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波形壁 流路내에서 凝縮이 수반되는 超音速유동에 대한 硏究
권순범,김병지,김흥균 대한기계학회 1994 대한기계학회논문집 Vol.18 No.2
The characteristics of supersonic flow with condensation along a wavy wall of a small Smplitude in a channel is investigated experimentally and numerically. In the present study for the case of supersonic moist air flow, the dependency of location of reflection of oblique shock wave generated by the wavy wall, and the distributions of flow properties in the flow field, on the stagnation relative humidity and temperature is clarified by the plots of streamline, iso-Mach number and iso-flow properties of numerical result and the schlieren photographs of experiment. And. experimental and numerical results are in good agreement.
폴리머 폼의 비선형 인장거동을 모사하기 위한 기공이 고려된 손상 탄성 구성방정식
권순범,이제명 한국전산구조공학회 2018 한국전산구조공학회논문집 Vol.31 No.4
폴리머 폼은 다공성을 가장 큰 특징으로 하는 재료이기 때문에, 본 연구에서 비가역 열역학 관점을 기반으로 폴리머 폼의 기공 성장 및 합체를 고려한 손상 탄성 구성방정식을 개발하였으며, 개발된 구성방정식은 unilateral 손상의 효과를 고려하였다. 유한요소해석의 적용을 위해 상용 유한요소해석 프로그램인 ABAQUS의 사용자 서브루틴 UMAT을 이용하여 제안된 구성방정식을 수치적으로 구현하였다. 비선형 유한요소해석 결과와 폴리머 폼의 인장 시험 결과와 비교를 통해 제안된 손상 모델의 유효성을 검증하였으며, 제안된 구성방정식의 재료모델상수가 손상에 미치는 영향에 대해 분석하였다. This paper details the development of an isotropic elastic-damage constitutive model for polymeric foam based on irreversible thermodynamics to consider the growth and coalescence of voids. The constitutive equations describe the material behavior sustaining unilateral damage. To facilitate finite element analysis, the material properties for specific types of polymeric foams are applied to the developed model; the model is then implemented in ABAQUS as a user-defined material subroutine. To validate the developed damage model, the simulated results are compared to the results of a series of tensile tests on various polymeric foams. The proposed damage model can be utilized to further research on continuum damage mechanics and finite element analysis of polymeric foams in computational engineering.
권순범,윤의수,김병지 대한기계학회 1994 대한기계학회논문집 Vol.18 No.8
The rapid expansion or condensible gas such as moist air of steam gives rise to nonequilibrium condensation. As a result of irreversibility of condensation process in the supersonic cascade flow of low pressure steam turbine, the entropy of the flow is increased, and the efficiency of the turbine is decreased. In the present study, to investigate the flow of moist air in 2-dimensional cascade made as the configuration of the tip section of the last actual steam turbine moving blade, the static pressure at both sides of pressure and suction of blade are measured by static pressure taps and the distribution of Mach number on both surfaces of the blade are obtained by using the measured static pressure. Also, the flow field is visualized by a schlieren system. From the experimental results, the effects of the stagnation temperature and specific humidity on the flow properties in a 2-dimensional stationary cascade of a practical steam turbine blade are clearly identified.
권순범,어수락,조상헌,이광수,이해원 동국대학교 의학연구소 2009 東國醫學 Vol.16 No.1
이물질 주사를 통한 음경 확대술은 비교적 흔히 행하여 지고 있는 시술로, 바셀린,실리콘과 파라핀 등이 주로 사용되고 있으며, 이로 발생하는 심각한후유증에 대한 경각심이 커짐에도 불구하고 음경의 둘레를 확대하기 위해 비의료인에 의해 행하여지고 있다. 합병증으로는 음경모양의 변형, 염증반응,피부괴사,육아종, 색전증과 악성 종양 등이 발생할 수 있다. 음경의 이물 육아종세 대한 치료는 이물질에 의하여 침윤된 피부,피하 조직의 완전한 제거와 다양한 국소 피판 또는 피부이식에 의한 음경 재피복으로 이루어 진다. 광범위한 음경 피부 결손의 경우 부분층 피부 이식이 우선 고려될 수 있으나, 음경해면체(corpora cavernosa)까지 이물질이 침윤한 경우 육아종의 완전한 제거가 불가능할 수 있으며, 수술 후 잔류 육아종은 피부이식의 생착을 어렵게 한다. 이러한 경우에는 안전한 음경 재피복을 위하여 음낭 피판을 사용할 수 있다. 음낭 피부는 이소성 모발성장을 보이는 경향에도 불구하고, 뛰어난 신축성과 풍부한 혈관 분포로 안해 마피 음경체(denuded penis)의 재피복을 위한 훌륭한 재료로 판단된다. 저자들은 음경의 이물 육아종 제거 후 발생한 광범위한 피부 결손이 었는 3명의 환자를 음낭 피판으로 치료하였다. 3명 모두에서 별다른 합병증 없이 만족스런 결과를 보였다. Penile augmentation with foreign body injection is a relatively common practice. Materials such as vaseline, silicone and paraffin are usually injected. Despite awareness of the potentially damaging effects of these practices, they are still being used by laymen in attempts to increase the circumference of the penile shaft. Penile deformity, inflammation, tissue necrosis, granuloma, embolism and malignant tumor are some of the complications that may follow. Treatment plan for patients with large penile foreign body granuloma include complete removal of foreign body infiltrated skin and subcutaneous tissue, followed by penile resurfacing with skin graft or various local flaps. Thick, nonmeshed, split-thickness skin grafts are preferred for extensive penile reconstruction. But, sometimes the foreign body infiltration of corpora cavernosa makes complete removal of foreign body granuloma impossible, and the remnant foreign body granuloma does not permit skin graft coverage. For patients with such problems, scrotal flaps can be utilized for safe coverage. The scrotal skin, with high elasticity and vascularity, has proven to be a good material for reconstruction of denuded penis, despite its hair bearing nature. We have treated 3 patients with penile foreign body granuloma using scrotal flaps. The postoperative course was uneventful. All flaps survived with no significant complications.
Numerical analysis for the coating thickness prediction in continuous hot-dip galvanizing
권순범,권영두,이성진,신승영,Geun-Young Kim 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.12
Gas wiping is a decisive operation in the hot-dip galvanizing process. Especially, it has a crucial influence on the thickness and uniformity of coating film, but may be subsequently responsible for splashing. To date, the number of fundamental studies on the jet structure impinging on a vertical moving strip for various nozzle systems has not been sufficient to draw any meaningful conclusion. In this connection, at first, to confirm the validation of numerical analysis, the impinging jet pressure on the surface of a vertical strip by experiment is compared with the results by numerical analysis. Next, after confirming for the superiority of a constant expansion rate nozzle in splashing, the relationship between the stagnation pressure and the impinging jet pressure distribution issuing from the nozzle system of constant expansion rate is investigated. Finally, by using the calculated wall shear stress, the relationships among the coating thickness, strip speed and nozzle stagnation pressures are clarified. It is found that the impinging wall pressure for the case of constant expansion rate nozzle is more favorable for the problem of splashing to the case of the conventional one. Furthermore, from the point of view of energy conservation, it is advisable to use a constant expansion rate nozzle as a gas-wiping nozzle.