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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.%.
이동원,이양,정영우,Lee, Dong Won,Lee, Yang,Chung, Young Woo 영남수학회 2014 East Asian mathematical journal Vol.30 No.4
We can easily see the 'cycloid slide' in the many mathematics and science museums. The educational materials, however, do not give us any mathematical principle. For this reason, we, in this thesis, first study the brachistochrone problem in the history of mathematics, and suggest a method of how to teach the principle using 'the dynamic geometry software GSP5' in order to help students understand the idea that the cycloid is the brachistochrone. Secondly, we examine the origin of the calculus of variations and apply it to prove the brachistochrone problem in order to build up the teachers' background knowledge. This allows us to increase the worth of history of mathematics and recognize how useful the learning is which uses technological tools or materials, and we can expect that the learning which makes use of cycloid slide will be meaningful.
이동원,김부윤,정영우,Lee, Dong Won,Kim, Boo Yoon,Chung, Young Woo 영남수학회 2016 East Asian mathematical journal Vol.32 No.2
There are three subjects in the study. First, after investigating the development process of the method of infinite descent and the reduction to absurdity, we prove them to be equivalent each other. Second, we apply the method of infinite descent to some problems in textbook and compare it with the reduction to absurdity. Finally, we discuss on teaching proofs with the method of infinite descent.
과배란 처치시 우세난포 조절에 의한 한우 수정란 생산성 향상에 관한 연구 II. 과배란 처치 시기에 따른 난소반응
이동원,이병천,황우석,Lee, Dong-won,Lee, Byeong-chun,Hwang, Woo-suk 대한수의학회 2000 大韓獸醫學會誌 Vol.40 No.4
This study was investigated the ovarian response following superovulation treatment at different day of diestrus. The criterion for the presence or absence of a dominant follicle based on their morphological examination. Dominant follicle was puntured 48 hrs before the oneset of superovulation treatment by ultrasonography guided aspiration needle. Superovulation was induced by subcutaneous administration of FSH twice a day for 4 day in a decreasing regimen. There was no significant different between presence of dominont follicle and progesterone concentration/diameter of corpus luteum in HanWoo. Number of corpus luteum of donor after superovulation treatment was not significantly different in FSH administration at day 9, 11 and day 13 of estrus($14.5{\pm}4.5$, $15.5{\pm}5.6$ and $11.0{\pm}5.5$, respectively). But, the diameter of CL was significantly correlate(R2 = 0.757) with progesterone levels on day of superovulatory induction. After 7 days of artificial insemination, the embryos at 7 days were collected by uterine flushing after dominant follicle aspiration and superovulation treatment, and evaluated their quality by morphological criteria. Fifty five embryos with excellent, good and fair grade were transferred into 24 recipient cows. Seventeen offsprings, 1 of triplet, 4 of twins and 6 of singlet, were yield from 10 recipient cow. In conclusion, the present study showed that 1) dominant follicle can be determined by ultrasonography with rectal palpation by morphological evaluations, 2) superovulation response after follicular aspiration was not differ at day 9, 11 and 13 of estrus, 3) dominant follicle did not affect to progesterone concentration and diameter of CL, and 4) diameter of CL was significantly correlate to the level of progesterone concentrations in HanWoo.
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
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.