• Corrosion Science and Technology
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• 제4권1호
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• pp.8-14
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• 2005

The corrosion behaviour of mild steel in phosphoric acid solution in the presence and absence of pollutants viz. Chloride, Fluoride and Sulfate ions at 302K-333K was studied using mass loss and potentiostatic polarization methods. The addition of chloride and sulfate ions inhibits the mild steel corrosion in phosphoric acid while fluoride ions stimulate it. The effect of temperature on the corrosion behaviour of mild steel indicated that inhibition of chloride and sulfate ions decreased with increasing temperature. The adsorption of these ions (Chloride and sulfate) on the mild steel surface in acid has been found to obey Langmuir adsorption isotherm. The values of activation energy (Ea) and free energy of adsorption ($\Delta$) indicated physical adsorption of these ions (chloride and sulfate) on the mild steel surface. The plot of $logW_{f}$ against time (days) at 302K gives a straight line, which suggested that it obeys first order kinetics and also calculate the rate constant k and half-life time $t_{1/2}$.

• 한국방재학회 논문집
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• 제8권1호
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• pp.133-138
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• 2008

외해에서 내습하는 파랑 자료를 분석하는 일은 연안에서 발생하는 문제를 해결함에 있어 기본이 되기 때문에 매우 중요하다. 파랑을 해석하는 방법에는 크게 수치 모델을 이용하는 방법과 해석 해를 이용하는 방법이 있다. 수치 모델의 경우, 다양한 지형과 파랑 조건에 대해 적용할 수 있다는 장점이 있지만 수치 오차를 고려해야 하는 번거로움이 있다. 반면, 해석 해의 경우 수치 오차 없이 빠르고 정확하게 해를 구할 수 있다는 장점이 있지만 특정한 지형 및 파랑 조건에서만 성립한다는 단점이 있다. 본 연구에서는 수치적인 기법과 해석적인 접근을 혼합하여 수치 오차를 최소화시키면서 다양한 조건에 적용이 가능한 완경사 방정식의 해를 유도하였다. 유도된 해를 기존의 수치 해와 비교한 결과 매우 잘 일치한다는 알 수 있었다.

• 대한약침학회지
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• 제23권4호
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• pp.220-229
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• 2020

Objectives: Although Acne vulgaris is a chronic skin disease, which its standard treatment causes therapeutic limitations and some common adverse effects, medicinal plants can be effective in treatment with low adverse effects as combination therapy. Myrtle (Myrtus Communis) has some beneficial properties, which has been administered topically and orally for some skin diseases in Persian medicine. This study aimed to compare the efficacy and safety of Myrtle formula and 1% clindamycin topical solution. Methods: This was a split-face clinical trial that was done on 55 patients with mild to moderate acne vulgaris for 16 weeks. The patients received topical Myrtle solution to the right side of the face (group 1) and clindamycin solution to the left side (group 2) twice daily for 12 weeks. All participants were examined for the acne severity index (ASI) and total acne lesions counting (TLC) at certain times during the study. Then, they stopped using them for four weeks. They also did not take the drug in the final four weeks of the study. Results: Forty-eight patients completed the study for 16 weeks; 40 (83.2%) patients were female and the rest of them were male. The mean age and standard deviation were 25.62 ± 7.62 years. After 12 weeks, the percentage changes of comedones, inflammatory lesions, ASI and TLC were significantly reduced in both groups (p < 0.001). The percentage change of inflammatory lesions and ASI decrease was significantly higher in the group 1 (p = 0.03). There was no significant difference in the incidence of side effects between the two groups. There was a more significant decrease in sebum percentage change in the group 1 (p = 0.003). Conclusion: Myrtle lotion was effective and safe for the treatment of mild to moderate acne vulgaris.

• 대한수학회지
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• 제51권6호
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• pp.1123-1139
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• 2014

In this work, we investigate the existence of the extremal solutions for a class of fractional partial differential equations with order 1 < ${\alpha}$ < 2 by upper and lower solution method. Using the theory of Hausdorff measure of noncompactness, a series of results about the solutions to such differential equations is obtained.

• 한국해안·해양공학회논문집
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• 제21권2호
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• pp.117-126
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• 2009

억류파를 제외한 수정 완경사파랑식과 고유함수 전개법의 평면파 근사식에 대한 정밀도를 검토하기 위해 다수의 수치실험 결과를 제시하였다. 본 연구에서 두 해석해가 사용되었으며 하나는 수정 완경사파랑식에 대한 Porter(2003)의 해이고 다른 하나는 평면파 근사식에 산란체법을 적용한 서(2008a)의 해이다. 급변 지형에서의 파랑변형에 대한 기존 결과와의 직접 비교를 통해 평면파 근사식 모형이 수정 완경사파랑식 보다 잘 기술하는 것으로 나타났다.

• 충청수학회지
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• 제28권3호
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• pp.365-375
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• 2015

Of concern is the existence, uniqueness, and continuous dependence of a mild solution of a nonlocal Cauchy problem for a semilinear mixed Volterra-Fredholm functional integrodifferential equation. Our analysis is based on the theory of a strongly continuous semigroup of operators and the Banach fixed point theorem.

• 충청수학회지
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• 제27권1호
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• pp.89-97
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• 2014

We study the existence of mild solutions for neutral differential equations with nonlocal conditions in the ${\alpha}$-norm.

• 대한수학회지
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• 제39권5호
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• pp.775-782
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• 2002

In this paper we prove the existence of mild soultions for semilinear differential equations in a Banach space. The results are obtained by using the semigroup theory and the Schaefer fixed point theorem. An example is provided to illustrate the theory.

• Journal of applied mathematics & informatics
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• 제33권1_2호
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• pp.45-60
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• 2015

This paper is concerned with the existence of mild solutions for partial neutral functional integrodifferential equations with infinite delay in Banach spaces. The results are obtained by using resolvent operators and Krasnoselski-Schaefer type fixed point theorem. An example is provided to illustrate the results.

• 충청수학회지
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• 제29권1호
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• pp.49-58
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• 2016

We study the existence of S-asymptotically ${\omega}$-periodic mild solutions of partial functional integrodifferential equation by the method of Caicedo et al. [2].