• Title/Summary/Keyword: Second phase

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Effect of the change of second phase hardness on corrosion fatigue behavior of dual phase steel in 3% nacl solution (3% NaCl 수용액중에서 복합조직강의 부식피로거동에 미치는 제2상 속도변화의 영향)

  • 오세욱;김웅집
    • Journal of Ocean Engineering and Technology
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    • v.6 no.2
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    • pp.85-93
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    • 1992
  • The only hardness of 2nd phase of martensite in dual phase steel which was composed of the martensite and ferrite was changed. Fatigue test was conducted by cantilever type of self-made rotated bending fatigue testing machine. The corrosion fatigue fracture behaviors of dual phase steel were investigated in 3% NaCl solution at $N_f$ = $1.5\times$$10^5$ $N_f$=1.0 $\times$ $10^6$ cycles. The fatigue strength was increased with increasing the hardness of 2nd phase. The size and number of corrsion pits were influenced by the 2nd phase hardness and pits remain constant in size just after they were transited into cracks. The life of crack initiation was effected by stress level. The shape of relation of $\Delta$K and da/dn has smaller scattering in it in 3% NaCl solution than that in air. The higher the 2nd phase hardness is, the higher the corrosion fatigue life becomes. Corrosion fatigue fracture behavior was effected by mechanics in case of $N_f$=1.5$\times$10$^5$$N_f$=1.5$\times$10$^6$ cycles.

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A Study on the Application of PDCA Cycle for Performance Management of Promotion Project for Local Industry (향토산업육성사업의 성과관리를 위한 PDCA Cycle의 적용)

  • Son, Eun-Il;Hoshino, Satoshi;Song, Jung-Su
    • Journal of Korean Society of Rural Planning
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    • v.19 no.2
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    • pp.139-148
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    • 2013
  • This study verified for the necessity for the comprehensive analysis of outcomes resulting from the local industry promotion project in many respects. To analyze the operation planning for performance management of local industry promotion project, this study redesigns the so-called PDCA(Plan${\rightarrow}$Do${\rightarrow}$Check${\rightarrow}$Act) model which is also known as Deming Cycle and verifies some hypotheses. To accomplish study purposes, 169 response samples from 85 project groups which drive the local industry promotion project were verified using SPSS 12.0. The findings are as follows: First, there was a positive relationship between the planing phase and the implementation phase. Second, there was also a positive relationship between the implementation phase and completion of the project phase. Third, there was a positive relationship between the planing phase and completion of the project phase. Finally, the implementation phase was a partial mediator on the relationship between the planing phase and completion of the project phase. Based on these findings, the implications and the limitations of the research findings were discussed, and recommendations for future research were provided.

The Influence on the Corrosion Fatigue Crack Propagation in Changing of the Second Phase Hardness of Dual Phase Steel (複合組織鋼의 第2相 硬度變化가 腐蝕疲勞 크랙傳播에 미치는 影響)

  • 오세욱;김웅집
    • Journal of Welding and Joining
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    • v.11 no.2
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    • pp.42-52
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    • 1993
  • The corrosion fatigue fracture behaviour of dual phase steel was investigated in 3% NaCl solution at 302MPa and 137MPa. Fatigue test was conducted by cantilever type of self-made rotary bending fatigue testing machine. The fatigue strength increased with increasing the hardness of 2nd phase. Corrosion pit originated at the boundary of the 2nd phase. The size and number of corrosion pits were influenced by the 2nd phase hardness, and pits remained constant in size just after they were transited into cracks. The life of crack initiation was effected by stress level. The shape of relation of .DELTA. K and da/dN has smaller scattering in it in 3% NaCl solution than that in air. The higher the 2nd phase hardness is, the greater the corrosion fatigue life becomes. Corrosion fatigue fracture behaviour was primarily effected by mechanical factor in case of high stress(302MPa), but by electro-chemical reaction in a lower stress(137MPa). As stress level got lower and hardness of the 2nd phase got higher, the roughness of fracture surface increased.

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On the Undershoot Compensation in MIMO Systems with Nonminimum Phase Zeros

  • Lee, Sang-Yong;Kwon, Oh-Kyu
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.30-35
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    • 2003
  • In the control system analysis and synthesis, the nonminimum phase system has some difficulties due to the undershoot behaviour and the constrained sensitivity function. SISO problems has been widely investigated in the literatures, and it is well known that the undershoot cannot be eliminated by any linear feedback control. However, the undershoot compensation in MIMO system is less studied, and this paper is to deal with the zero property and the nonminimum phase behaviour of the MIMO system. Firstly, some definitions of the zeros will be introduced. Second, some systems including nonminimum phase transmission zeros are exemplified to show that the undershoot behaviour could be eliminated by a linear feedback in MIMO systems.

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A Study on Low Noise Frequency Synthesizer Design with Compact Size for Multi-Band (소형 다대역 저잡음 주파수 합성기 설계에 관한 연구)

  • Kim, Taeyoung;Han, Jonghoon
    • Journal of the Korea Institute of Military Science and Technology
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    • v.20 no.5
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    • pp.673-680
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    • 2017
  • In the proposed paper, we designed low noise frequency synthesizer with compact size for Multi-Band. The proposed frequency synthesizer consists of fundamental frequency band(2 GHz) and harmonic frequency band(4 GHz). To improve the phase noise and spurious level of frequency synthesizer, we analyze how the configuration of frequency synthesizer affect the phase noise and design the multi-band's structure. The implemented frequency synthesizer reduce both the phase noise and spurious level. The phase noise is -92.17 dBc/Hz at 1 kHz frequency offset in 2 GHz and -90.50 dBc/Hz at 1 kHz frequency offset in 4 GHz. All spurious signals including fundamental frequency are suppressed at least 20 dBc than the second harmonic frequency.

Effects of Microstructure on the Fatigue Crack Propagation Resistance in Dual Phase Steel (複合組織鋼 의 피勞균열進展抵抗 에 미치는 微視組織 의 영향)

  • 김정규;황돈영;박승락
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.8 no.1
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    • pp.34-40
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    • 1984
  • In this study, martensite-ferrite dual phase steel composed of martensite in hard phase and ferrite in soft phase is made as model material, and the difference of fatigue crack propagation behavior resulted from the structural size is investigated by fracture mechanics and microstructural method. The main results obtained are as follows; 1)Fatigue crack propagation rate is influenced by ferrite grain size. In other words, in the low .DELTA. K region fatigue crack propagation rate is decreased with decreasing of grain size but the difference of propagation rate resulted from the structural size is decreased as .DELTA.K is increased. 2)The above result is explained by the degree of crack arrest effect of second phase for fatigue crack propagation depending on the ratio of reversed plastic zone size to ferrite grain size.

An Investigation about Dynamic Behavior of Three Point Bending Specimen

  • Cho, Jae-Ung;Han, Moon-Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.4
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    • pp.149-157
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    • 2000
  • Computer simulations of the mechanical behavior of a three point bend specimen with a quarter notch under impact load are performed. The case with a load application point at the side is considered. An elastic-plastic von Mises material model is chosen. Three phases such as impact bouncing and bending phases are found to be identified during the period from the moment of impact to the estimated time for crack initiation. It is clearly shown that no plastic deformation near the crack tip is appeared at the impact phase. However it is confirmed that the plastic zone near the crack tip emerges in the second phase and the plastic hinge has been formed in the third phase. Gap opening displacement crack tip opening displacement and strain rate are compared with rate dependent material(visco-plastic material). The stability during various dynamic load can be seen by using the simulation of this study.

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Development of Correlation Based Feature Selection Method by Predicting the Markov Blanket for Gene Selection Analysis

  • Adi, Made;Yun, Zhen;Keong, Kwoh-Chee
    • Proceedings of the Korean Society for Bioinformatics Conference
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    • 2005.09a
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    • pp.183-187
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    • 2005
  • In this paper, we propose a heuristic method to select features using a Two-Phase Markov Blanket-based (TPMB) algorithm. The first phase, filtering phase, of TPMB algorithm works by filtering the obviously redundant features. A non-linear correlation method based on Information theory is used as a metric to measure the redundancy of a feature [1]. In second phase, approximating phase, the Markov Blanket (MB) of a system is estimated by employing the concept of cross entropy to identify the MB. We perform experiments on microarray data and report two popular dataset, AML-ALL [3] and colon tumor [4], in this paper. The experimental results show that the TPMB algorithm can significantly reduce the number of features while maintaining the accuracy of the classifiers.

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The Effects of the Microstructural Change of Dual Phase Steel on Fatigue Fracture Propagation (복합조직강의 미시조직변화가 피로파괴전파에 미치는 영향)

  • Oh, Sae-Wook;Kim, Ung-Jip
    • Journal of Ocean Engineering and Technology
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    • v.5 no.2
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    • pp.58-66
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    • 1991
  • Not only difference of fatigue crack growth and propagation behavior resulted from the grain size, the hardness ratio and volume fraction in M.E.F. dual phase steel composed of martensite in hard phase and ferrite in soft phase, but also the effects of the plastic constraint were investigated by fracture mechanics and microstructural method. The main results obtained are as follows: 1) The fatigue endurance of M.E.F. steel increases with decreasing the grain size, increasing the ratio of hardness and volume fraction. 2) The initiation of slip and crack occures faster as the stress level goes higher. These phenomena result from the plastic constraint effect of the second phase. 3) The crack propagation rate in the constant stress level is faster as the grain size gets larger, the ratio of hardness lower and volume fraction smaller.

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A Comparative Study of Two-phase Heuristic Approaches to General Job Shop Scheduling Problem

  • Sun, Ji Ung
    • Industrial Engineering and Management Systems
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    • v.7 no.2
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    • pp.84-92
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    • 2008
  • Scheduling is one of the most important issues in the planning and operation of production systems. This paper investigates a general job shop scheduling problem with reentrant work flows and sequence dependent setup times. The disjunctive graph representation is used to capture the interactions between machines in job shop. Based on this representation, four two-phase heuristic procedures are proposed to obtain near optimal solutions for this problem. The obtained solutions in the first phase are substantially improved by reversing the direction of some critical disjunctive arcs of the graph in the second phase. A comparative study is conducted to examine the performance of these proposed algorithms.