영원일대(동강)의 수자원 조사

한진수 ( Jin Su Han ),김동석 ( Dong Seog Kim ) 대구가톨릭대학교 자연과학연구소 2003 자연과학연구논문집 Vol.1 No.2

동강유역의 포유동물상 및 어류 조사

김대원 ( Dae Won Kim ),김동석 ( Dong Seog Kim ) 대구가톨릭대학교 자연과학연구소 2003 자연과학연구논문집 Vol.1 No.2

서울 서남부지역 노인 인구에서 비만증 유병률과 고지혈증과의 상관성

최경묵,조영직,김경오,김동림,김난희,백세현,안정천,서홍석,오동주,최동섭 대한노인병학회 2000 Annals of geriatric medicine and research Vol.4 No.3

급성 충수염의 천공여부를 예측할 수 있는 판별함수

민석기,이준희,정병욱,오민구,배성한,박동일,안우섭,서정욱 대한대장항문학회 1996 Annals of Coloproctolgy Vol.12 No.1

VCTFK의 반복피로에 의한 소손 패턴의 특성 해석

최충석,송길목,김동우 한국안전학회 2004 한국안전학회지 Vol.19 No.4

In this paper, we analyzed on the characteristics of the stranded wire disconnected by repeated stress. The stranded wires that were used in the experiment are PVC insulated flexible cords(VCTFK: Vinyl Insulated Vinyl Cabtyrc Cord Flat-type) of 0.75mm², 1.25mm², and 2.Omm². They are used to connect the load in low voltage. The stranded wires disconnected by repeated stress were magnified with optical microscope. Using X-ray, the disconnected wire were photo-graphed. we compared mechanical characteristics of the stranded wire between disconnected tendency and allowable current. On the mechanical strength of vinyl cap tire ellipse type cords under bending stress, VCTFK of 1.25mm²was the strongest of them. When it was bent 826.3±7 times, it appeared the disconnected tendency that element wires of VCTFK of 1.25mm²are more about 1.67 times than element wires of VCTFK of 0.75mm². In mechanical strength, VCTFK of 1.25mm² is higher about 1.7 times than VCTFK of 0.75mm². Therefore, we found out that mechanical strength was higher, when the wire had a lot of element wires. In comparison with bending stress, VCTFK of 1.25mm²is the strongest among samples, and it is the most useful in wires of movable type.

기업의 기부·접대비 지출행위에 관한 연구

홍효석,김동훈,박용철 진주산업대학교 1999 산업과학기술연구소보 Vol.- No.6

This study is to analyze the relation factors of corporate contribution and entertainment expenses. We try to seek to find out the motives of corporate contributions and entertainment expense for describing factors. Previous study is reported different result for our study. Then this study reexamines about this more analytical approach. We select 2,062 sample firms during 1991-1996 and result using correlation analysis is as follows. Contribution and entertainment expense shows a significantly positive with firm size that is corporate sales except for 1991. The contribution and entertainment expense has a significant positive relation with cash flow, industry contribution level, pre-period contribution level, advertisement, research and development cost, effective tax rate, retained earnings. In the case of debt ratio, the result shows significantly negative relation. Therefore we assert that the contribution and entertainment expenses are made for earnings management.

연속회분식 생물막 반응기에서 여재 충진율의 영향

김동석,박민정 한국환경과학회 2003 한국환경과학회지 Vol.12 No.7

This study was carried out to get more operational characteristics of the sequencing batch biofilm reactors with media volume/reactor volume ratio of 15 %, 25 % and 35 %. Experiments were conducted to find the effects of the media packing ratio on organic matters and nutrients removal. Three laboratory scale reactors were fed with synthetic wastewater. During studies, the operation mode was fixed. The organic removal efficiency didn't show large difference among three reactor of different packing media ratios. However, from the study results, the optimum packing media ratios for biological nutrient removal was shown as 25%. The denitrifying PAOs could take up and store phosphate using nitrate as electron acceptor.

선재압연 공정에서 압하력 근사해석방법

정동원,이영석 제주대학교 산업기술연구소 2001 尖端技術硏究所論文集 Vol.12 No.1

This paper presents a semi-analytical method for the prediction of roll force in oval-round (or round-oval) pass rolling sequence most commonly employed in present continuous rod (or bar) mills. Introduced was a concept of a weak plane strain deformation taking into account of the deformation characteristics of workpiece (material) in the roll grooves when the equation for the roll force was formulated. Flow stress (deformation resistance) of the workpiece was characterized by Shidas constitutive equation. Hot rod rolling experiment was conducted to examine the proposed semi-analytical method. Result reveals that using the weak plane strain deformation condition was found to be appropriate in solving three-dimensional problems. where it was often necessary to reduce the cost of computation by simplification. For low plain carbon steel, the roll forces predicted were in good agreement with those obtained experimentally with the rolling temperature changed (800 ∼ 1100C).

S. cerevisiae와 A. pullulans를 이용한 중금속 제거에 있어 중금속의 선택도에 관한 연구

김동석,서정호,이종헌,송승구 대구효성가톨릭대학교 응용과학연구소 1997 응용과학연구논문집 Vol.6 No.1

폐수중에 함유한 중금속을 처리하기 위하여 미생물을 이용한 중금속 제거공정의 응용가능성을 알아보고자 하였다. Cd, Cr, Ni, Pb을 사용하여 균류인 S. cerevisiae와 A. pullulans의 각 단일 중금속에 대한 제거 선택도와 혼합 중금속의 제거 선택도를 관찰하였고, Pb에 대한 2가지 미생물의 제거특성을 고찰함으로써 각 제거기작에 대한 기초연구를 하였다. 1) S. cerevisiae와 A. pullulans에 대한 단일 중금속(Cd, Cr, Ni, Pb)의 선택도는 다음과 같다 Pb>Cr>Ni>Cd (S. cerevisiae) Pb>Cr>Cd>Ni (A. pullulans) 2) S. cerevisiae와 A. pullulans에 대한 혼합 중금속(Cd, Cr, Ni, Pb)의 선택도는 다음과 같다. Pb>Cr>Ni>Cd (S. cerevisiae) Pb>Cr>Ni>Cd (A. pullulans) 3) 본 실험에서의 선택 순서는 중금속의 원자반경의 크기에 따라 나타났다. 4) S. cerevisiae의 Pb 제거 특성에 있어 초기 PB의 농도가 증가할수록 단위 미생물당 중금속 제거량은 증가하였으며 평형에 도달하는 시간도 증가하는 것으로 나타나, Pb의 세포내 침투가 발생함을 간접적으로 알 수 있었다. 5) A. pullulans는 Pb의 제거에 있어 S. cerevisiae와 마찬가지로 초기 Pb의 농도가 증가할수록 단위 미생물당 중금속 제거량은 증가하였으나, 평형에 도달하는 시간은 초기 Pb의 농도에 거의 무관하였다. 그러므로 A. pullulans의 Ph 제거기작에서는 Pb의 세포내 침투가 발생하지 않음을 간접적으로 알 수 있었다. 6) 2종류 미생물의 PB에 대한 제거능을 비교해보면 초기 Pb의 농도가 96 mg/l 정도인 경우에 A. pullulans에서는 단위 미생물당 흡착량이 120 mg Pb^2+/g로 나타났으나, S. cerevisiae의 경우에서는 70 mg Pb^2+/g로 나타나, 미생물을 이용한 중금속 제거공정을 실용화하고자 할 경우에는 A. pullulans가 보다 유리할 것으로 판단되었다. Waste heavy metals which have a reputation of detrimental effect on the environment through the food chain are generated from mining, dyestuff, material, electric, and petroleum industries. In this study, the feasibility a heavy metal removal process using microorganisms which is an alternative method to remove and recover heavy metals was examined, in order to treat the heavy metal in waste water. The removal selectivity about single and mixed heavy metals(Cd, Cr, Ni, Pb) using Saccharomyces cerevisiae and Aureobasidium pullulans, and the effect of initial heavy metal concentration on the removal of heavy metal were determined. The order of selectivity were Pb〉Cr〉Ni〉Cd(S. cerevisiae) and Pb〉Cr〉Cd〉Ni(A. pullulans) in single metal solution and Pb〉Cr〉Ni〉Cd(S. cerevisiae and A. pullulans) in mixed metal solution. The order of selectivity was mainly depended on the ionic radius. The amounts of heavy metal removal and the time required to the equilibrium state were increased according to the increase of initial heavy metal concentration in S. cerevisiae, but the time to reach equilibrium state was independent of initial concentration in the case of A. pullulans. These facts show that the penetration of heavy metal into the inner cellular part was occured in S. cerevisiae and it cannot be done in A. pullulans.

형광등용 안정기의 화재원인 판정에 관한 연구

최충석,백동현 한국화재소방학회 2000 한국화재소방학회논문지 Vol.14 No.3

본 연구에서는 옥내 조명으로 널리 사용되고 있는 형광등용 안정기의 화재위험성을 분석하였다. 안정기 권선을 실체현미경으로 분석한 결과 용융흔을 다수 발견할 수 있었으나, 육안으로 원인 판정은 불가하였다. 700℃ 이상에서 열열화(熱劣化)된 안정기 권선은 연신구조(elongation structure)가 없어지고 구리입자의 확대된 형태만 보였다. 단락 권선의 금속현미경 분석에서 경계면을 중심으로 주상조직 및 보이드 성장의 규칙성이 확인된 것으로 보아 전기적인 단락이 층간에 일어났음이 증명되었다. SEM을 이용한 미세구조 분석에서 용융된 부분이 확인되었다. EDX를 이용한 스펙트라 분석에서 Cu의 구성요소인 CuL 및 CuK lines뿐만 아니라 OK line이 고르게 관측되고 있다. 이것은 재결합 과정에서 산소가 반응에 참여했음을 의미한다. In this paper, we analyzed the fire hazard of the ballast for fluorescent lamp used as the indoor lighting. In the result of being analyzed the ballast wire by stereo microscope, many melting points were discovered, it was impossible to judge a cause with the naked eye. In the thermal-deteriorated ballast wire, elongation structure disappeared at above 700℃, and it only showed the enlarged appearance of the copper particle. On the metallurgical microscope of short wire, as it was confirmed the regulation of the columnar structure and the void growth at the center of boundary-face, we found that electrical short-circuit generated. Also, it was confirmed the melted part on the analysis using SEM(scanning electron microscope). Not only CuL and Cuk line that is composition factor of copper but also OK line was observed uniformly on the spectra analysis using EDX(energy dispersive x-ray spectroscopy). It means that oxygen took part in reaction at the recombination process.