• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.236-241
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• 2011

An active trailing-edge flap blade named as Seoul National University Flap (SNUF) blade is designed for reducing helicopter vibratory loads and the relevant aeroacoustic noise. Unlike the conventional rotor control, which is restricted to 1/rev frequency, an active control device like the present trailing-edge flap is capable of actuating each individual blade at higher harmonic frequencies i.e., higher harmonic control (HHC) of rotor. The proposed blade is a small scale blade and rotates at higher RPM. The flap actuation components are located inside the blade and additional structures are included for reinforcement. Initially, the blade cross-section design is determined. The aerodynamic loads are predicted using a comprehensive rotorcraft analysis code. The structural integrity of the active blade is verified using a stress-strain recovery analysis.

• 한국전산유체공학회:학술대회논문집
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• 2008.03a
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• pp.227-228
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• 2008

In the present paper, fowler flap was optimized to maximize the lift with response surface method. Leading edge shape and the gap between main airfoil and flap, were optimized and the aerodynamic characteristics was improved considerably. The optimized flap has more rounded leading edge and bigger gap. Before angle of attack, $10^{\circ}$, lift and drag are improved and the optimized flap shows similar aerodynamic characteristics to the original flap. The flow condition for optimization was angle of attack, $10^{\circ}$, Mach number, 0.2, flap deflection, $40^{\circ}$.

• 한국전산유체공학회:학술대회논문집
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• 2008.10a
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• pp.227-228
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• 2008

In the present paper, fowler flap was optimized to maximize the lift with response surface method. Leading edge shape and the gap between main airfoil and flap, were optimized and the aerodynamic characteristics was improved considerably. The optimized flap has more rounded leading edge and bigger gap. Before angle of attack, $10^{\circ}$, lift and drag are improved and the optimized flap shows similar aerodynamic characteristics to the original flap. The flow condition for optimization was angle of attack, $10^{\circ}$, Mach number, 0.2, flap deflection, $40^{\circ}$.

• Korean Journal of Computational Design and Engineering
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• v.9 no.3
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• pp.253-259
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• 2004

A numerical investigation was performed to determine the effect of airfoil on the optimum flap height using NACA0015 Wells turbine. The five double flaps which have 0.5% difference were selected. A Navier-Stokes code, CFX-TASCflow, was used to calculate the flow field of the Wells turbine. The basic feature of the Wells turbine is that even though the cyclic airflow produces oscillating axial forces on the airfoil blades, the tangential force on the rotor is always in the same direction. Geometry used to define the three dimension numerical grid is based upon that of an experimental test rig. This paper tries In optimized disign the double flap of Wells turbine with the numerical analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.1
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• pp.11-19
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• 2005

In order to improve dynamic stall characteristics of an oscillating airfoil, optimal design has been performed for fixed nose droop and Gurney flap. Fixed nose droop is known to be very effective to improve pitching moment characteristics but may cause degeneration of aerodynamic lift at the same time. On the other hand, Gurney flap has the opposite characteristics. For fixed nose droop, location and angle are chosen as design variables, while length is defined as design variable for Gurney flap. Higher order response surface methodology and sensitivity based optimal design method are employed to handle highly nonlinear problem such as dynamic stall. Optimal design has been performed so that lift and pitching moment are simultaneously improved. The design results show that aerodynamic characteristics can be remarkably improved through present design approach and the present passive control method is as good as active control method which combines variable nose droop and Gurney flap.

• Archives of Plastic Surgery
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• v.47 no.6
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• pp.535-541
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• 2020

The keystone design perforator island flap can be utilized in the repair of trunk defects. A systematic review was carried out to identify the complication rates of the use of this flap to treat such defects. The MEDLINE, Embase, Cochrane Library, and PubMed Central databases were searched for articles published between January 2003 and December 2018 that reported the use of keystone design perforator island flaps in the repair of trunk defects. Study selection was conducted in alignment with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Eight articles involving a total of 54 flaps satisfied the inclusion criteria. The most frequently reported cause of trunk defects was oncologic resection (64.4%). The overall complication rate was 35.2%, and complications included infection (11.1%), wound dehiscence (7.4%), delayed healing (7.4%), and partial flap loss (1.9%). The keystone design perforator island flap is associated with a high success rate and low technical complexity. Despite minor complications, keystone design flaps could be a preferred choice for trunk reconstruction.

• Archives of Reconstructive Microsurgery
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• v.25 no.2
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• pp.72-74
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• 2016

The keystone flap is a fascia-based island flap with two conjoined V-Y flaps. Here, we report a case of successful treatment of a trochanter pressure sore patient with the traditional keystone flap. A 50-year-old male patient visited our department with a $3{\times}5cm$ pressure sore (grade III) to the left of the greater trochanter that was covered with eschar. Debridement was done and the defect size increased to $5{\times}8cm$ in an elliptical shape. Doppler ultrasound was then used to locate the inferior gluteal artery perforator near the wound. The keystone flap was designed to the medial side. The perforator based keystone island flap covered the defect without resistance. The site remained clean, and no dehiscence, infection, hematoma, or seroma developed. In general, greater trochanter pressure sores are covered with a perforator based propeller flap or fascia lata flap. However, these flaps have the risk of pedicle kinking and require a large operation site. For the first time, we successfully applied the keystone flap to treat a greater trochanter pressure sore patient. Our design was also favorable with the relaxation skin tension lines. We conclude that the keystone flap including a perforator is a reliable option to reconstruct trochanteric pressure sores.

• Archives of Reconstructive Microsurgery
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• v.19 no.1
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• pp.56-60
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• 2010

Purpose: Breast reconstruction with abdominal flap has many advantages. However, it might cause abdominal complications such as bulging or hernia. SIEA (Superficial inferior epigastric artery) flap is the most advanced form of abdominal flap which has no adverse effect on abdominal fascia. We report 2 cases of breast reconstruction with SIEA flap with reference review. Methods: From Jun 2006 to Jan 2009, 110 patients underwent breast reconstruction with free abdominal flap. We tried to find the SIEA in every cases and adopted SIEP flap if the diameter was larger than 1mm and it had visible pulsation. 2 patients underwent breast reconstruction with SIEA flap. After design of abdominal flap SIEA was investigated with portable Doppler. SIEA was usually found 4-5 cm lateral to the midline. Flap was elevated with SIEA and SIEV to their maximal length at hiatus. Results: There were no complications, such as infection, hematoma, and necrosis of flap. In both cases, flaps survived completely with excellent vascularity and breast reconstruction was successful. In one case, there was skin necrosis of mastectomy flap, and it was healed by conservative management. Conclusion: With the SIEA flap, donor site morbidity can be minimized along with reduction of operation time. If there is reliable SIEA, SIEA flap would be the preferred skills. However, the limitation of the SIEA flap is difficulty in identifying the SIEA. The reason for less availability of the flap in Korea might include high prevalence of the Caesarian section scar and relatively higher level of the lower margin of the flap.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.1
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• pp.70-74
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• 2004

Model tests for a stern flap have been performed to decrease the resistance of a large warship and to optimize the flap. Stern flaps and wedges of fast crafts are studied to apply to a large vessel in terms of speed-length ratio. The model tests of the flap has been carried out to find the effects of the design parameters, i.e. length and angie on resistance decrease. This work concludes that the optimized stern flap reduced resistance not only at the high speed by 9％ but also at the cruising speed.

• Archives of Reconstructive Microsurgery
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• v.26 no.1
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• pp.14-17
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• 2017

The superior gluteal artery perforator flap technique has increasingly been used for soft tissue defects in the sacral area following its introduction nearly 25 years ago. Advantages in covering sacral defects include muscle sparing, versatility in design, and low donor side morbidity. The bilateral superior gluteal artery perforator flap procedure is planned in cases of large sacral defects that cannot be covered with the unilateral superior gluteal artery perforator flap. Here, we report two cases of large sacral defects in which patient factors of poor general health, such as old age, pneumonia, and previous operation scar, led to use of a large unilateral superior gluteal artery perforator super-flap with parasacral perforator. The approach was utilized to reduce the operation time and prevent unpredictable flap failure due to the large flap size. Even though the parasacral perforator was included, the versatility of the large superior gluteal artery perforator flap was preserved because sufficient perforator length was acquired after adequate dissection.