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The Effect of Loading Waveform on the High Temperature Fatigue Crack Propagation in P92 and STS 316L Steel (P92와 STS 316L강의 고온 피로 균열 성장에 미치는 하중 파형의 영향)

  • 김수영;임병수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.4
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    • pp.136-140
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    • 2002
  • High temperature fatigue crack growth behavior of P92 and STS 316L steel were investigated under four load conditions using CT type specimens. Loading and unloading times for the low wave forms were combinations of 1 sec. and 50 sec., which were two symmetric wave forms and two unsymmetric wave forms. Their behaviors are characterized using ΔK parameter. In STS 316L, Crack growth rate generally increases as frequency decreases. However, sensitivity of the loading rate to crack growth rate was fecund to be far greater than that of the unloading time. It is because as loading time increases, creep occurs at crack tip causing the crack growth rate to increase. However creep does not occur at the crack tip even if the unloading time is increased. In P92 steel, crack growth rate showed same behavior as in STS 316L. But the increase in loading or unloading time made almost no difference in crack growth rate, suggesting that no significant creep occurs in P92 steel even though loading time increases. After conducting high temperature tensile tests and comparing high temperature fatigue crack growth rates under various wave forms, it was proved that P92 steel has not only good high temperature properties but also improved, better high temperature fatigue properties than STS 316L.

Selecting the Optimal Loading Location through Prediction of Required Amount for Goods based on Bi-LSTM (Bi-LSTM 기반 물품 소요량 예측을 통한 최적의 적재 위치 선정)

  • Sein Jang;Yeojin Kim;Geuntae Kim;Jonghwan Lee
    • Journal of the Semiconductor & Display Technology
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    • v.22 no.3
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    • pp.41-45
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    • 2023
  • Currently, the method of loading items in the warehouse, the worker directly decides the loading location, and the most used method is to load the product at the location closest to the entrance. This can be effective when there is no difference in the required amount for goods, but when there is a difference in the required amount for goods, it is inefficient because items with a small required amount are loaded near the entrance and occupy the corresponding space for a long time. Therefore, in order to minimize the release time of goods, it is essential to select an appropriate location when loading goods. In this study, a method for determining the loading location by predicting the required amount of goods was studied to select the optimal loading location. Deep learning based bidirectional long-term memory networks (Bi-LSTM) was used to predict the required amount for goods. This study compares and analyzes the release time of goods in the conventional method of loading close to the entrance and in the loading method using the required amount for goods using the Bi-LSTM model.

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Acceleration Techniques of Application Startup for Embedded Systems (임베디드 환경에서 응용프로그램 시작의 가속 기법)

  • Park, Eun-Byung;Lee, Yong-Jun;Kim, Seungkyun;Lee, Jaejin;Park, Kyungmin
    • IEMEK Journal of Embedded Systems and Applications
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    • v.4 no.4
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    • pp.174-179
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    • 2009
  • Due to digital convergence, mobile embedded systems need more functionalities and a fully fledged OS. Applications for such embedded systems are linked with many shared libraries available in the OS and access a large data set at launch time. This results in increased application launch time. In this paper, we propose two techniques for reducing the application launch time: lazy-loading and pinning. Lazy-loading defers loading shared libraries that are not used in the application at launch time, whereas pinning guarantees the residence of shared libraries and data used at launch time in the main memory.

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STABILITY CHANGES OF IMMEDIATELY LOADED AND DELAYED LOADED IMPLANTS IN EDENTULOUS MANDIBLE (하악 무치악에서 즉시하중과 지연하중간 임플랜트의 안정성 변화)

  • Jung, Hye-Eun;Kim, Dae-Gon;Park, Chan-Jin;Cho, Lee-Ra;Yi, Yang-Jin
    • The Journal of Korean Academy of Prosthodontics
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    • v.45 no.2
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    • pp.250-262
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    • 2007
  • Statement of problem: It was reported high success rate of implant-supported fixed prostheses using with $5{\sim}6$ implants on anterior mandible. Recently, immediate loading protocol was focused to overcome disadvantages of classic 2-stage delayed loading protocol. Purpose: This clinical study was to evaluate stability changes with time of immediately loaded and delayed loaded implants in edentulous mandible and to compare stability changes with time according to implantation sites. Materials and methods: Five or six implants were placed on anterior mandible depending on the arch shape. The immediately loading group was consisted of 8 patients received their prostheses within $24{\sim}48$ hours after implantation. The delayed loading group was consisted of 8 patients received their definitive prostheses following classical prosthetic procedures after a healing period of 3 months. All patients were recalled every 6 months for check-up. The evaluations of radiographic examination, ISQ value measurement and recording of complication were done. To evaluate marginal bone level, intraoral periapical radiographs were taken with long cone paralleling technique. At every evaluation recall, all prostheses were removed and ISQ values were measured with OsstellTM on individual implants. Results: 1. None of implants was failed. All implants showed stable marginal bone levels and ISQ values. 2. Marginal bone level changes with time showed statistically significant difference between immediately loading group and delayed loading group (P<0.001). 3. ISQ value changes with time did not show statistically significant difference between immediately loading group and delayed loading group (P=0.079). ISQ value decreased with time in both groups, however, all implants showed stable ISQ value at 30 months-recall evaluation. 4. Marginal bone level changes with time did not show statistically significant differences among implantation sites (P=0.604). 5. ISQ value changes with time showed statistically significant differences among implantation sites (P=0.047). ISQ values of most posterior implants decreased with time comparing to other implants. Conclusion: Although the marginal bone level of the terminal abutment didn't different with the other implants, ISQ value of the terminal abutment was lower than that of the other implants. Therefore, further clinical evaluation would be needed in this point of view.

자동선반을 위한 공작물 장탈착로봇의 개발

  • 고경철;김용일;권영두;정종기
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1992.04a
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    • pp.364-368
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    • 1992
  • The conventional loading process of workpieces for a CNC lathe is performaed either by human or by a general robot. It is not suitable for a general robot to load workpieces because of high price and inefficiency. Starting from the description of the environment around CNC lathes and the analysis ofloading process, we have developed the task-oriented loading manipulator. The characteristics of a loading manipulator are the following: to load/unload heavy workpieces, to decrease the whole porcess time. The air-chuck to load heavy workpiece has high clamping force and light weight. A loading manipulator has accomplished both the integration of independent automation techniques and cost-down effect of product. A loading manupulator developed in this project has been designed for general loading process. The loading manipulator is capable of carrying heavy payload with respect to weight of robot in short cycle time.

The Effect of Sample Handling on the Rheological Measurement of Regenerated Silk Fibroin Formic Acid Solution using Parallel Plate Geometry

  • Cho, Hee-Jung;Um, In-Chul
    • International Journal of Industrial Entomology and Biomaterials
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    • v.22 no.1
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    • pp.5-10
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    • 2011
  • The effect of sample handling condition on the rheological measurement of regenerated silk fibroin formic acid solution using parallel plate geometry was investigated. In case of loading method, the loading by pouring sample solution resulted in the best reproducibility of rheological measurement. Loading with spoon showed a high variance of viscosity value at low shear rate region ($0.01{\sim}1sec^{-1}$) while loading with syringe exhibited a low reproducibility of viscosity at high shear region ($1{\sim}100sec^{-1}$) with a disappearance of shear thinning phenomenon. It was revealed that the sample loading with small extra amount lead to the most reproducible result. The sample loading with the exact amount for the measuring plate resulted in a lack of reproducibility of high shear viscosity, while the loading with large extra volume produced a limited consistency of low shear viscosity. It was turned out that 3 min. of waiting time before measurement was the optimum condition for reliable result. When the waiting time was less than 1 min., the low shear viscosity was obtained with a lack of consistency. On the other hand, the sample solution started drying when the waiting time increased up to 5 min.

Machine Loading by Workload Balancing in Flexible Manufacturing Systems (FMS에서의 작업부하균형을 고려한 기계부하결정)

  • Yun, Yeong-Su;Lee, Sang-Yong
    • Journal of Korean Society for Quality Management
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    • v.20 no.2
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    • pp.129-136
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    • 1992
  • This paper aims to develope an algorithm to minimize the total production time, sum of group formation times and processing times, under the balanced workload among the machines by grouping parts with machine loading in FMS. The algorithm of this study is composed of four step procedures ; (1) Parts grouping by Group Technology(GT) (2) Minimizing total processing time in loading problem (3) Machine workload balancing, including above(2) (4) Group formation time, including above(3) For parts grouping, Rank Order Clustering(ROC) algorithm developed by King(1980) is used and this algorithm is programmed by using the MACRO functions of QUATTRO Pro, one of the spreadsheet packages. The structure for loading model is solved by using the Hyper-LINDO. As a case study, numerical examples are demonstrated to show the effectiveness of the proposed machine loading procedure.

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A Real-Time Loading Strategy of Batch Processing Machines for Average Tardiness Minimization (평균납기지연 최소화를 위한 배치생산공정의 실시간 로딩전략)

  • Koo, Pyung-Hoi
    • Journal of Korean Institute of Industrial Engineers
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    • v.40 no.2
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    • pp.215-222
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    • 2014
  • This paper provides a real-time loading strategy for batch processing machines in which a number of jobs are simultaneously processed as a batch. The batch processing machines can be seen in both manufacturing industries (e.g., semiconductor, automobile and metal working) and service industries (transportation vehicles, mail shipment and theme park). This paper focuses on batch processing machines in semiconductor manufacturing. We present a look-ahead loading strategy for tardiness minimization where future arrivals and due dates are taken into consideration. Simulation tests are performed on the presented strategy and some existing loading heuristics under various production settings with different traffic intensities and forecasting errors. Experimental results show that our strategy provides the performance of good quality.

Effective Optimization by Comparison with Game Loading Time for File Format of Textures - Based on Virtools Engine - (텍스처의 파일 저장형식에 따른 게임 로딩 시간 비교를 통한 효과적인 최적화 기법에 관한 연구 - Virtools 엔진을 기반으로 -)

  • Chae, Heon-Joo;Ryu, Seuc-Ho
    • The Journal of the Korea Contents Association
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    • v.7 no.5
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    • pp.72-77
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    • 2007
  • A game starting, the process of running has some loading steps. In general, textures use corresponding images saved externally and the file format of images affects the loading time of game. We propose some ideas for the texture using method by comparison with loading time according to some file formats.

Modeling of time-varying stress in concrete under axial loading and sulfate attack

  • Yin, Guang-Ji;Zuo, Xiao-Bao;Tang, Yu-Juan;Ayinde, Olawale;Ding, Dong-Nan
    • Computers and Concrete
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    • v.19 no.2
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    • pp.143-152
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    • 2017
  • This paper has numerically investigated the changes of loading-induced stress in concrete with the corrosion time in the sulfate-containing environment. Firstly, based on Fick's law and reaction kinetics, a diffusion-reaction equation of sulfate ion in concrete is proposed, and it is numerically solved to obtain the spatial and temporal distribution of sulfate ion concentration in concrete by the finite difference method. Secondly, by fitting the existed experimental data of concrete in sodium sulfate solutions, the chemical damage of concrete associated with sulfate ion concentration and corrosion time is quantitatively presented. Thirdly, depending on the plastic-damage mechanics, while considering the influence of sulfate attack on concrete properties, a simplified chemo-mechanical damage model, with stress-based plasticity and strain-driven damage, for concrete under axial loading and sulfate attack is determined by introducing the chemical damage degree. Finally, an axially compressed concrete prism immersed into the sodium sulfate solution is regarded as an object to investigate the time-varying stress in concrete subjected to the couplings of axial loading and sulfate attack.