• 한국경영과학회지
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• 제29권2호
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• pp.59-75
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• 2004

Recommendation is a personalized information filtering technology to help customers find which products they would like to purchase. Collaborative filtering works by matching customer preferences to other customers in making recommendations. But collaborative filtering based recommendations have two major limitations, sparsity and scalability. To overcome these problems we suggest using adjusted product hierarchy, grain. This methodology focuses on dimensionality reduction and uses a marketer's specific knowledge or experience to improve recommendation quality. The qualify of recommendations using each grain is compared with others by several experimentations. Experiments present that the usage of a grain holds the promise of allowing CF-based recommendations to scale to large data sets and at the same time produces better recommendations. In addition. our methodology is proved to save the computation time by 3∼4 times compared with collaborative filtering.

• KIEE International Transaction on Systems and Control
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• 제12D권1호
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• pp.33-38
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• 2002

In this paper, the infinite time optimal regulation problem for weakly coupled bilinear systems with quadratic performance criteria is obtained by a sequence of algebraic Lyapunov equations. This is the new approach is based on the successive approximation. In particular, the order reduction is achieved by using suitable state transformation so that the original Lyapunov equations are decomposed into the reduced-order local Lyapunov equations. The proposed algorithms not only solve optimal control problems in the weakly coupled bilinear system but also reduce the computation time. This paper also includes an example to demonstrate the procedures.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.1999-2001
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• 2001

The infinite time optimum to regulate the problem of weakly coupled bilinear systems with a quadratic performance criterion is obtained by a sequence of algebraic Lyapunov equations. The new approach is based on the successive approximations. In particular, the order reduction is achieved by using suitable state transformation so that the original Lyapunov equations are decomposed into the reduced-order local Lyapunov equations. The proposed algorithms not only solve optimal control problems in the weakly coupled bilinear system but also reduce the computation time. This paper also includes an example to demonstrate the procedures.

• 대한산업공학회지
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• 제18권1호
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• pp.63-80
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• 1992

The concept of rapid prototyping intended for a significant reduction in cost and lead time becomes even more practical with the recent development of various equipments to make the concept concrete. For the purpose of real application of commercially available SLA(stereolithography apparatus), this paper is intended to develop the standard conversion procedure from CAD data to the input data for SLA. While the procedure presented in this paper is based on CAD system "CATIA" and SLA of 3D systems, Inc., which are being used in authors' company DAEWOO Motor Co., Ltd., the basic concept of this paper can be applied to any other CAD systems and machines of using stereolithography process. The algorithm presented in this paper is classified into two stages-node sampling and triangulation. First of all, point data are sampled through the node sampling procedure, and then these are triangulated so that the input data for SLA operation is finally generated. The suggested method is devised in a way to meet the input requirements of SLA and more importantly consume less computation time and generate less number of input data for SLA.

• 디지털산업정보학회논문지
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• 제18권1호
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• pp.1-9
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• 2022

Galois field arithmetic is important in error correcting codes and public-key cryptography schemes. Hardware realization of these schemes requires an efficient implementation of Galois field arithmetic operations. Multiplication is the main finite field operation and designing efficient multiplier can clearly affect the performance of compute-intensive applications. Diverse algorithms and hardware architectures are presented in the literature for hardware realization of Galois field multiplication to acquire a reduction in time and area. This paper presents a low complexity semi-systolic multiplier to facilitate parallel processing by partitioning Montgomery modular multiplication (MMM) into two independent and identical units and two-level systolic computation scheme. Analytical results indicate that the proposed multiplier achieves lower area-time (AT) complexity compared to related multipliers. Moreover, the proposed method has regularity, concurrency, and modularity, and thus is well suited for VLSI implementation. It can be applied as a core circuit for multiplication and division/exponentiation.

• Wind and Structures
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• 제22권3호
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• pp.349-368
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• 2016

A preconditioning technique is presented for a simultaneous solution to wind-membrane interaction. In the simultaneous equations, a linear elastic model was employed to deal with the fluid-structure data transfer at the interface. A Lagrange multiplier was introduced to impose the specified boundary conditions at the interface and strongly coupled simultaneous equations are derived after space and time discretization. An initial linear elastic model preconditioner and modified one were derived by treating the linearized elastic model equation as a saddle point problem, respectively. Accordingly, initial and modified fluid-structure interaction (FSI) preconditioner for the simultaneous equations were derived based on the initial and modified linear elastic model preconditioners, respectively. Wind-membrane interaction analysis by the proposed preconditioners, for two and three dimensional membranous structures respectively, was performed. Comparison was made between the performance of initial and modified preconditioners by comparing parameters such as iteration numbers, relative residuals and convergence in FSI computation. The results show that the proposed preconditioning technique greatly improves calculation accuracy and efficiency. The priority of the modified FSI preconditioner is verified. The proposed preconditioning technique provides an efficient solution procedure and paves the way for practical application of simultaneous solution for wind-structure interaction computation.

• 한국음향학회지
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• 제19권1호
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• pp.67-72
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• 2000

본 논문에서는 오염된 입력음성을 보상하는 방법들 중 신호편의제거 알고리듬을 근간으로 하여 환경에 독립적이고, 연산량을 최소화하며, 그리고 기존의 인식시스템에 쉽게 적용시킬 수 있는 새로운 보상 알고리듬을 개발하였다. 이를 위하여 기존의 신호편의제거 알고리듬에 대하여 여러 개의 바이어스를 동시에 사용하는 알고리듬과 코드북을 부분적으로 검색하는 알고리듬을 추가로 제안하였다. 실험 결과, 본 논문에서 제안한 두 가지 알고리듬을 복합하여 적용한 경우, 기존 알고리듬에 비하여 약 1/8정도로 연산량을 감소시킬 수 있었으며, 보상 후의 인식률도 기존 신호편의제거 알고리듬의 77.58%에서 81.32%로 향상되었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권12호
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• pp.3166-3179
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• 2013

A pre-processing system for adaptive noise removal is proposed based on the principle of identifying and filtering object regions and background regions. Human perception of images depends on bright, well-focused object regions; these regions can be treated with the best filters, while simpler filters can be applied to other regions to reduce overall computational complexity. In the proposed method, bright region segmentation is performed, followed by segmentation of object and background regions. Noise in dark, background, and object regions is then removed by the median, fast bilateral, and bilateral filters, respectively. Simulations show that the proposed algorithm is much faster than and performs nearly as well as the bilateral filter (which is considered a powerful noise removal algorithm); it reduces computation time by 19.4 % while reducing PSNR by only 1.57 % relative to bilateral filtering. Thus, the proposed algorithm remarkably reduces computation while maintaining accuracy.

• 한국산업정보학회논문지
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• 제7권4호
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• pp.17-21
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• 2002

적응신호처리 분야에서 LMS알고리즘은 수식이 간단하고, 적은 계산량으로 인해 널리 사용되고 있지만, 시간영역의 적응알고리즘은 입력신호의 고유치 분포폭이 넓게 분포할 때는 수렴속도가 느려지는 단점이 있다. 또한 알고리즘의 성능을 좌우하는 고정된 적응상수를 적절하게 선택해야만 알고리즘이 수렴할 수 있다. 이런 문제점을 개선하기 위하여 본 논문에서는 시간영역의 적응알고리즘을 변환영역인 웨이블렛 변환에서 적응알고리즘을 적용한다. 그리고 안정되고 빠른 수렴을 위해 고정된 적응상수를 오차신호의 순시치 절대값에 비례하여 각 반복구간마다 변화시키는 가변스텝사이즈를 갖는 웨이블렛 기반 고속적응알고리즘을 제안, 적응잡음제거기에 적용하여 기존의 알고리즘과 비교하여 그 성능이 우수함을 입증하였다.

• 대한전자공학회논문지SD
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• 제45권9호
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• pp.65-70
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• 2008

FIR 필터에서 곱셈기는 대부분의 면적을 차지한다. FIR 필터의 설계시 개별적인 곱셈기 대신 Common Subexpression Elimination(CSE) 알고리즘을 이용하여 덧셈만으로 곱셈기를 구현할 수 있다. CSE방식은 곱셈을 이용하지 않기 때문에 보다 작은 면적으로 필터를 구현할 수 있으나 덧셈에서 발생하는 캐리의 긴 전파 시간으로 인하여 필터 연산시간이 길어지는 단점이 있다. 특히 더해지는 항의 쉬프트가 클수록 부호 확장이 많아지며 부호확장에 의해 덧셈의 면적이 커지고 계산 시간이 길어진다. 본 논문에서는 CSE 알고리즘에서 부호 확장 부분을 제거하는 방법을 제안하며 제안한 알고리즘을 이용하여 주어진 예제를 삼성 0.35u 공정으로 설계하였을 때 기존 설계 방법 보다 면적, 속도, 파워소모에서 각각 17%, 31%, 12% 의 이득이 있음을 보인다.