• 제목/요약/키워드: Forming error

검색결과 184건 처리시간 0.023초

SBC와 블럭 적응 양자화를 이용한 가정용 디지탈 VCR 영상 압축 알고리듬 (An Image Data Compression Algorithm for a Home-Use Digital VCR Using SBC with Block-Adaptive Quantization)

  • 김주희;서정태;박용철;이제형;윤대희
    • 전자공학회논문지B
    • /
    • 제31B권9호
    • /
    • pp.124-132
    • /
    • 1994
  • An image data compression method for a digital VCR must satisfy special requirements such as high speed playback. various edting capabilities and error concealment to provide immunity to tape dropouts. Taking these requirements requirements into consideration, this paper proposes a new interframe subband coding algorithm for a digital VCR. In the proposed method, continuous input images are fist partitioned into four frequency bands. The lowest frequency subband is coded with 3-D block adaptive quantization that removes the level redundancy within each level. The other higher frequency subbands are coded by an intraframe coding method using the property of the human visual system. To keep reasonable image quality in high speed palyback, a segment forming method in the frequency domaing is also proposed Computer simulation results demonstrate that the proposed algorithm has the potential of achieving virtually lossless compression in normal play and produces an image with less mosaic errors in high speed play.

  • PDF

유세포 분석기를 이용한 대장균 검출에 관한 연구 (Detection of Escherichia coli Using Flow Cytometry)

  • 김지혜;박상원;조영식
    • 한국환경과학회지
    • /
    • 제26권1호
    • /
    • pp.11-21
    • /
    • 2017
  • In this study, bacterial growth was assessed by flow cytometry analysis of fluorescent probes-stained bacteria. Flow cytometry has many advantages of rapid analytical time, a low standard deviation, and highly sensitive detection of live and Dead E.coli over colony forming assay. When untreated bacteria were stained by using Thiazole Orange (TO) and Propidium Iodide (PI), double staining had a short analytical time as compared with that of single staining while its error rate was similar to that of single staining. Through double staining experiments, it was determined that optimal concentrations for TO and PI staining were 420 nM and $9.6{\mu}M$, respectively.

일본내 연구동향 (6편중 제4편) (State-of-the-art of the multi-scale analysis of advanced composite materials by homogenization method)

  • Takano, Naoki
    • Composites Research
    • /
    • 제15권5호
    • /
    • pp.44-52
    • /
    • 2002
  • To study numerically the mechanical behaviors of advanced composite materials considering the microscopic phenomena as well as the macroscopic properties and behaviors, a multi-scale modeling and analysis by the mathematical homogenization method with the help of the finite element method(FEM) are reviewed. The hierarchical modeling strategy and the formulation are briefly described first to give some idea of the multi-scale framework. The latter half of this article focuses on the verification of the multi-scale analysis by the homogenization method in its applications to real advanced materials. The first example is the verification of the predicted macroscopic(homogenized) properties based on the microstructure of porous ceramics. In spite of the complexity of the random microstructure, the error between the predicted and the measured values was only 1%. Next, two applications to the process simulation of fiber reinforced polymer matrix composites are presented. The permeability characteristics are evaluated for sheared weave fabrics for resin transfer molding(RTM) simulation, and the thermoforming of FRTP sheet is analyzed considering the large deformation of the knit structure during the deep-draw forming was verified by comparison with the experimental results.

손잡이 일체형 PET 용기 제작을 위한 블로우 성형에 대한 수치적 연구 (A numerical study on blow molding for manufacturing PET bottle consisted of single body)

  • 김종덕;고영배;김홍렬;권창오
    • Design & Manufacturing
    • /
    • 제2권3호
    • /
    • pp.22-27
    • /
    • 2008
  • Forming of PET bottle was performed by injection-stretch blow molding. Blow molding is process of contacting the dies with air of materials by pressing. In this paper, the aim was to improve reliability of technical stabilization for the PET bottle that is last productive product and process technology which was able to do maximization by a preform performance enhancement of the uniform thickness that took temperature and a characteristic of materials. Preform design and dies manufacture were conducted using injection blow molding analysis results. Therefore thickness error of 5% for PET bottle can be obtained in this paper.

  • PDF

냉간 단조용 전방압출금형의 최적구조 설계에 관한 연구 (A Study on Optimal Design Rule for Forward Extrusion Die)

  • 김창훈;김시영;김종호
    • 동력기계공학회지
    • /
    • 제3권1호
    • /
    • pp.45-49
    • /
    • 1999
  • Lots of products are made in various working conditions, depending on the size and the shape of them. Usually, at first, the die for new items had been designed on the basis of experience and know-how, and then modified through trial and error. At a die design stage most of drawings have been drawn manually. Recently some forging companies save design time by repeated utilization of standardized parts with registered data base. In this study the automated die design technique for forward extrusion of axisymmetric products is developed. A standardized die system is proposed from the investigation of ones employed frequently in the metal forming field and the design rules for cold extrusion die. A design example of forward extrusion die is given and discussed.

  • PDF

Pre-select Path Diversity with the Aid of Downlink Beamforming in Indoor MC-CDMA Systems

  • Pham, Van-Su;Le, Minh-Tuan;Linh Mai;Kim, Donghyun;Munhuyk Yim;Giwan Yoon
    • 한국정보통신학회:학술대회논문집
    • /
    • 한국해양정보통신학회 2004년도 SMICS 2004 International Symposium on Maritime and Communication Sciences
    • /
    • pp.20-23
    • /
    • 2004
  • In non-selective frequency environment, it is difficult to take the advantage of path diversity. In the literature, some methods have been proposed to solve the issue. This paper presents a new method to obtain the resolvable path in Indoor Multi-carrier Code Division Multiple Access (MC-CDMA) system by using downlink beam forming. With the aid of downlink beamforming, the most reliable path is found and chosen for the communication link. The new approach is evaluated in term of bit error rate (BER) and power consumption. The simulation results show that the new approach can get better BER performance. However, the cost of BER improvement is a small degradation in power reservation.

  • PDF

3D 스캐너를 이용한 커브드 모니터의 스프링백 분석 연구 (A study on the springback analysis of a curve monitor using a 3D scanner)

  • 윤형우;이춘규
    • Design & Manufacturing
    • /
    • 제12권3호
    • /
    • pp.13-18
    • /
    • 2018
  • Flexible display tends to grow every year, It tends to be larger, slimmer, and higher in image quality. Therefore, accuracy is required in the manufacturing process of each part. In the curved monitor, the bottom chassis has a structure to which other parts can be attached. The accuracy of the curvature which the bottom chassis of the curve monitor monitors has is important. If the curvature error is large, serious defects such as cracks, warpage, twisting and the like occur. Curvature was analyzed using 3D scanner. In the Forming process and Restriking process steps, spring go occurred, and spring back occurred in the Notching process and Bending process steps. Even in the same process, it was confirmed that the curvature value varied depending on the formed shape.

Augmentation of Hidden Markov Chain for Complex Sequential Data in Context

  • Sin, Bong-Kee
    • Journal of Multimedia Information System
    • /
    • 제8권1호
    • /
    • pp.31-34
    • /
    • 2021
  • The classical HMM is defined by a parameter triple �� = (��, A, B), where each parameter represents a collection of probability distributions: initial state, state transition and output distributions in order. This paper proposes a new stationary parameter e = (e1, e2, …, eN) where N is the number of states and et = P(|xt = i, y) for describing how an input pattern y ends in state xt = i at time t followed by nothing. It is often said that all is well that ends well. We argue here that all should end well. The paper sets the framework for the theory and presents an efficient inference and training algorithms based on dynamic programming and expectation-maximization. The proposed model is applicable to analyzing any sequential data with two or more finite segmental patterns are concatenated, each forming a context to its neighbors. Experiments on online Hangul handwriting characters have proven the effect of the proposed augmentation in terms of highly intuitive segmentation as well as recognition performance and 13.2% error rate reduction.

V-벤딩 금형에서 박판 소재의 실험과 해석을 통한 스프링 백 비교 고찰 (A comparative study of experiment and analysis of sheet matal in V-bending)

  • 정균민;최계광
    • Design & Manufacturing
    • /
    • 제15권1호
    • /
    • pp.21-25
    • /
    • 2021
  • When the product is removed from the mold after molding during the sheet metal molding process, elastic recovery causes a springback phenomenon. Much research has been done to minimize this phenomenon. In this study, V-bending experiments were conducted using galvanized steel sheets, stainless steel, and aluminum sheet materials, using a total of nine types of thin sheet materials of 1.0t, 1.5t, and 2.0t, respectively. Molding analysis and experimental data were compared and analyzed. In the case of galvanized steel sheets, it was considered that the springback phenomenon occurs more frequently in molding analysis than in experiments. It was considered that the springback phenomenon occurs greatly in the experiment, not the interpretation of the molding of the stainless steel plate and the aluminum plate. It was considered that the springback occurrence tendency of the molding analysis and the experiment was the same, and the springback occurrence error rate of the molding analysis and the experimental result was about 4.0%.

다중 회귀 분석을 활용한 Tee-Pipe 버링 공정에서 찢어짐 방지를 위한 피어싱 펀치 형상 최적 설계 (Multiple Regression Analysis for Piercing Punch Profile Optimization to Prevent Tearing During Tee Pipe Burring)

  • 이영섭;김준영;강정식;홍석무
    • 소성∙가공
    • /
    • 제26권5호
    • /
    • pp.271-276
    • /
    • 2017
  • A tee is the most common pipefitting used to combine or divide fluid flow. Tees can connect pipes of different diameters or change the direction of a pipe run. To manufacture tee type of stainless steel pipe, combinations of punch piercing and burr forming have been widely used in the industry. However, such method is considerably time consuming with regard to performing empirical work necessary to attain process conditions to prevent upper end tearing of the tee product and meet target tee height. Numerous experiments have shown that the piercing profile is the main cause of defects mentioned above. Furthermore, the mold design is formed through trial and error according to pipe diameters and changes in requirements. Thus, the objective of this study was to perform piercing and burring process analysis via finite element analysis using DYNAFORM to resolve problems mentioned above. An optimization design method was used to determine the piercing punch profile. Three radii of the piercing punch (i.e., large, small, and joined radii) were selected as design variables to minimize thinning of a tee pipe. Based on results of correlation and multiple regression analyses, we developed a predictive approximation model to satisfy requirements for both thickness reduction and target height. The new piercing punch profile was then applied to actual tee forming using the developed prediction equation. Model results were found to be in good agreement with experimental results.