• 한국정밀공학회지
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• 제11권6호
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• pp.65-74
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• 1994

Various substructure synthesis methods, such as component mode synthesis, building block analysis and reduced impedance method, are studied for the determination of vibration characteristics of plate problems. Comparisons are made for each methods in terms of accuracy and computational efficiency. Following conclusions are made from the results of computer simulations and experiments. i) The computation time of component mode synthesis is much shorter than that of whole structure analysis. The natural frequencies of lower modes obtained from component mode synthesis are almost same as those obtained from whole structure analysis, but in higher modes the differences between those two methods are increases. ii) The transfer function obtained from building block analysis is same as that obtained from the finite element method. iii) Same transfer functions can be obtained by the reduced impedance method. The computation time of reduced impedance mathod is shorter that that of general finite element method, but for the solutions in broad frequency band it requires long calculation time.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(4)
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• pp.151-154
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• 2001

In this Paper, a new harmonic imaging technique is proposed and evaluated experimentally. In the proposed method, a weighted chin signal with a hanning window is transmitted. The RF samples obtained on each array element are individually compressed by correlating with the reference signal defined as the 2nd harmonic (2f0) component of a transmitted chirp signal generated in a square-law system. The proposed method uses the compressed 2f0 component to form an image, for which the crosscorrelation term with f0 component should be suppressed below at least -60dB. After experiment, the 6dB pulse width and peak sidelobe level of the compressed 2f0 component were 0.7us and -60dB, respectively. This result shows that the proposed method can successfully eliminate the f0 component with a single transmit-receive event and therefore is more efficient than the conventional pulse inversion (PI) method in terms of frame rate. We also observed that the 2nd harmonic compont starts to decrease for source pressure higher than 210kPa in water, which implies that SNR of the 2nd harmonic imaging using short pulses cnanot be incresed beyond a certain limit.

• 정보처리학회논문지D
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• 제9D권1호
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• pp.91-102
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• 2002

사용자의 요구사항 변경에 따른 반영, 빠른 시스템 구축, 유지 보수 단계의 효율적인 시스템 관리, 소프트웨어의 수정 용이성, 저렴한 비용 등은 컴포넌트 기반 시스템 구축이 필수적인 사항으로 여겨지고 있다. 이러한 컴포넌트 기반 시스템 구축을 위한 기존의 컴포넌트 개발 방법론은 컴포넌트 식별을 위하여 객체를 추출하는 부분이 비효율적이고 시스템 컴포넌트를 추출하기 위한 방법이 제시되어 있지 않다. 또한 시스템의 전체 도메인을 중심으로 비즈니스 컴포넌트 식별을 위한 절차와 방법만을 제시하고 있다. 그리고 컴포넌트 식별을 위하여 대부분 개발자의 직관과 경험에 의존하는 문제점이 있다. 따라서 본 논문에서는 객체를 추출하는 비효율적인 부분을 개선하기 위하여 요구 사항 분석단계부터 객체를 추출하는 단계까지 RUP(Rational Unified Process)를 적용한다. 또한 시스템 컴포넌트를 식별하기 위한 방법과 절차를 제안하고 시스템의 전체 도메인을 중심으로 비즈니스 컴포넌트를 식별하는 것이 아니라 추출된 시스템 컴포넌트를 중심으로 비즈니스 컴포넌트를 추출한다. 개발자의 직관과 경험에 의존하여 컴포넌트를 식별하는 문제점을 보완하기 위하여 응집척도와 결합철도를 제안하고 적용한다. 본 논문에서 제안하는 컴포넌트 식별 방법은 객체 식별의 용이성, 컴포넌트의 기능적 재사용성, 추적성 그리고 컴포넌트의 독립성을 중심으로 좀 더 효율적으로 컴포넌트를 식별한다.

• Steel and Composite Structures
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• 제18권5호
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• pp.1305-1330
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• 2015

The successful application of the component-based approach - widely used to model structural joints - requires knowledge of the mechanical properties of the constitutive joint components, including an appropriate assembly procedure to derive the joint properties. This paper presents a component-method model for a structural joint component that is located in the tension zone of blind-bolted connections to concrete-filled tubular steel profiles. The model relates to the response of blind-bolts with headed anchors under monotonic loading, and the blind-bolt is termed the "Extended Hollo-bolt". Experimental data is used to develop the model, with the data being collected in a manner such that constitutive models were characterised for the principal elements which contribute to the global deformability of the connector. The model, based on a system of spring elements, incorporates pre-load and deformation from various parts of the blind-bolt: (i) the internal bolt elongation; (ii) the connector's expanding sleeves element; and (iii) the connector's mechanical anchorage element. The characteristics of these elements are determined on the basis of piecewise functions, accounting for basic geometrical and mechanical properties such as the strength of the concrete applied to the tube, the connection clamping length, and the size and class of the blind-bolt's internal bolt. An assembly process is then detailed to establish the model for the elastic and inelastic behaviour of the component. Comparisons of model predictions with experimental data show that the proposed model can predict with sufficient accuracy the response of the component. The model furthers the development of a full and detailed design method for an original connection technology.

• 반도체디스플레이기술학회지
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• 제23권2호
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• pp.1-5
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• 2024

In the electronics industry, a lot of research and development is being conducted on electronic component supply, component alignment and insertion, and automation of soldering on the back side of the PCB for automatic PCB assembly. Additionally, as the use of electronic components increases in the automotive component field, there is a growing need to automate the alignment and insertion of components with leads such as transistors, coils, and fuses on PCB. In response to these demands, the types of PCB and parts used have been more various, and as this industrial trend, the quantity and placement of automation equipment that supplies, aligns, inserts, and solders components has become important in PCB manufacturing plants. It is also necessary to reduce the pre-setting time before using each automation equipment. In this study, we propose a method in which a vision system recognizes the type of component and simultaneously corrects alignment errors during the process of aligning and inserting various types of electronic components. The proposed method is effective in manufacturing various types of PCBs by minimizing the amount of automatic equipment inserted after alignment with the component supply device and omitting the preset process depending on the type of component supplied. Also the advantage of the proposed method is that the structure of the existing automatic insertion machine can be easily modified and utilized without major changes.

• Earthquakes and Structures
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• 제16권5호
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• pp.575-588
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• 2019

Seismic design method based on bearing capacity has been widely adopted in building codes around the world, however, damage and collapse state of structure under strong earthquake can not be reflected accurately. This paper aims to present a deformation-based seismic design method based on the research of RC component deformation index limit, which combines with the feature of Chinese building codes. In the proposed method, building performance is divided into five levels and components are classified into three types according to their importance. Five specific design approaches, namely, "Elastic Design", "Unyielding Design", "Limit Design", "Minimum Section Design" and "Deformation Assessment", are defined and used in different scenarios to prove whether the seismic performance objectives are attained. For the components which exhibit ductile failure, deformation of components under strong earthquake are obtained quantitatively in order to identify the damage state of the components. For the components which present brittle shear failure, their performance is guaranteed by bearing capacity. As a case study, seismic design of an extremely irregular twin-tower high rise building was carried out according to the proposed method. The results evidenced that the damage and anti-collapse ability of structure were estimated and controlled by both deformation and bearing capacity.

• 시스템엔지니어링학술지
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• 제16권1호
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• pp.84-97
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• 2020

This paper aims to develop an optimized inventory management method for safety critical Instrument and Control (I&C) components. In this regard, the paper focuses on estimating the consumption rate of I&C components using demand forecasting methods. The target component for this paper is the Foxboro SPEC-200 controller. This component was chosen because it has highest consumption rate among the safety critical I&C components in Korean OPR-1000 NPPs. Three analytical methods were chosen in order to develop the demand forecasting methods; Poisson, Generalized Linear Model (GLM) and Bootstrapping. The results show that the GLM gives better accuracy than the other analytical methods. This is because the GLM considers the maintenance level of the component by discriminating between corrective and preventive.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2002년도 춘계공동학술대회
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• pp.272-279
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• 2002

A common task in assembly modeling is the determination of the position and orientation of a set of components by solving the spatial relationships between them. Assembly models could be constructed at various levels of abstraction. They could be classified into component or geometry-level assembly models. The geometry-level assembly design approach using mating constraints such as against and fits is widely used in the commercial modelers, but it may be very tedious in some cases fur designer. In this paper, we propose a new method to construct an assembly model at the component-level by extracting joint mating features from the kinematics constraints specified between components. The assembly model constructed using the proposed method includes hierarchical and relational assembly models, component/sub-assembly positions and degrees of freedom information. The proposed method is more intuitive and natural way of assembly design and it guarantees the topological robustness of assembly modification such as component replacement and modification.

• 말소리와 음성과학
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• 제1권1호
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• pp.69-73
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• 2009

This paper proposes an efficient global covariance-based principal component analysis (GCPCA) for speaker identification. Principal component analysis (PCA) is a feature extraction method which reduces the dimension of the feature vectors and the correlation among the feature vectors by projecting the original feature space into a small subspace through a transformation. However, it requires a larger amount of training data when performing PCA to find the eigenvalue and eigenvector matrix using the full covariance matrix by each speaker. The proposed method first calculates the global covariance matrix using training data of all speakers. It then finds the eigenvalue matrix and the corresponding eigenvector matrix from the global covariance matrix. Compared to conventional PCA and Gaussian mixture model (GMM) methods, the proposed method shows better performance while requiring less storage space and complexity in speaker identification.

• 응용통계연구
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• 제33권1호
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• pp.61-74
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• 2020

심볼릭 자료 중 하나인 구간형 자료는 모든 관측값에서 단일 값이 아닌 구간을 값으로 취하며, 관측값 내에 변동이 존재한다는 특징을 갖는다. 주성분 분석은 자료의 분산을 최대로 설명하여 자료의 차원을 축소하는 방법이므로 구간형 자료의 주성분 분석은 관측값 간의 분산 뿐만 아니라 관측값 내의 분산 역시 설명하여야 한다. 본 논문에서는 구간형 자료의 세 가지 주성분 분석법을 소개하고자 한다. 또한 기존의 분위수 방법에서 균일분포를 사용하는 것이 아니라 구간의 중심점 부근이 좀 더 많은 정보를 가지고 있는 것으로 보고 절단정규분포를 사용하는 방법을 제안하였다. 모의실험과 OECD 관련 실제 통계 자료를 통하여 각 방법의 결과를 비교해 보았다. 마지막으로 분위수 방법의 경우 화살표 표현법을 통해 주성분 산점도를 그리고 분위수들의 위치와 분포를 확인하였다.