• 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 the Korea Society of Computer and Information
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• v.20 no.3
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• pp.107-113
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• 2015

This paper presents a polynomial time algorithm to the minimum cardinality feedback edge set and minimum weight feedback edge set problems. The algorithm makes use of the property wherein the sum of the minimum spanning tree edge set and the minimum feedback edge set equals a given graph's edge set. In other words, the minimum feedback edge set is inherently a complementary set of the former. The proposed algorithm, in pursuit of the optimal solution, modifies the minimum spanning tree finding Kruskal's algorithm so as to arrange the weight of edges in a descending order and to assign cycle-deficient edges to the maximum spanning tree edge set MXST and cycle-containing edges to the feedback edge set FES. This algorithm runs with linear time complexity, whose execution time corresponds to the number of edges of the graph. When extensively tested on various undirected graphs both with and without the weighed edge, the proposed algorithm has obtained the optimal solutions with 100% success and accuracy.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.4
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• pp.619-629
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• 2013

This study was conducted to compare the effect improving balance abilities of 3 balance training programs by randomized intervention trial. Study subjects were 29 female students recruited from a university in Gwanju, who allocated randomly to 3 intervention groups, aqua group(modified Halliwick 10 point program, N=10), visual bio-feedback balance training group(N=10), and balance-pad plus trampolin group(N=9). As the results of repeated musure ANOVA, Wilcoxon signed rank test, major research findings were as follows; 1. Regarding SI or BIEMG measured at upright posture on hard platform, bio-feedback group under the condition with opening both eye and aqua group under the condition with closing both eye showed signigicant improvement in balance ability, respectively. 2. Regarding SI or BIEMG measured at upright posture on soft platform, bio-feedback group under the condition with opening both eye and aqua group under the condition with closing both eye showed signigicant improvement in balance ability, respectively. 3. Regarding all 3 sensory ratios, bio-feedback group showed significantly higher increasement in them than other 2 groups. The results suggested that visual bio-feedback training program improve the all 3 sensory functions required for balancing, and aqua training modified from Halliwick 10 point program contribute to improve vestibular function principally.

• The Journal of Korean Physical Therapy
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• v.27 no.6
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• pp.407-412
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• 2015

Purpose: This study aimed to evaluate changes in the balance ability of patients whose head positions were altered due to stroke. Subjects were divided into three groups to determine the effects of the training on dynamic balance and gait. Methods: Forty-two stroke patients were enrolled. The Visual Feedback Training (VFT) group performed four sets of exercises per training session using a Sensoneck device, while the Active Range of Motion (ART) group performed eight sets per training session after receiving education from an experienced therapist. The Visual Feedback with Active Range of Motion (VAT) group performed four sets of active range of motion and two sets of visual-feedback training per session using a Sensoneck device. The training sessions were conducted three days a week for eight weeks. Results: The comparison of changes in dynamic balance ability showed that a significant difference in the total distance of the body center was found in the VFT group (p<0.05) and Significant differences were found according to the training period (p<0.05). The comparison of the 10 m walk test showed that the main effect test, treatment period and interactions between group had statistically significant differences between the three groups (p<0.05). Conclusion: Head-adjustment training using visual feedback can improve the balance ability and gait of stroke patients. These results show that coordination training between the eyes and head with visual feedback exercises can be used as a treatment approach to affect postural control through various activities involving the central nervous system.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.1109-1113
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• 2009

Exchange of data between users and system is made by users' inputting their information into HTML input forms like when signing up in websites or buying in online shopping malls. If users make a mistake of inputting their information, the system gives an error message in order for users to correct their mistakes. Although ISO recommends immediate feedback, Bargas et al. gave a report that feedback in all after filling forms out is more usable than feedback one by one when inputting data online. We made a comparative experiment on usability under each case of feedback one by one and feedback in all. The result is immediate feedback is more usable and satisfactory. The analysis of data resulted that immediate feedback produced fewer error and gets higher subjective ratings.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.4
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• pp.545-558
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• 2020

The gaze-based input provides feedback to confirm that the typing is correct when the user types the text. Many studies have already demonstrated that feedback can increase the usability of gaze-based inputs. However, because the information of the typed text is revealed through feedback, it can be a target for shoulder-surfing attacks. Appropriate feedback needs to be used to improve security without compromising the usability of the gaze-based input using the original feedback. In this paper, we propose a new gaze-based input method, FFI(Fake Flickering Interface), to resist shoulder-surfing attacks. Through experiments and questionnaires, we evaluated the usability and security of the FFI compared to the gaze-based input using the original feedback.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.6
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• pp.554-562
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• 2002

This paper presents a new sensorless control scheme using simple duty signal feedback technique in DC/DC converters. The proposed Duty Feedback Control(DFC) has the characteristics that they show the same as operation performance of current mode control by using duty feedback technique without current sensor as well as present faster dynamic response performance than conventional Sensorless Current Mode(SCM) control in case that input source is perturbed by step change or DC input source includes the harmonics. Also, the proposed control scheme has good noise immunity and simple control circuits since they have one feedback loop, and can be applied to all DC/DC converters. The concept and control principles of the proposed control scheme are explained in detail and the validity of the proposed control scheme is verified through several interesting simulated and experimental results.

• The KIPS Transactions:PartB
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• v.13B no.4 s.107
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• pp.383-392
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• 2006

In this paper, we propose a new relevance feedback algorithm using Probabilistic Neural Networks(PNN) while supporting multi-class learning. Then, to validate the effectiveness of our feedback approach, we incorporate the proposed algorithm into our region-based image retrieval tool, FRIP(Finding Regions In the Pictures). In our feedback approach, there is no need to assume that feature vectors are independent, and as well as it allows the system to insert additional classes for detail classification. In addition, it does not have a long computation time for training because it only has four layers. In the PNN classification process, we store the user's entire past feedback actions as a history in order to improve performance for future iterations. By using a history, our approach can capture the user's subjective intension more precisely and prevent retrieval performance errors which originate from fluctuating or degrading in the next iteration. The efficacy of our method is validated using a set of 3000 images derived from a Corel-photo CD.

• Journal of Broadcast Engineering
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• v.14 no.2
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• pp.107-113
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• 2009

In Digital On-Channel Repeaters (DOCR) of Terrestrial-DMB (Digital Multimedia Broadcasting), there exist feedback signals generated from transmit antenna and re-entering at receive antenna. Therefore DOCR becomes unstable unless the feedback signal is properly eliminated. Previous research proposed a feedback canceller to estimate the feedback channel to deal with this problem. However formerly used estimation algorithms show unsatisfied performance in terms of convergence rate and quality although their implementations are simple. This paper applies PNLMS (Proportionate Normalized Least Mean Squares) adaptive algorithm to feedback channel estimation and evaluates the performances which solve the problem of feedback signal effectively.

• The Journal of the Korea Contents Association
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• v.7 no.2
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• pp.150-160
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• 2007

In the actual classroom the so-called flow learning is able to motivate the students through face-to-face feedback, and to meet their needs for educational achievement. By contrast, the so-called e-learning method falls short of the satisfactory level of real-life interaction, which makes many learners drop out or give up on their learning. In order to better the e-learning environment, this study presents a dialogue-based feedback system that improves the flow learning of the learners' in the classroom. This newly developed system was applied at the actual school. The result is that the experimented group improved its flow learning, compared with the controlled group. In the former group, each individual showed some consciousness of objective and challenge following the concrete feedback. That is to say, this system enhances the attitude of an active participation and induces the flow learning, thanks to the dialogue-based feedback and the sustained interest in learning. In conclusion, the significance of this study lies in suggesting the direction of a new learning method development in the e-learning environment.