• Archives of Plastic Surgery
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• 제48권6호
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• pp.691-698
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• 2021

Background The reverse sural artery (RSA) flap is widely used for lower extremity reconstruction. However, patients sometimes suffer from donor site complications such as scar contracture and paresthesia, resulting in dissatisfaction with the aesthetic outcomes. This study investigated the characteristics of donor site morbidity associated with RSA flaps and described our experiences of dealing with complications by performing resurfacing surgery using thoracodorsal artery perforator (TDAP) flaps. Methods From April 2008 to August 2018, a total of 11 patients underwent contracture release and resurfacing surgery using TDAP flaps due to donor morbidity associated with RSA flaps. All affected donor sites were covered with a skin graft, the most common of which was a meshed split-thickness skin graft (six cases). Results Eight of the 11 patients (72.7%) suffered from pain and discomfort due to scar contracture, and seven (63.6%) complained of a depression scar. The donor sites were located 6.3±4.1 cm below the knee joint, and their average size was 140.1 cm². After resurfacing using TDAP flaps, significant improvements were found in the Lower Extremity Functional Scale (LEFS) scores and the active and passive ranges of motion (AROM and PROM) of the knee joint. The LEFS scores increased from 45.1 to 56.7 postoperatively (P=0.003), AROM increased from 108.2° to 118.6° (P=0.003), and PROM from 121.4° to 126.4° (P=0.021). Conclusions Planning of RSA flaps should take into account donor site morbidity. If complications occur at the donor site, resurfacing surgery using TDAP flaps achieves aesthetic and functional improvements.

• Geomechanics and Engineering
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• 제31권1호
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• pp.99-112
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• 2022

The present study examines the natural frequencies (NFs) of perfect/imperfect functionally graded sandwich beams (P/IP-FGSBs), which are composed of a porous core constructed of functionally graded materials (FGMs) and a homogenous isotropic metal and ceramic face sheets resting on elastic foundations. To accomplish this, the material properties of the FGSBs are assumed to vary continuously along the thickness direction as a function of the volume fraction of constituents expressed by the modified rule of the mixture, which includes porosity volume fraction represented using four distinct types of porosity distribution models. Additionally, to characterize the reaction of the two-parameter elastic foundation to the Perfect/Imperfect (P/IP) FGSBs, the medium is assumed to be linear, homogeneous, and isotropic, and it is described using the Winkler-Pasternak model. Furthermore, the kinematic relationship of the P/IP-FGSBs resting on the Winkler-Pasternak elastic foundations (WPEFs) is described using trigonometric shear deformation theory (TrSDT), and the equations of motion are constructed using Hamilton's principle. A closed-form solution is developed for the free vibration analysis of P/IP-FGSBs resting on the WPEFs under four distinct boundary conditions (BCs). To validate the new formulation, extensive comparisons with existing data are made. A detailed investigation is carried out for the effects of the foundation coefficients, mode numbers (MNs), porosity volume fraction, power-law index, span to depth ratio, porosity distribution patterns (PDPs), skin core skin thickness ratios (SCSTR), and BCs on the values of the NFs of the P/IP-FGSBs.

• Computers and Concrete
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• 제33권1호
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• pp.27-39
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• 2024

In this study, the authors investigate the free vibration behavior of three-phases functionally graded sandwich plates using a novel nth-order shear deformation theory. These plates are composed of a homogeneous core and two face-sheet layers made of different functionally graded materials. This is the novel type of the sandwich structures that can be applied in many fields of mechanical engineering and industrial. The proposed theory only requires four unknown displacement functions, and the transverse displacement does not need to be separated into bending and shear parts, simplifying the theory. One noteworthy feature of the proposed theory is its ability to capture the parabolic distribution of transverse shear strains and stresses throughout the plate's thickness while ensuring zero values on the two free surfaces. By eliminating the need for shear correction factors, the theory further enhances computational efficiency. Equations of motion are established using Hamilton's principle and solved via Navier's solution. The accuracy and efficiency of the proposed theory are verified by comparing results with available solutions. The authors then use the proposed theory to investigate the free vibration characteristics of three-phases functionally graded sandwich plates, considering the effects of parameters such as aspect ratio, side-to-thickness ratio, skin-core-skin thicknesses, and power-law indexes. Through careful analysis of the free vibration behavior of three-phases functionally graded sandwich plates, the work highlighted the significant roles played by individual material ingredients in influencing their frequencies.

• Archives of Reconstructive Microsurgery
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• 제21권2호
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• pp.143-148
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• 2012

Purpose: This report presents the authors' experience of twelve patients with sural artery flap for soft tissue defects around the knee joint. Materials and Methods: The patients' age ranged from 25 to 80 years; seven of the patients were male and five were female. The cause of soft-tissue defects involved wide excision for malignant soft tissue tumor, tumor prosthesis related infection, infection after total knee arthroplasty and chronic osteomyelitis. Postoperative range of motion was checked. The sensibility of flap was evaluated by Semmes-Weinstein monofilaments and two-point discrimination. Results: All flaps survived and provided satisfactory coverage of the defect. There was no complication except one delayed skin graft incorporation at donor site. Seven knee joints which had been stiff previously gained average 58 degrees of ROM postoperatively. All flaps retained sensibility and showed no significant increase in sensory thresholds comparing with contralateral side. Conclusion: Sural artery flap not only shows high survival rate and broad coverage ability, but also offers improvement in range of motion and preservation of sensation. We speculate that sural artery flap is valuable for the reconstruction of the soft tissue defects around knee joint.

• Archives of Reconstructive Microsurgery
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• 제10권2호
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• pp.93-98
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• 2001

Purpose : This describes our experience with a tenocutaneous free flap from the dorsum of the foot or radial forearm to reconstruct the dorsal skin and extensor tendons of the hand. Material and Methods : Between february 1987 and July 1998, we treated 9 patients with composite tissue loss on the dorsal hand caused by crushing injury. Nine men had an average age of 26.4 years(range, $19{\sim}47$). We treated 5 patients with the free dorsalis pedis flap including the extensor tendons and the superficial peroneal nerve and 4 patients with reverse forearm flap including the brachioradialis tendon and/or superficial radial nerve. Flap size was average 4.4(3,2cm. Evaluation of the results was based on the survived flap rate, the recovery rates for range of motion of the metacarpophalageal joints in the operated fingers. two-point discrimination. Results : All flaps were well vascularized and survived completely. Recovery rates for range of motion of the metacarpophalageal joints in operated fingers range from $78%{\sim}99%$(average, 90%). Two-point discrimination of the transferred flaps in 5 patients average $20{\pm}3.5mm$. Conclusion : The advantages of this procedure are mass action reconstruction with tendon, one-stage operation, faster healing with less adhesion formation, and early mobilization.

• Archives of Reconstructive Microsurgery
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• 제21권1호
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• pp.21-26
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• 2012

The radial artery superficial palmar branch free flap is based on the perforators of the superficial palmar branch of the radial artery and its venae comitantes. This flap can be used as a sensible flap including palmar cutaneous branch of the median nerve. Forty radial artery superficial palmar branch free flaps were performed at Centum Institute during October 2010 to December 2011. There were 32 males and 8 females and their mean age were 48 years (range 30 to 66 years). The thumb injured in 13 patients, the index finger in 16 patients, the middle finger in 4 patients, the ring finger in 2 patients, and the little finger in 5 patients. The mean size of the flap was $2.5{\times}3.5$ cm(range $2{\times}2.5$ to $3{\times}7$ cm). The donor site was always closed primarily. The overall survival rate was 90.2 percent. The flaps showed well-padded tissue with glabrous skin. All patients have touch sensation and showed 12 mm two point discrimination in an average(range 8 to 15 mm). Donor site morbidity was conspicuous. One patient showed unsightly scar. Early postoperative range of motion of the affected thumb showed slightly limited radial and palmar abduction. But it improved after postoperative 2 months, and patients did not complaint limitation of motion. In conclusion, the radial artery superficial palmar branch free flap can be used as an option for soft tissue reconstruction of finger defects where local or island flaps are unsuitable.

• 대한기계학회논문집B
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• 제41권7호
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• pp.463-468
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• 2017

경피를 통한 약물 전달 방식에 있어, 본 연구에서 제안하고 있는 바늘 없는 주사기 시스템은 레이저와 마이크로젯 인젝터로 구성 되어 있다. 이때 마이크로젯 인젝터의 핵심 메커니즘은 레이저 유도버블이다. 동력원으로 Nd:YAG와 Er:YAG, 두 종류의 레이저가 사용되었다. 버블의 특성을 결정짓는 레이저 변수인 펄스폭, 파장 등이 본 연구에서 고려되었다. Nd:YAG 레이저의 경우에 펄스폭이 버블의 생존 시간보다 짧기 때문에 캐비테이션에 가까운 버블을 형성하는 반면 Er:YAG 레이저의 경우에 펄스폭이 상대적으로 길고 물에서의 흡수가 잘 되기 때문에 보일링 버블이 만들게 된다. 버블 및 마이크로젯의 자세한 움직임은 초고속 카메라를 통해 촬영되었다. 이와 같은 과정을 통하여 마이크로젯의 특성이 버블에 의해 결정되는 것을 본 연구를 통해 관찰되었다. 약물 전달 성능은 기니어피그 조직에 형광물질을 침투한 결과로 부터 분석하였다.

• 한국산업정보학회논문지
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• 제13권4호
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• pp.145-154
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• 2008

본 논문에서는 애완용 로봇에 장착된 카메라로부터 획득된 연속 영상에서 사용자의 손 제스처를 인식하여 로봇을 제어하는 시스템을 제안한다. 제안된 시스템은 손 검출, 특징 추출, 제스처 인식 로봇 제어의 4단계로 구성된다. 먼저 카메라로부터 입력된 영상에서 HSI 색상공간에 정의된 피부색 모델과 연결성분 분석을 이용하여 손 영역을 검출한다. 다음은 연속 영상에서 손 영역의 모양과 움직임에 따른 특징을 추출한다. 이때 의미 있는 제스처의 구분을 위해 손의 모양을 고려한다. 그 후에 손의 움직임에 의해 양자화된 심볼들을 입력으로 하는 은닉 마르코프 모델을 이용하여 손 제스처는 인식된다. 마지막으로 인식된 제스처에 대응하는 명령에 따라 애완용 로봇이 동작하게 된다. 애완용 로봇을 제어하기 위한 명령으로 앉아, 일어서, 엎드려, 악수 등의 제스처를 정의하였다. 실험결과로 제안한 시스템을 이용하여 사용자가 제스처로 애완용 로봇을 제어 할 수 있음을 보였다.

• Archives of Reconstructive Microsurgery
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• 제12권1호
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• pp.38-43
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• 2003

Purpose : Various free flaps and pedicled island flaps are effective for reconstruction of soft tissue defect developed after tumor excision. We want to know the advantage of dorsalis pedis island flap for reconstruction of soft tissue defect caused by soft tissue tumor excision. Materials and Methods : Between 1992 and 2002, we performed 4 dorsalis pedis island flap procedure for reconstruction of soft tissue defect of lower limb developed after soft tissue tumor excision. Average age was 54.7 years old $(40{\sim}68)$, and male 2 cases, female 2 cases. The kinds and number of soft tissue tumors were 2 squamous cell carcinoma and 2 malignant melanoma. The procedures that we performed were all dorsalis pedis island flap. The analysis for the result of treatment was retrospectively accessed by physical examination and questionnaire for whether the change of symptom after operation, range of adjacent joint motion. Also we reviewed associated complication after operative treatment. Results : All dorsalis pedis island flaps were alive. There is no problem for activity of daily living, no skin necrosis and no limitation of motion of adjacent joint. In 1 case of them, the patients died of distant metastasis. Conclusion: Dorsalis pedis island flap procedure as a pedicled island flap procedure is very effective and easy operative procedure for reconstruction of soft tissue defect of lower limb developed after tumor excision compared to free flap procedure because there is no need for microvascular surgery, we can obtain relatively large flap and the lesion and flap donor site locate in the same limb.

• 대한전자공학회논문지SP
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• 제38권6호
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• pp.684-691
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• 2001

본 논문에서는 비디오 카메라를 통하여 획득한 연속적인 영상에서 사람의 머리를 인식하고 추적하는 시스템을 구현한다. 사람의 머리를 인식하기 위한 특징 벡터로서 얼굴 표면상의 특성인 사람의 피부색과 형태상의 특성인 타원 모델링을 이용한다. 또한 복잡한 배경으로부터 움직인 영역을 획득하기 위하여 시변 에지 검출 방법을 사용하고 획득된 영상에서 물체의 움직임을 판별하기 위하여 수직 투영 방법을 이용한다. 설정된 움직임 영역부분에 대하여 피부색을 갖고 있는 여러 개의 얼굴 후보영역을 설정하고 사람의 얼굴을 대표할 수 있는 타원 매핑을 적용하여 가장 최적으로 매핑되는 영역을 사람의 얼굴 부분으로 인식한다. 본 논문에서 제안한 방법은 사람 얼굴이 360도 회전하는 경우와 부분적으로 가려진 경우 그리고 좌우로 기울어진 경우에서도 우수한 성능을 보여주고 있다. 본 논문에서는 움직임 기반 추적 방법과 인식 기반 추적 방법을 이용하여 사람의 얼굴 부분이 빠르게 움직이는 경우에도 정확한 사람 얼굴 추적이 가능하도록 한다.