분사법에 의한 탄산칼슘 제조

신보철,한상오,김주호,송지훈,송근호,이광래 강원대학교 석재복합신소재제품연구센터 2001 석재연 논문집 Vol.6 No.-

본 연구는 탄산가스화법에 의한 탄산칼슘 입자 제조 공정에 있어서, 탄산가스로 채워진 반응기에 수산화칼슘 슬러리를 분사하는 방법으로 탄산칼슘 입자를 제조하였다. 수산화 칼슘의 농도(0.25~1.0wt%), 분사압력(0.5kgf /㎠~1.5kgf /㎠) 및 반응기 온도(20℃, 28℃)의 변화에 따른 생성된 탄산칼슘을 관찰하였다. 수산화 칼슘의 농도가 비교적 높으면(0.75wt%, 1.0wt%), 생성물의 pH와 전도도는 높게 나타났다. 분사압력에 의한 탄산칼슘 제조의 변화는 분사압력이 높아질수록(1.5kgf /㎠), pH와 전도도는 높게 측정되었다. 그러나, 수산화 칼슘의 농도와 분사압력의 변화가 탄산칼슘의 입자크기, 형태, 결정구조에 영향을 미치지는 않았다. 반응기의 온도가 28℃에서 생성된 탄산칼슘은 1.0㎛이하의 칼사이트 상 입자가 제조되었으며, 20℃에서 생성된 탄산칼슘은 0.5㎛이하의 칼사이트 상 입자가 제조되었다. 반응기의 온도가 낮아질수록 탄산칼슘 입자의 크기가 작아짐을 알 수 있었다. For the preparation of calcium carbonate particles from aqueous Ca(OH)2 slurry, carbonation reaction of aqueous Ca(OH)2 slurry was carried out by spouting the aqueous slurry of Ca(OH)2 into reactor filled with CO2 gas. The concentration of Ca(OH)2 varies from 0.25wt% to 1.0wt%, nozzle pressure from 0.5kgf /㎠ to 1.5kgf /㎠, and reactor temperature were set at 20℃ and 28℃. With relatively high concentration of 0.75wt% and 1.0wt% of Ca(OH)2, pH and conductivity of product-stream were observed high value. High pH and conductivity were observed at high nozzle pressure of 1.5kgf /㎠. The concentration of Ca(OH)2 and nozzle pressure, however, did not change the particle size and shape of calcium carbonate synthesized by carbonation reaction. The reaction temperature affected particle size. At reactor temperatures of 28℃ and 20℃, the particle sizes were about 1.0㎛ and 0.5㎛, respectively. Crystal structure of calcium calcium carbonate was of calcite. When reactor temperature was lower, the size of calcium carbonate particle was smaller.

The Computer Algebra Systems in Mathematics Education : A Review of Recent Research

Kwon, Oh-Nam,Shin, Eun-Ju,Shon, Bo-Kyung 이화여자대학교 교과교육연구소 2001 East west education Vol.18 No.-

This study examines the potential role for Computer Algebra Systems(CAS) in such an educational context, particularly their potential to get students more engaged in the learning of mathematics as well as to reduce the "strangle hold" of prerequisite algebraic skills, in courses such as functions, introductory calculus. What is the present status of and near-future outlook for computer algebra in Korean secondary schools? The answer that arises from this review of available fact is: bright with promise, but still dim. Several recent developments have set the stage for an acceleration in the dissemination rate for CAS to high schools. However, this review of some past and present conditions indicates that many years will pass before computer algebra is impacting high school mathematics as much as hand-held calculators are doing now.

석탄회를 이용한 석탄광산 폐기물의 안정화 효율성 평가

오세진(Se-Jin Oh),김성철(Sung-Chul Kim),고주인(Ju-In Ko),이진수(Jin-Soo Lee),양재의(Jae E. Yang) 한국토양비료학회 2011 한국토양비료학회지 Vol.44 No.6

본 연구는 다량의 중금속을 함유하는 폐석탄 광산에 적치된 폐석으로부터 발생하는 침출수의 안정화를 위해 석탄회를 안정화제로서의 적용성을 평가하는데 목적이 있다. 석탄폐석에 석탄회를 적용하여 컬럼시험을 수행한 결과는 다음과 같다. 1) 석탄회의 pH는 비산재와 바닥재가 각각 11.1, 9.7의 강알칼리성을 갖는 것으로 나타나 강산성 조건의 폐석 (pH 3.5)를 교정하였으며 유기물을 비롯하여 식물생장에 필요한 영양소인 인산, 칼슘 등을 함유하는 것으로 나타나 폐석과 혼합할 경우 비옥도가 개선될 수 있을 것으로 판단된다. 2) 폐석만을 충진한 컬럼에서 발생하는 침출수의 pH는 3.5~4.0의 수준을 시험기간 동안 지속적으로 유지하는 것으로 나타나지만, 석탄회의 처리량에 따라 40% (pH 5.0~6.0) 〉 20% (pH 4.5)로 나타나고, 동일 처리량 (40%)의 처리방법에 따른 효율성은 완전혼합 (pH& & 5.0~6.0) 방법이 층위처리 (pH 4.0~4.5)에 비해 pH 상승효과가 높은 것으로 조사되었다. 3) 침출수의 Ca과 Mg의 함량은 4 pore volume까지 빠르게 용탈되다 그 이후부터 안정화 되었으며 석탄회에서 용탈된 Ca과 Mg의 영향으로 폐석에 함유되었던 Cu, Pb, As, 및 Al 등이 탄산이온 (CO₃<SUP>2-</SUP>) 또는 수산화이온 (OH-)과 불용성 화합물을 형성하여 안정화 되는 것으로 사료된다. 4) 철의 용존함유량에 대한 분석결과 석탄회 처리구의 용존량이 석탄회를 40% 층위처리한 처리구를 제외하고 대조구에 비해 약 8-74% 정도 감소하는 것으로 조사 되었다. 5) 석탄회를 이용한 폐석의 중화 및 철의 용존량 감소 효율성을 평가한 결과 폐석의 중화 효율성은 석탄회를 40% 완전혼합한 경우 가장 높았으며 철의 용존량 감소 효율성은 석탄회를 20% 완전혼합한 경우가 가장 좋은 것으로 조사되었다. 따라서 석탄회를 이용하여 현장에서 폐석을 처리할 경우 약 20-40%의 석탄회를 처리해야 높은 효율성을 얻을 수 있을것으로 사료된다. In this study, coal combustion ash (CCA) was evaluated for its stabilization effect on acidic mine waste with column experiment. Total of six treatments were installed depending on mixing ratio between coal wastes and CCA (0, 20, 40%) and mixing method (completely mixing and layered). Artificial acidic rain (pH 5.6) was used for feeding solution with flow rate of 0.05 mL min<SUP>-1</SUP>. Result showed that higher pH of leachate was observed as more CCA was mixed. The highest pH in leachate was measured when 40% of CCA was mixed with coal waste (pH of 5.8). Also, complete mixing with CCA and coal waste was more effective to increase the pH of leachate than layered treatment. Regarding the reduction of soluble Fe amount, the highest efficiency (78%) was observed when 20% of coal ash was completely mixed with mine waste. Based on those result, optimum mixing ratio of coal ash with mine waste can be ranged 20-40% depending on environmental circumstances in the field.

방사선 수술시 경험적 표적 근사화에 근거한 최적화 방법 개선

오승종,최경식,송주영,서태석,Oh Seungjong,Choi Kyoung-Sik,Song Ju-Young,Suh Tae-Suk 한국의학물리학회 2005 의학물리 Vol.16 No.4

정위적 방사선수술(stereotactic radiosurgery, SRS)은 한번에 고선량의 방사선을 병변에 조사하는 방사선 치료법으로 단 한번의 조사로 고선량의 방사선이 환자에게 주어지므로 정확한 수술계획의 수립이 필요하다. 현재, 수술계획은 수술계획자에 의해 직접 시행착오를 거듭하며 수립되고 있으며 이로 인해 계획의 재연성과 신뢰성에 문제가 제기되고 있다. 본 연구에서는 경험적 표적 근사화에 근거한 오등의 연구방법을 바탕으로 각 단계를 개선하여 더 나은 수술계획 결과를 얻을 수 있도록 하였다. 주어지는 병소의 다양한 모양을 동일한 높이의 원통을 사용해 근사화하고, 각각의 원통의 중심점의 위치와 지름에 의해 주변의 원통과 하나로 결합시켰다. 그 후 각각의 원통 내에 등선량중심점(Isocenter)을 모사한 구를 미리 정의된 규칙에 의해 채워 나갔다. 두 개의 가상 표적을 이용해 기존 알고리듬과 본 연구에서 개선한 알고리듬을 이용해 최적화를 수행하였다. 그 결과 두 개의 가상 표적에서 PITV (proscription isodose to tumour volume ratio)와 MDPD (maximum dose to prescription dose ratio)의 별다른 차이가 보이지 않았으며, 사용된 구의 수를 각각 $36\%$, $26\%$ 줄일 수 있었다. 원통과 구형을 이용한 이러한 기법은 정위적 방사선 수술시 수술 계획자에게 도움을 줄 수 있을 것으로 생각된다. Stereotactic radiosurgery (SRS) is a technique to deliver a high dose to a target region and a low dose to a critical organ through only one or a few irradiation. The SRS must be planned exactly. Currently the surgery plan is peformed by trial and error method. There are many questions about the reliability and reproducibility of the plan result. This study Improve each step of the Oh's method based on heuristic target shaping to obtain the better result. The target was reconstructed using cylinders with same height and the neighbored cylinders were combined according to the difference of each center and diameter. Then, spheres were packed within each cylinders by the packing rules. Two virtual targets were used to compare this method with Oh's method. As a result, the numbers of isocenter were successfully reduced - more than $35\%$ and $26\%$ - without serious differences of proscription isodose to tumour volume ratio (PITV) and maximum dose to proscription dose ratio (MDPD). This technique using cylinder piling and sphere packing will be a helpful tool to planner in stereotactic radiosurgery.

회분식 반응기에서의 공정변수 변화에 의한 침강성 탄산칼슘 제조

신보철,한상오,김주호,송지훈,송근호,이광래 江原大學校 産業技術硏究所 2001 産業技術硏究 Vol.21 No.B

For the preparation of calcium carbonate particles from aqueous Ca(OH)2 slurry, carbonation reaction of aqueous Ca(OH)2 slurry was carried out by batch method the CO2 into reactor filled with aqueous slurry of Ca(OH)2. The concentration of Ca(OH)2 varies from 1.00 to 7.00wt%, reactor temperature at 20 and 40℃, and reactor pressure from atmospheric pressure to 6.0kgf/cm2. Crystal structure of calcium carbonate was of calcite, the particle size were about 0.05 ∼2.0㎛, and the particle shape was cubic and spindle. When reactor temperature was higher, particle size of calcium carbonate was bigger and particle share was varied, but reaction rate was increased. When reactor pressure was higher, particle size of calcium carbonate was smaller, particle shape was cubic, and reaction ramie was increased.

Reactive perforating collagenosis with leukocytoclastic vasculitis

( Ju Yun Woo ),( So Min Lyu ),( Seung Hyun Cheong ),( Ji Yeon Byun ),( Hae Young Choi ),( Chee Won Oh1 ) 대한피부과학회 2012 대한피부과학회 학술발표대회집 Vol.64 No.1

관행농법과 유기농법의 비교연구

오주성,박흥식,정순재,정원복,진동호 東亞大學校 大學院 2000 大學院論文集 Vol.25 No.-

This study focuses on Comparative of conventional Agriculture and Organic Farming Among various kinds of environmentally sound farming practices the organic and Conventional Agriculture practices are chosen for this study. The main objective of this study is to evaluate the technological systems of organic farming practice in order to find the possibility of extending such technological system to the general farmers. Compared with the general farming practices, the organic farming requires many special technologies. Among them, technologies relating to compost making, pest, insect and weed control are different from those fo general farming practices. New technologies for the improvement of organic farming practices are developed or and imported from abroad by the organic farming association. As far as technology development for the organic farming, many research organizations between the goals of technology development of the conventional and organic farming system. In other words, land productivity of the organic farming technological system is lower than that of the conventional farming technological system.

인터넷 광고의 활성화 방안

오성동,류주식 朝鮮大學校 2002 經營經濟硏究 = Management and economics research Vol.25 No.1

東西洋의 二大提督 : 忠武公과 Nelson Yi Sun-sin and Horatio Nelson

吳主煥 慶北大學校 文理科大學 1974 文理學叢 Vol.2 No.-

While Admiral Yi Sun-sin, hero of Im-jin war(1592-98), has been worshipped as a great national hero, the hero-worship might be in danger of degenerating into national parochailism and chauvinism, if it would be connected with darker aspect of nationalism. This writer, therefore, has thought it necessary to make a study of Admiral Yi in world perpective to correct (aufheben) some blind patriotism, egocentrism on the one hand and foreign-oriented mind on the other and to examine his relative greatness and proper position in naval history of the world. This aticle is a comparative study of Admiral Yi with Horatio Nelson, hero of Trafalgar(1805), in dealing with their respective genius and ideas, great achievements (three major naval battles of both) and characters. etc. The following may be stated as a summary of this article; Through this comparisons, simiralities and differences between Admiral Nelson and Yi are observed. Their similarities are found in their staratigies of annihilation, patriotism, and great naval victories at the cost of life, and their differences are in personal character, scholarship and various non-militray activities. The Admirals ennobled the idea of duty, chose the high path of patriotism pursuing it to end, and ensured fo their fatherlands mastery of seas which was unchallenged for more than a century. Both of them left the same legacy of heroism and devotion to their countries that can hardly be excelled. To be sure, Nelson was the greatest of sea heroes in the world history and superman on the quarterdeck. However, he was a man with many of human frailities. In contrast with Nelson, Admiral Yi was not only a fleet commander but also a great scientist, eminent scholar, well-known filial devotionist and virtuous man of character. He was a fleet commander of an effiminate country who had to play many-sided roles in construction ships for himself, manufacturing arms, recruiting seamen, producing provisions and providing assylums for refugees. In consideration of his many-sided genius and roles, this writer believes that Admiral Yi may be no less greater than Nelson whose fame seems to be owed much to Great Britain as a powerful naval empire and egocentric western history. Consequently, he might say that Admiral Yi deserves to be placed in the same position in Asian history as Nelson in western history.

변이주인 Trichoderma reesei YC-3156이 생산하는 Cellulase에 관한 연구

오두환,안순철,유주현,허남윤 연세대학교 산업기술연구소 1987 논문집 Vol.19 No.2

After the treatment 15 strains of Trichoderma sp. and 4 isolates with N-methyl-N´-nitro-nitrosoguanidine, T. reesei YC-3156 among the mutants showed the highest cellulase activity. The Avicelase of T. reesei YC-3156 was purified by 70% ammonium sulfate fractionation, dialysis, DEAE-Sepharose column chromatography and Sephadex G-100 Gel-filtration. With the result of the procedures, its purification degree was 13 folds, yield 9.3% and specific activity 0.9 unit/mg. The homogeneity and the molecular weights of the purified Avicelase were determined by SDS-polyacrylamide gel electrophoresis, it was electrophoretically homogeneous and showed the molecular weights of 46,000-48,000. The purified Avicelase was stable between pH 4.0 and pH 5.0 and it was inactivated rapidly above 60℃.