• Advances in pediatric surgery
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• 제4권1호
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• pp.67-73
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• 1998

신생아 및 영아에서의 횡격막 이완증은 일반적으로 드문 질환으로 인식되어 있지만 이에 대한 정확한 진단과 적절한 원인별 처치의 필요성은 널리 알려진 사실이다. 최근 저자 등은 5 례의 선천성 횡격막 이완증을 경험할 수 있었고, 전 례 모두 수술이 적응되었다. 전 례 모두 생후 2개월 미만의 영아였고 모두 남아였다. 이완 부위는 전 예에서 좌측 횡격막이었다. 증상은 3례에서 호흡기 증상이 있었고 소화기계 증상은 없었으며 나머지 1례에서는 체중 증가불능 이 외는 무증상이었다. 전 예에서 방사선학적 변화가 저명하였고, 횡격막의 절정은 제 3에서 제 5늑간에 달하였다. 수술 술기로 저자 등은 경복부 접근 방법에 의한 횡격막 습벽 봉합술을 선호하였으며 수술 결과는 임상적으로나 방사선학적으로 우수하였다.

• 대한기계학회논문집
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• 제12권3호
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• pp.397-408
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• 1988

본 연구에서는 세가지 형상비의 연강판타원벌지 시험에 대하여 다이반경부분 의 형상과 수직이방성을 고려하여 해석고 이에 따른 실험과 비교검토하여 타원벌지시 험에서의 변형특성에 대해 논의하고자 한다. 또 불안정현상이 일어나는 압력을 예측 하여 실험에서 구한 파괴압력과 비교하여 타원벌지 시험에서의 파괴특성을 고찰하고자 한다.

• 한국전산유체공학회지
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• 제20권1호
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• pp.77-83
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• 2015

Flow characteristics of synthetic jet based flow supplying devices have been computationally investigated for different device shapes. Jet momentum was produced by the volume change of a cavity by two piezoelectric-driven diaphragms. The devices have additional flow path compared with the original synthetic jet actuator, and these flow path changes the flow characteristics of synthetic jet actuator. Four non-dimensional parameters, which were functions of the shapes of the additional flow path, were considered as the most critical parameters in jet performance. Comparative studies were conducted to compare volume flow rate and jet velocity. Computed results were solved by 2-D incompressible Navier-Stokes solver with k-w SST turbulence model. Detailed computations revealed that the additional flow path diminishes suction strength of the synthetic jet actuator. In addition, the cross section area of the flow path has more influence over the jet performances than the length of the flow path. Based on the computational results, the synthetic jet based flow supplying devices could be improved by applying suitable shape of the flow path.

• 한국철도학회논문집
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• 제1권1호
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• pp.30-39
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• 1998

The functions of diaphragms at abutments and piers of PSC box girder railway bridge are to transfer forces from the superstructure onto bearings or columns and to stiffen the superstructure cross-section against in -plane deformation. Due to stress disturbance at diaphragm, the design for the diaphragm using conventional design method is relatively irrational than those for other structural members. And, due to contribution to boundary condition of deck slab by the diaphragm, the behavior of deck slab near the diaphragm is different from that of the deck slab obtained from two dimensional analysis of the bridge, which is basis for the design of deck slab. In this paper, three dimensional behavior of deck slab near the diaphragm of prestressed concrete (PSC) box girder railway bridge constructed by the precast span method are analyzed by using three dimensional finite element modeling and using the strut-and-tie model design of the diaphragm are presented. The modeling techniques used in this paper can be applied effectively to examine the causes of cracks at deck slab near diaphragm and to design diaphragm rationally.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.961-966
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• 2003

In recent, the design of diaphragm which is representative disturbed region in PSC box girder bridge have been performed according to the empirical method or beam theory. But, these methods couldn't be described the behavior of the end diaphragm, and placed reinforcements accurately. As the compressive stress transferred by the web concentrated on the lower parts of diaphragm, it was demonstrated that the basic assumption of 2-D strut-and-tie model for the diaphragm that the compressive stress acts on the upper parts of the diaphragm is wrong. Meanwhile, in this research, after analyzing the variables of end diaphragm, the 2-D strut-and-tie models appropriate to each cases are proposed. And, the problems of 2-D strut-and-tie model were analyzed, so 3-D strut-and-tie model is proposed as well. There is no codes which include the demonstration of safety of 3-D strut-and-tie model. Hence, for nodes, the stresses at the elements which included the singular node in strut-and-tie model were investigated using the finite element analysis. And, the stress states of strut has one direction, so effective stresses were considered at the stage, dimensioning of the model. From the results, 3-D strut-and-tie model could predict the behavior of end diaphragm accurately, and design of reinforcement could be performed economically.

• Structural Engineering and Mechanics
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• 제64권2호
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• pp.195-204
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• 2017

Analytical and experimental studies of the innovative pipe in pipe damper have been recently investigated by the authors. In this paper, by adding lead or zinc infill or slit diaphragm inside the inner pipe, it is tried to increase the equivalent viscous damping ratio improving the cyclic performance of the recently proposed multi-level control system. The damper consists of three main parts including the outer pipe, inner pipe and added complementary damping part. At first plastic deformations of the external pipe, then the internal pipe and particularly the added core and friction between them make the excellent multi-level damper act as an improved energy dissipation system. Several kinds of added lead or zinc infill and also different shapes of slit diaphragms are modeled inside the inner pipe and their effectiveness on hysteresis curves are investigated with nonlinear static analyses using finite element method by ABAQUS software. Results show that adding lead infill has no major effect on the damper stiffness while zinc infill and slit diaphragm increase damper stiffness sharply up to more than 10 times depending on the plate thickness and pipe diameter. Besides, metal infill increases the viscous damping ratio of dual damper ranging 6-9%. In addition, obtained hysteresis curves show that the multi-level control system as expected can reliably dissipate energy in different imposed energy levels.

• Structural Engineering and Mechanics
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• 제61권4호
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• pp.475-481
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• 2017

An overhead travelling crane structure of two doubly symmetric welded box beams is designed for minimum cost. The rails are placed over the inner webs of box beams. The following design constraints are considered: local buckling of web and flange plates, fatigue of the butt K weld under rail and fatigue of fillet welds joining the transverse diaphragms to the box beams, fatigue of CFRP (carbon fibre reinforced plastic) laminate, deflection constraint. For the formulation of constraints the relatively new standard for cranes EN 13001-3-1 (2010) is used. To fulfill the deflection constraint CFRP strengthening should be used. The application of CFRP materials in strengthening of steel and concrete structures are widely used in civil engineering applications due to their unique advantages. In our study, we wanted to show how the mechanical properties of traditional materials can be improved by the application of composite materials and how advanced materials and new production technologies can be applied. In the optimization the following cost parts are considered: material, assembly and welding of the steel structure, material and fabrication cost of CFRP strengthening. The optimization is performed by systematic search using a MathCAD program.

• 한국항공우주학회지
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• 제34권6호
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• pp.35-41
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• 2006

본 논문에서는 무밸브 마이크로펌프에 사용되는 압전 다이아프램의 성능을 향상시키는 방법이 연구되었다. 큰 작동 변위와 작동력을 가지는 원형 형태의 경량 압전 복합재료 작동기(LIPCA)를 마이크로 펌프용으로 제작하였다. 유한요소 해석과 실험을 통하여 원형 LIPCA의 성능을 예측하여 최적의 적층 형태를 설계하였다. 최적의 원형 LIPCA를 기반으로 포토리소그라피법과 PDMS 몰딩법을 사용하여 무밸브 마이크로 펌프를 제작하였다. 압전 다이아프램의 작동 변위 및 마이크로 펌프의 유량과 배압을 실험적으로 계측하였고, 반경험식을 사용하여 예측한 유량과 비교하였다. 이상의 연구에서 원형 LIPCA가 마이크로 펌프용으로 사용되는 보통의 압전 작동 다이아프램을 대체할 수 있는 우수한 작동기임을 확인할 수 있었다.

• 반도체디스플레이기술학회지
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• 제2권4호
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• pp.19-22
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• 2003

In this paper, Si anisotropic etching characteristics of tetramethylammonium hydroxide (TMAH)/ammonium persulfate (AP) solutions were investigated to realize the optimum structure of a diaphragm for the piezoresistive pressure sensor application. Due to its low toxicity and its high compatibility with the CMOS processing, TMAH was used as Si anisotropic etchants. The variations of Si etch rate on the etching temperature, TMAH concentration, and etching time were obtained. With increasing the etching temperature and decreasing TMAH concentrations, the Si etch rate is increased while a significant non-uniformity exists on the etched surface because of formation of hillocks on the <100> surface. With the addition of AP to TMAH solution, the Si etch rate is increased and an improvement in flatness on the etching front is observed. The Si etch rate is also maximized with increasing the number of addition of AP to TMAH solution per one hour. The Si square diaphragms of 20$\mu\textrm{m}$ thickness and 100-400 $\mu\textrm{m}$ one-side length were fabricated successfully by adding AP of (5/6)g to 800 ml TMAH solution every 10 minutes.

• 한국철도학회논문집
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• 제8권1호
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• pp.41-50
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• 2005

Steel -Concrete Composite two girder railway bridges applying high performance steel with extra thick plate have economic and aesthetic advantages due to the simplification of manufacturing and construction process. However, steel bridges are seldom adopted in domestic railway bridge, since steel bridges are not efficient as R.C bridges considering dynamic characteristics and noise, etc. While highway bridges do not have lower horizontal bracing and larger interval of diaphragm cross beam, railway bridges install lower horizontal bracings to control the torsion due to heavy eccentrical line load. Accurate finite element analysis were performed with the parameters of existence of bracing and bracing shape, with the cross beam interval and stiffness, etc. To find out the effects of secondary members such as horizontal bracings and diaphragms, static md dynamic analysis have been performed by using finite element method. In this study, few member plate-girder bridges are analyzed with variable span lengths to examine the dynamic behavior and limits of damping. And though lateral bracings are members against torsion, but lateral bracing's absence is no big problem. Time history analysis using mode superposition method makes proof of this result.