• Journal of Korea Spatial Information System Society
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• v.11 no.3
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• pp.1-8
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• 2009

In this study the concepts on the elongation, compactness and equivalent ellipse of catchment plan-forms are applied to the real basins considering their theoretical frameworks. The catchment plan-forms and corresponding equivalent ellipses, obtained from GIS, are inspected on downstream directions. As a result the catchment plan-forms seem to be the population of the basin shapes which come from the random interaction between two conjectures on Hack's law being controversial recently. The ratio of the maximum and minimum inertia moments of the catchment plan-form Ri is more sensitive to evaluate the elongation of the basin shapes than the ratio of the main channel length and diameter of circle which has the same area as the catchment plan-form E. The catchment plan-forms compactness measures show distinct aspects according to their different definitions. These results are caused by the difficulties to quantification of the shapes and the composite consideration with more than two compactness measures and the fractal analysis are therefore required to recover them.

• Fire Science and Engineering
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• v.32 no.1
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• pp.24-32
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• 2018

There are two kinds of method on hydraulic calculation of fire sprinkler system design. The one is using the computational program and the other is designer calculate system for oneself. In case of using the computational program, putting the input data in, the program calculate the friction loss, water flow, total height and so forth. If program user or designer doesn't know the basic idea and procedure of hydraulic calculation. Then, the outputs are different from each other. This paper suggests the hydraulic calculation procedure in design area as follow. Equivalent lengths of tees on the branch are selected base on the same pipe diameter which the tees are established, although the diameter of tee outlet is different. Even though there is a different friction loss of head from the other head, the pressure from the hydraulic end is bigger than a head loss, discharge flow is calculated by pressure from the hydraulic end.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.358-363
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• 1995

A study on passive cooling systems for concrete containment of advanced pressurized water reactors has been performed. The proposed passive containment cooling system (PCCS) consist of (1) condenser units located inside containment, (2) a steam condensing pool outside containment at higher elevation, and (3) downcommer/riser piping systems which provide coolant flow paths. During an accident causing high containment pressure and temperature, the steam/air mixture in containment is condensed on the outer surface of condenser tubes transferring the heat to coolant flowing inside tubes. The coolant transfers the heat to the steam condensing pool via natural circulation due to density difference. This PCCS has the following characteristic: (1) applicable to concrete containment system, (2) no limitation in plant capacity expansion, (3) efficient steam condensing mechanism (dropwise or film condensation at the surface of condenser tube), and (4) utilization of a fully passive mechanism. A preliminary conceptual design work has been done based on steady-state assumptions to determine important design parameter including the elevation of components and required heat transfer area of the condenser tube. Assuming a decay power level of 2%, the required heat transfer area for 1,000MWe plant is assessed to be about 2,000 ㎡ (equivalent to 1,600 of 10 m-long, 4-cm-OD tubes) with the relative elevation difference of 38 m between the condenser and steam condensing pool and the riser diameter of 0.62 m.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.1
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• pp.241-254
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• 1999

The purpose of this study was to investigate whether a radiometric analysis of radicular cysts and periapical granulomas is useful in the differential diagnosis. In this experiment, twenty-nine periapical radiographs of the radicular cyst and those periapical granuloma were used. The periapical radiography was taken by intraoral paralleling device. The X-ray film was digitized and digitally filtered to reduce film-grain noise. We estimated density difference of the inner/outer area, roundness or circularity, bone profile or scan line of the margin and cumulative percentage frequency curve of radicular cyst & periapical granuloma. The obtained results were as follows; 1. The differences in density between ROIs of inner and outer area of radicular cysts were smaller than those of periapical granulomas. 2. The equivalent circular diameter was over 6.3mm, there was significant difference between periapical cyst and periapical granuloma. 3. In differential diagnosis of radicular cyst and periapical granuloma using bone profile. sensitivity. specificity and accuracy were considerably high(0.83. 0.86. 0.86) respectively. 4. Cumulative percentage frequency curve of the radicular cyst was closer to the pseudo-pixel value of 50 than average curve, whereas periapical granuloma was closer to that of 0. Hence we conclude that digital radiometric features might be useful in the differential diagnosis between radicular cyst and periapical granuloma.

• Journal of the Korean institute of surface engineering
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• v.34 no.1
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• pp.33-38
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• 2001

10cm-diameter Si(100)∥$1.3\mu\textrm{m}$-X$1.3_2$X$1.3\mu\textrm{m}$-$SiO_2$∥Si(100) afers were prepared using a fast linear annealing (FLA) equipment. 1.3$\mu\textrm{m}$-thick $SiO_2$ films were grown by dry oxidation process. After cleaning and premating the wafers in a class 100 clean room, they were heat treated using with the FLA and conventional electric furnace. Bonded area and bond strength of wafer pairs were measured using a infrared (IR) camera and razor blade crack opening method, respectively. It was confinmed that the bonded area by FLA was around 99% and the bond strength value reached 2172mJ/$\m^2$, which is equivalent to theoritical bond strength. Our result implies that thick $SiO_2$ SOI may be prepared more easily by using $SiO_2$$SiO_2$ bonding interfaces then those of Si/$SiO_2$'s.

• Journal of Forest and Environmental Science
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• v.39 no.3
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• pp.119-127
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• 2023

In this study, quantitative models were applied to case parks to estimate the carbon reduction by trees, which was compared and analyzed at the tree and park levels. At the tree level, quantitative models of carbon storage and uptake differed by up to 7.9 times, even for the same species and size. At the park level, the carbon reduction from quantitative models varied by up to 3.7 times for the same park. In other words, carbon reduction by quantitative models exhibited considerable variation at the tree and park levels. These differences are likely due to the use of different growth environment coefficients and annual diameter at breast height growth rates and the overestimation of carbon reduction due to the substitution of the same genus and group model for each tree species. Extending the annual carbon uptake per unit area of the case park to the total park area of Chuncheon a carbon uptake ranging from a minimum of 370.4 t/yr and a maximum of 929.3 t/yr, and the difference can reach up to 558.9 t/yr. This is equivalent to the carbon emissions from the annual household electricity consumption of approximately 2,430 people. These results suggest that the indiscriminate application of quantitative models to estimate carbon reduction in urban trees can lead to significant errors and deviations in estimating carbon storage and uptake in urban greenspaces. The findings of this study can serve as a basis for estimating carbon reduction in urban greening research, projects, and policies.

• Journal of Korean Society for Atmospheric Environment
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• v.5 no.1
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• pp.68-78
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• 1989

The heavy metal of suspended particulates with human health has long been studied in environmental interest concerned. This study was intended to identify harmful heavy metals of the ambient air borne dusts which were related with the respirable sizes in the aerodynamics. Two sampling sites were selected comparatively; one was in the Shinchon area, which is the commercial district with heavy traffic and the other site was in the Bulgwang area which is residential area. The supended particulates were sampled by high volume air sample with 6 cascade impactor stages. The heavy metals in terms of As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V and Zn were determined by stomic absorption spectrometry or inductively coupled plasma emission spectrometry. The samples weretaken bimothly for seven consecutive days from May 1987 to March 1988. The annual average concentration of the respirable suspended dust of which diameter is less than 10$\mum$ was 152.59 $\mug/m^3$ of the Shinchon air samples; the respirable dust was equivalent to approximately 85% of the total suspended particulates. The annual average concentration of the respirable suspended dust of the Bulgwang air samples was 112.56 $\mug/m^3$; that was approximately 86% of the total suspended particulates. The concentration of heavy metals was investigated in relation to the particle size. The concentration of Cr, Fe, Mn and V were tended to be much more in the coarse particles than in the fine particles. Cd and Pb in the fine particles were more than in the coarse particles. In the partial correlation coefficients; in the Shinchon area, high correlations among Fe, Se and Mn were determined; it is assumed that those sources would be originated from coal, gasolineand diesel. In Bulgwang area, would be high correlation among Fe, Se, Hg and Mn considered to be originated from coal, Bunker-C and heavy oil as well. From the above results, the hazardous heavy merals in air should be measured and controlled in originally their sources.

• Korean Journal of Optics and Photonics
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• v.11 no.1
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• pp.58-64
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• 2000

Assuming that the performance of holographic storage media is ideal, we estimate the area storage density of disk-type holographic memories, when the method of either angle multiplexing, or rotational multiplexing, or both are used. The area storage density is strongly dependent on the f numbers (ratio of focal length to diameter) of both the Fourier transform lens in the signal arm, denoted by $F/#_2$, and the angle range over which the reference beam is incident (or, the equivalent f number corresponding to the angle range denoted by $F/#_1$). The area storage density is largely independent of the pixel pitch of the spatial light modulator when the Fourier plane holograms are recorded, while it is sensitive to the pixel pitch when the image plane holograms are recorded. In general, to obtain high area storage density, the Fourier or at least near Fourier plane holograms rather than the image plane holograms should be recorded. In addition, when the thickness of the recording materials are less than approximately $500\mu\extrm{m}$, rotational multiplexing gives higher area storage densities than angle multiplexing does. To increase the storage density further, however, it is desirable to use both of the two multiplexing methods in combination.nation.

• Journal of Biosystems Engineering
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• v.40 no.3
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• pp.212-223
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• 2015

Purpose: Physical properties of Detarium microcarpum seeds were investigated as a function of moisture content to explore the possibility of developing bulk handling and processing equipment. Methods: Seed size, surface area, and 1,000-seed weight were determined by measuring the three principal axes, measuring area on a graph paper, and counting and weighing seeds. Particle and bulk densities were determined using liquid displacement and weight in a measuring cylinder, respectively. Porosity was computed from particle and bulk densities. Roundness and sphericity were measured using shadowgraphs. Angle of repose and static and kinetic coefficients of friction were determined using the vertical cylindrical pipe method, an inclined plane, and a kinetic coefficient of friction apparatus. Results: In the moisture range of 8.2%-28.5% (db), the major, intermediate, and the minor axes increased from 2.95 to 3.21 cm, 1.85 to 2.61 cm, and 0.40 to 1.21 cm, respectively. Surface area, 1,000-seed weight, particle density, porosity, and angle of repose increased from 354.62 to $433.19cm^2$, 3.184 to 3.737 kg, 1060 to $1316kg/m^3$, and 30.0% to 53.1%, respectively, whereas bulk density decreased from 647.6 to $617.2kg/m^3$. Angle of repose increased from $13.9^{\circ}$ to $28.4^{\circ}$. Static and kinetic coefficients of friction varied between 0.096 and 0.638 on different structural surfaces. Conclusions: Arithmetic mean, geometric mean, and equivalent sphere effective diameters determined at the same moisture level were significantly different from each other, with the arithmetic mean diameter being greatest. Surface area, 1,000-seed weight, particle density, porosity, and angle of repose all increased linearly with moisture content. Bulk density decreased linearly with moisture content. The coefficients of friction had linear relationships with moisture content. The highest values of static and kinetic coefficients of friction were observed on galvanized steel and hessian fabric, respectively, whereas the lowest values were observed on fiberglass.

• Economic and Environmental Geology
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• v.11 no.3
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• pp.99-108
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• 1978

The Gum-Ho river basin is one of the densely populated area having more than 35% of the total population and it was also well irrigated since earlier days in the Nackdong river basin. Most of the easily developed source of surface water are fully utilized, and at this moment the basin is at the stage that no more :surface water can be made available under the present rapid development of economic condition. Since surface water supplies from the basin have become more difficult to obtain, the ground water resources must be thoroughly investigated and utilized greatly hereafter. In economic ground of the basin what part could ground water play? In what quantities and, for what uses could it be put? The answer to these questions can be relatively simple;the ground water resources in the basin can be put at almost any desired use and almost anywhere in the basin The area of the basin is at about $2088km^2$ in the middle part of Nackdong river basin and it is located along the Seoul-Pusan express highway. The mean annual rainfall is about 974.7mm, most of which falls from June to September during the monsoon. Accumulated is appeared approximately after every 8 year's accumlated dry period with the duration of 5 years. The water bearing formation in the basin include unconsolidated alluvial deposits in Age of Quaternary, saprolite derived from weathered crystalline rocks, Gyongsang sedimentary formations of the period from late Jurassic to Cretaceouse, and igneouse rocks ranging of the Age from Mesozoic to Cenozoic. The most productive ground water reservoir in the basin is calcareous shale and sandstones of Gyongsang system, which occupies about 66% of the total area. The results of aquifer test on Gyongsang sedimentary formation show that average pumping capacity of a well drilled into the formation with drilling diameter and average depth of $8{\frac{1}{2}}$ inch and 136m is $738m^3/day$ and also average specific capacity of those well is estimated $77.8m^3/D/M$. Total amount of the ground water reserved in the basin is approximately estimated at 37 billion metric tons, being equivalent 18 years total precipitations, among which 7 billion metric tons of portable ground water can be easily utilized in depth of 200 meters.