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SHS 공정에 의해 제조된 Mo<sub>x</sub>W<sub>1-x</sub>Si<sub>2</sub> 발열체의 열화메커니즘
이동원,이상헌,김용남,이성철,구상모,오종민,Lee, Dong-Won,Lee, Sang-Hun,Kim, Yong-Nam,Lee, Sung-Chul,Koo, Sang-Mo,Oh, Jong-Min 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.10
The degradation mechanism of $Mo_xW_{1-x}Si_2$ ultrahigh-temperature heating elements fabricated by self-propagating high-temperature synthesiswas investigated. The $Mo_xW_{1-x}Si_2$ specimens (with and without post-annealing) were subjected to ADTs (accelerated degradation tests) at temperatures up to $1,700^{\circ}C$ at heating rates of 3, 4, 5, 7, and $14^{\circ}C/min$. The surface loads of all the specimen heaters were increased with the increase in the target temperature. For the $Mo_xW_{1-x}Si_2$ specimens without annealing, many pores and secondary-phase particles were observed in the microstructure; the surface load increased to $23.9W/cm^2$ at $1,700^{\circ}C$, while the bending strength drastically reduced to 242 MPa. In contrast, the $Mo_xW_{1-x}Si_2$ specimens after post-annealing retained $single-Mo_xW_{1-x}Si_2$ phases and showed superior durability after the ADT. Consequently, it is thought that the formation of microcracks and coarse secondary phases during the ADT are the main causes for the degraded performance of the $Mo_xW_{1-x}Si_2$ heating elements without post-annealing.
SHS 공정으로 제조된 Mo<SUB>x</SUB>W<SUB>1-x</SUB>Si₂ 발열체의 가속수명시험과 고장분석
이동원(Dong-Won Lee),이상헌(Sang-Hun Lee),김용남(Yong-Nam Kim),이희수(Heesoo Lee),이성철(Sung-Chul Lee),구상모(Sang-Mo Koo),오종민(Jong-Min Oh) 한국전기전자학회 2017 전기전자학회논문지 Vol.21 No.3
고온자전합성과 후열처리 공정으로 MoxW1-xSi₂ 발열체를 제조하였다. MoxW1-xSi₂ 발열체의 신뢰성을 검증하기 위해 가속수명시험을 수행하였으며, 수명시간을 Minitab 프로그램으로 추정하였다. 또한, 가속수명시험 후의 MoxW1-xSi₂ 발열체의 고장분석을 전기적과 구조적 특성으로부터 수행하였다. 그 결과, MoxW1-xSi₂ 발열체의 지배적인 고장 유형은 발열체 내부의 크랙 형성과 SiO₂ 보호층의 박리임을 확인하였다. MoxW1-xSi₂ heaters were fabricated by self-propagating high-temperature synthesis (SHS) process and post sintering process. To validate the reliability of the MoxW1-xSi₂ heaters, the accelerated life test (ALT) was conducted, and then lifetime to MoxW1-xSi₂ heaters was estimated by using Minitab programs. Also, the failure analysis of MoxW1-xSi₂ heaters after ALT was performed through electrical and structural properties. As the results, it was confirmed that the dominant failure mode of MoxW1-xSi₂ heaters is the crack formation in heaters and the delamination of protective SiO₂ layers.
산업현장 추락에 대한 기계학습 알고리즘 기반의 다집단 분류
구범모(Bum Mo Koo),김종만(Jong Man Kim),남예진(Ye Jin Nam),성동진(Dong Jin Sung),심재우(Jae Woo Shim),양수민(Su Min Yang),김영호(Young Ho Kim) 대한기계학회 2022 大韓機械學會論文集A Vol.46 No.3
본 연구에서는 웨어러블 관성센서를 사용하여 산업현장 추락에 대한 기계학습 기반의 다집단 분류를 시도하였다. 20명의 건강한 성인 남성을 모집하였으며, 15가지 non-FFH 동작과 5가지 low-hazard-FFH 동작 그리고 한 가지 high-hazard-FFH 동작을 3회씩 반복 측정하였다. 5개의 기계학습 기법(SVM, k-NN, LDA, QDA, MLP)에 대하여 two-class 분류성능과 three-class 분류성능을 비교하였다. 분석 결과 SVM이 two-class 분류와 three-class 분류에서 각각 99.5%와 98.2%의 가장 높은 정확도를 보였다. 또한, 세 가지 전처리 기법들(SMOTE, min-max 정규화, univariant feature selection) 역시 알고리즘 성능 향상에 기여함을 볼 수 있었다. In this study, a multi-class classification of industrial fall from height (FFH) based on machine learning was tried using a wearable inertial sensor. Twenty healthy adult males were recruited for the experiment. The experiment protocol consisted of 15 non-FFH, five low-hazard-FFH, and one high-hazard-FFH. Each motion was conducted three times repeatedly. Two-class classification performance and three-class classification performance were compared for five different machine learning techniques (SVM, k-NN, LDA, QDA, and MLP). As a result, SVM showed the highest accuracy of 99.52% and 98.25% in two-class classification and three-class classification, respectively. In addition, the three preprocessing techniques (SMOTE, min-max regularization, and univariant feature selection) contributed to the improvement of algorithm performance.
Cho, Myung-Yeon,Lee, Sung-Chul,Park, Chulhwan,Lee, Daeseok,Koo, Sang-Mo,Moon, Kyoung-Sook,Lee, Dong-Won,Oh, Jong-Min Elsevier 2019 INTERMETALLICS Vol.110 No.-
<P><B>Abstract</B></P> <P>High-performance tungsten molybdenum disilicide (Mo<SUB>x</SUB>W<SUB>1-x</SUB>Si<SUB>2</SUB>) heating elements were prepared using a self-propagating high temperature synthesis process. The effect of post annealing on the degradation behavior of the alloy was experimentally investigated. Increasing the attrition milling time up to 20 min during powder preparation resulted in Mo<SUB>x</SUB>W<SUB>1-x</SUB>Si<SUB>2</SUB> heaters with the highest density, which increased the fracture strength compared to samples with shorter attrition times. Such samples were annealed and evaluated as heating elements using accelerated degradation tests and failure analysis in order to compare their structural characteristics and flexural strength with as-fabricated samples. The annealed Mo<SUB>x</SUB>W<SUB>1-x</SUB>Si<SUB>2</SUB> heater showed a relatively dense structure with few pores and no secondary phases, apart from a SiO<SUB>2</SUB> layer. This favorable structure prevented bubble formation, which can result in fracturing of the heater, as revealed by evaluation at high temperatures with various heating rates. The flexural strength of the annealed specimen was 2.5-times higher than that of the as-fabricated specimen, which was attributed to removal of secondary phases during annealing. Failure time and surface load analyses were used to investigate the fracture mechanism of the Mo<SUB>x</SUB>W<SUB>1-x</SUB>Si<SUB>2</SUB> heaters in detail at 1790 °C by quantifying bubble formation and the presence of secondary phases.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Self-propagating high temperature synthesis of Mo<SUB>x</SUB>W<SUB>1-x</SUB>Si<SUB>2</SUB> heaters demonstrated. </LI> <LI> Post-annealed Mo<SUB>x</SUB>W<SUB>1-x</SUB>Si<SUB>2</SUB> heaters were highly dense, with good flexural strength. </LI> <LI> Bubble formation (the main cause of fracture) suppressed at ultra-high temperature (above 1700 °C). </LI> <LI> Surface load, failure time, and bubble formation used to study fracture mechanisms. </LI> </UL> </P>
박찬구,윤중섭,김민영,손종열,모세영 한국대기환경학회 2004 한국대기환경학회지 Vol.20 No.3
The results of individual PAH source profiles that can be applied to receptor model are as follows. The sum of 16 PAH concentrations was 391.41 ng/S㎥ in a tunnel. Phenanthrene was the most abundant compound among 16 PAH, and then pyrene, fIuoranthene, anthracene, and naphthalene can be seen in elevated contents. 11,056.61 ng/S㎥ of 16 PAH concentrations in BC oil boiler was two times higher than 6,582.57 ng/S㎥ of those in LNG boiler. Naphthalene was the most abundant compound in both facilities. Phenanthrene, anthracene. and acenaphthylene were the second dominant compound group in order from both facilities. BC oil boiler had relatively high concentration of pyrene compared to LNG boiler that had high concentration of fluorene and did not detect pyrene. The sum of 16 PAH concentrations emitted from MSW incinerators after APCD (air pollution control device) was three times higher than those from MSW incinerators bcfore APCD. However, the concentrations of more than 4-ring PAH compounds (e.g., benzo (a)anthracene) before APCD were higher than those after APCD. This fact implies that PAHs generated by combustion process are eliminated in APCD and they are continuously produced in stack or atmosphere by PAHs precursors.
폴리에스테르 섬유 감량시스템용 프로세서 타이트레이터 개발
조진호,이흥락,이종현,김명남,구성모,김무영,진경찬,유병희,강민수,김국진 경북대학교 센서기술연구소 1993 연차보고서 Vol.1993 No.-
폴리에스테르 섬유 감량시스템의 제어를 위해서는 처리조 내에서 감량되는 섬유가 목표 감량치에 도달했는지를 판단해 주는 장치가 필요하다. 본 연구에서는 가성소다용액의 초농도 및 섬유 감량 정도의 정확한 측정과 감량 종료시간의 산출 및 이에 따른 종료신호를 발생할 수 있는 폴리에스테르 섬유 감량기 전용의 자동적정장치를 개발하였다. To control caustic soda treatment system for the polyester fabric reduction, we need the device to determine that the fabric has been arrived target reduction value. In this study, we develope an automatic process titrator for the caustic soda treatment system. Major functions of the target titrating system are accurate measurements of the caustic soda concentration and then producing the end point signal for caustic soda treatment system.
Min-Mo Koo,Seok-Myeong Jang,Yu-Seop Park,Hyung-Il Park,Jang-Young Choi IEEE 2013 IEEE transactions on magnetics Vol.49 No.7
<P>In this study, the design for a direct-drive permanent magnet (PM) wind power generator is presented, and its characteristics are analyzed based on analytical approach. In order to confirm their influence on the torque ripple characteristics, both the shape design and the skew effects of the PM are thoroughly studied. In particular, we performed an analytically based electromagnetic field analysis in order to investigate the influence of the AC/DC load conditions on our model. By manufacturing a model using an experimental construction setup, we validate the results of our analytical approach.</P>
Koo, Ja-Choon,Chun, Hyun-Jin,Park, Hyeong-Cheol,Kim, Min-Chul,Koo, Yoon-Duck,Koo, Seong-Cheol,Ok, Hyun-Mi,Park, Soo-Jeong,Lee, Sung-Ho,Yun, Dae-Jin,Lim, Chae-Oh,Bahk, Jeong-Dong,Lee, Sang-Yeol,Cho, Mo Plant molecular biology and biotechnology research 2002 Plant molecular biology and biotechnology research Vol.2002 No.-
Two hevein-like peptides from the seed of Pharbitis nil, designated Pharbitis nil antimicrobial peptide 1 (Pn-AMP1) and Pn-AMP2, had been purified previously. Both exhibit potent in vitro antifungal activity against a broad spectrum of phytopathogenic fungi. We now report the isolation of two cDNA clones, designated pnAMP-h1 and pnAMP-h2, and the corresponding genomic clones encoding these protein suggests that the peptides are produced as a prepropeptide consisting of and N-terminal signal peptide, the mature protein and C-terminal domains. The transcripts of the two genes are accumulated seed-specifically, and the maximum transcripts are observed in the mid-to-late stage of seed development. Constitutive over-expression of the pnAMP-h2 cDNA in transgenic tobacco under the control of the cauliflower mosaic virus 35S promoter conferred enhanced resistance against the oomycete Phytophthora parasitica, the causal agent of black shank disease. Thus the Pn-AMPs may play a role in the protection of seeds and may
Koo, Min-Mo,Choi, Jang-Young,Hong, Keyyong,Lee, Kangsu IEEE 2015 IEEE transactions on magnetics Vol.51 No.11
<P>In this paper, eddy-current loss in permanent magnets (PMs) due to the armature reaction field of a PM synchronous machine was analyzed. Various techniques, including numerical techniques such as finite element analysis (FEA), enable the accurate prediction and analysis of magnetic field distribution with saturation effects. Furthermore, the eddy-current loss can be easily analyzed using a commercial software. 3-D FEA is essential when considering the stator skew effect. In particular, the influence of time harmonics in armature current and space harmonics due to distributed magnetomotive force on the eddy current loss is thoroughly investigated and discussed on the basis of 3-D FEA.</P>