• 한국유체기계학회 논문집
• /
• 제16권3호
• /
• pp.39-47
• /
• 2013

Effect of semicircular rib or groove on the performance of a rim-seal was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations. The turbulence was modeled using the one-equation Spalart-Allmaras turbulence closure model. Reynolds number based on the axial chord of the turbine blade was 500,000 at the mainstream outlet. The numerical results for a sealing effectiveness was validated in comparison with experimental data. To examine the effect of the semicircular rib or groove on sealing effectiveness of the rim-seal, location and diameter of the rib or groove were selected as the parameters to be performed. The rim-seals with the semicircular groove showed a higher sealing effectiveness than that with the semicircular rib. The semicircular groove installed on the stator side showed best sealing effectiveness among the numerical simulation results.

• Advances in concrete construction
• /
• 제7권3호
• /
• pp.191-201
• /
• 2019

Bamboo concrete bond behaviour is investigated through pullout test in this work. The bamboo strip to be used as reinforcement inside concrete is first treated with chemical adhesive to make the bamboo surface impermeable. Various surface coatings are explored to understand their water repellant properties. The chemical action at the bamboo concrete interface is studied through different chemical coatings, sand blasting, and steel wire wrapping treatment. Whereas mechanical action at the bamboo concrete interface is studied by developing mechanical interlock. The result of pullout tests revealed a unique combination of surface treatment and grooved bamboo profile. This combination of surface treatment and a grooved bamboo profile together enhances the strength of bond. Performance of a newly developed grooved bamboo strip is verified against equivalent plain rectangular bamboo strip. The test results show that the proposed grooved bamboo reinforcement, when treated, shows highest bond strength compared to treated plain, untreated plain and untreated grooved bamboo reinforcement. Also, it is observed that bond strength is majorly influenced by the type of surface treatment, size and spacing of groove. The changes in bamboo-concrete bond behavior are observed during the experimentation.

• 한국어류학회지
• /
• 제24권3호
• /
• pp.230-233
• /
• 2012

과거 우리나라 남해에 출현하는 것으로 알려졌던 농어목 새다래과의 한국미기록종 흰꼬리타락치(Taractichthys steindachneri)에 대해 제주도를 포함한 남해에서 채집된 2개체(표준체장 224.7~406.5 mm)의 표본을 근거로 형태적 특징을 상세히 기재하였다. 본 종은 양측 배지느러미가 서로 멀리 떨어져 위치하는 점, 미병부 배측에 반월상의 홈이 있는 점, 등지느러미와 뒷지느러미가 길게 신장하는 점, 그리고 체색이 전체적으로 검고 꼬리지느러미 후연이 백색인 점이 특징이다.

• Journal of Chest Surgery
• /
• 제26권12호
• /
• pp.909-914
• /
• 1993

Complete and optimal visualization of the mitral apparatus is a prerequisite for accurate repair or replacement of the mitral valve. A vertical left atriotomy just posterior to the interatrial groove is the most commonly used approach. However,exposure can be difficult under certain circumstances,such as small left atrium or reoperation. Other approaches have been advocated to deal with this difficult situations. We used an extended transseptal approach in 10 patients and good clinical results and excellent educational effects were obtained. The extended transseptal approach combines two semicircular atrial incisions circumscribing the tricuspid and mitral annuli anteriorly and superiorly,allowing exposure of the mitral valve by deflecting the ventricular side using stay sutures. The right atrium is opened anteriorly along the atrioventricular sulcus. The atrial septum is incised vertically through the fossa ovalis. Right atrial and septal incisions are joined at the superior end of the interatrial septum and extended across the dome of the left atrium to the left atrial appendage. The mitral valve was replaced in all 10 patients. Four of 10 patients had other simultaneous valve procedure: one had aortic valve replacement: 2 underwent tricuspid annuloplasty: 1 had aortic valve replacement and tricuspid annuloplasty. There was no hospital death and complication. Among the 5 patients who had atrial fibrillation preoperatively,4 had atrial fibrillation postoperatively,1 converted to sinus rhythm. The five patients who were in normal sinus rhythm preoperatively remained in sinus rhythm after replacement. A review of our results with this approach confirms the efficacy and safty of this method. So we recommanded this approach for routine mitral valve procedure,especially difficult situations,such as a small left atrium or the redo operation.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제31권6호
• /
• pp.469-477
• /
• 2009

육안적 검사결과 실험군과 대조군 모두에서 특별한 염증 소견이나 창상 이개 없이 반원 모양의 골형성이 관찰되었다. 조직학적으로 3주째에 대조군, 실험 1군, 실험2군, 실험 3군 모두 이식골 주위 및 티타늄 반구 내면을 따라 신생 골형성이 관찰되었다. 조직학적으로 6주째에 모든 군에서 3주째에 비하여 신생골 면적의 증가 및 성숙 소견이 관찰되었고, 실험2군에서는 부분적으로 이식골이 흡수되면서 신생골이 형성되는 것이 관찰된 반면, 실험 3군에서는 이식골의 흡수 소견이 관찰되지 않았다. 조직형태계측학적으로 3주, 6주 모두 자가골에서 가장 많은 신생골 형성이 나타났고, 신생골 면적 비교시 자가골, 이종골, 합성골 순으로 크게 나타났고, 각 군간의 통계학적으로 유의한 차이는 없었다(p>0.05). 본 연구결과 골유도 재생술시 골형성 능력은 자가골이 가장 좋지만, 자가골 채취가 불가능할 경우, 적절한 차폐막을 사용한 합성골과 이종골 복합 이식방식도 좋은 대체제가 될 것으로 생각된다.