• Transactions of the Korean Society of Mechanical Engineers A
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• 제34권9호
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• pp.1161-1166
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• 2010

Tapered roller bearings are core components of rotating machine parts and are simultaneously subjected to axial and radial loads. Life-shortening effect was particularly evident in the case of tapered roller bearings used in the input and output shafts of transmission; this shortening of life was a result of excessive axial pre-load, which is common in the transmission assembly line. In this study, we derived an equation for evaluating the life of tapered roller bearings subjected to excessive pre-load by using accelerated life test data. The DOE(Design Of Experiment) method and FEA(Finite Element Analysis) was used for determining the condition for performing an accelerated life test. This equation for evaluating the service life of the bearings was derived by analyzing the Weibull distribution of the test results. Using the derived equation the life evaluated was 6-7 times longer than that evaluated by the conventional $L_{10}$ bearing-life equation. The results of this study will be helpful in predicting the life of tapered roller bearings subjected to excessive pre-load and in designing reliable rotating machines.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제16권10호
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• pp.7071-7077
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• 2015

In recently, the demand of cover-glass is increased because smart phone, tablet pc, and electrical device has become widely used. The display of mobile device is enlarged, so it is necessary to have a high strength against the external force such as contact or falling. In fabrication process of cover-glass, a grinding process is very important process to obtain high strength of glass. Conventional grinding process using a grinding wheel is caused such as a scratch, chipping, notch, and micro-crack on a surface. In this paper, polishing system using a abrasive film was developed for a grinding of mobile cover-glass. To evaluate structural stability of the designed system, finite element model of the polishing system is generated, and multi-body dynamic analysis of abrasive film polishing machine is proposed. As a result of the analysis, stress and displacement analysis of abrasive film polishing system are performed, and using laser displacement sensor, structural stability of abrasive film polishing system is confirmed by measuring displacement.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제16권10호
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• pp.6977-6984
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• 2015

It is faced with the necessity of multi roll forming process of the ball slide rail which is made by adding the separate manufacturing processes, piercing, bending, trimming, to the roll forming process of a continuous plastic deformation, to improve the quality. However, the vibration and noise of the press machine in this process leads to the quality degradation of slide rail manufactured in this process. In this study, the roll was designed considering the optimal strain rates by the roll forming program with finite element method. And to estimate the static stability of the multi process the Von-Mises stress and deformation on the press was calculated with a structural analysis program. Also, to avoid driving systems in the resonance region their natural frequencies in the 1st and 2nd mode were calculated through the modal analysis. To verify its dynamic stability improvement the magnitudes of noise and vibration in the existing and studied system were compared using a microphone and accelerometers. And the widths and surface roughnesses of the rails which had been produced in the existing and studied process were measured. Therefore, it is known that multi roll forming process is stable in the analytical and experimental study.

• Science of Emotion and Sensibility
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• 제14권1호
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• pp.93-100
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• 2011

Sonic branding is defined as creation and management of brand value by using sounds. Among various methods of sonic branding, sonic logo, i.e., brand’s acoustic identification element, is the most widely used form and usually combined with visual logo. Although sonic branding has become an increasingly important tool for marketers, little academic research has been done on this topic. The current study investigates neural responses to sonic branding using functional Magnetic Resonance Imaging (fMRI). Brain activity of 15 right-handed participants was monitored with 3T MRI machine, while they viewed sequentially presented pictures of brand logos (20 visual logos usually accompanied by sonic logos and 20 visual logos unaccompanied by sonic logos) without sound. Results showed that brain areas known to be associated with auditory imagery (including superior temporal gyrus, STG), showed greater activation for the visual logos usually accompanied by sonic logos compared to visual logos unaccompanied by sonic logos, although actual sound was not presented during scanning. The degree of familiarity participants have with the brand and its advertisements was correlated positively with signal strength in these areas.

• Informatization Policy
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• 제25권3호
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• pp.3-28
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• 2018

The purpose of this study is to analyze the research trends and present future research directions in the field of Cyber Physical System (CPS), a key element in the 4th Industrial Revolution, Industry 4.0, and Smart Manufacturing that are currently promoted as important innovation agenda both at home and abroad. In this study, (1) the concepts of industry 4.0, smart manufacturing and CPS are summarized; (2) analysis criteria of these fields are established; and 3) analysis results are presented and future research direction is proposed. 74 overseas and 8 domestic literature on manufacturing CPS from 2013 to 2017 are identified through 'Google Scholar Search'. Major results of the analysis are summarized as follows: (1) research on a common methodology and framework for the manufacturing CPS needs to be done based on the analysis of the existing methodologies and frameworks of various perspectives; (2) in order to improve the maturity of the manufacturing CPS, it is necessary to study actual deployment and operations of CPS, including the existing systems; (3) it is necessary to study the diagnostic methodology that can evaluate manufacturing CPS and suggest improvement strategy; and (4) as for the detailed model and tool, it is necessary to reinforce research on SCM production planning and human-machine collaboration while considering the characteristics of CPS.

• Journal of the Korean Institute of Intelligent Systems
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• 제20권6호
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• pp.884-889
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• 2010

Recently, a music genre classification has been studied. However, experts use different criteria to classify each of these classifications is difficult to derive accurate results. In addition, when the emergence of a new genre of music genre is a newly re-defined. Music as a genre rather than to separate search should be classified as emotional words. In this paper, the feelings of people on the basis of brightness and darkness tries to categorize music. The proposed classification system by applying VCM(Variance Considered Machines) is the contrast of the music. In this paper, we are using three kinds of musical characteristics. Based on surveys made throughout the learning, based on musical attributes(beat, timbre, note) was used to study in the VCM. VCM is classified by the trained compared with the results of the survey were analyzed. Note extraction using the MATLAB, sampled at regular intervals to share music via the FFT frequency analysis by the sector average is defined as representing the element extracted note by quantifying the height of the entire distribution was identified. Cumulative frequency distribution in the entire frequency rage, using the difference in Timbre and were quantified. VCM applied to these three characteristics with the experimental results by comparing the survey results to see the contrast of the music with a probability of 95.4% confirmed that the two separate.

• Korean Journal of Materials Research
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• 제8권8호
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• pp.744-750
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• 1998

Unlike common device, MEMS(micro-electro-mechanical system) device consists of very small mechanical structures which determine the performance of the device. Because of its small mechanical structure inside. MEMS device is very sensitive to thermal stress caused by CTE(coefficient of thermal expansion) mismatch between its components. Therefore, its characteristics are affected by material properties. process temperature. and dimensions of each layer such as chip, adhesive and substrate. In this study. we investigated the change of the thermal stress in the chip attached to a substrate. With computer-aided finite element method (FEM), the computer simulation of the thermal stress was conducted on variables such as bonding material, process temperature, bonding layer thickness and die size. The commercial simulation program, ABAQUS ver5.6, was used. Subsequently 3-layer test samples were fabricated, and their degree of bending were measured by 3-D coordinate measuring machine. The experimental results were in good agreement with the simulation results. This study shows that the bonding layer could be the source of stress or act as the buffer layer for stress according to its elastic modulus and CTE. Solder adhesive layer was the source of stress due to its high elastic modulus, therefore high compressive stress was developed in the chip. And the maximum tensile stress was developed in the adhesive layer. On the other hand, polymer adhesive layer with low elastic modulus acted as buffer layer, and resulted in lower compressive stress. The maximum tensile stress was developed in the substrate.

• The Journal of Bigdata
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• 제6권1호
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• pp.91-113
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• 2021

Despite the influence of real estate in the Korean asset market, it is not easy to predict market trends, and among them, apartments are not easy to predict because they are both residential spaces and contain investment properties. Factors affecting apartment prices vary and regional characteristics should also be considered. This study was conducted to compare the factors and characteristics that affect apartment prices in Seoul as a whole, 3 Gangnam districts, Nowon, Dobong, Gangbuk, Geumcheon, Gwanak and Guro districts and to understand the possibility of price prediction based on this. The analysis used machine learning algorithms such as neural networks, CHAID, linear regression, and random forests. The most important factor affecting the average selling price of all apartments in Seoul was the government's policy element, and easing policies such as easing transaction regulations and easing financial regulations were highly influential. In the case of the three Gangnam districts, the policy influence was low, and in the case of Gangnam-gu District, housing supply was the most important factor. On the other hand, 6 mid-lower-level districts saw government policies act as important variables and were commonly influenced by financial regulatory policies.

• The Journal of the Acoustical Society of Korea
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• 제40권4호
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• pp.330-336
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• 2021

In bistatic sonar operation, the scattering strength of a sonar target is characterized by the probe signal frequency, the aspect angle and the bistatic angle. Therefore, the target detection and identification performance of the bistatic sonar may vary depending on how the positions of the target, sound source, and receiver are changed during sonar operation. In this study, it was evaluated which variable is advantageous to change by comparing the target identification performance between the case of changing the aspect angle and the case of changing the bistatic angle during the operation. A scenario of identifying a hollow sphere and a cylinder was assumed, and performance was compared by classifying two targets with a support vector machine and comparing their accuracy using a finite element method-based acoustic scattering simulation. As a result of comparison, using the scattering strength defined by the frequency and the bistatic angle with the aspect angle fixed showed superior average classification accuracy. It means that moving the receiver to change the bistatic angle is more effective than moving the sound source to change the aspect angle for target identification.

• Journal of the Korea Convergence Society
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• 제9권12호
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• pp.175-180
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• 2018

In this study, CFRP was manufactured with the laminate angle of $45^{\circ}$. The specimen of TDCB bonded with the adhesive for structure was designed by CATIA and the analysis was progressed by using the finite element analysis program of ANSYS. This study model was designed on the basis of British industry and ISO standard and the configuration factor(m) was established with variable according to the angle of model configuration. As the study result of this paper, the maximum deformations at the specimens with the tapered angles of $4^{\circ}$ and $8^{\circ}$ become most as 12.628 mm and least as 12.352mm respectively. Also, the maximum equivalent stresses at the specimens with the tapered angles of $6^{\circ}$ and $8^{\circ}$ become most as 9210.3 MPa and least as 4800.5 MPa respectively. The damage data of TDCB structure with the laminate angle which was manufactured with CFRP could be secured through this study result. As the damage data of TDCB structure bonded with CFRP obtained on the basis of this study result are utilized, the esthetic sense can be shown by being grafted onto the machine or structure at real life.