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.

불완전 가와사끼병에서 NT-proBNP의 진단적 역할

이동원,김여향,현명철,권태찬,이상범,Lee, Dong-Won,Kim, Yeo-Hyang,Hyun, Myung-Chul,Kwon, Tae-Chan,Lee, Sang-Bum 대한소아청소년과학회 2010 Clinical and Experimental Pediatrics (CEP) Vol.53 No.4

목 적: 지속적인 발열과 3개 이하의 가와사끼병 진단 기준을 만족하는 환자군에서 불완전 가와사끼병을 감별하는데 있어 NT-proBNP가 가지는 진단적 의미를 살펴보고자 하였다. 방 법: 2008년 1월부터 2009년 6월까지 가와사끼병으로 진단 및 치료 받은 환자 96명을 대상으로 하였다. 진단은 입원 당일 열을 포함한 가와사끼병의 고전적인 진단 기준에 따랐고, 진단 기준의 만족 정도에 따라서 완전 가와사끼병 환자군과 불완전 가와사끼병 환자군으로 구분하였으며, NT-proBNP를 포함한 혈액검사를 시행하였다. 지속되는 열과 함께 3개 미만의 진단 기준을 만족하였지만 임상 경과와 여러 검사들을 통해 환자 19명을 대조군으로 하여 분석하였다. 결 과: 96명의 가와사끼병 환자 중 고전적인 진단 기준을 3가지 이하로 만족한 불완전 가와사끼병 환자는 33명으로 전체 가와사끼병 환자의 34% 였다. 임상 양상으로 구강 점막의 변화와 안검 충혈이 가장 많았는데 완전 가와사끼병에 비해 발생 빈도는 적었다(76% vs 98%, 76% vs 90%). 불완전 가와사끼병 환자의 NT-proBNP는 대조군에 비해 유의하게 높았으며($1407.7{\pm}1633.5pg/mL$ vs $126.2{\pm}135.5pg/mL$, $P$<0.001), cutoff value를 158 pg/mL으로 하였을 때 민감도 81%, 특이도 74% 로 C 반응성 단백 ${\geq}3mg/dL$의 민감도 74%, 특이도 68% 보다 높았지만, 적혈구 침강 속도 ${\geq}40mm/hr$의 민감도 70%, 특이도 84%로 특이도에서 적혈구 침강 속도보다 낮았다. 결 론: 지속되는 열, 안검 충혈, 구강 점막의 변화가 있어 불완전 가와사끼병으로 의심해야 하는 환자에서 NT-proBNP 검사를 시행하고 진단에 이용하는 것이 가와사끼병의 빠른 진단과 치료에 도움이 될 것이다. Purpose : To determine the efficacy of the N-terminal fragment of B-type natriuretic peptide (NT-proBNP) as a useful diagnostic method in children with incomplete Kawasaki disease (KD). Methods : Ninety-six patients who were diagnosed as having KD between January 2008 and June 2009 were enrolled in the study. American Heart Association recommendations for diagnosis were used, and patients were divided into the complete KD and incomplete KD groups. Blood tests including NT-proBNP were performed on admission day. Nineteen patients who had other febrile diseases other than KD were enrolled as control. Results : Thirty-three patients (34%) had incomplete KD. Change in the lips and oral cavity and conjunctivitis were the most common clinical features, but their frequency was lower than complete KD (76% vs 98%, 76% vs 90%). Patients with incomplete KD exhibited significantly higher NT-proBNP level than that of control ($1,407.7{\pm}1633.5pg/mL$ vs $126.2{\pm}135.5pg/mL$, $P$<0.001). An NT-proBNP cutoff value of 158 pg/mL provided a sensitivity of 81% and a specificity of 74% for diagnosis of incomplete KD. Conclusion : NT-proBNP assay can be clinically useful for the diagnosis of incomplete KD, if the patient has persistent fever, change in the lips and oral cavity, and conjunctivitis, and if the patient with those symptoms is suspected to have incomplete KD.

3상 교류전원 LED 램프의 광 플리커

이동원,김병철,Lee, Dong Won,Kim, Byungcheul 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.4

This study describes that light flicker of LED lamp is improved by placing an AC-powered LED block in each phase of three-phase AC power. Rectified current is considered as an instantaneous luminous flux because the current flowing through the LED block is proportional to the amount of light emitted by the LED block. Percent flicker is calculated simply by modeling the rectified current flowing through the LED block to a triangular wave current. Percent flicker is 100% in single-phase AC powered LED lamp. Percent flicker of the same level as that in an incandescent lamp (6%~14%) is however, achieved if light emission starts before $40^{\circ}$ in each voltage phase of three-phase AC power.

신항만 개발방향 및 효율적 추징방안

이동원,Lee, Dong-Won 한국건설안전협회 1997 建設 安全技術 Vol.25 No.-

금속환원법에 의한 바나듐 분말 추출

이동원,허상현,염종택,왕제필,Lee, Dong-Won,Heo, Sang-Hyun,Yeom, Jong-Taek,Wang, Jei-Pil 한국분말야금학회 2013 한국분말재료학회지 (KPMI) Vol.20 No.1

The extraction of metallic pure vanadium powder from raw oxide has been tried by Mg-reduction. In first stage, $V_2O_5$ powders as initial raw material was reduced by hydrogen gas into $V_2O_3$ phase. $V_2O_3$ powder was reduced in next stage by magnesium gas at 1,073K for 24 hours. After reduction reaction, the MgO component mixed with reduced vanadium powder were dissolved and removed fully in 10% HCl solution for 5 hours at room temperature. The oxygen content and particle size of finally produced vanadium powders were 0.84 wt% and 1 ${\mu}m$, respectively

고역률 LED 구동회로의 효율화에 관한 연구

이동원,김병철,Lee, Dong Won,Kim, Byungcheul 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.8

The rectified voltage supplied to LED lamp is used in load and then the surplus voltage can be produced in LED lighting. In this case, LED lighting is proposed that can recyclable the excess voltage to supply power to the controller.

슬개골 내측 추벽의 양동이 손잡이형 파열 - 증례 보고 -

이동원,하정구,김진구,Lee, Dhong Won,Ha, Jeong Ku,Kim, Jin Goo 대한정형외과스포츠의학회 2011 대한정형외과스포츠의학회지 Vol.10 No.2

슬관절의 추벽은 정상적인 구조물로 인식되고 있으나 외상, 반복적인 손상 등과 같은 유발 인자에 의해 비후되면서 탄력성을 소실하고 병적인 추벽으로 변하면서 증상을 일으키게 된다. 슬개골 내측 추벽 증후군은 슬내장의 주요한 원인으로 이에 대한 많은 연구가 이루어지고 여러 문헌에서 보고되어 왔으나 추벽의 양동이형 손잡이형 파열에 대한 보고는 극히 드물다. 저자들은 슬개골 내측 추벽의 양동이 손잡이형 파열에서 관절경적으로 절제한 증례를 보고하는 바이다. The medial patellar plica may cause symptoms when it becomes thickened and fibrotic because of direct trauma or repetitive sporting activities. The medial plica syndrome has been noticed as one of major causes of internal derangement and well documented in the articles. A few cases of the bucket handle tear of the medial plica are described in liteartures. To our knowledge, however, there have never been reported about it in domestic literatures. We present a case of the bucket handle tear of the medial plica resected by arthroscopic surgery with a review of the relevant articles.

탄탈륨 산화물의 마그네슘 가스환원에 의한 탄탈륨 금속분말 제조

이동원,Lee, Dong-Won 한국분말야금학회 2018 한국분말재료학회지 (KPMI) Vol.25 No.5

Metallic tantalum powder is manufactured by reducing tantalum oxide ($Ta_2O_5$) with magnesium gas at 1,073-1,223 K in a reactor under argon gas. The high thermodynamic stability of magnesium oxide makes the reduction reaction from tantalum oxide into tantalum powder possible. The microstructure after the reduction reaction has the form of a mixture of tantalum and magnesium oxide, and the latter could be entirely eliminated by dissolving in weak hydrochloric acid. The powder size in SEM microstructure for the tantalum powder increases after acid leaching in the range of 50-300 nm, and its internal crystallite sizes are observed to be 11.5 to 24.7 nm with increasing reduction temperatures. Moreover, the optimized reduction temperature is found to be 1,173 K as the minimum oxygen concentration is approximately 1.3 wt.%.

원관내 난류 선회류의 수치해석

이동원,김광용,Lee, D.W.,Kim, K.Y. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.3

Numerical calculations are carried out for the swirling turbulent flow in a pipe. Calculations are made for the flow with swirl parameter of 2.25 and the Reynolds number of 24,300. The turbulence closure models used in these calculations are two different types of Reynolds stress model, and the results are compared with those of $k-{\varepsilon}$ model and the experimental data. The finite volume method is used for the discretization, and the power-law scheme is employed as a numerical scheme. The SIMPLE algorithm is used for velocity-pressure correction. The computational results show that GL model gives the results better than those of SSG model in the predictions of velocity and stress components.

입자 사이즈에 따른 Cu 필름의 에어로졸 성막 거동에 대한 연구

이동원,오종민,Lee, Dong-Won,Oh, Jong-Min 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.4

The effect of particle sizes on the aerosol deposition (AD) of Cu films is investigated in order to understand the deposition behaviors of metal powder during the AD process. The Cu coatings fabricated by using $2{\mu}m$ Cu powders had a dense microstructure, a high deposition rate ($1.6{\pm}0.2{\mu}m/min$), and low resistance ($9.42{\pm}0.4{\mu}{\Omega}{\cdot}cm$) compared to that from using Cu powder with a particle size greater than $5{\mu}m$. Also, from estimating the internal micro-strain of Cu films, the Cu coatings fabricated by using $2{\mu}m$ Cu particles exhibited a high micro-strain value of $3.307{\times}10^{-3}$. On the other hand, the strain of Cu coatings fabricated with $5{\mu}m$ particles was decreased to $2.76{\times}10^{-3}$. These results seem to show that the impacted Cu particles are compressed and flattened by shock waves, and that their bonding is associated with the high internal micro-strain caused by plastic deformation.