• Journal of Korea Foundry Society
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• v.42 no.4
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• pp.218-225
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• 2022

For hydrogen-vehicle applications (air pressure control valve housing, APCVH), an investigation was conducted to determine how micro-defects in a high- pressure die-casted Al alloy (industrial code: ALDC12) could be controlled by means of a post-treatment using an organic-based impregnation solution in order to improve the air- tightness of the die-casted Al sample. Two different impregnation solutions were proposed and its test results were compared to a imported product from Japan with respect to the processing variables used. A structural investigation of the components under study was conducted by means of computer tomography and 3D X-ray micro-CT. These observations revealed that the use of the impregnation treatment to seal micro-defects led to highly significant and beneficial changes which were attributed mainly to interconnections among inherent micro-pores. A leak test after impregnation revealed that the performance improvement rate of the die-casted Al sample was ~70% for INNO-01. Therefore, the developed impregnation solutions offer an effective strategy to control the micro-defects found in various vehicle parts via die-casting.

• The Journal of the Convergence on Culture Technology
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• v.7 no.2
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• pp.207-216
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• 2021

This study was conducted on 315 women in their 20s and 40s living in Changwon, South Gyeongsang Province, and recorded in a self-recorded format using the questionnaire survey method. In this study, the skin type according to the skin condition was not applied for 30 minutes after washing and checking the cheek area through the examination method to distinguish it by intelligence, neutral, dryness and boredom to see the interaction with each condition. The X2-test was conducted to find out the relevance between each factor and the data processing was done using PC/SAS. We reached at following conclusions. We can find some connections between skin condition and age, job, marriage by statistics(p<0.01). Each value of X2-TEST was 42.961(p<0.001) and 7.345(p<0.05). The pimples are shown after stress on cheek, chin and around neck easily. We also find some connections between skin trouble reaction and the beginning of pimple shown time(p<0.01).

• Journal of People, Plants, and Environment
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• v.24 no.4
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• pp.355-363
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• 2021

Background and objective: This study was conducted on Forsythia velutina, a special plant, in Gyeongsangnam-do Arboretum under the Gyeongsangnam-do Forest Environment Research Institute, which is located in the southern part of Korea. Methods: The research aimed to analyze the flowering characteristics of the plant by calculating the optimal temperature and humidity according to the flowering time and flowering period for 8 years from 2010 to 2017 in order to provide basic data for bioclimate studies of endemic plants. Results: It was observed that the Forsythia velutina showed a life cycle from mid-March and to mid-November. Average growth period was 243 (± 6.5) days. In testing the reliability of a single variable according to the meteorological factors, the Cronbach's Alpha was 0.701, which indicates that the findings were relatively reliable. The average date of flowering was March 16 (SD = 5.8) and the average date on which blossoms fall was March 29 (SD = 5.2). A substantial difference in flowering period was observed from year to year 11 to 23 days, with an average of 16 days (± 4.7). The temperature and humidity in February to March, which affect the flowering, were 2.9-5.5℃, and 66.5-73.0%, respectively, and showed differences every year. Conclusion: The correlation between flowering time and meteorological factors was positive, and the highest daily temperature and average daily temperature had the highest significance. When establishing basic data on plant species for the conservation of endemic plants, the changes in life cycle events and weather conditions are identified. It is believed that it will be helpful in establishing a conservation strategy for the plant species in the future.

• Journal of the Korea Society of Computer and Information
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• v.26 no.12
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• pp.69-75
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• 2021

Recently, deep learning, which is the most used in the field of artificial intelligence, has a structure that is gradually becoming larger and more complex. As the deep learning model grows, a large amount of data is required to learn it, but there are cases in which it is difficult to integrate and learn the data because the data is distributed among several owners and security issues. In that situation we conducted parallel learning for each users that own data and then studied how to integrate it. For this, distributed learning was performed for each owner assuming the security situation as V-environment and H-environment, and the results of distributed learning were integrated using Average, Max, and AbsMax. As a result of applying this to the mnist-fashion data, it was confirmed that there was no significant difference from the results obtained by integrating the data in the V-environment in terms of accuracy. In the H-environment, although there was a difference, meaningful results were obtained.

• Communications of Mathematical Education
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• v.36 no.4
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• pp.487-509
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• 2022

The purpose of this study is to analyze classroom discourse in the math classroom of middle school in China, which has a unique math classroom background of entrance examination for high school. To this end, this study analyzed teacher question statistics and episodes by teacher question type as starting speech in mathematics classroom discourse, and five IRF subtypes were especially identified by class discourse structure analysis. The data were analyzed focusing on a total of 15 transcripts of math classes recorded by three math teachers at H School in Guiyang, Guizhou Province, China, and written interviews of teachers. According to the results of this study, an average of 20 teacher questions were observed for each class, and the teacher question type was classified into confirmation question (understanding confirmation question, explanation request question, and double check question) and information question (information presentation question). In addition, according to classroom discourse analysis, the IRF discourse structure was divided into fragmentary evaluation, evaluation+reason, evidence of explanation, evaluation+student response re-statement, guidance on other thoughts or solutions, and student answer correction or teacher opinion presentation.

• Journal of the Korea Computer Graphics Society
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• v.28 no.3
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• pp.45-54
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• 2022

Image depth estimation is a technology that is the basis of various image analysis. As analysis methods using deep learning models emerge, studies using deep learning in image depth estimation are being actively conducted. Currently, most deep learning-based depth estimation models are being trained with clean and ideal images. However, due to the lack of data on adverse conditions such as haze or fog, the depth estimation may not work well in such an environment. It is hard to sufficiently secure an image in these environments, and in particular, obtaining non-homogeneous haze data is a very difficult problem. In order to solve this problem, in this study, we propose a method of synthesizing non-homogeneous haze images and a learning method for a monocular depth estimation deep learning model using this method. Considering that haze mainly occurs outdoors, datasets mainly containing outdoor images are constructed. Experiment results show that the model with the proposed method is good at estimating depth in both synthesized and real haze data.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.441-448
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• 2021

The purpose of this study were to investigate knowledge, awareness, and moral sensitivity, performance of standard precaution, and to identify influencing factors on performance of standard precaution of nursing students. The subjects of this study were completed by 201 nursing students from 2 colleges in D City. Data were collected from December 2 to 20, 2019. Data were analyzed using the t-test, the ANOVA, the Pearson correlation coefficient, and multiple regression analysis by SPSS ver. 21.0. There were significant positive correlations among knowledge of standard precaution, awareness of standard precaution, and moral sensitivity on performance of standard precaution. The factors influencing performance of standard precaution of the study subjects were awareness of standard precaution(β=.78, p<.001), and the explanatory power of these variables was 60.5%. The development of awareness of standard precaution education program that focuses awareness of standard precaution change is needed.

• Journal of the Korea Society of Computer and Information
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• v.27 no.10
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• pp.115-121
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• 2022

In this paper, we analyze trends in the use of mobile forensic technology, focusing on cases where mobile forensics are used, and we predict the development of future mobile forensics technology using linear regression used in future prediction models. For the current status and outlook analysis, we extracted a total of 8 variables by analyzing 1,397 domestic and foreign mobile forensics-related cases and newspaper articles. We analyzed the prospects for each variable using the year of occurrence as an independent variable, seven variables such as text (text message usage information), communication information (cell phone communication information), Internet usage information, messenger usage information, stored files, GPS, and others as dependent variables. As a result of the analysis, among various aspects of the use of mobile devices, the use of Internet usage information, messenger usage information, and data stored in mobile devices is expected to increase. Therefore, it is expected that continuous research on technologies that can effectively extract and analyze characteristic information of mobile devices such as file systems, the Internet, and messengers will be needed As mobile devices increase performance and utilization in the future and security technology.

• Journal of the Society of Disaster Information
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• v.18 no.4
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• pp.795-805
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• 2022

Purpose: The purpose of this paper is to examine the recently rising number of foreign drug offenders in Korea and suggest improvement measures for the Korean drug policy. Method: This paper analyzed the preceding research, statistical data, etc., on related fields and referred to overseas cases to suggest improvement measures. Result: The foreign population living in Korea increased in 2000s, and the foreign drug offender cases are increasing accordingly. The survey on foreign drug offenses showed that the case of foreign drug offender is higher than the case of Korean drug offenders by 1.2 to 3.3 times. In 2021, the foreign drug offender cases increased by 6.5 times compared to 2012. Especially, the number of psychoactive drug-related drug offenses increased dramatically. The drug smuggling also remarkably increased starting from 2016 as some people earned a lot of money from smuggling the drugs Conclusion: To cope with the foreign drug offenders effectively, this paper suggested intensive monitoring of the foreign drug offenders and weighting on the drug offenders depending on their home country to intensify the entry standards on foreigners who are likely to smuggle drugs.

• Journal of the Korea Society of Computer and Information
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• v.28 no.8
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• pp.1-10
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• 2023

Recently, NAND flash memories have replaced magnetic disks due to non-volatility, high capacity and high resistance, in various computer systems but it has disadvantages which are the limited lifespan and imbalanced operation latency. Therefore, many page replacement policies have been studied to overcome the disadvantages of NAND flash memories. Although it is clear that these policies reflect execution characteristics of various environments and applications, researches on the foundation-policy decision for disk buffer management are insufficient. Thus, in this paper, we propose a foundation-policy recommendation model, called FRM for effectively utilizing NAND flash memories. FRM proposes a suitable page replacement policy by classifying and analyzing characteristics of workloads through machine learning. As an implementation case, we introduce FRM with a disk buffer management policy and in experiment results, prediction accuracy and weighted average of FRM shows 92.85% and 88.97%, by training dataset and validation dataset for foundation disk buffer management policy, respectively.