• Ecology and Resilient Infrastructure
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• v.4 no.4
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• pp.226-236
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• 2017

In this study, we aimed to analyze the characteristics of water quality variation at Kyeongan Stream for a decade and to investigate by the flow-loading equation. The correlation analysis of water quality parameters and the influence factors were examined by statistical analysis. The characteristics of water quality variation showed that the fluctuations in $BOD_5$, $COD_{Mn}$ and TOC were repeated from year to year. TN and TP were decreased by year. By the flow-loading equation, the concentrations of $BOD_5$, $COD_{Mn}$, TOC and TN were decreased when the flow rate was on the rise. However, the flow did not affect the concentration of TP. According to correlation analysis, $BOD_5$ was highly correlated with $COD_{Mn}$ and TOC with the correlation coefficients of 0.890 (p<0.01) and 0.721 (p<0.01). The result of factor analysis, we identified that the water quality in Kyeongan Stream has been highly influenced by the organic matter index, followed by nitrogenous substance depending on the seasonal variations and the influx of suspended solid in accordance with the increase of flow.

• Analytical Science and Technology
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• v.30 no.4
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• pp.213-219
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• 2017

Polyalkylsiloxane has been spotlighted in pressure-sensitive adhesive (PSA) application due to excellent physical properties and good biocompatibility. Thermal behaviour of polyalkylsiloxane mixtures, such as thermal stability and heat flow, were studied using TG-DTA during catalytic hydrosilation. To understand reaction kinetics of cross-linking, catalytic hydrosilation of polyalkylsiloxane was monitored using variable temperature nuclear magnetic resonance (VT-NMR) as increased temperature. The formation of cross-linking bond $Si-CH_2-CH_2-Si$ was directly observed using distortionless enhanced by polarization transfer (DEPT) technique. Successfully polyalkylsiloxane PSA samples exhibited excellent adhesion properties by cross-linking reaction.

• Safety and Health at Work
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• v.8 no.3
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• pp.318-321
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• 2017

This commentary presents the regulatory backgrounds and development of the national proficiency testing (PT) scheme on asbestos analysis in the Republic of Korea. Since 2009, under the amended Occupational Safety and Health Act, the survey of asbestos in buildings and clearance test of asbestos removal works have been mandated to be carried out by the laboratories designated by the Ministry of Employment and Labor (MOEL) in the Republic of Korea. To assess the performance of asbestos laboratories, a PT scheme on asbestos analysis was launched by the Korea Occupational Safety and Health Agency (KOSHA) on behalf of the MOEL in 2007. Participating laboratories are evaluated once a year for fiber counting and bulk asbestos analysis by phase contrast microscopy and polarized light microscopy, respectively. Currently, the number of laboratory enrollments is > 200, and the percentage of passed laboratories is > 90. The current status and several significant changes in operation, sample preparations, and statistics of assigning the reference values of the KOSHA PT scheme on asbestos analysis are presented. Critical retrospect based on the experiences of operating the KOSHA PT scheme suggests considerations for developing a new national PT scheme for asbestos analysis.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.8
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• pp.35-41
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• 2010

White Etching Layer(WEL) is a phenomenon that occurs on the surface of rail due to wheel/rail interactions such as excessive braking and acceleration. Rolling Contact Fatigue(RCF) cracks on the surface of rail have been found to be associated with WEL. In this study, we have investigated RCF damages of white etching layer using twin disc testing and fatigue analysis. These tests consist of wheel flat tests and rolling contact fatigue tests. WEL has been simulated by wheel flat test. It has been founded that the WEL with a bright featureless contrast is formed on the surface of specimen by etching. Rolling contact fatigue test was conducted by using flat specimens with the WEL generated by the wheel flat test. It has been observed that two types of cracks occur within the specimen. The contact fatigue test was simulated in 2D elastic-plastic FE simulations. Based on loading cycles obtained from the finite element analysis, the fatigue life analysis according to the thickness variation of WEL was carried out. The longest fatigue life was observed from the thickness of 20um.

• Child Health Nursing Research
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• v.27 no.3
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• pp.201-210
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• 2021

Purpose: This study analyzed research trends related to childhood and adolescent cancer survivors (CACS) using word co-occurrence network analysis on studies registered in the Korean Citation Index (KCI). Methods: This word co-occurrence network analysis study explored major research trends by constructing a network based on relationships between keywords (semantic morphemes) in the abstracts of published articles. Research articles published in the KCI over the past 10 years were collected using the Biblio Data Collector tool included in the NetMiner Program (version 4), using "cancer survivors", "adolescent", and "child" as the main search terms. After pre-processing, analyses were conducted on centrality (degree and eigenvector), cohesion (community), and topic modeling. Results: For centrality, the top 10 keywords included "treatment", "factor", "intervention", "group", "radiotherapy", "health", "risk", "measurement", "outcome", and "quality of life". In terms of cohesion and topic analysis, three categories were identified as the major research trends: "treatment and complications", "adaptation and support needs", and "management and quality of life". Conclusion: The keywords from the three main categories reflected interdisciplinary identification. Many studies on adaptation and support needs were identified in our analysis of nursing literature. Further research on managing and evaluating the quality of life among CACS must also be conducted.

• Journal of the Korean Chemical Society
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• v.39 no.3
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• pp.224-229
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• 1995

• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.737-741
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• 1991

• Proceedings of the Korean Vacuum Society Conference
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• 1995.06a
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• pp.153-153
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• 1995

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.11
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• pp.1913-1918
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• 2016

In order to analyze the power consumption pattern of the DC urban rail system, the method to obtain a solution establishing the current equation according to fixed position of the substation and varying position of the train is used. The proposed analysis method using the network analysis is to model the transfer function of the component constituting a direct current power supply system (dc substation, train, catenary) to the voltage and current. By multiplying the model formula consecutive, it can calculate the voltage and current of each element of power supply circuit and shows a simple case analysis.

• Korean Journal of Heritage: History & Science
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• v.48 no.1
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• pp.132-147
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• 2015

In this article, the research trends regarding the analysis and restoration of the pigments applied on colored cultural properties during past 25 years are reviewed and the future research direction in this field of study is proposed. There are over 100 different pieces of the colored cultural property samples that have been analyzed in Korea during the time and are increasing numbers of studies on comparative investigations as well. In addition, new analysis techniques have been introduced to surpass the limitation of the current analysis techniques and the database construction has been developed tremendously, which will enhance the analysis reliability, indicating fast growth in the related research areas. There are also studies on finding new materials to replace the traditional ingredients for producing color pigments and related other materials to overcome the limitation of the traditional ingredients on top of the steady number of studies on reproduction and restoration of the traditional pigments. These various research efforts will bring much development in this area of research. One suggestion to be made is that there need to be long term planned research works for certain type of studies. For instance, the effect to the colored cultural properties due to the environmental change is one of important research topics that should be carefully studied, which requires longer time period and also more patience than the research works in the current and past trends.