Electropulsing Treatment on Enhancement of Electrical Conductivity of Screen-Printed Ag Wire

Ju‑Won Park,Howook Choi,Hwangsun Kim,Simoon Sung,Hye‑Jin Jeong,Il Kim,Jaeseok Gong,Sung‑Tae Hong,Heung Nam Han 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

The effect of high electric current density on the sintering of Ag wires manufactured by screen printing is evaluated throughelectrical resistivity analysis and microstructure observation. Different forms (continuous and pulsed) of electric currentwith different current densities are applied to the specimens. Conventional heat treatment is also performed as a controlgroup to examine the athermal effect of electropulsing treatment. Compared to the conventional heat treatment, the resistivityis reduced more under the electropulsing treatment with continuous current for the same temperature and treatment time.Also, the process time of electropulsing treatment can be reduced by applying a pulse form of high density current insteadof continuous current without losing the benefit of enhanced reduction of resistivity. The microstructural observationsobtained from high angle annular dark field scanning transmission electron microscope and a digital precession instrumentclearly show that necking connecting the crystals is formed more firmly under electric current. In addition, the temperaturechange of Ag wire and substrate is calculated according to the change of the resistivity when the electric current is appliedto confirm the reliability.

광조사 방식이 복합레진의 중합과 누출에 미치는 영향

박종진,박정원,박성호,박주명,권태경,김성교 大韓齒科保存學會 2002 Restorative Dentistry & Endodontics Vol.27 No.2

The aim of this study was to investigate the effect of light irradiation modes on polymerization shrinkage, degree of cure and microleakage of a composite resin. VIP^™ (Bisco Dental Products, Schaumburg, IL, USA) and Optilux 501^™(demetron/ Kerr, Danbury, CT, USA) were used for curing Filtek^™ Z-250(3M Dental Products, St. Paul., MN, USA) composite resin using following irradiation modes: VIP^™ (Bisco) 200mW/cm^2 (V2), 400mW/cm^2 (V4), 600mW/cm^2 (V6), Pulse-delay (200 mW/cm^2 3 seconds, 5 minutes wait, 600mW/cm^2 30seconds, VPD) and Optilux 501^™ (Demetron/Kerr) C-mode (OC), R-mode (OR). Linear polymerization shrinkage of the composite specimens were measured using Linometer (R&B, Daejeon, Korea) for 90 seconds for V2, V4, V6, OC, OR groups and for up to 363 seconds for VPD group (n=10, each). Degree of conversion was measured using FTIR spectrometer (IFS 120 HR, Bruker Karlsruhe, Germany) at the bottom surface of 2 mm thick composite specimens. V2, V4, V6, OC groups were measured separately at five irradiation times (5, 10, 20, 40, 60 seconds) and Or, VPD groups were measured in the above mentioned irradiation modes (n=5, each). Microhardness was measured using Digital microhardness tester (FM7, Future-Tech Co., Tokyo, Japan) at the top and bottom surfaces of 2mm thick composite specimens after exposure to the same irradiation modes as the test of degree of conversion(n=3, each). For the microleakage test, class V cavities were prepared on the distal surface of the ninety extracted human third molars. The cavities were restored with one of the following irradiation modes: V2/60 seconds. V4/40 seconds, V6/30 seconds, VPD, OC and OR. Microleakage was asessed by dye penetration along enamel and dentin marigns of cavities. Mean polymerization shrinkage, mean degree of conversion and mean microhardness values for all groups at each time were analyzed using one-way ANOVA and Duncan's multiple range test, and using chisquare test for microleakage values. The results were as follows: ·Polymerization shrinkage was increased with higher light intensity in groups using VIP^™(Bisco) : the highset with 600mW/cm^2, followed by Pulse-delay, 400mW/cm^2 and 200mW/cm^2 groups. The degree of polymerization shrinkage was higher with Continuous mode than with Ramp mode in groups using Optilux 501^™ (Demetron/Kerr). ·Degree of conversion and microhardness values were higher with higher light intensity. The final degree of conversion was in the range of 44.7 to 54.98% and the final microhardness value in the range of 34.10 to 56.340. ·Microleakage was greater in dentin margin than in enamel margin. Higher light intensity showed more microleakage in dentin margin in groups using VIP^™ (Bisco). The microleakage was the lowest with Continuous mode in enamel margin and with Ramp mode in dentin margin when Optilux 501^™ (Demetron/Kerr) was used.

흡연에 의한 급성 호산구성 폐렴 2예

박종빈,김학렬,주현준,유태양,신성남,신정현,송정섭,황기은,김소영,양세훈,정은택 圓光大學校 醫科學硏究所 2008 圓光醫科學 Vol.23 No.2

최근 흡연을 시작한 젊은 성언에서 급성 호산구성 폐렴의 발생에 대한 증례가 보고되고 있다. 급성 호산구성 폐렴은 대개 발열을 동반하기 때문에 초기에는 감염성 폐렴으로 잘못 진단, 치료되는 경우가 많다. 아직 정확한 병태 생리 및 조직학적 소견은 밝혀져 있지 않지만 병력 청취 및 임상 양상, 방사선 소견의 관찰을 통해 급성 호산구성 폐렴을 의심하고, 진단을 위해 기관지 폐포 세척액 검사를 시행한다면 좀 더 쉽게 진단 내릴 수 있을 것이다. 본 저자들은 최근 처음 시작한 흡연에 의해 발생한 급성 호산구성 폐렴을 진단하고, 스테로이드를 투여하여 성공적으로 치료한 환자 2예를 경험하였기에 이를 문헌 고찰과 함께 보고하는 바이다. Acute eosinophilic pneumonia(AEP) is characterized by acute febrile respiratory illness associated with diffuse pulmonary infiltration and pulmonary eosinophilia. The specific etiology for acute eosinophilic pneumonia is elusive. By some investigators, cigarette smoking is suggested as a causative substance which can cause AEP. In recent, the authors experienced two cases of AEP following cigarette smoking. Both cases had characteristic features including age around 20 years, new onset smoking before occurance of AEP, diffuse infiltration on chest radiography, pulmonary eosinophilia based on bronchoalveolar lavage and acute improvement after steroid therapy. These clinical features are resemble with previous smoking induced AEP case reports. Base on these clinical features, cigarette smoking associated AEP could be diagnosed more easily.

시멘트 콘크리트의 건조수축균열 특성

박제선,윤경구,이주형,김태환,정원경 강원대학교 부설 석재복합신소재 제품연구센터 2000 석재연 논문집 Vol.5 No.-

콘크리트는 본질적으로 인장강고와 휨강도가 약하며 취성적 성질을 나타내는 결점을 가지고 있으므로 이를 보강할 목적으로 콘크리트에 섬유를 혼입한 섬유보강 콘크리트가 크게 각광받고 있다. 특히 폴리프로필렌 섬유보강은 모르타르 및 콘크리트가 건조나 동해에 의해 수축될 때 구속에 의해 발생되는 인장응력 및 균열을 제어하고 인성의 증가와 충격, 마모, 피로에 대한 저항성, 내구성을 증대시키는 장점을 가지는 것으로 보고 되고 있다. 1축으로 구속된 건조수축의 구속으로 인한 조강형 콘크리트의 잔류응력을 선형모델을 이용하여 예측할 수 있었고 조강형 콘크리트에 섬유보강으로 인한 건조수축 제어효과는 일반큰코리트에 비해 효과가 매우 큰 것으로 나타났다. 따라서 폴리크로필렌 섬유의 혼입으로 인해 콘크리트의 균열제어가 가능하며, 균열 폭이 큰 균열보다는 많은 미세 균열을 유도하는 것을 알 수 있었다. 섬유보강 조강형 큰크리트의 동결융해저항특성은 거의 동해의 손상을 받지 않으며 좋은 내구성을 유지하고 있는 것으로 나타났다. 이는 불규칙하게 배향된 섬유가 공극수의 이동을 효과적으로 제어함으로써 메트릭스 내의 팽창압으로 인한 파괴를 최대한 줄였기 때문이라고 보여진다. 표면손상과 박리저항에 매우 우수하며 저항성을 증진시키는 효과가 뛰어남을 확인할 수 있었다. 따라서, 내구적 측면의 유지, 보수에 있어서도 섬유보강은 그 효과가 큰 것으로 나타났다. To improve the brittle nature of concrete, discrete fibers can be adapted in concrete. Since polypropylene fiber has many advantages in many points on its chemical stability and good durability, its usages have been increased gradually. It has been reported than polypropylene fibers can not only control restrained tensional stresses and cracks, but also increase toughness, resistance to impact, corrosion, fatigue, and durability. Although the polypropylene fiber reinforced concretes with ordinary cement have been studied so much, those with very early strength concretes have not studied at all. Therefore, it is necessary to initiate and conduct the researches for the polypropylene fiber reinforced very early strength concretes which has enough workability and durability. This study of polypropylene fiber reinforced very early strength concrete focused on the investigation each material's effect into strength development with analysis of restrained shrinkage properties with one-dimensional concrete members. The results showed that more optimized mixture combinations could be selected in very early strength concrete by incorporating polypropylene fibers, keeping in same strength levels at urgent repair works. The formation of needle-shape ettringite helps the early strength development, specially at flexural and this enables the repaired concrete structures or pavements to be opened to traffic after 3 hours of concrete placement. A residual stress of early strength concrete caused by one-dimensional restrained drying shrinkage was predicted from linear model. the control of shrinkage crack by fiber reinforcement at early strength concrete was better than that of ordinary portland cement concrete because of bridging effect of fiber at early age and resulting of more hair cracks rather than fewer wider cracks. As a results, this dissertation clearly validated the fiber reinforcement on the strength development and durability of polypropylene fiber reinforced very early strength concrete, and characteristic of restrained shrinkage. The proposed optimized concrete mixtures might be satisfactory applied at the repair works in fields, because of its durability and crack control capacity against freeze-thaw and contraction at early age, respectively.

피혁슬러지 고형화시 시멘트 혼화제의 영향

주소영,박상찬,전태성,손종렬,김태영 대한위생학회 2003 대한환경위생공학회지 Vol.18 No.4

The cement-based system among S/S(Solidification/Stabilization) is widely used to treat hazardous wastes. In this study, tannery sludge was solidified to evaluate the stabilization effects of using admixtures in the cement-based S/S. Fly ash as substitute also used to increase the strength of the S/S of hazardous waste. The compressive strength measurement and leaching experiment of chromium metal of solidified mortar were carried out to compare and evaluate the physical and chemical characteristics of solidified hazardous waste sludge. From the result of this study, there was increased of compressive strength by using AEW-3(early-hardening AE water reducing agent), and leaching concentration of chromium became low enough to satisfy the regulatory criteria. The successful solidification for the organic contaminant and heavy metal in hazardous waste should enable to treat by cement-based system using early-hardening AE water reducing admixture and fly ash as substituted cement.

소아청소년과의사의 영유아기 구강건강 관리에 대한 인식도 조사

주태준,박호원,이주현,서현우 大韓小兒齒科學會 2009 大韓小兒齒科學會誌 Vol.36 No.3

국민건강보험공단에서 실시하는 영유아 건강검진은 5회의 일반검진과 2회의 구강검진으로 구성되어 있다. 하지만 9개월 영유아 건강검진 시 구강건강 상담 및 교육은 일반의사가 담당하도록 되어 있어 이를 주로 담당하게 될 소아청소년과의사의 구강건강 상담 항목에 대한 지식이 필요한 상황이다. 이번 조사의 목적은 소아청소년과 전문의나 전공의를 대상으로 영유아기 구강건강교육에 대한 인식도를 알아보는 것으로 150명의 설문을 분석해 다음과 같은 결론을 얻었다. 1. 조사 대상자의 대부분은 유아기우식증으로 인한 치과 의뢰 경험이 있었고, 절반 이상의 응답자는 영유아 환자에 대해 구강검사를 시행하지 않고 있었다. 2. 조사 대상 소아청소년과의사들의 첫 치과방문 시기에 관한 적절한 인식도가 확립되지 않았다. 3. 영유아 건강검진 중 구강건강 교육 항목에 대한 인지도가 전반적으로 부족하였다. 이에 대한 교육의 강화가 필요하다. 4. 영유아 구강질환 예방을 위한 의과계의 관심과 더불어 치과계와의 협조가 필요하리라 생각 된다. For prevention of ECC, the Korean Academy Of Pediatric Dentistry(KAPD) advocate that Children should be seen as early as 6 months of age after the first tooth erupts, or 12 months of age. Pediatrics have increased access to new mothers and children 6 to 12 months while dentists does not see young children unless there are urgent problems. Therefore, they have an opportunity to impact infant oral health care. This study's purpose was to examine pediatricians' awareness and experience about infant oral health care. For the study, we surveyed of 150 pediatricians in korea. The survey comprised 10 questions related to infant oral health care and the recommended age a child go for their first dental visit. The results were as follows: 1. Most respondents had been referred children to a dentist for treating ECC and more than half of respondents reported that they did not do oral examination in their practice. 2. The majority of surveyed pediatricians are not advising patients to see the dentist by 1 year of age. 3. The surveyed pediatrician's awareness of infant oral health care is insufficient. The oral health education should be reinforced. 4. There is a need for increased infant oral health care education in the medical and dental communities.

브로콜리 줄기의 callus배양 및 항노화 효과

박태진 ․ 이상민 ․ 조준환 ․ 남수호․ 신주은 ․ 김대환 ․ 이인순 ․ 박흠대 대구대학교 산업기술연구소 2018 産業技術硏究 Vol.29 No.2

Broccoli (Brassica oleracea var. italica) is well known of excellent antioxidant food so that we researched on its anti-aging and callus differentiation from the tissue of broccoli stem by MS medium with exo-phytohormone as IAA, kinetin. The functional materials of callus tissue were extracted with water and 70% EtOH after 16 days progressed callus formation. As a result, callus differentiation and formation were showed higher efficiency at B5 condition medium (0.1 mg/L IAA, 0.4 mg/L). The callus cultured on B3, B6 and B7 medium were observed the reaction of enzymatic browning to callus tissue. The anti-aging effect on the extract was experiment with DPPH radical scavenging and catalase(CAT). The activity of DPPH radical scavenging was showed high value in water extract of B1, B6, B8, B9 and was increased depending on sample concentration. However, in case of the extract of 70% EtOH, DPPH activity was showed different effect depending on the sample kind. CAT activity was found the highest enzyme unit in the extract of natural broccoli and B1(no add exo-phytohormone). It is to express that a broccoli itself is great food for anti-aging. Therefore, callus formation of broccoli considers having no economic efficiency to do development of anti-aging product.

스티렌 현탁 중합반응에서 폭주반응 해석

박형일,신석주,이헌창,장서일,김태옥 한국산업안전학회 2002 한국안전학회지 Vol.17 No.3

The runaway reaction was analyzed experimently and theoretically at the batch styrene suspension polymerization process. In the experiments, the reaction temperature with time was measured at various experimental conditions. According to the experimental results, the risk of the runaway reaction was increased with increasing the ratio of the monomer(styrene, M) to the dispersion medium(water, W), the concentration of the initiator(BPO), and the monomer mass, respectively. And simulation results showed that the runaway reaction was significantly affected by the reaction rate constant of the propagation and that the phenomena of the runaway reaction occurred at about 70% conversion. Also, we found that the runaway reaction did not occur under the operation condition of below 0.5 for M/W, approximate 3 wt% BPO, and below 75℃ for the cooling temperature.

有限要素法에 依한 프레임의 非線形 解析

朴英錫,鄭泰周 명지대학교 공학기술연구소 1986 공학기술연구소 논문집 Vol.1 No.-

A numerical procedure is presented to perform static analysis of the elastic frame using the finite element method. The governing equilibrium equations are derived by the strain energy and modified Newton-Raphson procedure is used to solve the nonlinear system of algebraic equation. Both the end force equations and stiffness matrices for the beam element are given in the appendix. The developed beam element can be used to nonlinear analysis of frame in plane and space. It provides for both the tersional deformation and elongation of beam, and permits the use of different physical properties in each principal direction. The validity of this method is demonstrated by comparing the results obtained by the present method with other results. In exampls, the results of numerical calculation are given in tabular form for the cantilever beam with a transversal point load and pinned-fixed square diamond frame and the beam curved in space is analysed.

남성 건강검진 수진자에서 간기능 장애 및 비알코올성 지방간과 대사 증후군과의 관련성

최태성,유재영,김진석,장은철,박주언,김병익 순천향의학연구소 2006 Journal of Soonchunhyang Medical Science Vol.12 No.2

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