최소시간 강하선 문제의 실증적·수학적 고찰

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.

설문지를 통한 한국인 아토피피부염 임상병력의 진단적 중요성에 관한 연구

이동원,변대규,김진우 ( Dong Won Lee,Dae Gyoo Byun,Jin Wou Kim ) 대한피부과학회 1997 대한피부과학회지 Vol.35 No.3

Backgroud: Recent studies have shown an incomplete agreement with the previously proposed diagnostic criteria of Hanifin and Rajka for atopic dermatitis(AD). This could be due to ethnic differences in the clinical manifestations of AD. To make a diagnosis of AD with confidence, one has to depend on the history and clinical picture according to race. Objectives : The purpose of the present study was to find out the importance of individual symptoms and histories for the diagnosis of Korean AD by questionnaire. Methods : The frequency of 25 questionnaire items was studied in 130 patients with typical AD (48 childhood, 82 adolescence/adult) compared to that in 198 control subjects (89 childhood, 109 adolescence/adult). Results : Nine items(itchy with bodily heat, itchy when sweating, cholinergic urticaria, miliaria, irritation with fabrics, food reaction, pollen allergy, itch with stress) were shown to be of much diagnostic significance(p<0.001) in childhood AD,otherwise thirteen items(itchy with bodily heat, itchy when sweating, cholinergic urticaria, sense of fever, excessive sweating, miliaria, irritation with cosmetics, irritation with fabrics, irritation prone hands, itchy with woolen clothes, pollen allergy, itch with stress, dermographism) were in adolescent and adult, AD. ConClusion : We found some diagnostic significance of clinical histories in Korean AD patients by questionnaire. We propose that this accessible questionnaire would be an efficient and powerful method with which to obtain new and valid information on AD. (Kor J Dermatol 1997;35(3): 443-445)

화학기상응축공정에 의한 WS₂ 나노입자의 합성 및 특성평가

이동원,김주형,올레그토로츠코,윤중열,김병기,Lee, Dong-Won,Kim, Ju-Hyeong,Tolochko, O.,Yun, Jung-Yeul,Kim, Byung-Kee 한국분말야금학회 2008 한국분말재료학회지 (KPMI) Vol.15 No.4

Nano-sized tungsten disulfide ($WS_2$) powders were synthesized by chemical vapor condensation (CVC) process using tungsten carbonyl ($W(CO)_6$) as precursor and vaporized pure sulfur. Prior to the synthesis of tungsten disulfide nanoparticles, the pure tungsten nanoparticles were produced by same route to define the optimum synthesis parameters, which were then successfully applied to synthesize tungsten disulfide. The influence of experimental parameters on the phase and chemical composition as well as mean size of the particles for the produced pure tungsten and tungsten disulfide nanoparticles, were investigated.

러시아 티타늄계 고융점 화합물 분말합성 신기술

이동원,김병기,Lee, Dong-Won,Kim, Byeong-Gi 재료연구소 2004 機械와 材料 Vol.16 No.1

항만공사와 안전관리

이동원,Lee, Dong-Won 한국건설안전협회 1996 建設 安全技術 Vol.20 No.-

지주막하출혈에 의한 뇌기저동맥의 형태학적 변화에 미치는 양격산화탕(凉膈散火湯)의 효과

이동원,이원철,Lee, Dong-Won,Lee, Won-Chul 대한한의학회 1999 대한한의학회지 Vol.20 No.2

The present study was performed to investigate the effect of Yangkyuksanhoa-tang on the morphological changes of the basilar artery after experimentally induced subarachnoid hemonrrhages(SAH). Yangkyuksanhoa-tang has been used freguently for cerebrovascular accident Sprague Dawley rats weighing between 350-400 g were used. The 6 normal rats and 24 SAH elicited rats were used, The SAH induced by injection of the fresh autologus heart blood (0.3-0.4 ml) into the cisterna magna through the posterior atlanta-occipital membrane, Sample group was given 3.3 ml/kg/day of Yangkyuksanhoa-tang extracts for 2 days after SAH. The experimental animals were killed at 48hrs after SAH. The morphological changes of the arterial walls were examined by light and electron microscopy. Following are the obtained results: 1. In SAH elicited rats, the size of the lumen in basilar artery was diminished by about 45% and the thickness of arterial wall was increased by about 82%. In SAH elicited rats with Yangkyuksanhoa-tang treatment, the size of the lumen in basilar artery was merely diminished by about 18% and the thickness of arterial wall was merely increased by about 19%. 2. In light microscopic examination, the endothelium was swollen into a cuboid shape and the layer of smooth muscle was increased in the basilar artery of SAH elicited rats. In SAH elicited rats with Yangkyuksanhoa-tang treatment, the size of the lumen in basilar artery was enlarged and the thickness was decreased than in SAH elicited rats. The endothelium was flattened into a squamous shape and the layer of smooth muscle was decreased more than in SAH elicited rats. 3. In electron microscopic examination, the endothelial cells with fragmentation nuclei were changed into a cuboid shape and the internal elastic lamina were folded at the basilar artery of SAH elicited rat. The nuclei of smooth muscle cells were changed into a round or crumpled shape. The length of smooth muscle was shorten and thickness was increased. But all kinds of morphologic changes were diminished in SAH elicited rats with Yangkyuksanhoa-tang treatment. Conclusion : Yangkyuksanhoa-tang extracts were effective to treat cerebral vasospasm after experimentally induced subarachnoid hemorrhage in rats.

열화학적 방법에 의한 산소센서용 세리아 나노분말 합성

이동원,최준환,임태수,김용진,Lee Dong-Won,Choi Joon-Hwan,Lim Tae-Soo,Kim Yong-Jin 한국분말야금학회 2006 한국분말재료학회지 (KPMI) Vol.13 No.3

The nanostructured cerium oxide powders were synthesized by spray thermal decomposition process for the use as the raw materials of resistive oxygen sensor. The synthesis routes consisted of 1) spray drying of water based organic solution made from cerium nitrate hydrate ($Ce(NO_3){_3}6H_2O$) and 2) heat treatment of spray dried precursor powders at $400^{\circ}C$ in air atmosphere to remove the volatile components and identically to oxidize the cerium component. The produced powders have shown the loose structure agglomerated with extremely fine cerium oxide particles with about 15 nm and very high specific surface area ($110m^2/g$). The oxygen sensitivity, n ($Log{\propto}Log (P_{O2}/P^o)^{-n}$ and the response time, $t_{90}$ measured at $600^{\circ}C$ in the sample sintered at $1000^{\circ}C$, were about 0.25 and 3 seconds, respectively, which had much higher performances than those known in micron or $100{\sim}200nm$ sized sensors.

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.

화학기상응축법으로 제조된 철 나노분말의 산화저항에 관한 연구

이동원,유지훈,배정현,장태석,김병기,Lee Dong-Won,Yu Ji-Hun,Bae Jeoung-Hyun,Jang Tae-Suk,Kim Byoung-Kee 한국분말야금학회 2005 한국분말재료학회지 (KPMI) Vol.12 No.3

In order to prevent the oxide formation on the surface of nano-size iron particles and thereby to improve the oxidation resistance, iron nanoparticles synthesized by a chemical vapor condensation method were directly soaked in hexadecanethiol solution to coat them with a polymer layer. Oxygen content in the polymer-coated iron nanoparticles was significantly lower than that in air-passivated particles possessing iron-core/oxide-shell structure. Accordingly, oxidation resistance of the polymer-coated particles at an elevated temperature below $130^{\circ}C$ in air was $10\~40$ times higher than that of the air- passivated particles.

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.