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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>
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.
트랙터 부착용 로더 기구부의 기구학적 시뮬레이션 프로그램 개발
이규승,박원엽,노광모,김준호 성균관대학교 생명공학연구소 1999 生命工學硏究 Vol.5 No.1
A loader mechanism mounted on tractor was modeled for kinematic analysis, and a computer simulation program was developed by using Cartesian coordinate approach, in order to remove the burden of routine derivation and computation from the engineer. The results of kinematic analysis was compared with those of a commercial CAD program. The results of this study was summarized as follows. 1. The results of the simulation showed good agreement with results of the commercial CAD program. This program could be used for predicting the kinematic properties of each links on the loader mechanism. 2. The velocity of bucket which affect the performance of loader increased very quickly just before the finishing point of boom operation, and acceleration also increased sharply at this point. Thus it is concluded that when bucket is rolling, maximum reaction force arises. 3. Velocity and acceleration of each links on the loader mechanism changed very quickly when the bucket cylinder started operation.
實科學習 評價方法 改善에 關한 硏究 : 技能面을 中心으로 With reference to skill domain
李時元,鄭模根 釜山敎育大學 1985 부산교육대학 논문집 Vol.21 No.1
The purpose of this study was to analyze the problems of skill evelution coming out in the course of the evelution of practical arts traning ot the scene of primary school and to contrive the models of proper evelution methods as to the skill evelution on the ground of the problems. The investigaton method used for this study was means of questionaires. The results obtaineP are summarized as fallows; 1. The result of sending the questionaire to the teachers who have a lot of experience to do practical arts evelution; a) absolute satisfied techers are 4.8% b) somewhat satisfied ones are 47.1% c) suspicious ones are 4.2% 2. The items which teachers feel difficults in pratical arts evelution; a) the obscurity of evelution criterion establishment is 38.6% b) the lack of proper evelution models is 28% 3. Skill evelution measuring instruments; a) seef-made ones are 36% b) others-made ones are 60.3% 4. When the reason why teachers don't make skill evelutions is asked, the result is as follows; a) the reason for the few chances of practical arts training is 43.2% b) the reason for the lack of proper evelution models is 29.5% In the hight of the above problems, if practical arts training is to be developed as a main role in class in order to meet the educational purpose, an urgent problem is supposed to develop a rational evelution criterion establishment and a proper evelution model, which are essential to pratial arts training evelution.
이종달,김원한,정광수,강창모 영남대학교 공업기술연구소 2001 工業技術硏究所論文集 Vol.29 No.1
This study analyzes the problems about the skid-proof pavement on the curved section in moistening by using PC-Crash, a program for traffic accident reconstruction. 1.As a result of applying to the overall treatment gap type pavement method of construction, it showed that the result was considerably stabilized as 4.47% decreased at the average braking distance and 12.66% decreased at the average lateral skid distance. 2.The overall treatment grooving method showed excellent effects as 3.23% decreased at the average braking distance and 9.42% decreased at the average lateral skid distance compared with the general overall treatment method.
1982년 경북지방 우량아 선발대회에 참가한 영유아의 성장발육상
이원석,구순모,강덕식,이건수 慶北大學校 醫科大學 1982 慶北醫大誌 Vol.23 No.2
1982년 경북지방 우량아 선발대회에 참가한 영유아(9-24개월) 442명을 대상으로 이들의 각종 신체계측치 및 혈청단백량, 비타민 D 결핍상황을 살펴본 결과 다음과 같은 결론을 얻었다. (1) 체중에 있어서 한국표준치 및 일본평균치와 비교하여 남녀 모두 2.11∼3.19kg 1.25-2.25kg 우위에 있었고 신장 역시 4.29-6.75cm 및 2.46-2.73cm 우위에 있었으며 흉위 및 두위에 있어서도 각 0.75-4.48cm, 1.33-4.04cm 및 6.54-2.17cm, 0.1-1.06cm 씩 우위임이 측정되었다. (2) 피부두께 측정치에서 Triceps skin fold thickness가 홍등의 계측치에 비해 남아는 0.40-1.48mm, 여아는 1.41-1.93mm, scapular thickness에서는 남아 2.29-2.44mm, 여아가 2.35-2.83mm우위에 있었다. (3) 상완둘레는 홍등의 계측치보다 남아 2.53-2.77cm, 여아 2.19-2.43cm 우위에 있었다. (4) Hand refractometer를 사용하여 측정한 혈청단백량은 남아평균 7.00gm% 여아 7.08gm%로서 연령별 차이는 없었다. (5) kaup지수 20이상은 남아에서 7.8% 여아 6.3%로 나타났다 (6) 수유방법에서는 모유영양이 가장 많아 50.2%였으며 다음이 혼합, 인공영양의 순서였다. (7) 이유시기는 56.6%가 4-6개월에 시작하여 1년이내에 대부분(98.8%)이 시작한 것으로 나타났다. (8) 헤마토크맅치가 33미만인 빈혈환아는 4.75%였고 약 1/3에서 철분투여가 이루어졌으며 빈혈은 철분투여군에서 3.4%, 비투여군에서 5.4% 발생하였다. (9) 약 1/4에서 비타민 D가 투여되었으며 D 부족증상은 12.7%에서 발견되었고 이들의 대부분이 (80%) 이전에 비타민 D 공급을 받지 못했으며 투여군에서 10%, 비투여군에서 13.6% 나타났다. (10) 본 조사군에서는 과거 5년간에 비해 성장발육(체중, 신장, 흉위, 두위, 상완둘레, 피부두께은 큰 차이가 없으나 비만정도, 빈혈, 비타민 D 부족증상은 많은 감소를 보였다. Authors have conducted a study on 442 infants participated in Kyungpook regional wellbaby contest, held in 1982. After through investigation of several parameters including physical growth (body weight, height, chest and head circumferences), nutritional status (Kaup index, serum protein, hematocrit and signs of vitamin C deficiency), and feeding history, along with comparing this with data obtaind from past 5 years (1976-1980), the following results were obtained. Comparing their body weight, height, chest and head circumferences with Korean children's growth standard(K.S.) and Japanese children's growth standard(J.S.), their body weight were superior to those of K.S(2.11-3.19kg) and J.S(1.25-2.25kg), their height superior to those of K.S(4.29-6.75cm) and J.S(2.46-2.73cm) but no remarkable diference between these data and those obtained from past 5 years. Triceps skin fold thickness and scapular thickness were superior to those of Hong(0.4-1.93mm,2.29-2.83mm), the arm circumference were superior to those of Hong(2.19-2.77mm), too. But no remarkable difference between these data and those obtained from past 5 years were found. Total mean serum protein was 7.0gm% in male infants and 7.08gm% in female infants. Kaup index was over 20 in 7.8% in male infants and 6.3% in female infants. Compared to past 5 years, obesity was found less frequently. Breast milk feeding was the most common form of the infant feeding comparing 50.2%, followed by mixed feeding 29.8%, and bottle feeding in 20%. Weaning was started between 4-6 months of age in 56.6% of infants and the vast majority within 12 months of age (98.9%) About 5% of those infants showed anemia, using the cirteria of anemia as being hematocrit less than 33%. They were found in 3.4% of infants with iron-supplemented group, and 5.4% of infants without iron supplementation. In 12.7% of the infants, there were signs of the vitamin D deficiency including Harrison's groove, rachitic rosary, and pigeon chest. They were found in 10% of infants with vitamin D supplementation and 13.6% of infants without supplementation. Compared to past 5 years, anemia and vitamin D deficiency were found less frequently.
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.
이영자,갈원모,정명진 서울保健大學 1992 論文集 Vol.12 No.1
The purpose of this thesis is to perform a systematic analysis of accident or failure using fault tree technique. The theoretical proceduere of the fault tree analysis explained in detail. A computer program which can be used for the qualitative and quantitative analysis of the fault tree is developed. The software for fault tree is partitioned into two parts. In the first part, the minimal cut sets are obtained by Limnios and Ziani's algorithm. In the second part, the quantitative analysis using the minimal cut sets can be perfomed. When the current sub-system is changed, fault tree construction, qualitative and quantitative analysis for the modified system is accomplished easily. It is expected that this study can be applied in analysing the accident easily, even without specific knowledge, and used in the failure analysis of the complex and enlarged system in various field of industry.