• Korean Journal of Computational Design and Engineering
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• v.9 no.1
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• pp.51-61
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• 2004

Mechanical parts are often grouped into part families based on the similarity of their shapes, to support efficient manufacturing process planning and design modification. The 2-part sequence papers present similarity assessment techniques to support part family classification for machined parts. These exploit the multiple feature decompositions obtained by the feature recognition method using convex decomposition. Convex decomposition provides a hierarchical volumetric representation of a part, organized in an outside-in hierarchy. It provides local accessibility directions, which supports abstract and qualitative similarity assessment. It is converted to a Form Feature Decomposition (FFD), which represents a part using form features intrinsic to the shape of the part. This supports abstract and qualitative similarity assessment using positive feature volumes.. FFD is converted to Negative Feature Decomposition (NFD), which represents a part as a base component and negative machining features. This supports a detailed, quantitative similarity assessment technique that measures the similarity between machined parts and associated machining processes implied by two parts' NFDs. Features of the NFD are organized into branch groups to capture the NFD hierarchy and feature interrelations. Branch groups of two parts' NFDs are matched to obtain pairs, and then features within each pair of branch groups are compared, exploiting feature type, size, machining direction, and other information relevant to machining processes. This paper, the second one of the two companion papers, describes the similarity assessment method using NFD.

• Korean Journal of Computational Design and Engineering
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• v.9 no.1
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• pp.44-50
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• 2004

Mechanical parts are often grouped into part families based on the similarity of their shapes, to support efficient manufacturing process planning and design modification. The 2-part sequence papers present similarity assessment techniques to support part family classification for machined parts. These exploit the multiple feature decompositions obtained by the feature recognition method using convex decomposition. Convex decomposition provides a hierarchical volumetric representation of a part, organized in an outside-in hierarchy. It provides local accessibility directions, which supports abstract and qualitative similarity assessment. It is converted to a Form Feature Decomposition (FFD), which represents a part using form features intrinsic to the shape of the part. This supports abstract and qualitative similarity assessment using positive feature volumes. FFD is converted to Negative Feature Decomposition (NFD), which represents a part as a base component and negative machining features. This supports a detailed, quantitative similarity assessment technique that measures the similarity between machined parts and associated machining processes implied by two parts' NFDs. Features of the NFD are organized into branch groups to capture the NFD hierarchy and feature interrelations. Branch groups of two parts' NFDs are matched to obtain pairs, and then features within each pair of branch groups are compared, exploiting feature type, size, machining direction, and other information relevant to machining processes. This paper, the first one of the two companion papers, describes the similarity assessment methods using convex decomposition and FFD.

• Journal of the Korean Society of Costume
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• v.54 no.5
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• pp.109-123
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• 2004

The purpose of this study is to examine features of parts of Jikryung and relations among the features. Results of the study can be described as follows. 1. The short front and long rear of Jikryung was changed into the long front and long rear of the dress in the late 16th century. Kalgit of quasi-square style as double collar was changed into that of common collar in the late 16th century and then into common semi-circle collar in the early 17th century, when double Sup was also changed Into single Sup. Narrow sleeves of Jikryung were replaced by bean chaff-shaped in the late 16th century and then by wide ones in the early period of the next century. The shape of the side hem of Jikryung was changed from rectangle into trapezoid in the early 17th century Triangle-shaped Moo was changed into trapezoid-shaped one in the late 16th century and then again into triangle in the late 17th century 2. Changes in shapes of the parts of Jikryung were made with them correlated. The collar of Jikryung saw change in its form from double to common as its width was reduced. Double Sup was changed into single one and the narrow, short coat string into the long one as Jikryung became a dress needing less adjustment. The sleeves widened as the length of whajang increased. The side hem of Jikryung saw change in its shape from rectangular to trapezoidal one as its position was changed. Trapezoidal Moo was replaced by triangular one as the sleeve of Jikryung was changed in shape. 3. Changes in shapes of the parts of Jikryung influenced the aesthetic beauty of the dress itself In its first period, Jikryung was simple with long, slim silhouettes. In its second period, the dress was rich with increased volume. Finally in its third period, the dress was characterized by the harmony of simpleness and richness.

• Korean Management Science Review
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• v.29 no.1
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• pp.101-114
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• 2012

The demand for naval spare parts is intermittent and erratic. This feature, referred to as non-normal demand, makes forecasting difficult. Hierarchical forecasting using an aggregated time series can be more reliable to predict non-normal demand than direct forecasting. In practice the performance of hierarchical forecasting is not always superior to direct forecasting. The relative performance of the alternative forecasting methods depends on the demand features. This paper analyses the influence of the demand features on the performance of the alternative forecasting methods that use hierarchical and direct forecasting. Among various demand features variability, kurtosis, skewness and equipment groups are shown to significantly influence on the performance of the alternative forecasting methods.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.1933-1947
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• 1991

The synthesis of supplementary features of injection molded parts has been done empirically, since it requires profound knowledge about the features' moldability and causal effects on the properties of the part, which are not available to designers through current CAD systems. RIBBER is a knowledge module which contains knowledge to permit non-experts as well as mold design experts to generate acceptable supplementary features of injection molded parts. A knowledge-based CAD system is constructed by adding the knowledge module, RIBBER, for mold feature synthesis and appropriate CAE programs for mold design analysis to an existing geometric modeler in order to provide designers, at the initial design stage, with comprehensive process knowledge-based CAD system is a new tool which enables the concurrent design and CIM with integrated and balanced design decisions at the initial design stage of injection molding.

• Korean Journal of Computational Design and Engineering
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• v.11 no.4
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• pp.315-325
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• 2006

It is very often necessary to search for similar parts during designing a new product because its parts are often easily designed by modifying existing similar parts. In this way, the design time and cost can be reduced. Thus it would be nice to have an efficient similarity comparison algorithm that can be used anytime in the design process. There have been many approaches to compare shape similarity between two solids. In this paper, two parts represented in B-Rep is compared in two steps: one for overall appearances and the other for detail features. In the first step, geometric information is used in low level of detail for easy and fast pre-classification by the overall appearance. In the second step, feature information is used to compare the detail shape in high level of detail to find more similar design. To realize the idea above, a multi resolution algorithm is proposed so that a given solid is described by an overall appearance in a low resolution and by detail features in high resolution. Using this multi-resolution representation, parts can be compared based on the overall appearance first so that the number of parts to be compared in high resolution is reduced, and then detail features are investigated to retrieve the most similar part. In this way, computational time can be reduced by the fast classification in the first step while reliability can be preserved by detail comparison in the second step.

• Journal of Korean Society for Quality Management
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• v.24 no.1
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• pp.126-136
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• 1996

In multi-item production system, GT(Group Technology) is used effectively in order to cluster various parts into groups. GT is based on clustering parts which have similar features, and these features are classified into two properties, namely crisp(quantitative) feature and fuzzy(qualitative) feature. Especially, many difficult problems are often faced that have to evaluate the properties of parts with the crisp and fuzzy feature together. As the basis of determining the similarity of inter-parts, in this method, one aggregate value is calculated on each part. However, because the above aggregate value is only gained from simple additive weighted sum, there is one problem in this method that has been handled the combination effect of inter-parts. For these reasons, in this paper, a proposed method is suggested for representing combination effect in order to cluster parts that have crisp and fuzzy properties into groups using ${\lambda}$-fuzzy measure and fuzzy integral.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.896-900
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• 1992

This paper presents a comprehensive methodology of automatic feature recognition for rotational parts. The parts of interest are rotational without deviation. In stage one, IGES formatted daa of 2D engineering drawings are transformed into three independent graphs through upperhalf profile. In stage two, recursive evaluations are made to recognize features and relevant information is acquired. Finally,an example is evaluated to demonstrate the recognition power of the developed algorithm for rotational features.

• Journal of Intelligence and Information Systems
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• v.2 no.1
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• pp.45-58
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• 1996

This paper describes an a, pp.oach to recognizing composite features of prismatic parts. AAG (Attribute Adjacency Graph) is adopted as the basis of describing basic feature, but it is extended to enhance the expressive power of AAG by adding face type, angles between faces and normal vectors. Our a, pp.oach is called Extended AAG (EAAG). To simplify the recognition procedure, feature classification tree is built using the graph types of EEA and the number of EAD's. Algorithms to find open faces and dimensions of features are exemplified and used in decomposing composite feature. The processing sequence of recognized features is automatically determined during the decomposition process of composite features.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1991.04a
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• pp.309-315
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• 1991

This paper presents a method for automatic part feature recognition from the database of AutoCAD system for automatic process planning input. The parts considered in this study are primastic parts composed of faces perpendicular to the X, Y, Z axes and the types of features considered are through steps, blind steps, through slots, blind slots, and pockets. Features are recognized by using the concept of convex points and concave points. The software program is coded by using Turbo Pascal on the IBM PC/AT.