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등간격으로 배열된 마이크로폰을 이용한 관내 유량측정 방법
김용범,김양한 한국소음진동공학회 2001 소음 진동 Vol.11 No.1
Proposed in this paper is a method of measurement of the flow rate in a pipe. The sound waves which are propagated within a pipe are characterized by that the wavenumber in the axial direction is changed according to the flow rate, and these characteristics are used in the present method of measurement of the flow rate. The amount of change in wavenumber of sound waves according to the flow rate can be obtained from the relationship among acoustic pressure signals within a pipe, which are measured by using a microphone array. The flow rate can be obtained by using the amount of change in wavenumber of sound waves and the relational equation of the flow rate. With respect to errors that can occur during the measurement of the flow rate, the types of errors and the method of correction of those errors are presented. This method of measurement of the flow rate has application limitation conditions due to the sensor interval, assumption of sound waves as plane waves, etc. The numerical simulation and experiments for measuring the flow rate of air in a pipe are performed in order to verify the applicability of this method of measurement of the flow rate. The experimental results are shown to be similar to those of the numerical simulation. And the flow rate measured is shown to be consistent with the actual value within 5% error bound.
키토산에 대한 Itaconic acid의 graft 공중합과 그 특성
한상문,윤충수,김용범 서울산업대학교 산업대학원 1999 大學院論文集 Vol.6 No.-
Chitosan was prepared from chitin which was abstracted from wasted crab shell. Then itaconic acid was graft-copolymerized onto chitosan using ceric ammonium nitrate(CAN) as a reaction initiator. To investigate the optimal grafting conditions, the influences of several factors on the grafting were studied, i.e., the concentrations of CAN and itaconic acid, the reaction temperature and time. And to find out its flocculation ability, the flocculation test was carried out with a metal plating factory waste water. The state of the graft-copolymer was identified through IR spectra checking. The optimal grafting conditions and flocculation results were shown to be: concentration of ceric ammonium nitrate is ??, reaction temperature is 40℃ and reaction time is 4hrs with 0.25M of the monomer(itaconic acid). Through flocculation tests using chitosan, grafted chitosan(CsIa) and cation, CODcr, metal ions removal rates were measured. The order of superiority is CsIa>Cs>Cation.
Pulse Polarography에 依한 微量金屬元素의 定量에 關하여
金容範 忠州大學校 1981 한국교통대학교 논문집 Vol.14 No.2
The author studied the advantages of pulse polarogram comparing with the classical DC & AC polarogram. The reaults obtained by pulse polarography are as follow; Here a separated-compartment polarographic cell was used to allow the use of calomel reference electrode, the potential of which is not disturbed by the falls of the mercury drops; the effectiveness of this separated-compartment was found to give a stable and well-defined potential. 1) Sensitivity: It was possible to measure concentrations of Cd²?? as low as 10-?? M. 2) Resolution power: When two elements were reduced at potentials very close one from the other, it was not anymore possible to distinguish the peaks related respectively to each of them the resolution power has been estimated to 40mV in the case of the reduction of In³?? and Cd²?? 3) Interference factor F; Interference factor F refers to the ratio of the concentrations of elements A and B over which the element A cannot be detected because of the interference with the peak of element B. The results obtained here are; <수식입력불가> in the indifferent electrolyte 10-¹M KCI solution.
Mineral trioxide aggregate가 인간치수세포에서 유전자 발현에 미치는 영향
김용범,손원준,이우철,금기연,백승호,배광식 大韓齒科保存學會 2010 Restorative Dentistry & Endodontics Vol.35 No.3
이 연구에서는 mineral trioxide aggregate (MTA)를 in vitro로 인간치수세포에 적용하였을 때 유전자들의 변화를 조사하였다. 실험군은 MTA를 teflon tube (직경 10 mm 길이 2 mm)에 담아 4시간 경화시킨 후HDPCs에 적용하였고, 대조군은 빈 tub만을 적용하였다. 6, 24, 72시간 후 total RNA를 추출하여 microarray를 이용하여 분석하여, 2배 이상 또는 절반 이하의 변화를 보이는 유전자 중 선택적으로 역전사 중합효소 연쇄반응(reverse transcriptase polymerase chain reaction)을 사용하여 발현을 확인하였다. 24,546개의 유전자 중에서 109개의 유전자가 2배 이상 up-regulation되었으며(예. FOSB, THBS1, BHLHB2, EDN1, IL11, FN1, COL10A1, TUFT1) 69개의 유전자가 50%이하로 down-regulation되었다(예. SMAD6, DCN). MTA는 bio-inert한 재료라기 보다는 치수세포에 다양한 경로로 영향을 주는 재료로 사료된다. 특히 치수세포의 분화와 증식에 관여하는 유전자의 변화에 영향을 주며 석회화 과정에 관여하는 유전자의 변화에 직접적인 영향을 주리라 사료된다. This study investigated the changes in gene expression when mineral trioxide aggregate (MTA) was applied in vitro to human dental pulp cells (HDPCs). MTA in a teflon tube (diameter 10 mm, height 2mm) was applied to HDPCs. Empty tube-applied HDPCs were used as negative control. For microarray analysis, total RNA was extracted at 6, 24, and 72 hrs after MTA application. The results were confirmed selectively by performing reverse transcriptase polymerase chain reaction for genes that showed changes of more than two-fold or less than half. Of the 24,546 genes, 109 genes were up-regulated greater than twofold (e.g., FOSB, THBS1, BHLHB2, EDN1, IL11, FN1, COL10A1, and TUFT1) and 69 genes were downregulated below 50% (e.g., SMAD6 and DCN). These results suggest that MTA, rather than being a bioinert material, may have potential to affect the proliferation and differentiation of pulp cells in various ways.