• Physical Therapy Korea
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• v.11 no.3
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• pp.11-18
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• 2004

This study is aimed at investigating the influence of different quantitative knowledge of results on the measurement error during lumbar proprioceptive sensation training. Twenty-eight healthy adult men participated and subjects were randomly assigned into four different feedback groups(100% relative frequency with an angle feedback, 50% relative frequency with an angle feedback, 100% relative frequency with a length feedback, 50% relative frequency with a length feedback). An electrogoniometer was used to determine performance error in an angle, and the Schober test with measurement tape was used to determine performance error in a length. Each subject was asked to maintain an upright position with both eyes closed and both upper limbs stabilized on their pelvis. Lumbar vertebrae flexion was maintained at $30^{\circ}$ for three seconds. Different verbal knowledge of results was provided in four groups. After lumbar flexion was performed, knowledge of results was offered immediately. The resting period between the sessions per block was five seconds. Training consisted of 6 blocks, 10 sessions per one block, with a resting period of one minute. A resting period of five minutes was provided between 3 blocks and 4 blocks. A retention test was performed between 10 minutes and 24 hours later following the training block without providing knowledge of results. To determine the training effects, a two-way analysis of variance and a one-way analysis of variance were used with SPSS Ver. 10.0. A level of significance was set at .05. A significant block effect was shown for the acquisition phase (p<.05), and a significant feedback effect was shown in the immediate retention phase (p>.05). There was a significant feedback effect in the delayed retention phase (p<.05), and a significant block effect in the first acquisition phase and the last retention phase (p<.05). In conclusion, it is determined that a 50% relative frequency with a length feedback is the most efficient feedback among different feedback types.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.6
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• pp.275-284
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• 2023

Virtual reality simulations are used for education and training in various fields, and are especially widely used in the medical field recently. The education/training simulator consists of tactile/force feedback generation and image/sound output hardware that provides a sense similar to a doctor's treatment of a real patient using real surgical tools, and software that produces realistic images and tactile feedback. Existing simulators are complicated and expensive because they have to use various types of hardware to simulate various surgical instruments used during surgery. In this paper, we propose a dental surgical simulation system using a force feedback device and a morphable haptic controller. Haptic hardware determines whether the surgical tool collides with the surgical site and provides a sense of resistance and vibration. In particular, haptic controllers that can be deformed, such as length changes and bending, can express various senses felt depending on the shape of various surgical tools. When the user manipulates the haptic feedback device, events such as movement of the haptic feedback device or button clicks are delivered to the simulation system, resulting in interaction between dental surgical tools and oral internal models, and thus haptic feedback is delivered to the haptic feedback device. Using these basic techniques, we provide a realistic training experience of impacted wisdom tooth extraction surgery, a representative dental surgery technique, in a virtual environment represented by sophisticated three-dimensional models.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.5
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• pp.211-219
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• 2010

There are significant changes are in education field: the paradigm shift from teacher-centered and text-oriented learning to learner-centered and multimedia-oriented learning. Many researchers have proposed that the e-learning contents is one of the most important factors on e-learning performance. This study analyzes the effect of types of test information on learning performance in e-learning contents. The results show that the interaction effect between types and gender influences the comprehension of learning; the female prefers to the feedback and narrative type but the male prefer to the narrative type. The narrative type showed the highest score on the comprehension and satisfaction of learning among three different types. Also, the main effect of gender difference had no effect on e-learning performance.

• The Journal of Korean Physical Therapy
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• v.27 no.2
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• pp.81-84
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• 2015

Purpose: The purpose of this study was to compare the effect of 'knowledge of result' and 'knowledge of performance', two types of extrinsic feedbacks, during the sit-to-stand movement in children with hemiplegic cerebral palsy. Methods: A total of ten children with hemiplegic cerebral palsy (ages 8 to 12 years) were recruited for the study. Subjects with hemiplegic cerebral palsy performed sit-to-stand movement in front of a mirror. Their performance was supervised and revised for normal movement by a pediatric physiotherapist. In the knowledge of the result, subjects performed sit-to-stand using a chair with an armrest in their mind with normal movement. In the knowledge of performance, subjects performed sit-to-stand under verbal instructions. Randomized cross over trials were used in this study. Main outcome measurements were as follows: mediolateral speed, anteroposterior speed, velocity moment, extent in mediolateral direction, extent in anteroposterior direction, and vertical distance of the center of pressure. Results: The mediolateral speed and extent of center of pressure was higher for 'knowledge of performance' in comparison with the other type of extrinsic feedbacks (p<0.05). The other parameters, including anteroposterior speed and extent, and vertical speed of the center of pressure, did not differ between the two types of extrinsic feedbacks (p>0.05). Conclusion: These findings suggested that training in sit-to-stand movement with 'knowledge of result' may result in better use of extrinsic feedback.

• Journal of Information Technology Applications and Management
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• v.9 no.2
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• pp.17-32
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• 2002

Even though the distance education via web has a great advantage to overcome time and space, its problem is that the management of trainees is not efficient compared with classroom and group education. This problem is a great obstacle to the objects and achievement standards of distance education, giving controversial arguments to the advocators of distance education. Distance educators need to monitor the trainees'participation and responses continuously and offer appropriate feedback to the trainees. However, the existing distance education system only focuses on teaching and learning activities, and as a result, the efficient management function of distance education is not available. Accordingly, the study attempts to find out the appropriate managing elements of distance teacher training in order to effectively achieve the goals of teacher training and the efficient management of distance education. Also, it proposes distance teacher training management system that offers appropriate feedback to trainees, applying the derived elements of distance teacher training to the training processes. To verify the efficiency of the system, hypotheses on related items of distance teacher education and learning types are suggested, and the achievement degree of learning and its relations are investigated through questionnaire of learning types. In addition, a system using UML which is the standard of object-oriented modeling language is devised, so. that mutual management, language independence and convenient development environment as well as reusability can be offered, and so the design standardization and efficient system realization could be achieved, while flexible change of system according to education process and computing environment is possible.

• Journal of Power Electronics
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• v.13 no.3
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• pp.447-457
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• 2013

For grid-connected LCL-filtered inverters, resonance yields instability and low bandwidth. As a result, careful designs are required. This paper presents a systematic current control structure, where pole assignment consisting of one or more feedbacks is the inner loop, and the outer loop is the direct grid current control. Several other issues are discussed, such as the inner-loop feedback choices, pole-assignment algorithms, robustness and harmonic rejection. Generally, this kind of strategy has three different types according to the inner-loop feedback choices. Among them, a novel pole-assignment algorithm has been proposed, where the inner control maintains four freely-assigned poles which are just two pairs of conjugated poles located at the fundamental and resonance frequencies separately. It has been found that with the different types, the steady-state and dynamic performances are quite different. Finally, simulations and experiments have been provided to verify the control and design of the proposed methods.

• The Journal of the Korea Contents Association
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• v.17 no.3
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• pp.359-369
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• 2017

The purpose of this study was to examine whether the effect of feedback would mask the performance differences that would result from different incentive pay distribution. Five critical service behaviors were identified and measured daily at a gas station located in Seoul. Participants were 5 employees working at the gas station. Independent variables were the types of incentive distribution and feedback. After baseline (A), equally-distributed group incentive condition (B) was introduced, and individual incentive condition (C) was introduced in the next phase. Then, after the withdrawal condition (A'), equally-distributed group incentive with feedback condition (B') was introduced and finally, the individual incentive with feedback condition (C') was introduced. The results suggested that all employees showed higher work performance under individual incentive than equally-distributed group incentive system when feedback were not delivered. However, there was no difference in work performance between two incentive conditions in the phases in which feedback were delivered. These findings suggest that feedback can reduce performance differences between equally-distributed group incentives and individual incentives.

• Korean Journal of Cognitive Science
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• v.28 no.1
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• pp.65-90
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• 2017

Rewards or penalties become informative only when contingent on an immediately preceding response. Our goal was to determine if the brain responds differently to motivational events depending on whether they provide feedback with the contingencies effective for learning. Event-related fMRI data were obtained from 22 volunteers performing a visuomotor categorical task. In learning-condition trials, participants learned by trial and error to make left or right responses to letter cues (16 consonants). Monetary rewards (+500) or penalties (-500) were given as feedback (learning feedback). In random-condition trials, cues (4 vowels) appeared right or left of the display center, and participants were instructed to respond with the appropriate hand. However, rewards or penalties (random feedback) were given randomly (50/50%) regardless of the correctness of response. Feedback-associated BOLD responses were analyzed with ANOVA [trial type (learning vs. random) x feedback type (reward vs. penalty)] using SPM8 (voxel-wise FWE p < .001). The right caudate nucleus and right cerebellum showed activation, whereas the left parahippocampus and other regions as the default mode network showed deactivation, both greater for learning trials than random trials. Activations associated with reward feedback did not differ between the two trial types for any brain region. For penalty, both learning-penalty and random-penalty enhanced activity in the left insular cortex, but not the right. The left insula, however, as well as the left dorsolateral prefrontal cortex and dorsomedial prefrontal cortex/dorsal anterior cingulate cortex, showed much greater responses for learning-penalty than for random-penalty. These findings suggest that learning-penalty plays a critical role in learning, unlike rewards or random-penalty, probably not only due to its evoking of aversive emotional responses, but also because of error-detection processing, either of which might lead to changes in planning or strategy.

• Molecules and Cells
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• v.27 no.5
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• pp.497-502
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• 2009

In mouse embryos, somite formation occurs every two hours, and this periodic event is regulated by a biological clock called the segmentation clock, which involves cyclic expression of the basic helix-loop-helix gene Hes7. Hes7 expression oscillates by negative feedback and is cooperatively regulated by Fgf and Notch signaling. Both loss of expression and sustained expression of Hes7 result in severe somite fusion, suggesting that Hes7 oscillation is required for proper somite segmentation. Expression of a related gene, Hes1, also oscillates by negative feedback with a period of about two hours in many cell types such as neural progenitor cells. Hes1 is required for maintenance of neural progenitor cells, but persistent Hes1 expression inhibits proliferation and differentiation of these cells, suggesting that Hes1 oscillation is required for their proper activities. Hes1 oscillation regulates cyclic expression of the proneural gene Neurogenin2 (Ngn2) and the Notch ligand Delta1, which in turn lead to maintenance of neural progenitor cells by mutual activation of Notch signaling. Taken together, these results suggest that oscillatory expression with short periods (ultradian oscillation) plays an important role in many biological events.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.100-104
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• 1993

In Part 1, we derived robust stability conditions for an LTI interconnected to time-varying nonlinear perturbations belonging to several classes of nonlinearities. These conditions were presented in terms of positive definite solutions to LMI. In this paper we address a problem of synthesizing feedback controllers for linear time-invariant systems under structured time-varying uncertainties, combined with a worst-case H$_{2}$ performance. This problem is introduced in [7, 8, 15, 35] in case of time-invariant uncertainties, where the necessary conditions involve highly coupled linear and nonlinear matrix equations. Such coupled equations are in general difficult to solve. A convex optimization approach will be employed in this synthesis problem in order to avoid solving highly coupled nonlinear matrix equations that commonly arises in multiobjective synthesis problem. Using LMI formulation, this convex optimization problem can in turn be cast as generalized eigenvalue minimization problem, where an attractive algorithm based on the method of centers has been recently introduced to find its solution [30, 361. In the present paper we will restrict our discussion to state feedback case with Popov multipliers. A more general case of output feedback and other types of multipliers will be addressed in a future paper.