• The Journal of Korean Physical Therapy
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• v.28 no.1
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• pp.14-21
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• 2016

Purpose: The purpose of this study was to investigate examine how the kinematics and kinetics of lower limb joints were changed depending on the unstable shoes (US) during sit-to-stand task (SitTS). Methods: Nineteen healthy females were participated in this study. The subjects performed sit-to-stand task with US and barefoot. The experiment was repeated three times for each tasks with conditions. The kinematics and kinetics of lower limb joint were measured and analyzed using a 3-D motion analysis system. A paired t-test was utilised performed for to identificationy of changes in mean of angle, force, and moment between both the two conditions. Results: The results of this study showed kinematic differences in lower limb joints during SitTS based on the US. The hip, knee, and ankle angle showed statistically significant differences during SitTS. At the initial of SitTS, Tthe force and moment of the hip flexor, hip extensor, knee flexor, knee extensor, ankle flexor, and ankle extensor showed statistically significant differences. At the terminal of SitTS, Tthe force and moment of the hip flexor, hip extensor, knee flexor, knee extensor, ankle flexor, and ankle extensor showed statistically significant differences. At the maximum of SitTS, Tthe moment of the hip extensor showed statistically significant differences. The force and moment of the ankle flexor, extensor moment showed statistically significant differences. Conclusion: Therefore, Wwearing US is considered to influence on the lower limb joints kinematics and kinetics during SitTS movements, and thus suggests the possibility that of reducing the risks of pain, and osteoarthritis caused by changes in the loading of lower limb joints.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.208-222
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• 2021

Managing with the presence of sea ice is the primary challenge in the operation of floating platforms in the Arctic region. It is widely accepted that offshore structures operating in Arctic conditions need station-keeping methods as well as ice management by icebreakers. Dynamic Positioning (DP) is one of the station-keeping methods that can provide mobility and flexibility in marine operations. The presence of sea ice generates complex external forces and moments acting on the vessel, which need to be counteracted by the DP system. In this paper, an icevaning control algorithm is proposed that enables Arctic offshore vessels to perform DP operations. The proposed icevaning control enables each vessel to be oriented toward the direction of the mean environmental force induced by ice drifting so as to improve the operational safety and reduce the overall thruster power consumption by having minimum external disturbances naturally. A mathematical model of an Arctic offshore vessel is summarized for the development of the new icevaning control algorithm. To determine the icevaning action of the Arctic offshore vessel without any measurements and estimation of ice conditions including ice drift, task and null space are defined in the vessel model, and the control law is formulated in the task space. A backstepping technique is utilized to handle the nonlinearity of the Arctic offshore vessel's dynamic model, and the Lyapunov stability theory is applied to guarantee the stability of the proposed icevaning control algorithm. Experiments are conducted in the ice tank of the Korea Research Institute of Ships and Ocean Engineering to demonstrate the feasibility of the proposed approach.

• Journal of KIISE:Information Networking
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• v.31 no.1
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• pp.70-80
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• 2004

In order to reduce the increasing packet loss rates caused by an exponential increase in network traffic, the IETF(Internet Engineering Task Force) is considering the deployment of active queue management techniques such as RED(Random Early Detection). But, RED configuration has been a problem since its first proposal. This problem is that proposed configuration is only good for the particular traffic conditions studied, but may have detrimental effects if used in other conditions. While active queue management in routers and gateways can potentially reduce packet loss rates in the Internet, this paper has demonstrated the inherent weakness of current techniques and shows that they are unstable for tile various traffic conditions. The inherent problem with these queue management algorithms is that they all use static parameter setting. In this paper, in order to solve this problem, a new active queue management algorithm called SQM(Stabilized Queue Management) is proposed. This paper shows that it is easy to parameterize SQM algorithm to perform well under different congestion scenarios. This algorithm can effectively reduce packet loss while maintaining high link utilizations and is good for the various traffic conditions.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.356-362
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• 2012

This study examined the effects of vocalization on upper extremity muscle activity during reaching task in patients with hemiplegia. Thirteen persons with right brain stroke performed reaching to a cup under four concurrent speech conditions of vocalizing the word "Ah" with hemiplegic side. These four conditions are self-vocalization, external vocalization, imaginary vocalization, and no vocalization. The muscle activity(Biceps brachii, Triceps brachii, Middle deltoid, and Upper trapezius) were measured using MP150. Muscle activity was significantly higher under self-vocalization and external vocalization conditions compared to the muscle activity under imaginary vocalization and no vocalization conditions on triceps brachii muscle.(p<0.05). Triceps brachii muscle was highly correlated with biceps brachii muscle(r=0.777, p<0.05). The results suggest that self-vocalization and external vocalization can be used in facilitating upper extremity movements in patients with stroke. When working with patients with right hemispheric stroke, therapists might explore possibilities of using patient's self-speech to enhance the quality of upper extremity movement performance.

• Physical Therapy Korea
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• v.19 no.3
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• pp.40-50
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• 2012

The purpose of this study was to investigate the effect of visual feedback on the postural control of stroke patients, by systematically varying conditions of visual feedback [eye-open condition (EO) vs. eye-closed condition (EC)], and base-support (both-side support, affected-side support, and unaffected-side support). In this study, we allocated 41 stroke patients with no damage in the cerebellum and visual cortex who can walk at least 10 meters independently, and 35 normal adults who have no experience of stroke to the control group. Both groups were asked to perform a "sit-to-stand" task three to five times, and their postural control ability was measured and compared in terms of asymmetric dependence (AD) instead of the traditional symmetric index (SI) in the literature. The results showed that although both subject groups maintained better postural control in the EO condition than in the EC condition, the patient group appeared to be more stable in EC than in EO when they were required to perform the task of the support condition given on the affected side. These results implied that visual feedback can impair stroke patients' postural control when it is combined with a specific support condition.

• Bulletin of the Korean Institute for Industrial Safety
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• v.3 no.1
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• pp.11-17
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• 2003

In recent years, work-related musculoskeletal disorders (WMSDs) are one of major issues in occupational safety and health in Korea, since the number of injured workers has rapidly increased and the related regulation was amended to improve the work conditions. Main risk factors of WMSDs in Korean industries include manual handling of heavy weight loads, awkward postures, repetitive tasks, prolonged static muscle contraction, and so on. in this article, some ergonomics case studies for identifying the risk factors of WMSDs and far their prevention were introduced. They include a biomechanical analysis for the heavy-weight handling task in a machine-repair shop, physiological evaluation of backpack-carrying tasks in a beverage delivery job, and a set of psychophysical studies to evaluate static-postural load. These studies showed that there are several different ergonomic approaches to identifying and evaluating risk factors of WMSDs and to eliminating them or reducing their levels, and that it is important to select proper methods and apply them in improving the work conditions according to the characteristics of the task. In addition, it needs to develop practical and effective ergonomic tools to prevent WMSDs and to provide these tools to the safety managers in the field so that they can improve the tasks by themselves.

• Therapeutic Science for Rehabilitation
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• v.10 no.1
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• pp.105-114
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• 2021

Objective : The purpose of this study was to identify and compare the sex differences in episodic memory and spatial cognition in healthy young adults. Methods : Forty-eight undergraduates (male=24, female=24) were assessed for sex differences using the visual stimuli episodic memory task and the virtual reality-based spatial cognition task. The accuracy rates (%) for the What, Where, and When conditions of the episodic memory task and the average distance error (cm) for 10 trials of the spatial cognition task were analyzed. Results : There were no significant sex differences between the three conditions. The male participants showed a significantly higher performance on the spatial cognition task than the female participants Conclusion : The results of this study indicated that the sex differences in episodic memory could be altered by the test methods. Although episodic memory and spatial cognition mainly depend on the hippocampus, the sex-related differences between the two functions were inconsistent, suggesting that these two functions are independent.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.6
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• pp.465-469
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• 2001

In injection molding short shot is one of the frequent and fatal defects. Experts of Injection molding usually adjust process conditions such as injection time, mold temperature, and melt temperature because it is most economic way in time and cost. However, it is difficult task to find appropriate process conditions for troubleshooting of short shot as injection molding process is a highly nonlinear system and process conditions are coupled. In this paper, a modular fuzzy neural network (MFNN) has been applied to injection molding process to shorten troubleshooting time of short shot. Based on melt temperature and fill time, a reasonable initial mo이 temperature is recommenced by the NFNN, and then the mold temperature is inputted to injection molding process. Depending on injection molding result, specifically the insufficient quantity of an injection molded part. and appropriate mold temperature is recommend repeatedly through the NFNN.

• International Journal of Control, Automation, and Systems
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• v.6 no.6
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• pp.904-914
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• 2008

An action-selection-mechanism(ASM) has been proposed to work as a fully connected finite state machine to deal with sequential behaviors as well as to allow a state in the task program to migrate to any state in the task, in which a primitive node in association with a state and its transitional conditions can be easily inserted/deleted. Also, such a primitive node can be learned by a shortest path-finding-based reinforcement learning technique. Specifically, we define a behavioral motivation as having state-dependent value as a primitive node for action selection, and then sequentially construct a network of behavioral motivations in such a way that the value of a parent node is allowed to flow into a child node by a releasing mechanism. A vertical path in a network represents a behavioral sequence. Here, such a tree for our proposed ASM can be newly generated and/or updated whenever a new behavior sequence is learned. To show the validity of our proposed ASM, experimental results of a mobile robot performing the task of pushing- a- box-in to- a-goal(PBIG) will be illustrated.

• Imaging Science in Dentistry
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• v.46 no.4
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• pp.245-249
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• 2016

Purpose: This study was designed to evaluate differences in the required visibility of anatomic structures according to the diagnostic tasks of implant planning and periapical diagnosis. Materials and Methods: Images of a real skull phantom were acquired under 24 combinations of different exposure conditions in a cone-beam computed tomography scanner (60, 70, 80, 90, 100, and 110 kV and 4, 6, 8, and 10 mA). Five radiologists evaluated the visibility of anatomic structures and the image quality for diagnostic tasks using a 6-point scale. results: The visibility of the periodontal ligament space showed the closest association with the ability to use an image for periapical diagnosis in both jaws. The visibility of the sinus floor and canal wall showed the closest association with the ability to use an image for implant planning. Variations in tube voltage were associated with significant differences in image quality for all diagnostic tasks. However, tube current did not show significant associations with the ability to use an image for implant planning. conclusion: The required visibility of anatomic structures varied depending on the diagnostic task. Tube voltage was a more important exposure parameter for image quality than tube current. Different settings should be used for optimization and image quality evaluation depending on the diagnostic task.