• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.95-99
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• 2018

High thermal conductivity films with electrically insulating properties have a great potential for the effective heat transfer as substrate and thermal interface materials in high density and high power electronic packages. There have been lots of studies to achieve high thermal conductivity composites using high thermal conductivity fillers such alumina, aluminum nitride, boron nitride, CNT and graphene, recently. Among them, hexagonal-boron nitride (h-BN) nano-sheet is a promising candidate for high thermal conductivity with electrically insulating filler material. This work presents an enhanced heat transfer properties of ceramic/polymer composite films using h-BN nano-sheets and PVA polymer resins. The h-BN nano-sheets were prepared by a mechanical exfoliation of h-BN flakes using organic media and subsequent ultrasonic treatment. High thermal conductivities over $2.8W/m{\cdot}K$ for transverse and $10W/m{\cdot}K$ for in-plane direction of the cast films were achieved for casted h-BN/PVA composite films. Further improvement of thermal conductivity up to $13.5W/m{\cdot}K$ at in-plane mode was achieved by applying uniaxial compression at the temperature above glass transition of PVA to enhance the alignment of the h-BN nano-sheets.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.36.2-36.2
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• 2018

Cosmic reionization era in the early universe was playing a leading part on making the present universe we know. However, we have not been able to reveal the main contributor to the cosmic reionization to date. Faint quasars have been mentioned as the alternative due to the uncertainty of the faint end slope of the quasars luminosity function. With the availability of the deep (~25mag) images from Subaru Hyper Suprime-Cam (HSC) Strategic Program survey, we have tried to find more quasar with low luminosity in the ELAIS-N1 field. Faint quasar candidates were selected from several multi-band color cut criteria based on the track of the simulated quasar at z ~ 5. The Infrared Medium-deep Survey (IMS) and The UKIRT Infrared Deep Sky Survey (UKIDSS) - Deep Extragalactic Survey (DXS) provide J band information which is used to cover the relatively long wavelength range of quasar spectra. To search the reliable candidates with possible Lyman break, medium-band observation was performed by the SED camera for QUasars in EArly uNiverse(SQUEAN) in the McDonald observatory and Seoul National University 4k Camera(SNUCAM) in the Maidanak observatory. Photometric redshifts of the observed candidates were estimated from chi-square minimization. Also, we predicted the importance of the faint quasar to the cosmic reionization from the expected number density of the faint quasar.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.4
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• pp.87-96
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• 2021

Determining design rainfall is the first step to plan an agricultural drainage facility. The objective of this study is to evaluate whether the current method for parameter estimation is reasonable for computing the design rainfall. The current Gumbel-Kendall (G-K) method was compared with two other methods which are Gumbel-Chow (G-C) method and Probability weighted moment (PWM). Hourly rainfall data were acquired from the 60 ASOS (Automated Synoptic Observing System) stations across the nation. For the goodness-of-fit test, this study used chi-squared (𝛘²) and Kolmogorov-Smirnov (K-S) test. When using G-K method, 𝛘² statistics of 18 stations exceeded the critical value (𝑥²_a=0.05,df=4=9.4877) and 10, 3 stations for G-C method, PWM method respectively. For K-S test, none of the stations exceeded the critical value (D^a=0.05_n=0.19838). However, G-K method showed the worst performances in both tests compared to other methods. Subsequently, this study computed design rainfall of 48-hour duration in 60 ASOS stations. G-K method showed 5.6 and 6.4% higher average design rainfall and 15.2 and 24.6% higher variance compared to G-C and PWM methods. In short, G-K showed the worst performance in goodness-of-fit tests and showed higher design rainfall with the least robustness. Likewise, considering the basic assumptions of the design rainfall estimation, G-K is not an appropriate method for the practical use. This study can be referenced and helpful when revising the agricultural drainage standards.

• Membrane Journal
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• v.31 no.6
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• pp.371-383
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• 2021

Anion exchange membranes have been used for water electrolysis, which can produce hydrogen, and fuel cells, which can generate electrical energy using hydrogen fuel. Anion exchange membranes operate based on hydroxide ion (OH^-) conduction under alkaline conditions. However, since the anion exchange membrane shows relatively low ion conductivity and alkaline stability, there is still a limit to its commercialization in water electrolysis and fuel cells. To address these issues, it is important to develop novel anion exchange membrane materials by rationally designing a polymer structure. In particular, the polymer structure and synthetic method need to be controlled. By doing so, for polymers, the physical properties, ionic conductivity, and alkaline stability can be maintained. Among many anion exchange membranes, poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) is commercially available and easily accessible. In addition, the PPO has relatively high mechanical and chemical stability compared to other polymers. In this review, we introduce the recent development strategy and characteristics of PPO-based polymer materials used in anion exchange membranes.

• Quality Improvement in Health Care
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• v.27 no.2
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• pp.73-82
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• 2021

Purpose: This study aims to examine the quality of tuberculosis (TB) care after the 1st to 3rd national quality assessment (QA) program for TB healthcare service in Korea was conducted. Methods: We analyzed Health Insurance Review & Assessment Service (HIRA) claims data of new TB patients during the period of January to June from 2018-2020. The new TB patients were defined as TB patients reported to Korea Centers for Disease Control and Prevention Agency (KCDA). The unit of analysis was the patient. Chi-square tests were used to analyze the differences in indicator value according to the types of medical facilities. The QA indicators of TB care were divided into 3 areas consisting of the following 7 quality indicators: 4 indicators of diagnosis test (the rate of acid-fast bacilli smear, the rate of acid-fast bacilli culture, the rate of Mycobacterium tuberculosis-polymerase chain reaction, drug susceptibility test), 1 compliance of treatment guideline, and 2 indicators of care management of TB patients (encounter rate, day of therapy). Results: The QA program for TB care was conducted among 8,246 patients from 534 facilities in 2020. The value of the 7 quality indicators was shown to increase as a result of the QA program. The indicators of the diagnostic test were all higher than 95%, with the exception of the drug susceptibility test which was 84.8%. Both indicators for care management of TB patients were 88.5%. Conclusion: The quality of TB care has been improving with the implementation of the QA program. In order to continue to improve the quality of TB care, it will be necessary to disclose the results of the QA program in medical facilities in the future.

• Journal of Marine Life Science
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• v.4 no.1
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• pp.38-43
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• 2019

The deformity occurring at the early developmental stage of red spotted grouper (Epinephelus akaara) causes detrimental effects on the process of juvenile production. In this study, we have compared the expressions of several key genes (insulin like growth factor 1: IGF-1, bone morphogenic protein 4: BMP4, peroxisome proliferator-activated receptors γ: PPARγ, matrix Gla protein: MGP) for morphogenesis between normal and 2 types (cephalic and jaw) of deformed juvenile fish. Expression of these genes were investigated in the brain, liver and muscle of each group of fish (n=20) by real-time PCR. Expression of IGF-1 and BMP4 mRNA in the brain and liver showed significant difference between normal and deformed fish (p<0.05). However, no difference was observed in the expression of PPARγ and MGP mRNA between normal and deformed fish in any tissues. It seems certain that IGF-1 and BMP4 are associated with the state of deformity in juvenile red spotted grouper.

• 지역과문화
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• v.7 no.3
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• pp.49-79
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• 2020

This study focuses on the analyzing historical and cultural resources formed during the Goryeo, Chosun, and Anti-Japanese Movement periods after the Silla period with the aim of finding ways to utilize its cultural contents. The viewpoint of analysis was made from the perspective of exchange, naturalization, and faith, and the following conclusions were obtained from the analysis. First of all, from the exchange perspective, the activities of Choi Chi-won, Seogyu, and Song Young-gu contributed to the formation of regional historical and cultural contents, such as leaving a lot of ruins or geographic stories in the area and a heritage of good human exchange. From the point of view of naturalization, Du Kyung-ryeong, Cheon Man-ri, and Jeong Yul-seong contributed to the history and culture of the story and the formation of heritage by doing such as contributing activities to the war, anti-Japanese movement for the nation, and the formation of the nation. The most representative from a religious point of view is the Guan Yu faith, which has become a faith believed by the authorities and civilian as a brave longevity and a symbol of the victory of war. The related symbols, paintings, etc. also are objects of worship and have become valuable local Chinese cultural resources as artistic values. Therefore, from a cultural point of view, there is a need to further develop and utilize these China-related historical and cultural resources as good cultural contents by elaborating their stories and local festivals, book culture branding, international music festivals, and exploring various cultures such as Chinese tour courses.

• Journal of Dental Anesthesia and Pain Medicine
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• v.23 no.2
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• pp.101-110
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• 2023

Background: Dentists make various efforts to reduce patients' anxiety and fear associated with dental treatment. Dental sedation is an advanced method that dentists can perform to reduce patients' anxiety and fear and provide effective dental treatment. However, dental sedation is different from general dental treatment and requires separate learning, and if done incorrectly, can lead to serious complications. Therefore, sedation is performed by a limited number of dentists who have received specific training. This study aimed to investigate the proportion of dentists who practice sedation and the main sedatives they use in the context of the Republic of Korea. Methods: We used the customized health information data provided by the Korean National Health Insurance. We investigated the number of dental hospitals or clinics that claimed insurance for eight main sedatives commonly used in dental sedation from January, 2007 to September, 2019 at the Health Insurance Review and Assessment Service. We also identified the changes in the number of dental medical institutions by region and year and analyzed the number and proportion of dental medical institutions prescribing each sedative. Results: In 2007, 302 dental hospitals prescribed sedatives, and the number increased to 613 in 2019. In 2007, approximately 2.18% of the total 13,796 dental institutions prescribed sedatives, increasing to 3.31% in 2019. In 2007, 168 institutions (55.6%) prescribed N₂O alone, and in 2019, 510 institutions (83.1%) made claims for it. In 2007, 76 (25.1%) hospitals made claims for chloral hydrate, but the number gradually decreased, with only 29 hospitals (4.7%) prescribing it in 2019. Hospitals that prescribed a combination of N₂O, chloral hydrate, and hydroxyzine increased from 27 (8.9%) in 2007 to 51 (9%) in 2017 but decreased to 38 (6.1%) in 2019. The use of a combination of N₂O and midazolam increased from 20 hospitals (6.6%) in 2007 to 51 hospitals (8.3%) in 2019. Conclusion: While there is a critical limitation to the investigation of dental hospitals performing sedation using insurance claims data, namely exclusion of dental clinics providing non-insured treatments, we found that in 2019, approximately 3.31% of the dental clinics were practicing sedation and that N₂O was the most commonly prescribed sedative.

• 한국노년학
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• v.29 no.4
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• pp.1463-1478
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• 2009

The purpose of this study is to investigate the characteristics of the elderly based on the types of Kyungrodang participation and explores ways toward development of Kyungrodang. A national sample data, collected by the Korean Institute for the Health and Social Welfare in 2004 is analyzed by employing Chi-Square test of independence, ANOVA, and multiple logistic regression(n=3,005). A significant difference is noted in age, area, and socioeconomic status among the elderly based on the types of Kyungrodang participation. The results show that those elderly living in rural areas with older and lower socioeconomic status are more likely to participate at Kyungrodang, whereas, elderly living in urban areas with younger and higher socioeconomic status are less likely to participate at Kyungrodang and discontinue to use the services. Although there is a difference between the gender, the most significant reason for not using and discontinuing Kyungrodang is because the elderly can not get along with the other participants. In other words, the major problem that needs to be solved is to socializing and providing service programs satisfying all participants. Based on the results and recent socioeconomic changes of the older population, some policy issues are suggested for the development of Kyungrodang.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.3
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• pp.286-294
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• 2008

In order to understand the physical properties of deep-sea sediments, which mainly consist of pelagic red clays, sediment samples were collected at 24 stations using a multiple corer in the Clarion-Clipperton fracture zone of the northeast equatorial Pacific. The sampled sediment cores were examined for the mass physical properties(i.e. grain size distribution, mean grain size, water content, specific grain density, wet bulk density, void ratio, and porosity) and the geotechnical properties(i.e. shear strength and consistency limits) with the content of biogenic opal and mineral composition. Although KR1 and KR2 areas on the same latitude are logitudinally far from each other, the mass physical properties of these areas are not distinctly different except for shear strengths. The maximum shear strength of surface sediments in KR2 area is higher than that in KR1 due to the appearance of a consolidated lower layer(Unit 3) in the sediment core from KR2.