• Archives of Plastic Surgery
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• v.49 no.6
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• pp.724-728
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• 2022

Various flaps are used to reconstruct skin and soft tissue defects of the vulva following resection of malignancies. Whenever possible, reconstruction using local flaps is the standard treatment. Here, we describe vulvar defect reconstruction using keystone flaps. Standard keystone flaps are based on randomly located vascular perforators. However, we designed a keystone flap that includes perforators of three named arteries (the anterior labial artery of the external pudendal artery, cutaneous branches of the obturator artery, and posterior labial artery of the internal pudendal artery) and the pudendal nerve, which accompanies the internal pudendal artery. Four patients with squamous cell carcinoma and extramammary Paget's disease of the vulva underwent radical vulvectomy and keystone flaps including perforators of three arteries. Depending on the morphology of the defects, keystone flaps were used with different designs. For elliptical and unilateral vulvar defects, a standard keystone flap was designed, and for defects on both sides of the vulva, a double opposing keystone flap was used. For oval defects, the omega variant keystone flap was designed, and when the morphology of the defect needed rotation of the flap, a rotational keystone flap was designed. All the patients showed good function and sensation, with an acceptable cosmetic appearance.

• 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.

• Geotechnical Engineering
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• v.14 no.3
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• pp.109-122
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• 1998

In the design and construction of Keystone block reinforced wall with geogrid, previous on the behaviour of wall in curved area is required. This study is to investigate the structural stability of wall and problems during construction in curved area. Previous analyzing methods, usually used for straight area of wall, have been reviewed to find any problems in applying to stability analysis of curved area. Thus, the purpose of this study is to show how to analyse the straight area of Keystone block wall first, and then turn this to use for analyzing various significance, concerning the design or construction of curved high keystone block wall. and the stress behavior on retaining wall between straight and curved conditions by F.E.M, using the shell analysis theory.

• Bulletin of Food Technology
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• v.23 no.1
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• pp.148-152
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• 2010

• Archives of Plastic Surgery
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• v.48 no.3
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• pp.261-268
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• 2021

Background Various methods have been described to close large meningomyelocele defects, but no technique has been proven superior to others. This study presents cases of meningomyelocele defect closure with a keystone-design perforator island flap. Methods A retrospective study was performed on 14 patients with meningomyelocele defects closed using various types of keystone flaps. Results The median age of the patients at surgery was 10.5 days (range, 1-369 days) and the average defect size was 22.5 cm² (range, 7.1-55.0 cm²). The average operative time for defect closure was 89.6 minutes (range, 45-120 minutes). Type IV bilateral keystone flaps were used for four defects, type IV unilateral flaps for six defects, type IIA flaps for two defects, and type III flaps for two defects. Conclusions All the defects healed completely with no major complications. The keystone-design perforator island flap is a reliable, easy, and fast technique to close large meningomyelocele defects.

• Archives of Plastic Surgery
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• v.48 no.3
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• pp.254-260
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• 2021

Background Myelomeningocele is a frequently seen condition at tertiary care hospitals. Its treatment involves a variety of plastic reconstructive techniques. Herein, we present a series of myelomeningocele patients treated using keystone flaps. Methods We gathered information regarding soft tissue reconstruction and the use of bilateral keystone flaps to treat myelomeningocele patients. We obtained data from clinical records and recorded the demographic characteristics of mothers and children with the condition. The size, level of defect, and complications detected during the follow-up were analyzed. Results A series of seven patients who underwent bilateral keystone flaps for myelomeningocele closure was analyzed. There were no cases of midline or major dehiscence, flap loss, necrosis, surgical site infections, or cerebrospinal fluid leakage. No revision procedures were performed. Minor complications included one case with minimal seroma and three cases with areas of peripheral dehiscence that healed easily using conventional measures. Conclusions The use of keystone flaps is an adequate option for closure of dorsal midline soft tissue defects related to myelomeningocele. This technique offers predictable results with an acceptable spectrum of complications. Robust blood flow can be predicted based upon anatomical knowledge.

• Proceedings of the Korea Contents Association Conference
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• 2006.11a
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• pp.524-527
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• 2006

This paper discusses a method to efficiently remove the keystone distortion in images. The keystone distortion which generated during 2D image aquisition to realize 3D stereoscopic images is removed by the bilinear interpolation method. Usually, the keystone distortion in 2D images can remove by the optical equipment but the image processing is more effective than the optical equipment in consideration of efficiency or simplicity of the works. This method can be realized 3D stereoscopic image without the distortion.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.4
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• pp.24-36
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• 2008

The essence of a natural stream restoration project is providing habitats for various creatures in terms of the stream's environmental function. This research suggests the problems of natural stream restoration project by studying streams in terms of habitats for creatures and reviewing the national and international cases on existing natural stream restoration project. As a solution for the above, this research suggests a preservation method for biotope of upper stream areas focusing on the fish biotope area considering the ecological characteristics and preservation value of the respective stream so that the stream can be preserved as habitats for creatures. The research was carried out on Cheonglimli Baekcheon region which is an upper stream area of Buan-Dam located in the public park in Byunsanbando, Buangoon, Jeonlabookdo. We suggest the preservation method based on the habitat environment and keystone species of fish. The habitat environment evaluation was carried out mainly being divided into three groups namely, habitats and surrounding environment, reservoir's features and fish way and the diversity of fish. By improving the problematic elements discovered through such evaluation, it tries to improve the biotope of the stream and continuously preserve the stream. In addition, in order to restore the stream as habitats for various creatures, this research suggests to select keystone species which are suitable for the stream environment and restore the habitats based on the keystone species rather than restoring habitats for all species. Fish not only plays the role of a consumer of Epilithic algae and water beetles but also plays an important ecological role as a food for birds or small mammalia. If such ecologically important biotope for fish is preserved, the ecological environment of the stream will be maintained more stably.

• 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.

• International Journal of Railway
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• v.9 no.1
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• pp.15-20
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• 2016

An approach section on an abutment is located between the soil embankment and the structure, which may cause an uneven surface due to different settlement between the abutment and the soil embankment. This study proposes a new type of wall which separates the abutment from the backfill material using mechanically stabilized wall. A new type of keystone which incorporates geotube and wire mesh is proposed and evaluated. Numerical analyses were performed to investigate the applicability of the proposed keystone type, which incorporates Geosynthetic. The maximum horizontal displacements along GRS wall faces, settlements at the top of pavement and track bed, and tensile forces applied on geotextiles under traffic loads were investigated. The results of the numerical analysis showed that the proposed wall can be used for highway and high-speed railway abutment.