• Title/Summary/Keyword: FEAS

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Investigation into the Effects of Process Parameters of DED Process on Deposition and Residual Stress Characteristics for Remanufacturing of Mechanical Parts (기계 부품 재제조를 위한 DED 공정 조건에 따른 적층 및 잔류응력 특성 분석)

  • Kim, D.A.;Lee, K.K.;Ahn, D.G.
    • Transactions of Materials Processing
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    • v.30 no.3
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    • pp.109-118
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    • 2021
  • Recently, there has been an increased interest in the remanufacturing of mechanical parts using metal additive manufacturing processes in regards to resource recycling and carbon neutrality. DED (directed energy deposition) process can create desired metallic shapes on both even and uneven substrate via line-by-line deposition. Hence, DED process is very useful for the repair, retrofit and remanufacturing of mechanical parts with irregular damages. The objective of the current paper is to investigate the effects DED process parameters, including the effects of power and the scan speed of the laser, on deposition and residual stress characteristics for remanufacturing of mechanical parts using experiments and finite element analyses (FEAs). AISI 1045 is used as the substrate material and the feeding powder. The characteristic dimensions of the bead shape and the heat affected zone (HAZ) for different deposition conditions are obtained from the experimental results. Efficiencies of the heat flux model for different deposition conditions are estimated by the comparison of the results of FEAs with those of experiments in terms of the width and the depth of HAZ. In addition, the influence of the process parameters on residual stress distributions in the vicinity of the deposited region is investigated using the results of FEAs. Finally, a suitable deposition condition is predicted in regards to the bead formation and the residual stress.

Fabrication of Sputtered Gated Silicon Field Emitter Arrays with Low Gate Leakage Currents by Using Si Dry Etch

  • Cho, Eou Sik;Kwon, Sang Jik
    • Transactions on Electrical and Electronic Materials
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    • v.14 no.1
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    • pp.28-31
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    • 2013
  • A volcano shaped gated Si-FEA (silicon field emitter array) was simply fabricated using sputtering as a gate electrode deposition and lift-off for the removal of the oxide mask, respectively. Due to the limited step coverage of well-controlled sputtering and the high aspect ratio in Si dry etch caused by high RF power, it was possible to obtain Si FEAs with a stable volcano shaped gate structure and to realize the restriction of gate leakage current in field emission characteristics. For 100 tip arrays and 625 tip arrays, gate leakage currents were restricted to less than 1% of the anode current in spite of the volcano-shaped gate structure. It was also possible to keep the emitters stable without any failure between the Si cathode and gate electrode in field emission for a long time.

FEAS, Interactive Communication Tool to Understand Performance Assessment Approaches on Permanent HLW Disposal (인터액티브한 FEAS 프로그램을 이용한 고준위 방사성 폐기물 처분장 안전성 평가 방안)

  • 황용수;서영웅;김성기;강철형
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 2001.11a
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    • pp.331-336
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    • 2001
  • 한국원자력연구소에서는 고준위 방사성폐기물 처분 시스템의 안전성을 투명하게평가하기 위한 방안의 하나로 처분 안전성 관련 시나리오와 구성 요소들인 FEP, 그리고 각 시나리오 별 안전성 평가 방안들을 종합한 프로그램인 FEAS를 개발하고 있다. 고준위 방사성 폐기물 처분 연구는 관련 전문가 뿐 아니라 일반 국민들도 안전성에 관해 많은 관심을 표명하고 있는 바 현재 국내에서 고려하고 있는 처분 개념은 무엇이며 처분장 안전성 평가를 위해서 고려하고 있는 제 사건들은 무엇이며 이들 시나리오를 구성하는 세부 사건들은 무엇인가에 관한 합의를 도출하고 이와 관련된 기록들을 보존하고 각각 세부 사건들에 관해 현재의 평가 방안과 데이터 수집 현황 그리고 해외 사례 등을 체계적으로 정리하는 일은 중요하다. 현재 개발되고 있는 FEAS는 이와 같은 역할을 수행할 뿐 아니라 이 프로그램과 동시에 개발되고 있는 입력 자료 데이터 시스템, 웹을 기반으로 한 품질 보증 체제 및 안전성 평가 방안 등과 향후 연계되어 모든 국민들이 방사성 폐기물 처분장의 안전성을 쉽게 이해할 수 있는 수단으로 확장될 예정이다.

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Fabrication and Characteristics of CNT-FEAs with Under-gate Structure

  • Noh, Hyung-Wook;Jun, Pil-Goo;Ko, Sung-Woo;Kwak, Byung-Hwak;Park, Sang-Sik;Lee, Jong-Duk;Uh, Hyung-Soo
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07b
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    • pp.1470-1473
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    • 2005
  • We proposed new triode-type Field Emitter Arays using Carbon NanoTubes(CNT-FEAs) as electron emission sources at low electric fields. The CNTs were selectively grown on the patterned catalyst layer by Plasma-Enhanced Chemical Vapor Deposition (PECVD). In this structure, gate electrodes are located underneath the cathode electrodes and extracted gate is surrounded by CNT emitters. Furthermore, in order to control density of CNTs, we investigated effect of using rapid thermal annealing (RTA).

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Enhanced characteristics of Molybdenum field emission arrays under laser irradiation

  • 송병권;서도석;남창우;홍진표;김채옥;차승남;이항우;박남신;이내성
    • Proceedings of the Korean Vacuum Society Conference
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    • 2000.02a
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    • pp.154-154
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    • 2000
  • FED(Field emission display)의 FEAs(Field emitter arrays)에 형성되어 있는 micro-tip 은 tip 표면의 오염이나 진공내부의 잔류가스에 대단히 민감하다. 특히, emitter 물질의 일함수 및 겉모양 같은 기하학적 요소에 민감한 전계방출 소자의 특성상 tip 선단이 oxidation 될 경우 일함수가 증가하여 전자방출에 필요한 구동전압이 증가하고 전자 방출의 불균일성이 커지는 문제점이 발생한다. 이에 고진공의 동작 환경 및 FEAs 제작과정이나 공기의 노출에 발생하는 tip 표면의 오염물질 제거가 요구된다. 따라서 본 연구에서는 40$\times$40mm2 FEAs에 laser power, scan speed을 달리하며 laser(cw Nd-YAG, 1064nm)을 조사하였다. laser cleaning 효과를 보기 위해 laser irradiation 전, 후에 진공도 5$\times$10-7torr irradiation 후에 emitter tip의 뚜렷한 기하학적 모양의 변화를 볼 수는 없었지만, I-V 특성이 향상 되는 것을 볼 수 있었다.

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A Study on the Design of Bending Dies for Forming of DP590 High Strength Steel Sheet (DP590 고장력 강판 성형을 위한 굽힘 금형 설계에 관한 연구)

  • J. P. Cheon;D. G. Ahn
    • Transactions of Materials Processing
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    • v.33 no.1
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    • pp.43-49
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    • 2024
  • A high strength steel sheet (HSSS) has widely used to improve the specific rigidity of parts and the safety of the passenger in automotive industries. However, the HSSS is difficult to manufacture precise parts through a forming process due to the reduced elongation and the increased elastic recovery. The goal of the paper is to investigate the improved design of bending dies for DP590 HSSS. The over forming type bending dies with cam systems added to the side of the formed part is proposed to improve the quality of the part. The effects of the die design and the forming parameter on formability and elastic recovery characteristics is examined using finite element analyses (FEAs). From the results of FEAs, proper die design and forming parameters are predicted.

Fabrication of silicon field emitter array using chemical-mechanical-polishing process (기계-화학적 연마 공정을 이용한 실리콘 전계방출 어레이의 제작)

  • 이진호;송윤호;강승열;이상윤;조경의
    • Journal of the Korean Vacuum Society
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    • v.7 no.2
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    • pp.88-93
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    • 1998
  • The fabrication process and emission characteristics of gated silicon field emitter arrays(FEAs) using chemical-mechanical-polishing (CMP) method are described. Novel fabrication techniques consisting of two-step dry etching with oxidation of silicon and CMP processes were developed for the formation of sharp tips and clear-cut edged gate electrodes, respectively. The gate height and aperture could be easily controlled by varying the polishing time and pressure in the CMP process. We obtained silicon FEAs having self-aligned and clear-cut edged gate electrode opening by eliminating the dishing problem during the CMP process with an oxide mask layer. The tip height of the finally fabricated FEAs was about 1.1 $\mu$m and the end radius of the tips was smaller than 100 $\AA$. The emission current meaured from the fabricated 2809 tips array was about 31 $\mu$A at a gate voltage of 80 V.

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A Systematic Review of Randomized Controlled Trials on Acupuncture Treatment for Low Back Pain Based on FEAS (요통에 대한 침치료 무작위대조군임상연구(RCT)의 FEAS 분석을 통한 계통적 분석 연구)

  • Nam, Dong-Woo;Kang, Jung-Won;Kim, Eun-Jung;Kim, Hyun-Wook;Song, Ho-Sueb;Kim, Sun-Woong;Kim, Kap-Sung;Lee, Geon-Mok;Choi, Dong-Young;Lee, Jae-Dong
    • Journal of Acupuncture Research
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    • v.26 no.3
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    • pp.133-147
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    • 2009
  • Objectives : To review RCTs on acupuncture treatment for low back pain in order to establish a standard acupuncture treatment model in treating low back pain. Methods : RCT articles on traditional acupuncture treatment for low back pain were searched through online database. Study Quality was assessed using the FEAS. Results : Ten out of the one hundred six articles searched were reviewed. Among the ten articles reviewed, six articles compared acupuncture treatment with no treatment or non-penetrating sham acupuncture. All six articles concluded significantly positive effect of acupuncture compared to the control. Conclusions : The ideal acupuncture treatment model for low back pain was obtained as follows. A sterile disposable stainless steel(0.30mm${\times}$40mm) should be inserted to more than six acupuncture points on the BL, GV and GB meridians such as $BL_23$, $BL_25$, $BL_40$, $BL_60$, $GV_4$ and $GB_30$. Sparrow pecking method to obtain 'de-qi' is recommended and repeated stimulation during the 20 minute retention time is necessary. Ideal treatment frequency would be more than one a week for about 7 weeks.

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A Systematic Review of Randomized Controlled Trials on Acupuncture Treatment for Neck Pain (경항통에 침치료를 시행한 무작위대조군연구(RCT)들에 대한 계통적 연구)

  • Kim, Hyun-Wook;Kim, Sung-Soo;Kang, Jung-Ah;Nam, Dong-Woo;Kim, Eun-Jung;Hong, Kwon-Eui;Kim, Sung-Chul;Lee, Jae-Dong;Kim, Kap-Sung;Lee, Geon-Mok
    • Journal of Acupuncture Research
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    • v.26 no.2
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    • pp.103-123
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    • 2009
  • Objectives : The aim of this study is to review RCTs of acupuncture treatment for neck pain and to establish standards of acupuncture treatment for neck pain. Methods : We searched articles in Pubmed using ICD 10. Study quality was assessed using the FEAS and Jadad score. Results and Conclusions : Three review studies and nineteen clinical trials were searched and reviewed. Among the nineteen clinical trials reviewed, positive outcome was reported in thirteen studies. Most frequently used meridians were GB, BL, SI, GV and LI, The most frequently used acupuncture points were $GB_{20}$, $GB_{21}$, $LI_4$, $BL_{10}$, $GV_{14}$ and $SI_3$. More than two needles were inserted in the studies and needle retention time was more than 10 minutes. The most frequently used needle length was 40mm, and diameter was 0.25mm and 0.30mm. The mean number of treatment sessions were more than 10 times. Frequency of treatment was more than once a week, And treatment duration was more! than 5 weeks. The total FEAS scores ranged from 3 to 15.5, and the mean value was 9.39. Jadad score ranged from 2 to 5, and the mean value was 3.42. The number of studies scoring over three points on the Jadad scale was sixteen.

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Building Transparency on the Total System Performance Assessment of Radioactive Repository through the Development of the Cyber R&D Platform; Application for Development of Scenario and Input of TSPA Data through QA Procedures (Cyber R&D Platform개발을 통한 방사성폐기물 처분종합성능평가(TSPA) 투명성 증진에 관한 연구; 시나리오 도출 과정과 TSPA 데이터 입력에서의 품질보증 적용 사례)

  • Seo, Eun-Jin;Hwang, Yong-Soo;Kang, Chul-Hyung
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.4 no.1
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    • pp.65-75
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    • 2006
  • Transparency on the Total System Performance Assessment (TSPA) is the key issue to enhance the public acceptance for a radioactive repository. To approve it, all performances on TSPA through Quality Assurance is necessary. The integrated Cyber R&D Platform is developed by KAERI using the T2R3 principles applicable for five major steps : planning, research work, documentation, and internal & external audits in R&D's. The proposed system is implemented in the web-based system so that all participants in TSPA are able to access the system. It is composed of three sub-systems; FEAS (FEp to Assessment through Scenario development) showing systematic approach from the FEPs to Assessment methods flow chart, PAID (Performance Assessment Input Databases) being designed to easily search and review field data for TSPA and QA system containing the administrative system for QA on five key steps in R&D's in addition to approval and disapproval processes, corrective actions, and permanent record keeping. All information being recorded in QA system through T2R3 principles is integrated into Cyber R&D Platform so that every data in the system can be checked whenever necessary. Throughout the next phase R&D, Cyber R&D Platform will be connected with the assessment tool for TSPA so that it will be expected to search the whole information in one unified system.

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