• Korean Circulation Journal
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• 제54권3호
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• pp.113-123
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• 2024

Background and Objectives: Previous studies have reported an association between impaired renal function and poor outcomes after radiofrequency catheter ablation in patients with atrial fibrillation (AF). However, outcomes of cryoballoon ablation (CBA) in patients with renal insufficiency are not fully elucidated. This study aimed to compare outcomes of CBA in AF patients with chronic kidney disease (CKD) versus those without CKD and to assess changes in renal function over 12 months following CBA. Methods: A total of 839 patients (65.1% with non-paroxysmal AF [PAF]) who underwent de novo CBA were prospectively enrolled. We divided patients into two groups based on creatinine clearance rate (CCr) and performed intracardiac echocardiography (ICE)-guided contrast agent-free CBA. Results: In comparison with patients without CKD (CCr >50, n=722), those with CKD (CCr ≤50, n=117) were older and predominantly female, had a lower body mass index, and showed a higher prevalence of heart failure and hypertension. Mean CHA₂DS₂-VAS score was significantly higher in CKD group than in non-CKD group. Procedure-related complications were not significantly different between two groups. During a mean follow-up period of 25.4±11.9 months, clinical recurrence occurred in 182 patients (21.7%) and not significantly different between two groups. In multivariate analysis, non-PAF and left atrial size were independent predictors of AF recurrence. CCr levels significantly improved over 12 months after CBA in CKD group. Conclusions: ICE-guided contrast-agent-free CBA showed comparable long-term clinical outcomes without increasing procedure-related complications and improvement of renal function over 12 months following CBA in AF patients with CKD.

• Archives of Pharmacal Research
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• 제13권1호
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• pp.43-50
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• 1990

Conformational free energy calculations using an empirical potential function (ECEPP/2) and hydration shell model were carried out on the four-4-aminodiphenyl sulfone analogues of 4, 4'-diamino-2' methyldiphenyl sulfone, 4, 2', 4-triaminodiphenyl sulfone, 4, 4'-diaminodiphenyl sulfone, and 4-aminodiphenyl sulfone as antibacterial agents on Mycobacterium lufu. The conformational energy was minimized from starting conformations which included possible combinations of torsion angles in the molecule. The conformational entropy change of each conformation was computed using a harmonic approximation. To understand the hydration effect on the conformation of the molecule in aqueous solution, the contributions of water-accessible volume and the hydration free energy of each group or atom in the lowest-free-energy conformation was calculated and compared each other. From comparison of the computed lowest-free-energy conformations of four analogues with their antibacterial activities, it is known that the conformation and the hydrophobicity of sulfonyl group and its adjacent carbon atom in each compound are the essential factors to show the strong antibacterial activity.

• 한국정보과학회논문지:소프트웨어및응용
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• 제28권10호
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• pp.732-742
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• 2001

컴퓨터 분야에서 에이전트의 개념의 전자 상거래, 정보 검색과 같은 많은 어플리케이션에 응용되어 중요시되고 있지만, 소프트웨어 테스트 분야에 에이전트의 개념이 적용되는 것은 드문 일이었다. 테스트 에이전트 시트템 (TAS)은 에이전트 개념을 소프트웨어 테스트 분야에 적용한 새로운 도구로, 'User Interface Agent', 'Test Case Selection & Testing Agent'그리고'Regression Test Agent'로 구성되어 있다. 이들 세개의 에이전트들은 각각 지능성을 나타내는 규칙들을 가지고 객체 지향 프로세스를 딸라 자율적으로 테스트를 진행한다. 이 시스템은 두 가지 측면에서 장점을 가지고 있다. 첫째는 자율적으로 테스트 진행시켜 테스터의 간섭을 최소화한다는 것이고 둘째는 지능적으로 중복이 없고 일관성이 있는 효율적인 테스트케이스를 선택하여 테스트 시간을 감소시키면서 오류검출능력은 향상된다는 것이다. 본 논문에서는 사례를 중심으로 실행과정을 기술하여 TAS를 구성하는 세 개의 에이전트들의 자율적인 행동으로 테스트가 진행되는 것을 보여 TAS가 테스트의 간섭을 최소화한다는 것을 보인다. 그리고 4가지유형의 실험을 수행하여 테스트 시간의 단축과 오류 검출 효과향상을 기술한다.

• Korean Chemical Engineering Research
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• 제48권4호
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• pp.413-416
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• 2010

본 연구에서는 연근의 추출물에서 기능성화장품 소재를 개발하고자 하였다. 용매는 70~100%의 에탄올을 이용하였으며, 연근의 유효성분으로 nuciferine을 확인하였다. 연근 추출물의 화장품소재로서의 응용가능성을 보기 위해 안전성시험(MTT assay), 주름개선 효과시험(Elastase 활성저해 시험) 및 항산화효과시험(DPPH free radical scavenging assay)을 실시하였다. 100% 에탄올로 연근을 추출할 경우 $100{\mu}g/ml$의 농도에서 세포생존율이 80% 이상이어서 연근 추출물은 화장품소재로서 비교적 안전함을 알 수 있었다. 또한 연근 추출물은 $100{\mu}g/ml$의 농도에서 elastase 활성억제가 40~50%를 보여주어서 비교적 우수한 주름개선 효과를 나타내었다. 50% 항산화 저해능을 보이는 농도($FSC_{50}$)는 $5.0{\sim}38{\mu}g/ml$로 연근 추출물의 항산화효과가 매우 우수하였다. 따라서 연근 에탄올추출물은 주름개선 기능성화장품 소재로서 그 가능성이 높음을 알 수 있었다.

• Fibers and Polymers
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• 제4권4호
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• pp.182-187
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• 2003

Low molecular weight copolymers of maleic anhydride and vinyl acetate were prepared to develop formaldehyde free cross-linking agents. Since lower molecular weight is favorable for efficient penetration of the finishing agent into the cotton fibers in the padding process, the concentration of the initiator, chain transfer agent and the monomer ratios were varied to obtain copolymers of low molecular weights. The prepared polymers were characterized by GPC, $^1{H-NMR}$, FTIR, DSC and TGA. Copolymers of molecular weights of 2 000 to 10 000 were obtained and it was found that the most efficient method of controlling the molecular weight was by varying the monomer ratios. Poly(maleic anhydride-co-vinyl acetate) did not dissolve in water, but the maleic anhydride residue hydrolyzed within a few minutes to form poly(maleic acid-co-vinyl acetate) and dissolved in water. However, the maleic acid units undergo dehydration to form anhydride groups on heating above ${160}^{\circ}C$ to some extent even in the absence of catalysts. The possibility of using the copolymers as durable press finishing agent for cotton fabric was investigated. Lower molecular weight poly(maleic anhydride-co-vinyl acetate) copolymers were more efficient in introducing crease resistance, which appears to be due to the more efficient penetration of the cross-linking agent into cotton fabrics. The wrinkle recovery angles of cotton fabrics treated with poly(maleic anhydride-co-vinyl acetate) copolymers were slightly lower than those treated with DMDHEU and were higher when higher curing temperatures or higher concentrations of copolymer were used, and when catalyst, $NaH_2$$PO_2$, was added. The strength retention of the poly(maleic anhydride-co-vinyl acetate) treated cotton fabrics was excellent.

• Bulletin of the Korean Chemical Society
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• 제25권1호
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• pp.23-24
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• 2004

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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• pp.85-88
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• 2008

As super-high-strength concrete uses a large amount of binder, there is an autogenous shrinkage strain larger than dry shrinkage and it degrades the quality of structures. Thus, we need a technology to minimize the shrinkage strain of super-high-strength concrete. Accordingly, the present study prepared super-high-strength concrete with design strength of over 100MPa and, using an embedded gauge, measured the shrinkage strain of free shrinkage specimens for super-high-strength concrete containing expansion agent. According to the results of this study, the expansion rate of concrete increased in the early stage due to the admixture of expansion agent, but the shrinkage rate went down with the lapse of time. The effect of the admixture of expansion agent on compressive strength appeared insignificant. Further research shall be made on different kinds of expansion agents and various mixture ratios for basic analysis to reduce autogenous shrinkage of super-high-strength concrete.

• Elastomers and Composites
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• 제55권2호
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• pp.95-102
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• 2020

Currently, peroxide cure is a widely used cure system for rubber materials. To improve its effectivity, co-agents are used to enhance the peroxide efficiency and mechanical properties of rubber materials. Co-agents are multifunctional organic compounds that are highly reactive towards free radicals. These co-agents provide higher cross-link densities for a given peroxide concentration and improve the mechanical properties of peroxide-cured rubber composites. In this study, trimethylolpropane trimethacrylate (TMPTMA) and high vinyl 1,2-polybutadiene (HVPBD) were used as co-agents. In order to obtain a concentration that achieves a favorable balance between mechanical properties and co-agent concentration, this research investigated the effects of co-agent content on the curing characteristics, chemical structures, and mechanical properties of HNBR composites. Additionally, the heat aging properties and compression sets of HNBR composites were investigated. Based on the results, we found that the HNBR composites with TMPTMA co-agents exhibited higher Shore A hardness and 10% modulus and better heat aging resistance and compression set than that of the HVPBD co-agent. The heat aging resistance and compression set deteriorated with increasing HVPBD content.

• 대한산업공학회지
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• 제39권6호
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• pp.562-576
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• 2013

Power TAC (Power Trading Agent Competition) is an agent-based simulation for competitions between electricity brokering agents on the smart grid. To win the competition, agents obtain electricity from the electricity wholesale market among the power plants. In this operation, a key to success is balancing the demand of the customer and the supply from the plants because any imbalance results in a significant penalty to the brokering agent. Given the bidding on the wholesale market requires the price and the quantity on the electricity, this paper proposes four different price estimation strategies: exponentially moving average, linear regression, fuzzy logic, and support vector regression. Our evaluations with the competition simulation show which strategy is better than which, and which strategy wins in the free-for-all situations. This result is a crucial component in designing an electricity brokering agent in both Power TAC and the real world.

• Archives of Pharmacal Research
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• 제19권2호
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• pp.132-136
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• 1996

Exogenously applied oxygen free radical generating agent, pyrogallol, highly elevated extracellular glutamate accumulation and augmented N-methyl-D-aspartate (NMDA)-induced glutamate accumulation in cerebellar granule neuronal cells, but did not in astrocytes. Superoxide dismutase remarkably decreased the pyrogallol-induced glutamate accumulation, but either NMDA or kainate antagonists did not. In addition, pyrogallol did not affect the NMDAinduced intracellular calcium elevation. Pyrogallol partially blocked glutamate uptake into astrocytes. These results suggest that oxygen free radicals elevate extracellular glutamate accumulation by stimulating the release of glutamate as well as blocking the glutamate uptake.