• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.1
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• pp.132-150
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• 2014

In this study, the inertial properties of fully filled liquid in a tank were studied based on the potential theory. The analytic solution was obtained for the rectangular tank, and the numerical solutions using Green's 2nd identity were obtained for other shapes. The inertia of liquid behaves like solid in recti-linear acceleration. But under rotational acceleration, the moment of inertia of liquid becomes small compared to that of solid. The shapes of tank investigated in this study were ellipse, rectangle, hexagon, and octagon with various aspect ratios. The numerical solutions were compared with analytic solution, and an ad hoc semi-analytical approximate formula is proposed herein and this formula gives very good predictions for the moment of inertia of the liquid in a tank of several different geometrical shapes. The results of this study will be useful in analyzing of the motion of LNG/LPG tanker, liquid cargo ship, and damaged ship.

• YAKHAK HOEJI
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• v.24 no.2
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• pp.135-141
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• 1980

The crystal and molecular structure of 2-methyl-3-(N-trimethyl ammonium)phenol iodide, $C_{10}H_{16}NOI, was determined by X-ray diffraction method. The compound crystallizes in the orthorhombic space group $P_{na2}_{1}$ with a=13.327(3), b=12.496(3), C=7.227(2)A and Z=4. A total of 489 independent observed reflections were collected by the automated Four-circle diffractometer and was solved by heavy atom method and refined by anisotropic block-diagonal least-squares method to the R value of 0.04. The benzene ring is slightly distorted from regular hexagon. The I atom and 2-methyl-3-(N-trimethyl ammonium)phenol group is held together by van der Waals forces in the crystal. Intermolecular hydrogen bond is of the type O-H....I with the length 3.35.angs.. Apart from the hydrogen bonding system the molecules are held together by van der Waals forces in the crystal.

• Structural Engineering and Mechanics
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• v.70 no.2
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• pp.153-168
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• 2019

In this paper, energy absorption characteristics of circular windowed tubes with different section shapes (circular, ellipse, square, hexagon, polygon and pentagon) are investigated numerically and experimentally. The tube possesses the same material, thickness, height, volume and average cross sectional area which are subjected under axial and oblique quasi-static loading conditions. Numerical model was constructed with FE code ABAQUS/Explicit, the obtained outcome of simulation is in good matching with the experimental data. The energy absorbed, specific energy absorption, crash force efficiency, peak and mean loads along with the collapse modes with their initiation point of simple and windowed tubes were evaluated. The technique for order of preference by similarity ideal solution (TOPSIS) approach was employed for assessing their overall crushing performances. The obtained results confirm that efficacy of crash force indicators have improved by introducing windows and tubes with pentagonal and circular windows achieves the maximum ranking about 0.528 and 0.517, it clearly reveals the above are best window shapes.

• Advances in materials Research
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• v.12 no.4
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• pp.309-330
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• 2023

The humid thermal vibration characteristics of a nonhomogeneous thermopiezoelectric nonlocal plate of polygonal shape are addressed in the purview of generalized nonlocal thermoelasticity. The plate is initially stressed, and the three-dimensional linear elasticity equations are taken to form motion equations. The problem is solved using the Fourier expansion collocation method along the irregular boundary conditions. The numerical results of physical variables have been discussed for the triangle, square, pentagon, and hexagon shapes of the plates and are given as dispersion curves. The amplitude of non-dimensional frequencies is tabulated for the longitudinal and flexural symmetric modes of the thermopiezoelectric plate via moisture and thermal constants. Also, a comparison of numerical results is made with existing literature, and good agreement is reached.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.330-332
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• 2007

본 논문에서는 정수 단위 화소 움직임 예측(ME: Motion Estimation)을 위한 Unsymmetrical-cross Multi-Hexagon-grid Search (UMHexagonS) 알고리즘을 기반으로, CIF 크기의 영상을 실시간으로 부호화 하기 위한 정수 단위 화소 움직임 예측 모듈을 제안한다. 제안하는 정수 단위 화소 움직임 예측 모듈은 32 개의 1 차원 연산유닛(PE: Processing Element) 배열, 데이터 선택/재배열 유닛, 내부버퍼, 그리고 트리 구조의 덧셈기로 구성되며, CIF 크기의 영상 100 프레임을 부호화 하기 위한 클럭 사이클을 계산하여 실험결과로 제시하였다. 그 결과 제안하는 구조는 400MHz 의 클럭 속도에서 CIF 크기의 영상을 실시간으로 부호화 할 수 있다.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.185-195
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• 2011

In this study, titanium abutments and zirconia abutments were connected to each implant in external type implants. After that they were loaded 10000 times with 20Kg as occlusal force. The surface changes of external hexgon part and platform were observed in FESEM image. Viker's hardness of an implant, a titanium abutment and a zirconia abutment were measured respectively. 1. Viker's hardness of an implants, a titanium abutment and a zirconia abutment was $309.80{\pm}11.78$ HV, $318.40{\pm}11.82$ HV, and $1495.30{\pm}16.21$ HV respectively. There was no statistical significance between an implant and a titanium abutment (P>0.05, Anova). However, there was statistical significance between an implant and a zirconia abutment(P<0.05, Anova). 2. The wear was observed at the joint of implant and abutment in both a titanium abutment group and a zirconia abutment group after loading 10,000 times. The zirconia abutment showed more remarkable wear than the titanium one. In conclusion, the wear of external hexagon and platform was much more notable in a zirconia abutment group than a titanium one. It was suggested that it could result from the difference of surface hardness between titanium and zirconia. The wear of junction between an implant and a zirconia abutment becomes more severe, the connection of an implant and an abutment is much more unfit. This is likely to cause loosening and fracture of the abutment screw. so it is considered that the possibility of implant supra-structure failure can be increased.

• Geophysics and Geophysical Exploration
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• v.11 no.3
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• pp.230-241
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• 2008

Characteristics of transfer responses for arrays like triangle, hexagon and semicircle were investigated. To characterize the site near Izmit city with ambient noise measurement, dispersion curves of surface waves were derived with using array technique like F-K, High resolution F-K, MSPAC and H/V ratio was calculated. Also, MASW was surveyed to get the high frequency part of dispersion curves. The transition from fundamental mode to first high mode of surface waves for dispersion curve was observed. Dispersion curve of fundamental mode of ambient noise and first higher mode of MASW was used in inversion to get S-wave velocity structure of subsurface. None-unique problem of results of surface wave inversion was solved with comparison of result of refraction tomography performed with first arrivals of MASW data.

• Journal of computational fluids engineering
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• v.16 no.2
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• pp.66-74
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• 2011

The SCR catalyst in coal-fired power plant is eroded by the collision of fly ash on the catalyst surface. However the erosion of SCR catalyst by the collision of fly ash has not been fully studied, especially in terms of fluid dynamics. Hence, in the present study, we focus on the gas and solid flows inside the SCR catalyst duct and their consequent effect on the erosion characteristics. For this purpose, computational fluid dynamics is applied to investigate the two-phase flows and to evaluate the erosion rate for different flow and particle injection conditions. Also, the erosion rate and pressure drop of commonly used square shape are compared with equilateral triangle and hexagon shapes. The pressure drop of SCR catalyst is increased when SCR catalyst surface area per unit volume increases. The erosion rate of SCR catalyst is enhanced when the particle velocity, mass flow rate of particle, particle diameter and cell density of SCR catalyst are increased. From the results, the pressure drop and erosion rate at the catalyst surface can be minimized by reducing cell density of SCR catalyst to decrease particle velocity and number of particle impacts.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.143-143
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• 2012

In/Si (111)-$4{\times}1$ 표면은 저온에서의 $8{\times}2$ 주기의 상과 상온에서의 $4{\times}1$ 주기의 상 사이에 상전이가 나타나는 것으로 알려져 있다. 지금까지의 연구에 의하면 저온 $8{\times}2$ 주기의 상에서는 최근 제시된 hexagon 구조 모형이 가장 설득력 있게 받아들여지고 있으나, 상온 $4{\times}1$ 주기의 상에 대해서는 정적인(static) 구조 모형과 동적요동(dynamic fluctuation) 모형이 제안되었다. 이 두 가지 구조 모형은 모두 2차 상전이를 의미하지만, 최근 엔트로피를 고려한 이론계산 결과는 이 상전이가 1차 상전이를 가짐을 시사하였다. 그래서 우리는 이 표면의 상전이를 저에너지전자회절 실험을 통하여 연구하였고, 온도를 상온에서 저온으로 낮출 때와 저온에서 상온으로 높일 때의 회절세기 변화로부터 가열과 냉각의 두 과정에서 상전이 온도가 서로 다르게 나타나는 히스테리시스 곡선을 보임을 관찰하였다. 이는 주사터널링현미경 이미지에서 $4{\times}1$ 상온 구조와 $8{\times}2$ 저온 구조가 상전이 온도 근처에서 공존하는 것으로 관찰되는 것과 상통하는 결과로 1차 상전이임을 나타낸다. 이에 우리는 이 표면의 구조 상전이가 1차 상전이인 것으로 결론지으며, 이와 함께 표면의 결함이 상전이에 미치는 영향에 대해서도 논의할 것이다.

• Korean Journal of Computational Design and Engineering
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• v.17 no.6
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• pp.426-435
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• 2012

This paper starts with an approach to Korean traditional building design using BIM tool as a design methodology where Korean traditional buildings show some difference rather as weaknesses in handling curves and curved members and the construction. BIM design tools, that are adequate in treating modern architectural design vocabularies, show some disadvantages not having necessary elements and components as building libraries. In this paper we build our own libraries adequate to the proper assembling way of Korean traditional buildings. In contrast to the diverse use of straight building members, Korean traditional buildings show rare use of curves and/or curved members in their assemblage. Moreover, in the case of a circular plan, mostly a circle is interpreted in terms of polygons such as square, hexagon or octagon. In this paper, we examine Gwanram-Jung in Changduk Palace, which is probably the only example in Korea showing a use of curves and/or curved members in assemblage. We try to interpret the case as an incomplete prototype and apply in a modern way to complete a circular plan in terms of circular arcade.