• 대한기계학회논문집
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• 제18권2호
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• pp.260-270
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• 1994

With the prevalent use of robot, the interests in moving speed of robot have been increasing for the purpose of upgrading performance of production. But the faster robot manipulator moves, the worse working accuracies are. And mechanical vibration is more and more serious with the increment of the moving speed of robot. So, the study on the cause and control method of robot vibration is one of the points of issue in robotics. This paper focuses on the vibration of 3 DOF parallel link drive mechanism robot. We assume that links of robot manipulator are `rigid' and joints are `flexible elements'. Governing equations of robot system including controller, servo amplifier, D.C servo motor, transmission with elasticity, and manipulator dynamics are derived. On the basis of modelling, we define `controller stiffness' by the proportional gain of controller and `stiffness of transmission'. Numerical and experimental research is performed to study vibration phenomena of robot induced from the variation of these two defined stiffnesses, and its results are shown.

• 한국정밀공학회지
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• 제23권7호
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• pp.84-92
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• 2006

This paper deals with determination of motions of a humanoid robot using genetic algorithm. A humanoid robot has some problems of the structural instability basically. So, we have to consider the stable walking gait in gait planning. Besides, it is important to make the smoothly optimal gait for saving the electric power. A mobile robot has battery to move autonomously. But a humanoid robot needs more electric power in order to drive many joints. So, if movements of walking joint don't maintain optimally, it is hard to sustain the battery power during the working period. Also, if a gait trajectory doesn't have optimal state, the expected lift span of joints tends to be decreased. Also, if a gait trajectory doesn't have optimal state, the expected lift span of joints tends to be decreased. To solve these problems, the genetic algorithm is employed to guarantee the optimal gait trajectory. The fitness functions in a genetic algorithm are introduced to find out optimal trajectory, which enables the robot to have the less reduced jerk of joints and get smooth movement. With these all process accomplished by PC-based program, the optimal solution could be obtained from the simulation. In addition, we discuss the design consideration fur the joint motion and distributed computation of tile humanoid, ISHURO, and suggest its result such as structure of the network and a disturbance observer.

• 근관절건강학회지
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• 제15권2호
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• pp.175-182
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• 2008

Purpose: The purpose of the study was to identify low pain prevalence rate and factors affecting low back pain in emergency medical technicians. Method: A descriptive relationship research design was utilized. The participants were 74 emergency medical technicians who worked at fire stations in W and J city and agreed to participate in this study. Data were collected between April and August 2008 using a questionnaire, which included demographic factors, severity of low back pain using a visual analog scale, factors related to low back pain and health behavior, and BMI. Descriptive statistics and multiple regression were performed for data analysis. Results: 85.1% of emergency medical technicians experienced low back pain. The mean score of low back pain was relatively low (M=4.0, SD=2.33). Significant factors affecting low back pain were found to be age, marital status, exercise, hours of standing work, and BMI. These variables explained 35.1% of variance in low back pain (F=8.45, p<.001). Conclusion: These results suggest that further research is needed to develop interventions for prevention and management of low back pain among emergency medical technicians.

• 수산경영론집
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• 제46권3호
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• pp.15-29
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• 2015

The illegal, unreported and unregulated fishing can be properly regulated only if fishing activities, transhipment and landing of illegally caught fish, and processing of fish at sea involved in it are integrally managed. To do this, flag States, port States, coastal States, market States and relevant regional fisheries management organizations shall closely cooperate. In addition, fishing boats involved in IUU fishing often ignore requirements of safety of navigation so that they could be exposed to more causes of incidents and could have less chances to be rescued. Then, it seems to be necessary for the regulation on IUU fishing to include a certain consideration of strengthening safety of those ships. International Maritime Organization(IMO) has developed and implemented international rules for the safety of shipping. IMO has cooperated with Food and Agricultural Organization on IUU fishing since 2000 and the third joint meeting is scheduled in November 2015. This paper reviews the recommendations adopted in the previous meetings, and the measures actually taken as a result of the cooperation and, in particular, focus on the additional roles of IMO for the eradication of the IUU fishing.

• Structural Engineering and Mechanics
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• 제63권5호
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• pp.691-702
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• 2017

Clearances are essential for the assemblage of mechanisms to allow the relative motion between the joined bodies. This clearance exists due to machining tolerances, wear, material deformations, and imperfections, and it can worsen the mechanism performance when the precision and smoothly-working are intended. Energy is a subject which is less paid attention in the area of clearance. The effect of the clearance on the energy of a flexible slider-crank mechanism is investigated in this paper. A clearance exists in the joint between the slider and the coupler. The contact force model is based on the Lankarani and Nikravesh model and the friction force is calculated using the modified Coulomb's friction law. The hysteresis damping which has been included in the contact force model dissipates energy in clearance joints. The other source for the energy loss is the friction between the journal and the bearing. Initial configuration and crank angular velocity are changed to see their effects on the energy of the system. Energy diagrams are plotted for different coefficients of friction to see its influence. Finally, considering the coupler as a flexible body, the effect of flexibility on the energy of the system is investigated.

• 근관절건강학회지
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• 제19권3호
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• pp.350-361
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• 2012

Purpose: The purpose of this study is to explore the level of bone mineral densities of the femur neck and to identify factors affecting bone mineral density of the femur in Parkinson's disease (PD) patients. Methods: Participants were 121 PD patients visiting the outpatient clinic of D University Hospital in B City. Bone mineral density was measured at the femur neck by using a dual-energy x-ray absorptiometry. The serum vitamin D level, the amounts of milk intake, caffeine intake, cigaret smoking, and alcohol consumption, and the number of steps taken daily were measured. Past and present disease history, the medication history, and duration of the disease were also collected. The level of disability was obtained by neurologists using the Hoehn and Yahr stage and the Unified Parkinson's Disease Rating Scale. Results: Among PD patients, 57% had osteopenia and 15.7% had osteoporosis. The bone mineral density of the femur was associated with weight, serum vitamin D level, age, and working status. Conclusion: The identification of weight and serum vitamin D level as important predictive factors emphasizes the importance of balanced nutrition for PD patients.

• 근관절건강학회지
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• 제27권1호
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• pp.50-60
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• 2020

Purpose: This study aimed to identify the effects of preceptor's leadership, preceptor-preceptee exchange relationship, and preceptee's self-leadership on newly hired nurses' turnover intention. Methods: Participants were 175 nurses working at general hospitals in D city. Data were collected from 164 nurses in May 2019 and were analyzed using multiple linear regression with SPSS/WIN 24.0 program. Results: Newly hired nurses' turnover intention was negatively correlated with preceptor's transactional leadership (r=-.23, p=.003), preceptor's emotional leadership (r=-.28, p<.001), preceptor-preceptee exchange relationship (r=-.34, p<.001), and preceptee's self-leadership (r=-.23, p=.004). The work unit (β=.35, p<.001), preceptor-preceptee exchange relationship (β=-.28, p=.002), present work experience (β=.27, p=.043), and marital status (β=-.19, p=.009) were significant predictors of the turnover intention (R²=.26, p<.001). Conclusion: Therefore, in order to reduce the degree of turnover of new nurses, improving the exchange relationship of preceptor-preceptee is required, and balancing between work and life should be considered especially for the married new nurses.

• 대한기계학회논문집A
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• 제37권12호
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• pp.1521-1527
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• 2013

본 논문에서는 마스터 조정자인 인간의 근육강도과 관절변위를 측정하여 슬레이브장치가 외부환경에 맞는 작업능력을 발휘할 수 있는 마스터/슬레이브 원격조정시스템을 제안한다. 외골격형 기구부와 경량의 관성센서를 사용하여 마스터 착용자의 편리성을 높였으며 인간의 근육과 동일한 운동특성을 가진 공압인공근육으로 슬레이브 기구장치를 구성하여 운동의 모사능력을 향상시켰다. 실험을 통해서 단순히 마스터의 위치정보만 전달하는 원격조정에 비해서 제안된 마스터는 인간 조정자가 근력의 세기를 조절함으로써 슬레이브에 작용하는 가반하중의 변화에 관계없이 균일한 제어성능을 가질 수 있었다.

• 근관절건강학회지
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• 제28권2호
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• pp.140-151
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• 2021

Purpose: This descriptive research study aimed to investigate the effect of social networks and information literacy competency on the job competency of community health practitioners. Methods: The participants of this study were 170 community health practitioners working in the southern and northern regions of J, Korea. Data collection was carried out from March 6, 2018, to April 17, 2018, using a structured self-report questionnaire. Data were analyzed using the SPSS / WIN 23.0 statistical program. Results: Information literacy competency showed 45.5% explanatory power for job competency. However, there was no significant relationship between social networks and job competency. Conclusion: It is helpful to establish a systematic education system for job training and to expand educational opportunities using varied methods like online or mobile-based teaching to increase the job competency of community health practitioners.

• Clinics in Orthopedic Surgery
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• 제10권4호
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• pp.508-512
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• 2018

Foraminal decompression using a minimally invasive technique to preserve facet joint stability and function without fusion reportedly improves the radicular symptoms in approximately 80% of patients and is considered one of the good surgical treatment choices for lumbar foraminal or extraforaminal stenosis. However, proper decompression was not possible because of the inability to access the foramen at the L5-S1 level due to prominence of the iliac crest. To overcome this challenge, endoscopy-based minimally invasive spine surgery has recently gained attention. Here, we report the technical skills required in unilateral extraforaminal biportal endoscopic spinal surgery using a $30^{\circ}$ arthroscope to enable foraminal decompression at the L5-S1 level. Two 0.8-cm portals were created 2 cm lateral from the lateral border of the pedicles at the L5-S1 level. After sufficient working space was made, half of the superior articular process (SAP) in the hypertrophied facet joint was removed using a high-speed burr and a 5-mm wide osteotome, whereas the remaining inside part of the SAP was removed using a Kerrison punch and pituitary punch. The foraminal ligamentum flavum should be removed to inspect the conditions of the L5 exiting root and disc. Removing of the extruded disc could decompress the L5 root. The extraforaminal approach using a $30^{\circ}$ arthroscope is considered a minimally invasive alternative technique for decompressing foraminal stenosis at the L5-S1 level that preserves facet stability and provides symptomatic relief.