• 대한기계학회논문집B
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• 제23권8호
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• pp.1063-1071
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• 1999

Fine grid calculations are reported for the developing turbulent flow in a curved duct of square cross-section with a radius of curvature to hydraulic diameter ratio ${\delta}=Rc/D_H=3.357 $ and a bend angle of 720 deg. A sequence of modeling refinements is introduced; the replacement of wall function by a fine mesh across the sublayer and a low Reynolds number algebraic second moment closure up to the near wall sublayer in which the non-linear return to isotropy model and the cubic-quasi-isotropy model for the pressure strain are adopted; and the introduction of a multiple source model for the exact dissipation rate equation. Each refinement is shown to lead to an appreciable improvement in the agreement between measurement and computation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.453-460
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• 2000

A test rig is developed for performance test of 1 stage axial-type turbine which is designed by meanline analysis, streamline curvature method, and blade design method using configuration parameters. The purpose of this study is to find the best configuration parameters for designing a high efficiency axial-type turbine blade. To measure the efficiency of turbine stage, a dynamo-meter is installed. Two different stators which are manufactured as an integrated type are developed, and a rotor blade and 5 sets disc are developed for setting different stagger angle. The tip and hub diameters of the test turbine are 300 and 206.4mm, respectively. The rotating speed is 1800RPM, and the extracted power is 2.5kW. Flow coefficient is 1.68 and the reaction factor at meanline is 0.373. The number of stator and rotor of test turbine are 31 and 41, respectively. The Mach number of stator exit flow near hub is 0.164.

• 한국정보통신학회논문지
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• 제10권5호
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• pp.905-909
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• 2006

최근 시야각 개선을 위한 다양한 커브형 집적 영상 시스템이 연구되어 왔지만, 광학적 구현에 있어서 한축으로만 제한되었다. 본 논문에서는 기존의 집적 영상 시스템에서 큰 구경의 렌즈를 추가적으로 사용하여 구현되는 전방향 커브형 집적 영상 시스템을 제안하고, 제안하는 시스템에서의 요소영상을 제작하는 방법을 설명한다. 제안한 시스템은 모든 방향에 대해서 커브 효과를 제공할 수 있고, 단순한 시스템의 구조를 가지는 것을 특징으로 한다. 전방향 커브형 집적 영상 시스템에 대해서 John 행렬을 도입한 기하광학적 분석을 수행하고, 이를 이용하여 새로운 요소 영상을 제작하였다. 제작한 요소영상의 성능을 확인하기 위해서 기초적인 광학적 실험을 수행하고, 그 실험 결과를 보고한다.

• 한국정보전자통신기술학회논문지
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• 제4권4호
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• pp.242-249
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• 2011

본 연구에서는 척추측만증의 정도를 자동으로 검출할 수 있는 알고리즘을 개발하였다. 개발한 시스템은 X-ray 영상 원본을 사용하였다. 척추 만곡 정도에 대한 수식은 S<0 이고, L>0 인 성립 조건을 갖는 $Y=SX^2+L$의 함수식이다. X축의 길이는 변경이 가능하고 모든 척추선 함수 그래프에서 동일하게 적용되었으며, 기울기 $S=-L/92^2$이다. 척추측만증 정도에 대한 미분 그래프의 수식은 Y'=2SX임을 알 수 있었고, 추출된 척추선에 대한 분류와 척추측만증 정도에 대한 분류가 가능한 알고리즘으로 판단된다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.525-530
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• 2007

Although just developed in recent years, curved box girder has widely used in modern highway system due to their load resistance capacity as well as aesthetic considerations. According to recent literature reviews on curved box girder designs, distortional load was not considered as much as it deserves to be. In practice, the effect of distributional force is very small in straight bridge systems but yet unknown how it is in curved bridge systems. For the reason, this paper will show up an extensive parametric study on distortional behavior of curved box girder with trapezoidal section. Based on Dabrowski formulas, using finite element method, various bridges were investigated. In this study, following parameters will be included: span length, curvature radius, section height, section width, and internal section angle (web slope). From the obtained results, some initial geometric parameters are proposed for curved box girder bridges.

• 산업기술연구
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• 제29권A호
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• pp.111-122
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• 2009

In this study, flood stage was computed by HEC-RAS, 1-D numerical analysis model and FESWMS-2DH, 2-D numerical model. Flood stages computed by two different models were compared for straight line, dot axle watercourse, dead-zone watercourse, section sudden-changing watercourse, and curved watercourse. From the results, flow velocity and water level were similar in straight watercourse and dot-reduction watercourse. However, there was difference of flow velocity and water level in dead-zone watercourse, sudden expansion, dot-reduction, and curve-watercourse. This result might be influenced by rapid change of watercourse due to dead-zone, the angle of inflow and outflow, and the curvature. Especially in this study, numerical model was applied to Wol-Song-Cheon at Chuncheon in order to analyze the effect of flood stage by two different models. By flowing properties around the bridge and confluence of rivers, it was found that flow velocity and water level was changed. Therefore, it was concluded that a lot of uncertainties are contained in the present bank.

• Physical Therapy Rehabilitation Science
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• 제12권1호
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• pp.19-25
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• 2023

Objective: Patients with scoliosis complain of various symptoms such as muscle imbalance, dysfunction, back pain, abnormal posture and gait abnormality. The most basic treatment for scoliosis is to observe the progress based on conservative treatment. Therefore, in this case report, the effect of cytoskeletal manual therapy (CMT), a soft tissue mobilization technique, on pain intensity, muscle thickness, and pressure pain threshold (PPT) in a patient with scoliosis was investigated. Design: A case report Methods: A 25-year-old male diagnosed with scoliosis visited the Neuromusculoskeletal Science Laboratory with chronic back pain. In the laboratory, scoliosis was confirmed through the X-ray image used for his diagnosis, and it was confirmed again through Adam's forward bending test. Pain, pressure pain threshold and muscle thickness were measured to compare the immediate effects of CMT applied in the laboratory for 40 minutes. Treatments were visited two weeks after the first visit and outcome measures were assessed after a total of two visits. Results: After receiving CMT up to the second session, the pain intensity decreased by 4 points and the screening angle decreased by 15 degrees. Muscle thickness decreased in all but 10 mm on the dominant side of the thoracic spine. All of the PPTs increased, and the greatest increase was 3.1 lb on the dominant side of the thoracic spine. Conclusions: CMT showed positive improvement in pain during trunk flexion, spinal curvature, muscle imbalance, and pressure pain, which is considered as an ancillary treatment option for scoliosis management.

• 한국기계가공학회지
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• 제14권6호
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• pp.41-48
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• 2015

Stainless steel mesh has been used as a filter in various fields, including domestic, medical, etc. However, the surface before machining may have an adverse effect the product quality and performance because it is not smooth. Especially, adsorbed impurities in the surface result in difficulty in cleaning. Therefore, in this paper, we propose an improved surface quality through electrochemical polishing (ECP). Two electrodes, composed of STS304 (anode) and copper (cathode) underwent machining with two conditions according to polishing time and current density. As the polishing time and current density increase, the surface of curvature decreases, and roughness and material removal rate (MRR) improves. The machined surface roughness and image were obtained through the atomic force microscope (AFM) and stereoscopic microscope. The study also analyzed hydrophilic effect through contact angles. This obtains corrosion resistance, smoothness, hydrophilic property, etc.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.321-325
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• 2005

Bipolar plate is the main part with MEA in automotive PEMFC. It must have a good electrical conductivity and excellent corrosion resistance, be cost effective. Therefore, stainless steels have been studied by many researchers because of its corrosion resistance and cost benefits. But their properties are not sufficient for the application to bipolar plate for automotive PEMFC. In this work, we have performed stamping using various commercial stainless steels to select candidate material for biploar plate and to derive design parameters for stamping simulation. The results showed that a small curvature at the corner of flow field is more favorable due to easier a plastic deformation. Stamping process was simulated by changing surface condition, and the size and angle of channel. The optimum shape and spring back phenomena were evaluated. Surface coating was applied to increase the corrosion resistance and electrical conductivity of stainless steel. The electrical interfacial resistance was 10 to $15m{\Omega}cm^2$ under clamping force of 150psi. But corrosion resistance of coating on the stainless steel was not good due to the unstableness of microstructure.

• 한국광학회지
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• 제26권6호
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• pp.299-305
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• 2015

사람 눈의 각막에 평행하게 입사하는 광선의 높이에 따른 결상점을 근사 없이 스넬의 법칙으로 분석하였다. 광선들이 망막의 동일한 한 점에 결상하도록 각막에 입사하는 광선들의 높이에 따른 입사각을 계산하기 위하여 결상점으로부터 광선을 역추적하여 각막 전면에 입사하는 광선의 입사각을 계산 하였다. 눈 자체로는 구면수차를 유발할 수밖에 없기 때문에, 구면 수차를 보정할 수 있는 비구면 렌즈 설계에 대한 조건을 유도 하였다. 계산을 쉽게 하기 위하여 렌즈 후면은 구면으로 고정하고 렌즈 전면을 비구면 렌즈 설계를 위하여 높이에 따른 곡률을 계산하였다.