• Title/Summary/Keyword: Advanced techniques

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Characterization of Fiber Direction Influence in CFRP Composites Using Advanced NDE Techniques

  • Im, Kwang-Hee;Jang, Ju-Hwan;Back, Chong-Gui;Jeong, Ok-Su;Hsu, David K.
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.21 no.6
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    • pp.1003-1007
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    • 2012
  • A nondestructive technique would be very useful. Advanced NDE T-ray (terahertz ray) techniques of technology and instrumentation has provided a probing field on the electromagnetic spectrum. However, the T-ray is limited in order to penetrate a conducting material to some degree. Here, the T-ray would not go through easily the CFRP composite laminates since carbon fibers are electrically conducting while the epoxy matrix is not. So, investigation of terahertz time domain spectroscopy (THz TDS) was made and reflection and transmission configurations were studied for a 48-ply thermoplastic PPS(poly-phenylene sulfide)-based CFRP solid laminate. It is found that the electrical conductivity of CFRP composites depends on the direction of unidirectional fibers.

Simulation Study on the Performance Improvement of a Transcritical Carbon Dioxide Cycle (초월임계 이산화탄소 사이클의 성능향상에 관한 시뮬레이션 연구)

  • 조홍현;김용찬;서국정
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.2
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    • pp.158-166
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    • 2004
  • The performance of a heat pump using $CO_2$ is predicted and analyzed by using a cycle simulation model developed in this study. Cycle simulations are conducted by varying design parameters and operating conditions with the applications of advanced techniques to improve system performance. The applied systems in the simulations are internal heat exchanger, expander, and 2-stage compression with intercooling. As a result, the applications of advanced techniques improve the heating and cooling performances of the transcritical $CO_2$ cycle by 8∼26% and 20∼30%, respectively, over the basic cycle.

Development of Dynamic Frequency Monitoring Software for Wide-Area Protection Relaying Intelligence (광역 보호계전 지능화를 위한 동적 주파수 모니터링 S/W 개발)

  • Kim, Yoon-Sang;Park, Chul-Won
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.61 no.4
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    • pp.174-179
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    • 2012
  • The social and economic level of damages might be highly increased in the case of wide-area black-outages, because of heavy dependence of electricity. Therefore, the development of a wide-area protection relay intelligence techniques is required to prevent massive power outages and minimize the impact strength at failure. The frequency monitoring and prediction for wide-area protection relaying intelligence has been considered as an important technology. In this paper, a network-based frequency monitoring system developed for wide-area protection relay intelligence is presented. In addition, conventional techniques for frequency estimation are compared, and a method for advanced frequency estimation and measurement to improve the precision is proposed. Finally, an integrated monitoring system called K-FNET(Korea-Frequency Monitoring Network) is implemented based on the GPS and various energy monitoring cases are studied.

Micro-electrochemical Characteristics of Sensitized 304 Stainless steel Using Micro-droplet cell Techniques (마이크로 드로플릿 셀 기법을 이용한 예민화 된 304 스테인리스강의 미세전기화학 특성)

  • Kim, Kyu-Seop;Lee, Jae-Bong
    • Corrosion Science and Technology
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    • v.9 no.6
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    • pp.300-309
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    • 2010
  • The influences of sensitization on localized corrosion resistance of 304 stainless steel, were investigated, using micro-dropletcell techniques. Micro-droplet cell allows one to align the micro-electrode to the desired spot of the working electrode and measure directly local current with the potentiodynamic polarization, linear polarization and a.c. impedance. Micro-electrochemical tests were carried out inside of the grain and on grain boundaries separately. It was found that sensitization decreased the pitting potential, increasing corrosion current density around grain boundaries. Galvanic current density was also measured between grain and grain boundaries.

A case of maintenance activity in advanced countries for apparatus of electric rolling stock (전동차 전기장치의 선진 유지보수 활동사례)

  • Kim, Min-Pyo;Lee, Sang-Soo;Kwak, Sang-Log;Park, Chan-Woo;Cho, Yun-Ok
    • Proceedings of the KSR Conference
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    • 2006.11b
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    • pp.935-940
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    • 2006
  • Present periodic maintenance activities are carried on electric rolling stock in Korea based on predetermined inspection intervals. And this can be seen as a first generation of maintenance techniques without taking into consideration a degree of aging or degradation of the componets. In this study, we have analyzed the current status of maintenance being used in the techniques in various activities such as overseas railway operation organization, and good cases for the advanced country's maintenance system being carried out effectively. Based on the analysis, we would derive implications for efficient application and improvement guidance of maintenance system in electric rolling stock.

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Study for the Development of Fe-NbC Composites by Advanced PM Techniques

  • Gordo, E.;Gomez, B.;Gonzalez, R.;Ruiz-Navas, E.M.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.118-119
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    • 2006
  • The development of Fe-based metal matrix composites (MMCs) with high content of hard phase has been approached by combining the use of advanced powder metallurgy techniques like high-energy milling (HEM), cold isostatic pressing (CIP) and vacuum sinterings. A 30% vol. of NbC particles was mixed with Fe powder by HEM in a planetary mill during 10h, characteristing the powder by the observation of morphology and microstructure by scanning electron microscopy (SEM). After of sintering process the variation of density, hardness,carbon content and the microstructural changes observed, permits to find the optimal conditions of processing. Afterwards, a heat treatment study was performed to study the hardenability of the composite.

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Minimal sedation using oral sedatives for multi-visit dental treatment in an adult patient with dental phobia

  • Song, Seung-Rye;You, Tae Min
    • Journal of Dental Anesthesia and Pain Medicine
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    • v.21 no.4
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    • pp.369-376
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    • 2021
  • In adult patients with dental phobia, dental treatment may be difficult, or may not be possible. Depending on the level of fear or anxiety, non-pharmacological or pharmacological behavior management techniques are used in the dental treatment of such patients. Among the pharmacological behavior management techniques, minimal sedation, that is, the lowest depth of sedation, can be easily obtained in adult patients using oral sedatives, does not require special equipment or tools, and does not affect ventilatory and cardiovascular function. Diazepam is an anxiolytic drug belonging to the benzodiazepine family that, in addition to relieving anxiety, produces muscle relaxation, and is a representative drug used in adult patients with fear of dental treatment. Herein, we report the case of a 50-year-old woman with severe dental fear who successfully underwent long-term dental treatment in approximately 20 visits with minimal sedation using oral diazepam. In addition, we reviewed the considerations for the use of benzodiazepines for minimal sedation.

Implementation of a Recommendation system using the advanced deep reinforcement learning method (고급 심층 강화학습 기법을 이용한 추천 시스템 구현)

  • Sony Peng;Sophort Siet;Sadriddinov Ilkhomjon;DaeYoung, Kim;Doo-Soon Park
    • Proceedings of the Korea Information Processing Society Conference
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    • 2023.11a
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    • pp.406-409
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    • 2023
  • With the explosion of information, recommendation algorithms are becoming increasingly important in providing people with appropriate content, enhancing their online experience. In this paper, we propose a recommender system using advanced deep reinforcement learning(DRL) techniques. This method is more adaptive and integrative than traditional methods. We selected the MovieLens dataset and employed the precision metric to assess the effectiveness of our algorithm. The result of our implementation outperforms other baseline techniques, delivering better results for Top-N item recommendations.

Recent Progress of Hybrid Bonding and Packaging Technology for 3D Chip Integration (3D 칩 적층을 위한 하이브리드 본딩의 최근 기술 동향)

  • Chul Hwa Jung;Jae Pil Jung
    • Journal of the Semiconductor & Display Technology
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    • v.22 no.4
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    • pp.38-47
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    • 2023
  • Three dimensional (3D) packaging is a next-generation packaging technology that vertically stacks chips such as memory devices. The necessity of 3D packaging is driven by the increasing demand for smaller, high-performance electronic devices (HPC, AI, HBM). Also, it facilitates innovative applications across another fields. With growing demand for high-performance devices, companies of semiconductor fields are trying advanced packaging techniques, including 2.5D and 3D packaging, MR-MUF, and hybrid bonding. These techniques are essential for achieving higher chip integration, but challenges in mass production and fine-pitch bump connectivity persist. Advanced bonding technologies are important for advancing the semiconductor industry. In this review, it was described 3D packaging technologies for chip integration including mass reflow, thermal compression bonding, laser assisted bonding, hybrid bonding.

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Adaptive Fuzzy Inference System using Pruning Techniques

  • Kim, Chang-Hyun;Jang, Byoung-Gi;Lee, Ju-Jang
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 2003.09a
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    • pp.415-418
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    • 2003
  • Fuzzy modelling has the approximation property far the given input-output relationship. Especially, Takagi-Sugeno fuzzy models are widely used because they show very good performance in the nonlinear function approximation problem. But generally there is not the systematic method incorporating the human expert's knowledge or experience in fuzzy rules and it is not easy to End the membership function of fuzzy rule to minimize the output error as well. The ANFIS (Adaptive Network-based Fuzzy Inference Systems) is one of the neural network based fuzzy modelling methods that can be used with various type of fuzzy rules. But in this model, it is the problem to End the optimum number of fuzzy rules in fuzzy model. In this paper, a new fuzzy modelling method based on the ANFIS and pruning techniques with the measure named impact factor is proposed and the performance of proposed method is evaluated with several simulation results.

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