• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.9
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• pp.72-80
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• 2019

In this task, the tool dynamometer design and manufacture, and the Ansys S/W structural analysis program for tool attachment that satisfies the cutting force measurement requirements of the tool dynamometer system are used to determine the cutting force generated by metal cutting using 3-axis static structural analysis and the LabVIEW system. The cutting power in a cutting process using a milling tool for processing metals provides useful information for understanding the processing, optimization, tool status monitoring, and tool design. Thus, various methods of measuring cutting power have been proposed. The device consists of a strain-gauge-based sensor fitted to a new design force sensing element, which is then placed in a force reduction. The force-sensing element is designed as a symmetrical cross beam with four arms of a rectangular parallel line. Furthermore, data duplication is eliminated by the appropriate setting the strain gauge attachment position and the construction of a suitable Wheatstone full-bridge circuit. This device is intended for use with rotating spindles such as milling tools. Verification and machining tests were performed to determine the static and dynamic characteristics of the tool dynamometer. The verification tests were performed by analyzing the difference between strain data measured by weight and that derived by theoretical calculations. Processing test was performed by attaching a tool dynamometer to the MCT to analyze data generated by the measuring equipment during machining. To maintain high productivity and precision, the system monitors and suppresses process disturbances such as chatter vibration, imbalances, overload, collision, forced vibration due to tool failure, and excessive tool wear; additionally, a tool dynamometer with a high signal-to-noise ratio is provided.

• Journal of Aerospace System Engineering
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• v.14 no.3
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• pp.69-77
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• 2020

Airframe structure development of the 35 kg class 'Disaster and Public Safety Multicopter' UAV is described in this paper. To reduce the airframe weight, T-700 grade CFRP composite material was used, and the fuselage was designed with the semi-monocoque structure and plate installed with the control and communication devices designed in a sandwich structure. The specimen tests for the laminated plate and pipe were conducted to verify the strength and stiffness of the designed parts. The stacking sequence of composite materials was determined by the static strength and vibration analysis, and landing gear strut was designed by the nonlinear analysis with decent speed and ground clearance requirements. The static strength test was performed to evaluate the structural integrity and to verify the landing gear behavior.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.2
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• pp.84-89
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• 2021

Recently, shipyards are making many efforts to reduce the number of the mounted blocks by increasing the block size. This is to improve productivity and reduce related costs by minimizing block movement and shortening the building period. However, as the blocks become larger, the weight increases considerably. If the target block has a damage due to an unexpected accident during block lifting, it may seriously cause a problem of the reusability of the block. In this study, a large-sized block of the offshore structure weighing 480 tons was lifting with a total of seven sling belts, and one sling belt was broken while it was moving, resulting in a situation in which a part of the edge of the block collided with the ground. The aim of this paper is to verify the structural integrity of the block that directly collides with the ground in the form of free fall due to the sling breakage. Considering that the hook loads acting on several sling belts holding the block are redistributed when a sling belt is broken, the hook loads were recalculated at the angle just before the sling breakage. These loads were used to check the safety of the sling belts. In addition, FE analysis was performed by calculating the amount of impact from the free fall condition, obtaining the impact area by using Hertz's contact theory, and then applying the impact load to the area.

• Journal of Ginseng Research
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• v.43 no.1
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• pp.27-37
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• 2019

Background: The structural conversions in ginsenosides induced by steaming or heating or acidic condition could improve red ginseng bioactivities significantly. In this paper, the chemical transformations of red American ginseng from fresh Panax quinquefolium L. under steaming were investigated, and the possible mechanisms were discussed. Methods: A method with reversed-phase high-performance liquid chromatography coupled with linear ion trap mass spectrometry ($HPLC-MS^n$)-equipped electrospray ionization ion source was developed for structural analysis and quantitation of ginsenosides in dried and red American ginseng. Results: In total, 59 ginsenosides of protopanaxadiol, protopanaxatriol, oleanane, and ocotillol types were identified in American ginseng before and after steaming process by matching the molecular weight and/or comparing $MS^n$ fragmentation with that of standards and/or known published compounds, and some of them were determined to be disappeared or newly generated under different steaming time and temperature. The specific fragments of each aglycone-type ginsenosides were determined as well as aglycone hydrated and dehydrated ones. The mechanisms were deduced as hydrolysis, hydration, dehydration, and isomerization of neutral and acidic ginsenosides. Furthermore, the relative peak areas of detected compounds were calculated based on peak areas ratio. Conclusion: The multicomponent assessment of American ginseng was conducted by $HPLC-MS^n$. The result is expected to provide possibility for holistic evaluation of the processing procedures of red American ginseng and a scientific basis for the usage of American ginseng in prescription.

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.271-276
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• 2018

When the driver riding in a bicycle goes on board, the load of driver is shown differently according to the position loaded on the frame of bicycle. The load is applied most at the joint of bike frame and the load at the mid-part of frame is applied least than the other parts. So, the weight of frame is decreased as the part not applied with a lot of load is manufactured into the thin thickness. As the part applied with high load is manufactured into the thick thickness, it can be endured through this load. The configurations of general frame, double butted and triple butted were modelled by using CATIA program. The durabilities of each model due to the load of passenger were investigated by carrying the structural and fatigue analyses. As this study result investigated with the analysis program of ANSYS, the deformation of general frame happened most and that of triple butted became least. These simulation analysis data are intended to be used to design the actual bicycle frame in the most efficient way at design and manufacture.

• The Journal of the Korea Contents Association
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• v.18 no.11
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• pp.135-145
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• 2018

In online communities, users use comments to exchange their opinions and feelings on various subjects. Communication based on comments is quick and convenient, but sometimes this light-weight characteristic makes users use impolite and aggressive words, which leads to an online conflict. Therefore, it is important to analyze and classify users according to their characteristics in order to predict and take action for this kind of troubles. In this paper, we present several quantitative measures for describing the structures of comments trees based on the assumption that the user characteristics be observed as a form of some structural feature in comment trees of articles in which they posted comments. We examine the distribution of the proposed measures over article posters and commenters, and in addition, we show the effectiveness of the presented structural features by conducting experiments to classify users who have received warnings of the administrator from benign users.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.1-8
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• 2019

In the rapidly aging society, the number of wheelchair users is increasing steadily. On the other hand, it is almost impossible for a disabled person using a wheelchair to use express buses. Therefore, it is necessary to develop an express bus that can secure the rights of wheelchair users. For these special types of express buses, it is required to develop a special entrance and lift system. The development of a wheelchair entrance system for the express buses requires design modification, retrofit, and reinforcement of the bus frame. This study evaluated the structural integrity of an entrance system for wheelchair users using a finite element method. Torsional stiffness and modal analysis were performed through structural analysis. Through sensitivity analysis, optimization was performed to reduce the weight of the frame. These results on the wheelchair entrance system are expected to be utilized in the vehicle modification and welfare industries.

• Journal of Hydrogen and New Energy
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• v.29 no.6
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• pp.570-577
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• 2018

Composite pressure vessels made through filament winding are widely used in various fields. Numerous studies regarding composite pressure vessels have been conducted in the automotive industry to improve the space efficiency of trunks as well as the fuel efficiency. Compared with steel liquefied petroleum gas (LPG) vessels used in the conventional LPG vehicles, the use of type 4 composite pressure vessels has advantages in terms of reduction of the weight of vehicles. This study focused on development of type 4 composite pressure vessels that can be installed in the spare tire well. Those type 4 composite pressure vessels are designed with torispherical dome shapes instead of geodecis dome shapes because of the space limitation. To reduce deformation due to the stresses in the axial direction of the vessels, thereby securing the safety of the container, the reinforcing bar concept was applied. A structural analysis software, ABAQUS, confirmed the effect of the reinforcing bar on the axial deformation through the type 4 composite pressure vessel. As a result, the final winding angle of the composite layer was analyzed by applying $26^{\circ}/28^{\circ}/26^{\circ}/28^{\circ}/26^{\circ}/88^{\circ}$ The tensile stress was 939.2 MPa and the compressive stress was 249.3 MPa.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.51-55
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• 2019

The loss of safety for reservoirs brought about by climate change and facility aging leads to reservoir failures, which results in the loss of lives and property damage in downstream areas. Therefore, it is necessary to provide a Reservoir Failure Forecasting System for downstream residents to detect the early signs of failure (with sensors) in real-time and perform safety management to prevent and minimize possible damage. For the verification of established water level management criteria, 10 water level data up to reservoir capacity was selected. Weight factor and trend line were applied to dramatic increase section of water level in the 1 year period data. The results shows that water level criteria based on three even parts shows less than 7% of standard deviation and it is appropriate to verify management criteria.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.6
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• pp.98-105
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• 2019

In order to improve the fuel economy and dynamic behavior of automobiles, the weight reduction tendency of automobile parts is obvious. Also, in order to maximize assembly and maintenance convenience, various parts are integrated and modularized. Multi-piece methods require many manufacturing processes and become a factor of lowering the strength of parts. It is advantageous to overcome the disadvantages by integrally manufacturing to reduce the processing steps and ensure the strength of the parts. However, when it is necessary to process in a narrow space inside the part, it is impossible to process with the existing spindle. The angle head spindle is only a component of a machine tool, but it is a core part that requires high technology and is highly utilizable in products requiring high precision machining. Therefore, various and continuous studies needs for angle head spindles in areas such as vibration absorption, operational safety, excellent dimensional stability, and strength. In this paper, we propose an optimal design for angle head spindle by performing structural analysis and shape optimization for angle head spindle gear and case.