• 한국융합학회논문지
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• 제8권10호
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• pp.305-310
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• 2017

본 연구는 노인의 주관적 건강, 근로능력, 경제활동 참여, 삶의 만족 간 구조적 관계를 분석하는 데 목적이 있다. 최근 각 사회에서는 생산적 노화, 적극적 노년 등의 관점을 통해 노인에 대한 사회적 부담을 경감시키고 부정적 인식을 완화시키기 위해 노력해 왔으며, 특히 삶의 질을 향상시키기 위한 건강과 참여에 주목하고 있다. 본 연구의 분석 대상은 한국복지패널 10차 데이터(2015년)에서 65세 이상인 노인 3,392명을 대상으로 하였다. 분석 결과, 노인의 건강과 근로능력, 경제활동 참여는 삶의 만족에 직접적인 영향을 미치는 것으로 나타났다. 둘째, 노인의 건강은 근로능력과 경제활동 참여에 유의한 영향을 미쳤다. 셋째, 근로능력은 경제활동 참여에 정적으로 유의한 영향을 미쳤다. 분석결과를 바탕으로, 노인의 삶의 만족을 향상시키기 위한 주요 요인으로써 건강과 근로 관련 요인들에 대해 중요하게 고려할 것을 제언하였다.

• The Journal of Advanced Prosthodontics
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• 제12권4호
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• pp.218-224
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• 2020

PURPOSE. The objectives of this study were to evaluate the fracture strength and fracture patterns of provisional crowns fabricated from different materials and techniques after receiving stress from a simulated oral condition. MATERIALS AND METHODS. A monomethacrylate-based resin (Unifast Trad) and a bis-acryl-based (Protemp 4) resin were used to fabricate provisional crowns using conventional direct technique. A milled monomethacrylate resin (Brylic Solid) and a 3D-printed bis-acrylate resin (Freeprint Temp) were chosen to fabricate provisional crowns using the CAD/CAM process. All cemented provisional crowns (n=10/group) were subjected to thermal cycling (5,000 cycles at 5°-55℃) and cyclic occlusal load (100 N at 4 Hz for 100,000 cycles). Maximum force at fracture was tested using a universal testing machine. RESULTS. Maximum force at fracture (mean ± SD, N) of each group was 657.87 ± 82.84 for Unifast Trad, 1125.94 ± 168.07 for Protemp4, 953.60 ± 58.88 for Brylic Solid, and 1004.19 ± 122.18 for Freeprint Temp. One-way ANOVA with Tamhane post hoc test showed that the fracture strength of Unifast Trad was statistically significantly lower than others (P<.01). No statistically significant difference was noted among other groups. For failure pattern analysis, Unifast Trad and Brylic Solid showed less damage than Protemp 4 and Freeprint Temp groups. CONCLUSION. Provisional crowns fabricated using the CAD/CAM process and the conventionally fabricated bis-acryl resins exhibited significant higher fracture strength compared to conventionally fabricated monomethacrylate resins after the aging regimen. Therefore, CAD/CAM milling and 3D printing of provisional restorations may be good alternatives for long term provisionalization.

• Steel and Composite Structures
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• 제22권3호
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• pp.537-565
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• 2016

Australian railway networks possess a large amount of aging timber components and need to replace them in excess of 280 thousands $m^3$ per year. The relatively high turnover of timber sleepers (crossties in a plain track), bearers (skeleton ties in a turnout), and transoms (bridge cross beams) is responsible for producing greenhouse gas emissions 6 times greater than an equivalent reinforced concrete counterparts. This paper presents an innovative solution for the replacement of aging timber transoms installed on existing railway bridges along with the incorporation of a continuous walkway platform, which is proven to provide environmental, safety and financial benefits. Recent developments for alternative composite materials to replace timber components in railway infrastructure construction and maintenance demonstrate some compatibility issues with track stiffness as well as structural and geometrical track systems. Structural concrete are generally used for new railway bridges where the comparatively thicker and heavier fixed slab track systems can be accommodated. This study firstly demonstrates a novel and resilient alterative by incorporating steel-concrete composite slab theory and combines the capabilities of being precast and modulated, in order to reduce the depth, weight and required installation time relative to conventional concrete direct-fixation track slab systems. Clear benefits of the new steel-concrete composites are the maintainability and constructability, especially for existing railway bridges (or brown fields). Critical considerations in the design and finite element modelling for performance benchmarking of composite structures and their failure modes are highlighted in this paper, altogether with risks, compatibilities and compliances.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권2호
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• pp.1-7
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• 2016

Ferrous slag is a by-product from steel making process and waste concrete is generated from construction activities. Large part of ferrous slag and waste concrete are recycled as construction materials. However, Ca²⁺ leaching out of ferrous slag and waste concrete in the water-contacting environment can cause a strength change. Strength can be reduced due to the dissolution of solid form of CaO which is one of the main contents of ferrous slag and waste concrete. On the other hand, strength can be enhanced due to the pozzolanic reaction of cementitious components with water. In this study, steelmaking slag, blast furnace slag, and waste concrete were aged by exposure to raining events, and the change of their compaction and shear strength characteristics was investigated. Optimum moisture content of all materials used in this study increased with aging period while maximum dry unit weight slightly decreased, implying that the relative contents of fine particles increased as the CaO solid particles were dissolved. Internal friction angle and shear strength of recycled materials also increased with aging period, indicating that the materials became denser by the decrease of void ratio attributed to the fine particles generated during the weathering process and the development of cementitious compounds increasing the bonding and interlocking forces between the particles. The results of this study demonstrated that mechanical strength of recycled materials used as construction materials has little chance to be deteriorated during their service life.

• 사물인터넷융복합논문지
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• 제8권5호
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• pp.11-16
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• 2022

상수도분야 인공지능 기술개발 관심도가 증가함에 따라 상수도 관로에 대해서 노후관 상태평가 데이터 결과를 활용하여 반복적인 학습으로 개량 의사결정 등급을 예측할 수 있는 인공신경망 알고리즘을 개발하고 검증과정을 통하여 가장 신뢰성 있는 예측 모델을 제시하고자 한다. 2020년 한강유역의 노후관로 정비 기본계획에 의한 간접평가 데이터 12개 항목을 기반으로 데이터 전처리 하고 인공신경망 알고리즘을 적용하여 반복학습과 검증을 통해 계산된 결과값과 직접평가 결과값의 일치율이 90% 이상이 되도록 역전파 과정을 통해 가중치를 업데이트 하면서 최적화하여 관로 등급을 예측하는 알고리즘을 개발하였다. 알고리즘 정확도 검증결과 모든 관종 데이터가 고르게 분포되어 있고 학습 데이터가 많아야 예측평가 정확도가 높아지는 것을 확인할 수 있었다. 향후 전국의 다양한 데이터가 확보되면 인공신경망을 이용한 관로등급 예측의 신뢰도가 좀 더 향상되어 객관화된 노후관 상태평가 의사결정 지원 역할을 수행할 수 있을 것으로 기대된다.

• 한국재료학회지
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• 제9권3호
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• pp.288-294
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• 1999

솔더 범프를 사용하는 플립 칩 접속기술에서 범프와 칩 사이에 위치하는 금속 충들의 조합을 UBM(Under Bump Metallurgy)라고 부르며 이 UBM을 어떤 조합으로 사용하는 가에 따라 접속의 안정성이 크게 좌우된다. 본 연구에서는 UBM중에서 솔더 접착 층으로 사용되는 구리 층의 두께를 $1\mu\textrm{m}와 5\mu\textrm{m}$로 하는 한편 barrier 층으로 사용되는 금속 층을 Ti, Ni, Pd으로 변화시키면서 이들 UBM과 공정 납-주석 사이의 계면반응을 살펴보았다. 이를 위해 $100\mu\textrm{m}$ 크기의 솔더 범프를 전해도금법을 사용하여 제작하고 리플로 횟수와 시효시간에 따른 각 UBM에서의 금속간 화합물의 성장을 관찰하였다. $Cu_6Sn_5 \eta'$-상 금속간 화합물이 모든 조건에서 형성되었고 Cu층의 두께가 $5\mu\textrm{m}$로 두꺼운 경우에는 $Cu_3Sn \varepsilon$-상도 관찰되었다. Pd을 사용한 UBM 구조에서는 시효 처리시에 $Cu_6Sn_5$ 상 아래쪽에 $PdSn_4$상이 형성되었다. 또한 이들 계면에서의 금속간 화합물의 성장은 솔더 범프의 접속강도 값과 밀접한 관계를 가진다.

• Journal of Preventive Medicine and Public Health
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• 제47권2호
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• pp.84-93
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• 2014

Objectives: The incidence and survival rate of colorectal cancer in Korea are increasing because of improved screening, treatment technologies, and lifestyle changes. In this aging population, increases in economic cost result. This study was conducted to estimate the economic burden of colorectal cancer utilizing claims data from the Health Insurance Review and Assessment Service. Methods: Economic burdens of colorectal cancer were estimated using prevalence data and patients were defined as those who received ambulatory treatment from medical institutions or who had been hospitalized due to colorectal cancer under the International Classification of Disease 10th revision codes from C18-C21. The economic burdens of colorectal cancer were calculated as direct costs and indirect costs. Results: The prevalence rate (per 100 000 people) of those who were treated for colorectal cancer during 2010 was 165.48. The economic burdens of colorectal cancer in 2010 were 3 trillion and 100 billion Korean won (KRW), respectively. Direct costs included 1 trillion and 960 billion KRW (62.85%), respectively and indirect costs were 1 trillion and 160 billion (37.15%), respectively. Conclusions: Colorectal cancer has a large economic burden. Efforts should be made to reduce the economic burden of the disease through primary and secondary prevention.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.200-200
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• 2012

We investigated a flexible transparent film using the spinning multi-walled carbon nanotubes (MWCNTs). Spin-capable MWCNTs on iron catalyzed on a SiO2 wafer was grown by chemical vapor deposition, which was performed at $780^{\circ}C$ using C2H2 and H2 gas. The average diameter and length of MWCNTs grown on the substrate were ~15 nm and $250{\sim}300{\mu}m$, respectively. The MWCNT sheets were produced by continuously pulling out from well-aligned MWCNTs on a substrate. The MWCNT sheet films were produced simply by direct coating on the flexible film or grass. The thickness of sheet film was remarkably decreased by alcohol spraying on the surface of sheet. The alcohol splay increased transmittance and decreased electrical resistance of MWCNT sheet films. Single and double sheets were produced with sheet resistance of ~699 and ${\sim}349{\Omega}/sq$, respectively, transmittance of 81~85 % and 67~72%, respectively. The MWCNT sheet films were heated through the application of direct current power. The flexible transparent heaters showed a rapid thermal response and uniform distribution of temperature. In addition, MWCNT yarns were prepared by spinning a bundle of MWCNTs from vertically super-aligned MWCNTs on a substrate, and field emission from the tip and side of the yarns was induced in a scanning electron microscope. We found that the field emission behavior from the tip of the yarn was better than the field emission from the side. The field emission turn-on voltages from the tip and side of MWCNT yarns were 1.6 and $1.7V/{\mu}m$, respectively, after the yarn was subjected to an aging process. Both the configuration of the tip end and the body of the yarn were changed remarkably during the field emission. We also performed the field emission of the sheet films. The sheet films showed the turn on voltage of ${\sim}1.45V/{\mu}m$ during the field emission.

• 한국인터넷방송통신학회논문지
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• 제22권6호
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• pp.179-184
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• 2022

최근 4차 산업혁명 시대에 발맞춰 개방하는 공공데이터가 증가함에 따라 농업 공공데이터 또한 증가하고 있다. 현재 농업인 대다수가 친환경 인증과 기본형 공익직접지불사업을 이유로 영농일지를 작성하고 있다. 그러나 바쁜 농가에 고령화된 농촌 사회에서 영농일지를 작성하는 것은 힘든 일이다. 이 때문에 영농일지를 대리 작성하는 일이 일어나고 있다. 그러나 이 경우 친환경 인증과 기본형 공익직접지불사업에서 불이익을 받을 수 있다. 따라서 본 논문은 영농일지를 작성할 때 작물과 날짜를 통해 서버에 저장된 영농일지 데이터를 확인하고 사용자에게 적합한 영농일지 공공데이터를 찾아 자동으로 영농일지를 채움으로써 영농일지를 편리하게 작성하는 시스템을 제안한다.

• 한국임상약학회지
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• 제32권1호
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• pp.37-46
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• 2022

Background: Non-valvular atrial fibrillation (NVAF) is associated with ischemic stroke risk in the aging population. Observational studies have indicated beneficial effects of direct-acting oral anticoagulant (DOAC) against ischemic stroke compared to warfarin. This study aimed to investigate ischemic stroke incidence and bleeding risk in patients on DOAC therapy. Methods: Using the database of Korean Health Insurance Review and Assessment-Aged Patient Sample 2015, we conducted a retrospective cohort study. Study subjects with NVAF diagnosis and prescribed anticoagulants were enrolled. Propensity score (PS) matching by age, sex, comorbidities, and medications were used. The clinical outcomes were major adverse cerebro-cardiovascular events (MACCEs, ischemic stroke/systemic embolism, myocardial infarction, cardiac death) and bleeding events. A cox proportional hazard model analysis was performed to compare the outcomes with hazard ratio (HR) and 95% confidence interval (CI). Results: Total 4,773 elderly patients with NVAF were initially included. Four PS-matched groups including rivaroxaban vs. warfarin-only (n=1,079), dabigatran vs. warfarin-only (n=721), rivaroxaban vs. dabigatran (n=721), and switchers of warfarin to rivaroxaban vs. warfarin-only (n=287) were analyzed. Every group showed statistically similar results of MACCEs and bleeding events, except for the group of rivaroxaban vs. dabigatran. Rivaroxaban users showed higher risks of bleeding events than dabigatran users (HR 2.25, 95% CI 1.01-4.99). Conclusion: In the elderly patients with NVAF, efficacy and safety outcomes among oral anticoagulants including DOACs and warfarin were similar, while rivaroxaban are more likely to have higher bleeding risks than dabigatran. Further research using large size sample is needed.