To maintain communication quality of a mobile satellite antenna system without disconnection, the satellite tracking technique is required. There are two major tracking methods called step tracking and monopulse tracking, which utilize satellite signals as a tracking feedback. The monopulse tracking method provides fast and accurate tracking performance, whereas it can be used only in limited small regions near the satellite’s direction. In the case of step tracking method, it can be applied in relatively large regions. However, this method also has a limitation, in that it cannot provide fast and accurate tracking performance near the satellite direction. In this paper, a hybrid tracking method composed of step tracking mode and monopulse tracking mode is proposed. The proposed tracking method can present accurate tracking performance near the satellite direction as well as be applied in relatively large regions.
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.
It is generally accepted that mechanical properties of sandwich composite are affected by curing pressure variation. For the present study, the effects of curing pressure variation on the compressive properties of balsa wood sandwich composite were investigated. For this purpose, a compressive test was conducted using balsa wood and honeycomb core sandwich composite, applying 40 psi and 60 psi curing pressure conditions. The results showed that compressive load of balsa wood sandwich composite applying 60 psi curing pressure condition is higher than applying a 40-psi curing condition. This phenomenon is due to an increase in the adhesive strength of the balsa wood sandwich composite as the curing pressure increases, thereby improving the compressive strength. Deboning and local buckling were observed on fracture surfaces of all balsa wood sandwich composite, but only global buckling was observed at honeycomb core sandwich composite.
This paper investigated the influence of the backlash ratio on frequency response characteristic in servo systems with twostage gear reducer, according to the change of magnitude of motor input voltage. The backlash ratio is defined as the ratio of the first gear stage backlash magnitude in relation to total backlash magnitude. This paper presents that the maximum anti-resonance and resonance frequency of the system can take place at the maximum backlash ratio if the motor input voltage of the system is large. On the other hand, if the motor input voltage is small, the maximum anti-resonance and resonance frequency of the system will occur at an arbitrary backlash ratio. In order to develop the geared servo system with fast response, it is effective to increase the maximum allowable motor input voltage and to reduce the magnitude of backlash on the second gear reduction stage.
Citations
Citations to this article as recorded by
Frequency Analysis of the Servo System with Three-Stage Reducer considering the Backlash Ratios and Motor Input Voltage Joo Hyun Baek, Tae Young Chun, Jong Geun Jeon, Young Hwan Jo Journal of the Korean Society for Precision Engineering.2021; 38(9): 691. CrossRef
Backlash Compensation for Accurate Control of Biopsy Needle Manipulators having Long Cable Transmission Gun Rae Cho, Seong-Tae Kim, Jung Kim International Journal of Precision Engineering and Manufacturing.2018; 19(5): 675. CrossRef
A Review of Recent Advances in Design Optimization of Gearbox Zhen Qin, Yu-Ting Wu, Sung-Ki Lyu International Journal of Precision Engineering and Manufacturing.2018; 19(11): 1753. CrossRef
Tactical devices and equipment are usually loaded on a trailer vehicle within a shelter system. When the vehicle is moving fast and passing other vehicles, side panels of the shelter are deformed and tilted by pressure waves. Also, the vehicle is subjected to the effects of wind load and centrifugal force with the pressure waves at severe conditions. In this study, a theoretical analysis of overturn calculated by CFD (Computational Fluid Dynamics) and experiments is applied to the vehicle. Deformations of the side panel are measured for experimental validation of the CFD model. As a result, the safety factor of the driving stability of the vehicle is derived by theoretical analysis in the severe situation predicted by the validated CFD model.
In this study, a numerical analysis for predicting the internal pressure of the flight vehicle system with relief valve and N2-injection type cooler was conducted to operate the system safely in an unsteady-state condition. By adopting an incompressible ideal gas equation to computational domain at each time step, internal pressure was calculated without iteration. To increase the accuracy of the numerical analysis results, numerical model was correlated by modifying the volume of the computational domain. To modify the volume of computational domain, internal pressure along time was compared with experimental results. It showed good agreement within system operating time. Air mass flow rate at the relief valve is calculated by interpolating the performance curve data. For accurate and rapid calculation of the internal pressure in an unsteady-state condition, time step size convergence study was conducted additionally. By using a correlated numerical model, Pcr of the relief valve is conducted to remain the flight vehicle system within an internal pressure range of 0.6-2.0 atm, in each flight profile. Finally, specific Pcr of relief valve was applied to the system and the experimental results showed that the internal pressure remained in a safe range.
An integrated simulation program for virtual laser ablation is developed to help understand and predict the effects of machining parameters on the final machined results. The main solver of the program is based on the model for polymer ablation with short-pulse Excimer lasers. The GUI of the program is built using Visual Fortran and OpenGL so that the user can work in a visual environment, such as Windows on a PC, where the important machining parameters can be input via a dialog box and the calculated results for the machined shape can be plotted by means of a 3D graphics window using OpenGL. The developed GUI can be implemented for use with most pre-developed FORTRAN solvers for Windows application, allowing the user to control the input parameters and to see the results in a 3D plot; hence most FORTRAN users could create their own visual programs on PC Windows systems similarly, widening the range of application of FORTRAN solvers.
In this investigation, a locking mechanism was proposed for electronic products that have battery covers. The exterior design of electronic products has been advanced with diversified materials including polymers and metals. Unlike polymers such as polycarbonate, metals are not easily deformed. Therefore, products with a metallic exterior have an added button to release the battery cover, which limits the quality of the exterior design. In this study, a new design without a release button that included a miniature solenoid inside the product was proposed. The Taguchi method was used to maximize the attraction force of the solenoid while, at the same time, minimizing its dimensions.
Citations
Citations to this article as recorded by
Design and optimization of a novel solenoid with high magnetic uniformity Xuehua Zhu, Meng Xing, Juntao Ye, Xinyu Liu, Ziruo Ren Scientific Reports.2024;[Epub] CrossRef
This paper presents an analysis of the stiffness and fatigue life of double-row angular contact ball bearings (D-ACBBs). To this end, a comprehensive quasi-static model was developed for D-ACBBs subjected to five degree-of-freedom (DOFs) loading and displacement. The model was verified by a commercial computational program. A rigorous numerical investigation was performed, based on the developed model regarding the effects of external load, rotational speed, axial clearance, bearing arrangement, and angular misalignment on the stiffness and fatigue life of the D-ACBB. The D-ACBB was subjected to negative axial clearance and yielded improved performance in terms of fatigue life and stiffness. The effect of angular misalignment on the bearing fatigue life was found to be significantly dependent on the amount of axial clearance. The moment stiffness of the D-ACBB in a back-to-back arrangement was higher than the face-to-face arrangement owing to the increased effective load center distance, whereas the radial stiffness and fatigue life were almost unchanged for back-to-back and face-to-face arrangements.
Citations
Citations to this article as recorded by
Analytical Prediction of Fatigue Life for Roller Bearings Considering Impact Loading Yuwei Liu, Haosen Gong, Yufei Li, Zehai Gao, Tong Zhao Processes.2025; 13(8): 2545. CrossRef
Machine Tool Research Trends in Korea Gyuho Kim, Seung-Kook Ro, Chun-Hong Park International Journal of Automation Technology.2025; 19(4): 363. CrossRef
Multi-objective optimization design of wheel hub bearings based on Kriging-NSGA-II Ming Qiu, Jiaming Zhang, Huijie Wang, Chuanmeng Yang, Yibo Tang, Peinan Zhang Journal of Mechanical Science and Technology.2024; 38(3): 1341. CrossRef
Enhanced Fatigue Life Estimation Formula for Angular Contact Ball Bearings Subjected to Combined Loading Jin Hyeok Sa, Gilbert Rivera, Chan-Sik Kang, Seong Wook Hong Journal of the Korean Society for Precision Engineering.2024; 41(3): 231. CrossRef
Combined analysis of stiffness and fatigue life of deep groove ball bearings under interference fits, preloads and tilting moments Yi Jiang, Tianyu Zhu, Song Deng Journal of Mechanical Science and Technology.2023; 37(2): 539. CrossRef
Stiffness Characteristics of Crossed Roller Bearings With Roller Roundness Deformation Van-Canh Tong, Seong-Wook Hong Journal of Tribology.2022;[Epub] CrossRef
The stiffness characteristics analysis of the duplex angular contact ball bearings based on a comprehensive multi-degree-of-freedom mathematical model Tengfei Xu, Lihua Yang, Wei Wu, Yaoyu Han, Endian Xu, Kai Wang Applied Mathematical Modelling.2022; 106: 601. CrossRef
Characteristics of Duplex Angular Contact Ball Bearing with Combined External Loads and Angular Misalignment Tengfei Xu, Lihua Yang, Kai Wang Applied Sciences.2020; 10(17): 5756. CrossRef
Modeling of Crossed Roller Bearings Considering Roller Roundness Deformation Van-Canh Tong, Eui-Wook Jung, Seong-Wook Hong Journal of Tribology.2020;[Epub] CrossRef
Modeling of Displacements in a Large-Size Rotary Table Subjected to Loads Hyeon-Il Oh, Van-Canh Tong, Woo-Sang Park, Seong-Wook Hong Journal of the Korean Society for Precision Engineering.2018; 35(4): 443. CrossRef
Study on the Dynamic Characteristics and Fatigue Life of a Spindle-Bearing System for Large Machine Tools Hyeon-Il Oh, Sun-Woong Kwon, Woo-Sang Park, Seong-Wook Hong Journal of the Korean Society of Manufacturing Technology Engineers.2018; 27(6): 591. CrossRef
Spinal stability is controlled by two interrelated systems: the spinal column including ligaments and the muscular control system. In addition to these systems, the thoracolumbar fascia (TLF) also interacts with the muscular system to maintain the stability of the spine. The effects of the tensioning of TLF on the spinal stability was investigated using computational analysis. The stability of the spine was analyzed with a three-dimensional finite element model of musculoskeletal system including TLF. The paraspinal muscle activities were calculated based on a hypothesis: the intervertebral disc was assumed to have a transducer function and the muscle is activated according to a sensor driven control mechanism to maintain stability of the lumbar spine. Muscle forces were calculated in examining 40o isometric forward flexed and erect standing postures. As a result, the fascial tension induced a decrease in superficial muscle activity while maintaining the spinal stability.
Citations
Citations to this article as recorded by
A Novel Wall Touch-Single Limb Stance Exercise for Dynamic Activation o f Gluteus Maximus - A Cross Sectional Study Babina Rani, Shivam Sharma, Prerana Berwal, Ritu Shree, Mandeep S. Dhillon Journal of Orthopaedics.2023; 41: 33. CrossRef
Analysis in the Change of Paraspinal Muscle Activities and Adjacent Disc Degeneration according to the Segmental Fusion Hae Won Choi, Young Eun Kim Journal of the Korean Society for Precision Engineering.2018; 35(7): 721. CrossRef
This study aimed to investigate the effects of static stretching of the calf muscle on ankle position sense and dynamic balance ability following microwave diathermy. Participants were 28 healthy young students in their 20 s, who were divided into a microwave diathermy stretching group (MSG) and a stretching group (SG). A microwave was emitted to the calf muscle area to participants in the MSG. Static stretching was performed by standing on a quadriceps board for 15 minutes. The angle of the wedge was set to a range of 15–25°, representing a level of pain and discomfort allowed by the subjects. Before and after intervention, ankle dorsi-plantar flexion joint position sense (JPS) and dynamic balance ability were measured. The group source affected JPS error of dorsi-plantar flexion (p < 0.05) and JPS error increased with the SG more than the MSG. There was an increase in the dynamic balance score in both groups after the intervention compared to before the intervention. Microwave therapy prior to stretching can preserve JPS and balance ability, thereby reducing the risk of injuries from activities after stretching.
Citations
Citations to this article as recorded by
The influence of acute static stretching on the ankle joint-position sense of soccer players: A randomized controlled crossover trial Joana Azevedo, António Moreira, Isabel Moreira-Silva, Ricardo Cardoso, Adérito Seixas Journal of Bodywork and Movement Therapies.2025; 42: 1011. CrossRef
Relationship between Hip Joint Position Sense and Balance Abilities Daehee Lee, Seulki Han Journal of the Korean Society for Precision Engineering.2018; 35(12): 1205. CrossRef
In this study, application study of the life cycle assessment (LCA) is conducted on a composite small craft for sustainable design and production according to ISO 14040-14044 series. Procedure of general LCA is reconstituted to apply to composite small craft, and life cycle inventory (LCI) analysis is conducted on principal structures of composite small craft by developing a process flow diagram for boat building. Also, this study leads LCA results of structures and materials into the environmental impact category such as carbon footprint, water eutrophication, air acidification, and energy consumption. Especially, LCA results about production methodologies that are hand lay-up and vacuum infusion of glass fiber reinforced plastic are quantitatively compared and analyzed.
Citations
Citations to this article as recorded by
Analysis of Life Cycle Assessment (LCA) for Sustainable Basic Design Alternatives for Medium-Sized LNG-DF Propulsion Ship Ki Seok Jung, Dong Kun Lee Journal of the Society of Naval Architects of Korea.2023; 60(5): 358. CrossRef
A case study for 3D scanning-based quantitative quality control during key stages of composite small craft production Dong-Kun Lee, Bon-Yeong Park International Journal of Naval Architecture and Ocean Engineering.2023; 15: 100534. CrossRef
A Case Study on the Sustainability for a Stanchion of Recreational Crafts based on the Design for Additive Manufacturing Using a FFF-type 3D Printer Dong-Kun Lee, Bon-Yeong Park Journal of the Society of Naval Architects of Korea.2021; 58(5): 294. CrossRef
First
Prev
