• 대한조선학회논문집
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• 제60권4호
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• pp.231-239
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• 2023

In order to improve the propeller Cavitation Inception Speed (CIS) performance, it needs to modify the propeller geometry and the wake distribution that flows into the propeller. In the previous study, the twisted angles of the V-strut were modified to improve propeller CIS, cavitation behavior and pressure fluctuation performances. Then the propeller behind the modified V-strut (New strut) showed better cavitation characteristics than that behind the existing V-strut (Old strut). However, the CIS of Suction Side Tip Vortex (SSTV) and Pressure Side Tp Vortex (PSTV) showed a big difference at behind each V-strut. In this study, the balance design is conducted to minimize the difference between SSTV CIS and PSTV CIS at behind each V-strut. To improve the propeller CIS performance, 1 propeller is designed at behind the old strut and 3 propellers are designed at behind the new strut. The propeller CIS is increased through the balance design and the stern appendage modification. The final propeller CIS is increased about 5.3 knots higher than that of the existing propeller at behind the old strut. On the basis of the present study, it is thought that the better improvement method for the propeller CIS would be suggested.

• 대한조선학회논문집
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• 제60권1호
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• pp.1-9
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• 2023

In order to improve the propeller cavitation performance composed of Cavitation Inception Speed (CIS), cavitation extent and pressure fluctuation, it needs to improve the wake distribution that flows into the propeller. The warship propeller cavitation is strongly influenced by the wake created at the V-strut of various appendages. The inflow characteristics of the V-strut were investigated using Computational Fluid Dynamics (CFD) and the twisted angles of the V-strut were aligned with upstream flow. The resistance and self-propulsion tests for the model ship with the existing and modified V-struts were conducted in Towing Tank (TT), and wake distribution, CIS, cavitation observation and pressure fluctuation tests were conducted in Large Cavitation Tunnel (LCT). The propeller behind the modified V-strut showed better cavitation characteristics than that behind the existing V-strut. Another model test was conducted to investigate rudder cavitation performance by the change of the V-strut. The rudder cavitation characteristics were not improved by the change of the operating conditions. On the basis of the present study, it is thought that the stern appendages for better propeller cavitation performance would be developed.

• 한국구조물진단유지관리공학회 논문집
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• 제14권3호
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• pp.123-130
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• 2010

본 논문에서는 기존 건축물의 내진성능을 향상시키기 위해 시공성과 설치 비용적인 측면에서 상대적으로 우수한 강재댐퍼를 대상으로 기존 개발된 장치와 새로 개발된 형상의 장치에 대한 평가를 해석적으로 수행하였다. 해석결과는 강도 및 에너지 소산능력으로 평가하였으며, 제안된 내력 산정식의 적용을 아울러 평가하였다. 연구대상 댐퍼의 스트럿 형상은 V형, S형이며, 댐퍼의 스트럿 높이와 각도를 주요 변수로 한 후 ABAQUS를 이용하여 유한요소 해석하였다. 해석은 최대변위를 50mm로 하고 점진적인 이력변위곡선을 적용하여 수행하였다. 항복강도, 최대강도, 에너지 소산능력 평가결과, V형 및 S형 모두 우수한 성능을 보유한 것으로 평가되었으며, 또한 스트럿 각도 $60^{\circ}$ 및 높이 140, 200 mm의 성능이 안정적인 것으로 평가되었다. 전체적으로는 S형의 응답이 V형보다 안정적인 것으로 평가되어, S형 강재댐퍼의 적용성이 V형보다 유리한 것으로 평가되었다.

• 한국구조물진단유지관리공학회 논문집
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• 제15권1호
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• pp.254-262
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• 2011

본 연구의 목적은 슬릿형 강재댐퍼보다 에너지 소산능력 등이 우수할 것으로 예상되는 V형 강재 댐퍼 개발에 있다. 이를 위하여 댐퍼 스트럿의 높이 및 각도에 대한 실험체 9개를 만들어 전단실험을 수행하였다. 실험결과, 스트럿 높이가 270mm이고, 스트럿 각도 $60^{\circ}$인 경우의 V형 강재댐퍼가 가장 우수한 내진성능 보유한 것으로 평가되었다. 또한 기존내력식을 이용한 댐퍼의 항복강도를 비교한 결과, 기존 실험결과를 분석한 범위 내에서 V형 댐퍼의 실험결과가 높게 평가되는 것으로 나타났다.

• 대한조선학회논문집
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• 제33권1호
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• pp.27-39
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• 1996

잠수체(strut)에 부착된 핀(fin)의 자유표면 효과를 회류수조를 사용하여 실험적으로 연구하였다. 본 연구에서는 주로 유속(V), 핀의 앙각(${\alpha}$)과 핀의 몰수깊이 대 현장비, 즉 몰수비(H/C)에 따른 핀의 양력을 축정하였으며, 지주가 없는 핀만의 양력을 측정하여 지주에 부착된 핀의 양력과 비교함으로써 핀에 미치는 지주의 영향도 관찰하였다. 유동가시화를 통하여 지주만 있을 때와 핀이 부착되어 있을 때의 앙각에 따른 자유표면의 변화를 조사하였다. 이와 같은 실험들은 대체로 몰수비가 작은 영역을 중심으로 수행되었다. 본 연구의 결과로는 핀의 양력계수(CL)는 작은 몰수비(H/C<3.0)의 경우 자유표면의 영향을 크게 받으며, 큰 몰수비(H/C>5.0)인 경우는 자유표면의 영향을 거의 무시할 수 있다. 작은 몰수깊이에서 핀의 유입앙각도 지주와 유속에 의해 크게 영향을 받는다. 자유표면의 변형은 지주에 의한 조파현상이 지배적인 역할을 하고 있으나 핀의 몰수깊이가 작을 경우는 핀의 영향도 크게 작용한다.

• Archives of Plastic Surgery
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• 제43권5호
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• pp.424-429
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• 2016

Background The objective of this paper was to describe a novel technique for improving the maintenance of nipple projection in primary nipple reconstruction by using acellular dermal matrix as a strut in one of three different configurations, according to the method of prior breast reconstruction. The struts were designed to best fill the different types of dead spaces in nipple reconstruction depending on the breast reconstruction method. Methods A total of 50 primary nipple reconstructions were performed between May 2012 and May 2015. The prior breast reconstruction methods were latissimus dorsi (LD) flap (28 cases), transverse rectus abdominis myocutaneous (TRAM) flap (10 cases), or tissue expander/implant (12 cases). The nipple reconstruction technique involved the use of local flaps, including the C-V flap or star flap. A $1{\times}2-cm$ acellular dermal matrix was placed into the core with O-, I-, and L-shaped struts for prior LD, TRAM, and expander/implant methods, respectively. The projection of the reconstructed nipple was measured at the time of surgery and at 3, 6, and 9 months postoperatively. Results The nine-month average maintenance of nipple projection was $73.0%{\pm}9.67%$ for the LD flap group using an O-strut, $72.0%{\pm}11.53%$ for the TRAM flap group using an I-strut, and $69.0%{\pm}10.82%$ for the tissue expander/implant group using an L-strut. There were no cases of infection, wound dehiscence, or flap necrosis. Conclusions The application of an acellular dermal matrix with a different kind of strut for each of 3 breast reconstruction methods is an effective addition to current techniques for improving the maintenance of long-term projection in primary nipple reconstruction.

• 한국산학기술학회논문지
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• 제15권4호
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• pp.2406-2413
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• 2014

깊은 보는 지간-높이 비가 중요한 파라미터이다. 깊은 보를 설계할 때, ACI 318-02 이후 버전에서는 응력의 비선형 분포로 인해서 고전적인 설계 방법이 아니라 스트럿-타이 모델을 부록에 수록하여, 이 방법으로 설계하도록 하고 있다. 본 연구에서는 ACI 고전적인 설계방법과 스트럿-타이 모델을 비교, 분석하였다. 파라미터 연구로 지간-높이 비를 변화시켰으며, 총 68개의 샘플을 분석하였다. 결과로 고전적인 설계 방법과 스트럿-타이 모델은 빔의 지간-높이 비에 따라서 각각 장단점이 있으며, 본 논문에 깊은 보를 설계할 때의 팁이 제시되어 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 Techno-Fair 및 합동춘계학술대회 논문집 전기물성,응용부문
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• pp.189-190
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• 2008

This study was investigated a possibility of fault of glass insulator due to vibration on high-speed railway. The proper vibration of 1-glass insulator have many frequency band and high amplitude showed in high frequency than low frequency. The proper vibration of strut tube insulator was lowest 170Hz, highest 1.5kHz. The field signal amplitude of viaduct and open route were biggest moment pantograph of high-speed rail. The surface vibration(V3) amplitude of strut tube insulator was biggest. From the FFT analysis of viaduct and open route, the strut tube insulator effect by vertical vibration was big, the frequency was 82.5Hz and 105Hz, respectively. However, in comparison with the proper vibration of strut tube insulator, the resonance was not observed. Although the amplitude of insulator is high, the possibility of fault is low because the glass insulator deterioration by the accumulation of vibration do not happen.

• Structural Engineering and Mechanics
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• 제73권5호
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• pp.515-527
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• 2020

This paper presents a stress field approach for the shear capacity of stirrup-reinforced concrete beams that explicitly incorporates the contribution of principal tensile stresses in concrete. This formulation represents an extension of the variable strut inclination method adopted in the Eurocode 2. In this model, the stress fields in web concrete consist of principal compressive stresses inclined at an angle θ combined with principal tensile stresses oriented along a direction orthogonal to the former (the latter being typically neglected in other formulations). Three different failure mechanisms are identified, from which the strut inclination angle and the corresponding shear strength are determined through equilibrium principles and the static theorem of limit analysis, similar to the EC-2 approach. It is demonstrated that incorporating the contribution of principal tensile stresses of concrete slightly increases the ultimate inclination angle of the compression struts as well as the shear capacity of reinforced concrete beams. The proposed stress field approach improves the prediction of the shear strength in comparison with the Eurocode 2 model, in terms of both accuracy (mean) and precision (CoV), as demonstrated by a broad comparison with more than 200 published experimental results from the literature.

• 복합신소재구조학회 논문집
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• 제4권2호
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• pp.8-14
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• 2013

Deep beam shall be designed either by taking into account nonlinear distribution of strain or by Appendix A of Strut-and-Tie Models (STM) according to ACI 318(M) from version of 2002. Although STM is accepted as tool in design Discontinuity region (D-region) which mostly exist in Deep beam, Corbels, Dapped ends etc., it has been modified by many researchers. In this study we design deep beam by STMs which use simple truss for load distribution and the model of complex truss for load distribution compare with the ACI traditional which is designed by flexure design method and shear provided by concrete($V_c$) as provided in special provisions section of 11.8 in ACI 318-99 [1]. This study aims to find the different and efficiency of deep beam design based on variation of parameter compiled from many samples selected from ACI traditional and two model of STMs, simple and complex load distribution.