• Journal of the Korean Society for Precision Engineering
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• v.31 no.5
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• pp.381-387
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• 2014

This paper introduces a system to machine micro-sized patterns effectively on surface based on micro-milling process using tools with simultaneous rotation and oscillation, oscillation micro milling. To review the effectiveness of proposed concept, we integrated a micro-spindle supported by active magnetic bearings with a precision 3-axis air bearing stage using double-wedge mechanism, and tested this oscillation milling. Two types of oscillation milling were tested, which are linear oscillation milling with a flat end mill and elliptical oscillation milling with a ball end mill with 0.3 mm of diameter. The spindle was rotating 110 krpm and workpiece was moving constant speed of 2~8 mm/sec during the oscillation milling. As the results, multiple oval shape dimples were generated in regular spacing, and the variation of elliptical motion made different shapes of patterns. The results showed that proposed oscillation milling can be successfully used for machining repeated micro-patterns.

• Journal of the Korean Society of Safety
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• v.20 no.4 s.72
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• pp.148-153
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• 2005

Computer dominated jobs and industrial automation have rapidly created work-related musculoskeletal disorders(WMSDs) and WMSDS are expanding to employee of other general industry. Specific risk factors associated with WMSDs include repetitive motion, heavy lifting, forceful exertion, contact stress, vibration awkward posture and rapid hand and wrist movement. The purpose of this paper is to analyze the effects of the neck muscle workload according to posture(joint angle) and load weight. Seven male students participated in this study. To analyze neck muscle workload was studied on electromyographic(EMG) activity for sternocleidomastoid and trapezius, was subjectively rated using a Borg's CR-10 scale. ANOVA showed that the CR-10 ratings and most EMG root-mean-square (RMS) value were statistically significant improvement according to posture(joint angle) and load weight. The results of this study indicate the joint angle and weight of neck muscle workload to provide safe working conditions. To reduce the large number and severity of WMSDs employees have been experiencing, we need to redesign the job in workplace to identify and control hazards that are reasonably likely to be causing or contributing to the WMSDs.

• Journal of Sensor Science and Technology
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• v.31 no.6
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• pp.376-382
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• 2022

A triboelectric nanogenerator (TENG) can obtain electrical output due to the reciprocal motion between two objects (i.e., rubbing), in which repetitive contact is made. High reliability, stable output, and high reproducibility are important aspects of the electrical output obtained through a TENG as a sensor or generator, thus enabling its meaningful use. Therefore, many researchers fabricated TENGs into individual parts in the form of one module type to obtain high reproducibility and reliability. Since a TENG manufactured as a module type operates as a single device, it is possible to collect kinetic energy and convert it into electrical energy through the interaction between internally configured elements without the need for a separate structure. In addition, it is relatively easy to apply the size to the body, machine tools, and natural environment by simply adjusting the size suitable for use and surrounding environmental conditions. In this paper, the application cases of module-type TENGs are divided into four areas, and the research progress of module-type TENGs in each area is extensively reviewed.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.29 no.2
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• pp.39-48
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• 2023

Background: The position of pitcher requires a lot of repetitive motion, and because of this, it is known that not only professional baseball players, but also middle and high school players are frequently exposed to injuries in baseball. The purpose of this study is to examine the differences in upper extremity muscle activity during repeated pitching and the activity of each muscle during repeated pitching by analyzing middle and high school pitchers, divided into groups by age. Methods: Twenty participants (10 middle school male students and 10 high school male students) were recruited for this research. The outcome measures included neuromuscular motor control, including the upper trapezius (UT), triceps brachii (TB), deltoid (DT), latissimus dorsi (LD), biceps brachii (BB), pectoralis major(PM), extensor carpi radialis(ER), and flexor carpi radialis (FR). Results: The two-way analysis of varaince (ANOVA) was used to compare the muscle activity variables between the middle school and high school students. The one-way ANOVA was used to compare the muscle activity variables within time differences each groups. Conclusion: Our results provided promising clinical evidence that guide for upper extremity muscles to increase pitching efficiency in middle and high school base ball players.

• International Journal of Internet, Broadcasting and Communication
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• v.16 no.3
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• pp.121-138
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• 2024

Artificial intelligence is crucial to manufacturing productivity. Understanding the difficulties in producing disruptions, especially in linear feed robot systems, is essential for efficient operations. These mechanical tools, essential for linear movements within systems, are prone to damage and degradation, especially in the LM guide, due to repetitive motions. We examine how explainable artificial intelligence (XAI) may diagnose wafer linear robot linear rail clearance and ball screw clearance anomalies. XAI helps diagnose problems and explain anomalies, enriching management and operational strategies. By interpreting the reasons for anomaly detection through visualizations such as Class Activation Maps (CAMs) using technologies like Grad-CAM, FG-CAM, and FFT-CAM, and comparing 1D-CNN with 2D-CNN, we illustrates the potential of XAI in enhancing diagnostic accuracy. The use of datasets from accelerometer and torque sensors in our experiments validates the high accuracy of the proposed method in binary and ternary classifications. This study exemplifies how XAI can elucidate deep learning models trained on industrial signals, offering a practical approach to understanding and applying AI in maintaining the integrity of critical components such as LM guides in linear feed robots.

• Journal of the Ergonomics Society of Korea
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• v.34 no.4
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• pp.313-326
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• 2015

Objective: The objective of this research is to quantitatively analyze muscle activities of arm and shoulder, according to direction in various types of one-handed manual material handling, based on surface electromyography. Background: Workers in industrial sites frequently carry out one-handed manual material handling using arm and shoulder muscles. Therefore, chronic load and accumulated fatigue occur to arm and shoulder muscles, which becomes a main cause of upper arm and shoulder musculoskeletal disorders. The shoulder muscles have widely range of motion, and complex interactions take place among various muscles including rotator cuff muscles. In this regard, research on interactions among should muscles, according to such various dynamic motions, is required. Method: Ten male subjects in their 20s participated in this research. This research considered upward, downward, leftward, rightward, forward and backward directions and fourteen muscles around arm and shoulder (biceps brachii and trapezius, etc.) as independent variables. The mean muscle activity was set as the dependent variable. This research extracted $4^{th}{\sim}7^{th}$ repetition signals according to ten times of repetitive muscle contraction, and analyzed the muscle activity concerned using the envelope detection technique. Results: The mean muscle activity of upward direction was analyzed highly statistically significant. The reason is that the effect of gravity works to arm and shoulder muscles. Also, it is conjectured that deformation of coracoacromial ligament was caused, and its contact pressure increased, due mainly to the shoulder flexion, and therefore load was analyzed high. Muscle activity was analyzed significantly low, according to concentric ballistic motion used in the concentric contraction phase by storing elastic energy in the eccentric contraction phase with a motion to bring the weight to the front of subject's body as to downward, leftward and backward directions. Because, elbow joint's flexion-extension motions mainly occurred, biceps brachii was analyzed high muscle activity as the prime mover. Conclusion: The information on the quantitative load of muscles can be applied to ergonomic work design for one-handed manual material handling to minimize muscle load. Application: This research has effectively identified muscle activity according to dynamic contraction by applying an envelope detection technique. The results can be used for ergonomic work design to minimize muscle load during the one-handed manual material handling, according to each direction. The research results are expected to be used for musculoskeletal disorder prevention and physiotherapy in the rehabilitation medical field, based on the muscle load of arm and shoulder in various directions.

• Journal of the Ergonomics Society of Korea
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• v.27 no.4
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• pp.27-35
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• 2008

Recently, many studies have reported the fact that an excessively accumulated psychological and physical burden induced from physical labor conducted routinely in home and industry can be one of main reasons of musculoskeletal disorders in the working population. This fact makes increase interests in studies to reduce a risk of musculoskeletal disorders through grafting ergonomic considerations on working environment. However, there are currently limited methodologies in quantitative evaluations of new ergonomic suggestions to reduce a risk of musculoskeletal disorders. The current study is therefore performed to evaluate quantitatively effects of a design of washing machine as a new ergonomic suggestion onto prevention of musculoskeletal disorders, through application of a biomechanical evaluation methodology. For this, three-dimensional motion analysis by using musculoskeletal models with Rapid Entire Body Assessment (REBA), which has been generally used for a simple evaluation of a degree of harmfulness of the human body at specific working postures to be considered, was performed. The results of REBA did not give us enough information and their results were somewhat simple and inaccurate, but the results of the three-dimensional motion analysis give us enough information such as alteration of main muscle forces and joint moments required during washing work. All results showed that the main muscle strengths and joint moments were decreased effectively for reduction of a risk of musculoskeletal disorders during the washing work with newly designed washing machine evaluated in the current study, compared with those generated during the washing work with general washing machine. From these results, it can be concluded that a risk of the musculoskeletal disorders, which may be induced by a repetitive washing work, may be reduced through using the washing machine designed ergonomically and newly. Also, it is thought that if our ergonomic design can be applied for improvement of working environment in lifting and laying works conducted repeatedly for a treatment work of goods, which have a strong resemblance to the behaviors generated frequently during the washing work, a possibility of occurrence of the musculoskeletal disorders by the lifting and laying works may be reduced highly.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3046-3051
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• 2011

The third-rail system is an important device supplying power directly to the Maglev train through physical contact with the collecting shoe. It is directly related to safety and reliability for the running of Maglev. However, most the third-rail system used in Korea depend on foreign product or technologies, Korea Urban Maglev in the development of appropriate power feeding is urgent. In particular, the turnout section is the weakness point in the system because bending force by turnout section movement and fatigue caused by repetitive motion as well as the expansion by temperature, the forces by Maglev collecting shoe is added th the third-rail. Therefore, this paper proposes the third-rail system appropriate for Korean Urban Maglev of turnout section. To verify the structural stability of POSCO ICT third-rail system, the finite element analysis and physical testing was performed. The third-rail is fixed on each side of the turn-out section steel structure by epoxy insulation supporter and the integral behaviors are occurred. Therefore, the maximum horizontal displacements of each support are investigated and then, it is applied to finite element model of the third-rail to investigate the moments and stress. Also, the bending test about one million times and Expansion Joint for the third-rail was performed. The third-rail system safety and reliability was identified by test line on Korea Institute of Machinery & Materials in Deajeon for under the actual usage environment such as the Maglev and turn-out operation.

• Korean Journal of Optics and Photonics
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• v.23 no.6
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• pp.241-245
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• 2012

Measurements of the optical activity become very important issues in fields related to polymers, optical communications, astronomy, physics and many more. Hence it need to introduce this subject in our regular curriculum. In this experiment, an inexpensive, reliable, motorized polarimeter system which is suitable for undergraduate courses is constructed with PASCO's well-known Science Workshop 750 and a rotational motion sensor and light sensor, and the system is presented along with its experimental formulas. After responsivity of this system was checked by a half wave plate, and some repetitive experiments with 30% sucrose solution at 543.8 nm were performed. Comparing the experimental result with two calculated values from CRC data[1] showed that the specific rotation of the sucrose sample could be strongly suggested to be around +76 deg.cc/g.dm and it was an amply acceptable result for most undergraduate level courses.

• Journal of The Korean Association of Information Education
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• v.9 no.3
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• pp.397-406
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• 2005

The goal of this research is to prove the efficiency of direct instruction by developing and applying an ICT teaching and learning course for physical education based on a direct instruction model. The curriculum for physical education requires the instructors example and feedback, and sometimes classes may be difficult to conduct due to reasons such as weather conditions. Also, in actual learning, the application of a learning model is inadequate. In these cases, using an ICT teaching and learning course, experts can show examples instead. The learners are provided with individual and suitable feedback and can make it practical for them by slowing down motions, sectional motion learning, and repetitive learning. It can also enhance the sharing of the instructors teaching and learning methods. Therefore, this research recomposed the commonly used direct teaching and learning methods in physical education in order to make it suitable for ICT utilized lessons. It was recomposed in a procedural model and each level was explicated, and in order to materialize this, an ICT teaching and learning course was developed. This was then applied to a Fifth grade class, and its learning effects were analyzed.