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.

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.

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.

연마방법에 따른 탄성의치의 표면거칠기와 Candida albicans의 부착율 변화

오주원,서재민,안승근,박주미,강철균,송광엽 대한치과보철학회 2012 대한치과보철학회지 Vol.50 No.2

연구 목적: 본 연구는 탄성의치 제작 시 주로 사용되는 polyamide를 수종의 연마방법을 사용하여 처리 후 Candida albicans의 부착정도와 표면거칠기를 비교하고자 하였다. 연구 재료 및 방법: 25×15×2 mm 크기의 polyamide 시편을 4군으로 나누어 연마재를 사용하여 기공용 lathe 연마하는 방법(기공실내 연마방법)과 각기 다른 2종의 실리콘 포인트로 진료실내 연마하는 방법, 그리고 실리콘포인트 연마 후 pumice로 연마하는 방법으로 처리하였다. C. albicans의 부착성을 평가하기 위해 5×106 CFU/ml의 C. albicans 현탁액에 시편을 2시간 동안 침적하였고 5회 수세처리 후 한천배지에서 배양하였다. 그리고 주사전자 현미경(JSM-5900, JEOL LTd., Tokyo, Japan) 촬영을 시행하였다. Profilometer (Surf-pak; Kawasaki, Japan)를 이용하여 표면거칠기를 측정하였고 통계처리를 위하여 SPSS 18.0 프로그램을 사용하였다. 일원변량분석으로 비교 분석하였고 사후검증은 C. albicans의 부착성 검증을 위해 Scheffe test를 시행하였으며 표면조도검증을 위해 Tamhane’s T2 test를 시행하였다(α=.01). 결과: 최대 거칠기 값을 보인 군은 2단계의 연마용 버를 사용한 것으로 0.32 ㎛±0.10 값을 나타냈으며, 가장 낮은 거칠기 값을 보인 것은 tungsten carbide를 사용하지 않고 기공용 lathe로만 연마를 한 군으로 0.02 ㎛±0.00의 거칠기 값을 나타냈다. C. albicans 부착 실험에서는 기공용 lathe만을 이용한 연마방법이 가장 적은 부착수를 보였으며 다른 세 군과 유의한 차이가 발견되었다(P<.01). 결론: 표면거칠기 및 미생물 부착능 실험 결과 기공실 연마만을 시행한 경우 유의하게 낮은 거칠기 값과 부착율을 보였다. Pumice로 추가 연마한 군은 진료실연마를 시행한 군에 비해 낮은 거칠기 값을 보였으나 C. albicans 부착에 있어서는 유의한 차이를 보이지 않았다(P>.01). Purpose: The purpose of this study was to compare the effect of 3 chairside polishing methods and laboratory polishing methods on surface roughness and C. albicans adhesion of polyamide denture base. Materials and methods: Using contact profilometer, the surface of polyamide specimens (25×15×2 mm) was studied after conventional polishing without finishing and after chiarside polishing with 2 chiarside polishing kits and chairside-pumice polishing following finishing with tungsten carbide bur. To evaluate the adhesion of C. albicans, C. albicans suspension was overlayed on the test specimen. And the specimens were incubated for 2 hours. Imprint culture method was achieved and counted the colony on the agar plate. Polished polyamide were evaluated using a scanning electron microscope. The statistics were conducted using one-way ANOVA and in case of difference, Scheffe test and Tamhane’s T2 test were used. Results: Surface roughness (Ra) of surfaces polished with 2 chairside polishing kits had higher than conventional polishing and pumice polishing. The highest roughness value was 0.32 ± 0.10 ㎛, and the lowest was 0.02 ± 0.00 ㎛. The adhesion of C. albicans on the specimens polished with chairside polishing group and pumice polishing group were increased than conventional polishing group (P<.01). Conclusion: Conventional laboratory polishing was found to produce the smoothest surface and the lowest adhesion of C. albicans. Two groups polished with Chairside polishing kits were similar with respect to surface roughness. Surface of the specimen polished with pumice is significantly smoother than 2 chairside polishing groups, but the result of C. albicans adhesion is that group polished with pumice was similar with 2 chairside polishing groups (P>.01).

개인용 컴퓨터를 이용한 주파수 및 전압 감시 시스템 개발에 관한 연구

오주환,김민주 영남이공대학 산업기술연구소 1990 産業技術硏究 Vol.4 No.-

This paper presents the development of frequency and voltage monitoring system which necessarily needed on the factory automation. A personal computer system (IBM PC/AT) was used as Host computer and the microcomputer system(Z80A) was used as local processing system for the real time processing. Frequency measurement is done by the counter circuit of the PWM method during a period which installed at each channel for the purpose of reducing the waiting time, and voltage measurement is done by a A/D converter through the multiplexer.

화용론과 전제

오주영 慶星大學校 1987 부산수산대학 논문집 Vol.8 No.4

Although a great number of papers on presuppositions have appeared in recent books and journals, we can't explain the concept of presupposition clearly. However, I think that there are two types of definitions for presupposition : one is a semantic notion, defined in terms of truth and consequence, like (1). (1) A sentence A semantically presupposes another sentence B iff: ⒜ if A is true, then B is true. ⒝ if A is false, then B is true. The other concept of presupposition is a pragmatic notion that the speaker or the hearer rather than the sentence he utters, has presupposition. Under the pragmatic notion, presupposition is the condition that a sentence must be uttered sincerely, as (2). (2) An utterance A pragmatically presupposes a proposition B iff A is appropriate only if B is mutually known by participants. Under these concepts of presupposition, the aim of this paper is to propose that pragmatic presupposition is superior to semantic presupposition in explaining the problem of presupposition cancellation and the projection problem for presuppositions, that is, the problem of explaining how the presuppositions of a complex sentence are related to the presuppositions of the clauses it contains. First, let's look at Langendoen and Savin's proposal(1971) to solve the projection problem for presuppositions. According to this proposal, the set of presuppositions of the complex whole is the simple sum of the parts. In other words, if S?? is a complex sentence containing sentences S₁,S₂,···S?? as constituents, then the presuppositions of S??=the presuppositions of S₁+the presuppositions of S₂···+the presuppositions of S??. For example, the complex sentence (3) holds both the presupposition of its antecedent “Fred has been beating Zelda”and the presupposition of its consequent “She has been unfaithful.”So this proposal is called “cumulative hypothesis ”(by Morgan(1969). But the cumulative hypothesis leads to wrong predictions in cases like (4). (3) If Fred has stopped beating Zelda, then Fred no longer resents Zelda's infidelity. (4) If Jack has children, then all of Jack's children are bald. (n 94) the consequent clause presupposes that. John has children. Nevertheless, the conditional as a whole has no such presupposition. Second, let's turn to Karttunen's proposal(1973, 1974, 1977). Karttunen(1973) distinguished between three different types of complementizable predicates, which he called “plugs”, “holes”, and “filters”as follows: (5) a. Plugs : predicates which block off all the presuppositions of the complement sentence b. Holes : predicates which let all the presuppositions of the complement sentence become presuppositions of the matrix sentence c. Filters : predicates which, under certain conditions, cancel some of the presuppositions of the complement But I think this proposal is very good, but imperfect, because there are some counter- examples for this proposal. I will pick out only one counterexample in (6). In (6), predicate ‘tell’belongs to the above plugs, but the complex sentence (6a) presupposes (6b) which is the presupposition of the complement of (6a). (6) a. The mechanic didn't tell me that my car would never run properly again. b. My car used to run properly. Third, in contrast to the prior theory, Gazdar's proposal(1979 a.b) is as follows: ⒜ all the pontential presuppositions of a sentence are generated as a complete set, as in the original Langendoen and Savin's suggestion. So at this stage, the presuppositions of any complex sentence will consist of all the presuppositions of each of its parts. ⒝ Then a cancelling mechanism is brought into play which culls out of this total set of potential presuppositions all those that will survive to become actual presuppositions of a sentence uttered in a particular context. In one word, we can say that sentences will be associated with potential presuppositions, utterances with actual presuppositions. At any rate, I think Gazdar's proposal has explanatory adequacy and can solve or explain the above problems. In conclusion, semantic theories of presupposition are not viable for the simple reason that semantics is concerned with the specification of invariant stable meanings that can be associated with expressions. Presuppositions are not invariant, not stable, not belong to any orderly semantics, but very changeable to context ; so presuppositions do belong to pragmatics.

요먼리 沒落의 再評價

吳主煥 慶北大學校 1992 論文集 Vol.52 No.-

근세초 英國農村社會의 中核으로서 영국인들이 자부하던 獨立自營農民層 요먼리(yeo-manry)의 成立과 性格에 대해서는 이미 다른 곳에서 취급된 바 있으나 그 沒落問題는 時間的인 거리때문에 취급되지 못하였다. 따라서 요먼리의 沒落問題는 그 成立과 같은 水準에서 취급될 필요가 있다 할 것이다. 뿐만아니라 다른나라들에서는 19세기말 이래 오늘날에 이르기까지 한 社會階層으로서의 存在意義를 상실하게된 요먼리의 沒落문제가 크게 論難의 대상이 되어왔으나 우리나라에선 그에 대한 연구가 전연 업는 실정이다. 그리고 英國 요먼리가 겪었던 歷史的 운명이 現下 우리나라 農民層이 겪고 있는 운명과 흡사하다는 생각을 가지고 있다. 이러한 關心에서 본고에서는 요먼리 沒落에 관한 제문제를 다각적으로 再檢討하므로써 우리나라 農民層에게 닥쳐올 운명을 전망해 보고자 한다. 요먼리 沒落문제는 學者들간에 見解를 달리하여 왔으나 그중에서도 요먼리沒落→산업노동자 創出의 原因을 둘러싼 論難이 그 中心 課題로서 마르크스주의 史家들의 見解와 부르조아 史家들의 見解가 오랫동안 대립되어 왔다. 前者는 議會인클로저(parliamentary enclosure)라는 英國政策의 강제적 수단에 의하여 요먼리는 沒落하여 勞動者로 전락하였다고 주장하는데 대하여 候者는 요먼리는 議會인클로저가 실시되기 이전에 다른 要因들에 의하여 몰락하였으며 산업노동자의 創出은 잉여人口에 의한 자연발생적인 현상이었다고 주장하고 있다. 본고에서는 먼저 요먼리沒落論의 대두와 그 內容을 개관한 다음 그 沒落의 정도와 시기, 요먼리의 性格과 法的 保障度, 沒落의 原因등을 차례로 살펴보고, 끝으로 1960년대 이래 요먼리 沒落문제를 꾸준히 추구해온 체임버스(J. D. Chambers)와 민게이(G. E. Mingay), 그리고 마르크스주의 史家인 라조니크(W. Lazonick)등의 최근의 연구를 중심으로 요먼리沒落 論爭史를 再檢討하여 요먼리와 의회인클로저와의 관계를 밝혀보고자 한다. The time-honoured debate on the decline of yeomanry has been afresh raised by bourgeois historians such as J.D.Chambers, G.E.Mingay and D.S.Landes on the one hand and by Marxist historians such as E.P. Thompson and W.Lazonick and local historian W.G.Hoskins on the other. This article aims to clarify the unexhausted problems of the decline of yeomanry by reexamining of many-sided angles of the decline of yeomanry, that is, its declining period, extent and causes as well as legal protection of copyholders and impact of parliamentary enclosure and population growht on the decline of yeomanry in terms of having an insinght into fortunes of peasants in Korea, who are facing with the storm of Urguay Round. The reappraisal will be summarized as follows; The view on the first half of the 18th century among views on the declinning period seems to gain great support from scholars who have made statistical case studies. This writer, however, feels that this view has to be supplemented by further local studies throughout the country. The extent of its decline amounted to abort 50% during the period from the end of the 17th century to 1750s, when the typical yeomanry has lost its significace of a distinct social class as a historical category. And the causes of the decline were various in short and long-term factors; uncertainty of legal protection of copyholders, heavy war taxes, fall of corn prices, enclosures by agreement and by parlinament which Marxists stressed, partible inheritance system and growth of population in the 18th century which bourgeois historians emphasized. Lastly, just as the fortunes of yeomanry had badly depended on the interference of state power, parliamentary enclosure, so the fate of peasants in Korea will depend on the interference of national power, the Urguay Round. Already considerably declining peasant in Korea are liably to trace the same fate as yeomanry in the 18th century England, if they won't be sided by the protection of national policy.

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