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.

탄닌에 의한 견섬유의 증량

남성우,정인모 成均館大學校 科學技術硏究所 1994 論文集 Vol.45 No.2

The studies were performed to investigate the optimum condition for tannin processing of silk by use of Chiness Gallotannin and synthesized tannic acid, which was aimed at weighting. 1. It was found that the concentration of tannin solution for the efficient weighting of processed silk was 30gr/l of Chiness Gallotannin and 15gr/l of tannic acid. The optimum temperature and time for tannin treatment were 80℃, 60 minutes and the optimum acidity of tannin solution pH 2 to 3. 2. In dyeing the tannin treated silk by Acid Orange II , the dyeing temperature of 60℃ and dyeing time of 90 minutes were appropriate for the desorption control used for weighting of silk. 3. The colour differences of dyed silk fabric by soaping could be remarkably narrowed by tannin treatment, resulting in improving the washing fastness of tannin treated silk by two grade more than that of untreated one. 4. The light fastness of tannin treated silk could be drastically improved by reducing the dye - loss of dyed silk fabric which was coused from the ultraviolet irradiation. 5. The rubbing fastness and water repellency of tannin treated silk was at the same level with that of untreated one. However, the drape coefficiency of tannin treated silk was decreased more than that of untreated one, which is closely related with fabric softness and dressing appearence.

천연염료에 의한 견섬유 염색

남성우,정인모 成均館大學校 科學技術硏究所 1994 論文集 Vol.45 No.2

The study was carried out to identify hue, value and chroma of silk fabric dyed with several kinds of vegetable dyes according to Munsell renotation system and to disclose the colour fastness of dyed silk fabric against laundary, perspiration and light The extraction of tannic leaves for dyeing silk was more effective in alkaline(pH 9.5) than in acidic(pH 3.5) or neutral solution. The optimum temperature and time for extraction of tannic leaves was around boiling point and 60 rains for deep colouring of silk. The colour fastness of silk dyed with extractions of tannic leaves through mordanting with ferrous and cupric sulfate was as high as 4 to 5 grade. It was revealed that the paddy clay was effective as a natural mordant for dyeing silk, though it developed thinner colour than that of ferrous sulfate.

우울증과 알코올중독간의 상관성에 대한 메타분석

김상아,남정모,박웅섭 大韓神經精神醫學會 2005 신경정신의학 Vol.44 No.1

Objectives : This study was designed to integrate the results of community based studies which assessed a relationship between depression and alcoholism by meta-analysis. Methods : We identified the previons studies and included in meta-analysis by searching MEDLINE. Overall, 21 results of the studies for relationship between depression and alcoholism were selected for quantitative meta-analysis. Before the integra-tion of the each effect size of the relationship between depression and alcoholism, a homogeneity test was conducted. For the publication bias, we also conducted the analyses of funnel plot, normal quantile plot, rank correlation test and the fail-safe n. Results : We used the random effect model to estimate the overall effect size, because the homogeneity of studies was rejected in a fixed effect model. Our quantitative meta-analysis yielded that integrated odds ratio between depression and alcoholism was 2.42 (95% C.I. 1.98-2.97). From the results of analyses of the publication bias, the probability of publication bias is consideredlow. Conclusion : The published evidences suggested that there may be a significant positive relationship between depression and alcoholism.

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.

電氣相似模型에 依한 흙속의 浸透流 解析

權武男,具賢謨,李相昊,李錫健 慶北大學校 1989 論文集 Vol.47 No.-

This study was performed to evaluate the usefulness of the electrical analogue model in porous medium. Experimental values by the electrical analogue models were compared with those by the sand models and theoretical values by the fragment method. The results obtained are as follows: 1. The flow lines into the sand model were changed according to rising the upstream water level but those of the electrical analogue model weren't changed, and the equipotential lines were revealed to be almost same in the two kinds of models above. 2. The seepage quantities by the fragment method and the electrical analogue model were a little more than those by the sand model. 3. The exit gradients by the fragment method were steeper than those by the sand model and the electrical analogue model. 4. The seepage quantities were increased in proportion to the increment of the exit gradients. By means of the results above, it may be given as a conclusion that the electrical analogue model test is more useful than the sand model test for appling to seepage flow in the field condition, because the electrical analogue model test is more accurate and simpler. Then, the electrical analogue model test will be able to apply to the three-dimension seepage flow problems.

Sandblasted large grit, acid etched 표면처리에 따른 교정용 미니 임플랜트의 제거회전력에 관한 연구

오남희,김성훈,국윤아,이근혜,강윤구,모성서 대한치과교정학회 2006 대한치과교정학회지 Vol.36 No.5

Sandblasted large grit, acid etched(SLA) 표면처리 된 교정용 미니 임플랜트와 평활면을 가진 교정용 미니 임플랜트 사이에 제거회전력과 조직학적 소견을 통해 표면처리된 교정용 임플랜트의 임상적 가능성에 대하여 알아보고자 하였다. 실험재료로는 길이가 9.5 mm, 외경이 1.8 mm인 custom made, screw shaped, titanium implants가 사용되었다. 미니 임플랜트는 두개의 군으로 분류되었는데 SLA군은 20개의 SLA 표면처리된 미니 임플랜트이었고, 평활면군은 크기와 형태가 같지만 SLA처리공정이 생략되어 제작된 20개의 미니 임플랜트로 구성되었다. 이들은 10마리 가토의 경골에 식립되었다. 각각의 가토의 우측 경골에는 SLA군의 미니 임플랜트 2개가 식립되었고, 좌측 경골에는 평활면군의 미니 임플랜트 2개가 식립되었다. 각 군에는 식립 직후 Ni-Ti coil spring에 의해 약 150 g의 지속적인 견인력이 주어졌다. 식립 6주 후에 10마리의 가토를 희생하였고, 안정된 상태에서 Ni-Ti coil spring을 제거하였으며 digital torque gauge를 이용하여 제거 회전력을 측정하였다. 식립 6주 후에 SLA군의 경우 (8.29 Ncm) 평활면군 (3.34 Ncm)에 비해 더 높은 평균 제거회전력을 나타내었고 조직학적 소견에서도 screw 하방에서의 신생골 형성이 관찰되었다. SLA 표면처리된 미니 임플랜트는 평활면 미니 임플랜트에 비해 좀 더 강한 교정력에 저항할 수 있을 것으로 예상되었다. Objective: The purposes of this study were to evaluate the differences between sand blasted, large grit and acid-etched (SLA) treated mini-implants and smooth surface orthodontic mini-implants in relation to the removal torque as well as the histologic analysis. Methods: Custom-made, screw-shaped, titanium implants with a length of 9.5 mm and an outer diameter of 1.8 mm were divided into 2 groups; the SLA group (20 SLA treated orthodontic mini-implants) and the smooth surface group (20 smooth surface mini-implants), and placed in the tibia metaphysis of 10 rabbits. Each rabbit had 4 mini-implants placed, 2 in each tibia. The right tibia were implanted with the SLA group mini-implants and the left tibia had the smooth group mini-implants placed. Each mini-implant group were immediately applied with a continuous traction force of 150 g using a Ni-Ti coil spring. The rabbits were sacrificed 6 weeks post-surgically. Subsequently, the legs were stabilized, the Ni-Ti coil springs were removed and the mini-implants were removed under reverse torque rotation with a digital torque gauge. Results: 6 weeks after placement, the SLA group presented a higher mean removal torque value (8.29 Ncm) than the smooth group (3.34 Ncm) and histologic analysis revealed a higher new bone formation aspect along the screw in the SLA group. Conclusion: Results of this study indicates that SLA treated mini-implants may endure higher orthodontic forces without loosening.

국내에서 유행하는 HIV의 전파 경로에 따른 Subtype 분포

이주실,남정구,김성순,강춘,최병선,김옥진,박미선,성봉모,서순덕,전수경,변승옥,신영오,조해월 대한감염학회 2001 감염 Vol.33 No.5

Background : Previous data have been reported that subtype B is prevalent in South Korea, but neither the extent nor the proportion of subtypes could be evaluated. This study was designed to analyze the distribution of HIV-1 subtypes, temporal instructions and transmission dynamics between epidemiological groups. Methods : 1,280 Koreans had been diagnosed as HIV seropositive during the period 1985 to 2000. Among them, 134 individuals were selected for this molecular epidemiological study. 134 DNAs were isolated from uncultured or cultured peripheral blood mononuclear cells. V3-V5 (0.7 kb) fragment of HIV-1 env gene was amplified by nested polymerase chain reaction and was sequenced. Results : HIV-1 isolates from thirty-seven homosexuals were all subtype B (100%). On the other hand, 66 isolates from 94 heterosexuals were subtype B (70%) and 28 were non B subtypes (30% : 13 A, 4 C, 2 D, 8 E , 1 G). Only subtype B strains were isolated from 73 males who were infected with HIV inside Korea while 16 B and 20 non B subtype strains were isolated from 36 males who were HIV infected outside of Korea. However, B and non B strains were isolated half and half from females who were infected inside Korea except one. Conclusion : The HIV-1 subtype B strains are prevalent in Korea from the early HIV infection until present in both homo and heterosexuals. Non B strains have been transmitted from men who were infected outside Korea to their spouses and casual partners. So, we need further study to monitor subtype B and non B HIV transmission in epidemiological groups of Korea, (Korean J Infect Dis 33:311∼318, 2001)

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.