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.

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.

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>

코발트-니켈 을 함유한 금속폐기물로부터 금속이온 분리

具廣謨,李東鎭 慶一大學校 1999 論文集 Vol.16 No.2

We have carried out two method to isolate cobalt and nikel ion from waste. The first isolation method has been accomplished to the difference in solubility using dimethyl glyoxim. Nikel ion in mixture react with dimethylglyoxim to be pink precipitation and cobalt ion to be yellow colored solution. Pink precipitation is neutral charge nikel complex,〔Ni(dmg)₂〕, and it's structure is identified by IR spectra data. Meanwhile, the solution is negative 〔Co(dmg)₃〕complex ion. And yellow solution converted to purple colored 〔Co(dmg)₂(H₂O)₂〕solution. Another method using column chromatography has also studied. Each metal was reacted with ethylenediamine to be form 〔Ni(en)₃〕²+ and 〔Co(en)₃〕³+ complex respectively ,and then isolate them on column chromatography packed Sp- Sephadex C-25 cation exchang resin. The more the concentration of eluent increase, the more fast comlexes elute. And the cation effect on various eluent was shown as following order in retention volume ; K+〈 NH₄∼ Na+.

The Moderating Role of Locus of Control on the Links between Experiential Motives and Online Game Loyalty

Dong‐,Mo Koo 한국산업경영학회 2008 한국산업경영학회 발표논문집 Vol.2008 No.4

Online games represent a burgeoning market sector with growth potential. The distinctive entertainment‐oriented features of such games provide various experiential motives for users. However, most previous studies have focused on the single dimensional affective motive of online game use. The multi‐dimensional affective motivational aspects of entertainment technologies have been relatively neglected. In addition, previous studies report inconsistent relationships between motives and online game usage. To fill these gaps in the literature, the present study proposes five experiential motives such as concentration, perceived enjoyment, escape, epistemic curiosity, and social affiliation as predictors of intention to play online games. Internal locus of control is also introduced as a moderator in the links between experiential motives and intention. The model is tested with the data from 576 current online game players and the data were gathered from online survey methodology. Structural equation model analysis confirms that three experiential motives with the exception of concentration and epistemic curiosity have a positive effect on intention. In addition, Chi square difference test confirms that internal locus of control has a moderating effect between the links from experiential values such as concentration, perceived enjoyment, and escape to intention. Implications are discussed in conclusion.

소수성 NaY Zeolite의 합성과 탈알루미나의 특성

서동남,하종필,구상모,이해진,김익진 호서대학교 반도체제조장비국산화연구센터 2000 학술대회 자료집 Vol.2000 No.1

NaY형 Zeolite는 현재 그들의 촉매적 특성과 흡착성 그리고 이온 교환성들을 이용하여 산업에 중요하게 사용되어지고 있다. 본 실험은 고온 스팀을 이용한 방법과 산처리에 의한 방법으로 탈알루미나의 효과를 확인하는 실험을 하였다. 먼저 SiO_2/Al_2O_3 몰비가 4∼6인 합성 NaY zeolite를 분위기 소성로에 넣고 증기발생 장치를 이용하여 500℃에서 고온 스팀을 분위기 소성로에서 일정하게 주입하였다. 에에 따른 결과는 탈알루미나 처리 후의 XRF와 BET의 결과로 탈알루미나 처리에 따라서 SiO_2/Al_2O_3의 몰비가 20.6에서 21까지 증가한 것을 알 수 있으며 또한 BET의 결과에서 탈알루미나 처리에 의해서 비표면적이 증가한 것을 확인할 수 있으며 특히 meso pore area의 증가는 탈알루미나에 의해서 zeolite의 골격구조가 일부 파괴되었음을 알 수 있다.

茯笭 人工栽培에 適合한 原木과 種菌 接種量 및 接種方法에 關한 硏究

金成敏,申東一,具漢謨,李武鉉,金善喆 공주대학교산업개발연구소 2000 産業開發硏究 Vol.8 No.-

This study was carried out to improve the culturing method of P. cocos, on saving labor and inoculation amount. Therefore, the result of this experiment was as the following. Proper mycelium growth and density of P. cocos was observed in MCM(mushroom complete medium). In the selection of tree species, pine and larch had better in spawn culture and sclerotia formation condition. In the experiment of pine, Yield was 33.7㎏/3.3㎡. In inoculation amount, conventional method(cross slice inoculation) required 16 ~ 20 bottles/1000cc of spawn. In contrast, short log,drilling inoculation method required 8 ~ 10 bottles/1000cc, 2 ~ 3 bottles/1000cc of spawn, which reduced by 50% and 85 ~ 90% of inoculation respectively. In conventional method, the yield of pine was 23.4㎏/3.3㎡. In the case of drilling and short log inoculation, Yield was 28.7㎏ / 3.3㎡(25㎜ / depth) and 30.1kg / 3.3㎡(35mm / depth), 31.7㎏ / 3.3㎡ respectively, Therefore, short log inoculation was increased by 25% and 35% compared with conventional method. In conclusion, management cost was also saved.

가토에서 일측 요관 부분 및 완전폐색시 신장과 요관의 조직학적 변화

김상현,김용웅,육승모,한동석,노안식,임재성,김홍식,나용길,설종구 충남대학교 의학연구소 2003 충남의대잡지 Vol.30 No.2

This study was designed to clarify histologic changes in the experimental rabbit kidney and ureter after unilateral partial or complete ureteral obstruction. A total of 20 adult white rabbits were divided into 4 subgroups in the partial obstruction followed by 2 weeks, the partial obstruction followed by 4 weeks, the complete obstruction followed by 2 weeks, and the complete obstruction followed by 4 weeks. The normal control group was consisted of 5 adult white rabbits. The kidneys and ureters for light microscopy were fixed in 10% neutral formalin, embedded in paraffin and stained with hematoxylin and eosin. Abnormal histologic fingings showed in ipsilateral kidney and ureter of all subgroups(such as dilatation of uriniferous tubule, focal necrosis and desquamation of epithelium, interstitial fibrosis, glomerular congestion, widening of Bowman's space, dilatation of ureter, epithelial cell atrophy or loss, interstitial fibrosis and interstitial inflammation). These findings were most severe in the group of the complete-obstructed ureter for 4 weeks. No significant changes showed in contralateral ureter of all subgroups. The degree of obstruction was severe and period of obstruction was long, the histological changes in ipsilateral side were severe. Despite of changes in ipsilateral side no abnormal findings showed in contralateral side. We suggest that long term experimental investigation of histologic changes in ipsilateral side and compensatory changes in contralateral side have to be studied.

有機農業의 實態와 發展에 관한 事例 硏究 : 忠南 洪城郡 洪東面 有機農家를 中心으로

尹英相,洪性贊,金成敏,具漢謨,申東一,金昌護,姜熙慶 公州大學校 資源科學硏究所 1997 資源科學硏究論文集 Vol.5 No.-

This study was carried out to improve the organic farming system about crop cultivation, compost production and application, plant diseases & pest control, weed control and marketing system of organic farming products to the case study in Chungnam Hongdong area. Agricultural technologies concerning pest & diseases control, weed control and compost production are not established due to lacks of systemized researches by the agricultural scientist, and agricultural machines profitable to this works had not developed yet. In cropping system, reasonable crop rotation had not conducted. The related cultivation of vegetables on the same ground for a long time cause a various plant disease easily. So crop rotation is a reasonable method about soil nutrient utility and soil disease control. It is a good method that introduce the barley and wheat in this field crop system. Those crop have a long root, so can use the other nutrient against the vegetable. In organic farming products, the safety and quality of products by the National Agricultural Products Inspection Center had not inspected except rice, lettus and apple. Inspection is needed for the development of organic farming and mutual confidence between producer and consumer, because the mutual confidence is a major thing to sustain the organic farming. In products marketing, it is more need for the information of organic farming products. Nowaday most products are marketed in Seoul region, but it is not a good method. To search the consumer in near region is a good method for decrease the cost of conveyance and maintain the quality of products. The varieties of distribution structure of organic farming products are required. The products are sold to department store in large city and the prices are about 30% higher than normal products. But when those are supplied in near region, the prices of those are similar to normal products. Direct transactions in near regions is a good method for decrease the cost of conveyance and strength the mutual confidence between producer and consumer.

표재성 방광암에서 Bacillus Calmette-Guerin 방광 내 주입요법 : 장기적 추적결과 Long-term Follow up Results

김용웅,왕세환,육승모,한동석,노안식,나용길,설종구 충남대학교 의학연구소 2003 충남의대잡지 Vol.30 No.2

To evaluated the results of long-term follow up of superficial bladder cancer patients who were treated with transurethral resection and intravesical BCG therapy. Between April 1989 and December 1997, 65 patients with superficial bladder cancer were treated with TUR-B(Transurethral resection of bladder tumor) and intravesical BCG instillation, and follow-up was performed for 5 years longer, and the mean follow-up duration was 82 months. Of 65 patients, pathologic stage were Ta in 17 cases and T1 in 48 cases and grade were G Ⅰ in 22 cases, G Ⅱ in 35 cases and G Ⅲ in 8 cases. The tumor recurred in 22(33.8%) at the median of 21.8 months and the tumor progressed in 9(13.8%) at the median of 20.8 months. Most of the recurrences and progression were within 3 year(838 and 77%). Progression is more likely in higher grade(G Ⅱ, G Ⅲ) and higher stage(T1). The complete response rate after first and second courses of BCG therapy were 53% and 73% and the 5 and 10 year disease specific survival rates were 89.5 and 78% respectively. The complete response rate after first and second courses of BCG therapywere 53% and 73%. Most of recurrences and progressions were within 3 years of the BCG therapy, but some cases occured after 5 years. Therefore, close long-term follow up is needed.