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      • KCI등재

        Immediate Reconstruction of Large Ptotic Breasts following Vertical Reduction Pattern Nipple-Sparing Mastectomy

        정재호,황용재,정승필,박승하,윤을식 한국유방암학회 2021 Journal of breast cancer Vol.24 No.3

        Purpose: Women with large and/or ptotic breasts are generally not considered candidates for nipple-sparing mastectomy because of concerns regarding the high incidence of postoperative complications including ischemic complications. Therefore, we adopted a vertical skin resection technique for nipple-sparing mastectomy, and obtained satisfactory results following immediate autologous breast reconstruction. In this study, we aimed to describe our operative technique and review its outcomes. Methods: Between January 2010 and March 2017, immediate autologous breast reconstructions were performed in 28 patients with moderate or large ptotic breasts after nipple-sparing mastectomy using the vertical reduction pattern. Grade II ptosis was observed in 12 patients, and 16 patients were classified as having grade III ptosis. Results: Of the 28 patients, 21 received abdominal free flap reconstruction. In the remaining 7 patients, extended latissimus dorsi flaps were used in conjunction with anatomic implants. The mean weight of the excised breast tissue in the 2 groups was 575 g and 482 g, respectively. Satisfactory esthetic outcomes without major complications were achieved in all patients. Similar vertical reductions or mastopexies in the contralateral breast allowed better postoperative adjustment for symmetry. There was only 1 case of complete nipple necrosis; however, the problem was solved with “skin banking.” No local recurrences or distant metastases were detected at follow-up (mean 18 months, range 4 months to 6 years). Conclusion: To enhance cosmetic outcomes in patients with large and/or ptotic breasts, the vertical skin resection pattern for nipple-sparing mastectomy can be used to achieve better breast shape while preserving the nipple-areola complex. Moreover, it can improve the esthetic outcome without compromising oncologic safety.

      • KCI등재후보
      • 기업의 환위험 관리에 대한 문헌연구

        정재호,조혜진 한국국제금융학회 2011 국제금융연구 Vol.1 No.2

        This study attempts to introduce current literature on foreign exchange risk management by firms. This literature review centers on the following two fundamental questions. First, how do we define and measure foreign exchange exposure? Second, what factors influence foreign exchange exposure? In particular, we focus on previous literature on the effects of financial, operational, and pricing strategy on foreign exchange exposure. We also provide the future directions in this line of literature. 본 논문은 기업의 환위험 관리에 대한 문헌을 소개하는 것을 목적으로 한다. 이 문헌연구는 다음과 같은 두 가지 질문을 중심으로 이루어진다. 첫째, 환노출은 어떻게 정의되고 측정되는가? 둘째, 환노출에 영향을 미치는 요인들은 무엇인가? 특히, 환노출에 영향을 미치는 요인들 중 기업의 재무적 전략, 운영적 전략, 그리고 가격 책정 전략에 대한 연구들을 중점적으로 살펴본다. 본 논문은 기존의 연구에서 다루어지지 않은 향후 연구 방향도 소개한다.

      • KCI등재

        Optimization of thick wind turbine airfoils using a genetic algorithm

        정재호,김수현 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.7

        In this study, we optimized thick airfoils for wind turbines using a genetic algorithm (GA) coupled with computational fluid dynamics (CFD) and geometric parameterization based on the Akima curve fitting method. Complex and separated flow fields around the airfoils of each design generation were obtained by performing Reynolds-averaged Navier-Stokes steady flow simulation based on the in-house code of an implicit high-resolution upwind relaxation scheme for finite volume formulation. Airfoils with 40 % and 35 % thickness values were selected as baseline airfoils. An airfoil becomes thicker toward the blade root area, thereby increasing blade stiffness and lowering its aerodynamic efficiency. We optimized the airfoils to simultaneously maximize aerodynamic efficiency and blade thickness. The design variables and objective function correspond to the airfoil coordinates and the lift-to-drag ratio at a high angle of attack with airfoil thickness constraints. We improved the lift-to-drag ratio by 30 %~40 % compared with the baseline airfoils by performing optimization using GA and CFD. The improved airfoils are expected to achieve a 5 %~11 % higher torque coefficient while minimizing the thrust coefficient near the blade root area.

      • 자유무역협정하에서의 최적관세 소국과 대국의 경우

        정재호 한국조세연구원 2000 재정연구 Vol.7 No.1

        This present paper explores new external post-FTA tariffs between two asymmetric countries. This paper builds primarily from the Grossman-Helpman political economy framework and the earlier work of Martin Richardson. Adopting this setting, I show that a small country removes or reduces its external tariffs under an FTA. However, a large country always keeps positive optimal post-FTA tariffs and it might raise its tariffs against the rest of the world. In particular, when a country has lower tariff sectors than partners, a small country removes external tariffs because these tariffs create only consumption distortion. A large country, however, keeps its positive tariffs that improve its terms of trade and distort only consumption, not production. The terms of trade gain is always larger than the distortion loss, provided tariffs are non-prohibitive. Therefore, the large country might raise its tariffs against the rest of the world under the FTA. This result implies that a large country joining in FTA with a small country may have an incentive to violate GATT Article XXIV. Additionally, when a country has lower tariff sectors than a partners, both a large and a small country lower external tariffs to reduce the loss from partners free riding.

      • KCI등재

        Resection of Intrapericardial Schwannoma Co-Existing with Thymic Follicular Hyperplasia through Sternotomy without Cardiopulmonary Bypass

        정재호,김광택,이강훈,이승헌,이성호,정재승 대한흉부외과학회 2014 The Korean Journal of Thoracic and Cardiovascular Vol.47 No.3

        A 35-year-old man was admitted to Korea University Anam Hospital for evaluation of intermittent chest pain. Computed tomography of the chest showed enlargement of a previously identified anterior mediastinal mass and also a well-defined, circumscribed mass in the subcarinal area, surrounded by the roof of the left atrium, right pulmonary artery, and the carina. Complete resection of the intrapericardial tumor was performed through median sternotomy without cardiopulmonary bypass. Pathologic examination identified the tumor as schwannoma, of an ancient type, diffusely positive for the S-100 antigen. Unlike other reported cases, grossly, the tumor did not seem to be involved with any nerve.

      • KCI등재

        CFD investigation on the flatback airfoil effect of 10 MW wind turbine blade

        정재호,김수현 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.5

        The flatback airfoil effect on the inboard region of a large wind turbine blade was investigated by numerical analysis. Complicated flow phenomena in wind turbine blade with flatback and non-flatback airfoil were captured by Reynolds-averaged Navier–Stokes flow simulation with shear stress transport turbulence model. Although both airfoil blades were designed using blade element momentum theory to produce identical shaft power, results of three-dimensional computational fluid dynamics (CFD) flow analysis indicated that at a specific location of the root area, the flatback airfoil improved the inboard force by approximately 6 % compared with the non-flatback airfoil. We were also able to confirm that by using the flatback airfoil, the overall shaft power throughout the blade increased by 1 %, thereby restraining the bending moment exerted by the thrust force on the hub by 0.5 %. Moreover, numerical analysis results indicated that the flatback airfoil blade reduced the size of the secondary vortex around the blade root area and its progress in the secondary direction in comparison with the non-flatback airfoil blade. The shape of the flatback airfoil on the trailing edge weakened the adverse pressure gradient migrating from the lower to the upper surface. Regardless of the flatback airfoils, the tip vortex core of the outboard region formed on the suction surface leading edge and strongly rolled up by the pressure surface boundary layers due to the large pressure difference between the suction and pressure surfaces in the blade tip region. This remarkable strong tip vortex developed downstream and raked up the boundary layer of the blade trailing edge with low energy.

      • KCI등재
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