• Clean Technology
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• v.19 no.4
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• pp.401-409
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• 2013

BBiodegradable polymers have attracted great attention because of the increased environmental pollution by waste plastics. In this study, PLA (polylactic acid)/Clay-20 (Cloisite 20) and PLA (polylactic acid)/PBS (poly(butylene succinate)/Clay-20 (Cloisite 20) nanocomposites were manufactured in a twin-screw extruder. Specimens for mechanical properties of PLA/Clay-20 and PLA/PBS (90/10)/Clay-20 nanocomposites were prepared by injection molding. Thermal, mechanical, morphological and raman spectral properties of two nanocomposites were investigated by differential scanning calorimetry (DSC), tensile tester, scanning electron microscopy (SEM) and raman-microscope spectrophotometer, respectively. In addition, hydrolytic degradation properties of two nanocomposites were investigated by hydrolytic degradation test. It was confirmed that the crystallinity of PLA/Clay-20 and PLA/PBS/Clay-20 nanocomposite was increased with increasing Clay-20 content and the Clay-20 is miscible with PLA and PLA/PBS resin from DSC and SEM results. Tensile strength of two nanocomposites was decreased, but thier elongation, impact strength, tensile modulus and flexural modulus were increased with an increase of Clay-20 content. The impact strength of PLA/Clay-20 and PLA/PBS/Clay-20 nanocomposites with 5 wt% of Clay-20 content was increased above twice than that of pure PLA and PLA/PBS (90/10). The hydrolytic degradation rate of PLA/Clay-20 nanocomposite with 3 wt% of Clay-20 content was accelerated about twice than that of pure PLA. The reason is that degradation may occur in the PLA and Clay-20 interface easily because of hydrophilic property of organic Clay-20. It was confirmed that a proper amount of Clay-20 can improve the mechanical properties of PLA and can control biodegradable property of PLA.

• Microbiology and Biotechnology Letters
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• v.38 no.4
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• pp.373-378
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• 2010

Studies on standardization and quality upgrade of nuruk which is a basic component in brewing are required to increase the quality level of Korean traditional rice wines and to develop the technology for practical use of it. It is important to isolate best strains, to improve the properties and effectively preserve them for brewing industry. In this study, 16 commercial nuruk samples were obtained from the commercial markets located in Chungcheong areas in Korea. 174 fungal strains were isolated from the samples on DG18 medium using a dilution plating method and then screened for enzyme activity and acid production. The active strains were identified based on the morphological characteristics and ITS sequence analysis. Out of 174 strains, 12 strains showed high amylase activity. Especially, Rhizopus sp. CN084, CN174, Aspergillus sp. CN161 and Mycocladus sp. CN042 showed high saccharogenic power and dextrinogenic enzyme activity on cooked wheat bran medium. On the other hand, Aspergillus sp. CN010, CN161, Rhizopus sp. CN105, CN168 and Rhizomucor sp. CN088 produced high acid production on the same medium. Our results showed that the active strains may be used as microbial sources for nuruk starter with good quality in brewing.

• Restorative Dentistry and Endodontics
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• v.33 no.3
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• pp.235-245
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• 2008

The aim of this study was to develop a method for measuring the slumping resistance of resin composites and to relate it to the rheological characteristics. Five commercial hybrid composites (Z100, Z250, DenFil, Tetric Ceram, ClearFil) and a nanofill composite (Z350) were used to make disc-shaped specimens of 2 mm thickness. An aluminum mold with square shaped cutting surface was pressed onto the composite discs to make standardized imprints. The imprints were light-cured either immediately (non-slumped) or after waiting for 3 minutes at $25{\circ}C$ (slumped). White stone replicas were made and then scanned for topography using a laser 3-D profilometer. Slumping resistance index (SRI) was defined as the ratio of the groove depth of the slumped specimen to that of the nonslumped specimen. The pre-cure viscoelasticity of each composite was evaluated by an oscillatory shear test and normal stress was measured by a squeeze test using a rheometer. Flow test was also performed using a flow tester. Correlation analysis was performed to investigate the relationship between the viscoelastic properties and the SRI. SRI varied between the six materials (Z100 < DenFil < Z250 < ClearFil < Tetric Ceram < Z350). The SRI was strongly correlated with the viscous (loss) shear modulus G' but not with the loss tangent. Also, slumping resistance was more closely related to the resistance to shear flow than to the normal stress. Slumping tendency could be quantified using the imprint method and SRI. The index may be applicable to evaluate the clinical handling characteristics of composites.

• Restorative Dentistry and Endodontics
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• v.36 no.2
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• pp.108-113
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• 2011

Objectives: To determine the effect of the spectral output of single and dual-peak light emitting diode (LED) curing lights on the microhardness and color stability of commercial resin composites formulated with camphorquinone and alternative photoinitiators in combination. Materials and Methods: Three light-polymerized resin composites (Z100 (3M ESPE), Tetric Ceram (Ivoclar Vivadent) and Aelite LS Posterior (Bisco)) with different photoinitiator systems were used. The resin composites were packed into a Teflon mold (8 mm diameter and 2 mm thickness) on a cover glass. After packing the composites, they were light cured with single-peak and dual-peak LEDs. The Knoop microhardness (KHN) and color difference (${\Delta}E$) for 30 days were measured. The data was analyzed statistically using a student's t-test (p < 0.05). Results: All resin composites showed improved microhardness when a third-generation dual-peak LED light was used. The color stability was also higher for all resin composites with dual-peak LEDs. However, there was a significant difference only for Aelite LS Posterior. Conclusions: The dual-peak LEDs have a beneficial effect on the microhardness and color stability of resin composites formulated with a combination of camphorquinone and alternative photoinitiators.

• Clinical and Experimental Reproductive Medicine
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• v.32 no.3
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• pp.231-242
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• 2005

연구목적: 본 연구는 아직 그 기능이 파악되지 않은 탈유비퀴틴효소 중 하나인 HIDE에 대한 기본적인 생화학적 특징과 고환에서의 발현 양상을 파악하고 있다. 연구재료 및 방법: 인간의 HIDE 유전자를 클로닝하여 효소활성이 있는지 세포 외 실험을 통해 확인하였고, 아미노산 서열을 분석하여 진화상 보존된 부분을 찾아 그 기능을 파악한 다음 HSP90과의 상호작용을 공동면역침전반응으로 확인하였다. HIDE의 조직별 발현양상을 파악하기 위해서 인간과 쥐의 RNA 블롯과 쥐의 단백질 블롯을 이용하여 각각 노던 블롯팅과 웨스턴 블롯팅을 수행하여 고환에서 많이 발현된다는 것을 알았고 이 사실을 바탕으로 쥐의 고환을 절개하여 면역조직화학반응으로써 고환 내의 HIDE 단백질의 발현양상을 파악하였다. 결　과: HIDE는 세포 외에서 유비퀴틴 잔기를 제거하는 탈유비퀴틴 활성이 있으나 세포 내에서 전체적인 유비퀴틴 복합체를 줄여주는 효과는 없었다. HIDE는 HSP90이라는 분자 샤페론과 상호작용한다. HIDE의 전사체는 고환에서 가장 많이 발현되며 다른 조직에서도 소량 발현된다. HIDE의 단백질은 웨스턴 블롯상에서 고환에서만 확인되었다. 고환 내에서의 HIDE의 발현양상은 왕성한 감수분열을 하는 정모세포에서 높았으며 지지세포나 정조세포에는 발현되지 않았다. 결　론: HIDE는 분자 샤페론 HSP90과 상호작용하며 고환 내의 감수분열 중인 세포에서 많이 발현되는 것으로 보아 감수분열이나 정자형성에 관여하는 것으로 보인다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.513-519
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• 2021

Metallic suture anchors are very useful and common fixation devices that are inserted into the target bone to sustain the tendon of a patient with musculus supraspinatus tendon ruptures. On the other hand, the presence of a metallic material prosthesis, such as a metal suture anchor, causes severe MR imaging artifacts, including field distortion, signal loss, and failure of fat suppression. The difference in magnetic susceptibility between metal and other organic materials causes magnetic field distortion surrounding the prosthesis. The resulting magnetic field inhomogeneity makes the images with a lower signal-to-noise ratio and distortion. For a patient with a suture anchor implanted, MR imaging is the golden standard for determining the postoperative prognosis, and a fat-saturation sequence is one of the imaging methods most affected by metal-induced artifacts. In this study, three fat-saturation sequences were compared. Artifact quantification and contrast comparison between the supraspinatus tendon and the surrounding muscle were presented. The images obtained using the STIR pulse sequence showed fewer susceptibility artifacts and better visibility in the supraspinatus tendon and the tissue area. Therefore, the STIR sequence is the most appropriate fat-saturation imaging method for patients with a metallic prosthesis.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.219-224
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• 2019

Purpose: The image registration of radiographic image and digital surface data is essential in the computer-guided implant guide system. The purpose of this study was to examine the effects of using micro-screw on the working time and convenience of operators in the process of image matching for guided implant surgery. Materials and methods: A mandibular dental model was prepared in partial edentulism for Kennedy class I classification. Two micro-screws were placed on the each side of retromolar area. Radiographic and scan images were taken using computed-tomography and digital scanning. The images were superimposed by 12 operators in software in two different conditions: using remaining teeth image alone and using teeth and micro-screws images. Working time, operator convenience and satisfaction were obtained, and analyzed using the Mann-Whitney U test (${\alpha}=.05$). Results: The working time was not statistically different between image registration conditions (P>.05); however, operator convenience and satisfaction were higher in the teeth and micro-screw assisted condition than in the teeth-alone assisted condition (P<.001). Conclusion: The use of micro-screw for the image registration has no effect in working time reduction, but improves operator convenience and satisfaction.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.4
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• pp.70-77
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• 2023

Fine dust is a cause of serious ecological problems, and fugitive dust generated from construction sites is a major source of fine dust in Korea. However, at construction sites, including concrete manufacturing industry sites, measurements are rarely made at the fugitive dust generation stage, and passive removal methods are the majority. Therefore, in this study, a fugitive dust measurement method suitable for managing fugitive dust generated during aggregate unloading in the concrete manufacturing industry sites was selected. In addition, the purpose was to analyze the amount of fugitive dust reduction according to the operation of the reduction system by applying the automatic fugitive dust reduction system to the aggregate unloading site. As a result, the reliability of the light scattering method was secured through the comparative measurement of the beta-ray absorption method and the light scattering method, and the light scattering method correction coefficient was calculated and applied to the measured value of the fugitive dust particle mass concentration at the concrete manufacturing industry sites. In addition, the fugitive dust reduction rate according to the operation of the automatic fugitive dust reduction system was derived.

• Conservation Science in Museum
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• v.29
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• pp.47-64
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• 2023

Daehye Bogakseonsaseo (Letters of Master Bogak) in the possession of the National Museum of Korea is a Goryeo-era book produced in 1387, which was acquired in 2005 in a state of severe general damage. Subsequently, its production techniques and materials were examined using bibliographical characteristics and scientific analysis, based on which an overall conservation treatment was carried out. Janghwang(mounting) in bibliographical characteristics is a five-hole-stitch binding (五針眼線裝本), a single-lined rectangular box (四周單邊), and no column lines. The conservation treatment was examined in two aspects: the basic form and the conservation treatment process. The book is composed of the outer cover, original cover, end paper, and inner paper of 0.04-0.07mm thick, which is significantly thinner than general book paper. The conservation treatment was applied after the entire book was disassembled, based on the assessment that both the cover and the inner sheets of paper were in a dire condition due to deterioration. The conservation treatment comprised of the process of disassembly, cleaning, reinforcement of defective parts, scanning, and binding, with a paulownia box made for its storage. At the time of disassembly, samples were made for the inner sheets and the book string in order to conduct fiber identification. The fibers were identified using Safranin and C-stains. Safranin staining identified a thick fiber wall, in addition to cross-marking, dislocation, and transparent membranes. C-stain staining identified the fiber as mulberry, given the dark red residue. The book strap has a flat, circular cross-section, and was identified as cotton fiber, since a lumen was observed in the center.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.46-46
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• 2022

본 연구의 목적은 약용과 식용으로서의 활용도가 높은 일당귀[Angelica acutiloba (Siebold & Zucc.) Kitagawa]의 GA₃농도에 따른 생육특성을 확인하고, 최적의 재배기술 개발 및 지속가능한 안정적인 작물생산에 대한 기초자료의 제공에 있다. 연구재료는 강원도 태백시에 위치하는 일당귀 재배농가에서 2021년 10월에 채종한 종자를 구입하였고, 영주시 풍기읍에 위치한 연구온실에서 연구를 수행하였다. 일당귀의 종자를 증류수에 48시간 침지 후 GA₃농도 4조건(50 ppm, 100 ppm, 500 ppm, 1,000 ppm)에 24시간 처리 후 72구 포트에 파종 후 출아율과 생육특성을 조사하였다. 연구결과 일당귀 종자는 16일이 경과한 시점부터 출아를 시작하였고, 500 ppm처리구에서 73.3%로 가장 높은 출아율을 나타냈다. 생육특성조사는 출아 후 40일(1차)과 80일(2차) 경과된 시점에서 총 2회를 수행하였는데 1차 생육조사에서는 주근길이와 직경을 제외한 모든 생육특성에서 처리구별 생육의 차이가 확인되지 않았으나 2차 생육조사에서는 지상부와 지하부의 모든 생육특성에서 처리구별 생육의 차이가 확인되었다. 잎수(6.3개)와 주근길이(4.26 cm)는 500 ppm처리구에서 가장 높은 생육량을 나타냈고, 지상부 높이(21.81 cm), 잎길이(9.0 cm), 잎너비(10.77 cm), 주근직경(5.71 mm)은 1,000 ppm처리구에서 가장 높은 생육량을 나타냈다. 따라서 GA₃ 처리에 따른 일당귀의 생육특성은 생육초기보다 후기로 갈수록 발현량이 높게 나타나는 것으로 판단된다. 또한 저농도의 GA₃처리보다 500-1,000 ppm 사이의 처리농도가 적합한 것으로 판단되며, 추후 일당귀의 유용성분 분석을 통한 이화학적 연구가 추가된다면 최적의 재배기술 확립을 통한 안정적인 작물 생산에 기여할 수 있을 것이라 사료된다.