• 대한기계학회논문집A
• /
• 제32권4호
• /
• pp.347-353
• /
• 2008

Reflected light can be decomposed into specular and diffuse components according to the light reflectance theory and experiments. The specular component appears in smooth surfaces mainly, while the diffuse one is visible in rough surfaces mostly. Therefore, each component can be used in forming their correlations to a surface roughness. However, they cannot represent the whole surface roughness seamlessly, because each formulation is merely validated in their available surface roughness regions. To solve this problem, new approaches to properly blend two light components in all regions are proposed in this paper. First is the weighting function method that a blending zone and rate can be flexibly adjusted, and second is the neural network method based on the learning from the measurement data. Simulations based on the light reflectance theory were conducted to examine its performance, and then experiments conducted to prove the enhancement of the measurement accuracy and reliability through the whole surface roughness regions.

• 대한토목학회논문집
• /
• 제11권1호
• /
• pp.17-27
• /
• 1991

본 논문에서는 구조물의 응력확대 계수를 균열선단주위에서 정의되는 표면적분법에 의하여 구하는 방법을 연구하였다. 통상의 J적분법을 변형시켜 표면 적분법을 유도하였으며 물체력을 고려하는 경우도 포함시켰다. 유한요소 해석결과를 입력변수로 받아들여 표면적분법으로 응력확대계수 $K_I$과 $K_{II}$를 구하는 프로그램을 작성하였다. 형상비(요소길이/균열길이)가 25% 정도인 요소망에서 본 논문에서 제안한 포물선형태의 평활곡선함수를 사용한 결과, 외측적분반경이 균열길이의 1/3~1 되는 구간에서 비교적 정확한 응력확대 계수가 얻어지는 것을 알수 있었다.

• 한국주거학회논문집
• /
• 제25권6호
• /
• pp.75-84
• /
• 2014

The purpose of this study was to identify a direction for increase of resident participation by analyzing the social relations of resident participation. In the research method, the method of statistical analysis was added to the legal institutional method. As a result, the following findings were obtained: First, it is very important that the resident representative meeting at the center of the participation of the resident organization should take the role in and responsibility for the promotion of participation. Second, it is necessary to have smooth communication with voluntary groups such as women's association or club forming the coordinating group. Third, Among other things, it is judged that residents should have an active will to participate and practice in order to promote their participation in the apartment community. The above results imply that participation should be promoted by enabling residents to perform four functions of resident participation. Accordingly, the promotion of participation based on the function of participation is very necessary and important.

• 한국학교수학회논문집
• /
• 제6권2호
• /
• pp.21-37
• /
• 2003

본 논문은 학교수학의 연계성에 대하여 체계적으로 비교하고 분석하였다. 또한 수학적 의미에 바탕을 둔 수평적 및 수직적 연계성을 분류하고 검토함으로써 학교수학에 관한 이론적 기반을 조성하고자 하였다. 지금까지 학교수학은 일반적으로 수직적 연계성에 중심을 두어 거시적인 차원에서 수학을 바라보았으나 본 논문은 수평적 연계성을 살펴봄으로써 미시적인 측면과 거시적인 측면을 함께 살펴보았다. 또한 인터넷을 활용함으로써 다양한 활동을 제공하고 특히 함수에 관한 교육과정의 변화를 모색한다. 그리하여 우리는 함수의 지도를 원활하게 할 수 있는 활동과 모델을 제시한다.

• 한국발생생물학회지:발생과생식
• /
• 제20권1호
• /
• pp.11-22
• /
• 2016

The ultrastructures of germ cells and the functions of Leydig cells and Sertoli cells during spermatogenesis in male Kareius bicoloratus (Pleuronectidae) were investigated by electron microscope observation. Each of the well-developed Leydig cells during active maturation division and before spermiation contained an ovoid vesicular nucleus, a number of smooth endoplasmic reticula, well-developed tubular or vesicular mitochondrial cristae, and several lipid droplets in the cytoplasm. It is assumed that Leydig cells are typical steroidogenic cells showing cytological characteristics associated with male steroidogenesis. No cyclic structural changes in the Leydig cells were observed through the year. However, although no clear evidence of steroidogenesis or of any transfer of nutrients from the Sertoli cells to spermatogenic cells was observed, cyclic structural changes in the Sertoli cells were observed over the year. During the period of undischarged germ cell degeneration after spermiation, the Sertoli cells evidenced a lysosomal system associated with phagocytic function in the seminiferous lobules. In this study, the Sertoli cells function in phagocytosis and the resorption of products originating from degenerating spermatids and spermatozoa after spermiation. The spermatozoon lacks an acrosome, as have been shown in all teleost fish spermatozoa. The flagellum or sperm tail of this species evidences the typical 9+2 array of microtubules.

• Biomolecules & Therapeutics
• /
• 제16권3호
• /
• pp.249-254
• /
• 2008

The present study was undertaken to determine whether hypoxia influences on the agonist-induced vascular smooth muscle contraction and, if so, to investigate the related mechanism. The measurement of isometric contractions using a computerized data acquisition system was combined with molecular experiments. Hypoxia significantly inhibited fluoride-induced contraction regardless of endothelial function, but there was no relaxation on thromboxane $A_2$ mimetic U-46619-induced contraction suggesting that other pathway such as $Ca^{2+}$ entry or thin filament regulation was not affected. In addition, hypoxia significantly decreased fluoride-induced increase of phospho-myosin-targeting subunit of myosin light chain phosphatase (pMYPT1). Interestingly, hypoxia didn't inhibit significantly phenylephrine-induced contraction suggesting that myosin light chain kinase (MLCK) activity or thin filament regulation is less important on the hypoxia-induced vasorelaxation in the denuded muscle than Rho-kinase activity. In conclusion, this study provides the evidence and possible related mechanism concerning the vasodilation effect of hypoxia on the agonist-specific contraction in rat aortic rings regardless of endothelial function.

• International Journal of Automotive Technology
• /
• 제8권3호
• /
• pp.383-394
• /
• 2007

Due to the clutch's non-linear dynamics, time-delays, external disturbance and parameter uncertainty, the automated clutch is difficult to control precisely during the launch process or automatic mechanical transmission (AMT) vehicles. In this paper, an enhanced fuzzy sliding mode controller (EFSMC) is proposed to control the automated clutch. The sliding and global stability conditions are formulated and analyzed in terms of the Lyapunov full quadratic form. The chattering phenomenon is handled by using a saturation function to replace the pure sign function and fuzzy logic adaptation system in the control law. To meet the real-time requirement of the automated clutch, the region-wise linear technology s adopted to reduce the fuzzy rules of the EFSMC. The simulation results have shown hat the proposed controller can achieve a higher performance with minimum reaching time and smooth control actions. In addition, our data also show that the controller is effective and robust to the parametric variation and external disturbance.

• International Journal of Aeronautical and Space Sciences
• /
• 제3권2호
• /
• pp.46-58
• /
• 2002

An inverse method is introduced to construct benchmark problems for the numerical solution of initial value problems. Benchmark problems constructed through this method have a known exact solution, even though analytical solutions are generally not obtainable. The solution is constructed such that it lies near a given approximate numerical solution, and therefore the special case solution can be generated in a versatile and physically meaningful fashion and can serve as a benchmark problem to validate approximate solution methods. A smooth interpolation of the approximate solution is forced to exactly satisfy the differential equation by analytically deriving a small forcing function to absorb all of the errors in the interpolated approximate solution. A multi-variable orthogonal function expansion method and computer symbol manipulation are successfully used for this process. Using this special case exact solution, it is possible to directly investigate the relationship between global errors of a candidate numerical solution process and the associated tuning parameters for a given code and a given problem. Under the assumption that the original differential equation is well-posed with respect to the small perturbations, we thereby obtain valuable information about the optimal choice of the tuning parameters and the achievable accuracy of the numerical solution. Illustrative examples show the utility of this method not only for the ordinary differential equations (ODEs) but for the partial differential equations (PDEs).

• 대한수학회지
• /
• 제49권3호
• /
• pp.585-604
• /
• 2012

In this paper we consider the evolution of the rolling stone with a rotationally symmetric nonconvex compact initial surface ${\Sigma}_0$ under the Gauss curvature flow. Let $X:S^n{\times}[0,\;{\infty}){\rightarrow}\mathbb{R}^{n+1}$ be the embeddings of the sphere in $\mathbb{R}^{n+1}$ such that $\Sigma(t)=X(S^n,t)$ is the surface at time t and ${\Sigma}(0)={\Sigma}_0$. As a consequence the parabolic equation describing the motion of the hypersurface becomes degenerate on the interface separating the nonconvex part from the strictly convex side, since one of the curvature will be zero on the interface. By expressing the strictly convex part of the surface near the interface as a graph of a function $z=f(r,t)$ and the non-convex part of the surface near the interface as a graph of a function $z={\varphi}(r)$, we show that if at time $t=0$, $g=\frac{1}{n}f^{n-1}_{r}$ vanishes linearly at the interface, the $g(r,t)$ will become smooth up to the interface for long time before focusing.

• 대한수학회보
• /
• 제45권4호
• /
• pp.663-670
• /
• 2008

In this paper, the aim is to solve the neutral delay differential equations in the following form using multiquadric approximation scheme, (1) $$\{_{\;y(t)\;=\;{\phi}(t),\;\;\;\;\;t\;{\leq}\;{t_1},}^{\;y'(t)\;=\;f(t,\;y(t),\;y(t\;-\;{\tau}(t,\;y(t))),\;y'(t\;-\;{\sigma}(t,\;y(t)))),\;{t_1}\;{\leq}\;t\;{\leq}\;{t_f},}$$ where f : $[t_1,\;t_f]\;{\times}\;R\;{\times}\;R\;{\times}\;R\;{\rightarrow}\;R$ is a smooth function, $\tau(t,\;y(t))$ and $\sigma(t,\;y(t))$ are continuous functions on $[t_1,\;t_f]{\times}R$ such that t-$\tau(t,\;y(t))$ < $t_f$ and t - $\sigma(t,\;y(t))$ < $t_f$. Also $\phi(t)$ represents the initial function or the initial data. Hence, we present the advantage of using the multiquadric approximation scheme. In the sequel, presented numerical solutions of some experiments, illustrate the high accuracy and the efficiency of the proposed method even where the data points are scattered.