• Physical Therapy Korea
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• v.13 no.4
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• pp.23-29
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• 2006

The purpose of the present study was to examine gaze effects on spatial and kinematic characteristics during a pointing task. Subjects were asked to watch and point to an aimed target (2 mm in diameter) displayed on a vertically mounted board. Four gaze conditions were developed as combinations of "seeing-aiming" in terms of the eye movements: Focal-Focal (F-F), Focal-Fixing (F-X), Fixing-Focal (X-F), and Fixing-Fixing (X-X). Both the home target and an aimed target were presented for 1 second and then were disappeared in F-F and X-F. In X-F and X-X, only an aimed target disappeared after 1 second. Subjects were asked to point (with index finger tip) to an aimed target accurately as soon as the aimed target was removed. A significant main effect of gaze was found (p<.01) for normalized movement time. Peripheral retina targets had significantly larger absolute error compared to central retina targets on the x (medio-lateral) and z (superior-inferior) axes (p<.01). A significant undershooting to peripheral retina targets on the x axis was found (p<.01). F-F and X-F had larger peak velocities compared to F-X and X-X (p<.01). F-F and X-F were characterized by more time spent in the deceleration phase compared to F-X and X-X (p<.01). The present study demonstrates that central vision utilizes a form of on-line visual processing to reach to an object, and thus increases spatial accuracy. However, peripheral vision utilizes a relatively off-line visual processing with a dependency on proprioceptive information.

• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1202-1211
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• 2018

In this paper, induction machine operation efficiency and torque is improved using Machine Learning based Gene Optimization (ML-GO) Technique is introduced. Optimized Genetic Algorithm (OGA) is used to select the optimal induction machine data. In OGA, selection, crossover and mutation process is carried out to find the optimal electrical machine data for induction machine design. Initially, many number of induction machine data are given as input for OGA. Then, fitness value is calculated for all induction machine data to find whether the criterion is satisfied or not through fitness function (i.e., objective function such as starting to full load torque ratio, rotor current, power factor and maximum flux density of stator and rotor teeth). When the criterion is not satisfied, annealed selection approach in OGA is used to move the selection criteria from exploration to exploitation to attain the optimal solution (i.e., efficient machine data). After the selection process, two point crossovers is carried out to select two crossover points within a chromosomes (i.e., design variables) and then swaps two parent's chromosomes for producing two new offspring. Finally, Adaptive Levy Mutation is used in OGA to select any value in random manner and gets mutated to obtain the optimal value. This process gets iterated till finding the optimal value for induction machine design. Experimental evaluation of ML-GO technique is carried out with performance metrics such as torque, rotor current, induction machine operation efficiency and rotor power factor compared to the state-of-the-art works.

• Journal of Family Relations
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• v.21 no.3
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• pp.3-23
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• 2016

Objectives: The purpose of this study is to examine the effects of symptoms of dementia elderly on the primary caregiver's depression. In addition, moderating effect of family support was examined. Based on the results, the necessity for intervention in the level of social welfare as a way to mitigate primary caregiver's depression was suggested. Method: In order to accomplish these purposes, a total of 197 who are spouse and adult-children of dementia elderly using day care facilities or services in Seoul, Gyeonggi, Busan province, South Korea were utilized. Data were analyzed by frequency analysis and descriptive statistics, regression model analysis with SPSS 18.0. Results: In case of analysis results, the mean value was reported 0.9 out of four point about primary caregiver's depression and the mean value of family support was reported 3.34 out of five point. And besides, the analysis result of dementia elderly's symptoms showed that prevalence of depression/dysphoria were 62.2%, prevalence of aberrant motor were 61.3%, prevalence of apathy/indifference were 56.6%. Crucial findings are as follows: the symptoms of dementia elderly was significantly associated with the primary caregiver's depression. At the same time, family support significantly influenced lower level of the primary caregiver's depression. While, in the relationship between the symptoms of dementia elderly and the primary caregiver's depression, family support has a moderation effect by important protection factor. Conclusions: From these findings, the necessities to provide the care service for dementia elderly to help improve symptoms of dementia as well as the policy and service to manage the mental health of the family as primary caregiver were suggested. Also, the necessities to provide the family therapy program to improve the relationship with family members were suggested.

• The Journal of Korea Robotics Society
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• v.18 no.3
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• pp.251-259
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• 2023

In the path traveling of differential-drive robots, the steering controller plays an important role in determining the path-following performance. When a robot with a pure-pursuit algorithm is used to continuously drive a right-angled driving path in an unstructured environment without turning in place, the robot cannot accurately follow the right-angled path and stops driving due to the ground and motor load caused by turning. In the case of pure-pursuit, only the current robot position and the steering angle to the current target path point are generated, and the steering component does not reflect the speed plan, which requires improvement for precise path following. In this study, we propose a driving algorithm for differentially driven robots that enables precise path following by planning the driving speed using the radius of curvature and fusing the planned speed with the steering angle of the existing pure-pursuit controller, similar to the Model Predict Control control that reflects speed planning. When speed planning is applied, the robot slows down before entering a right-angle path and returns to the input speed when leaving the right-angle path. The pure-pursuit controller then fuses the steering angle calculated at each path point with the accelerated and decelerated velocity to achieve more precise following of the orthogonal path.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.953-965
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• 2023

The stratospheric drones are developed to perform missions such as weather observation, communication relay, surveillance, and reconnaissance at 18km to 20km, where climate change is minimal and there is no worry about a collision with aircraft. It uses solar panels for daytime flights and energy stored in batteries for night flights, providing many advantages over existing satellites. The electrical and power systems essential for stratospheric drone flight must ensure reliability, efficiency, and lightness by selecting the optimal circuit topology. Therefore, it is necessary to analyze the circuit topology of various types of multi-level inverters with high redundancy that can ensure the reliability and efficiency of the motor driving power required for stable long-term flight of stratospheric drones. By quantifying the switch element voltage drop and the number and weight of inverter components for each topology, we evaluate efficiency and lightness and propose the most suitable circuit topology for stratospheric drones.

• International Journal of Automotive Technology
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• v.7 no.4
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• pp.485-492
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• 2006

The AA5182/polypropylene/AA5182(AA/PP/AA) sandwich sheets have been developed for application to automotive body panels in future lightweight vehicles with significant weight reduction. It has been reported that the AA5182 aluminum sheet shows $L\"{u}ders$ band because of dissolved Mg atoms that cause fabrication process problem, especially surface roughness. The examination of serration behavior has been made after the tensile deformation of the AA/PP/AA sandwich sheets as well as that of the AA5182 aluminum skins at room and elevated temperatures. All sandwich sheets and the AA5182 aluminum skin showed serration behavior on their flow curves. However, the magnitude of serration was significantly diminished in the sandwich sheet with high volume fraction of the polypropylene core. According to the results of the analysis of the surface roughness following the tensile test, $L\"{u}ders$ band depth of the sandwich sheet evidently showed lower than that of the AA5182 aluminum skin. The strain rate sensitivity, m-value, of the AA5182 aluminum skin was -0.006. By attaching these skins to the polypropylene core, which has relatively large positive value of 0.050, m-value of the sandwich sheets changed to the positive value. The serration mechanism of the sandwich sheets was quantitatively investigated in the point of the effect on polypropylene thickness variation, that on the strain rate sensitivity and that on the localized stress state.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.3
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• pp.10-16
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• 2005

Recently, the international regulations about the exhaust emissions of the motorcycle have been strengthened. The electrically controlled fuel injection type motorcycle has been emphasized to meet with this regulation. However, since the pulsation phenomenon happens in the intake port of the motorcycle because of the characteristic of high speed and the smaller layout than the passenger car, there are many difficulties to select the factor about control parameters needed to develop the ECU system. In this paper, the pulsation values measured from the engine test were compared with the calculated one by WAVE, and it was analyzed the pulsation characteristic according to the driving condition and estimated the mass flow rate. This research showed that the lowest point of the pressure gets lowin the low load and the pulsation of pressure were increased in the high load. Also, the simulation program was verified by showing good prediction of the pulsation and air mass flow rate.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3180-3186
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• 2011

A segmented scissors type switch has been developed for the urban transit maglev demonstration line to be commercialized near Incheon International Airport in 2013. Based on the design of the previous segmented 3-way switch, the scissors switch is composed of four segmented 2-way switches up/down and left/right and a turn table in the mid point. The main function of the scissors switch is to change the running direction of the train at end terminals. The developed scissors switch is planned to be installed in front of the 102 station, which has a side platform, of the demonstration line. The total length of the switch is 65m and the distance between the up and down track centerlines is 6m. The 2-way switches and turn table are made of steel box type beams, and have their own driving unit, locking unit, control unit, levitation and propulsion rails, and so on. Installed in the factory, a 100,000-cycle continuous operation test was carried out after manual and automatic test operations. The applicapability of the developed switch was verified through the measurements of the linearity of the track after repetitive operations, the mechanical operation noise, the load of the main driving motor, the safety of the control panel, the natural frequency of the girder, the deformation of the girder, and so on.

• Archives of Craniofacial Surgery
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• v.17 no.1
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• pp.28-30
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• 2016

Major maxillofacial bone injury itself can be life threatening from both cardiovascular point of view, as well as airway obstruction. Significant hemorrhage from facial fracture is an uncommon occurrence, and there is little in the literature to guide the management of these patients. We report a 73-year-old male driver who was transported to our hospital after a motor vehicle collision. The patient was hypotensive and tachycardic at presentation and required active fluid resuscitation and transfusion. The patient was intubated to protect the airway. All external attempts to control the bleeding, from packing to fracture reduction, were unsuccessful. Emergency angiogram revealed the bleeding to originate from terminal branches of the sphenopalatine artery, which were embolized. This was associated with cessation of bleeding and stabilization of vital signs. Despite the age and severity of injury, the patient recovered well and was discharged home at 3 months with full employment. In facial trauma patients with intractable bleeding, transcatheter arterial embolization should be considered early in the course of management to decrease mortality rate.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2000-2003
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• 2003

In recent years, robots have been used widely in industrial field and have been expanded as a result of continuous research and development for high-speed and miniaturization. The goal of this paper is to design the serial manipulator through kinematic analysis and to control the position and orientation of end-effector with respect to time. In general, a structure of industrial robot consists of several links connected in series by various types of joints, typically revolute and prismatic joints. The movement of these joints is determined in inverse kinematic analysis. Compared to the complicated structure of parallel and hybrid robot, open loop system retains the characteristic that each link is independent and is controlled easily. AC servo motor is used to place the robot end-effector toward the accurate point with the desired speed and power while it is operated by position control algorithm. The robot end-effector should trace the given trajectory within the appropriate time. The trajectory of end-effector can be displayed on the monitor of general personal computer through Opengl program.