• 전자통신동향분석
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• 제4권1호
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• pp.93-117
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• 1989

Computational Geometry is concerned with the design and analysis of computational algorithms which solve geometry problems. Geometry problems have a large number of applications areas such as pattern recognition, image processing, computer graphics, VLSI design and statistics since they involve inherently geometric problems for which efficient algorithms have to be developed. Several parallel algorithms, based on various parallel computation models, have been proposed for solving geometric problems. We review the current status of the parallel algorithms in computational geometry.

• 한국CDE학회논문집
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• 제11권3호
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• pp.164-171
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• 2006

As collaborative design and configuration design are of increasing importance in product development, it becomes essential to exchange the feature and parametric CAD models among participants. A history-based parametric method has been proposed and implemented. But each translator which exchanges the feature and parametric information tends to be heavy because to implement duplicated functions such as the identification of the selected geometries, mapping between features which have different attributes. Furthermore. because the history-based parametric translator uses the procedural model as the neutral format, which is the XML macro file, the history-based parametric translators need a geometric modeling kernel to generate an internal explicit geometric model. To ease the problem, we implemented a shared integration platform, the TransCAD. The TransCAD separates translators from the XML macro files. The translators for various CAD systems need to communicate with only the TransCAD. To support the communication with the TransCAD, we exposed the functions of the TransCAD by using the Automation APIs, which is developed by Microsoft. The Automation APIs of the TransCAD consist of the part modeling functions, the data extraction functions, and the utility functions. Each translator uses these functions to translate a parametric CAD model from the sending CAD system into the XML format, or from the in format into the model of the receiving CAD system This paper introduces what the TransCAD is and how it works for the exchange of the feature and parametric models.

• 전자공학회논문지
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• 제51권11호
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• pp.57-65
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• 2014

본 논문에서는 전류 모드 논리 회로들로 구현되는 고속 디지털 회로의 설계를 가능하게 하는 수식 기반의 자동화 설계 틀을 제시하고자 한다. 제안된 매크로 모델은 제약 기반의 최적화를 가능하게 하는 geometric programming에 호환 가능하며 이를 통해 시스템 레벨에서의 전력 소모 최적화를 가능하게 한다. 제안된 수식 기반의 자동화 설계 틀은 전류 모드 논리 회로고속 디지털 회로의 대표적인 종류 중 하나인 시리얼 링크 전송회로에 적용 되었다. 이를 통해, 사용자 정의 설계 사양에 따라 최적화를 수행하게 된다. 제안된 수식 기반의 자동화 설계 틀은 CMOS 45nm 와 90nm 각각 적용 되어 시리얼 링크 설계의 전력 소모 최적화를 수행하였으며, 이를 통해 각각의 공정 노드에 존재하는 최적의 전력 효율을 가지는 시리얼 링크의 데이터 스피드를 얻어 낼 수 있다.

• Steel and Composite Structures
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• 제6권6호
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• pp.531-555
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• 2006

H-shaped welded steel column members are fabricated by welding together pre-cut flanges and the web. Modern fabricators are increasingly using plasma-cutting technique instead of traditional flame cutting. Different fabrication techniques result in different degrees of geometric imperfections and residual stresses, which can have considerable influence on the strength of steel columns. This paper presents the experimental investigation based temperature profiles, geometric imperfections, and built-in residual stresses in plasma cut-welded H-shaped steel column members and in similar flame cut-welded H-shaped steel columns. Temperature measurements were taken during and immediately after the cutting operations and the welding operations. The geometric imperfections were established at closely spaced grid locations on the original plates, after cutting plates into plate strips, and after welding plate strips into columns. Geometric imperfections associated with plasma cut element and members were found to be less than those of the corresponding elements and members made by flame cutting. The "Method of Section" technique was used to establish the residual stresses in the plate, plate strip, and in the welded columns. Higher residual stress values were observed in flame cut-welded columns. Models for idealized residual stress distributions for plasma cut and flame cut welded sections have been proposed.

• Structural Engineering and Mechanics
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• 제90권1호
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• pp.97-106
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• 2024

This paper presents a significant contribution to aided design by conducting an analytical examination of geometric links with the aim of establishing criteria for assessing an analogy measure of the extrinsic geometric and kinematic characteristics of the Variable Compression Ratio (VCR) engine with a Geared Mechanism (GBCM) in comparison to the existing Fixed Compression Ratio (FCR) engine with a Standard-Reciprocating Crankshaft configuration. Employing a mechanical approach grounded in projective computational methods, a parametric study has been conducted to analyze the kinematic behavior and geometric transformations of the moving links. The findings indicate that in order to ensure equivalent extrinsic behavior and maintain consistent input-output performance between both engine types, precise adjustments of intrinsic geometric parameters are necessary. Specifically, for a VCR configuration compared to an FCR configuration, regardless of compression ratio and gearwheel radius, for the same crankshaft ratios and stroke lengths, it is imperative to halve lengths of connecting rods, and crank radius. These insights underscore the importance of meticulous parameter adjustment in achieving comparable performance across different engine configurations, offering valuable implications for design optimization.

• 한국디자인학회:학술대회논문집
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• 한국디자인학회 2004년도 추계 학술발표대회 논문집
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• pp.194-195
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• 2004

• 한국도로학회논문집
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• 제14권6호
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• pp.159-165
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• 2012

PURPOSES : The lack of details of guidelines on how to install the Chicane for traffic calming leads the practical difference across the calming areas, so the benefits expected from these facilities are not hardly observed. In this context, this study analysed the relationship between the geometric design alternatives of Chicane with the dynamic behaviour of vehicles in terms of speed and trajectory. METHODS : The study analysed vehicle dynamic behaviour using dynamic analysis program Auto-Turn under various geometric conditions of Chicane. RESULTS : This study suggested the design alternatives of Chicane using terms such as "longitudinal displacement value", "lateral displacement value", etc. which are defined in the study. The suggested combination set is fulfilling the desired or target speed of vehicles and clearance between vehicle and roadside at the same time. CONCLUSIONS : The results from this study can be applied to install Chicane corresponding to the local condition where target speed is 30km/h. The study showed the design alternatives of chicane corresponding to the given road cross-sectional design and clearance to roadside for passenger cars and light truck respectively.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권1호
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• pp.75-87
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• 2012

A design paradigm using sequential geometric programming is presented to accurately design CMOS op amps with BSIM3. It is based on new adaptive modeling of transistor parameters through the operating point simulation. This has low modeling cost as well as great simplicity and high accuracy. The short-channel dc, high-frequency small-signal, and short-channel noise models are used to characterize the physical behavior of submicron devices. For low-power and low-voltage design, this paradigm is extended to op amps operating in the subthreshold region. Since the biasing and modeling errors are less than 0.25%, the characteristics of the op amps well match simulation results. In addition, small dependency of design results on initial values indicates that a designed op amp may be close to the global optimum. Finally, the design paradigm is illustrated by optimizing CMOS op amps with accurate transfer function.

• 한국정밀공학회지
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• 제15권10호
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• pp.172-179
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• 1998

To quickly determine the effect of the substitute component on the machine's performance is very important in the design and manufacturing processes. And minimizing machine cost and maximizing machine quality mandate predictability of machine accuracy. In this study, in order to evaluate the effects of the component's geometric errors and dimensions on the machining accuracy of gantry-type 5-axis machining centers, a geometric error analysis and virtual manufacturing system are developed based on the mathematical model for the shape generation motion of machine tool considering the component's geometric errors and dimensions, the solid modeling techniques and so on.

• 한국전자파학회논문지
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• 제26권1호
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• pp.71-80
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• 2015

한정된 배터리 용량으로 장시간 모바일 시스템을 구동시키기 위하여 저전력 설계에 대한 요구가 높아지면서 PMIC(Power Management IC)의 핵심 부분인 LDO(Low Drop-Out) 레귤레이터의 설계에 대한 관심이 증가하고 있다. 본 논문에서는 Dongbu HiTek $0.5{\mu}m$ BCDMOS 공정을 이용하여 최적화 기법 중 하나인 기하 프로그래밍(Geometric Programming: GP)을 통해 외부 커패시터가 없는 LDO 레귤레이터의 성능을 최적화하였다. 계수가 양수인 단항식 (monomial)으로 모델링된 트랜지스터의 특성 파라미터들을 이용하여 안정도(stability)와 PSR(Power-Supply Rejection)과 같은 LDO 레귤레이터의 특성을 기하 프로그래밍(Geometric Programming: GP)에 적용 가능한 형태로 유도하였다. 위상 마진(phase margin)과 PSR 모델은 시뮬레이션 결과와 비교하였을 때 각각 평균 9.3 %와 13.1 %의 오차를 보였다. 제안한 모델을 사용하여 PSR 제약 조건이 바뀔 경우, 자동화된 회로 설계를 수행하였고, 모델의 정확도를 검증하였다. 본 논문에서 유도된 안정도와 PSR 모델을 이용하면 회로의 목표 성능이 변화하더라도 부가적인 설계 시간을 줄이면서 목표 성능을 가진 회로를 재설계하는 것이 가능할 것이다.