• Restorative Dentistry and Endodontics
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• v.25 no.2
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• pp.299-308
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• 2000

The purpose of this in vitro study was to evaluate the microleakage of 5 curing methods in class V composite restorations which are composed of two-step light curing, pulse-delay cure, low curing-light intensity, moderate curing-light intensity and high curing-light intensity. In this study, class V cavities were prepared on buccal and lingual surfaces of 50 extracted human upper or lower molars on cementum margin. Single Bond adhesive and Z-100 shade A2 were applied for each group following the manufacture's instruction. The experimental teeth were randomly divided into 5 groups of 10 samples (20 surfaces) each. Group 1: two-step light curing; Group 2: pulse-delay cure; Group 3: low curing-light intensity; Group 4: moderate curing-light intensity; Group 5: high curing-light intensity. After 500 thermocycling between $5^{\circ}C$ and $55^{\circ}C$, the 60 teeth were placed in 2% methylene blue dye for 24 hours, then rinsed with tab water. The specimens were embedded in clear resin, then sectioned buccolingually through the center of restoration with a low speed diamond saw. The dye penetration on each of the specimen was then observed with a stereomicroscope at ${\times}20$. The composite resin/tooth interfaces were examined under Scanning Electron Microscopy. The results were statistically analyzed using the Kruskal-Wallis One Way ANOVA and Dunn's Method. The results of this study were as follows. 1. In all groups, the leakage values seen at the enamel margin were significantly lower than those seen at the dentin margin(P<0.05). 2. No group in this study showed significant differences in leakage values at both the enamel and the dentin margins(P<0.05). 3. In all groups, the gaps seen at the enamel margin were significantly lower than those seen at the dentin margin(P<0.05). 4. The gaps in this study showed significant differences and two-step light-curing and low curing-light intensity produced significant less gap than high curing-light intensity(P<0.05).

• Korean Journal of Dental Materials
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• v.42 no.2
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• pp.95-106
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• 2015

Hardening mechanism associated with post-firing heat treatment of softening heat treated and then firing simulated Pd-Ag-Au alloy for bonding porcelain was examined by observing the change in hardness, crystal structure and microstructure. By post-firing heat treatment of as-cast, solution treated and pre-firing heat treated specimens at $650^{\circ}C$ after casting, the hardness value increased within 10 minutes. Then, hardness consistently increased until 30 minutes, and gap of hardness value among the specimens was reduced. The increase in hardness after post-firing heat treatment was caused by grain interior precipitation in the matrix. The softening heat treatment did not affect the increase in hardness by post-firing heat treatment. The precipitated phase from the parent Pd-Ag-Au-rich ${\alpha}$ phase with face-centered cubic structure by post-firing heat treatment was $Pd_3$(Sn, In) phase with face-centered tetragonal structure, which has lattice parameters of $a_{200}=4.0907{\AA}$, $c_{002}=3.745{\AA}$. From above results, appropriate post-firing heat treatment in order to support the hardness of Pd-Ag-Au metal substructure was expected to bring positive effects to durability of the prosthesis.

• Journal of Technology Innovation
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• v.28 no.4
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• pp.127-150
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• 2020

The World Health Organization (WHO) declared the third pandemic in history after the Hong Kong flu and swine flu. The outbreak of Corona 19 dramatically reduced exchanges between countries, while rapid contagion created a time gap in economic fluctuations by country. In January 2020, the trade dispute between the US and China entered into a consensus phase, but the economic decoupling phenomenon caused by Corona 19 made it difficult for China to balance trade with the US and made it difficult to comply with the terms of the trade dispute agreement between the US and China. President Trump attributed the responsibility for the spread of Corona 19 to China, and pointed out that the cause of the economic downturn was the infringement of Chinese trade secrets and illegal copies, and protectionism arose. As a result, China protested fiercely, and the conflict with the United States deepened. The US has declared trade sanctions on Huawei and SMIC, which are key companies in China's semiconductor industry, and is predicting the risk of a disconnection of the semiconductor value chain between the US and China. The separation of the value chain of the semiconductor industry has the potential to have a big impact on the semiconductor industry, a structure that is highly specialized and monopolized by certain countries and companies in the value chain. This paper aims to deal with the risk of disconnection in the semiconductor value chain between the US and China reignited by Corona 19, the impact and change of the global semiconductor industry value chain, and the response strategies of Korean semiconductor companies.

• Journal of Korea Trade
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• v.25 no.5
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• pp.39-57
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• 2021

Purpose - This research uses ocean marine insurance (OMI) statistics, international emails, focus-group interviews, and surveys to fill the gap between the theory of behavioral insurance, particularly status quo bias (SQB), and the practice of OMI in Korea. The contractual forms of OMI, the oldest and most globalized form of commercial insurance, were developed in the UK as the Institute Cargo Clauses in 1906 and revised in 1963, 1982, and 2009. SQB has been academically explored, mostly in health insurance and the financial services sector, but never in OMI. Thanks to the availability of OMI statistics in Korea, we can conduct SQB research here for the first time in this field. Design/methodology - We show the existence of SQB in the OMI of Korea through Korean statistics between 2009 and 2018, email correspondence with experts in the UK, Germany, and Japan, focus-group interviews with Korean OMI underwriters, an in-depth interview with one underwriter, and a survey of 15 OMI insureds (company representatives). Findings - We find that Korean foreign traders rely on the old-type OMI contracts developed in 1963, whereas other industrialized countries use the newest type of OMI contract developed in 2009. With a simple loss ratio analysis during 2009-2018, we show that the behavior of insurers has little to do with rational profit maximization and is instead driven by irrational bias, as they forgo the more profitable contracts provided by the new clauses by keeping the old clauses. The consistent addiction to old types of contracts in the OMI market suggests strong SQB among Korean exporters, importers, bankers, or insurers, which we confirmed in our interviews and survey. Originality/value - This research has significant originality and academic value because it reports new findings with crucial implications for the development of efficient trade practices and policy. First, this research is based on actual statistics that have not been used in previous Korean research on OMI. Second, this research shows that all-risk OMI policies provide more value to insureds, in terms of coverage given premium, than partial coverage policies, which differs from arguments previously made in Korea. Third, this research reveals strong SQB in Korea, where foreign trade plays a pivotal role in economic growth. That bias could be attributable to uninformed traders, informed but idle insurers, or conservative bankers. Fourth, to further develop foreign trade, policy initiatives are needed to review the current practices of OMI contracts and move forward with the new contract forms. All of these findings and arguments are both new and important.

• The Journal of the Korea Contents Association
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• v.22 no.10
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• pp.445-459
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• 2022

This study presented a plan to improve the life satisfaction and leisure status of the elderly in the With COVID-19 era, and the life satisfaction of the elderly. For this purpose, we investigated life satisfaction and leisure life for 107 senior citizens at the Gyeonggi Senior Welfare Center, and the following results were obtained. First, it can be seen that overall life satisfaction was relatively lower after Corona than before. Second, in the correlation between leisure activity and life satisfaction, there was no significant correlation between the level of leisure activity and life satisfaction before Corona, and a significant positive correlation was found between the level of leisure activity and life satisfaction after Corona. seemed If alternative measures are proposed according to these results, first, it is necessary to seek ways to improve and manage the environment for the elderly in the with Corona era in the local community. In particular, in order to reduce the adaptation gap among the elderly due to the many changes in digital technology, institutions related to the elderly are providing education on how to use smartphones and kiosks, but it needs to be expanded as a community-wide measure. Second, a systematic system for health care for the elderly in the era of With Corona must be provided. Third, the old-age income security system and support are required so that the minimum living security is guaranteed for the elderly who are experiencing economic difficulties due to the corona virus. Fourth, it is necessary to revitalize programs related to talking to the elderly and counseling for the improvement of relationships and location satisfaction due to social distance and relationship atrophy due to Corona.

• Journal of Appropriate Technology
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• v.7 no.1
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• pp.93-101
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• 2021

Scientists and engineers without borders (SEWB) was established on 2009 as the NGO having specialist groups to support the underprivileged in developing countries living in the isolated area and having water and sanitation problems. After the SDGs were suggested by the UN on 2016, activities are globally conducted by the nation, NGO and etc. to improve health and education of the underprivileged in developing countries. SEWB also have been conducted the projects in Korea and developing countries to reduce the gap of the infrastructure between the developed and developing countries and to help sustainable development in the developing countries by providing appropriate technology. In Korea, SEWB have been held international conference on appropriate technology (ICAT), lectures, and competitions for specialists and students. In developing countries including Cambodia and other 5 countries, SEWB have been provided water packages funded by iCOOP KOREA and volunteer opportunities. Since 2019, 'SEWB sustainable village development project' have been conducted in Bot Veng village, Cambodia to improve infrastructures on water, electricity, transportation, and agriculture by using desalination system, Solar Cow system, strengthened wooden bridge, and poultry farm, respectively. The developed solution for developing countries from SEWB could contribute to eliminate the water shortage and poverty.

• The Journal of Korean Academy of Sensory Integration
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• v.21 no.3
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• pp.79-102
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• 2023

Objective : Autistic Spectrum Disorders(ASD) is a developmental disorder characterized by atypical sensory adaptation, communication problem, stereotyped behavior, and feeding disorders. The reasons for ASD feeding disorders are oral sensory motor, cognitive, behavioral, and social problems. Major symptoms include picky eating, selective eating, food refusal, food neophobia, limited food variety, and food aversion. ASD feeding disorders could be accompanied by various problems such as health and nutrition intake problems, feeding development, eating-related sociability, and family and caregiver stress. Feeding problems and disorders in ASD can present from birth. However, ASD is diagnosed by the age of 3, and there might be an appropriate treatment gap. Usually, symptoms of feeding disorders tend to decrease with age. However, the symptoms often remain, so early evaluation, intervention, and periodic checking are necessary. In this study, the general information about the feeding disorder characteristics of ASD, influencing factors, and intervention were described through a literature review. Conclusion : Sensory-based therapy and behavior-based therapies are generally used for feeding disorders in ASD. Sensory-based therapy is effective for food sensitivity and behavior-based therapy for food selection. As the symptoms of feeding disorders in ASD are diverse, a comprehensive approach includes play and participation, oral motor exercise, diet, and daily life. However, appropriate evaluation, intervention protocol, and guidelines for the treatment of feeding disorders in ASD are limited. Therefore, a complex approach based on a more systematic understanding is needed. Feeding rehabilitation specialists, such as occupational therapists, should provide appropriate evaluation and intervention.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.625-636
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• 2017

Dyslipidemia, hypertension, and diabetes are well-established risk factors for cardio-cerebrovascular disease (CVD). Although the prevalence of dyslipidemia among Korean adults is very high, its management is known to be poor. The aim of this study was to assess the prevalence, awareness, treatment, and control rates of dyslipidemia among adults aged 30 years and older in Gangwon-do, Korea. Analysis included 58,121 adults (29,123 males and 28,998 females) participating in the 2013-2014 Korea National Health Screening Program (KNHSP). Dyslipidemia was defined according to the treatment criteria rather than the diagnostic criteria in Korea. Therefore, high-low-density lipoprotein cholesterol (LDL)-cholesterolemia was deemed present in individuals with LDL-cholesterol levels that exceeded the appropriate risk-based threshold. The age-standardized prevalence was highest in dyslipidemia (32.5%), followed by hypertension (25.1%), and diabetes (9.4%). The awareness rate was 76.7% for hypertension and 74.7% for diabetes, but only 10.6% for dyslipidemia. The lowest patient treatment was found for dyslipidemia (9.4%). The control rate among those undergoing treatment was highest for hypertension (75.8), followed by dyslipidemia (63.3%), and diabetes (43.9%). The higher CVD-risk categories showed lower control rates of hyper-LDL-cholesterolemia. The prevalence of dyslipidemia was higher than hypertension and diabetes, but awareness and treatment rates were lower. Our findings indicate there is a wide gap between the prevalence of dyslipidemia and subsequent treatment, which suggests that effective strategies are required to improve dyslipidemia management. It would be worthwhile to strengthen the follow-up management of patients with dyslipidemia in the KNHSP, especially for the high risk group of CVD.

• Journal of Korean Home Economics Education Association
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• v.32 no.3
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• pp.161-177
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• 2020

This research aims to identify the relevance of 'Adolescence consumption' units to ESD(Education for Sustainable Development), and to analyze the unit's inquiry tendency through the Romey analysis method. The assessment criteria in association with ESD developed in the previous literature were summarized and established to set up an analysis framework consisted of 11 key points including environmental perspective (natural resources, climate change/disaster prevention and mitigation, and sustainable rural and urban systems), economic perspective (corporate sustainability, market economy, and poverty gap mitigation), and socio-cultural perspective (human rights/peace/human protection, cultural diversity and understanding, health/safety, civic engagement, and management of nation). With this framework, the learning contents of 'adolescence consumption life' unit in twelve middle school Home Economics textbooks were analyzed including the texts, images/illustrations/tables/graphs, and activities. The analysis revealed that the core elements of the 'market economy' and 'management of nation' from the economic perspective were presented in three different formats: texts, images/illustrations/tables/graphs, and activities. However, relatively insufficient contents were presented in terms of health/safety, civic engagement, sustainable rural and urban systems, and corporate sustainability, and thus, development of textbooks dealing with various ESD contents is neededrecommended. Additionally, most textbooks' texts and images/illustrations/tables/graphs tend to be authoritative, while activities and assignments exhibited an inquiry tendency. It is advisable to incorporate a wider variety of ESD-related content in Home Economics classes and creatively employ inquiry-based learning activities for the development of pro-sustainable-development consumption values and behavioral tendencies among young students.

• Journal of dental hygiene science
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• v.1 no.1
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• pp.46-52
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• 2001

The purpose of this study was to examine dental personnels' concern for health, their personal protection manner, and whether or not they were inoculated against hepatitis B and made an inquiry of patients about that. It's ultimately meant to serve as a basis for the preparation of an anti-infection guide for the protection of dental personnels against all sorts of infectious diseases. After a survey was conducted from March 29 through May 9, 2001, the following findings were obtained: (1) The dental personnel group that had worked for 5 to less than 7 years took health examination the most, with 71.4%, before joining the hospital, and 61.5% of those who had served for 9 years or more, the greatest percentage, took medical checkup after joining the hospital(P<0.05). (2) The largest percentage of being inoculated against the anti-B type hepatitis after employment was 71.4% of the dental personnels over 35, and 57.7% of those with 9-year or more working experiences. Therefore, their age and service term made a significant difference(P<0.05). (3) There was no significant gap in personal protection practices between the dental hygienists and nurse aids(P>0.05). But the use of safety goggles for treatment was not properly done, with just 1.48 on the basis of 3 points, whereas the use of mask was scored 2.40 and the use of gloves was scored 1.96. (4) After a narcotic was used once, the leftovers were wasted by 89.7% of the dental hygienists and 70.0% of the nurse aids. More dental hygienists wasted them(P<0.05). (5) For hand washing, antibiotic liquid soap was used by 19.3% of the dental hygienists and 10.0% of the nurse aids, which were both very low percentage. And just 37.2% of the dental hygienists utilized a disposable paper towel to dry their hands, and only 36.0% of the nurse aids used the same(P<0.05).