• Journal of Advanced Navigation Technology
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• v.16 no.6
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• pp.1123-1133
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• 2012

This study configuration Vector Control System which is stable and has outstanding Dynamic Characteristics in Very Low Speed Region and Low Speed Region, and proposes Instantaneous Speed Observer and Very Low Speed Control method and vector control system of the speed estimation a using Reduced-Dimensional State Observer. The Observer proposed in this system, by appling Reduced-Dimensional State Observer to Load-Torque estimation and using for speed estimation, implements system composition simply and is capable of accurate Instantaneous Speed estimation in Very Low Speed Region. Also, this study reduces influence by System Noise and suggests an induction motor speed control system which is effective in Load Disturbance, modeling error, estimation noise and so on without changing pole of an Observer.

• Journal of the Korean Dietetic Association
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• v.18 no.1
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• pp.43-58
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• 2012

This study was designed to investigate the impact of a 12-week nutrition education program on 32 male industrial workers (average age: $44.5{\pm}3.8$ yrs, work duration period: $20.1{\pm}5.6$ yrs) diagnosed as having dyslipidemia in a medical checkup at their workplace. This program was implemented with a conceptual framework on strengthening self-efficacy for the improvement of the health conditions of the workers. Most of all, the study exhibited benefits in the industrial workers by ameliorating the risk factors associated with dyslipidemia via changes in dietary behaviors, nutritional knowledge, and attitudes, as well as anthropometric and biochemical parameters. After the nutrition education, overall lifestyle, including the ratios of smoking (P<0.05) and drinking (P<0.01), significantly improved. Exactly 65.6% of the subjects reported that their dietary habits changed. Body weight, BMI, percentage of body fat, and waist circumference all significantly decreased (P<0.001). The systolic (P<0.01) as well as diastolic blood pressures (P<0.001) decreased. Moreover, the degree of increase in serum HDL-cholesterol was appreciable (P<0.001), and the atherogenic index also decreased (P<0.01). Further, risk factors related to metabolic syndrome in subjects significantly decreased (P<0.001). The average scores for nutrition knowledge increased from 9.3 to 17.7 points (P<0.001). All of the participants agreed on the need for a nutrition education program at their workplace. Further, it should be pointed out that the participants strongly indicated the need for continuing nutrition intervention.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.2
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• pp.178-184
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• 2016

The motor power of the industry to use the electric energy is gradually increased. The electric motor generates a voltage drop in the starting current during startup. The starting current is started it is difficult to have an adverse effect on neighboring power systems with large motor starting when the voltage drop across the power grid. In addition to that the motor torque according to the load depending on the size of the rotation speed is changed to a motor start-up speed is important. However, the distance to the emergency generator transformers or motors from the motor capacity is smaller but short and difficult to maneuver the theory and practice of the operating characteristics of the starting characteristics of the motor used a lot of large industrial plants were measured and analyzed. Therefore, this study investigated the motor starting Analysis and interpretation for the relationship with the large motor starting torque and speed during motor starting.

• Journal of Power Electronics
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• v.15 no.3
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• pp.753-762
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• 2015

This paper presents a nonlinear sliding mode control (SMC) scheme with a variable damping ratio for interior permanent magnet synchronous motors (IPMSMs). First, a nonlinear sliding surface whose parameters change continuously with time is designed. Actually, the proposed SMC has the ability to reduce the settling time without an overshoot by giving a low damping ratio at the initial time and a high damping ratio as the output reaches the desired setpoint. At the same time, it enables a fast convergence in finite time and eliminates the singularity problem with the upper bound of an uncertain term, which cannot be measured in practice, by using a simple adaptation law. To improve the efficiency of a system in the constant torque region, the control system incorporates the maximum torque per ampere (MTPA) algorithm. The stability of the nonlinear sliding surface is guaranteed by Lyapunov stability theory. Moreover, a simple sliding mode observer is used to estimate the load torque and system uncertainties. The effectiveness of the proposed nonlinear SMC scheme is verified using comparative experimental results of the linear SMC scheme when the speed reference and load torque change under system uncertainties. From these experimental results, the proposed nonlinear SMC method reveals a faster transient response, smaller steady-state speed error, and less sensitivity to system uncertainties than the linear SMC method.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.6
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• pp.247-252
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• 2015

As software has gotten bigger in magnitude and the complexity of software has been increased, the maintenance has gained in-creasing attention for its significant impact on the cost. Identifiers have an impact on more than 90 percent of the readability which accounts for a majority portion of the maintenance activities. For this reason, the existing works focus on domain-specific features based on identifiers. However, their approaches have a limitation when either a class name does not reflect the intention of its context or a class naming is incorrect. Therefore, this paper suggests a series of class name validation process by extracting properties of classes, building learning model by applying a decision tree technique of machine learning, and generating a validation report containing the list of recommendable postfixes of classes to be validated. To evaluate this, four open source projects are selected and indicators such as precision, recall, and ROC curve present the value of this work when it comes to five specific postfixes including functional information on class names.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.7
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• pp.665-671
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• 2015

The performance of fault diagnostics for a planetary gearbox depends on vibration modulation characteristics, which can vary with manufacturing & assembly tolerance, and load condition. In this paper, a fault diagnostics technique that considers vibration modulation characteristics is proposed for the effective fault detection of planetary gearboxes in wind turbines. For identifying the vibration modulation characteristics in practice, re-sampled vibration signals are processed with narrow band-pass filters. Thereafter, the optimal position of the vibration extraction window is identified for effective detection of faulty signals under the varying vibration modulation characteristics. The proposed diagnostics technique makes it possible to perform robust diagnostics of the planetary gearbox with regard to the changeable vibration modulation effect. For demonstrating the proposed fault diagnostics technique, a 2-kW WT testbed is designed with two DC motors and gearboxes. A faulty gear with partial tooth breakage is machined and assembled into the gearbox.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.5
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• pp.503-512
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• 2014

People would like to be socially engaged not only with humans but also with robots. One of the most common ways in the robotic field to enhance human robot interaction is to use emotion and integrate emotional concepts into robots. Many researchers have been focusing on developing a robot's emotional expressions. However, it is first necessary to establish the psychological background of a robot's emotion generation model in order to implement the whole process of a robot's emotional behavior. Therefore, this article suggests a robot's motivational emotion model with value effectiveness from a Higgins' motivation definition, regulatory focus theory, and Circumplex model. For the test, a game with the best-two-out-of-three rule is introduced. Each step of the game was evaluated by the proposed model. As the results imply, the proposed model generated psychologically appropriate emotions for a robot in the given situation. The empirical survey remains for future work to prove that this research improves social human robot interaction.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.2
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• pp.124-129
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• 2013

Hexapod walking robots are superior to biped or quadruped ones in terms of walking stability. Therefore hexapod robots have the advantage in performing intelligent tasks based on walking stability. In this paper, we propose a hexapod robot that has one fore leg, one hind leg, two left legs, and two right legs and can perform various intelligent tasks. We build the robot by using 26 motors and implement a controller which consists of a host PC, a DSP main controller, an AVR auxiliary controller, and smart phone/pad. We show by several experiments that the implemented robot can perform various intelligent tasks such as uneven surface walking, tracking and kicking a ball, remote control and 3D monitoring by using data obtained from stereo camera, infrared sensors, ultra sound sensors, and contact sensors.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.1
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• pp.45-55
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• 2013

With the recent advancement of control method and battery technology, the electric vehicle have been researched to replace the conventional vehicle with electric vehicle with the view point of the environmental concerns and energy conservation. An electric vehicle which is equipped with the independent front steering system and in-wheel motors has advantage in terms of control. For example, the different torque which generated by left and right wheels directly can make yaw moment and the independent steering using outer wheel control is able to reduce the sideslip angle. Using of independent steering and driving system, the 4 wheel electric vehicle can improve a performance better than conventional vehicle. In this paper, we consider the method for improving the cornering performance of independent front steering system and in-wheel motor used electric vehicle with the compensated outer wheel angle and direct yaw moment control. Simulation results show that the method can improve the cornering performance of 4 wheel electric vehicle. We also apply the steering motor failure to steer the vehicle turned by the torque difference without steering. This paper describes an independent front steering and driving, consist of three parts; Vehicle Model, Control Algorithm for independent steering and driving and simulation. First, vehicle model is application of TruckSim software for independent front steering and 4 wheel driving. Second, control algorithm describes the reduced sideslip and direct yaw moment method in view of cornering performance. Last is simulation and verification.

• International Journal of Fluid Machinery and Systems
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• v.4 no.4
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• pp.367-374
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• 2011

Water hammer pumps can effectively use the water hammer phenomenon in long-distance pipeline networks that include pumps and allow fluid transport without drive sources, such as electric motors. The results of experiments that examined the effect of the geometric form of water hammer pumps by considering their major dimensions have been reported. In addition, a paper has also been published analyzing the water hammer phenomenon numerically by using the characteristic curve method for comparison with experimental results. However, these conventional studies have not fully evaluated the pump performance in terms of pump head and flow rate, common measures indicating the performance of pumps. Therefore, as a first stage for the understanding of water hammer pump performance in comparison with the characteristics of typical turbo pumps, the previous paper experimentally examined how the hydrodynamic characteristics were affected by the inner diameter ratio of the drive and lifting pipes, the form of the air chamber, and the angle of the drive pipe. To understand the behavior of the components attached to the valve chamber and the air chamber that affects the performance of water hammer pumps, the previous study also determined the relationship between the water hammer pump performance and temporal changes in valve chamber and air chamber pressures according to the air chamber capacity. For the geometry of components attached to the drain valve, which is another major component of water hammer pumps, this study experimentally examines how the water hammer pump performance is affected by the length of the spring and the angle of the drain pipe.