肝細胞의 Cell Cycle과 Circadian Rhythm에 對하여

嚴正燮,李隆昌 최신의학사 1974 最新醫學 Vol.17 No.8

In order to estimate the circadian variation of cell cycle of liver cell 3H-thymidine was introduced into one day postnatal male chicks of Shaver species and autoradiography was carried out. The chickss were divided into two experimental groups; AM and PM groups. At the beginning of every hour, starting from 5:03 AM for 25 hours, 3 healthy chicks were carefully selected and injected with given doses of (3)^H-thymidine to be used as the AM group. PM chickss were treated in the same manner starting from 2:00 PM. AM chicks were sacrificed at 6:00 AM and PM chicks at 3:03 PM next day. The livers of these animals were autoradiographed. These results were analyzed and compared with previous studies. The results were summarized as follows: 1. The duration of TG was 398 hours in AM chicks and 530 hours in PM chicks. 2. The durarion of S phase was 17.5 hours in AM chicks and 10.6 hours in PM chicks. 3. The duration of G2 phase was 2.5 hours in AM chicks and 2.8 hours in PM chicks. 4. The duration of M phase was 1.0 hour in AM chicks and 1.2 hours in PM chicks. 5. The duration of Gl phase was 377 hours in AM chicks and 516 hours in PM chicks. Labelling indices of AM and PM chicks were 4.4% and 2.0% respectively. Difference between the generation times of AM and PM chicks was significant showing the influence of circadian rhythm. Difference between the durations of S phases of AM and PM chicks was significant. Durations of G, phases of AM and PM groups revealed a remarkable difference.

Airborne video as a remote sensor for environmental monitoring of linear infrastructure: a case study and review

엄정섭 대한공간정보학회 2004 Spatial Information Research Vol.12 No.4

At present, environmental monitoring of linear infrastructure is based mainly on field sampling. The 'integrated mapping' approach has received only limited attention from field scientists. The increased environmental regulation of corridor targets has required remote sensing research to develop a sensor or technique for targets ranging from 15 m to 100 m in swath width. In an attempt to identify the optimal remote sensing system for linear targets, an overview is provided of the application requirements and the technology currently available. The relative limitation of traditional remote sensing systems in such a linear application is briefly discussed. It is noted that airborne video could provide, in a cost-effective manner, information required for a very narrow and long strip target utilising the narrow view angle and dynamic stereo coverage. The value of this paper is warranted in proposing a new concept of video infrastructure monitoring as a future research direction in the recognition of sensor characteristics and limitations.

하천 수질 감시에서 비디오 원격탐사와 이화학적 샘플링 조사의 비교평가

엄정섭 경북대학교 사회과학대학 지리학과 2006 地理學論究 Vol.- No.25

현재 하천 수질 감시는 전적으로 현지 조사에 의거한 이화학적 수질 측정망에 의존하고 있다. 전통적인 현장 샘플링은 조사자 개인의 주관성, 조사지점 선정과정에서 일관성 부족 등으로 인해 특정오염원에 기인한 하천수질의 광역적인 변화 패턴을 파악하는 데 상당한 한계를 가지고 있다. 이와 같은 현지조사 기법 자체가 가지고 있는 한계는 현재의 단일한 기법에 의존하고 방식으로서는 해결될 수 없으며 다양한 관련 기술을 동시에 적용하는 접근이 필요하다. 하천과 같이 선형의 특성을 가진 공간 객체의 원격감시에 항공비디오가 최적의 특성을 가지고 있다는 기존의 각종 연구결과에 의거하여 하천 수질감시에서 항공비디오와 현지조사와의 비교 평가를 시도하고자 본 연구가 출발하였다. 두 기법에 대해 정보의 광역성, 현지의 정황에 대한 구체성, 고객의 요구사항을 수용할 수 있을 정도의 정보 적합성 등 실무적인 차원에서 비교평가가 이루어졌다. 비디오 샘플링 기법은 다양한 샘플지점에서 나타나는 하천 색조의 변화추세를 가시적으로 파악할 수 있었으며 전통적인 현장 샘플링 방법으로는 추적하는 데 상당한 한계가 있는 특정오염원에 기인한 하천수질의 광역적인 변화패턴을 파악하는 데 상당한 가능성을 보여주었다. 하지만 특정 지점에서 시료를 채취하는 현지 샘플링조사는 장거리에 걸친 하천의 수질감시를 위해서는 상당한 한계를 노출하였다. 이와 같이 영구적으로 보전된 영상기록은 오염 물질의 이동확산 등 수질환경의 광역적인 변화 추이에 대한 시각적인 정보를 제공하고 있어 현장샘플링과 동시에 사용할 경우 하천수질감시에 있어 상당히 유용한 도구가 될 수 있음을 보여주었다. At present monitoring for river water quality is based mainly on field sampling. Field sampling survey for river water quality was subject to various inherent limitations, such as personal subjectivity and error in identification of the ground condition. Many inventorying and monitoring problems are not solved entirely by any one approach: no single data-acquisition methodology can satisfy all of the monitoring needs. Based on the postulated advantages of video for corridor monitoring, a comparison between airborne video survey and field sampling approach has been specifically proposed with focus on river water quality monitoring. An exhaustive and realistic comparison of the two techniques was conducted, based on video data and field survey data. Both techniques have been investigated for a variety of aspects: synoptic information, ground detail and information adequacy for customer requirement. The video imagery was able to isolate the area-wide water quality with reliable spatial precision. Although field survey has already gained worldwide recognition by environmental scientists as a typical method of river water quality monitoring, this approach did not provide a level of information that is either scientifically reliable or economically feasible in terms of river water quality management. The observations obtained from this project have implications for the suitability of the video sampling for water quality monitoring in general and other levels of monitoring for river water could be adjusted, based on the understanding of the inherent capability of video sampling shown in this project.

원형관속을 유동하는 점탄성 유체의 입구 영역 열전달 특성에 관한 연구

엄정섭,황태성,유상신 대한기계학회 1989 대한기계학회논문집 Vol.13 No.5

본 연구에서는 해석적으로 열적 입구 길이를 규명하는데 필요한 와류 열확산 계수를 실험 결과를 이용하여 결정하고, 시험관 입구의 형상 변화가 열전달 특성에 미치는 영향을 실험적으로 결정하며, 열적 입구 길이 영역에서 국소 열전달 계수를 표시할 수 있는 실험식을 제시하고, 유체의 전단율에 따른 점성 계수의 실험 결과와 점탄성 유체의 특성시간을 이용한 새로운 무차원 수인 Weissenberg수를 결정하여 퇴화 현상을 분석하고저 한다. The heat transfer characteristics of the drag reducing polymer solutions are investigated experimentally in the thermal entrance region of circular tube flows. Fluids used in experiments are the aqueous solutions of high molecular polymer, polyacrylamide Separan AP-273 and the range of polymer concentrations is from 20 to 1000 wppm. Two stainless steel tubes with inside diameter 8.5mm(L/D=712) and 10.3mm(L/D=1160) are used for the heat transfer flow loops. The flow loop is set up to measure friction factors and heat transfer coefficients of test sections in two different modes; the recirculating flow system and once-through flow system. The test tubes are heated directly by electricity to apply the constant heat flux boundary conditions to the wall. Three different types of adaptors are used to observe the effects of the upstream flow conditions of the heat transfer test sections. The viscosity and characteristic relaxation time of the test fluids circulating in the flow system are measured by the capillary tube viscometer and falling ball viscometer at regular time intervals. The installed adaptors exhibit slight effect on the entrance heat transfer of Newtonian fluid. However, no noticeable effects are observed for the entrance heat transfer of the drag reducing fluids. The order of magnitude of the thermal entrance lengths of the drag reducing fluids which follow the minimum friction asymptote is much longer than that of Newtonian fluids in turbulent flows. A new dimensionless parameter, the viscoelastic Graetz number, is defined and all the experimental data are recasted in terms of the viscoelastic Graetz number. The local Nusselt number of the viscoelastic fluids is represented as a function of flow behavior index n and the viscoelastic Graetz number. As degradation continues the viscosity and the characteristic relaxation time of the testing fluids decrease. Weissenberg number defined by the relaxation time and D/V appears to be a proper dimensionless parameter in describing degradation effects on heat transfer of the viscoelastic fluids.

점탄성유체의 저항 및 열전달 감소현상과 퇴화의 영향에 관한 연구

엄정섭,전찬열,유상신,Eum, C.S.,Jeon, C.Y.,Yoo, S.S. 대한설비공학회 1990 설비공학 논문집 Vol.2 No.1

The drag and heat transfer reduction phenomena and degradation effects of drag reducing polymer solutions which are known as the viscoelastic fluids are investigated experimentally for the turbulent circular tube flows. Two stainless steel tubes are used for the experimental flow loops. Aqueous solutions of Polyacrylamide Separan AP-273 with concentrations from 300 to 1000 wppm are used as working fluids. Flow loops are set up to measure the friction factors and heat transfer coefficients of test tubes in the once-through system and the recirculating flow system. Test tubes are heated by power supply directly to apply constant heat flux boundary conditions on the wall. Capillary tube viscometer and falling ball viscometer are used to measure the viscous characteristics of fluids and the characteristic relaxation time of a fluid is determined by the Powell-Eyring model. The order of magnidude of the thermal entrance length of a drag reducing polymer solution is close to the order of magnitude of the laminar entrance length of Newtonian fluids. Dimensionless heat transfer coefficients of the viscoelastic non-Newtonian fluids may be represented as a function of flow behavior index n and newly defined viscoelastic Graetz number. As degradation continues viscosity and the characteristic relaxation time of the testing fluids decrease and heat transfer coefficients increase. The characteristic relaxation time is used to define the Weissenberg number and variations of friction factors and heat transfer coefficients due to degradation are presented in terms of the Weissenberg number.

원형관 속을 유동하는 점탄성 유체의 입구영역 열전달 특성에 관한 연구

엄정섭,황태성,유상신 대한기계학회 1989 대한기계학회 춘추학술대회 Vol.- No.-

송유관선로의 식생복원 감시를 위한 비디오선형지도화 및 patch dynamics 분석 ( Video Strip Mapping ( VSM ) and Patch Dynamics Analysis for Revegetation Monitoring of a Pipeline Route )

엄정섭 대한지리학회 1998 대한지리학회지 Vol.33 No.3

Tracheal Wall Thickening Is Associated with the Granulation Tissue Formation Around Silicone Stents in Patients with Post-Tuberculosis Tracheal Stenosis

엄정섭,김호중,전경만,엄상원,고원중,서지영,정만표,권오정 연세대학교의과대학 2013 Yonsei medical journal Vol.54 No.4

Purpose: Tracheal restenosis due to excessive granulation tissue around a silicone stent requires repeated bronchoscopic interventions in patients with post-tuberculosis tracheal stenosis (PTTS). The current study was conducted to identify the risk factors for granulation tissue formation after silicone stenting in PTTS patients. Materials and Methods: A retrospective study was conducted between January 1998 and December 2010. Forty-two PTTS patients with silicone stenting were selected. Clinical and radiological variables were retrospectively collected and analyzed. Results: Tracheal restenosis due to granulation tissue formation were found in 20 patients (47.6%), and repeated bronchoscopic interventions were conducted. In multivariate analysis, tracheal wall thickness, measured on axial computed tomography scan, was independently associated with granulation tissue formation after silicone stenting. Furthermore, the degree of tracheal wall thickness was well correlated with the degree of granulation tissue formation. Conclusion: Tracheal wall thickening was associated with granulation tissue formation around silicone stents in patients with post-tuberculosis tracheal stenosis.

지리교육 보조도구로서의 지리정보과학

엄정섭 慶北大學校 社會科學大學 地理學科 2002 地理學論究 Vol.- No.22

지방자치단체의인터넷GIS 사이트 평가기준설정및 적용

엄정섭 국토연구원 2003 국토연구 Vol.37 No.-

The constant increasing use of the internet GIS in local government authorities implies that it is necessary to have in place a reliable mechanism for quality assurance of the sites. However, existing Web site evaluation models are primarily based on attributes relating to the non-spatial contents, and therefore are not adequate in evaluating a variety of Internet GIS sites in a systematic manner. This paper is intended to determine criteria for evaluating internet GIS sites of local government authorities. After carefully reviewing the previous literature of Government website evaluation, three criteria were identified: (1) contents (2) design (3) spatial navigation. An empirical study has been conducted to validate each of the three categories using two samples of internet GIS sites from Korea (Daegu) and USA (San Diego). A site diagnosis by the criteria allowed us to identify strength and weakness of the two sample sites. For example, overall operation strategies in the San Diego site were closely linked to the UIS (Urban Information System) while the Daegu site was not user-friendly to track required local government specific information since it is offered by initiative of the firm outsourcing the Web site. The organizations operating internet GIS sites may use the proposed criteria to evaluate their Web sites against those of others and to possibly make them more competitive. Future research will need to refine and expand specifically tailored to each of the different Web site categories.