• Journal of Mechanical Science and Technology
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• 제18권8호
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• pp.1435-1450
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• 2004

Experimental data are presented which describe the effects of a combustor-level high free-stream turbulence on the near-wall flow structure and heat/mass transfer on the endwall of a linear high-turning turbine rotor cascade. The end wall flow structure is visualized by employing the partial- and total-coverage oil-film technique, and heat/mass transfer rate is measured by the naphthalene sublimation method. A turbulence generator is designed to provide a highly-turbulent flow which has free-stream turbulence intensity and integral length scale of 14.7% and 80mm, respectively, at the cascade entrance. The surface flow visualizations show that the high free-stream turbulence has little effect on the attachment line, but alters the separation line noticeably. Under high free-stream turbulence, the incoming near-wall flow upstream of the adjacent separation lines collides more obliquely with the suction surface. A weaker lift-up force arising from this more oblique collision results in the narrower suction-side corner vortex area in the high turbulence case. The high free-stream turbulence enhances the heat/mass transfer in the central area of the turbine passage, but only a slight augmentation is found in the end wall regions adjacent to the leading and trailing edges. Therefore, the high free-stream turbulence makes the end wall heat load more uniform. It is also observed that the heat/mass transfers along the locus of the pressure-side leg of the leading-edge horseshoe vortex and along the suction-side corner are influenced most strongly by the high free-stream turbulence. In this study, the end wall surface is classified into seven different regions based on the local heat/mass transfer distribution, and the effects of the high free-stream turbulence on the local heat/mass transfer in each region are discussed in detail.

• 한국터널지하공간학회 논문집
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• 제17권3호
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• pp.267-281
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• 2015

본 연구에서는 흙막이벽과 같은 수직굴착과 터널과 같은 지하공간의 연속적인 굴착에 따른 지반 거동과 토압 변화를 실험적으로 연구하였다. 굴착 단계별로 벽체 거동, 토압 변화, 그리고 지표 침하의 측정이 가능한 길이 160cm, 높이 120cm의 모형 토조를 제작하였다. 실험은 균일하게 조성된 사질토 지반에서 벽체에 임의의 변위를 가하고, 토압 변화와 지표 침하를 확인하는 방식으로 수행하였다. 모형실험은 흙막이벽과 지하공간의 연속적인 시공을 모사하기 위하여 흙막이벽 굴착을 모사하는 우측벽체 10개 및 지하공간 굴착을 모사하는 하부벽체 5개를 순서대로 거동시켜 모사하였다. 실험 결과, 벽체의 주동변위로 감소된 토압이 주변 벽체로 분담되는 아칭현상이 모든 벽체에서 발생함을 확인하였다. 연속되는 시공을 모사한 실험에서 phase마다 아칭현상을 확인할 수 있으나, 하부1단 벽체의 거동 시, 우측10단 벽체는 다른 경우와 달리 토압이 50%정도만 회복됨을 보였다.

• Journal of Yeungnam Medical Science
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• 제3권1호
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• pp.237-241
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• 1986

본 교실에서 백서의 대퇴동맥을 이용하여 혈관감자의 회전없이 continuous suture로 미세혈관 문합을 시행해본 결과 다음과 같은 결론을 얻었다. end-to-end anastomosis시 double c1app의 회전이 어려울 정도로 작업공간이 제한된 경우나 end-to-side anastomosis시 secondary Vessel의 길이가 짧아서 후벽을 잘 볼 수 없는 경우에 continuous suture을 이용하면 Back wall을 완전히 노출시킨 상태에서 쉽게 혈관 문합을 시행할 수 있으며 문합시간도 단축시킬 수 있을 것으로 사료된다.

• 치과방사선
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• 제13권1호
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• pp.107-115
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• 1983

This study was performed in order to analyse the morphology of maxillary sinus on orthopantomogram. The author anlaysed the anterior-posterior width of mesial wall, the extension of anterior margin in maxillary sinus and the interrelation between the root apex of maxillary 1st molar and sinus floor. The films consisted of 514 orthopantomograms divided into three groups ranging the 3rd decade, 4th and 5th decade and 6th decade. The obtained results were as follows: 1. The mean dimensions of the anterior - posterior width of mesial wall were 43.81±4.55㎜ for male and 43.80±4.49㎜for female in the right of maxillary sinus, 43.75±74㎜ for male and 43.37±3.92㎜ for female. 2. With age, the dimensional change of the anterior - posterior width of mesial wall in maxillary sinus was not observed. 3. The extension order of anterior margin of the maxillary sinus was distal to canine side, 1st premolar mesial side, canine mesial side, and 1st premolar distal side. 4. In the distance between the root apex of upper 1st molar and the maxillary sinus floor, the degree of closeness was more increased in the older-aged group than in the younger-aged group.

• 설비공학논문집
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• 제15권10호
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• pp.809-820
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• 2003

The present study investigates effects of flow velocity on the convective heat/mass transfer characteristics in wavy ducts of a primary surface heat exchanger application. Local heat/mass transfer coefficients on the wavy duct sidewall are determined by using a naphthalene sublimation technique. The flow visualization technique is used to understand the overall flow structures inside the duct. The aspect ratio and corrugation angle of the wavy duct is fixed at 7.3 and 145$^{\circ}$ respectively, and the Reynolds numbers, based on the duct hydraulic diameter, vary from 100 to 5,000. The results show that there exist complex secondary flows and transfer processes resulting in non-uniform distributions of the heat/mass transfer coefficients on the duct side walls. At low Re (Re<1000), relatively high heat/mass transfer regions like cell shape appear on both pressure and suction side wall due to the secondary vortex flows called Taylor-Gortler vortices perpendicular to the main flow direction. However, at high Re (Re>1000), these secondary flow cells disappear and boundary layer type flow characteristics are observed on pressure side wall and high heat/mass transfer region by the flow reattachment appears on the suction side wall. The average heat/mass transfer coefficients are higher than those of the smooth circular duct due to the secondary flows inside wavy duct. And also friction factors are about two times greater than those of the smooth circular duct.

• 기술사
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• 제42권4호
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• pp.55-61
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• 2009

Retaining wall is a structure to stabilize the land slope as vertical retaining wall have constructed to make efficiency use of downtown area. Recently to commune with nature and refine a apartment and structure, natural friendly relations for retaining walls are tried to construct. The surface of the concrete walls are weave in various figures and colours, and in some places plant a shrub. Laying a landscape stone which have disclose a plane nature one means keeping up the natural slope, constructively safely set a anchor in front side and rear side wall between the natural stone, plant shrub or ground coverings to give shape into a rock. Natural stone is exposed of surface and planting the gardening, to be a type of natural friendly relations however that will be recycled. The size of blasted nature stone which is irregular become more natural type of one.

• 한국기계연구소 소보
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• 통권15호
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• pp.91-103
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• 1985

In this paper, temperature distribution and thermal stress are investigated considering engine peak pressure and the time average temperature distribution in the piston under running conditions for the diesel engine. The induced stress are calculated by the Finite Element Method(FEM). The results obtained are summerized as follows. 1) The results calculated by the FEM present good agreement with other numerical solution in literature. 2) It is confirmed that maximum compressive stress are induced in the part of outside wall between the piston crown and the pin bush. 3) In the axial direction, the hoop stresses are changed its sigh at the portion of crown near the inner wall side 4)Large gradient of temperature is shown in the piston crown near the side wall in the axial direction, in the part between the piton crown and the pin bush in radical direction 5)in case of stress distribution of piston wall surface in the axial direction, the hoop stress is a little greater than axial stress, and the latter is greater than the radial stress

• Journal of Advanced Marine Engineering and Technology
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• 제9권2호
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• pp.143-152
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• 1985

In this paper, temperature distribution and thermal stress are investigated considering engine peak pressure and the time average temperature distribution in the piston under running conditions for the marine diesel engine. The induced stress are calculated by the Finite Element Method (FEM). The results obtained are summerized as follows. 1) The results calculated by the FEM present good agreement with other numerical solution in literatures. 2) It is comfirmed that the maximum compressive stresses are induced in the part of outside wall between the piston crown and the pin bush 3) In the axial direction, the hoop stresses are changed its sign at the portion of crown near the inner wall side. 4) Large gradient of temperature is shown in the piston crown near the side wall in the axial direction, in the part between the piston crown and the pin bush in radial direction. 5) In case of stress distribution of piston wall surface in the axial direction, the hoop stress is a little greater than axial stress, and the latter is greater than the radial stress.

• 대한영상의학회지
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• 제85권4호
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• pp.813-819
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• 2024

이소성 유방 조직은 배아발생 과정 중 유선의 불완전한 퇴화로 발생하며 인구의 0.2%-6%를 차지한다. 흉벽이나 복벽에 발생한 이소성 유방암은 특히 드물게 보고되었다. 본 연구에서는 양측 전흉벽의 이소성 유방에 유방암과 섬유선종이 동시에 발생한 38세 여성의 매우 드문 사례를 초음파 및 자기공명영상 소견과 함께 보고하고자 한다.

• 한국구조물진단유지관리공학회 논문집
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• 제7권2호
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• pp.201-208
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• 2003

In domestic, bearing wall apartment building have not rectangular walls but irregular walls which are designed at walls of various cross-sectional shapes such as H-shaped, T-shaped, Box-shaped and L-shaped. In these irregular walls connected with rigid joint each other, one side walls of irregular walls is expected to show effective behavior for rigid-jointed the other side walls. Moreover, previous studies have focused on simplifying irregular walls into rectangular walls because of the complication in structural design and analysis. So studies for variables affecting behaviors of irregular walls, such as aspect ratios and compressive strength of concrete, are insufficient. The objective of this study is to evaluate the behaviors of T-shaped structural walls with different concrete compressive strengths and aspect ratios by experimental works. Results of this experimental study show that flange wall is contributed to increase the flexural strengths by the variation of concrete strengths and aspect ratios, and that it is needed to evaluate the effect width of flange wall for rational wall design.