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하상경사가 변화는 실험실 데이터를 이용한 Chiu의 유속공식과 Manning 의 유속공식과의 비교분석
추태호(Choo, Tai-Ho),옥치율(Ok, Chi-Youl),이승관(Lee, Seoung-Kwan),제성진(Je, Sung-Jin) 한국산학기술학회 2007 한국산학기술학회 학술대회 Vol.- No.-
현재까지 수리학 분야에서 가장 많이 회자되고 인용된 공식이 있다면 아마도 1890년에 발표한 Manning의 유속 공식이라고 해도 과언은 아닐 것이다. 그만큼 그 쓰임새가 많았을 뿐만 아니라 사용의 편리성과 정확도에서도 매우 우수하였기 때문일 것이다. 그러나, 아무리 우수한 공식이라도 약점이 있듯이, Manning의 유속공식 역시 조도계수n을 추정하는데 많은 어려움이 있는 것도 주지의 사실이다. 이러한 어려움을 극복하기 위하여, 본 연구에서는 확률통계에서 사용되는 엔트로피 개념을 이용한 3차원 유속분포식인 Chiu의 유속공식을 사용하였다. 그러나 지금까지 실증적으로 Chiu의 유속공식과 Manning의 유속공식을 비교분석하였던 논문은 Chiu와 Choo의 논문에서 일부 언급된 것 외 논문에서는 찾아볼 수 없는 것이 현실이다. 따라서 본 연구에서는 하상경사를 임의로 변경 가능한 실험수로를 선택하여 정밀법에 의한 유속측정을 우선 실시하였다. 같은 지점의 같은 단면에서 하상경사(Ө)가 0.000935부터 0.025794까지 28번의 경사변화를 주고 각 경사마다 유량을 측정하여 28개의 유량측정 데이터를, Chiu의 유속공식과 Manning의 유속공식에 각각 적용하여, Chiu의 M과 Manning의 n사이의 관계뿐만 아니라, 하상경사변화에 따른 관련인자들을 함께 분석하였으며, 실측된 평균유속과도 함께 분석하였다.
영구치 치수 기질세포를 이용한 연골 분화 및 분화 시기에 따른 형태학적 변화
정주령,김하나,박열,김민정,오영주,신수정,최윤정,김경호 大韓齒科保存學會 2012 Restorative Dentistry & Endodontics Vol.37 No.1
Objectives: The aim was to confirm the stem cell-like properties of the dental pulp stromal cells and to evaluate the morphologic changes during in vitro chondrogenesis. Materials and Methods: Stromal cells were outgrown from the dental pulp tissue of the premolars. Surface markers were investigated and cell proliferation rate was compared to other mesenchymal stem cells. Multipotency of the pulp cells was confirmed by inducing osteogenesis, adipogenesis and chondrogenesis. The morphologic changes in the chondrogenic pellet during the 21 day of induction were evaluated under light microscope and transmission electron microscope. TUNEL assay was used to evaluate apoptosis within the chondrogenic pellets. Results: Pulp cells were CD90, 105 positive and CD31, 34 negative. They showed similar proliferation rate to other stem cells. Pulp cells differentiated to osteogenic, adipogenic and chondrogenic tissues. During chondrogenesis, 3-dimensional pellet was created with multi-layers, hypertrophic chondrocyte-like cells and cartilage-like extracellular matrix. However, cell morphology became irregular and apoptotic cells were increased after 7 day of chondrogenic induction. Conclusions: Pulp cells indicated mesenchymal stem cell-like characteristics. During the in vitro chondrogenesis, cellular activity was superior during the earlier phase (within 7 day) of differentiation.
K+-Dibenzo-18-Crown-6 착물의 안정도에 미치는 용매효과
張珠晥,申甲鐵 慶尙大學校 1980 論文集 Vol.19 No.1
The stability constants of the complexation of KSCN with dibenzo-18-Crown-6 was determined conductometrically at constant ionic strength of∼10-3M and at 10°, 25°, 40° and 60℃ in aprotic solvents which were poor anion solvating solvent; N, N'-dimethylformamide N.N'-dimethylacetamide and dimethylsufoxide. The magnitude of the stability constants were obtained by the order of DMF>DMA>DMSO. This order was dependent on the solvent property as function donocity. From the stability constants, the thermodynamic parameters-enthalpy change and entropy change for the complexation were evaluated.
電子빔勵起 KrF레이저의 出力特性에 대한 시뮤레이숀 解析
李柱熙,崔富淵 慶熙大學校 1985 論文集 Vol.14 No.-
By developing a comprehensive computer simulation code for e-beam excited KrF lasers, we studied mainly the effect of output performance dependence on excitation rate excited by an intense electron beam. Especially for short pulse (<50 ns) and high excitation rate pumping (>2Mw/㎤), and under realizable conditions, it is found to calculated with an intrinsic laser effieiency as a function of excitation rate. The results were compared with some experimental results, and a fairly good agreement was obtained. At an excitation rate of 7 Mw/㎤, and at a total gas pressure of 2 atm, an intrinsic efficiency of up to 10.5% is found to be attainable. We have also calculated the KrF^* production efficiency and the laser extraction efficiency, and explained the output performance in terms of excitation rate.
문추연,김동일,김수생 동아대학교 생산기술연구소 2000 生産技術硏究所硏究論文集 Vol.5 No.2
Recently in Korea and developed countries, nitrogen and phophorus removal are the main target to improve effluent qualities, in order to protect discharge basins from eutrofication by N and P. Introduction of an advanced treatment function to existing wastewater treatment systems, which can be removed nitrogen and phophorus as well as BOD, COD and SS, have been required to protect water resources from domestic and industrial wastewaters. For the improvement of effluent quality through nitrogen(N) and phophorus (P) removal, this study conducted to investigate and analyse of the municlpal sewage treatment process such as VIP(Virginia Initiative Plant) process on cost effectiveness operating and improvement of effluent quality. Based on the results of the experiments, The average removal efficiencies of organic matter were BOD 87.4 ~ 91.8%, COD 77.7 ~ 81.3%. At influent concentration of T_-N 41.8mg/l, NH_4-N 36.2 mg/l, T_-P 3.14mg/l and PO_4-P 1.6 mg/l, nutrient removal efficiencies were NH_4-N 95.9%, T_-N 67.8%, PO_4-P 69.9%, and T_-P 70.7%.