• 한국해양공학회지
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• 제22권6호
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• pp.7-12
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• 2008

The present study numerically investigates the effect of the shape of absorbing revetment on wave overtopping rate under regular and irregular incident waves. At first, the numerical model developed by Hur and Choi(2008), which considers the flow through a porous medium with inertial, laminar and turbulent resistance terms, directly simulates Wave-Structure-Sandy seabed interaction and can determine the eddy viscosity with LES turbulent model in 2-Dimensional wave field (LES-WASS-2D), is validated when compared to experimental data. Numerical simulations are then performed to examine the effect of the shape of absorbing revetment and incident wave conditions on wave overtopping rate. The numerical result shows that the wave overtopping rate decreases with the slope gradient of absorbing revetment under both regular and irregular waves. In addition, the effects of mean grain size and porosity of absorbing revetment, incident wave period and crest height on wave overtopping rate are discussed.

• Wind and Structures
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• 제37권1호
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• pp.1-13
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• 2023

Due to the irregular shape and the deviation of stiffness center and gravity center, buildings always suffer from complex surface load and vibration response under wind action. This study is dedicated to analyze the surface wind load and wind-induced response of an irregular building, and to discuss the possibility of top swimming pool as a TLD to diminish wind-induced vibration of the structure. Wind tunnel test was carried out on a hotel with irregular shape to analyze the wind load and structural response under 8 wind incident angles. Then a precise numerical model was established and calibrated through experimental results. The top swimming pool was designed according to the principle of frequency modulation, and equations of motion of the control system were derived theoretically. Finally, the wind induced response of the structure controlled by the pool was calculated numerically. The results show that both of wind loads and wind-induced responses of the structure are significantly different with wind incident angle varies, and the across-wind response is nonnegligible. The top swimming pool has acceptable damping effect, and can be designed as TLD to mitigate wind response.

• 한국기계가공학회지
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• 제10권1호
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• pp.16-22
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• 2011

Recently, the deburring process which is last process of manufacture is one of the important process for complete product. The development of shape guided automatic deburring machine is essential because manual deburring process has very irregular quality and higher error rate as well as consider irregular shape radius. In order to develop of shape guided automatic deburring machine, in this study, we conducted 3D design, assembly, machine simulation and structural analysis using CATIA. Also, we conducted to make automatic deburring machine and conducted a performance test.

• 한국결정성장학회지
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• 제32권1호
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• pp.33-39
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• 2022

3D 프린터 관련 특허가 만료되고 주요 기술이 공개되면서 3D 프린터 가격이 하락하면서 원하는 제품을 쉽게 찾을 수 있는 환경이 조성되고 있다. 특히 가장 저렴한 FDM(Fused Deposition Modeling) 3D 프린터가 다양한 분야에서 사용되고 있다. FDM 방식은 형상을 출력할 때 특정 조건이상에서는 지지대(Support)를 붙여야만 형상의 무너짐 없이 제작이 가능하다. 지지대를 달지 않고 형상을 출력할 때 특정 각도에서 발생하는 불규칙한 표면은 제품에 있어서는 불량이지만 예술과 공예적 측면에서는 또 다른 재미를 느낄 수 있는 요소로 활용될 수 있다고 사료된다. 본 논문에서는 이러한 불규칙한 표면을 얻기 위해 출력에 영향을 줄 수 있는 요인들을 제어하고 출력 각도만 변위요소로 실험하였다. 실험 결과 수직에서 62°~70°의 각도로 프린팅 시 필라멘트가 흘러내리지 않고 불규칙한 표면을 얻을 수 있었다. 또한 인위적으로 불규칙한 표면을 공예적인 제품에 적용해 보았다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1097-1100
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• 2004

A rear axle spider in an irregular shape, which is used as a part in the braking system of a vehicle like a big truck and a trailer, is subjected to a large torque and hence requires both strength and endurance over the brake heat. This part should be therefore manufactured in dimensional accuracy. The practical manufacturing process of this irregular product requires the heat treatment process after hot forging and then the cold coining process for the dimensional accuracy. At the present study, the warm coning without the heat treatment process was proposed to employ the residual heat due to the hot forging process. And also the trimming and piercing process was designed using the rigid-plastic finite element method. The mechanical properties were discussed and also commented upon.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.426-429
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• 2004

To reconstruct the 3-D information of a irregular object, this paper proposes a new method applying the composition focus measure to time-series image. A focus measure function is carefully selected because a focus measure is apt to be affected by the working environment and the characteristics of an object. The proposed focus measure function combines the variance measure which is robust to noise and the Laplacian measure which, regardless of an object shape, has a good performance in calculating the focus measure. And the time-series image, which considers the object shape, is proposed in order to efficiently applying the interesting window. This method, first, divides the image frame by the window. Second, the composition focus measure function be applied to the windows, and the time-series image is constructed. Finally, the 3-D information of an object is reconstructed from the time-series images considering the object shape. The experimental results have shown that the proposed method is suitable algorithm to 3-D reconstruction of an irregular object.

• 한국안광학회지
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• 제1권1호
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• pp.15-22
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• 1996

본 연구는 망막조직의 미세구조를 전자현미경을 이용하여, 생쥐(ICR)에 대한 Laser 조사의 영향을 조사하였다. 그 결과는 다음과 같다. l. 정상군에서 대개의 망막층은 여러 특수한 세포들과 신경섬유로 구성된 복잡한 구조를 가지고 있었다. 2. Laser 조사의 기간이 길어질수록, 망막의 각 세포의 층과 구조는 일정한 형태를 나타내지 못했다. 시세포 visual cell들은 심하게 이형염색질체 heterochromatin이며, 세포질은 종대되며, 핵의 모양은 불규칙적이며,일부의 세포질은 소실되었다. 망막층의 핵과 신경섬유는 매우 불규칙적이며, 소포의 형성, 각 세포간 경계의 불명확함이 있었다. 색소상피세포 pigment epithelail cell들은 정상모양이 아니며, 세포질에는 큰 공포 형성이 있으며, 핵의 응축과 불규칙한 모양 등이 있었다.

• 한국기계가공학회지
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• 제3권3호
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• pp.5-10
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• 2004

The effect of bronze sintered friction materials on frictional and mechanical properties is studied with the content(8~18 wt,%) and shapes (flake and irregular) of graphite that is used as solid lubricants to meet diverse characteristics such as low coefficient of friction, low wear rate and high bending strength. The content and shapes of graphite are optimized by statistical experiments. Friction test was carried out measure friction coefficient, temperature dependence and wear rate. As a result of experiments, the density, hardness and bending strength with a shape of flake graphite are lower and decrease rapidly than that of Irregular, as the content of graphite increases up to 18 wt% Aftei friction test, coefficient of friction is 0.3~0 4 and wear rate is $0.32{\sim}2.98{\times}10^{-7}cm^3/kg{\cdot}m$. When the content of graphite increases, coefficient of friction increases In a shape of flake graphite and decreases in a shape of irregular graphite.

• 생약학회지
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• 제26권4호
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• pp.411-418
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• 1995

In order to clarify the originality of several Alisma Rhizomes, we investigated the differences of their morphological, anatomical and physiochemical characteristics. Morphological observation shows the variability of Alisma shape and quality. The diversities in morphological shapes and qualities of tuber were observed among different origins. Chinese product looked like corm shape, but korean's irregular shape. The microscopic observation of korean Alisma revealed the presence of irregular vascular bundle which was scattered transversely and longitudinaly, which was different from that of the rhizome. This facts suggest that the portion of crude drug in Alisma should be the corm rather than the rhizome. In the physicochemical differences, chinese Alisma contains larger amount of mineral elements such as K, Na and Ca than korean Alisma. On the contrary, protein contents in lyophilized powder of aqueous extracts in korean Alisma rhizome was significantly higher than chinese Alisma rhizome. The leaves and stems contained larger amount of Ca and Na than tuber, and may be used as the osmotic diuretics for chinese traditional medicine.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.503-504
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• 2006

The MIM technology is an alternative process for fabricating near net shape components that usually uses gas atomised powders with small size $(<\;20\;{\mu}m)$ and spherical shape. In this work, the possibility of changing partially or totally spherical powder by an irregular and/or coarse one that is cheaper than the former was investigated. In this way, different bronze 90/10 components were fabricated by mixing three different types of powder, gas and water atomised with different particle sizes, in order to evaluate how the particle shape and size affect the MIM process.