• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.326-326
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• 2001

Epoxy/glass fiber 복합재는 높은 strength와 stiffness를 갖는 장점이 있지만 impact strained energy를 효율적으로 발산시킬 수 있는 mechanism을 가지고 있지 않기 때문에 damping 능력이 떨어진다 Impact strength와 damping 성능을 증가시키기 위해 사용되어지고 있는 방법은 형상기억 고분자를 이용한 것으로 상대적으로 높은 strength와 impact에 대한 흡수 및 발산을 가지고 있다 형상기억 고분자는 glass transition temperature(G$_{g}$) 근처에서 높은 damping 능력을 가지고 있다. (중략)

• Wind and Structures
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• v.16 no.3
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• pp.241-248
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• 2013

The wind turbine blade is a very important part of the rotor. Extraction of energy from wind depends on the design of blade. In this work, the analysis is done on a blade of length 38.95 m which is designed for V82-1.65 MW horizontal axis wind turbine (supplied by Vestas). The airfoil taken for the blade is NACA 634-221 which is same from root to tip. The analysis of designed blade is done in flap-wise loading. Two shapes of the spar are taken, one of them is of square shape and the other one is combination of square and cross shape. The blade and spar are of the same composite material. The Finite element analysis of designed blade is done in ANSYS. This work is focused on the two segments of blade, root segment and transition segment. Result obtained from ANSYS is compared with the experimental work.

• Proceedings of the KOSOMBE Conference
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• v.1989 no.05
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• pp.9-12
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• 1989

A preliminary study has been conducted to demonstrate the effect of laser heat treatment on Ni Ti alloy dental arch wires ($0.016"\;{\times}\;0.022"$ and $0.018"\;{\times}\;0.026"$, rectangular shape). Changes in mechanical and thermal properties and surface morphologies are investigated by using optical and scanning electron microscope (SEM), energy dispersive x-ray microprobe analysis(EDX), differential scanning calorimeter (DSC), and micro hardness tester. The results indicate that the laser can affect the thermal equilibrium state of the localized surface. Titanium rich surface film is formed by the laser treatment. The surface film and rapidly resolidified underlying structures show better chemical resistance than the matrix material. Phase transition temperatures which are related to shape recovery temperatures are changed after laser treatment. Hardness of resolidified area and heat affected zone are lower than before treatment.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.4
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• pp.174-182
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• 2003

Recently, medical imaging has taken interest on CAD based solution for anatomical part fabrication or finite element analysis of human body. In principle, contours representing object boundary are obtained through image processing techniques. Surface models are then approximated by a skinning method. For this, various methods should be applied to medical images and contours. The major bottleneck of the reconstruction is to remove shape inconsistency between contours and to generate the branching surface. In order to solve these problems, bi-directional smoothing and the composite contour generation method are proposed. Bi-directional smoothing has advantage of removing the shape inconsistency between contours and minimizing shrinkage effect with a large number of iterations. The composite contour by the proposed method ensures smooth transition in branching region.

• Korean Institute of Interior Design Journal
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• v.15 no.6 s.59
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• pp.52-59
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• 2006

The study is intended to clarify the ideologies and principles applied to the formative expression of church architecture which is contained both the God and human. Iconography as the relation between described target and the meaning as meaning analysis especially emphasized since the religious reason in religious art. Iconography is the area of discussing rules and habits and involved in the pieces of transition from the piece of experience obtained by sensing to the one of the ethical structure. N. L. Prak who apply meaning theory of E. Panofsky who distinguish between iconography and iconology clear relation of mental foundation which characteristics of shape of art and its concretion in architecture categorized the shape of meaning in three steps. Among them, conscious symbol and unconscious symbol correspond to iconography and iconology of Panofsky respectively. The symbol is mainly showed in religious architecture and is not related to simple practical architecture. Such symbol system can be important discussion objects in modern church architecture and necessary expressional system for expressional characteristics.

• Journal of Ocean Engineering and Technology
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• v.11 no.3
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• pp.29-38
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• 1997

Crack penetration behavior by fatigue crack propagation and measurements of AE before-and-after crack penetration were examined using SS41 steel plate. Experimental crack shape of SU type was in good agreement with calculated shape rather than S type. Crack propagation behavior on the front surface appears not to change markedly after penetration. However, crack growth on the back surface appears to accelerate as reported by author. As a crack propagates, AE occurred heavily just before penetration. Then, it decreases and crack is penetrating. A transition from plane strain to plane stress was observed by fractographic study. At this time, separation of fracture surface was shown which affects AE occurrence.

• Communications for Statistical Applications and Methods
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• v.29 no.6
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• pp.695-708
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• 2022

Recently, several studies have been conducted using state space model. In this study, a dynamic linear model with state space model form is applied to stock data. The monthly returns for 135 Korean stocks are fitted to a dynamic linear model, to obtain an estimate of the time-varying 𝛽-coefficient time-series. The model formula used for the return is a capital asset pricing model formula explained in economics. In particular, the transition equation of the state space model form is appropriately modified to satisfy the assumptions of the error term. k-shape clustering is performed to classify the 135 estimated 𝛽 time-series into several groups. As a result of the clustering, four clusters are obtained, each consisting of approximately 30 stocks. It is found that the distribution is different for each group, so that it is well grouped to have its own characteristics. In addition, a common pattern is observed for each group, which could be interpreted appropriately.

• Journal of the Korean Society of Visualization
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• v.22 no.1
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• pp.61-67
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• 2024

In this study, the behavior of water droplets on a solid-infused surface was evaluated by quantifying a water droplet's contact angle, sliding angle, and terminal velocity. The contact angle hysteresis and sliding angle of water on the solid-infused surface were measured to be lower than those of the hydrophobic PTFE surface. It led to the enhancement of the initiation of the water droplet's movement. When the capillary number was lower than Ca < 0.004, the terminal velocity of the water droplet on the solid-infused surface was higher than the PTFE surface due to the low contact line resistance. However, the transition of the droplet morphology from a hemispherical shape to a streamlined teardrop shape beyond Ca > 0.004 lost the effect of reducing frictional resistance on the solid-infused surface.

• Journal of the Korean Magnetic Resonance Society
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• v.11 no.2
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• pp.64-72
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• 2007

[ $^1H$ ] nuclear magnetic resonance (NMR) experiments have been performed at 30 - 300 K and 7 T to investigate dynamics of hydrogen bond network in the single crystal $(NH_4)_3H(SO_4)_2$. The two proton sites, ammonium proton and hydrogen-bond proton, are identified from the $^1H$ NMR MAS spectrum at 340 K. As temperature decreases, the $^1H$ NMR spectrum shifts to the higher frequency side with a larger linewidth. The spectrum at 65 K shows a distinctive change in line shape toward the ferroelectric transition at 63 K. The measured values of $T_1$ for ammonium and hydrogen-bond protons are similar in the whole range of temperature. $T_1$ of $^1H$ NMR shows a gradual decrease down to 120 K and starts to steeply increase below 100 K. Then $T_1$ shows abrupt decrease below 70 K with a sharp minimum at 63 K, where the ferroelectric transition occurs. This temperature dependence of spectrum and $T_1$ clearly prove that the large change in the dynamics of hydrogen bond network is associated with the ferroelectric phase transition at 63 K.

• Journal of the Mineralogical Society of Korea
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• v.25 no.2
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• pp.77-84
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• 2012

Anatase, one of the $TiO_2$ polymorphs, is known to show different phase transition paths depending on its crystalline and shape. Particle size of 15~25 nm anatase has been subjected to high-pressure Raman spectroscopy and X-ray diffraction studies using a diamond anvil cell. We observe that the starting sample transforms to an amorphous phase above approx. 20 GPa, which is retained upon pressure release to ambient condition. This is in contrast to previously established transition to baddeleyite phase and we suspect difference in the particle distribution state trigger phase instability of nanoparticles and hence amorphization.