• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2004년도 춘계학술발표대회
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• pp.997-1000
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• 2004

Boolean Satisfiability (SAT)는 전산학의 중요한 문제로서 SAT problem을 풀기 위한 많은 알고리즘과 도구들이 제안되어 왔다. 특히, 지난 몇 년 간 많은 발전을 이루어왔고, 하드웨어 검증과 모델 체킹 등의 분야에서 많이 적용되어 왔다. 여러 문제들을 Conjunctive Normal Form (CNF)로 표현하여 CNF의 특성을 이용하여 SAT 알고리즘이 발전되어 왔다. 그런데, 회로를 CNF로 표현할 때 몇 가지 문제점이 발생하는데 특히 CNF는 회로의 structural information 을 잃어버린다는 것이 큰 문제점이다. 이를 보완하기 위하여 회로의 structural information을 이용하기 위한 많은 연구가 진행되어 왔다. 이러한 대부분의 연구는 회로의 정보를 가지고 있다는 경우에 한정된다. 그러나, 하드웨어 검증에서 회로의 정보 없이 검증해야 하는 경우들도 발생한다. 이 논문은 회로의 정보를 가지고 있지 않을 때 CNF 만으로 회로의 structural information을 추론하는 방법을 제시한다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제35권11호
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• pp.661-670
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• 2008

만족가능성 처리기는 모델 검증 및 임베디드 프로그램 검증과 같이 소프트웨어 공학의 여러 분야에서 활용되고 있다. 만족가능성 처리기를 활용하기 위해서는 주어진 문제를 처리기의 입력인 CNF 형식으로 변환해야 한다. 그러나 이 형식은 소스코드나 소프트웨어 모델보다 표현력이 낮기 때문에 최적화된 변환이 요구된다. 본 논문에서는 "n개에서 인접된 $k{\leq}n$개 선택" 문제를 CNF형식으로 변환하는 최적화된 기법을 제시한다. 제안된 방법을 다양한 일본 퍼즐에 적용한 결과 우수한 성능이 입증되었다. 우리가 알고 있는 한, 인접성에 대한 최적화된 CNF 변환 연구는 거의 없다.

• Journal of the Korean Wood Science and Technology
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• 제42권2호
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• pp.119-129
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• 2014

This work undertook to prepare nanofibers of cellulose nanofibrils (CNF)/polyvinyl alcohol (PVA) composite by electrospinning, and characterize the electrospun composite nanofibers. Different contents of CNFs isolated from hardwood bleached kraft pulp (HW-BKP) by 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated oxidation were suspended in aqueous polyvinyl alcohol (PVA) solution, and then electrospun into CNF/PVA composite nanofibers. The morphology and dimension of CNFs were characterized by transmission electron microscopy (TEM), which revealed that CNFs were fibrillated form with the diameter of about $7.07{\pm}0.99$ nm. Morphology of the electrospun nanofiber observed by field-emission scanning electron microscopy (FE-SEM) showed that uniform CNF/PVA composite nanofibers were manufactured at 1~3% CNF contents while many beads were observed at 5% CNF level. Both the viscosity of CNF/PVA solution and diameter of the electrospun nanofiber decreased with an increase in CNF content. The diameter and its distribution of the electrospun nanofibers helped explain the differences observed in their morphology. These results show that the electrospinning method was successful in preparing uniform CNF/PVA nanofibers, indicating a great potential for manufacturing consistent and reliable cellulose-based nanofibrils for scaffolds in future applications.

• 한국정보과학회논문지:소프트웨어및응용
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• 제35권2호
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• pp.81-90
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• 2008

이진 변수의 기수 조건이란 여러 이진 변수 중에서 하나를 선택하는 것이다. 이러한 조건을 줄여서 BCC(Boolean Cardinality Constraint)라고 부른다. BCC는 소프트웨어 공학을 비롯해서 전산학의 다양한 분야에서 널리 사용되고 있다. 그래서 BCC를 CNF로 변환하는 효율적인 방법이 많이 연구되었다. 본 논문에서는 지금까지 제시된 변환 방법을 효율성과 유연성 측면에서 분석한다. 뿐만 아니라 이해하기 어려운 것으로 잘 알려진 CNF 절을 시각화하여 숨겨진 구조를 드러냄으로서 기존 분석과 차별화를 하였다. 분석 결과를 확인하기 위해서 다양한 비둘기-집 문제에 적용하였다. 그 결과 BCC를 다루는데 있어서 커멘더 변환 방법이 다른 방법보다 우수하였다.

• 공업화학
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• 제32권1호
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• pp.110-116
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• 2021

In this work, the surface of hydrophilic cellulose nanofibrils (CNFs) was modified precisely by varying amounts of cetyltrimethylammonium bromide (CTAB) to produce CNF-based particle surfactants. We found that a critical CTAB density was required to generate amphiphilic CTAB-grafted CNF (CNF-CTAB). Compared to pristine CNF, CNF-CTAB was highly efficient at stabilizing oil-in-water Pickering emulsions. To evaluate their effectiveness as particle surfactants, the surface coverage of oil-in-water emulsion droplets was determined by changing the CNF-CTAB concentration in the aqueous phase. Furthermore, styrene-in-water stabilized by CNF-CTAB surfactants was thermally polymerized to produce CNF-stabilized polystyrene (PS) particles, offering a great potential for various applications including pharmaceuticals, cosmetics, and petrochemicals.

• Advances in aircraft and spacecraft science
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• 제4권6호
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• pp.729-744
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• 2017

This investigation highlights rationale of electrically conductive nano adhesives for its essential application for Electromagnetic Interference (EMI) Shielding in satellites and Lightning Strike Protection in aircrafts. Carbon Nano Fibres (CNF) were functionalized by electroless process using Tollen's reagent and by Plasma Enhanced Chemical Vapour Deposition (PECVD) process by depositing silver on CNF. Different weight percentage of CNF and silver coated CNF were reinforced into the epoxy resin hardener system. Scanning Electron Microscopy (SEM) micrographs clearly show the presence of CNF in the epoxy matrix, thus giving enough evidence to show that dispersion is uniform. Transmission Electron Microscopy (TEM) studies reveal that there is uniform deposition of silver on CNF resulting in significant improvement in interfacial adhesion with epoxy matrix. There is a considerable increase in thermal stability of the conductive nano adhesive demonstrated by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Four probe conductivity meters clearly shows a substantial increase in the electrical conductivity of silver coated CNF-epoxy composite compared to non-coated CNF-epoxy composite. Tensile test results clearly show that there is a significant increase in the tensile strength of silver coated CNF-composites compared to non-coated CNF-epoxy composites. Consequently, this technology is highly desirable for satellites and EMI Shielding and will open a new dimension in space research.

• 공업화학
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• 제28권2호
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• pp.257-262
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• 2017

본 연구에서는 electrospinning method의 공정변수를 다르게 하여 CNF (carbon nanofiber)를 제조하였다. 제조된 CNF의 섬유의 형태, 직경 등의 변화를 SEM 분석을 통해 관찰하였으며 인가전압, TCD (tip to collecor distance), 고분자 용액의 농도, 열처리 단계가 CNF 물성을 형성함에 있어 주요한 영향인자임을 확인하였다. 또한 서로 다른 물성으로 제조된 CNF를 전기분해 공정의 전극으로 적용하여 toluene의 제거 효율을 비교하였고, 이를 통해 anode 뿐만 아니라 cathode 역시 전기분해 효율에 직접적인 영향을 미침을 확인하였다.

• 한국미생물·생명공학회지
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• 제50권2호
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• pp.283-292
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• 2022

Colibactins (clb) and Cytotoxic Necrotizing Factors (cnf) are virulence factors that impact cell cycle through cellular differentiation, proliferation, and apoptosis. Urinary tract infections (UTIs) are the most common among type of infection among outpatients, with a lifetime incidence of about 60-65% in adult females. Here, we sought to isolate uropathogenic Escherichia coli (UPCE) from urine specimens and investigates the prevalence of clb A, B and cnf 1, 2 genes among these isolates. A total of 110 E. coli isolates were collected from patients with UTIs. All the isolates were examined for their hemolytic activity and only 46 isolates showed a halo zone of hemolysis on blood agar. The collected UPEC isolates were screened for the existence of clb A, B and cnf genes. The results revealed that out of 110 isolates, 28 harbored the clbA gene, 40 harbored clb B, and 24 isolates harboured cnf1. 13 isolates harbored clbA, clbB, and cnf1 genes, while no cnf2 gene was detected among isolates. The molecular detection revealed that 8 out of 28 hemolytic isolates carrying the clbA, 11 out of 40 were carrying clbB, 1 out of 24 were carrying cnf 1, and 5 out of 9 carrying clbA+clbB. Furthermore, 7 out of 13 isolates were hemolytic and carrying clbA, clbB, and cnf1 genes. Finally, we investigated the cytotoxicity of E. coli harboring clb and cnf genes, eukaryotic REF cells were exposed to E. coli producing colibactin, which induces DNA damage and leads to cell cycle arrest, senescence and death.

• 펄프종이기술
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• 제48권2호
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• pp.91-98
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• 2016

Cellulose nanofibrils (CNF) was made from oil palm trunk (OPT) with soda-anthraquinone pulping, chlorine dioxide bleaching, carboxymethylation, followed by mechanical grinding. Size of this CNF was 16-40 nm of width confirmed by TEM. To evaluate CNF from OPT as cosmetics raw materials for moisturizing component, water holding properties was compared with hyaluronic acid and collagen. CNF from OPT had better water holding property than collagen or hyaluronic acid whether phenoxyethanol was added as antiseptic or without additive.

• International Journal of Industrial Entomology and Biomaterials
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• 제26권2호
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• pp.81-88
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• 2013

Wet-spun silk fibers have attracted the attention of many researchers because of 1) the unique properties of silk as a biomaterial, including good biocompatibility and cyto-compatability and 2) the various methods available to control the structure and properties of the fiber. Cellulose nanofibrils (CNFs) have typically been used as a reinforcing material for natural and synthetic polymers. In this study, CNF-embedded silk fibroin (SF) nanocomposite fibers were prepared for the first time. The effects of CNF content on the rheology of the dope solution and the characteristics of wet-spun CNF/SF composite fibers were also examined. A 5% SF formic acid solution that contained no CNFs showed nearly Newtonian fluid behavior, with slight shear thinning. However, after the addition of 1% CNFs, the viscosity of the dope solution increased significantly, and apparent shear thinning was observed. The maximum draw ratio of the CNF/SF composite fibers decreased as the CNF content increased. Interestingly, the crystallinity index for the silk in the CNF/SF fibers was sequentially reduced as the CNF content was increased. This phenomenon may be due to the fact that the CNFs prevent ${\beta}$-sheet crystallization of the SF by elimination of formic acid from the dope solution during the coagulation process. The CNF/SF composite fibers displayed a relatively smooth surface with stripes, at low magnification (${\times}500$). However, a rugged nanoscale surface was observed at high magnification (${\times}10,000$), and the surface roughness increased with the CNF content.