• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.5
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• pp.485-490
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• 2015

This paper presents development of a geometrically nonlinear triangular planar element including rotational degrees of freedom, based on the co-rotational(CR) formulation. The CR formulation is one of the efficient geometrically nonlinear formulations and it is based on the assumptions on small strain and large rotation. In this paper, modified CR formulation is suggested for the developemnt of a triangular planar element. The present development is validated regarding the static and time transient problems. The present results are compared with the results predicted by the previous researchers and those obtained by the existing commercial software.

• The Journal of the Korea Contents Association
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• v.6 no.4
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• pp.136-145
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• 2006

The main purpose of the present study was to find the effect of short term creatine loading on repeated bouts of kicking, plasma creatine phosphokinase and anaerobic power in male taekwondo player from high school. Eighteen male were randomly assigned to two groups. They were tested before and after 6 days of placebo($4{\times}5$ glucose d-1, N=9) or Creatine monohydrate loading(consume 0.3g kg-1, N=9). Only creatine loading group were significantly increased of repeated bouts of kicking, plasma creatine phosphokinase and anaerobic power These results suggest that short creatine loading was effective diet protocol in taekwondo player from male high school.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.4
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• pp.209-216
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• 2020

In this paper, parametric structural analysis is presented utilizing the co-rotational(CR) shell analysis utilizing EDISON. CR shell analysis shows faster convergence than the commercial software, NASTRAN, does. The 1st natural frequency of the rear frame is obtained, which is close to that of the engine during high speed cruise. Three cases under two design variables are presented and analyzed. Gusset is shown to be more effective among those which feature the same weight change. The results presented in this paper will be applicable for further researches to improve the durability of a motorcycle rear frame.

• Journal of Korean Ophthalmic Optics Society
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• v.4 no.2
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• pp.23-31
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• 1999

The purpose of this study is to evaluate the relationship between axial length/corneal radius ratio and refractive error for human eye. Ocular components were measured Baush & Lomb keratometer, Holden-Payor pachometer, and Stoz Compuscan. Refractive error was measured by subjective refraction. The results were as follows; 1) Spherical equivalent refractive error and axial length/corneal radius ratio was very highly correlated with the correlation coefficient for -0.89. 2) Axial length/corneal radius ratio and axial length, vitreous chamber depth were highly correlated that the correlation coefficients were 0.82, 0.80 respectively. 3) Axial length/corneal radius ratio and anterior chamber depth, corneal power, corneal radius, lens power were correlated with the correlation coefficients for 0.57, 0.40, -0.39, -0.35 respectively. 4) There were no significant correlation between axial length/corneal radius ratio and lens thickness, and corneal thickness.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.1946-1953
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• 2006

Because the embedded watermark of luminance component guarantees the extraction of ownership information when the color image is converted to gray scale image, the information of ownership right as to the luminance component is embedded in the luminance-chrominance color space such as YCbCr. Therefore, this paper proposes watermark embedding, extraction and authentication algorithm of color image. which considers the device and performance of multimedia contents service by focusing on the robustness and invisibility of watermark. The color image is converted from RGB color space to YCbCr color space, and then the properties of each component of Y(Luminance), Cb(Color Differences) and Cr(Color Differences) are considered in order to embed, extract and certify multi-level watermark in the frequency domain based on the wavelet. As a result, it can guaranteed the robustness for the JPEG compression and invisibility of watermark for multi-level.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.2
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• pp.115-121
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• 2011

The size of hydrogen molecule is not so small as to invade into the lattice of material, and therefore, hydrogen invades into the material as atom. Hydrogen movement is done by diffusion or dislocation movement in the near crack tip or plastic deformation. Hydrogen appeared to have many effects on the mechanical properties of the Cr-Mo steel alloys. The materials for this study are 1.25Cr-0.5Mo and 2.25Cr-1Mo steels used at high temperature and pressure. The hydrogen amount obtained by theoretical calculation was almost same with the result solved by finite element analysis. The distribution of hydrogen concentration and average concentration was calculated for a flat specimen. Also, finite element analysis was employed to simulate the redistribution of hydrogen due to stress gradient. The calculation of hydrogen concentration diffused into the material by finite element method will provide the basis for the prediction of delayed fracture of notched specimen. The distribution of hydrogen concentration invaded into the smooth and notched specimen was obtained by finite element analysis. The hydrogen amount is much in smooth specimen and tends to concentrate in the vicinity of surface. Hydrogen embrittlement susceptibility of notched specimen after hydrogen charging is more remarkable than that of smooth specimen.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.2
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• pp.120-126
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• 2016

In this study, we propose a method for effectively detecting and recognizing the face in image using RBFNNs pattern classifier and HCbCr-based skin color feature. Skin color detection is computationally rapid and is robust to pattern variation for face detection, however, the objects with similar colors can be mistakenly detected as face. Thus, in order to enhance the accuracy of the skin detection, we take into consideration the combination of the H and CbCr components jointly obtained from both HSI and YCbCr color space. Then, the exact location of the face is found from the candidate region of skin color by detecting the eyes through the Haar-like feature. Finally, the face recognition is performed by using the proposed FCM-based RBFNNs pattern classifier. We show the results as well as computer simulation experiments carried out by using the image database of Cambridge ICPR.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.421-425
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• 2009

A study has been performed to investigate the thermo-mechanical effects of thermal barrier coating on liquid rocket regenerative cooling chamber using finite element analysis. Two kinds of thermal barrier coatings were studied on the same loading condition: first, NiCrAlY-$ZrO_2$, coating which is currently applied to the developing combustion chamber and second, Ni-Cr coating which might be applied in the future. Analysis results showed that NiCrAlY-$ZrO_2$ coating has better decreasing effect of temperature than the Ni-Cr coating. As a results, temperature and deformation of the cooling channel in the NiCrAlY-$ZrO_2$ coating were also less than those of the Ni-Cr coating. The Ni-Cr coating has no effect on a structural stability of the outer jacket but the NiCrAlY-$ZrO_2$ coating reduced the effective stress of the outer jacket and enhanced the structural stability of the chamber.

• Journal of the Korean Magnetics Society
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• v.4 no.1
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• pp.20-24
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• 1994

The read/write characteristics of CoCr/NiFe double layered media are strongly affected by the magnetic properties of NiFe magnetic soft layer as well as those of CoCr recording layer. Modification of the permalloy layer by NiFe/Ge multilayer scheme resulted in the higher recording sensitivity and the higher reproduced voltage of CoCr/NiFe medium and this is attributed to the higher permeability of the back layer and high perpendicular anisotropy of the CoCr recording layer. Although higher permeability of back layer results in higher recording sensitivity, the increment of the reproduced voltage was not remarkable, which can be confirmed in the FEM numerical analysis. On the contrary, peak shift characteristics of the CoCr/NiFe medium with the NiFe multi back layer was deteriorated compared to that of the CoCr/NiFe medium with NiFe single back layer. Insertion of ferromagnetic thin CoZrNb intermediate layer between CoCr and NiFe layer was effective to ensure large reproduced voltage and low peak shift. These recoridng characteristics were also discussed in connection with microstructural characteristics.

• Journal of the Korean Chemical Society
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• v.48 no.4
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• pp.358-366
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• 2004

The bridged disulphato complex $[Cr_2(NH_2)_2(H_2O)_2(SO_4)_2]{\cdot}2H_2O$, terminal triisocyanato $[Cr(NCO)_3(H_2O)]{\cdot}3H_2O$ complex and limonite, $[FeO(OH)]{\cdot}0.2H_2O$ compound were prepared by the reaction of $Cr_2(SO_4)_3{\cdot}xH_2O, Cr(CH_3COO)_3$ and $Fe_2(SO_4)_3$, respectively, with urea in aqueous media at $80^{\circ}C$. The infrared spectra of the products indicate that the absence of the bands of urea, but shows the characteristic bands of coordinated amide, water, bridged sulphato and isocyanato groups. Thermogravimetric (TG) and differential thermal analysis (DTA) measurements on the complexes are also recorded. The data obtained agree quite well with the expected structures. A general mechanisms describing the formation and its thermal decomposition of the complexes are suggested.