• Tunnel and Underground Space
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• v.28 no.6
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• pp.569-583
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• 2018

The purpose of this study is to identify the collapse characteristics by analyzing various factors causing collapse based on field survey and existing data on rock slopes occurring in the construction of roads and industrial complexes in Gyeongsangnam - do area. In the case of the slope where the slope has been directly surveyed, the analysis of the collapse characteristics can be used for the prediction and prevention of slope failure through the continuous collection of the slope data, database construction, management and analysis. The evaluation items used in the collapse characteristics of slope were selected among the items that can be regarded as objective evaluation items among the overlapping factors by comparing the evaluation items frequently used for the evaluation of the existing slope stability among various factors. The type of destruction of the rock slope depends on the type of carcass of the bedrock, such as planar fracture, wedge fracture, onho fracture, and conduction fracture, which are different from each other. And the slope stability analysis should be performed accordingly.

• Journal of Digital Convergence
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• v.17 no.2
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• pp.405-412
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• 2019

This paper aims to identify differences between the perception of the fourth industrial revolution of the disabled who use the IL center or the disabled in the community and its workers. It surveyed 178 disabled users and 173 workers at eight centers of the handicapped in Busan and South Gyeongsang-do and conducted an analysis on their interests in the fourth industry, awareness of the latest technology, and prediction of changes in the disabled welfare center. Although worker's interest in the fourth industry was higher than their users, their perception of the degree of preparation by the disabled welfare centers indicated that the worker's level of future institutional readiness was lower than that of the users. The results will be used to help set directions for future guidelines and plans for the welfare of the disabled.

• Korean Journal of Materials Research
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• v.28 no.11
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• pp.680-684
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• 2018

We investigate the effect of light intensity and wavelength of a solar cell device using photoconductive atomic force microscopy(PC-AFM). A $POCl_3$ diffusion doping process is used to produce a p-n junction solar cell device based on a polySi wafer, and the electrical properties of prepared solar cells are measured using a solar cell simulator system. The measured open circuit voltage($V_{oc}$) is 0.59 V and the short circuit current($I_{sc}$) is 48.5 mA. Moreover, the values of the fill factors and efficiencies of the devices are 0.7 and approximately 13.6 %, respectively. In addition, PC-AFM, a recent notable method for nano-scale characterization of photovoltaic elements, is used for direct measurements of photoelectric characteristics in limited areas instead of large areas. The effects of changes in the intensity and wavelength of light shining on the element on the photoelectric characteristics are observed. Results obtained through PC-AFM are compared with the electric/optical characteristics data obtained through a solar simulator. The voltage($V_{PC-AFM}$) at which the current is 0 A in the I-V characteristic curves increases sharply up to $18W/m^2$, peaking and slowly falling as light intensity increases. Here, $V_{PC-AFM}$ at $18W/m^2$ is 0.29 V, which corresponds to 59 % of the average $V_{oc}$ value, as measured with the solar simulator. Furthermore, while the light wavelength increases from 300 nm to 1,100 nm, the external quantum efficiency(EQE) and results from PC-AFM show similar trends at the macro scale but reveal different results in several sections, indicating the need for detailed analysis and improvement in the future.

• Korean Journal of Remote Sensing
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• v.34 no.6_1
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• pp.1131-1142
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• 2018

The autonomous vehicles are being developed and operated widely because of the advantages of reducing the traffic accident and saving time and cost for driving. The vehicle localization is an essential component for autonomous vehicle operation. In this paper, localization algorithm based on sensor fusion is developed for cost-effective localization using in-vehicle sensors, GNSS, an image sensor and reference images that made in advance. Information of the reference images can overcome the limitation of the low positioning accuracy that occurs when only the sensor information is used. And it also can acquire estimated result of stable position even if the car is located in the satellite signal blockage area. The particle filter is used for sensor fusion that can reflect various probability density distributions of individual sensors. For evaluating the performance of the algorithm, a data acquisition system was built and the driving data and the reference image data were acquired. Finally, we can verify that the vehicle positioning can be performed with an accuracy of about 0.7 m when the route image and the reference image information are integrated with the route path having a relatively large error by the satellite sensor.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.3
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• pp.173-181
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• 2019

To estimate probabilistic distribution function from experimental data, kernel density estimation(KDE) is mostly used in cases when data is insufficient. The estimated distribution using KDE depends on bandwidth selectors that smoothen or overfit a kernel estimator to experimental data. In this study, various bandwidth selectors such as the Silverman's rule of thumb, rule using adaptive estimates, and oversmoothing rule, were compared for accuracy and conservativeness. For this, statistical simulations were carried out using assumed true models including unimodal and multimodal distributions, and, accuracies and conservativeness of estimating distribution functions were compared according to various data. In addition, it was verified how the estimated distributions using KDE with different bandwidth selectors affect reliability analysis results through simple reliability examples.

• Composites Research
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• v.31 no.6
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• pp.299-303
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• 2018

In order to improve the interfacial bonding force and reaction polymerization degree of the carbon fiber reinforced nylon 6 composite material, the surface of the existing epoxy-sizing carbon fiber was desized to remove the epoxy and treated with urethane, nylon and phenoxy sizing agent, was observed. The interfacial bond strength of the resized carbon fiber was confirmed by IFSS (Interfacial Shear Strength) and the fracture surface was observed by scanning electron microscope. The results showed that the interfacial bonding strength of the carbon fiber treated with nylon and phenoxy sizing agents was higher than that of urethane - based sizing. It has been found that the urethane - type resizing carbon fiber has lower interfacial bonding strength than the conventional epoxy - sizing carbon fiber. This result shows that the interfacial bonding between carbon fiber and nylon 6 is improved by removing low activity and smoothness of existing carbon fiber.

• Journal of the Korea Convergence Society
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• v.12 no.5
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• pp.51-60
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• 2021

This study is a descriptive research conducted to identify smartphone addiction and influencing factors of high grades of elementary school students. The subjects were 294 elementary school students in the 4th, 5th, and 6th grades at 31 regional children's centers located in C city. Data were collected from May 13, 2019 to June 10, 2019. For data analysis, frequency analysis, 𝑥²-test, and logistic regression analysis were performed using SPSS Win 23.0 program. The result of the study were 16% in the addiction risk group and 84.0% in the general group. Factors influencing smartphone addiction were smartphone usage time on weekdays(95% CI: 1.263~827.849, p=.036), and main usage time of smartphone(95% CI: 1.028~29.574, p=.046). Therefore, in order to prevent smartphone addiction of high grade of elementary school, it is necessary to develop a smartphone addiction prevention education or nursing intervention program by identifying usage time and main usage time of smartphone.

• Korean Journal of Plant Resources
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• v.32 no.5
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• pp.559-564
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• 2019

Cyrtomium yamamotoi Tagawa is an unrecorded species of perennial Pteridophyta that belongs to the genus Cyrtomium of Dryopteriaceae. It is known as native to Taiwan, China and Japan, but we found it in Jeju-si, Jeju-do and Haenam-gun, Jeollanam-do, Republic of Korea in 2018. This species is very similar to C. fortunei J.Sm. having characters such as 1 pinnate compound leaves, globular indusium, but distinguished from the latter by its lanceolate or lanceolate-ovate shaped lateral pinnates of less than 12 pairs, bicolor indusium with dark brown or blackish in center, and margin incised teeth. Here, we provide its description, photographs and a key of related taxa in Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.507-513
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• 2021

This study examined the final stop position and posture of both vehicles, the damaged part of the vehicle, the road surface, the specifications of the vehicle, and the angle of impact, centering on the case of a collision in which no surface trace was found. As a result of the simulation, the impact velocity of an SM5 and Lexus was 131 km/h and 74 km/h, respectively, and the impact angle of the SM5 and Lexus was 0.91° and -161.07°, respectively. The cause of the accident was that the SM5 passed through the intersection exceeding the maximum speed limit of 61 km/h and entered the Lexus' left turn lane. Lexus collided during the evacuation to avoid the collision. The collision trajectory error rate of the simulation was approximately 1.4%. Of the subjective experience of accident investigators, the collision dynamics and vehicle engineering aspects and simulations were actively utilized to provide close-to-fact cause identification.

• The Journal of Korean Philosophical History
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• no.42
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• pp.9-37
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• 2014

This article is to review academic aspects of Iljae Lee Hang through Toegye Lee Hwang's comments. Iljae Lee Hang (一齋 李恒: 1499~1576) is a representative Neo-Confucian scholar in Honam area in 16th century. His Sung Confucianism was known to Toegye Lee Hwang by Gobong Gi Dae Seung and consequentially received attention from academic world. Lee Hang's Sung Confucianism, however, has hardly drawn attention since 17th century due to Lee Hwang's negative assessment. Impeaching Lee Hang's academic attitude and methods, Lee Hwang evaluated him as having many problems. Lee Hwang criticized that Lee Hang studied Neo-Confucianism with no great effort and he was so much confident to say 'Logic of the world does not deviate from this' based on Chengzi and Zhuzi's saying which was only appealing to his ideas. Lee Hang actually cited theories of Chengzi and Zhuzi and stressed self-complacency when necessary, which therefore made him fail to exhibit consistency. Iljae partly brought Lee Hwang's criticism upon himself. Lee Hwang's negative assessment is not to be literally accepted but his assessment is helpful indeed to critically examine Lee Hang's Neo-Confucianism.