• 한국항공운항학회:학술대회논문집
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• 2016.05a
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• pp.19-22
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• 2016

본 연구는 박각시 나방 유연날개의 준정상 공력 모델링을 위한 공력측정실험을 진행하였다. 두 개의 서보모터로 이루어진 동역학적 로봇 모델은 3톤 수조 내부에서 날갯짓 운동을 구현하였고, 6축 센서가 날개 모델의 뿌리에 장착되어 공력 측정을 시행하였다. 날개 모델은 다른 두께의 폴리카보네이트 평판으로 제작되었고, 3mm 두께의 강체날개와 0.8mm 두께의 유연날개로 구성되었다. 공력측정은 각 날개 모델별 받음각을 -5도에서 95도까지 5도씩 변경하여 진행하였고, 이를 바탕으로 준정상 공력 모델링을 시도하였다. 날개 두께별 준정상 공력 모델링을 통해 특정 두께를 가진 유연날개는 강체날개보다 높은 공력효율을 가짐을 알 수 있었고, 날개 유연도 역시 준정상 가정을 기반으로 모델링 할 수 있을 것으로 기대된다.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.293-298
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• 2004

We investigate the effect of the wing width and thickness of a Double-Sided Deep-Ridge(DSDR) vertical directional coupler on the coupling length dependent on the polarization, We have found that the DSDR vertical directional coupler without a wing does not have polarization independent coupling lengths. The variation of the coupling length of TE and TM modes and the difference between the coupling lengths of the two modes are negligible as the wing width increases beyond the specific wing width for the same wing thickness. Thus, we can see that a DSDR vertical directional coupler has a wing width larger than the minimum wing width to obtain the polarization independent coupling length. The minimum wing width increases as the wing thickness increases for the same core thickness and as the core thickness decreases for the same wing width. Also, we have found that the minimum wing thickness is determined by the core thickness and the minimum wing thickness decreases as the core thickness increases.

• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.135-141
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• 1998

Some sized centrifugal compressor were designed and their performance measured to investigate the effects of exit blade thickness, width and back swept angle. The impeller of larger blade thickness shows low pressure ratio compared with that of smaller one. Backswept angle have also large effect on the efficiency. Measured values of slip factor are quite different from the estimated values of Wiesner-Busemann model and increase with the flow rate.

• The KSFM Journal of Fluid Machinery
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• v.2 no.1 s.2
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• pp.15-21
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• 1999

Some sized centrifugal compressors were designed and their performance measured to investigate the effects of exit blade thickness, width and back swept angle. The impeller of larger blade thickness shows low pressure ratio compared with that of smaller ones. Backswept angle also have a large effect on the efficiency. Measured values of slip factor are quite different from the estimated values of the Wiesner-Busemann model and an increase in the flow late.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.3
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• pp.29-40
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• 1999

A numerical method in frequency domain for the analysis of the acoustic wave equation governing the sound field generated by a non-cavitating propeller under a steady of unsteady loading condition is developed. Theory shows that only multiples of the blade passage frequency exist and that the wave number consists of the frequency component due to the nonuniformity of the wake and the Doppler effect originated from the rotation of the blades. Correlation with experiments for a two bladed propeller, designed to be load-free at a particular advance speed, indicate that the thickness effect can be significant in steady case, but can be negligible compared to the unsteady loading effect.

• Composites Research
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• v.25 no.6
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• pp.224-229
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• 2012

The structural performance is degraded in case of embedding the array antenna for reconnaissance and surveillance into the wing skin structures. In this paper, the optimal design for the thickness of composite hat-shaped stiffener which is reinforced embedded array antenna on the simplified composite wing box was conducted. To select the basic shape of hat-shaped stiffener, structural analysis was carry out using the commercial finite element analysis program while changing the web slope and flange length of hat-shaped stiffener. The optimal thickness of the composite hat-shaped stiffeners was determined by using commercial optimization program such as VisualDOC and commercial FEA program with considering stresses and buckling constraints.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.1
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• pp.11-23
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• 1997

This paper contains a new approach to blade section design method for marine propellers. The hydrodynamic characteristics of 2-D section are highly influenced by its geometrical parameters i.e., thickness and camber distributions and leading edge radius etc. To consider fully turbulent flow field near 2-D section. the finite volume method with k-${\varepsilon}$ turbulent model which solve Reynolds time averaged Navier-Stokes(RANS) equation is applied. In this study, O-type grid system that can provide many calculation points on blade surface is used. The results were compared with those of the experiment of NACA0012 to confirm the accuracy of the developed codes. The goal of this study is the development of a blade section with high efficiency and low drag. To achieve this, we carried out the tests of lift, drag and cavitation characteristics in cavitation tunnel. The results of experiment were compared with numerical results in order to validate the proposed blades design method. By comparing the numerical results with the experiments, we found that the new blade section, KH28 allows superior performance in efficiency and cavitation avoidance characteristics. We further investigated the blade section design method and an application study of this section, KH28 to apply to the marine propeller. In order to improve the accuracy of numerical results on prediction of lift and drag, we conclude here that the 2-layer boundary model must be used.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1634-1635
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• 2011

송전선로 및 배전선로에 사용되는 애자의 날개부분(shed)의 두께는 연면거리에 비해서 매우 얇다. 가령 매우 높은 전압이 애자에 인가되는 경우, 그 날개부분을 통해서 관통파괴가 일어날 수도 있다. 따라서 시험규격에는 그 부분의 절연강도를 확인하기 위해 유중(油中)에서 상용주파 파괴전압시험을 하도록 규정하고 있다. 그러나 실제 전력계통에서 가장 많이 발생되는 과전압은 뇌임펄스전압이므로 이 임펄스전압으로 애자부분의 절연강도를 확인할 필요성이 있다. 그런데 ($1.2{\times}50$) ${\mu}s$의 표준뇌임펄스전압으로 시험하는 경우, 연면을 통한 섬락이 빨리 일어나게 되므로 날개부분의 절연강도를 확인하는 것이 어렵게 된다. 따라서 섬락전압을 가능한 한 높여서 날개부분의 관통파괴나 손상을 확인하기 위해 파두 준도가 큰 급준파를 시험전압으로 사용하는 것이다. 본 논문에서는 최대충전전압과 저장에너지가 비교적 낮은 임펄스전압시험장치를 가지고 급준파임펄스전압시험을 위한 회로 구성에 대해 고찰하였다.

• 프린팅코리아
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• v.8 no.8
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• pp.76-79
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• 2009

현재 전 세계적으로 수많은 제책 공정 기술이 쏟아져 나오고 있지만 일괄적인 방법을 통해 통일되기에는 한계가 있다. 이는 각 나라별로 출시하는 책의 두께 및 고객이 요구하는 방식이 다르기 때문이다. 또 종이의 크기나 콤프레셔 기술 등 작업 전반에 투입되는 요소들에 의해 많은 차이를 보인다. 이러한 제책 분야에서 작업 고정의 합리화를 추구하며 고객에게 맞춤형 기종을 선보이고 있는 업체가 있다. 표지날개 접지 재단기 전문 제작, 공급업체인 동우기계(대표 장석천)다.

• Journal of the Korea Convergence Society
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• v.11 no.10
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• pp.237-241
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• 2020

The flow analyses in this study were executed on the three washing machine models with the rotors like real shapes. On the pressures and speeds for the left, right and bottom planes of rotors, model C was generally found to have the greatest pressure on the flow, more than twice as much as model A, and in order of model B and model A. At the streamline velocities of flow on the side of the rotating blades of models A, B and C, model C had the greatest rate of flow overall, which was 1.7 times higher than model A, followed by model B and model A. In case of model C, the number of blades is smaller than model A or model B, but the thickness of lower rotor becomes thicker. It can be seen that model C improves the washing performance due to the high flow pressure and high flow rate. Also, it is seen that this study is adequate at the efficient design with durability of the washing machine rotor practically and the aesthetic convergence of the rotor.