• Korean Journal of Environmental Agriculture
• /
• v.25 no.4
• /
• pp.297-305
• /
• 2006

The field lysimeter experiment were undertaken to investigate the runoff and erosion loss of four pesticides from sloped land by rainfall and to assess the influence of pesticide properties, environmental factors and agricultural practices on them. The pesticide losses from soybean planted field and bare field were measured using field lysimeters. Pesticide losses from a series of lysimeter plots of sloped land by rainfall ranged $0.1{\sim}0.6%$ for alachlor, $1.1{\sim}4.5%$ for ethalfluralin, $8{\sim}31%$ for pendimethalin and 0.03% for ethoprophos, which were $1/3{\sim}2.5$ times to them in the simulated rainfall study. The erosion loss rates of pesticides from soybean-plots were $21{\sim}75%$ lower than the ones from bare soil plot. The effect of slope conditions was not great for runoff loss, but for erosion loss increased to maximum $4{\sim}12$ times by sloping degree and slope length. The peak runoff concentration in soybean-plots and bale soil plots were $3{\sim}278{\mu}gL^{-1}\;and\;6{\sim}450{\mu}gL^{-1}$ for alachlor, $1.1{\sim}11.4{\mu}gL^{-1}\;and\;0.9{\sim}16{\mu}gL^{-1}$ for ethalfluralin, $7{\sim}42{\mu}gL^{-1}\;and\;6{\sim}66{\mu}gL^{-1}$ for pendimethalin, and $2{\sim}53{\mu}gL^{-1}\;and\;0.1{\sim}113{\mu}gL^{-1}$ for ethoprophos, respectively, on nine different slope degree and slope length plots. Therefore, the differences of the peak runoff concentration between bare soil plots and soybean-plots were not great.

• Journal of radiological science and technology
• /
• v.35 no.2
• /
• pp.83-92
• /
• 2012

In anteroposterior projection for cervical vertebra, it is general that the incidence angle of X-ray is $15^{\circ}$ to $20^{\circ}$ degrees to head in order to prevent overlap of mandible and occipital bone and to observe array of cervical interbody and shapes of joints. However, the angle is appropriate for foreigners that was determined by foreign literature review long ago, and there have been few researches of incidence angle for Koreans' body type. The purpose of in this study are to identify the incidence angle appropriate for Koreans and to present methodology. In order to measure the incidence angle, 1,044 patients who visited S Hospital located in Seosan were selected and measured of average length of cervical vertebra, OID, axis angle, and FID. The incidence angle was calculated from the applied formula by measuring average values per age groups and sex (see Formula 1 and 2). The average length of cervical vertebra was 6cm: the length was increased from teenagers to twenties but was decreased since thirties. The difference between males and females was around 1cm (p<.01). The OID was almost the same regardless of age groups and sex. As for axis angle, the slope was increased in teenagers and twenties, but was decreased since thirties. The difference between males and females was around 2 degrees (p<.01). The FID measurements were almost the same regardless of age groups and sex, and when the incidence angle was measured from these values, the teenagers were $15.9^{\circ}$, the twenties were $16.9^{\circ}$, the thirties were $16.6^{\circ}$, the forties were $16.2^{\circ}$, the fifties were $15.9^{\circ}$, and the sixties were $14.5^{\circ}$, indicating that the angle was increased from teenagers to the twenties but decreased since the thirties. While the angles of males and females were measured to be the same in the teenagers, the angle was different between males and females by $2^{\circ}$. When the incidence angle statistically analyzed with measurement of average length of cervical vertebra, OID, axis angle, and FID, all of them were shown to have correlations with the incidence angle (p<.01). Conclusively, it was shown that the incidence angle was measured differently from average length of cervical vertebra, OID, FID, and axis slope, as well as from age and sex. Therefore, it can be suggested that the anteroposterior radiation test for cervical vertebra should be conducted by different incidence angles based on age and sex. The data of this study may be used as reference in determining the incidence angle of cervical vertebra tests for the future.

• Journal of The Korean Astronomical Society
• /
• v.35 no.3
• /
• pp.111-121
• /
• 2002

We have measured the correlation functions of the optically selected clusters of galaxies in the Abell and the APM catalogs, and of the X-ray clusters in the X-ray-Brightest Abell-type Clusters of galaxies (XBACs) catalog and the Brightest Clusters Sample (BCS). The same analysis method and the same method of characterizing the resulting correlation functions are applied to all observational samples. We have found that the amplitude of the correlation function of the APM clusters is much higher than what has been previously claimed, in particular for richer subsamples. The correlation length of the APM clusters with the richness R $\ge$ 70 (as defined by the APM team) is found to be $r_0 = 25.4_{-3.0}^{+3.1}\;h^{-1}$ Mpc. The amplitude of correlation function is about 2.4 times higher than that of Croft et al. (1997). The correlation lengths of the Abell clusters with the richness class RC $\ge$ 0 and 1 are measured to be $r_0 = 17.4_{-1.1}^{+1.2}$ and $21.0_{-2.8}^{+2.8}\;h^{-1}$ Mpc, respectively, which is consistent with our results for the APM sample at the similar level of richness. The richness dependence of cluster correlations is found to be $r_0= 0.40d_c + 3.2$ where $d_c$ is the mean intercluster separation. This is identical in slope with the Bahcall & West (1992)'s estimate, but is inconsistent with the weak dependence of Croft et al. (1997). The X-ray bright Abell clusters in the XBACs catalog and the X-ray selected clusters in the BCS catalog show strong clustering. The correlation length of the XBACs clusters with $L_x {\ge}0.65{\times} 10^{44}\;h^{-2}erg\;s^{-1}$ is $30.3_{-6.5}^{+8.2}\;h^{-1}$ Mpc, and that of the BCS clusters with $L_x {\ge}0.70{\times} 10^{44}\;h^{-2}erg\;s^{-1}$ is $30.2_{-8.9}^{+9.8}\;h^{-1}$ Mpc. The clustering strength of the X-ray clusters is much weaker than what is expected from the optical clusters.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.12
• /
• pp.5-12
• /
• 2008

The reinforced earth wall, which is able to improve the strength of soil highly, is required in case of supporting high surcharge load such as high speed rail way, high embankment road, and massive reinforced earth wall in a mountainous area. And also, it is continuously required that the method is able to minimize the amount of excavated soil on account of environmental issue, boundary of land, etc., on excavation site. However, because the required length of reinforcement should be $60{\sim}80%$ of the height of reinforced earth wall for general reinforced earth wall, in fact the reinforced earth wall is hardly applied on the site of cut slope. In this paper we studied the design and construction cases of hybrid reinforcement retaining wall system combined with steel strips and soil nails, connecting the reinforced earth wall reinforcements to the slope stability reinforcements (soil nails) to ensure sufficient resistance by means of reducing the length of reinforcements of reinforced earth wall. And the feasibility of hybrid reinforcement retaining wall system, suggested by real data measured on site, is also discussed.

• Computers and Concrete
• /
• v.34 no.1
• /
• pp.15-31
• /
• 2024

This study explores the failure mechanisms of 'I' shaped non-persistent cracks under uniaxial loads through a combination of experimental tests and numerical simulations. Concrete specimens measuring 200 mm×200 mm×50 mm were manufactured, featuring 'I' shaped non-persistent joints. The number of these joints varied from one to three, with angles set at 0, 30, 60, and 90 degrees. Twelve configurations, differing in the placement of pre-existing joints, were considered, where larger joints measured 80 mm in length and smaller cracks persisted for 20 mm with a 1 mm crack opening. Numerical models were developed for the 12 specimens, and loading in Y-axis direction was 0.05 mm/min, considering a concrete tensile strength of 5 MPa. Results reveal that crack starting was primarily influenced by the slope of joint that lacks persistence in relation to the loading direction and the number of joints. The compressive strength of the samples exhibited variations based on joint layout and failure mode. The study reveals a correlation between the failure behavior of joints and the number of induced tensile fracture, which increased with higher joint angles. Specimen strength increased with decreasing joint angles and numbers. The strength and failure processes exhibited similarities in both laboratory testing and numerical modeling methods.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.03a
• /
• pp.228-233
• /
• 2004

The spray and acoustic characteristics by the self-oscillation of a swirl coaxial injector were experimentally studied. The self-oscillation of a swirl coaxial injector is defined as pressure and flowrate oscillations by a time-delayed feedback between liquid and gas phase and has strong influences on atomization and mixing processes. Hence the occurrence and effect of the self-oscillation are measured using shadow photography technique, acoustic test and PDPA. The occurrence of self-oscillation largely depends on the injection conditions, such as pressure drop of liquid phase and relative momentum ratio. From the experimental results, self-oscillation occurs when the momentum of gas phase is enough large and the smaller the pressure drop of liquid phase is, the better self-oscillation occurs at the same momentum ratio. The self-oscillation is also affected by injector geometries, increasing the recess length results in the expansion of self-oscillation region and the increase of sound pressure level. The self-oscillation of a swirl coaxial injector accompanies a high intensity scream and this scream may provide harmful disturbances to combustion processes. Self-oscillation leads to strong changes in the drop size distribution and smoothly varies the slope of radial SMD distribution.

• Animal cells and systems
• /
• v.2 no.4
• /
• pp.477-481
• /
• 1998

Previous studies have postulated that isometric animals exert similar locomotory capacity (speed, distance) because the amount of energy available for the motion would be the same regardless of body mass (m). To test propriety of this theory, we examined body shape and take-off potential of two frog species, Rana nigromaculata (powerful jumpers) and Bombina orientalis (slow hoppers). Morphological measurements included thigh muscle mass (indicative of total muscle force), hindlimb length (L, determining acceleration distance), and interilial width (shaping take-off motion). To gauge locomotory capacity, take-off speed (v) and take-off angle ($\theta$) were measured from video analyses, and jump distance (R) and take-off Power ($P_{t}$ ) were calculated from equations $R=V^{2}sin2\theta/g$ and ($P_{t}$＝$㎷^{3}/2L$(where g is the gravitational constant). Scaling exponents of morphometric variables for both species were 0.96-1.11 for thigh muscle mass, 0.28-0.29 for hindlimb length, and 0.30-0.36 for interilial width. Scaling exponents of locomotory performance for the two species were -0.01-0.14 for take-off speed, 0.24-0.31 for jump distance, and 0.66-0.84 for take-off power. The results demonstrate that the frogs of this study showed isometric body shape within species, but that take-off response changed allometrically with body mass, indicating that these data did not fully support the previous proposition. An exception was found in take-off speed of B. orientalis, in which the speed changed little with body mass (slope＝-0.01). These findings suggest that the energy availability approach did not properly explain the apparent allometric relations of the take-off response in these animals and that an alternative model such as a power production approach may be worth addressing.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.1B
• /
• pp.63-70
• /
• 2011

To install the side weirs in inlet of washland construction, it is necessary to calculate more accurately the discharges over side weir. In this study, the hydraulic experiments were performed in broad crested side weirs that installed trapezoidal channel and that considered more applicable to the actual river. Upstream Froude number in the main channel and weir height, length, width and slope of main channel were considerd for estimation of discharge coefficient of broad crested side weir. Experimental results show that the discharge coefficient of broad crested side weir depend on, and. New estimated equation for the discharge coefficient are suggested through the multiple regression analysis and its applicability is confirmed by comparing estimated and measured discharges over side weirs.

• The Journal of the Acoustical Society of Korea
• /
• v.22 no.4E
• /
• pp.167-175
• /
• 2003

Shear wave velocity was measured and grain size analysis was conducted on two core samples obtained in unconsolidated marine sediments of the western continental margin, the East Sea. A pulse transmission technique based on the Hamilton frame was used to measure shear wave velocity. Duomorph ceramic bender transducer-receiver elements were used to generate and detect shear waves in sediment samples. Time delay was calculated by changing the sample length from the transducer-receiver element. Time delay is 43.18 μs and shear wave velocity (22.49 m/s) is calculated from the slope of regression line. Shear wave velocities of station 1 and 2 range from 8.9 to 19.0 m/s and from 8.8 to 22 mis, respectively. Shear wave velocities with depth in both cores are qualitatively in agreement with the compared model〔1〕, although the absolute value is different. The sediment type of two core samples is mud (mean grain size, 8-9Φ). Shear wave velocity generally increases with sediment depth, which is suggesting normally consolidated sediments. The complicated variation of velocity anisotropy with depth at station 2 is probably responsible for sediment disturbance by possible gas effect.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2002.05b
• /
• pp.1334-1339
• /
• 2002

The objective of this study is to help practicing engineers easily use the Clark model which is used for estimating the magnitude of design flood for small stream. A representative unit hydrograph was derived on the basis of the past rainfall-runoff data and unit hydrographs, and the storage coefficient of Clark model was estimated by using hydrograph recession analysis. Since the storage coefficient(K) is a dominating factor among the parameters of Clark method, a mulitple regression formula, which has the drainage area, main channel length and slope as parameters, is propsed to estimate K value of a basin where measured data are missing. The result of regression analysis showed that there is a correlation between a storage coefficient(K) and aforemetioned three parameters in homogenious basins. A regression formular for K was derived using these correlations in a basin of Han River, Nakdong River, Young River, Kum River and Sumjin River