• Journal of the korean society of oceanography
• /
• 제32권3호
• /
• pp.93-102
• /
• 1997

Coastal circulations during the (surface condition of an) idealized cold-air outbreak are numerically investigated with two-dimensional, non-hydrostatic model in which a constant bottom-slope exists. The atmospheric forcing during a cold-air outbreak is incorporated as the surface cooling and the wind stress. When the offshore angle of the wind-stress vector, defined as the angle measured from the alongshore axis, is smaller than 45 degrees, a strong downwelling circulation develops near the coast. A sharp density front, which separates the vertically homogeneous region from the offshore stratified region, is formed near the coast and propagates offshore with time. Onshore side of the density front, small-scale circulation cells which are aligned in the direction perpendicular to the bottom begin to develop as the near-coast homogeneous region broadens. The surface cooling enhances greatly the development of the surface mixed layer by convective motions due to hydrostatic instability. The convective motions reach far below the hydrostatically unstable layer which is attached to the surface. The small-scale circulation cells are appreciably modified by the convetion cell and the density front develops far offshore compared to the case of no surface cooling. As to the effect of the bottom slope, the offshore distance of the density front increases (decreases) as the bottom slope decreases (increases), which results from the fact that the onshore volume-transport (Ekman transport) of the low-density upper seawater remains almost constant when the wind-stress is maintained constant. It is shown that the bottom slope is an essential factor for the formation of both the density front and the alongshore current when the surface cooling is the only forcing.

• Ecology and Resilient Infrastructure
• /
• 제6권4호
• /
• pp.258-266
• /
• 2019

This study was conducted to apply natural river technologies to levees and examine the results. The new eco-friendly bio-polymer was applied, a combination of eco-friendly biopolymers and soil, to levee slope to enhance durability and eco-friendliness and to establish reinforcement measures against unstable levees due to overtopping. A semi-prototype levee of 1 m in height, 3 m in width, with a 1:2 slope and 5 m length, was constructed at the Andong River Experiment Center. The bio-soil mixed with the biopolymer and the soil at an appropriate ratio was treated with a 5 cm thickness on the surface of levee to perform the stability evaluation according to overtopping. Using the pixel-based analysis technique using the image analysis program, the breached area of levee slope was calculated over time. As a result, the time for complete decay occurs more than 12 times than that of ordinary soil levee. Therefore, when the new substance is applied to the surface of levee, the decay delay effect appears to be high.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• 제17권1호
• /
• pp.91-109
• /
• 2014

This study was conducted to obtain the basic research about Siberian roe deer (Capreolus pygargus), and to establish a conservation area into Seoraksan(Mt.) National Park, South Korea. We recorded Siberian roe deer field signs (bedding sites, feeding areas, feces and tracks etc), and habitat variables such as nearest distance to the watercourse, trails, slope, aspect, forest type and land cover etc. from Jan. 2006 to Dec. 2007 in Seoraksan(Mt.) National Park. According to the research of habitat characteristics of Siberian roe deer inhabited in Seoraksan(Mt.) National Park preferred mixed forest consisted of aged forest and middle-aged forest on the gentle slope which was close to hydrosphere in the middle elevation area of altitude of 400~600m above sea level in Seoraksan(Mt.) National Park. The results indicated that Siberian roe deer appeared to prefer south slope or north slope during the snow season and west or east slope during the non-snow season. The area of most suitable habitat for Siberian roe deer in Seoraksan(Mt.) National Park was $128.5km^2$ (32% of the total area) followed by $244.3km^2$ buffer area (62.2% of the total area), and $22.9km^2$ unsuitable habitat area (5.8% of the total area), which means environmentally unsuitable habitat for Siberian roe deer was rare in Seoraksan(Mt.) National Park. Thus, the area classified as major area in Seoraksan(Mt.) National Park appeared to be most important for the protection of Siberian roe deer.

• Journal of Environmental Science International
• /
• 제16권8호
• /
• pp.907-912
• /
• 2007

Ion exchange resin was used to remove silica ion at ultralow concentration. The effects of temperature, type of ion exchange resin and single/mixed-resin systems on removal efficiency were estimated. As temperature increased, the slope of concentration profile became stiff, and the equilibrium concentration was higher. In the single resin system, the removal of silica was continued up to 400 min, but the silica concentration was recovered to initial concentration after 400 min due to the effect of dissolved $CO_2$. In the mixed-resin system it took about 600 min to reach equilibrium. Because of faster cation exchange reaction than anion exchange reaction, the effect of $CO_2$ could be removed. Based on the experimental results carried out in the mixed-resin system, the selectivity coefficients of silica ion for each ion exchange resin were calculated at some specific temperatures. The temperature dependency of the selectivity coefficient was expressed by the equation of Kraus-Raridon type.

• Journal of Korean Society of Water and Wastewater
• /
• 제24권2호
• /
• pp.219-230
• /
• 2010

Computer simulation has been widely used to design and optimize the operation of wastewater treatment plants since 1980. For secondary clarifiers, the simulation has been a tool to optimize the performance by providing dimensions for flocculation well. However, there has been no attempt to find the optimized geometrical parameters in circular secondary clarifier using simulation tools. In this study, three SVIs (Sludge Volume Indexes), two well types (feed and flocculation wells), 8 SWDs (Side Water Depths) and 9 bottom slopes were variables for simulation. Diurnal inflow and associated MLSS (Mixed Liquor Suspended Solid) concentrations were used for input loadings. When flocculation well was installed, 48% less concentration at lowest ESS (Effluent Suspended Solid) concentrations was produced and the diurnal ESS concentration range had been reduced by 52%. From these results, flocculation well must be installed to produce lower and stable ESS from circular secondary clarifiers. Under same loading conditions with $300m{\ell}$/g of SVI, The lowest ESS was produced when SWD was 4.5m with 4% of bottom slope. Therefore, SWD and bottom slope must not be deeper than 4.5m and must be near 4%, respectively, in circular clarifier with flocculation well to produce the lowest ESS concentration.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• 제15권10호
• /
• pp.2093-2099
• /
• 2011

Speech signal and car noise signal such as muffler noise are segregated from the one which has both signals mixed using statistical method. To classify speech signal from the other in segregated signals, FFT coefficients were obtained for all segments of a signal where each segment consists of 128 elements of a signal. For several coefficients of FFT corresponding to the low frequencies of a signal, autocovariances are calculated between coefficients of same order of all segments of a signal. Then they were averaged over autocovariances. Linear equation was eatablished for the those autocovariances using the linear regression method for each siganl. The coefficient of the slope of the line gives reference to compare and decide what the speech signal is. It is what this paper proposes. The results show it is very useful.

• Journal of Korean Society for Atmospheric Environment
• /
• 제17권5호
• /
• pp.385-393
• /
• 2001

We have developed a Differential Absortion LIDAR (DIAL) method for the measurement of lower tropospheric ozone concentration. We used two laser beams from quadrupled Nd:YAG (266 nm) for the resonance wavelength and dye lasers (299.5 nm) for non -resonance wavelength. Aerosol extinction coefficients in the lower troposphere was computed by both Klett and Slope methods. To correct the SIN (Signal -Induced Noise) effect caused by photo detector, we subtracted a new-fitted baseline on the background part of a LIDAR signal, after the subtraction of the DC level. This is because SIN can be treated as an exponentially decaying tail. Using theme results, ozone profiles were obtained approximately 2km at daytime and 3km at nighttime. We compared the results derided by the Slope method with those measured by UV spectrometer. The computed results are in mostly good agreement with experimental results. In the measurement of the vertical layer, we observed the variation of the ozone profiles around the top mixed layer.

• Journal of the Korean Institute of Rural Architecture
• /
• 제8권1호
• /
• pp.111-120
• /
• 2006

Our ancestor has accumulated inimitable a building system from experience. and they finally invented Gu-dul that heat the stone as a hitting system. The purpose of this study is to investigate and to write down the on Excavation & Restoration of Traditional Gu-dul in Young-dong. It was found that Gu-dul was the most suited for natural condition. That is wind, direction, earth level. As the results of analyzing the built- technque of traditional Gu- dul : 1) The Gu-dul type is lined, scattered, and mixed. 2) The hight of bank is 25-30cm, 3) The depth of Gaejari is 30-45cm, and The slope of that is gentle. 4) The slope of Gorae(a floor hitter) is 5 - 8%. (from the middle to the edge and from the lower part to the upper part) Therefore, For the practical application of future houses, it will be needed to develop the reasonable hitting system, and suggest to set up Gu-dul for our health and saving energy.

• Bulletin of the Korean Chemical Society
• /
• 제26권10호
• /
• pp.1565-1568
• /
• 2005

A surface renewable pH electrode was prepared by utilizing composite electrode technique. Iridium oxide micro-fine particles was prepared by hydrolysis of $(NH_4)_2IrCl_6$ at elevated temperature. The iridium oxide particles were mixed with well-dispersed carbon black and then filtered. The mixture was suspended in DMF containing PVC as a binder. The mixture was precipitated rapidly by adding large amount of water. The precipitate was ground and pressure-molded to iridium oxide composite electrode material. The electrode showed linear response between pH 1-13 with 50 to 60 mV/pH slope. The electrode maintained the pH response without appreciable slope drift for 170 days if stored in deionized water. The electrode surface can be renewed reproducibly by simple grinding process whenever contaminated or deactivated.

• Journal of The Geomorphological Association of Korea
• /
• 제19권1호
• /
• pp.69-81
• /
• 2012

This study analyzed the relationship between the geomorphic factor and changes in forest types of the Chungnam coastal area using ASTER DEM and multi-temporal satellite imagery. The results showed that in case coniferous forests vary by altitudinal segments, reduction rate continuously increased up to 500m, but dropped upon exceeding 550 meters. Next, the variation rate of mixed forests by altitudinal segments decreased from less than 50m. However, the variation rate of mixed forests increased from more than 50m to 700m, but dropped upon exceeding 700m. Lastly, the variation rate of deciduous forests according to altitudinal segments increased at all altitudes. A sharp increase was found in segments of more than 550 meters. With regard to the changes in the distribution area of forest types according to slope aspects, coniferous forests showed a reduction in all slope aspects. The reduction rate was especially higher in northern, northwestern, western and northeastern aspects. Mixed forests manifested a high growth rate in northwestern, northern and western aspects, but slightly decreased in eastern and southeastern aspects. In addition, deciduous forests increased in all slope aspects, but the growth rate was especially high in eastern, southeastern, northeastern and southern aspects.