• Health Policy and Management
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• v.30 no.2
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• pp.253-262
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• 2020

Background: The public health care system of a country is shaped and driven by its historical background as well as social, economic, and cultural structures. This study sheds light on the unique features, strengths, and weaknesses of the health insurance systems of South Korea (Korea) and Peru. Methods: The capacity mapping tool was used to explore the Korean and Peruvian population and geographical structures; health insurance laws, regulations, and policies; payment systems; eligibility and contribution collection; and long-term care insurance. Results: The study found that the Korean government took the lead in integrating multiple insurers into a single-payer system in an effort to reinforce and stabilize its health insurance system in 2000. Peru has been developed mixed model such based on taxes and contributions, to address a gap between different social classes. Peruvian government developed a two-axis system, one for low-income earners, financed by taxes, and another financed by contributions paid by workers and government officials in the formal sector. Peru has introduced many variations to its fee payment and insurer systems, target population, and coverage scope, and maintains its health insurance system accordingly to this day. Conclusion: The current study provides observation of the Health Insurance System in two different countries and helps to understand possible ways to improve the health insurance system in both countries. Based on this study, Peru will be able to see how its system differs from Korea's and benefit from the related policy implications.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.447-463
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• 1997

The purpose of this study was to evaluate the effectiveness of copal varnish and five bonding agents(Scotchbond Multi-Purpose Plus Dental Adhesive System, Panavia 21, All Bond 2, Superbond D-Liner II plus, Fuji Duet) in reducing microleakage under amalgam restorations. Class V cavity were prepared on both buccal and lingual surface of sixty extracted human molars with cementum margin and were filled with different kinds of liners and amalgam. All teeth were stored at $37^{\circ}C$ in physiologic saline solution. After 1 week they were thermally stressed for 500 cycles between 5 and $55^{\circ}C$ in baths containing 0.5 % basic fuchsin dye. The dye penetrations were observed with a stereomicroscope. Scanning electron micrographs were taken of representative tooth sections from each group to assess the nature of the tooth/liner/amalgam interface. The statistical test were applied to the results using a one way analysis variance (ANOVA) and Duncan's multiple range test. The results were as follows ; 1. In all groups, the enamel margin showed significantly lower leakage value than the cementum margin (p<0.05). 2. At the dentin and enamel margins, the leakage value of Copalite-lined group showed significantly higher than that of no liner group (p<0.05), but showed significantly lower than that of bonding agent lined-groups (p<0.05). 3. There was no significant difference between the bonding agent lined-groups (p>0.05). 4. On the backscattered scanning electron microscopy observation, discontinuous gaps were observed between amalgam and dentin in the bonding agent-lined amalgam restorations and the bonding agents appeared to fill the gap space and were mixed with amalgam particles. At the amalgam/tooth interface, unsealed dentin and continuous gaps were found in both unlined and Copalite-lined restorations.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.7
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• pp.298-304
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• 2002

Transmuted impurity atoms formed in neutron-irradiated ZnO thin films were theoretically identified first and then experimentally confirmed by photoluminescence (PL). ZnO thin films grown by plasma-assisted molecular beam epitaxy were irradiated by neutron beam at room temperature. The ZnO films consist of eight constituent (Zn and O) isotropes, of which four are transmutable by neutron-irradiation; $^{64}$ , $^{68}$ Zn, $^{70}$ Zn and $^{18}$ O were expected to transmute into $^{65}$ Cu, $^{69}$ Ga, $^{71}$ Ga, and $^{19}$ F, respectively. The concentrations of these transmuted atoms were estimated in this study by considering natural abundance, neutron fluence and neutron cross section. The neutron-irradiated ZnO thin films were characterized by PL. In the PL spectra of the ZnO thin films, the Cu-related PL peaks were seen, but the Ga- or F-associated PL peaks were absent. This observation confirmed the existence of $^{65}$ Cu in the ZnO, but it could not do the formation of the other two. In this paper, the emission mechanism of Cu impurities is described and the reason for the absence of the Ga- or F-associated PL peaks is discussed as well.

• Smart Structures and Systems
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• v.6 no.3
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• pp.225-238
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• 2010

We report on the development of a new technology for the fabrication of Micro-Electro-Mechanical-System (MEMS) strain sensors to realize a novel type of crackmeter for health monitoring of ageing civil infrastructures. The fabrication of micromachined silicon MEMS sensors based on a Silicon On Insulator (SOI) technology, designed according to a Double Ended Tuning Fork (DETF) geometry is presented, using a novel process which includes a gap narrowing procedure suitable to fabricate sensors with low motional resistance. In order to employ these sensors for crack monitoring, techniques suited for bonding the MEMS sensors on a steel surface ensuring good strain transfer from steel to silicon and a packaging technique for the bonded sensors are proposed, conceived for realizing a low-power crackmeter for ageing infrastructure monitoring. Moreover, the design of a possible crackmeter geometry suited for detection of crack contraction and expansion with a resolution of $10{\mu}m$ and very low power consumption requirements (potentially suitable for wireless operation) is presented. In these sensors, the small crackmeter range for the first field use is related to long-term observation on existing cracks in underground tunnel test sections.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.739-750
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• 1997

Treatment of root perforation elicits special considerations due to its blood-contaminated circumstances. It is known that conventional dental restorative materials are all leaking. Calcium sulfate is the material which react with water to become chemically set. This study, therefore, was performed to develop a new compound containing calcium sulfate and to evaluate its physical and biological characteristics. Three materials were used, IRM, calcium sulfate, calcium sulfate-hydroxyapatite compound. The composition of the calcium sulfate-hydroxyapatite compound was basically 50 % of calcium sulfate and 50 % of hydroxyapatite mixed with guajacol. The materials were mixed in conventional way and underwent four physical test procedures, setting time, solubility test, compressive strength, and marginal leakage test. All materials were evaluated under the scanning electron microscope to examine the marginal sealing ability. Animal experiment was also performed to test the materials' tissue response. Twenty-four dog's premolars were tested with either furcation perforations or apical retro-fillings. From the results, we found that calcium sulfate possess the good marginal sealing ability. However, calcium sulfate creates many voids which is caused by crystal thrusting action when it reacts with water. It seemed that the voids caused disintegration of the material which eventually lead to tissue reaction. By compounding calcium sulfate and hydroxyapatite, we were able to obtain the better physical properties but it showed larger marginal gap between the material and the root surface. Within the six weeks observation period, both IRM and calcium sulfate-hydroxyapatite compound showed good tissue responses in animal experiment. It is concluded that calcium sulfate would be the material of choice in root perforation repair, but the physical property needs to be further improved.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1738-1742
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• 2009

Nanocrystalline Zn$Fe_2O_4$ oxide-semiconductor with spinel structure was synthesized by the polymerized complex (PC) method and investigated for its photocatalytic and photoelectric properties. The observation of a highly pure phase and a lower crystallization temperature in Zn$Fe_2O_4$ made by PC method is in total contrast to that was observed in Zn$Fe_2O_4$ prepared by the conventional solid-state reaction (SSR) method. The band gap of the nanocrystalline Zn$Fe_2O_4$ determined by UV-DRS was 1.90 eV (653 nm). The photocatalytic activity of Zn$Fe_2O_4$ prepared by PC method as investigated by the photo-decomposition of isopropyl alcohol (IPA) under visible light (${\geq}$ 420 nm) was much higher than that of the Zn$Fe_2O_4$ prepared by SSR as well as Ti$O_{2-x}N_x$. High photocatalytic activity of Zn$Fe_2O_4$ prepared by PC method was mainly due to its surface area, crystallinity and the dispersity of platinum metal over Zn$Fe_2O_4$.

• Tribology and Lubricants
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• v.30 no.6
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• pp.337-342
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• 2014

The reduction of drag torque is an important research issue in terms of improving transmission efficiency. Drag torque in a wet clutch occurs because of the viscous drag generated by the transmission fluid in a narrow gap (clearance) between the friction plate and a separate plate. The objective of this paper is to observe the effects of the friction plate area and the clearance on the drag torque using finite element simulation. The two-phase flow of air and oil fluid is considered and modeled for the simulation. The simulation analysis reveals that as the rotational speed increases, the drag torque generally increases to a critical point and then decreases sharply at a high speed regime. The clearance between the two plates plays an important role in controlling drag torque peak. An increase in the clearance causes a decrease in shear stress; thus, the drag torque also decreases according to Newton's law of viscosity. An observation of the effect of the area of contact between transmission fluid and friction plate shows that the drag torque increases with the contact area. The flow vectors inside the flow channel present clear evidence that the velocity of the fluid flows is faster with a larger friction plate, that is, in the case of a larger contact area. Therefore, the optimum size of the friction plate should be determined carefully, considering both the clutch performance and drag reduction. It is expected that the results from this study can be very useful as a database for clutch design and to predict the drag torque for the initial design with respect to various clutch parameters.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.16-16
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• 2019

기후변화 시나리오 및 계절예측 자료를 포함한 기후정보를 수자원 분야에 활용하기 위해서는 기후정보의 시 공간적인 상세화(donwscaling)을 필요로 한다. 상세화의 경우 역학적 상세화와 통계학적 상세화로 구분될 수 있으며, 통계학적 상세화를 위해서는 대상 지역의 기후특성을 대표할 수 있는 장기 관측 자료의 확보가 중요하다. 국내의 경우에는 자동기상관측장비(Automatic Weather System, AWS)와 종관기상관측장비(Automatic Synoptic Observation System, ASOS)로 부터 수집된 기상관측자료를 사용할 수 있으나 기후변화 시나리오의 통계적 상세화를 위해서는 30년 이상의 자료 기간을 포함하는 ASOS 자료가 적합하다. 하지만 개발도상국과 같이 기상관측기반이 열악한 지역에서는 잦은 결측 등으로 인하여 품질이 좋은 관측자료의 획득이 어려운 상황이다. 따라서 본 연구에서는 측이 포함된 장기 기상관측 자료로부터 대상 지역의 기후특성을 재현할 수 있도록 기본적인 QC(Quality Control)을 거쳐 결측 자료를 보완할 수 있는 기법 및 R 기반패키지를 개발하여 적용성을 평가하였다. 개발된 기법의 적용성 평가를 위해서 기상청에서 QC를 통해 제공하고 있는 60개 ASOS 지점의 관측자료 중 강수량과 기온 변수를 사용하였다. 최대 50%까지의 현실적인 결측 패턴을 임의로 생성하기 위해 실제 개발도상국 관측자료의 일단위 결측 패턴을 이용하였다. 자료의 QC는 관측일 누락/중복 및 문자형 관측값 등 기본적인 오류 검사, 기온의 경우 물리적 허용 범위에 대한 검사, 최고기온과 최저기온의 비교 및 계측기 오작동에 의한 동일한 값의 반복 등을 포함한 내적 일치성 검사를 우선적으로 수행한다. 이후 결측값에 대해서 인근 기상관측소와의 상관성 분석 결과를 기반으로 결측값을 채우고, 최종적으로는 다양한 위성자료 및 재분석 자료 중에서 일단위 기후특성의 재현성 평가를 통해 선정된 격자형 자료와의 상관성 분석 결과를 기반으로 결측값을 보정하였다. 기온의 경우는 결측률이 높더라도 월평균 기후특성에 큰 영향을 미치지 않았지만 강수의 경우에는 5% 이상의 결측이 발생하는 경우 월평균 강수량에 영향을 미쳐 지역의 강수량을 과소 추정하는 결과를 보였다. 개발된 QC 기법을 강수 자료에 적용한 결과 월평균 기후특성을 잘 복원하는 결과를 보였지만, 일단위 강우 사상의 재현에 있어서는 미흡한 결과를 보였다.

• Journal of Forest and Environmental Science
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• v.37 no.1
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• pp.62-68
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• 2021

Despite numerous efforts on reducing road-kill worldwide, the collisions have been occurring continuously. Many factors are affecting road-kill occurrences and the effect is various by species. We investigated Hydropotes inermis argyropus road-kill characteristics on the national highway. We examined 9,099 H. i. argyropus road-kill points with distance to the gaps on road (interchange and intersection) and distance to six natural land-cover types as explanatory variables. We also examined the number of road-kill occurrences according to temporal variation using chi-square test with 9,658 events. In general, H. i. argyropus road-kill location tended to occur close to the gaps on road, agricultural lands and forests. The average distance from road-kill to the gap was 694.7 m and 78.6% of the collisions were occurred within 1 km from the gaps. In addition, Kruskal-Wallis test showed the distance between road-kill points and each land cover and the gaps was significantly different. The temporal analyses showed that the differences of the H. i. argyropus road-kill frequency are significant in both month and season. Our results implies H. i. argyropus road-kill location tended to occur close to the gaps on road, agricultural lands and forests in general, especially during May and June, according to their seasonal behavior. Thus, we suggest there is a need of concentrated management on the roads with specific characteristics for both wildlife and human safety.

• Journal of Information Technology Applications and Management
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• v.28 no.1
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• pp.53-61
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• 2021

The year 2020 was a time when the coronavirus infections-19 (COVID-19) caused various changes in society. In particular, the fields that have been conducted face-to-face have been greatly confused by the transition to an online non-face-to-face method, and this is the case with the field of education. There are two main advantages of offline education. The first is that we can improve our understanding through communication with teachers, and the second is that we can develop social skills through interaction with friends. But as online classes progressed due to corona 19, interaction could not be achieved. As a result, the motivation for learning has been reduced due to difficulties in real-time feedback, and the participation rate has been significantly lowered, especially in lower grades, raising concerns about the learning gap that will occur after corona 19. However, there are some cases in which online classes were conducted as effectively as offline classes by utilizing various contents. What they have in common is the use of content. Teachers generally improved the quality of education by linking interesting sights and videos that enhance learning comprehension. The provided video conveys learning-related content into stories, enabling intuitive observation. Many students were already enjoying these videos through VOD (Video on Demand) such as TV and YouTube, they were able to connect their easy access to content and interest in learning. Appropriate use of video content has rather increased the learning effect and should continue after corona 19. Therefore, it is necessary to study methodologies that apply video content efficiently to education. This study looked at the steps that needed content application through the development of education programs, and observed its meaning. Students were curious about the content, motivated to learn and participated in learning on their own. Intuitive learning, conducted through appreciation, play and content production, provided an opportunity to learn on their own in everyday life.