• International Journal of Aeronautical and Space Sciences
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• v.12 no.2
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• pp.163-174
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• 2011

Task assignments of multiple unmanned aerial vehicles (UAVs) are examined. The phrase "task assignment" comprises the decision making procedures of a UAV group. In this study, an on-line decentralized task assignment algorithm is proposed for an autonomous UAV group. The proposed method is divided into two stages: an order optimization stage and a communications and negotiation stage. A genetic algorithm and negotiation strategy based on one-to-one communication is adopted for each stage. Through the proposed algorithm, decentralized task assignments can be applied to dynamic environments in which sensing range and communication are limited. The performance of the proposed algorithm is verified by performing numerical simulations.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.10
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• pp.855-868
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• 2004

There are several types of singularities in controlling robotic manipulators: kinematic singularity, algorithmic singularity, semi-kinematic singularity, semi-algorithmic singularity, and representation singularity. The kinematic and algorithmic singularities have been investigated intensively because they are not predictable or difficult to avoid. The problem with these singularities is an unnecessary performance reduction in non-singular region and the difficulty in performance tuning. Tn this paper, we propose a method of avoiding kinematic and algorithmic singularities by applying a task reconstruction approach while maximizing the task performance by calculating singularity measures. The proposed method is implemented by removing the component approaching the singularity calculated by using singularity measure in real time. The outstanding feature of the proposed task reconstruction method (TR-method) is that it is based on a local task reconstruction as opposed to the local joint reconstruction of many other approaches. And, this method has dynamic task priority assignment feature which ensures the system stability under singular regions owing to the change of task priority. The TR-method enables us to increase the task controller gain to improve the task performance whereas this increase can destabilize the system for the conventional algorithms in real experiments. In addition, the physical meaning of tuning parameters is very straightforward. Hence, we can maximize task performance even near the singular region while simultaneously obtaining the singularity-free motion. The advantage of the proposed method is experimentally tested by using the 7-dof spatial manipulator, and the result shows that the new method improves the performance several times over the existing algorithms.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.3
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• pp.267-274
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• 2014

The purpose of this study is to identify a relationship between the time taken and the characteristics of touch key for touch-screen-based in-vehicle information system (IVIS) and to suggest a new Fitts' law formula that is added a driving speed parameter. Many studies already have shown that Fitts' law is well fitted in various devices for primary tasks, but there is no study of Fitts' law for secondary task in dual-task situation. Fitts' law may not be applied to the secondary task as it is, because the secondary task performance can be affected by the amount of attention for the primary task. To verify this, we carried out an experiment that showed whether pointing task to touch-screen-based IVIS during driving is affected by driving speeds or not. In the experiment, 30 people were volunteered for participants and the participants carried out driving task and pointing task on the screen of IVIS simultaneously. We measured the time to point a touch key on IVIS for every condition (3 driving speeds${\times}5$ touch key sizes${\times}7$ distances between steering wheel and touch key). As a result, there was an effect of driving speed on the pointing time. As we extended the index of difficulty of the conventional Fitts' law formula by incorporating driving speed, we established an extended Fitts' law formula for pointing on IVIS, which showed better accordance with dual task situation. This study can be evidence that secondary task performance is affected by degree of concentration on primary task, and the extended Fitts' law formula can be useful to design interfaces of IVIS.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.4
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• pp.83-91
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• 2022

Purpose: The goal of this study was to investigate changes in dual-task performance according to age and difficulty of cognitive tasks for the in community-dwelling elderly populations, as well as to examine their changes in hand dexterity according to age and cognitive function. Methods: A total of 135 people aged 65 years old and over participated in the study. To evaluate each participant's dual-task performance, each participant completed a dual task. To assess their cognitive function, the Korean Mini-Mental State Examination (MMSE-K) and the Korean version of Montreal Cognitive Assessment (MoCA-K) were the tools used. Participants were divided into three groups based on their age: 65-69 years, 70-79 years, and 80-89 years. Results: The findings showed that age groups and the difficulty of the cognitive task significantly affected the amount of time required for dual-task performance (p<.001). Additionally, the dual-task correct response rate (CRR) decreased significantly with age groups and the difficulty of the cognitive task (p<.001). The amount of time required for finger dexterity performance increased significantly with age groups (mean score±standard deviation [SD]; 19.46±2.26 in subjects aged 65-69 years; 21.92±2.61 in subjects aged 70-79 years; and 23.82±2.92 in subjects aged 80-89 years; p<.001). Moreover, as a result of the correlation between hand dexterity and cognitive function, MoCA-K was -0.563 and MMSE-K was -.412, showing a statistically significant correlation (p<.001). Conclusions: Age and the difficulty of the cognitive task affect the community-dwelling elderly populations in terms of dual-task performance and dual-task CRR. In addition, aging and general cognition have an impact on hand dexterity. Based on the results of this study, it is anticipated that the results will serve as a reference for domestic clinical trials that confirm cognitive decline in the elderly using dual task and hand dexterity evaluation.

• Journal of Korean Academy of Nursing
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• v.36 no.5
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• pp.770-781
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• 2006

Purpose: This study was designed to create a job description for Korean geriatric care managers and examine performance frequency, importance, and difficulty of task elements. Method: The sample consisted of 38 geriatric care managers and professors who performed duties related to geriatric care management at community based-facilities in Korea. A survey method was used, and the questionnaire included frequency, importance, and difficulty of task elements in job descriptions using the DACUM method. Using SPSS WIN 10.0, descriptive statistics such as frequency distribution, means, and standard deviation were conducted to examine the subject's general characteristics, frequency, importance, and difficulties of task performance. Result: The Job description of geriatric care managers revealed 10 duties, 34 tasks, and 105 task elements. On all ten duties, the average performance frequency, importance, and difficulty was 2.55, 2.21 and 2.43 respectively. Conclusion: The job description of geriatric care managers includes duty, task, and task elements and the definition of a completed job. Thus we recommend a data based trial to confirm and validate the information gathered.

• Journal of the Korean Society of Physical Medicine
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• v.8 no.2
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• pp.175-182
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• 2013

PURPOSE: The purpose of this study was to investigate the effects of task oriented ADL exercise in different environments in patients with chronic stroke. METHODS: A total of 28 patients with hemiplegia resulting from stroke were included in this study. The patients were randomized into two groups. The control group(n=14) was received neurodevelopment therapy + task oriented ADL exercise and experimental group(n=14) was received neurodevelopment therapy + home based task oriented ADL exercise for 30 minutes twice per week during 6weeks. A task oriented ADL exercise pretest and postest design was used examine the change of FIM(Functional Independent Measure) and K-MBI(Korea-Modified Bathel Index) at the completion of 6 weeks task oriented ADL exercise. RESULTS: After 6 weeks, the experimental group compared with control group showed a significant improvement (p<.05) in FIM and K-MBI scores. CONCLUSION: The results indicate that the home based task oriented ADL exercise improves functions in the persons with chronic stroke.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.895-901
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• 1993

This paper present controller designs based on the configuration control framework for a redundant manipulator to accomplish the basic task of desired, end-effector motion, while utilizing the redundancy to achieve the additional tasks such as joint motion control, obstacle avoidance, singularity avoidance. etc. A task based decentralized adaptive scheme is then applied for the configuration variables to track some reference trajectories as close as possible. Simulation results for a direct-drive three-link arm in the vertical plane demonstrate its capabilities for performing various useful tasks.

• Journal of the Korean Society of Safety
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• v.24 no.3
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• pp.71-78
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• 2009

During a learning process, a human being is assumed to experience knowledge-based behaviors, rule-based behaviors, and skill-based behaviors sequentially if Rasmussen was right. If any psycho-physiological symptom to those different levels can be obtained, it can be useful as a measure whether a human being is fully trained and has gotten a skill in his work. Therefore, this study aimed to draw relationships between human performance measures and psycho-physiological measures while committing a computer-simulated pointing task by utilizing the power spectrum technique of EEG data, especially with the ratio of relative beta-to-alpha band power. The result showed that, during correct responses, the ratio came to stabilize as all the performance data went stable. However, response time was not a simple linear function of task difficulty level only, but a joint function of task characteristics as well as behavior levels. Comparing relative band power ratios from errors and correct responses, activated states of one's brain could be explained, and characteristics of the task could understood. To tell that of pointing task, correlations around C3, C4, P3, P4 and 01, 02 area were significant and high in correct response cases whereas most correlation coefficients went down in error cases standing for imbalance of psycho-motor functions. Though task difficulty was the only one factor that could influence on relative band power ratio with statistical significance, it should be comprehended to mean a different way of expression indicating task characteristics since at least error-some situation could be explained with the help of relative band power ratio that absolute band power failed.

• The Journal of Information Systems
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• v.29 no.4
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• pp.77-99
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• 2020

Purpose The purpose of this study is to investigate the effect of two-way communication and knowledge sharing on the task performance of employees in the interdependent task structure in organizations. Based on the theories of social interdependence and organizational commitment, this study hypothesized the effects of task interdependency and emotional commitment on two-way communication and knowledge sharing, followed by the effects of these variables on the task performance of employees. Design/methodology/approach Survey results show that task interdependence and emotional commitment have positive effects on the degree of two-way communication and knowledge sharing. Two-way communication also has a positive impact on knowledge sharing, and knowledge sharing also improved the task performance of members. However, the relationship between two-way communication and task performance shows no significant impact. Findings Theoretically, this study is meaningful in that the process of task interdependence in relation to emotional commitment leading to task performance is theorized. In practice, this research suggests it is important to improve employees' two-way communication and knowledge sharing in order to lead to increase task performance in the interdependent task environment.

• Speech Sciences
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• v.10 no.3
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• pp.37-45
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• 2003

This study attempted to determine the effects of a context-based drawing task on the language expression of a severe Wernicke's and Broca's aphasic. The subjects in this study showed a poor auditory comprehension and naming performance. They also showed paraphasia and perseveration. This study focused on improving language expression by a drawing task based on conversation at hand. Ten target words were chosen which were easily drawnable and familiar to the subjects. The results showed that the context-based drawing task was effective on improving the subjects' confrontation naming ability and expressive language ability in terms of explanation of sentences. In addition, the Broca's aphasic showed improved naming ability when the contextual cues were given and he was supposed to spontaneously name words.