• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10A
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• pp.727-735
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• 2009

To alleviate positioning error using wireless ultra-wideband (UWB) is primary concern, and it has been studied how to reduce the positioning error effectively. Thanks to many repeated transmissions of UWB signals, we can have a variety of selections to point out the most precise positioning result. Towards this, scanning method has been preferred to be used due to its simplicity. This exhaustive method firstly fixes the candidate position, and calculates the sum of distances from observed positions. However, it has tremendous number of computations, and the complexity is more serious if the size of two-dimensional range is the larger. To mitigate the large number of computations, this paper proposes the technique employing genetic algorithm and block windowing. To exploit its superiority, simulations will be conducted to show the reduction of complexity, and the efficiency on positioning capability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1C
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• pp.59-64
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• 2004

We propose a new RLL(run length limited) (2,7) PP(parity preserving) code with 4 RMTR(repeated minimum transition run) for optical recording. The proposed code has better characteristics in terms of density ratio, RMTR, DC(direct current) component suppression, BER(bit error rate) and system complexity than (2,1O) code that currently applied in storage systems and (1,7) PP code that highly recommended as the next generation optical recording system. Some characteristics of the code are described with several simulations. And the proposed code's superiorites in performance is illustrated as compared with the other codes.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.117-122
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• 2022

This paper proposes a method for evaluating the work of manufacturing workers using MediaPipe as a risk factor for musculoskeletal diseases. Recently, musculoskeletal disorders (MSDs) caused by repeated working attitudes in industrial sites have emerged as one of the biggest problems in the industrial health field while increasing public interest. The Korea Occupational Safety and Health Agency presents tools such as NIOSH Lifting Equations (NIOSH), OWAS (Ovako Working-posture Analysis System), Rapid Upper Limb Assessment (RULA), and Rapid Entertainment Assessment (REBA) as ways to quantitatively calculate the risk of musculoskeletal diseases that can occur due to workers' repeated working attitudes. To compensate for these shortcomings, the system proposed in this study obtains the position of the joint by estimating the posture of the worker using the posture estimation learning model of MediaPipe. The position of the joint is calculated using inverse kinetics to obtain an angle and substitute it into the REBA equation to calculate the load level of the working posture. The calculated result was compared to the expert's image-based REBA evaluation result, and if there was a result with a large error, feedback was conducted with the expert again.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.10
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• pp.2100-2112
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• 2011

An orthogonal code hopping multiplexing (OCHM) technique has been proposed for accommodating a large number of users with low channel activities than the number of orthogonal codewords through statistical multiplexing in downlink cellular systems. In this paper, a multiple input multiple output (MIMO) antenna based OCHM system is proposed to improve the performance. Each modulated symbol is repeated N times and the N repeated symbols are transmitted simultaneously using N transmit antennas. Through repetitions, the effect of perforations that the OCHM system experiences is decentralized among the repeated symbols and the full perforation probability is significantly reduced. Each receiver detect the transmitted signal using its pre-assigned code hopping pattern. Simulation results show that the proposed scheme saves the required energy for a given frame error rate (FER).

• The Journal of the Korea Contents Association
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• v.21 no.5
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• pp.996-1003
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• 2021

The purpose of this study is to evaluate the reliability of repeated measurements of several dental scanners. Blue-lighted scanners, white-light scanners and optical-type scanners are used in the study of repeatability in this study. The measurement results were calculated as root mean square (RMS) and the significance level was confirmed by applying the 1-way ANOVA statistical technique (𝛼=.05). According to the statistical analysis, the scanner with the largest RMS value was Z-opt group (38.2 ㎛. Next, D-white was 35.2 ㎛ and the group with the lowest RMS value was I-blue (34.1 ㎛). The comparison of RMS means between each group was not significant (p>.05). From this result, the blue light had the lowest error in repeatability of dental scanners, but no statistical significance. The conclusion of this study is that the study results are clinically acceptable.

• Journal of Korean Physical Therapy Science
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• v.19 no.3
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• pp.57-62
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• 2012

Background and Purpose : This study was to analysis effects of muscle fatigue on error of elbow joint sense. Methods : A total 19 healthy student(men = 10, women = 9) who did't have any problem of musculoskeletal system in upper extremities participated this study. we divided two groups into young group(n = 10, $19.67{\pm}.5$) and old group(n = 9, $28.56{\pm}1.5$). In order to evoke muscle fatigue of elbow flexor, we used Biodex, and participations performed concentric contraction of elbow flexor 150 numbers as well as we measured error of joint sense using by Biodex. We collected data just after, 30min, 2hour, 24hour after evoked muscle fatigue, and we finanlly acquired average value of three times measured joint sense of elbow joint. And we calculated value of percentage of error of joint sense. We analyzed collected data by repeated ANOVA, ANOVA using by SPSS ver.12.0 program. Result : This study showed that there was no significantly effects between groups and within groups, we could see that there was significantly difference among duration by each group of age, and sex(p<.05). Conclusion : The error of joint position sense presented highest value just period after evoked muscle fatigue compared after 30 min, 2 hours, 24 hours, and we can't find out interaction between duration and age and sex.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.13 no.2
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• pp.31-44
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• 2007

The purposes of this study were to examine the normal lumbar proprioception and identify the effect of vision and proprioception on lumbar movement accuracy through measuring a reposition error in visual and non-visual conditions and to provide the basic data for use of vision when rehabilitation program is applied. The subjects of this study were 39 healthy university students who have average physical activity level. They were measured the ability to reproduce the target position(50% of maximal range of motion) of flexion, extension, dominant and non-dominant side flexion in visual and non-visual conditions. Movement accuracy was assessed by reposition error(differences between intended and actual positions) that is calculated by the average of absolute value of 3 repeated measures at each directions. The data were analysed by paired samples t-test, independent samples t-test, and repeated measures ANOVA. The results were as follows : 1. Movement accuracy of flexion, extension, dominant side flexion, and non-dominant side flexion was increased in visual condition. 2. There were no differences in the lumbar movement accuracy between sexes in visual and non-visual conditions. 3. In non-visual condition, the movement in coronal plane(dominant and non dominant side flexion) is more accurate than that in sagittal plane(flexion and extension). 4. In non-visual condition, there were no differences in the lumbar movement accuracy between dominant and non-dominant side flexion. In conclusion, this study demonstrates that the movement is more accurate when the visual information input is available than proprioception is only available. When proprioception is decreased by injury or disease, it disturbs the control of posture and movement. In this case, human controls the posture and movement by using visual compensation. However it is impossible to prevent an injury or trauma because most of injuries occur in an unexpected situation. For this reason, it is important to improve the proprioception. Therefore, proprioceptive training or exercise which improve the ability to control of posture and movement is performed an appropriate control of permission or interception of the visual information input to prevent an excessive visual compensation.

• Physical Therapy Korea
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• v.12 no.3
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• pp.67-73
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• 2005

Prospective memory (PM) is related to remember to carry out a previously intented behaviour. The purpose of this study was to develop a paradigm for measuring PM function to diagnosis in mild cognitive impairment 1 or brain injury in patients 2. among brain injured patients Thirty-eight normal healthy subjects participated in current study. The paradigm was composed of four conditions: a baseline and three intention conditions (expectation, execution 1 and 2). In the expectation condition, subjects were asked to make a new response to intented stimuli during ongoing task, but the intented stimuli never occurred. In the execution 1 (one type of expected stimulus) and 2 (two types of expected stimuli), the intended stimuli did occur in 20% of trials. The reaction time and error rate were calculated in each condition. Repeated measures using ANOVA of subject's mean reaction times (RTs) and mean error rates (ERs) showed main effects of conditions during ongoing task. The comparison of PM tasks in executive condition 1 and 2 also showed significance in RTs and ERs. This paradigm reflects sufficiently the performance of prospective memory function during ongoing task in normal individuals. Thus, we suggest that the paradigm will be helpful to study neural network of PM function using brain imaging techniques and diagnosis of PM dysfunction.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.8
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• pp.1000-1007
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• 2011

For enlarging the applications of microstereolithography, the use of diverse materials is required. In this study, the material switching system (MSS) for projection microstereolithography apparatus is proposed. The MSS consists of three part; resin level control, resin dispensing control, and vat level control. Curing characteristic of materials used in fabrication has been identified. Through repeated fabrication of test models, the critical fabrication error is investigated and a possible solution to this error is suggested. The developed system can be applied to improve the strength of microstructure and extended to fabricate an array of microstructures with multiple materials.

• Radiation Oncology Journal
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• v.7 no.2
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• pp.299-303
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• 1989

Authors have developed highly reproducible calibration method for the Micro-Selectron HDR Ir-192 system (Nucletron, Motherland). The new jig has a 10cm radius circular hole in the $30cm{\times}30cm{\times}0.2cm$ acrylic plate, and 5F flexible bronchial tubes are attached around the hole. The source moves along the circle in the tubes and the ionization chamber is placed verticaly at the center of the circular hole (center of the jig). Dose distribution near the center was derived theoretically, and measured with the film dosimetry system. Theoretical calculation and measurement show the error margin below $0.1\%$ for 1mm or 2mm position deviation. We have measured at 12 and 24 points of circle with 1, 6, 11 and 21 second dwell time of source in order to calculate the activity of the source. Measurements have been repeated daily for 50 days. The accuracy and the reproducibility are below $1\%$ error margin. The half life of the source from our measurement is estimated $73.4\pm0.4$ days.