• Corrosion Science and Technology
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• v.4 no.6
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• pp.231-235
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• 2005

The inhibitive effect of extracts of tamarind seeds and jackfruit seeds, curry leaves and henna leaves on corrosion of mild steel in 1M HCl solution have been studied by weight loss, potentiodynamic polarization and impedance measurements. Results obtained from the electrochemical techniques were in good agreement with weight loss results. From the weight loss data, the values of surface coverage ($\Theta$) and corrosion rate were calculated. The inhibition efficiency (IE) increased with increasing inhibitor concentration in 1M HCl solution. In all the cases the adsorption of the natural product extracts on the mild steel surface from 1M HCl follows the Langmuir adsorption isotherm relationship. Potentiodynamic polarization studies reveal the fact that all the four natural product extracts act as mixed type inhibitors. The decrease in the inhibition efficiency follows the order: Extracts of jackfruit seed>henna leaves>curry leaves>tamarind seed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.65-66
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• 2002

One aspect of the stiction problem may be explained by the action of capillary forces in conjunction with surface elasticity. In the present work, the interaction between two elastic half-spaces separated by a small liquid bridge is investigated. By minimizing the total free energy stored in the interface (including elastic energy and surface energy), the equilibrium interface geometry is determined analytically in the case where there is no solid-solid contact. A non-dimensional number, $N_c=299\frac{{\gamma}^2_{LA}cos^2{\theta}V_o}{E^{'2}H^5}$ is found to govern the structure stability. When $N_c{\ge}1$, the two surfaces jump into solid-solid contact and, once this occurs, the contact area will continue to expand until the two surfaces are in full contact.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2008.04a
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• pp.37-39
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• 2008

The purpose of this study is to improve the defects of DPP fabric by heat setting and to describe the change of physical properties of DPP fabrics. The thermosetting was carried out in autoclave from 100 to 140$^{\circ}C$ temperature range for 10min.. In this study, we investigated the effect of the thermosetting temperatures on the structural, thermal, mechanical properties and dyeability of DPP fabrics. The melting peak of multi peak changed to single peak with an increased thermosetting temperatures. The melting energy(J/g), the tensile strength and elongation were found to increase with increasing temperature of heat setting. The diffraction peak at Bragg angle(2${\theta}$) about 13.8$^{\circ}$ were very strong, and diffraction intensity, d-spacing and half-width decreased with increasing thermosetting temperatures. On the other hand, the dyeability(K/S) and crease recovery decreased with an increasing thermosetting temperatures.

• Journal of the Korean Mathematical Society
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• v.47 no.3
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• pp.585-598
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• 2010

We deal with Matveev complexity of compact orientable 3-manifolds represented via Heegaard diagrams. This lead us to the definition of modified Heegaard complexity of Heegaard diagrams and of manifolds. We define a class of manifolds which are generalizations of Dunwoody manifolds, including cyclic branched coverings of two-bridge knots and links, torus knots, some pretzel knots, and some theta-graphs. Using modified Heegaard complexity, we obtain upper bounds for their Matveev complexity, which linearly depend on the order of the covering. Moreover, using homology arguments due to Matveev and Pervova we obtain lower bounds.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.985-987
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• 2005

자료의 크기가 방대한 응용 프로그램에서는 메인 메모리와 저장 장치간의 자료 입출력(I/O)이 전체 계산의 주요 병목 요인으로 작용한다. 본 논문은 [2004 한국정보처리학회 추계논문집 제11권 제2호 1139-1142]에서 제안된 그리드(grid) 그래프를 위한 입출력 효율적인 depth-first search (DFS) 알고리즘을 지원하기 위한 입출력 효율적인 영역 구분자를 구하는 알고리즘을 제안 한다. 그 입출력 복잡도 (I/O-Complexity)는 O(Soft(N))이다. 여기서 N=|V|+|E|이고 $sort(N)=\Theta((N/B)log_{M/B}(N/B))$이다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.01a
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• pp.111-112
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• 2013

본 논문에서는 자이로 센서(Gyro Senor)와 가속도 센서(Accelerometer)를 이용하여 가속도(x")와 각 축의 각속도(${\theta}^{\prime}$)를 계산하여, 쿼드콥터와의 결합을 통해 자세를 스스로 제어하는 방법을 제안한다. 현재 나온 국내 외 쿼드콥터 기능의 현황과 그 제품들의 회로, 그리고 자이로센서와 가속도센서에 관한 논문들을 분석하여 자이로센서와 가속도센서를 통해 쿼드콥터의 성능을 향상시키는 방안을 제시하였다. 그 결과 센서결합을 통해 공중에서 비스듬하게 잡고있는 상황 등 기울어진 상태에서 스스로 자세를 제어하는 기능이 구현되었음을 확인할 수 있었다.

• Communications of the Korean Mathematical Society
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• v.27 no.4
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• pp.809-813
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• 2012

We introduce the notion of R($g$, $g^{\prime}$)-continuity on generalized topological spaces, which is a strong form of ($g$, $g^{\prime}$)-continuity. We investigate some properties and relationships among R($g$, $g^{\prime}$)-continuity, ($g$, $g^{\prime}$)-continuity and some strong forms of ($g$, $g^{\prime}$)-continuity.

• Journal of applied mathematics & informatics
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• v.32 no.1_2
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• pp.211-225
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• 2014

A new class of smoothing functions is introduced in this paper, which includes some important smoothing complementarity functions as its special cases. Based on this new smoothing function, we proposed a smoothing Newton method. Our algorithm needs only to solve one linear system of equations. Without requiring the nonemptyness and boundedness of the solution set, the proposed algorithm is proved to be globally convergent. Numerical results indicate that the smoothing Newton method based on the new proposed class of smoothing functions with ${\theta}{\in}(0,1)$ seems to have better numerical performance than those based on some other important smoothing functions, which also demonstrate that our algorithm is promising.

• Honam Mathematical Journal
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• v.35 no.3
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• pp.351-372
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• 2013

In this paper, we study a distinction the two generating functions : ${\varphi}^k(q)=\sum_{n=0}^{\infty}r_k(n)q^n$ and ${\varphi}^{*,k}(q)={\varphi}^k(q)-{\varphi}^k(q^2)$ ($k$ = 2, 4, 6, 8, 10, 12, 16), where $r_k(n)$ is the number of representations of $n$ as the sum of $k$ squares. We also obtain some congruences of representation numbers and divisor function.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.222-227
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• 2008

Complex terrain like hill, mountain, and escarpment etc. makes complex air flow. This topographic condition will affect not only speed but also turbulence of wind over the complex terrain. In this paper, turbulence intensities are considered to investigate characteristics of wind over cone-type hills. There are five simple hill models with different slope 0.1${\sim}$0.5(tan${\theta}$) for wind tunnel test. It was observed through wind tunnel tests that turbulence intensities of down-slope wind at the end of the 3-Dimensional hills remarkably increased but ones of windward slope wind at the front side of the hills slightly increased. Also, turbulence intensities proportionally increased with slope of the cone-type hills.