• Title/Summary/Keyword: numerical methods

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Free Vibrations of Timoshenko Beam with Elastomeric Bearings at Two Far Ends (양단이 탄성받침으로 지지된 Timoshenko 보의 자유진동)

  • Lee, Byoung Koo;Lee, Tae Eun;Park, Chang Eun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.3A
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    • pp.181-187
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    • 2011
  • This paper deals with free vibrations of the Timoshenko beam supported by two elastomeric bearings at two far ends. The ordinary differential equation governing free vibrations of such beam is derived, in which both effects of rotatory inertia and shear deformation are included as the Timoshenko beam theory. Also, boundary conditions of the free end are derived based on the Timoshenko beam theory. The ordinary differential equation is solved by the numerical methods for calculating natural frequencies and mode shapes. Both effects of the rotatory inertia and shear deformation on natural frequencies are extensively discussed. Also, relationships between natural frequencies and slenderness ratio, foundation modulus and bearing length are presented. Typical mode shapes of bending moment and shear force as well as deflection are given in figures which show the positions of maximum amplitudes and nodal points.

Performance Enhancement Study Using Passive Control of Shock-Boundary Layer Interaction in a Transonic/Supersonic Compressor Cascade (천음속/초음속 압축기 익렬에서 Shock-Boundary Layer 상호작용의 수동적 제어에 의한 성능 향상 연구)

  • Kim, Sang-Deok;Gwon, Chang-O;Sa, Jong-Yeop
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.9
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    • pp.2944-2952
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    • 1996
  • In this paper the CSCM type upwind flux difference splitting Navier-Stokes method has been applied to study the ARL-SL19 transoni $c^ersonic compressor cascade flow. First, the general characteristics of baseline cascade flow were analyzed. At freestream Mach n.1.612 and exit/inlet pressure ratio 2.15, the results from current laminar flow were compared well in suction surface with the experiment; however, not well in pressure surface. Second, numerical study of the transoni $c^ersonic compressor cascade flow demonstrated the effectiveness of a passive control by the various size cavities. A cavity under the shock foot point at the suction surface of the blades was used as a passive control. The passive control of shock-boundary layer interaction by a cavity reduced total pressure losses. The effect of cavity length and depth was studied. The total pressure loss was reduced by about 10% and the isentropic efficiency was improved slightly. The effect of cavity depth in current study(d/l = 0.05, 0.02) was not found strong. Further adequate turbulence modeling and TVD schemes would help to capture the shock more accurately and increase the effectiveness of the current shock-boundary layer interaction study using upwind flux difference splitting computational methods.thods.

The study on substructure design and analysis for 5MW offshore wind turbine (5MW급 해상풍력 하부구조물 설계 및 해석에 관한 연구)

  • Sun, Min-Young;Lee, Sung-Bum;Lee, Ki-Yeol;Moon, Byung-Young
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.9
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    • pp.1075-1080
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    • 2014
  • This study aims at dedicating to relevant technology fields by suggesting design methods of structures and estimating their safety in relation to substructure for offshore wind power requiring high safety to various environment conditions. Especially, with respect to 5MW Offshore Wind Power System, this study will provide information about major wind directions and duration in combination with the developing wave climate at the test field. Therefore, connections between wind fields and approaching wave trains will be estimated and their intensity, direction and time shift will be pointed out. Furthermore, the local pressure distribution of breaking waves will be investigated by physical and numerical modeling. The currently applied structural and fatigue assessment of support structures for offshore wind energy converters is based on common design rules. Normally, constructions in structural engineering are treated as limited, single structures. This means that varying aspects of manufacturing are considered by high safety factors.

A Study on the Heat Transfer Performance of an Energy-Nose Section in a Household Refrigerator-Freezer (가정용 냉장고의 에너지 노즈부 열전달 특성에 관한 연구)

  • Lee, Moo-Yeon;Lee, Dong-Yeon;Kim, Yong-Chan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.6 s.261
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    • pp.574-580
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    • 2007
  • The objective of this article is to present an analysis of all heat transfer paths through the energy nose under closed door conditions when refrigeration system of household refrigerator-freezer is operating on. Both experimental and numerical methods are suggested as a means of determining the overall energy nose load amount as well as the load due to each pathway such as mullion section and F and R sides of the household refrigerator-freezer. In other words, all loads determined in this article are just energy nose and not the loads seen by the refrigeration system. We suggest good ideas for improving the heat transfer losses such as conduction and convection through the energy nose. As we can be known from the experimental test results, it is effective to prevent the heat loss of a mullion section. And energy efficiency is also decreased approximately 6% compared to that of a baseline sample test result. As we can be known from the Ansys 8.1 analysis, it is shown the steady state temperature distribution in figures from 6 to 8. And the direction of the heat flow through the energy nose section is also easily seen from that In conclusion, the article is focused on an energy nose section in household refrigerator-freezer for practical proposes which is the energy saving in a household refrigerator-freezer. And the method suggested may be applied to any make or model to aid in the search for high efficient energy nose section of household side by side refrigerator-freezer as well as top mounted refrigerator-freezer, commercial refrigerator and so on.

Real Time Textile Animation Using Fuzzy Inference (퍼지추론을 적용한 직물 애니메이션)

  • Hwang, Seon-Min;Song, Bok-Hee;Yun, Han-Kyung
    • The Journal of the Korea Contents Association
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    • v.11 no.9
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    • pp.1-8
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    • 2011
  • A fuzzy inference technique for real-time textile animation without integration at textile model based Mass-Spring model is introduced. Until now many techniques have used the Mass-Spring model to describe elastically deformable objects like textile. A textile object is able to represent as a deformable surface composed of spring and masses, the movement of textile surface which is analysed through the numerical integration by the fundamental law of dynamics such as Hooke's law. However, the integration methods have 'instability problems' if the explicit Euler's method is applied or 'large amounts of calculation' if the implicit Euler's method is applied. A simple and fast animation technique for Mass-Spring model of a textile with fuzzy inference is proposed. The stabilized simulation result is obtained the state of each mass-point in real-time for the n of mass-points by a relatively simple calculation.

Two Dimensional Visualization Simulation of Physical Law using Virtual Anomaly (가상 이상 개념을 이용한 물리법칙의 2D 시각화 시뮬레이션)

  • Park, Jung-Yong
    • The Journal of the Korea Contents Association
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    • v.10 no.11
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    • pp.1-9
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    • 2010
  • In comparison with the acquirement of knowledge by expression of symbol or numerical formula, the experience based knowledge acquirement give stable and clear understanding of information to a learner. Various educational systems based on computer such as virtual reality, intelligent learning system, visualization of concept, simulation-based system, and microworld have so far been developed. In this paper, a method of two dimensional visualization of a physical law by simulation has been suggested to educate a learner. Especially, learning the law of gravity by simulation based educational method gives a learner indirect experience that enhance the efficiency of knowledge acquirement clearly. The visualization methods of a real-time physical law and a virtual anomalies' physical law by simulation are proposed in this paper to deliver information or knowledge clearly. Then we show that a learner can acquire some knowledge effectively by the proposed method.

Meta-analysis of factors predicting resistance to intravenous immunoglobulin treatment in patients with Kawasaki disease

  • Baek, Jin-Young;Song, Min Seob
    • Clinical and Experimental Pediatrics
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    • v.59 no.2
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    • pp.80-90
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    • 2016
  • Purpose: Studies have been conducted to identify predictive factors of resistance to intravenous immunoglobulin (IVIG) for Kawasaki disease (KD). However, the results are conflicting. This study aimed to identify laboratory factors predictive of resistance to high-dose IVIG for KD by performing meta-analysis of available studies using statistical techniques. Methods: All relevant scientific publications from 2006 to 2014 were identified through PubMed searches. For studies in English on KD and IVIG resistance, predictive factors were included. A meta-analysis was performed that calculated the effect size of various laboratory parameters as predictive factors for IVIG-resistant KD. Results: Twelve studies comprising 2,745 patients were included. Meta-analysis demonstrated significant effect sizes for several laboratory parameters: polymorphonuclear leukocytes (PMNs) 0.698 (95% confidence interval [CI], 0.469-0.926), C-reactive protein (CRP) 0.375 (95% CI, 0.086-0.663), pro-brain natriuretic peptide (pro-BNP) 0.561 (95% CI, 0.261-0.861), total bilirubin 0.859 (95% CI, 0.582-1.136), alanine aminotransferase (AST) 0.503 (95% CI, 0.313-0.693), aspartate aminotransferase (ALT) 0.436 (95% CI, 0.275-0.597), albumin 0.427 (95% CI, -0.657 to -0.198), and sodium 0.604 (95% CI, -0.839 to -0.370). Particularly, total bilirubin, PMN, sodium, pro-BNP, and AST, in descending numerical order, demonstrated more than a medium effect size. Conclusion: Based on the results of this study, laboratory predictive factors for IVIG-resistant KD included higher total bilirubin, PMN, pro-BNP, AST, ALT, and CRP, and lower sodium and albumin. The presence of several of these predictive factors should alert clinicians to the increased likelihood that the patient may not respond adequately to initial IVIG therapy.

Dynamic Analysis of a Tension Leg Platform Using Morison's Equation (Morison 방정식을 이용한 Tension Leg Platform의 동정해석)

  • Pyun, Chong Kun;Park, Woo Sun;Yun, Chung Bang
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.7 no.3
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    • pp.223-228
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    • 1987
  • An efficient method for the calculation of wave forces on a tension leg platform(TLP) is presented in this paper. It is based on the Morison's equation with two corrective terms. One is the reduction of the inertia forces on the vertical columns in order to include the wave diffraction effect particularly for small wave conditions. The other is the inclusion of the hydrodynamic forces acting at the bottoms of the columns. Numerical studies are carried out for a TLP in 1000 ft water with two different wave heading angles($0^{\circ}$ and $45^{\circ}$). The reponse amplitude operators(RAO's) for the TLP motions and top tether tension variations are obtained by the present method and the theoretically more accurate method based on the diffraction theory. A comparison has been made between the results obtained by two methods.

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One case on Lumbar Kyphosis with Complaining Lower Back Pain and Low Extremity Pain (요각통으로 입원한 요추부 후만곡 환자 1례에 대한 증례보고)

  • Kwon, Hyeok-Joon;Kim, Joo-Won;Ryu, Ki-Jun;Kim, Ho-Jun;Lee, Myeong-Jong
    • The Journal of Churna Manual Medicine for Spine and Nerves
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    • v.4 no.2
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    • pp.109-120
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    • 2009
  • Objectives : We already know the importance of stability and flexibility on the vertebra. It is important to keep the lumbar lordosis for stability and flexibility. We hope to reduce lower back pain and low extremity pain by changing the angle of the Lumbar Kyphosis through conservative treatment. We have evaluated the effect of conservative treatment with Saamchimbeop Pejeonggyeok by experimenting one patient suffering from Lumbar Kyphosis with lower back pain and low extremity pain. Methods : One patients were diagnosed as Lumbar Kyphosis through X-ray examination. We used conservative treatment, especially Pejeonggyeok Treatment to the patients and measured NRS((Numerical Rating Scale), rating scale for low back pain, low extremity pain and SLR(Straight Leg Raising) test and walking time in whole term of admission, and we also measured flexion, extension angle and lumbar kyphosis using lumbar x-ray lateral view after diganosing by Lumbar Kyphosis. Results and Conclusions : After treating conservative therapy, We figured out that the patient were on the mend, and we found out the angle change in flexion, extension and lumbar Kyphosis. These results suggest that Pejeonggyeok Treatment were effective to improved Lumbar Kyphosis and reduced the low back pain.

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Two Clinical Cases on Patients with Pain And Limited Range of Motion about Shoulder Subsequent to Scapular Fracture By Oriental Medical Treatments And Chuna Treatment (견갑골 골절 후 견관절 통증 및 관절가동범위 제한을 동반한 환자에 추나와 한방 치료를 시행한 치험 2례)

  • Lee, Kyung-Moo;Lim, Sang-Hoon;Yoon, Dae-Yeon;Kim, Soon-Joong;Jeong, Su-Hyeon
    • The Journal of Churna Manual Medicine for Spine and Nerves
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    • v.4 no.2
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    • pp.99-107
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    • 2009
  • Objectives : This study was performed to evaluate the effects of oriental medical treatments and Chuna treatment on patients with pain and limited range of motion(LOM) about shoulder subsequent to scapular fracture. Methods : Two patients suffered from pain and LOM about shoulder after scapular fracture, one is scapular body fracture with multiple rib fractures, the other is only intraglenoid fracture were treated with Chuna therapy, acupuncture, herbal medicine, physical therapy and measured by VNRS(Verbal numerical rating scale) and ROM (Range of motion). Results : After oriental medical treatments and Chuna treatment, we found out a recovery from two patients suffered from pain and LOM about shoulder subsequent to scapular fracture. Conclusions : Through this study, we suggest that oriental medical treatments and Chuna treatment were effective to cure patients with pain and LOM subsequent to scapular fracture.

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