SHS 공정에 의해 제조된 Mo_xW_1-xSi₂ 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.

Effect of post annealing on the microstructure, mechanical properties, and failure of Mo_xW_1-xSi₂ heaters produced by self-propagating high-temperature synthesis

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>

十二變에 대한 考察 : 六元正紀大論을 중심으로

채영진,남호현,이석모,여성원,한성규,이재원,안민식,정헌영,금경수 한국전통의학연구소 2003 한국전통의학지 Vol.13 No.1

The six kinds of natural factors(It refers to wind, cold, summer-heat, dampness, dryness and fire.) is constantly moving to maintain the balance of whole climate of one year. Four seasons are the largest mediation of whole climate of one year. The cold and the heat have the relationship of mutual intervention. The dampness and the dryness have it also. In this process they raise various climate appearance. And that various climate appearance influence the whole lives on the earth. This paper is concerned with the classification of them.

베이커리 제품소비함수 추정

모수원,정승태,김영숙 목포대학교 기업경영연구소 2000 企業經營硏究 Vol.4 No.1

The aim of this paper is to model and estimate the consumption demand for bread and cakes. We employ Engle-Granger two-step cointegration technique techique, Johansen's multivariate cointegration methodology and GPH test, because the model must be stationary to get the accurate predicted values. The empirical results show that our model is stationary as well as mean -reverting. This paper also applies impulse-response functions, variance decompositions and historical decompositions to our model, indicating that the consumption demands for bread and cakes are enogenous to as well as predictable with the income variable.

Productivity Loss of Rheumatoid Arthritis Patients according to the Their Stages of the Disease Activity Score

( Sang-Cheol Bae ),( Jin-Hye Cha ),( Jung-Yoon Choe ),( Sung Jae Choi ),( Soo-Kyung Cho ),( Won-Tae Chung ),( Chung-Il Joung ),( Young-Ok Jung ),( Young Mo Kang ),( Dong-Wook Kim ),( Jinseok Kim ),( Y 대한류마티스학회 2018 대한류마티스학회지 Vol.25 No.2

Objective. Productivity loss was compared by 3-stage of disease activity and associations between higher disease activity and high productivity loss were identified. Methods. Data were extracted from Rheumatoid Arthritis (RA) Patient-reported Outcomes Research, which enrolled 2,000 RA patients (>20-year) on disease-modifying-antirheumatic-drugs (DMARDs) (≥ 6-month) from December 2012 to June 2013. This included 1,457 RA patients with the disease activity score (DAS-28-ESR) in their medical charts. Productivity loss in time and indirect cost was estimated using The World Health Organization Health and Work Performance Questionnaire (HPQ). Baseline characteristics and productivity loss outcomes were compared according to DAS-28-ESR groups. Results. 84.4% were females, 54.2% had low DAS-28-ESR (<3.2), and 38.2% and 7.6% had moderate (3.2∼5.1) and high DAS-28-ESR (>5.1). Patients with moderate to high DAS-28-ESR had higher lost productivity time (LPT) and monthly costs of LPT than those with low DAS-28-ESR (time in hours: 110.0±58.4 vs. 132.4±57.2 vs. 71.5±52.0, p<0.0001; monthly costs of LPT in 1,000 Korean won: 1,097±607 vs. 1,302±554 vs. 741±531, p<0.0001). Multiple regression analyses revealed significant associations with high LPT in high (adjusted odds ratio [OR]=3.87, 95% confidence interval [CI]: 2.18∼6.87) and moderate DAS-28-ESR (adjusted OR=1.88, 95% CI: 1.41∼2.52) compared to low DAS-28-ESR. In addition, positive associations with high monthly costs of LPT were observed in high (adjusted OR=3.45, 95% CI: 1.98∼5.99) and moderate DAS-28-ESR (adjusted OR=1.93, 95% CI: 1.43∼2.54) compared to low DAS-28-ESR. Conclusion. Timely therapeutic strategies should be taken into consideration given that the RA patients with moderate to high DAS-28-ESR showed strong associations with high productivity loss for effective management of RA. (J Rheum Dis 2018;25:122-130)

생쥐 중이와 상기도 점막의 섬모세포운동

정하원,오승하,유원석,이강수,모지훈,전상준,김인상,김종선 대한이비인후과학회 1999 대한이비인후과학회지 두경부외과학 Vol.42 No.9

사상체질과 작업특성간의 실증적 상관관계 연구

윤상원,갈원모 사상체질의학회 2000 사상체질의학회지 Vol.12 No.1

작업자의 기질적 특성, 능력 들을 고려하지 않고 이루어진 작업들은 제조현장의 많은 문제점들이 되고 있으며 이런 결과들은 산업재해 및 직업병의 원인을 제공할 뿐만 아니라 제조경영 관점에서 품질 및 생산성 저하의 결과들을 초래하고 있는 실정이다. 따라서 본 연구에서는 이와 같은 제반 문제점들을 해결하기위해 중소기업의 작업특성과 사상체질간의구명을 시도한다. 체질은 기존의 이론인 사상체질(태양인, 태음인, 소양인, 소음인)을 Qscc Ⅱ와 한의사의 도움으로 실질적인 구분을 실시하고, 체질이론의 공학적응용의 기존문헌을 고찰한다. 또한 본 연구에서는 농기계 전문생산 업체를 중심으로 특정 사상체질의 작업자 중심으로 주요 작업특성을 해석하고 그 결과 작업자의 체질에 따라 작업특성이 다르게 나타남을 알 수 있다 한편, 실증적 연구로서 비디오 카메라로 촬영한 작업현장의 장면을 가상현실장비 및 EEGs를 사용하여 체질변화에 따른 작업자의 뇌파효과를 조사한다. 조사된 뇌파 데이타를 통계분석 처리하여 그 다양한 뇌파변화의 관계성을 보여준다. 최종 연구결과들은 추후 작업특성간의 비교 연구과정을 통해 기업의 생산성향상과 품질증지에 크게 공헌할 것으로 추측된다. We detect lots of problems on the manufacturing spot because of working results done without considering the aptitude and inherited temper(constitution, blood type, male and female) of the worker, and they lead to results not only the occupational disease and the cause of industrial accidents but also quality deterioration and productivity reduction in point of view of manufacturing management. For the purpose of solving these problems, this study is perfomed by grasping the correlation sasang constitutions and job characteristic of small & medium enterprises. We classify sasang constitutions to four types : so-yang-in type, tae-yang-in type, tae-em-in type, so-em-in type by the utilization of QSCCⅡ and the doctor aid of oriental medicine, and also survey differences of classified sasang constitutions with previous studies. This study tries to identify significant features between major jobs resulting from sasang constitution types in a specific small & medium enterprise producing agricultural machinery(a tractor, a combine, etc). The results of this case study indicate that sasang constitution types influenced job types. Under the working conditions that virtual reality scene photographed by video camera are running, also the effects of brain function of each worker using Electroencephalograms(EEGs) are investigated. Electroencephalograms(EEGs) provide much information about the brain function, such as relaxation, concentration, various thoughts and so on. Previous studies reported the appearance of θwaves and an increase in the a waves during psychologically satisfaction conditions. An statistical analysis of experiments conducted shows the various changes of brain waves (a, β, θ, δ waves). By means of these study results, we can identify that sasang constitutions should be applied to contribute much to quality advancement and productivity improvement through a comparative study on the job characteristic.

도시유역 배수 관망체계의 계량형태학적 분석

박상덕,김문모,이원한 연세대학교 산업기술연구소 1991 논문집 Vol.23 No.2

The objective of this study is to analyse the validity of urban drainage systems. Morphometric theory is applied to storm sewer systems of Seoul city for analysing this drainage network morphometrically. As the result, Horton's stream order method is applicable to the urban drainage systems and the validity of the drainage systems is judged and also applying this result to ungaged basin. Same as the rainfall intensity, duration and bifurcation ratio in case of bad drainage systems, the peak flow per unit drainage area is smaller than that of good drainage systems. So, if the bifurcation ratio is large, the flood control is advantageous. Because the shape of the basin effects on the runoff hydrograph, successive study considered to morphometric characteristics of the basin is needed.

무증상의 후두개곡 낭종 환자에서 예기치 못한 어려운 기관내 삽관 1례

이상모,최준석,이철승,김원태,박천희 朝鮮大學校 附設 醫學硏究所 2007 The Medical Journal of Chosun University Vol.32 No.1

Although vallecular cyst is often asymptomatic and harmless to the patient, discovery of large vallecular cyst after induction of anesthesia is a potentially life-threatening problem for thepatient and provides for the anesthesiologist a challenge in airway management. We describe a case of difficult intubation where the laryngeal inlet was obscured by a large vallecular cyst that was discovered during induction of general anesthesia. A 47-year-old man presented for elective laparoscopic colecystectomy due to GB polyp. He had normal mouth opening and neck extension; no mass or distortions of the tongue or neck were observed. Anesthesia and paralysis were induced with 80 ㎎ propofol, alfentanil 0.5 ㎎, midazolam 2.0 ㎎ and rocuromum 50 ㎎. It was noted that ventilation of the lungs via mask was difficult. Despite insertion of an oropharyngeal airway, ventilation proved to be more difficult. Intubation was attempted. Direct laryngoscopy (Macintosh 3 blade) revealed a 3-4 ㎝ tranlucent cyst arising from the left vallecula. The cyst completely obscured the view of epiglottis and vocal cords, preventing intubation despite multiple attempts by three anesthesiologists. StafF anesthesiologist was aspirated cyst using a 16-guage needle, syringe and 20 ㎖ of serous fluid were aspirated from cyst. The epiglottis and vocal cord were then exposed and tracheal intubation was performed easily with a size 7.0 cuffed oral tracheal tube. Anesthesia and the operation then proceeded uneventfully, following laparoscopic colecystectomy, an ENT surgeon removed the cyst.