• 제목/요약/키워드: numerical methods

검색결과 5,297건 처리시간 0.035초

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

  • 선민영;이성범;이기열;문병영
    • Journal of Advanced Marine Engineering and Technology
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    • 제38권9호
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    • pp.1075-1080
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    • 2014
  • 본 연구는 5MW급 해상풍력 하부구조물개발에 있어 설계에 필요한 다양한 해양환경 조건에 대하여 높은 안정성 확보가 요구되는 해상용 풍력발전 하부구조물과 관련, 구조물의 설계방법을 제시하고 그 안정성을 고찰하여 관련 기술 분야에 기여함을 목표로 한다. 특히, 5MW급 해상풍력발전 시스템에 대해 시험영역에서 큰 바람의 방향이 지속되고 있는 동안에 동시에 발달된 파도의 계산에 대한 정보를 제공한다. 그러므로 바람의 영역과 접근하는 파동 행열간의 관련성을 검토하여 강도, 방향 그리고 시간의 이동성을 계산할 수 있음을 확인하였다. 쇄파에서의 국부적인 압력분포를 물리적인 모델링과 수치적 모델링을 통해 조사하는 것이 가능하다. 해상 풍력 에너지 변환장치의 지지구조물들에 대해 최근 적용된 구조 및 피로에 대한 평가는 일반 설계규칙에 근거했다. 5MW 해상풍력 하부구조물은 제약조건이 많아 단일구조로 취급하는데 이는 생산에서 높은 안전계수를 고려해야함을 의미한다.

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

  • 이무연;이동연;김용찬
    • 대한기계학회논문집B
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    • 제31권6호
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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.

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

  • 황선민;송복희;윤한경
    • 한국콘텐츠학회논문지
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    • 제11권9호
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    • pp.1-8
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    • 2011
  • 본 연구는 질량-스프링 모델 기반의 직물 모델에서 질점의 움직임을 분석하여 실시간 직물 애니메이션이 가능한 퍼지 추론 기법을 제안한다. 지금까지 직물과 같은 탄성체를 표현하기 위한 많은 기법들은 질량-스프링 모델을 사용하였다. 직물은 다수의 질량과 스프링의 조합으로 구성되어 변형 가능한 면을 이루게되고, 면의 움직임은 운동법칙을 기반으로 수치적분을 통해 계산될 수 있다. 제안된 방법과 동일한 직물구조에서 Explicit 오일러 방법은 ${\Delta}t$ > 0.01 일 경우 불안정성 문제가 나타났으며, Implicit 오일러 방법은 ${\Delta}t$ = 0.03 에서도 애니메이션이 생성되지만 많은 양의 선형 시스템을 계산해야 하는 단점을 가지고 있어서 실시간 처리에 부적합하다. 본 연구는 질량-스프링 모델에서 질점의 움직임을 계산하기 위하여 ${\Delta}t$ = 0.03을 가지면서도 실시간 처리가 가능한 방법을 제안한다.

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

  • 박정용
    • 한국콘텐츠학회논문지
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    • 제10권11호
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    • pp.1-9
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    • 2010
  • 경험을 통한 지식의 습득이 단순한 기호나 수식을 통한 지식의 습득과 비교해서 보다 안정적이고 명료하게 학습자에게 정보를 전달한다. 컴퓨터 기반의 교육용 시스템은 가상현실기술, 지능형 교육 시스템, 개념의 시각화기술, 시뮬레이션 기반 시스템, 미세한 세계(MicroWorld)를 이용한 형태로 연구되어지고 있다. 본 논문에서는 교육용 시스템의 여러 형태 중에서 시뮬레이션 기반으로 물리법칙을 2D로 시각화하여 학습자에게 교육할 수 있는 방법을 제안한다. 특히 물리법칙 중 중력의 법칙을 시뮬레이션하여 확인함으로써 간접적 경험을 통하여 보다 명료하게 지식을 습득한다. 시뮬레이션을 통한 명확한 지식 전달을 위해서 본 논문에서는 실시간적인 물리법칙의 시각화, 가상 이상 현상(virtual anomaly), 물리법칙의 시각화를 시뮬레이션한다. 그리고 학습자는 이러한 방법들을 통해서 효율적이고 효과적인 지식습득이 가능함을 보인다.

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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    • 제59권2호
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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.

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

  • 편종근;박우선;윤정방
    • 대한토목학회논문집
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    • 제7권3호
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    • pp.223-228
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    • 1987
  • 본 논문에서는 Tension Leg Platform(TLP)에 작용하는 파랑하중을 간단한 Morison 방정식을 이용하여 효율적으로 산정할 수 있는 방법에 대해서 연구하였다. 본 방법에서는 MacCamy-Fuchs 산란파이론에 기초를 둔 파동력 감소계수를 도입하여 파의 산란효과를 근사적으로 고려하였으며, Morison 방정식 상에서는 무시되는 연직기둥의 바닥에 작용하는 수직력을 이 면에서의 동압력과 수직방향의 부가질량에 관련된 관성력으로 산정하여 고려하였다. 수치해석은 1000 ft 수심에 위치한 가상적인 구조물에 $0^{\circ}$$45^{\circ}$로 입사하는 파에 대하여 전술한 방법 및 이론적으로 보다 정확한 산란파이론에 의한 방법을 사용하여 수행하였으며, TLP 운동 및 tether의 상단 인장력의 전달함수(RAO)를 구하여 비교 검토하였다.

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

  • 권혁준;김주원;류기준;김호준;이명종
    • 척추신경추나의학회지
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    • 제4권2호
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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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견갑골 골절 후 견관절 통증 및 관절가동범위 제한을 동반한 환자에 추나와 한방 치료를 시행한 치험 2례 (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)

  • 이경무;임상훈;윤대연;김순중;정수현
    • 척추신경추나의학회지
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    • 제4권2호
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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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추나요법을 적용한 한방복합치료로 호전된 요추 추간판 탈출증으로 인한 비구조적 척추측만증 5례: 증례보고 (Five Cases of Nonstructural Scoliosis with Lumbar Herniated Intervertebral Disc Treated by Complex Korean Medicine Treatment with Chuna Manual Therapy: Case Report)

  • 남궁진;황보경;신원빈;최효정;백혜경;이윤하;최동주
    • 척추신경추나의학회지
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    • 제15권1호
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    • pp.121-134
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    • 2020
  • Objectives : This case report describes the management of five patients suffering from nonstructural scoliosis with lumbar herniated intervertebral disc all treated with complex Korean medicine treatment. Methods : Five patients were hospitalized and treated with herbal medicine, acupuncture, pharmacopuncture, cupping, and Chuna manual therapy. Patients were assessed for Numerical Rating Scale (NRS), Oswestry Disability Index (ODI), EuroQol-FiveDimensions (EQ-5D), and Cobb's angle. Results : In all patients, NRS, ODI, and Cobb's angle decreased, while the EQ-5D score increased. Conclusions : As seen in these five cases, complex Korean medicine treatment with Chuna manual therapy has effects on the management of nonstructural scoliosis.

화담청화탕이 acetic acid로 유발된 흰쥐 위궤양 점막의 내분비세포와 점액의 조직화학적 변화 (The Changes of Mucin and Endocrine cells of Mucosa of Acetic Acid-Induced Gastric Ulcer after Administration of Whadamcheongwha-tang Extract in Rat)

  • 강경래;육상원;고형근;이광규;이창현
    • 동의생리병리학회지
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    • 제16권6호
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    • pp.1170-1176
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    • 2002
  • We examined the effects of Whadamcheongwha-tang(WDCWT) extract on the acetic-acid induced antigastric ulcer in rats. These experiments investigated the numerical changes of gastrin and histamine secreting cells of the gastric mucosa by immunohistochemical method, and the changes of mucin of gastric mucosa by PAS-AB stain methods after the oral administration of WDCWT extract(1.0ml/day) and omeprazole(0.2mg/day) for 1, 3 and 6 weeks. The result are as follows; 1. When WDCWT extract was administrated for 1, 3, 6 weeks, in result, gastrin secreting cells in gastric mucosa were increased compared to the control group. 2. When WDCWT extract was administrated for 1, 3, 6 weeks, in result, the density of immunoreactive gastrin cells was increased compare to the control group. 3. When WDCWT extract was administrated for 1, 3, 6 weeks, in results, the changs of mucosal thickness stained by PAS/PAS-AB was increased compared to the control group. 4. When WDCWT extract was administrated for 1, 3, 6 weeks, in results, the density of PAS stain was decreased compare to control group, but density of AB stain was increased compare to control group. The results suggest that WDCWT extract inhibits a gastric acid secretion in rat gastric mucosa, and is useful in the treatment of the hyperacidity and gastric ulcer.