• Journal of Auto-vehicle Safety Association
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• v.12 no.3
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• pp.34-42
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• 2020

ADAS (Advanced Driver Assistance Systems) uses sensors such as camera, radar, lidar and GPS (Global Positioning System). Among these sensors, the camera has many advantages compared with other sensors. The reason is that it is cheap, easy to use and can identify objects. In this paper, therefore, a theoretical formula was proposed to obtain the distance from the vehicle's front wheel to the lane using a monocular camera. And the validity of the theoretical formula was verified through the actual vehicle test. The results of the actual vehicle test in scenario 4 resulted in a maximum error of 0.21 m. The reason is that it is difficult to detect the lane in the curved road, and it is judged that errors occurred due to the occurrence of significant yaw rates. The maximum error occurred in curve road condition, but the error decreased after lane return. Therefore, the proposed theoretical formula makes it possible to assess the safety of the LKA system.

• Journal of Technologic Dentistry
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• v.34 no.4
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• pp.447-455
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• 2012

Purpose: This study was to investigate oral hygiene knowledge and the actual condition of oral care for the students in the public health and non-public health Departments. Methods: The survey sample consisted of 262 randomly selected students. 197 of them are public health-related students and 65 are non-public health-related students. The questionnaires used in this study consisted of 4 items for general information, oral health status of 2 items, 5 items for Oral hygiene knowledge and actual condition of oral care of 5 items. Collected data were analyzed by Frequency Analysis t-test and Crosstabs using SPSS(Statistical Package for Social Sciences) Win 19.0 statistics program. Results: Regarding general characteristics of the subjects, there were 53.8% of first-year student, 26.0% of second-year student and 20.2% of third-year student among 52.3% of males and 47.7% of females. The subjects received less than "100,000" won(13.0%), "100,000-190,000" won (5.0%), "200,000-290,000" won(30.9%), "300,000-390,000" won (33.2%) and more than "400,000" won(17.9%) a month for an allowance. The subjects had 'none' (44.3%), '1'(6.5%), '2'(12.6%), '3'(5.0%), '4'(5.3%), 'more than' 5(0.8%) of dental caries and 'do not know' were 25.6%. The numbers of dental prosthetics were 'no' (35.5%), '1'(13.7%), '2'(17.2%), '3'(10.3%), '4'(11.5%), and 'more than 5'(11.8%). The public health students(84.8%) had a higher positive response rate than the non-public health students(66.2%). The public health students(80.2%) had a higher negative response rate than the non-public health students(78.5%) in the result of onset of gum disease pain awareness. The non-public health students(65.5%) had a higher negative response rate than the public health students(68.3%)) in the result of heredity of gum disease. The t-test showed that public health-related department students(M=8.264, SD=0.821) had more knowledge about oral hygiene than non-public health-related department students(M=8.015, SD=1.082). 'do not use' in the oral care products except toothpaste and toothbrush showed that public health-related department students(60.4%) use the products more than non-public health-related department students(66.2%). Conclusion: In this study, public health-related department students had higher oral hygiene knowledge and actual condition of oral care compared to non-public health-related students, but low in practical action. Due to the lower level of dental care products use in non-public health-related department, a continuous oral care education program is required.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.3
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• pp.141-147
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• 2018

In a time when product development cycles are getting shorter and shorter, many companies are making efforts to develop products with high reliability in a short period of time, accelerated life test is widely used as a method to quickly evaluate reliability. Accelerated life test reduces the test life or the life of the product from the observed data by shortening the lifetime of the product or abruptly lowering the performance under the worse condition than the actual condition in order to shorten the test cost or the test time. In this paper, BL3640A-06P+RB35, DC12V model, which is used in the support device of an automatic rotation type digital signage, which display various information such as textures and images on a display screen in a public place or a commercial space, BLDC motors were subjected to a constant stress test and at the rotational speed of 1rpm, $180^{\circ}$ rotation and reverse rotation under actual use conditions, the stress was imposed on the rotating speed of 2rpm and the weight of the actual installed product from 22.2kgf to 10kgf were installed. The lifetime of the actual use environment condition is 23,545 hours and the rotation speed is accelerated. The life time of the acceleration condition with the additional weight is 1,380 hours. The acceleration factor is calculated as 17.06, the one year guarantee test day is 235 days to 14 days, of the period from 470 days to 28 days, and the third year from 704 days to 42 days. The test date of the BLDC motor was tested on the shortened test date, and the rotational speed and the current value were measured. It is found that there is no defect even if it operates as the test date corresponding to the specified one year warranty period and the 3 year accelerated life test which is experimented. Using the statistical technique of the regression analysis the expected time for the motor to defect to #4 samples was 20 years.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.142-147
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• 2004

The flow in the LOX manifold of liquid rocket has been investigated using a CAE technique with an objective of economical modeling of injection holes in order to reduce the overall computational cost of flow analysis during the optimal rocket design procedure. The computational geometry is very close to that of the actual rocket design and the flow condition through the injection holes resembles that in the actual manifold of the liquid rocket. The result shows that the flow in the plane just above the injection holes is not uniformly distributed in terms of pressure and mass flow rate and this is attributed to the large-scale flow patterns present the LOX manifold. Thus, the flow physics should be understood correctly before making any attempt to model the injection holes. In the present study, several boundary conditions which were designed to effectively replace the presence of injection holes have been tested and it was found that a simple modeling can be possible by mimicking the actual geometry of the injection holes. By using this simple injection hole modeling, it was able to obtain about 30% reduction in computational cost but it was still able to reproduce the flow patterns correctly. Also the flow has been analyzed after incorporating a couple of different types of pre-distributors in LOX manifold and the effect of those will be discussed.

• Corrosion Science and Technology
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• v.17 no.5
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• pp.211-217
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• 2018

Natural degradation of grounding-electrode in soil environment should be monitored for several decades to predict the lifetime of the grounding electrode for efficient application and management. However, long-term studies for such electrodes have many practical limitations. The conventional accelerated corrosion test is unsuitable for such studies because simulated soil corrosion process cannot represent the actual soil environment. A preliminary experiment of accelerated corrosion test was conducted using existing test standards. The accelerated corrosion test that reflects the actual soil environment has been developed to evaluate corrosion performances of grounding-electrodes in a short period. Several test conditions with different chamber temperatures and salt spray were used to imitate actual field conditions based on ASTM B162, ASTM B117, and ISO 14993 standards. Accelerated degradation specimens of copper-bonded electrodes were made by the facile method and their corrosion performances were investigated. Their corrosion rates were calculated to $0.042{\mu}m/day$, $0.316{\mu}m/day$, and $0.11{\mu}m/day$, respectively. These results indicate that accelerated deterioration of grounding materials can be determined in a short period by using cyclic test condition with salt spray temperature of $50^{\circ}C$.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.70-73
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• 2000

In this paper we conducted research about the speaker's acoustic characteristics by the condition of the duct. It is expanding the bass ton play frequency as interfere two frequencies each other which originate from the speaker's back and front side using duct as attach the duct of round shaped or square at the encloser. This is not making of bass ton range using interference,. The structure of the duct which using the experiment is round shape. And we confirmed that can expand the limit of bass ton play as compare the actual experimental wave that after simulation of play frequency range as lenth change

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.438-446
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• 1999

Crop minimization of the top and bottom ends of hot rolled plate, in a plate, in a plate mill, has been investigated. The existing model to determine the edging pattern at the finishing rolling pass was not reasonable to get high width accuracy and rolling yields. New models including width prediction have been formulated by using neural network model of back propagation learning algorithm and statistical analysis based on the actual production rolling data to give the optimal pattern for minimizing trimming loss. Using these models, at a given rolling condition of broadside pass and finishing pass and the permissible condition of width variation, it was possible to minimize crip at the top and bottom ends according to optimum procedure in plate mill. An application to improve the plan view pattern reduced width variation by 23% and crop length by 30% on average with an effective fishtail crop shape.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.2
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• pp.401-406
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• 2016

Elevator is very important transportation facility of modern society. But there have been frequent elevator accidents recently. In the view of safety management of elevator, the corresponding study must be done since accidents related elevator include not only actual accident but also possible accident in order to protect user from danger. A 3D design was developed using SolidWorks and behavior analysis using FEM Code.

• Journal of Power System Engineering
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• v.14 no.2
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• pp.40-47
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• 2010

This paper proposes a fault detection system to detect the strip rupture in six-high stand Cold Rolling Mills based on transient current signal of an electrical motor. For this work, signal smoothing technique is used to highlight precise feature between normal and fault condition. Subtracting the smoothed signal from the original signal gives the residuals that contains the information related to the normal or faulty condition. Using residual signal, discrete wavelet transform is performed and acquire the signal presenting fault feature well. Also, feature extraction and classification are executed by using PCA, KPCA and SVM. The actual data is acquired from POSCO for validating the proposed method.

• Journal of The Korea Institute of Healthcare Architecture
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• v.16 no.1
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• pp.7-16
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• 2010

The cultural assets of the palaces royal tombs remains institution expanded the convenient facilities for the disabled that can help the disabled to watch, to propel the convenient facility expanding business according to the condition of each facility. However, there has been limitations for the disabled facility users in viewing the cultural assets, as the facilities were not installed or were not installed properly. Due to the uniform installation of the convenient facilities that did not consider the features of the cultural assets, the conservation value of the cultural assets have been depreciated and the convenient use standards of the facility users such as the disabled were simultaneously unsatisfactory. Thus, this study maintains the pre-existing value of the palaces royal tombs remains institution that is the Korean indigenous traditional heritage, and uses a part of the improvement model development study on the palaces royal tombs remains institution of the disabled convenience enhancement to understand the current convenient facility installation and relevant services to find the restricted factors in using the facilities and the main problems. The problems were categorized into 13 types of questions, using the repeated problems occurred within the investigated facilities to look at the actual condition of the facilities, which showed that the facilities were in adequate in the aspects of convenient facility installation and relevant service.