• 제목/요약/키워드: 3D-fitting model

검색결과 148건 처리시간 0.03초

PT를 이용한 파이프내면 육성용접부 표면결함 진단시스템 개발에 관한 연구 (A Study on the Development of Diagnosing System of Defects on Surface of Inner Overlay Welding of Long Pipes using Liquid Penetrant Test)

  • 노태정
    • 한국산학기술학회논문지
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    • 제19권10호
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    • pp.121-127
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    • 2018
  • 액체침투탐상법(PT)을 이용한 직경 1 m, 길이 6 m의 초장대형 파이프내면 육성용접부의 표면결함 진단시스템을 개발하였다. 우선 CATIA를 사용하여 주요 유닛 및 PT machine 전체를 3D 모델링하였으며, 이를 구조강도 및 변형 해석에 사용하였고 또한 각 유닛의 동작 간섭현상을 체크하여 2차원 제작도면 생성으로 제작에도 사용하였다. ANSYS를 사용하여 구조강도 해석 및 변형 해석한 결과, 최대 등가응력은 44.901 MPa 발생하였고, 이는 PT machine의 재질인 SS400의 항복인장강도 200 MPa 보다 작으므로 안전하다고 판단되며, 또한 최대 변형은 0.15 mm 발생하였고, 이는 하중이 제거되면 원래대로 돌아간다고 판단된다. 개발된 장비의 성능을 검증하기 위하여 공작물의 최대이동속도 7.2 m/min., 최대회전속도 9 rpm, 반복위치정밀도 1.2 mm, 검사속도 $1.65m^2/min$. 등을 확인하였으며, 이 모든 검사 항목은 개발 목표치를 만족하였다. ASME SEC. V&VIII의 방법에 따라 육성용접층의 균열, 기공, 인더컷 등의 표면결함 유무를 확인하기 위하여 개발한 PT 자동검사시스템을 사용하여 PT검사를 실시한 결과, 표면층의 결함은 관찰되지 않았다. 부가적으로 육성용접부를 평가하기 위하여 ASTM G48-11의 방법으로 Ferric Chloride pitting test에 따라 육성용접층의 부식시험을 실시한 결과 weight loss는 $0.3g/m^2$으로 만족하였으며, 또한 ASTM A751-14의 방법에 따라 육성용접층의 화학성분을 분석 결과 모든 성분이 규격을 만족하였다.

Study of random characteristics of fluctuating wind loads on ultra-large cooling towers in full construction process

  • Ke, S.T.;Xu, L.;Ge, Y.J.
    • Wind and Structures
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    • 제26권4호
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    • pp.191-204
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    • 2018
  • This article presents a study of the largest-ever (height = 220 m) cooling tower using the large eddy simulation (LES) method. Information about fluid fields around the tower and 3D aerodynamic time history in full construction process were obtained, and the wind pressure distribution along the entire tower predicted by the developed model was compared with standard curves and measured curves to validate the effectiveness of the simulating method. Based on that, average wind pressure distribution and characteristics of fluid fields in the construction process of ultra-large cooling tower were investigated. The characteristics of fluid fields in full construction process and their working principles were investigated based on wind speeds and vorticities under different construction conditions. Then, time domain characteristics of ultra-large cooling towers in full construction process, including fluctuating wind loads, extreme wind loads, lift and drag coefficients, and relationship of measuring points, were studied and fitting formula of extreme wind load as a function of height was developed based on the nonlinear least square method. Additionally, the frequency domain characteristics of wind loads on the constructing tower, including wind pressure power spectrum at typical measuring points, lift and drag power spectrum, circumferential correlations between typical measuring points, and vertical correlations of lift coefficient and drag coefficient, were analyzed. The results revealed that the random characteristics of fluctuating wind loads, as well as corresponding extreme wind pressure and power spectra curves, varied significantly and in real time with the height of the constructing tower. This study provides references for design of wind loads during construction period of ultra-large cooling towers.

광산란 거친표면의 고정밀 삼차원 형상 측정을 위한 점회절 간섭계 (Point-diffraction interferometer for 3-D profile measurement of light scattering rough surfaces)

  • 김병창;이호재;김승우
    • 한국광학회지
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    • 제14권5호
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    • pp.504-508
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    • 2003
  • 최근 전자산업계에 새롭게 널리 생산되는 마이크로 전자부품들은 왜곡이 최소화된 정밀한 외관 형상을 갖도록 제조되고 관리되지만, 측정 대상의 표면이 가시광 영역에서 광산란되는 특징을 가짐으로 인해, 기존의 피죠나 마이켈슨 형태의 비교간섭법으로는 고정밀의 삼차원 형상측정이 용이하지 아니하였다. 본 논문에서는 광섬유를 이용한 새로운 개념의 점회절 간섭계를 제안하고, 이를 광산란 거친표면의 대표적인 제품인 칩패키지와 실리콘 웨이퍼의 삼차원 형상 측정에 적용하였다. 측정결과 66 mm 측정영역에서 측정 형상오차 PV(peak-to-valley value) 5.6 $\mu\textrm{m}$, 분산값($\sigma$) 1.5 $\mu\textrm{m}$를 획득함으로써 기존의 비교 간섭 측정법에 비해 더욱 향상된 측정 정밀도를 획득하였다.

양에서 시행한 이동작동기 형태(MOVING ACTUATOR TYPE) 인공심장의 삽입실험 (Experimental Implantation of Moving Actuator Type Total Artificial Heart in Sheep)

  • 김원곤
    • Journal of Chest Surgery
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    • 제28권6호
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    • pp.533-541
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    • 1995
  • We recently developed a new model of moving actuator type totally implantable artificial heart[TIAH , based on the reverse position of the aortic and pulmonary conduits. This concept was proposed by one of surgeons in our team[Joon-Ryang Rho, M.D. to facilitate anatomical fitting of TIAHs. The moving actuator type electromechanical TIAH consisted of the left and right blood sacs, and the moving actuator including a motor. The inverted umbrella type polyurethane valves were used in the blood pumps. The aortic conduit was positioned anterior to the pulmonary conduit, which was the opposite relation to the conventional configuration of other total artificial hearts. We also adapted slip-in connectors for the aortic and pulmonary conduits. Two sheep , weighing 60-69 kg, were used for implantation. After small cervical incision and trans-sternal bilateral thoracotomy, cardiopulmonary bypass [CPB was administered using an American Optical 5-head pump and a membrane oxygenator[Univox-IC, Bentley . The anterior and posterior vena cavae were drained separately for venous return. An arterial return cannula was inserted into the right common carotid artery. During CPB, almost all of the ventricular myocardium was excised down to the atrioventricular groove and the artificial heart was implanted. We achieved 3-day survival in the first sheep and 2-day survival in the second. The day after operation the first sheep was successfully extubated and the second sheep was weaned from a respirator with good condition. After extubation, the first sheep walked around in the cage and fed herself. Serial laboratory and hemodynamic examinations were done during the experiments. In both sheep, pulmonary dysfunction was gradually developed, which was accompanied by acute renal failure. The animals were sacrificed and autopsy was done. Unexpected pregnnacy was incidentally found in both sheep. To our knowledge this is the first report of significant survival cases in the orthotopic implantation of electric TIAH using sheep.

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한국 연근해에서 어획된 주요 12어종의 75 kHz에 대한 음향 반사 강도의 체장 의존성 (Fish length dependence of acoustic target strength for 12 dominant fish species caught in the Korean waters at 75 kHz)

  • 이대재
    • 수산해양기술연구
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    • 제41권4호
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    • pp.296-305
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    • 2005
  • Acoustic target strength (TS) of 12 commercially important fish species caught in the Korean waters had been investigated and their results were presented. Laboratory measurements of target strength on 12 dominant fish species were carried out at a frequencies of 75 kHz by single beam method under the controlled condition of the water tank with the 241 samples of dead and live fishes. The target strength pattern on individual fish of each species was measured as a function of tilt angle, ranging from $-45^{\circ}$ (head down aspect) to $45^{\circ}$ (head up aspect) in $0.2^{\circ}$ intervals, and the averaged target strength was estimated by assuming the tilt angle distribution as N ($-5.0^{\circ}$, $^15.0{\circ}$). The 75 to fish length relationship for each species was independently derived by a least - squares fitting procedure. Also, a linear regression analysis for all species was performed to reduce the data to a set of empirical equations showing the variation of target strength to fish length and fish species. An empirical model for fish target strength(TS, dB) averaged over the dorsal aspect of 158 fishes of 7 species and which spans the fish length(L, m) to wavelength(${\lambda}$, m) ratio between 6.2 and 21.3 was derived: TS: 27.03 Log(L)-7.7Log(${\kanbda}$)-17.21, ($r^2$=0.59).

감정예측모형의 성과개선을 위한 Support Vector Regression 응용 (Application of Support Vector Regression for Improving the Performance of the Emotion Prediction Model)

  • 김성진;유은정;정민규;김재경;안현철
    • 지능정보연구
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    • 제18권3호
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    • pp.185-202
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    • 2012
  • 오늘날 정보사회에서는 정보에 대한 가치를 인식하고, 이를 위한 정보의 활용과 수집이 중요해지고 있다. 얼굴 표정은 그림 하나가 수천개의 단어를 표현할 수 있듯이 수천 개의 정보를 지니고 있다. 이에 주목하여 최근 얼굴 표정을 통해 사람의 감정을 판단하여 지능형 서비스를 제공하기 위한 시도가 MIT Media Lab을 필두로 활발하게 이루어지고 있다. 전통적으로 기존 연구에서는 인공신경망, 중회귀분석 등의 기법을 통해 사람의 감정을 판단하는 연구가 이루어져 왔다. 하지만 중회귀모형은 예측 정확도가 떨어지고, 인공신경망은 성능은 뛰어나지만 기법 자체가 지닌 과적합화 문제로 인해 한계를 지닌다. 본 연구는 사람들의 자극에 대한 반응으로서 나타나는 얼굴 표정을 통해 감정을 추론해내는 지능형 모형을 개발하는 것을 목표로 한다. 기존 얼굴 표정을 통한 지능형 감정판단모형을 개선하기 위하여, Support Vector Regression(이하 SVR) 기법을 적용하는 새로운 모형을 제시한다. SVR은 기존 Support Vector Machine이 가진 뛰어난 예측 능력을 바탕으로, 회귀문제 영역을 해결하기 위해 확장된 것이다. 본 연구의 제안 모형의 목적은 사람의 얼굴 표정으로부터 쾌/불쾌 수준 그리고 몰입도를 판단할 수 있도록 설계되는 것이다. 모형 구축을 위해 사람들에게 적절한 자극영상을 제공했을 때 나타나는 얼굴 반응들을 수집했고, 이를 기반으로 얼굴 특징점을 도출 및 보정하였다. 이후 전처리 과정을 통해 통계적 유의변수를 추출 후 학습용과 검증용 데이터로 구분하여 SVR 모형을 통해 학습시키고, 평가되도록 하였다. 다수의 일반인들을 대상으로 수집된 실제 데이터셋을 기반으로 제안모형을 적용해 본 결과, 매우 우수한 예측 정확도를 보임을 확인할 수 있었다. 아울러, 중회귀분석이나 인공신경망 기법과 비교했을 때에도 본 연구에서 제안한 SVR 모형이 쾌/불쾌 수준 및 몰입도 모두에서 더 우수한 예측성과를 보임을 확인할 수 있었다. 이는 얼굴 표정에 기반한 감정판단모형으로서 SVR이 상당히 효과적인 수단이 될 수 있다는 점을 알 수 있었다.

Oxolinic acid의 경구투여, 주사 및 약욕에 따른 넙치, Paralichthys olivaceus 체내 약물동태학적 특성 (Pharmacokinetics of oxolinic acid in cultured olive flounder Paralichthys olivaceus by oral administration, injection and dipping)

  • 정승희;최동림;김진우;조미라;지보영;서정수
    • 한국어병학회지
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    • 제22권2호
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    • pp.125-135
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    • 2009
  • Oxolonic acid (OA)를 넙치(평균체중 90 g)에 1회 경구투여(15, 30 및 60 ㎎/㎏ body weight), 1회 복강주사(10 및 20 ㎎/㎏ body weight) 및 1시간동안 약욕(30 및 50 ppm)한 다음, 경시적(3시간-144시간)인 혈장내 OA의 잔류농도를 분석하였다. 15, 30 및 60 ㎎/㎏ 농도로 경구투여한 모든 시험구에서 투여 10~15시간째 각각 1.92, 2.45 및 3.72 $\mu{g}/m\ell$로 최대혈중농도를 나타내었다. 10 및 20 ㎎/㎏ 농도로 복강주사한 경우, 투여 10시간째 각각 4.1 및 4.8 $\mu{g}/m\ell$로 최대혈중농도를 나타내었다. 약욕한 시험구의 경우, 30 및 50 ppm 시험구는 각각 투여 5-30시간째 0.22 및 0.38 $\mu{g}/m\ell$로 최대혈중농도를 나타내었다. OA의 투여방법에 따른 넙치 체내 약물 혈중농도 측정결과를 바탕으로 one- compartment model로 WinNonlin program을 이용하여 OA의 흡수, 배설, 반감기 등 약물동태학적 매개변수 (parameter)를 조사하였다. 15, 30 및 60 ㎎/㎏을 경구투여한 경우, 혈장농도-시간곡선하 면적 (AUC)은 각각 70.93, 120.0 및 141.86 $\mu{g}$ $h/m\ell$, 혈중최고농도의 도달시간($T_{max}$)은 16.22, 20.39 및 17.33 h, 혈중최고농도 ($C_{max}$)는 1.61, 2.40 및 3.01 $\mu{g}/m\ell$로 계산되었다. 10 및 20 ㎎/㎏을 복강주사한 경우, 혈장농도-시간곡선하 면적(AUC)은 각 각 184.7 및 315.92 $\mu{g}$ $h/m\ell$, 혈중최고농도의 도달시간($T_{max}$)은 5.91 및 6.26 h, 혈중최고농도($C_{max}$)는 4.19 및 4.45 $\mu{g}/m\ell$로 계산되었다. 30 및 50ppm으로 약욕한 경우, 혈장농도-시간곡선하 면적 (AUC)은 각각 17.58 및 21.69 $\mu{g}$ $h/m\ell$, 혈중 최고농도의 도달시간($T_{max}$)은 19.08 및 31.43 h, 혈중최고농도($C_{max}$)는 0.22 및 0.25 $\mu{g}/m\ell$로 계산되었다.

다양한 다분류 SVM을 적용한 기업채권평가 (Corporate Bond Rating Using Various Multiclass Support Vector Machines)

  • 안현철;김경재
    • Asia pacific journal of information systems
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    • 제19권2호
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    • pp.157-178
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    • 2009
  • Corporate credit rating is a very important factor in the market for corporate debt. Information concerning corporate operations is often disseminated to market participants through the changes in credit ratings that are published by professional rating agencies, such as Standard and Poor's (S&P) and Moody's Investor Service. Since these agencies generally require a large fee for the service, and the periodically provided ratings sometimes do not reflect the default risk of the company at the time, it may be advantageous for bond-market participants to be able to classify credit ratings before the agencies actually publish them. As a result, it is very important for companies (especially, financial companies) to develop a proper model of credit rating. From a technical perspective, the credit rating constitutes a typical, multiclass, classification problem because rating agencies generally have ten or more categories of ratings. For example, S&P's ratings range from AAA for the highest-quality bonds to D for the lowest-quality bonds. The professional rating agencies emphasize the importance of analysts' subjective judgments in the determination of credit ratings. However, in practice, a mathematical model that uses the financial variables of companies plays an important role in determining credit ratings, since it is convenient to apply and cost efficient. These financial variables include the ratios that represent a company's leverage status, liquidity status, and profitability status. Several statistical and artificial intelligence (AI) techniques have been applied as tools for predicting credit ratings. Among them, artificial neural networks are most prevalent in the area of finance because of their broad applicability to many business problems and their preeminent ability to adapt. However, artificial neural networks also have many defects, including the difficulty in determining the values of the control parameters and the number of processing elements in the layer as well as the risk of over-fitting. Of late, because of their robustness and high accuracy, support vector machines (SVMs) have become popular as a solution for problems with generating accurate prediction. An SVM's solution may be globally optimal because SVMs seek to minimize structural risk. On the other hand, artificial neural network models may tend to find locally optimal solutions because they seek to minimize empirical risk. In addition, no parameters need to be tuned in SVMs, barring the upper bound for non-separable cases in linear SVMs. Since SVMs were originally devised for binary classification, however they are not intrinsically geared for multiclass classifications as in credit ratings. Thus, researchers have tried to extend the original SVM to multiclass classification. Hitherto, a variety of techniques to extend standard SVMs to multiclass SVMs (MSVMs) has been proposed in the literature Only a few types of MSVM are, however, tested using prior studies that apply MSVMs to credit ratings studies. In this study, we examined six different techniques of MSVMs: (1) One-Against-One, (2) One-Against-AIL (3) DAGSVM, (4) ECOC, (5) Method of Weston and Watkins, and (6) Method of Crammer and Singer. In addition, we examined the prediction accuracy of some modified version of conventional MSVM techniques. To find the most appropriate technique of MSVMs for corporate bond rating, we applied all the techniques of MSVMs to a real-world case of credit rating in Korea. The best application is in corporate bond rating, which is the most frequently studied area of credit rating for specific debt issues or other financial obligations. For our study the research data were collected from National Information and Credit Evaluation, Inc., a major bond-rating company in Korea. The data set is comprised of the bond-ratings for the year 2002 and various financial variables for 1,295 companies from the manufacturing industry in Korea. We compared the results of these techniques with one another, and with those of traditional methods for credit ratings, such as multiple discriminant analysis (MDA), multinomial logistic regression (MLOGIT), and artificial neural networks (ANNs). As a result, we found that DAGSVM with an ordered list was the best approach for the prediction of bond rating. In addition, we found that the modified version of ECOC approach can yield higher prediction accuracy for the cases showing clear patterns.