There were two sessions in these experiments. The control session involved 16 minutes of typing without a CFD, and the CFD session involved 16 minutes of typing with a CFD. The visual analog scale score was analyzed with a paired t-test, and the kinematic and electromyography data were analyzed through two-way repeated analysis of variance. Results: The paired t-tests revealed that subjects had significantly less pain after the CFD sessions than after the control sessions (p<.05). Significant main effects by session and by time were observed in the thoracic kyphosis angle (p<.05). There was a significant session${\times}$time interaction for TES amplitude (p<.05), along with significant main effects by session and by time (p<.05). Conclusion: The CFD caused people with postural kyphosis to straighten and to activate their TES continuously, even though they were habituated to bend their bodies forward. Therefore, the CFD was a beneficial treatment tool.

• 농업과학연구
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• 제47권3호
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• pp.657-665
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• 2020

The objective of this study was to investigate whether supplementation of pentoxifylline (PTX; phosphodiesterase inhibitor) to thawed boar semen improves the post-thaw motility of sperm and affects the efficiency of artificial insemination (AI) and further development. To determine the concentration of PTX for AI, frozen-thawed semen was incubated with 0, 5, 10, and 20 mM PTX in an extender freezing medium, respectively, after thawing. Kinematic properties of sperm were examined with a computer-assisted semen analysis (CASA) system. In addition, viability and mitochondrial activity were also tested by LIVE/DEAD and a MitoTracker kit. There were no significant differences in the kinetic parameters of thawed sperm between control and treatment groups, but overall assessment parameters such as motility and rapid progressive were higher in the 10 mM PTX group. In the viability and mitochondrial assay, there were no significant differences observed in the PTX treatment, compared to the control. For further analysis, artificial inseminations were performed using frozen semen and 10 mM PTX treated cryopreserved semen, respectively. There were no differences in pregnancy rates and fetus weights among the groups until 30 and 40 days, but litter size was reduced and relatively low-birth weight was observed in the PTX group. In summary, our findings suggest that enhancement of in vitro sperm quality or non-toxicity supplemented by PTX may have detrimental effects on fetus development.

• 한국도로학회논문집
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• 제12권4호
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• pp.111-120
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• 2010

본 연구는 준고온 공법을 이용한 재생 아스팔트 콘크리트의 강도특성을 평가하기 위해 이루어졌다. 굵은 골재 최대치수 13mm의 화강암과 침입도 60-80인 신규 바인더 60-80을 재생 혼합물을 제조하는데 사용하였다. 배합설계는 RAP(굵은 입자 : 잔입자=6 : 4) 첨가비율 20%와 30%를 사용하였고 GPC, 침입도, 절대점도, 동점도를 준고온 첨가제(Evotherm와 Sasobit)의 첨가 함량을 결정하기 위하여 측정하였다. LD(low-density poly ethylene)를 본 연구에서 준고온 재생 아스팔트 혼합물의 개질제로 사용하였다. 본 연구에서는 8개의 준고온 재생 혼합물(2 RAP함량 ${\times}$ 2 준고온 첨가제 ${\times}$ 2 개질제)뿐만 아니라 2개의 일반 재생 혼합물, 1개의 가열혼합 일반혼합물(control)까지 총 11개의 혼합물을 제조하였다. 변형강도 시험, 간접인장강도 시험, 수분민감성 시험, wheel tracking을 통한 소성변형 시험을 준고온 재생혼합물의 기본 특성을 평가하기 위하여 수행하였다.

• Journal of Biosystems Engineering
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• 제43권4호
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• pp.379-385
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• 2018

Purpose: Postharvest handling of onions (harvesting, cleaning, grading, cooling, storing, and transport) should be performed continually to reduce costs and improve quality. The purpose of this study is to a) determine the design parameters and operating conditions of anion auto-dumping that constitutes a key component of the postharvest bulk handling machinery system, and b) to perform a performance test with the auto-dump prototype system. Methods: Kinematic analyses and computer simulations of the auto-dump mechanism were applied to analyze the operating conditions and design parameters. Results: The optimum working condition for the auto-dump was determined from kinetic analyses. In addition, the interaction between the velocity of the hydraulic cylinder and the angular velocity of the auto-dump were analyzed in order to control the bulk handling machinery system. The acting forces and optimum operating conditions of the hydraulic cylinder were determined by analyzing the forces related to the mass of inertia of the auto-dump assembly during rotation. The method of controlling the feeding rate of onions in terms of the uniformity of the stacking pattern and the control of the entire system was better than the two-stage method of controlling the rotational speed of the auto-dump. Based on the performance test with the prototype for the auto-dump, the stacking pattern and rigidity of the system were analyzed. Conclusions: These results would be of great importance in the postharvest bulk handling machinery system for onions.