With rapid growth of the global electric vehicle market, interest in the development of secondary batteries such as lithium batteries is also increasing. Core functional parts of secondary batteries are known to determine the performance of these batteries. Micro cracks, scratches, and markings that may occur during the manufacturing process must be checked in advance. As part of developing an automated inspection system based on machine vision, this study optimized the design of a linear feeder exposed to an environment with a specific operating frequency continuously to transfer parts at a constant supply speed. Resonance can occur when the natural frequency and the operating frequency of the linear feeder are within a similar range. It can negatively affect stable supply and the process of finding good or defective products during subsequent vision tests. In this study, vibration characteristics of the linear feeder were analyzed using mode analysis, frequency response analysis, and finite element analysis. An optimal design plan was derived based on this. After evaluating effects on vibration characteristics for structures in which vibrations or periodic loads such as mass and rails were continuously applied, the shape of the optimal linear feeder was presented using RSM.
Tire-related crashes account for a large proportion of all types of car accidents. The causes of tire-related accidents are inappropriate tire temperature, pressure, and wear. Although temperature and pressure can be monitored easily with TPMS, there exists no system to monitor tire wear regularly. This paper proposes a system that can estimate tire wear using a 3-axis accelerometer attached to the tread inside the tire. This system utilizes axial acceleration, extracts feature from data acquired with the accelerometer and estimates tire wear by feature classification using machine learning. In particular, the proposed tire wear estimation method is designed to estimate tread depth in four types (7, 5.6, 4.2, and 1.4 mm) at speeds of 40, 50, and 60 kmph. Based on the data obtained during several runs on a test track, it has been found that this system can estimate the tread depth with reasonable accuracy.
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A Study on Wheel Member Condition Recognition Using 1D–CNN Jin-Han Lee, Jun-Hee Lee, Chang-Jae Lee, Seung-Lok Lee, Jin-Pyung Kim, Jae-Hoon Jeong Sensors.2023; 23(23): 9501. CrossRef
The gear has a wide range of transmitted force as various gear ratios are possible using a combination of teeth. It can transmit power reliably and cause relatively little vibration and noise. For this reason, the application of reducers of electric vehicles is being expanded. Vibration noise generated from gears is propagated into the quiet interior of a vehicle, causing various claims. In most gear studies, transmission error has been pointed out as the main cause of vibration noise of gears. Transmission errors have various causes, including design factors, manufacturing factors, and assembly factors. In general, when predicting transmission error through finite element analysis, design factors play an important role without considering manufacturing factors or assembly factors. In this study, relationships among important design variables (gear module, compensation rate, load torque, and transmission error) in gear design were investigated using analytical and experimental methods. In addition, a method of predicting gear meshing stiffness through the predicted gear transmission error was proposed to obtain variation of meshing stiffness due to changes of gear design parameters.
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Development of a Prediction Model for the Gear Whine Noise of Transmission Using Machine Learning Sun-Hyoung Lee, Kwang-Phil Park International Journal of Precision Engineering and Manufacturing.2023; 24(10): 1793. CrossRef
This paper introduces PongBot, a quadruped robot developed for preparation in the Dronebot Challenge held in Jangseonggun, Jeollanam-Do, South Korea in November 2020. The Dronebot Challenge, hosted by the Army Headquarters, is a competition to demonstrate that drones and robots can be useful for military purposes. In 2020, this competition consisted of a total of 8 events and we participated in the ‘Traveling on rough terrain’ event, which consisted of various terrains, such as, slopes, unpaved roads, and streams. PongBot is a quadruped robot that uses an electric motor and can walk for more than an hour on various terrains. Also, according to the rules of the competition, the robot had a system which could be remotely controlled from a ground control station. In addition, by applying the SLAM algorithm, the robot operator received information about its surrounding environment, thereby deriving records to facilitate the operation. The performance of this robot system and SLAM algorithm was verified through this competition.
In this study, experiments were performed to determine if the pattern fabricated by the UV nano imprint process could be modified using additional processes such as surface treatment. We wanted to confirm the fabrication possibility of a special pattern such as the reverse trapezoidal shape difficult to produce because of the releasing problem. The UV ozone treatment (Hydrophilic Treatment) and OTS coating (Water Repellent Treatment) were used and shape modification occurred under controlled treatment time. As a result of performing the UV ozone treatment for 30 minutes or more on a micro pattern manufactured by UV curing resin of PUA series, the contraction phenomenon of the micro structure occurred and the shrinkage was dependent on treatment time. When the OTS treatment was performed, the surface of the microscale pattern could be roughened. When the nanoscale pattern was treated, the pattern change could be induced. It was possible to partially cure the resin by adjusting the UV absorption using dye material, and the deformation of the pattern was made by an additional pressing process. As a result of the experiment of the various methods causing the shape change of the cured pattern, the possibility of the methods was verified.
The goal of this research is to develop intelligence data analytics system for quality enhancement of die-casting process. Targeting a die-casting factory in Korea, we first constructed an edge device-based infrastructure with wireless communication environment for data collection and a processing infrastructure to support the intelligence data analytics system. Using the real quality regarding data of the target factory, we developed two data analytics models for defect prediction and defect cause diagnosis using AdaBoostC2 algorithm. Accuracy of the developed data analytics model for defect prediction was verified as 86%. To use the developed data analytics model efficiently and produce a sequential process of data analytics model generation, execution, and update were conducted automatically. The edge device and integrated server-based dualized analysis system was proposed. The developed intelligence data analytics system was applied to the target factory, and the effectiveness was demonstrated.
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Development of AI-based Bearing Machining Process Defect Monitoring System Dae-Youn Kim, Dongwoo Go, Seunghoon Lee Journal of Society of Korea Industrial and Systems Engineering.2025; 48(3): 112. CrossRef
Development of a Quality Prediction Algorithm for an Injection Molding Process Considering Cavity Sensor and Vibration Data Jun Kim, Ju Yeon Lee International Journal of Precision Engineering and Manufacturing.2023; 24(6): 901. CrossRef
Data-analytics-based factory operation strategies for die-casting quality enhancement Jun Kim, Ju Yeon Lee The International Journal of Advanced Manufacturing Technology.2022; 119(5-6): 3865. CrossRef
Development of a cost analysis-based defect-prediction system with a type error-weighted deep neural network algorithm Jun Kim, Ju Yeon Lee Journal of Computational Design and Engineering.2022; 9(2): 380. CrossRef
Development of Prognostics and Health Management System for Rotating Machine and Application to Rotary Table Mingyu Kang, Chibum Lee Journal of the Korean Society for Precision Engineering.2022; 39(5): 337. CrossRef
Server-Edge dualized closed-loop data analytics system for cyber-physical system application Jun Kim, Ju Yeon Lee Robotics and Computer-Integrated Manufacturing.2021; 67: 102040. CrossRef
Die-Casting Defect Prediction and Diagnosis System using Process Condition Data Ji Soo Kim, Jun Kim, Ju Yeon Lee Procedia Manufacturing.2020; 51: 359. CrossRef
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A spectral-domain interferometer with dual reference paths and orthogonal polarization states to avoid measurement errors when interference signals overlap is proposed and realized. In our previous study, by using dual reference mirrors, two inherent problems of the spectral-domain interferometer, the non-measurable range and the directional ambiguity problem, were successfully solved. However, because of the overlap of interference signals, the absolute distance values were distorted. In this study, the polarization states of beams from two reference paths were made orthogonal to eliminate the interference signal between them, so that the overlap can be essentially avoided. First, we performed a numerical simulation on the measurement error with respect to the degree of superposition of the interference signals. Simulation results show that with the previous method the measurement error can be up to approximately 1 μm within the overlap region, but the proposed method drastically reduced this error to below 100 nm. Then, the proposed method was experimentally realized and verified. In conclusion, the proposed method can measure the absolute distances without the inherent problems as well as the measure errors caused by the overlap of the interference signals.
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Sub-100-nm precision distance measurement by means of all-fiber photonic microwave mixing Yoon-Soo Jang, Jungjae Park, Jonghan Jin Optics Express.2021; 29(8): 12229. CrossRef
Rolled and extruded aluminum (Al) products have been widely used in heat exchanging systems using the boiling heat transfer (BHT) mechanism. The BHT coefficient can be increased on a rough surface due to the activation of the nucleation sites. In this study, the BHT characteristic of an Al plate with directional surface roughness (bare Al plate), which was generated in rolling or extrusion process, was measured and compared with the polished Al plates with non-directional surface roughness. The BHT coefficient of polished Al plate was increased with increasing surface roughness, saturated at ~300 nm (Sa). Although the surface roughness of the bare Al plate was 380-430 nm (Sa), the BHT coefficient of bare Al plates were lower than the polished Al plates with similar surface roughness. To examine the lower BHT coefficient of bare Al plate, the directional surface roughness was characterized by vertical and horizontal surface roughness values to the production direction, and we experimentally concluded the lower surface roughness value (horizontal surface roughness) was the dominant factor for the BHT characteristic of a rolled or extruded Al plate with directional surface roughness.
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Three-dimensional fin-tube expansion process to achieve high heat transfer efficiency in heat exchangers Seong-Yeop Kang, Sae-Rom So, Yong Son, Seonghun Park, Man-Yeong Ha, Sang-Hu Park Journal of Mechanical Science and Technology.2019; 33(9): 4401. CrossRef
Basic Experimental Study on Fin-Tube Expansion Process Using an Additive Manufactured Spiral-Grooved-Expanding Ball Seong Yeop Kang, Changwan Han, Yong Son, Seong Hun Park, Sang Hu Park Journal of the Korean Society for Precision Engineering.2019; 36(7): 667. CrossRef
Basic Experimental Study on Fin-Tube Expansion Process Using an Additive Manufactured Spiral-Grooved-Expanding Ball Seong Yeop Kang, Changwan Han, Yong Son, Seong Hun Park, Sang Hu Park Journal of the Korean Society for Precision Engineering.2019; 36(7): 667. CrossRef
An air cooling system using an axial flow fan is generally applied in an electronic cabinet on shipboard. However, cases that apply a water cooling system or a mixture of water cooling and an air cooling system are gradually increased by applying the high-performance SBC (Single Board Computer) or DSP (Digital Signal Process), which has a high heating value. In this study, a structure borne noise reduction design for an electronic cabinet that applied a mixture of air and water cooling system was performed. First, the cooling system design was performed using a numerical analysis to secure a thermal stability, and then an electronic cabinet was produced. Next, considering the cooling performance, the reduction design for structure borne noise that causes an underwater radiated noise was performed using the experimental approach. The electronic cabinet, which has a thermal stability and meets the structure borne noise specifications, was finally developed.
Recently, with the development of the IT industry, technology for satellite communication network systems using multichannel, high-capacity data is getting increasingly popular. Especially in the field of defense, experts emphasize the necessity for research and development (R&D) to improve communication quality in order to facilitate Network-Centric Warfare (NCW) and increase mission efficiency through the use of satellite communication network systems. High power is required for the implementation of this technology, and its quality is greatly affected by Passive InterModulation Distortion (PIMD). In order to improve PIMD levels, the leakage characteristics of the system were analyzed with knowledge of the strong influence of the state of the flange joint that has been confirmed by years of experience and previous studies. In this paper, we analyzed various problems from the mechanical point of view in order to improve the radio frequency (RF) performance by minimizing PIMD in the X band, which is used for the satellite communication. Based on our findings, we propose the flange shape to achieve the test result of -150 dBm, which is an improvement from the existing PIM performance and reference level.
Inverter-Type refrigerators are known to consume less energy by varying the inverter frequency according to indoor temperatures and refrigerant pressure through indoor-outdoor communication. However, many commercial operators cannot afford to replace indoor units with ones capable of communication. In a non-communication configuration, indoor units are connected with an inverter-type outdoor unit without intercommunication abilities. The research goal is finding appropriate operating parameters to achieve energy efficiency. Thus, an operation algorithm with two modes is proposed, i.e., one to search the best operating parameters and one for normal operation with the best parameters. The experimental evaluation showed 11.27% reduction in energy consumption, indicating a good applicability of the algorithm.
This paper presents the development of a magneto-optical encoder for higher precision and smaller size. In general, optical encoders can have very high precision based on the position information of the slate, while their sizes tend to be larger due to the presence of complex and large components, such as an optical module. In contrast, magnetic encoders have exactly the opposite characteristics, i.e., small size and low precision. In order to achieve encoder features encompassing the advantages of both optical and magnetic encoders, i.e., high precision and small size, we designed a magneto-optical encoder and developed a method to detect absolute position, by compensating for the error of the hall sensor using the linear table compensation method. The performance of the magneto-optical encoder was evaluated through an experimental testbed.
Weight bearing is effective during rehabilitation of gait, in the elderly and disabled people. Various training devices using weight bearing function were developed along with treadmill walking; however, no device has been developed in conjunction to walking on the ground. Here, we designed a rail type frame of a gait rehabilitation system for body-weight support (BWS) function, and analyzed its mechanical safety in the static weight bearing condition of a vertical axis. Computational simulations were performed to analyze structure of the driving parts, which are connected with a rail and driving rollers and the lower plate of the BWS. Structural analyses showed the drivers and BWS were safe, when simulated at 135kg weight under static conditions. Thus, this rail type rehabilitation system can be used for gait training of the elderly and disabled.
This paper reports on the development of a roller-cam clutch mechanism. This mechanism can transfer bidirectional torque with high backdrivability, as well as increase actuation energy efficiency, in electrical exoskeleton robots. The developed mechanism was installed at the robot knee joint and unclutched during the swing phase which uses less metabolic energy, thereby functioning as a passive joint. The roller-cam clutch aimed to increase actuation energy efficiency while also producing high backdrivability by generating zero impedance for users during the swing phase. To develop the mechanism, mathematical modeling of the roller-cam clutch was conducted, with the design having more than three safety factors following optimization. Titanium (Ti-6AL-4V) material was used. Finally, modeling verification was done using ANSYS software.
Energy harvesting is a clean technology to obtain energy from the surrounding environment such as wind, sun, vibration and so on. In particular, the current TPMS (Tire Pressure Monitoring Device) is very small and attached to the outside of a vehicle and power supply of the TPMS is limited. Therefore, energy harvesting using vibration energy of piezoelectric materials is important to the TPMS. In this paper, we analyzed several models using ANSYS which is one of the FEA (Finite Element Analysis) package and compared corresponding strain frequency response functions of the TPMS. In addition, we confirmed that dynamic characteristics variations according to geometry changes have effects on the performance of the TPMS.
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