• Advances in nano research
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• 제8권2호
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• pp.103-114
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• 2020

In this research, buckling and free vibration of rectangular polymeric laminate reinforced by graphene sheets are investigated. Various patterns are considered for augmentation of each laminate. Critical buckling load is evaluated for different parameters, including boundary conditions, reinforcement pattern, loading regime, and laminate geometric states. Furthermore, vibration analysis is investigated for square laminate. Elastic properties of the composite are calculated using a combination of both molecular dynamics (MD) and the rule of mixture (MR). Kinematics of the plate is approximated based on the first shear deformation theory (FSDT). The current analysis is performed based on the energy method. For the numerical investigation, Ritz method is applied, and for shape functions, Chebyshev polynomials are utilized. It is found that the number of layers is effective on the buckling load and natural frequency of laminates which made from non-uniform layers.

• 대한설비공학회지:설비저널
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• 제15권2호
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• pp.182-187
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• 1986

Experimental measurements of the heat transfer and heat flux to a jet impinging on a heated surface were obtained in the nucleate boiling regimes. Tes-variables were jet at velocity and aspect ratio ($b/\ell$) of the heated surface. A slope of nucleate boiling curve increased with increasing the aspect ratio of the heated surface, namely approaching a rectangular square, and it is shown that surface tension has an important role for the onset of nucleate boiling heat transfer. A generalized correlation of the jet nucleate boiling heat transfer. A generalized correlation of the jet nucleate boiling heat transfer was found using a pi theorem.

• 소성∙가공
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• 제8권4호
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• pp.356-363
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• 1999

This paper discusses some techniques for the determination of optimum blank size and pre-form design for multi-stepped deep drawing of oval shell. The deep drawing process of oval shape has been regarded as more difficult than that of cylindrical shell because of its complicated behavior of plastic deformation. But there is insufficient information in this area to carry out successful deep drawing work of irregular products such as oval, rectangular, and square shapes. In order to find the optimum conditions, the drawing apparatus for two kinds of pre-form design are built, a series of drawing experiments performed, and thickness stain distributions measured. From the results of thess suggested experiments, various optimum process variables are observed and discussed.

• 고문화
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• 61호
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• pp.3-44
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• 2003

한반도에서의 주거 평면구조는 일반적으로 원형$\rightarrow$방형$\rightarrow$장방형의 순으로 변천하고 있다. 주거의 출입구조는 계단식과 돌출되어 있는 경우, 주거 벽면에서 경사진 구조 등이 있고, 주거바닥은 주로 생토층과 모래바닥을 이용하며, 진흙이나 조개껍질을 깐 경우도 있다. 저장시설은 화덕자리의 주변이나 주거의 벽가에 두고 있으며, 화덕자리는 중앙의 1개소가 일반적이다. 기둥구멍은 벽가를 따라 배치되거나, 각 모서리에 배치되는 경우, 혹은 주거지의 내부와 외부에 동시에 존재하기도 한다. 지붕구조는 낮은 원추형에서 기둥을 걸쳐서 만드는 양면경사의 방형이나 장방형으로 변하며, 주거의 내부공간은 수면이나 취사 이외에도 작업장, 의례 등 여러 기능이 복합적으로 이루어지고 있다. 주거는 기본적으로 1기에 1칸의 구조를 보이고 있으며, 내부에서 남녀의 공간적 사용범위가 정해져 있다. 신석기시대의 취락은 환상이나 호상형태로 중앙에 광장이 있으며, 주거 밀집지역에 공공장소가 존재한다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 추계 학술대회논문집
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• pp.62-69
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• 1998

Spiral tube heat exchangers can find numerous applications in many engineering field. Flow in spital tubes is interest to engineers due to occurrence of secondary flow which enhances the cross-sectional mixing and the heat transfer rate. In the present study, an incompressible viscous 3-D flow in spiral tubes with rectangular cross-section of various torsion rate and Reynolds number is studied by using a finite volume method. It is shown that the axial velocity profile is affected by the secondary flow motion. Because there is some difference from correlation proposed by Hur et al., a lot of analysis and arrangement of experimental results are needed. This study showed the results of variation of hydrodynamic entry length for torsion and Re numbers.

• 한국정밀공학회지
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• 제18권9호
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• pp.71-81
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• 2001

This paper analyzes the effectiveness of minimizing vibration and sound transmission on/through a thin rectangular plate by both feedback control and hybrid control which combines adaptive feedforward control with a feedback loop. An experimental system identification technique using the matrix-fractional curve-fitting of the frequency response data is introduced for complex shaped structures. This identification technique reduces the model order o the MIMO(Multi-Input Multi-Output) system which simplifies the practical implementation. The adaptive feedforward control uses a Multiple filtered-x LMS(Least Mean Square) algorithm and the feedback control uses a multivariable digital LQG(Linear Quadratic Gaussian) algorithm. Experimental results show that an effective reduction of sound transmission is achieved by the hybrid control scheme when both vibration and noise measurement signals are incorporated in the controller.

• 디지털산업정보학회논문지
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• 제9권2호
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• pp.11-15
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• 2013

We in order to use WLAN communication device planned wireless USB dongle internal antenna of 2.4 GHz/5.8 GHz band. So it uses square patch dual-wideband and quality is satisfactory and it designed print folded monopole antenna of the shape which is simple. The thickness of the antenna was fed by a $50{\Omega}$ coaxial cable feeding 1mm dielectric constant 4.4 FR4 substrate was used. The overall size of the antenna is $20mm{\times}50mm$. So the internal antenna is suitable. Measurement results of the fabricated antenna, the return loss of more than 10 dB in the two bands could be obtained. Radiation pattern has a maximum gain of 3.75 dBi value.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.550-555
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• 2003

When a shock wave arrives at an open end of tube, an impulse wave is discharged from the tube exit and complicated flow is formed near tube exit. The flow field is influenced by the cross-sectional geometry of tube exit, such as circular, square, rectangular, trapezoid and etc. In the current study, three-dimensional propagation characteristics of impulse wave discharged from the tube exit with non-circular cross section are numerically investigated using a CFD method. Total variation diminishing (TVD) scheme is used to solve the three-dimensional, unsteady, compressible Euler equations. Computations are performed for the Mach numbers of the incident shock wave $M_{s}$ below 1.5. The results obtained show that the peak pressure of the impulse wave and propagation directivity depends on the cross-sectional geometry of tube exit and the Mach number of incident shock wave.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.747-749
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• 2003

When the input current wave forms of Linear Pulse Motor(LPM) is excited as three difference type such as the square, the rectangular and the micro sinusoidal wave, this paper is proposed the calculation of thrust on the base of magnetic equivalent circuit of LPM. The thrust is analyzed and compared by the analytical method, the F.E.M. and the experimental values. Also, to decide the input current wave for optimal operation condition, the vibration of LPM is experimented and estimated.

• 한국전자통신학회논문지
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• 제14권1호
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• pp.55-60
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• 2019

무선 인터넷의 수요가 급증하여 기존에 사용된 2.4 GHz 대역의 통신은 포화상태가 되었으며 혼선이 잦아지고 여러 가지 장애가 발생하게 되었다. 이에 따라 5 GHz 대역의 무선 인터넷 기술 개발이 진행 되었다. 본 논문에서는 5 GHz 대역의 무선통신이 가능한 사각형 슬롯 마이크로스트립 패치 안테나를 연구하였다. 연구는 HFSS를 통해 안테나를 설계 및 분석 하였고 포토리소그래피법을 이용해 안테나를 실제 제작 하였다. 최종적으로 제작된 안테나를 회로망 분석기를 통해 특성을 비교 및 분석하였다.