• Title/Summary/Keyword: STEP-NC

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The Implement of 2-Step Motion Control Loop and Look Ahead Algorithm for a High Speed Machining (고속가공을 위한 2단계 모션 제어 루프와 선독 알고리즘의 구현)

  • 이철수;이제필
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.6
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    • pp.71-81
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    • 2000
  • This paper describers a look ahead algorithm of PC-NC(personal computer numerical control). The algorithm is based on acceleration/deceleration before interpolation which doesn\`t include a command error and determines a feedrate value at the end point of each block(or start point of each block). The algorithm is represented as following; 1) calculating two maximum arrival feedrates(F$_1$,F$_2$) by an acceleration value, a command feedrate, and the distance of a NC block, 2) getting a tangent feedrate (F$_3$) of the adjacent blocks, 3) choosing a minimum value among these three feedrates, and 4) setting the value to a feedrate of a start point of the next block(or a end point of the previous block). The proposed look ahead algorithm was implemented and tested by using a commercial TROS(real time operation system) on the MS-Windows NT 4.0 in a PC platform. For interfacing to a machine, a counter board, a DAC board and a DIO board were used. The result of the algorithm increased a machining precision and a machining speed in many short blocks.

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An Efficient Triangulation Algorithm for Trimmed NURBS Surfaces (트림된 NURBS 곡면의 효율적인 삼각화 알고리즘)

  • 정재호;박준영
    • Korean Journal of Computational Design and Engineering
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    • v.5 no.2
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    • pp.144-154
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    • 2000
  • We propose an algorithm for obtaining a triangular approximation of a trimmed NLRBS surface. Triangular approximation is used in the pre-processing step of many applications such as RP(Rapid Prototyping), NC(Numerical Control) and FEA(Finite Element Analysis), etc. The algorithm minimizes the number of triangular elements within tolerance and generates a valid triangular mesh for STL file and NC tool path generation. In the algorithm, a subdivision method is used. Since a patch is a basic element of triangular mesh creation, boundary curves of a patch are divided into line segments and the division of curves is applied for the interior of the surface. That is, boundary curves are subdivided into line segments and two end points of each line segment are propagated to the interior of the surface. For the case of a trimmed surface, triangulation is carried out using a model space information. The algorithm is superior because the number of elements can be controlled as the curvature of the surface varies and it generates the triangular mesh in a trimmed region efficiently. To verify the efficiency, the algorithm was implemented and tested for several 3D objects bounded by NURBS surfaces.

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A New Item Recommendation Procedure Using Preference Boundary

  • Kim, Hyea-Kyeong;Jang, Moon-Kyoung;Kim, Jae-Kyeong;Cho, Yoon-Ho
    • Asia pacific journal of information systems
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    • v.20 no.1
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    • pp.81-99
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    • 2010
  • Lately, in consumers' markets the number of new items is rapidly increasing at an overwhelming rate while consumers have limited access to information about those new products in making a sensible, well-informed purchase. Therefore, item providers and customers need a system which recommends right items to right customers. Also, whenever new items are released, for instance, the recommender system specializing in new items can help item providers locate and identify potential customers. Currently, new items are being added to an existing system without being specially noted to consumers, making it difficult for consumers to identify and evaluate new products introduced in the markets. Most of previous approaches for recommender systems have to rely on the usage history of customers. For new items, this content-based (CB) approach is simply not available for the system to recommend those new items to potential consumers. Although collaborative filtering (CF) approach is not directly applicable to solve the new item problem, it would be a good idea to use the basic principle of CF which identifies similar customers, i,e. neighbors, and recommend items to those customers who have liked the similar items in the past. This research aims to suggest a hybrid recommendation procedure based on the preference boundary of target customer. We suggest the hybrid recommendation procedure using the preference boundary in the feature space for recommending new items only. The basic principle is that if a new item belongs within the preference boundary of a target customer, then it is evaluated to be preferred by the customer. Customers' preferences and characteristics of items including new items are represented in a feature space, and the scope or boundary of the target customer's preference is extended to those of neighbors'. The new item recommendation procedure consists of three steps. The first step is analyzing the profile of items, which are represented as k-dimensional feature values. The second step is to determine the representative point of the target customer's preference boundary, the centroid, based on a personal information set. To determine the centroid of preference boundary of a target customer, three algorithms are developed in this research: one is using the centroid of a target customer only (TC), the other is using centroid of a (dummy) big target customer that is composed of a target customer and his/her neighbors (BC), and another is using centroids of a target customer and his/her neighbors (NC). The third step is to determine the range of the preference boundary, the radius. The suggested algorithm Is using the average distance (AD) between the centroid and all purchased items. We test whether the CF-based approach to determine the centroid of the preference boundary improves the recommendation quality or not. For this purpose, we develop two hybrid algorithms, BC and NC, which use neighbors when deciding centroid of the preference boundary. To test the validity of hybrid algorithms, BC and NC, we developed CB-algorithm, TC, which uses target customers only. We measured effectiveness scores of suggested algorithms and compared them through a series of experiments with a set of real mobile image transaction data. We spilt the period between 1st June 2004 and 31st July and the period between 1st August and 31st August 2004 as a training set and a test set, respectively. The training set Is used to make the preference boundary, and the test set is used to evaluate the performance of the suggested hybrid recommendation procedure. The main aim of this research Is to compare the hybrid recommendation algorithm with the CB algorithm. To evaluate the performance of each algorithm, we compare the purchased new item list in test period with the recommended item list which is recommended by suggested algorithms. So we employ the evaluation metric to hit the ratio for evaluating our algorithms. The hit ratio is defined as the ratio of the hit set size to the recommended set size. The hit set size means the number of success of recommendations in our experiment, and the test set size means the number of purchased items during the test period. Experimental test result shows the hit ratio of BC and NC is bigger than that of TC. This means using neighbors Is more effective to recommend new items. That is hybrid algorithm using CF is more effective when recommending to consumers new items than the algorithm using only CB. The reason of the smaller hit ratio of BC than that of NC is that BC is defined as a dummy or virtual customer who purchased all items of target customers' and neighbors'. That is centroid of BC often shifts from that of TC, so it tends to reflect skewed characters of target customer. So the recommendation algorithm using NC shows the best hit ratio, because NC has sufficient information about target customers and their neighbors without damaging the information about the target customers.

Direct position tracking method for non-circular signals with distributed passive arrays via first-order approximation

  • Jinke Cao;Xiaofei Zhang;Honghao Hao
    • ETRI Journal
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    • v.46 no.3
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    • pp.421-431
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    • 2024
  • In this study, a direct position tracking method for non-circular (NC) signals using distributed passive arrays is proposed. First, we calculate the initial positions of sources using a direct position determination (DPD) approach; next, we transform the tracking into a compensation problem. The offsets of the adjacent time positions are calculated using a first-order Taylor expansion. The fusion calculation of the noise subspace is performed according to the NC characteristics. Because the proposed method uses the signal information from the previous iteration, it can realize automatic data associations. Compared with traditional DPD and two-step localization methods, our novel process has lower computational complexity and provides higher accuracy. Moreover, its performance is better than that of the traditional tracking methods. Numerous simulation results support the superiority of our proposed method.

Antibacterial Effects of Silver Fluoride and Difluorosilane-based Varnish on Streptococcus mutans (불화은과 다이플루오르실란 함유 바니쉬의 Streptococcus mutans에 대한 항균 효과)

  • Hyunseok, Lee;Soyoun, An
    • Journal of the korean academy of Pediatric Dentistry
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    • v.49 no.4
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    • pp.497-504
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    • 2022
  • The purpose of this study is to evaluate the antibacterial effects of two liquid fluoride materials on Streptococcus mutans (S. mutans). Riva star aquaTM (SDI, Bayswater, Australia), which consists of silver fluoride (AgF, step 1) and potassium iodide (KI, step 2), and Fluor protector® (FP; Ivoclar Vivadent, Liechtenstein) were used for experimental groups. Experimental groups were divided into 4 groups : AgF, KI, AgF + KI and FP. For the positive control (PC) group, ampicillin was used, and the negative control group (NC) did not receive any additional treatment. Each group was divided into 30 and 50 µL groups by volume of liquid and applied to flat-coated S. mutans. The diameter of the zone of inhibition was measured. The PC and AgF groups showed larger diameters than other materials (p < 0.05), and the AgF group showed no significant difference from the PC group in the 50 µL group (p > 0.05). The FP group showed larger diameters than the AgF + KI group in the 30 µL (p = 0.009). The KI group did not show significant difference from the NC group (p > 0.05). AgF is comparable to ampicillin in antibacterial effects on S. mutans, and better than FP.

A study on Knowledge based-processing of information to shape cutting (형상 가공 정보의 지식 베이스 처리에 관한 연구)

  • 김희중;조우승;정재현
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1995.10a
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    • pp.970-973
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    • 1995
  • The proposal of this paper is the constructing of knowledge database with manufacturing information. This database contains characteristics of workpiece materials, cutting tools, NC machines, manufacturing processes, and work conditions. And all shape in the system are feature models such base plate, step, hole, pocket, boss, and slot. These information generate a final decision for machining process by the expert system.

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Development of PC Controled Automatic Cutting System (PC를 이용한 철판 자동절단시스템 개발)

  • Kim, Sang-Hun;Chung, Kyung-Ryul
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.1
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    • pp.29-37
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    • 1996
  • In this study, PC controlled CNC automatic cutting system is developed. Technological introduction of the control process and the computer programming has made possible not only the automatic control for cutting processing unit but also the easy-to-use graphic software that enables the cutting process. This program involves shape part drawing and amendment, pattern reading and saving, reading Autocad file, nesting process, kerf compensation, automatic cutting path generation, NC file conversion and motor control. Software is devided into 3 modules for easy work. First step enables drawing, amendment and pattern making, followed by automatic nesting and cutting path generation with kerf compensation. In the final step, drawing data is transmitted for the resulting automatic cutting processes. This software would be applicated in gas cutting and textile cutting so that it improves the productivity of cutting process.

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Efficient modeling of die-face shapes for stamping automobile outer panels (차체 판넬의 가공 제작을 위한 금형형상의 효율적 모델링)

  • 박종천;이건우;전기찬
    • Journal of the korean Society of Automotive Engineers
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    • v.15 no.3
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    • pp.96-110
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    • 1993
  • A procedure has been developed so that a die-face for stamping automobile outer panels can be design and modelled efficiently. The procedure is composed of four parts each of which corresponds to modeling major components of a die-face, i.e. tipped product, blankholder, draw beads, and step draw. The modeling techniques developed specifically for die-face design enable a designer to generate the shape of a die-face quickly with the minimum input, and the resulting models can be used in FEM analysis and NC tool path generation. This will lead to the reductions in lead time and manhours required for the design and manufacture of the stamping dies.

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Design of Noncircular Gears for Wire EDM (비원형 기어의 와이어 방전가공을 위한 설계)

  • Lee, Sung-Chul
    • Tribology and Lubricants
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    • v.24 no.5
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    • pp.221-227
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    • 2008
  • This paper presents a step-by-step design of noncircular gears. From the diagram of angular velocity ratio of a noncircular gear pair, the pitch curves of the two mating gears are determined, and the perimeter of the pitch curve has been divided into equal-length segments by the number of teeth. A master tooth profile, which is a composite curve of circular arcs that represents involute, has been introduced. A noncircular gear pair has been designed by imposing the master tooth on the divided points of the pitch curve, and a full fillet has been achieved between neighbour teeth. Thus, the whole profile of the noncircular gear is a composite curve of arcs only, and consequently NC codes for wire EDM can be easily generated.

A Case Study on the Development of a Curriculum by using NCS (NCS를 활용한 교육과정 개발 사례 연구)

  • Baek, Jinwook
    • Journal of Creative Information Culture
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    • v.7 no.4
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    • pp.217-224
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    • 2021
  • Because of the development of the 4th industrial technology such as artificial intelligence and the corona situation, the recent university society is rapidly changing. As the college entrance exam environment is also getting seriously difficult, departments and majors are rapidly changing at the university. Therefore, the department of the university needs a curriculum for new majors or convergence majors according to the internal and external environment of the department. However, it is a very difficult and time-consuming task to develop such a curriculum accurately. This paper proposes a curriculum development method and an application case using the National Competency Standards(NCS). The curriculum development method proposed in this paper consists of the traditional three-step method, namely, analysis, design, and development, and NCS is used in each step. This proposed method focused on reducing the time of curriculum development, and an example of curriculum development is presented for the usefulness of the proposed method.