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JKSPE : Journal of the Korean Society for Precision Engineering

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"Dong Ju Lee"

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"Dong Ju Lee"

Articles
Optimal Design of 50 ton Hydraulic Breaker Housing
Jai Hak Lee, Dong Ju Lee, Jun Young Choi
J. Korean Soc. Precis. Eng. 2022;39(4):269-275.
Published online April 1, 2022
DOI: https://doi.org/10.7736/JKSPE.021.105
An optimal design was developed for housing of a 50-ton hydraulic breaker. A four-factor, two-level design was created using the full factorial design, and it was confirmed that the safety factor, the response value, exhibited a curvature. As the curvature was confirmed, a higher-order experiment, a response surface analysis was performed. Based on the Minitab"s optimized prediction of the safety factor and weight, the actual analysis was performed using ANSYS Workbench, the finite element analysis program. As a result, the safety factor was 2.03 and the weight was 3222.2 kg, which was almost consistent with the Minitab’s prediction. The safety factor decreased from 2.33 to 2.03 compared to that in the initial model, but the optimization model can also be judged as being safe because the safety factor was set to 2.00. The weight was reduced by 119.1 kg, from 3341.3 to 3222.2 kg.
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A Study for Measuring Assembly Misalignment of High Maneuver Precision Guidance Missile
Seung Hyuk Choi, Kwang Won Lee, Moo Yong Ryu, Sung Yong An, Dong Ju Lee
J. Korean Soc. Precis. Eng. 2019;36(10):921-928.
Published online October 1, 2019
DOI: https://doi.org/10.7736/KSPE.2019.36.10.921
The assembly misalignment of a high maneuver precision guidance missile such as anti-air interceptor could have poor influence on the performance of the system and lead to fatal mission failure. Thus, several methods to minimize the assembly misalignment of missiles have been suggested, including assembly guiding tools and measuring devices. However, previously suggested solutions have disadvantages in versatility and cost. In this study, the low cost and universally applicable solution based on inclinometers for measuring assembly misalignment of a missile is introduced. The comparison between measurement data of the suggested system and a three-dimensional laser tracker for a missile assembly misalignment was conducted. The results show the suggested system can quantify a missile assembly misalignment with comparable precision and accuracy.
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A Study on the Friction of Tire Tread Rubber using High-Speed Friction Test Machine
Jin Koo Lee, Dong Ju Lee
J. Korean Soc. Precis. Eng. 2013;30(6):622-628.
Published online June 1, 2013
Due to the development of compounding technology, there is a considerable increase in the number of high performance rubbers in the world. Accordingly, there are rapid growing requests about high performance tires such as UHP tire and Run-flat tire. However, it is extremely difficult to investigate the friction coefficient of tire tread rubbers. An alternative solution must be developed with the reliability of high-speed linear friction test machines. The use of friction test machines can be expected to improve rubber friction researches. In this paper, we propose a new kind of high-speed linear friction test machine. We have designed and manufactured various mechanisms for friction tests. The final goals are to design and manufacture friction test machines that can investigate friction coefficients efficiently and rapidly. The performance of the proposed high-speed linear friction test machine is evaluated experimentally; however additional study should be necessary for safer and more reliable experimentation.
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A Study on the Performance of Window Cleaning Robots in High-Rise Building
Jin Koo Lee, Dae Myoung Kim, Dong Ju Lee
J. Korean Soc. Precis. Eng. 2013;30(4):390-396.
Published online April 1, 2013
Due to the development of technology, there is a considerable increase in the number of skyscrapers in the world. Accordingly, there are rapid growing requests about maintenances such as cleaning, painting, and inspection. However, it is extremely dangerous working the walls of buildings, and crashes from buildings have accounted for large proportion of constructional accidents. Especially, as the number of buildings with irregular shapes increases, the accident rate during the maintenance work increases each year, and most of the accidents lead to death. An alternative solution must be developed with the commercialization of automatic systems. In this research, a fundamental research has been conducted for drafting and commercializing an automation tool that is carried in the built-in guide system, which can perform cleaning.
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A Study of Automatic Cleaning Tool Design for Façade in High-rise Buildings
Jin Koo Lee, Dong Ju Lee
J. Korean Soc. Precis. Eng. 2012;29(1):56-63.
Published online January 1, 2012
Due to the development of construction technology, there is a considerable increase in the number of skyscrapers in the world. Accordingly, there are rapid growing requests about maintenance systems such as cleaning, painting, and monitoring the processes of facade in highrise buildings. However, it is extremely dangerous working the walls of high-rise buildings, and crashes from buildings have accounted for large proportion of constructional accidents. An alternative solution must be developed with the commercialization of automatic robot systems. For the last decade, interest in developing robots for cleaning and maintenance in facade of highrise buildings has continuously increased. The use of automatic robot systems can be expected to reduce accidents and decrease labor costs. In this paper, we propose a new kind of cleaning mechanism. We have designed and manufactured various cleaning tools for different types of facades with economic commercialization. The cleaning cycle, size, and intensity will be determined by economic constraints as well. The final goals are to design and manufacture tools and robots that can clean facades efficiently and rapidly even in dangerous places. The cleaning tool systems consist of nozzles, brush rollers, and squeezing devices. Furthermore, these tools and robots perform each process utilizing the systems of built-in guide types and gondola types for building maintenance. The performance of the proposed cleaning tools is evaluated experimentally; however additional study should be necessary for safer and more stable commercialization.
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Estimation of Shoulder Flexion Torque and Angle from Surface Electromyography for Physical Human-Machine Interaction
Kihan Park, Dong Ju Lee, Jung Kim
J. Korean Soc. Precis. Eng. 2011;28(6):663-669.
Published online June 1, 2011
This paper examines methods to estimate torque and angle in shoulder flexion from surface electromyography(sEMG) signals for intuitive and delicate control of robotic assistance device. Five muscles on the upper arm, three for shoulder flexion and two for shoulder extension, were used to offer favorable sEMG recording conditions in the estimation. The methods tested were the mean absolute value (MAV) with linear regression and the artificial neural network (ANN) method. An optimal condition was sought by varying combination of muscles used and the parameters in each method. The estimation performance was evaluated using the correlation values and normalized root mean square error values. In addition, we discussed their possible use as an estimation of motion intent of a user or as a command input in a physical humanmachine interaction system.
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The Supplement of Sn/Cu, Plating Solution Affects in Plating Skim Quality of the Plating Product
Taeg Jong Jeon, Jun Bin Ko, Dong Ju Lee
J. Korean Soc. Precis. Eng. 2009;26(7):112-119.
Published online July 1, 2009
The purpose of this study is to evaluate the evaluation of process yield performed by using Sn & Cu treatment on the surface to optimize process condition for Lead-free solder application. The materials which are used for the New Surface Treatment study are Semi-Dulling plating for high speed Sn/Cu alloy of Soft Alloy GTC-33 Pb free known as “UEMURA Method” and plating substrate is alloy 42.Especially in lead-free plating process, it is important to control plating thickness and Copper composition than Sn/Pb plating. Evaluated and controlled plating thickness 12±3㎛, Copper composition 2±1%, plating particle and visual inspection. The optimization of these parameters and condition makes it makes possible to apply Sn/Cu Lead-free solder from Sn/Pb alloy.
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A Study on the Machining Characteristics of Ti-6Al-4V Alloy
Nam Yong Kim, Jun Bin Ko, Dong Ju Lee
J. Korean Soc. Precis. Eng. 2003;20(4):20-28.
Published online April 1, 2003
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Process Design of the Hot Pipe Bending Process Using High Frequency Induction Heating
Keong Rye Ryu, Dong Ju Lee, Dong Jin Kim, Byung Min Kim, Kwang Ho Kim
J. Korean Soc. Precis. Eng. 2001;18(9):110-121.
Published online September 1, 2001
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