• Journal of Soil and Groundwater Environment
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• 제11권6호
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• pp.61-68
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• 2006

Soil washing techniques coupled with high pressure air jet were applied for diesel-contaminated soils sampled by an underground oil reservoir of which the initial total petroleum hydrocarbon (TPH) ($2,828{\pm}206\;mg/kg$) exceeded 5 times of current standard level (500 mg/kg) regulated by the Soil-Environment Conservation Law. Through several tests, we found that the position of impeller has a critical impact for washing efficiencies. The highest washing efficiency was obtained at an oblique angle (30 degree) for the impeller and optimized mixing speed (300 rpm) that could have high shearing forces. Considered economical and feasible aspects, the optimum mixing time was 10 min. Rate constants of TPH removal derived from the first-order equation were not linearly increased as mixing speed increased, indicating that mechanical mixing has some limits to enhance the washing efficiencies. Application of high-pressure air jet in washing process increased the washing efficiency. This increase might be caused by the fact that the surface of micro-air bubbles strongly attached hydrophobic matters of soil particles. As the pressure of air jet increased, the separation efficiencies of TPH-contaminated soil particles increased. In the combined process of high-pressure air jet and mixing by impeller, the optimum mixing speed and air flow-rate were determined to be 60 rpm and $2\;kg/cm^2$, respectively. Consequently, the washing technique coupled with high-pressure air jet could be considered as a feasible application for remediating petroleum-contaminated soils.

• The Journal of Engineering Geology
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• 제31권2호
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• pp.165-178
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• 2021

The influence of Soil-Water Characteristic Curve (SWCC) fitting parameters for an unsaturated natural slope was evaluated through seepage and slope stability analysis as a function of rainfall. Soil samples were collected from the study area in Jirisan National Park and the physical and mechanical characteristics of unsaturated soil layers were measured in laboratory tests. The saturation depth was calculated via seepage analysis by changing fitting parameters α, the parameter related to the Air Entry Value (AEV) and n, the parameter related to the slope of the SWCC in the range of natural conditions. Slope stability analysis using the limit equilibrium method considered the calculated depth of saturation. Results from seepage analysis for various rainfall conditions indicate the saturation depth in the soil layer suddenly increased as the fitting parameter α decreased; the saturation time for the entire soil layer also decreased. Slope stability analysis considering the calculated depth of saturation shows that the slope safety factor rapidly decreased as the fitting parameter α decreased, whereas the variation in slope safety factor was very small when n increased. Hence, fitting parameter α has a large effect on saturation depth during rainfall and therefore on slope stability, whereas slope stability is relatively unaffected by the fitting parameter n.

• Journal of the Korean GEO-environmental Society
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• 제12권12호
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• pp.21-30
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• 2011

The recycled soil that is proceeded from demolition concrete structures was analyzed by the methods of the physical and mechanical tests of soil and TCLP test to use the soil in low landfilling for the construction of an industrial complex. The laboratory test for diffusion of alkali ion in soil mass was analyzed by the methods of XRF and ICP. The fish toxicity test was also conducted to find an environmental influence. The recycled soil through the laboratory test satisfied the engineering property for low landfilling and the criteria of soil contamination. However, the solution which producted by 1:1 ratio of recycled soil and water contained the high pH concentration by alkali ion. The calcium hydroxide solution by CSH cement paste was estimated as the main reason why pH concentration is increased more than 9.0. The high pH concentration in recycled soils causes a toxicity to the livability of fishes. A diffusion area of pH concentration in the ground was analyzed by the Visual Modflow Ver. 2009 program based on geotechnical investigation. The high pH concentration in the recycled soils can be remained as high value due to cement paste in the long term period. Therefore, in the early stage of landfilling work, the mixing with the weathered granite soil is necessary to control the pH concentration.

• Journal of Korean Society of Transportation
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• 제26권3호
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• pp.31-40
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• 2008

There have been a lot of efforts to find more accurate evaluation methods for traffic signal control effectiveness for a long period of time. Nowadays a newly advanced method called HILSS, 'Hardware-in-the-Loop-Simulation System', is used to evaluate the overall traffic control's effectiveness including physical control environments like communication conditions, hardware performance, controller's mechanical operations and so on. In this study, an Online-HILSS model has been developed, which runs on CORSIM(5.0) micro traffic simulation model on-lined to COSMOS. For the verification of the model, three tests are performed as follows; (1) a comparison of TMC's timing plan with the simulated green interval, (2) as a case study, a delay distribution comparison of the online simulation with the CORSIM stand-alone simulation. The result of the first test shows that the model can run the simulation green interval by TMC's timing plan correctly. The result of second test shows that the online simulation of the model brings the same simulation results with the CORSIM offline simulation in case of the same timing plan. These results mean that the online evaluation model could be a reliable tool to measure a real-time signal control effectiveness of a wide area street network with the HILSS method.

• Journal of the Korean Arthroscopy Society
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• 제16권1호
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• pp.1-8
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• 2012

Purpose: To evaluate clinical and radiologic outcomes of transphyseal anterior cruciate ligament (ACL) reconstruction in patients with open physes who were selected with authors' new operative indications. Materials and Methods: We evaluated 15 patients with open physes who underwent a transtibial ACL reconstruction and were followed up for 4~6 years after surgery. Our operative indications involved 1) choronologic age of ${\geq}$ 16 in male and ${\geq}$ 14 in female, 2) open physes of ${\leq}$ 2 mm width, and 3) Risser sign and Tanner stage of ${\geq}$ 3. Tibialis anterior tendon allograft was used in all patients, and endobutton and bioscrew were used for femoral and tibial fixations, respectively. Functional outcomes were evaluated using Lysholm Knee Scoring scale, Tegner activity scale, and International Knee Documentation Committee (IKDC) 2000 subjective score. Physical examinations to evaluate stability involved Lachman and pivot shift tests. For radiographic results, we evaluated side to side differences of anterior displacement in stress views. In addition, with use of scannograms taken at last follow-up, we examined side to side differences of femorotibial angles, anatomical and mechanical lateral distal femoral angles, mechanical medial proximal tibial angles and leg lengths. Results: The mean Lysholm Knee score was 51(40-61) points preoperatively and 97(94-100) points at last follow up. The mean Tegner activity score was 2.6 points preoperatively and 7.1 points at last follow up. The mean IKDC score was 32.6 points preoperatively and 88.3 points at last follow up. The mean anterior displacement of the tibia was improved from 6.7(${\pm}1.0$) mm to 1.9(${\pm}0.9$) mm. There were no leg length discrepancies over 5 mm and no statistically significant differences in all the radiographic variables representing growth disturbance. Conclusion: This study suggests that patients with open physes who selected by authors' new indication would safely undergo transphyseal ACL reconstruction with successful outcomes.

• Korean journal of applied entomology
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• 제12권3호
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• pp.93-107
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• 1973

Garlic (Allium sativum L.) is an important vegetable crop for the Korean people and has long been cultivated extensively in Korea. More recently it has gained importance as a source of certain pharmaceuticals. This additional use has also contributed to the increasing demand for Korean garlic. Garlic has been propagated vegetatively for a long time without control measures against virus diseases. As a result it is presumed that most of the garlic varieties in Korea may have degenerated. The production of virus-free plants offers the most feasible way to control the virus diseases of garlic. However, little is known about garlic viruses both domestically and in foreign countries. More basic information regarding garlic viruses is needed before a sound approach to the control of these diseases can be developed. Currently garlic mosaic disease is most prevalent in plantings throughout Korea and is considered to be the most important disease of garlic in Korea. Because of this importance, studies were initiated to isolate and characterize the garlic mosaic virus. Symptom expression in test plants, physical properties, purification, serological reaction and morphological characteristics of the garlic mosaic virus were determined. Results of these studies are summarized as follows. 1. Surveys made throughout the important garlic growing areas in Korea during 1970-1972 revealed that most of the garlic plants were heavily infected with mosaic disease. 2. A strain of garlic mosaic virus was obtained from infected garlic leaves and transmitted mechanically to Chenopodium amaranticolor by single lesion isolation technique. 3. The symptom expression of this garlic mosaic virus isolate was examined on 26 species of test plants. Among these, Chenopodium amaranticolor, C. quince, C. album and C. koreanse expressed chlorotic local lesions on inoculated leaves 11-12 days after mechanical inoculation with infective sap. The remaining 22 species showed no symptoms and no virus was recovered from them whet back-inoculated to C. amaranticolor. 4. Among the four species of Chtnopodium mentioned above, C. amaranticolor and C. quinoa appear to be the most suitable local lesion test plants for garlic mosaic virus. 5. Cloves and top·sets originating from mosaic infected garlic plants were $100\%$ infected with the same virus. Consequently the garlic mosaic virus is successively transmitted through infected cloves and top-sets. 6. Garlic mosaic virus was mechanically transmitted to C, amaranticolor when inoculations were made with infective sap of cloves and top-sets. 7. Physical properties of the garlic mosaic virus as determined by inoculation onto C. amaranticolor were as follows. Thermal inactivation point: $65-70^{\circ}C$, Dilution end poiut: $10^-2-10^-3$, Aging in vitro: 2 days. 8. Electron microscopic examination of the garlic mosaic virus revealed long rod shaped particles measuring 1200-1250mu. 9. Garlic mosaic virus was purified from leaf materials of C. amaranticolor by using two cycles of differential centrifugation followed by Sephadex gel filtration. 10. Garlic mosaic virus was successfully detected from infected garlic cloves and top-sets by a serological microprecipitin test. 11 Serological tests of 150 garlic cloves and 30 top-sets collected randomly from seperated plants throughout five different garlic growing regions in Korea revealed $100\%$ infection with garlic mosaic virus. Accordingly it is concluded that most of the garlic cloves and top-sets now being used for propagation in Korea are carriers of the garlic mosaic virus. 12. Serological studies revealed that the garlic mosaic virus is not related with potato viruses X, Y, S and M. 13. Because of the difficulty in securing mosaic virus-free garlic plants, direct inoculation with isolated virus to the garlic plants was not accomplished. Results of the present study, however, indicate that the virus isolate used here is the causal virus of the garlic mosaic disease in Korea.

• Tunnel and Underground Space
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• 제22권4호
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• pp.266-275
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• 2012

In this study, a method is devised to implement a supercritical $CO_2$ ($scCO_2$) injection environment on a laboratory scale and to investigate the effects of $scCO_2$ on the properties of rock specimens. Specimens of shale and sandstone normally constituting the cap rock and reservoir rock, respectively, were kept in a laboratory reactor chamber with $scCO_2$ for two weeks. From this stage, a chemical reaction between rock surface and the $scCO_2$ was induced. The effect of saline water was also investigated by comparing three conditions ($scCO_2$-rock, $scCO_2-H_2O$-rock and $scCO_2$-brine(1M)-rock). Finally, we checked the changes in the properties before and after the reaction by destructive and nondestructive testing procedures. The swelling of shale was a main concern in this case. The experimental results suggested that $scCO_2$ has a greater effect on the swelling of the shale than pure water and brine. It was also observed that the largest swelling displacement of shale occurred after a reaction with the $H_2O-scCO_2$ solution. The results of a series of the destructive and nondestructive tests indicate that although each of the property changes of the rock differed depending on the reaction conditions, the $H_2O-scCO_2$ solution had the greatest effect. In this study, shale was highly sensitive to the reaction conditions. These results provide fundamental information pertaining to the stability of $CO_2$ storage sites due to physical and chemical reactions between the rocks in these sites and $scCO_2$.

• Korean Journal of Ecology and Environment
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• 제40권1호
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• pp.130-142
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• 2007

This study was to examine impacts of turbid water on fish community in the downstream of Yongdam Dam during the period from June to October 2006. For the research, we selected six sampling sites in the field: two sites were controls with no influences of turbid water from the dam and other remaining four sites were the stations for an assessment of potential turbid effects. We evaluated integrative health conditions throughout applications of various models such as necropsy-based fish health assessment model (FHA), Index of Biological Integrity (IBI) using fish assemblages, and Qualitative Habitat Evaluation Index (QHEI). Laboratory tests on fish exposure under 400 NTU were performed to find out impact of turbid water using scanning electron microscope (SEM). Results showed that fine solid particles were clogging in the gill in the treatments, while particles were not found in the control. This results indicate that when inorganic turbidity increases abruptedly, fish may have a mechanical abrasion or respiratory blocking. The stream health condition, based on the IBI values, ranged between 38 and 48 (average: 42), indicating a "excellent" or "good" condition after the criteria of US EPA (1993). In the mean time, physical habitat condition, based on the QHEI, ranged 97 to 187 (average 154), indicating a "suboptimal condition". These biological outcomes were compared with chemical dataset: IBI values were more correlated (r=0.526, p<0.05, n=18) with QHEI rather than chemical water quality, based on turbidity (r=0.260, p>0.05, n=18). Analysis of the FHA showed that the individual health indicated "excellent condition", while QHEI showed no habitat disturbances (especially bottom substrate and embeddeness), food-web, and spawning place. Consequently, we concluded that the ecological health in downstream of Yongdam Dam was not impacted by the turbid water.

• Journal of the Korean Wood Science and Technology
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• 제17권1호
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• pp.3-11
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• 1989

This study was carried out to investigate the physical and mechanical properties. durability of adhesive bond and paint film for the basic data which were required to determine the suitability as a raw material for furniture the laminated veneer lumber (LVL) with pitch pine (Pinus rigida Mill). The results obtained were as follows; 1) The proper pressing time for making the LVL was over 45 second per milimeter of LVL thickness. 2) The bending strength of the LVL was lower than that of the solid wood but the compressive strength of the LVL was similar to that of the solid wood. The strength increased with the decrease of veneer thickness. 3) The impact bending absorbed energy of the LVL was 0 to 0.3 kg.m/$cm^2$ in the direction of parallel to the grain. The energy of the LVL was lower than that of the solid wood (0.68 kg.m/$cm^2$). 4) In warm water soaking and cold-dry tests, delamination of adhered layers surface crack, swelling, and color change were not found when the hot pressing time was over 45 second per milimeter of LVL thickness. As a result of soak under vacuum test shrinkage in the direction of parallel to the grain was about -1.0 percent and. was about 3.0 percent in the direction of the perpendicular to the grain. 6) The film cacks on the LVL's surface after the wet and cold-dry test were not found at all. 7) In the use of the LVL for interior decoration it was considered that the surface of the LVL be overlaid crossly with fancy veneers of birch and paulownia, etc. This cross overlayirg methods have resulted in few cracks on the fancy veneer.

• Journal of the Korean Geotechnical Society
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• 제35권8호
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• pp.43-56
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• 2019

This research has been conducted to suggest an estimation equation of compression index to be practically applied to the southeastern areas by finding out physical and mechanical characteristics of 229 points on the southeastern coast areas (Busan area: 78 points, Gimhae area: 103 points, Geoje area: 18 points, Changwon area: 30 points) through indoor tests and analyzing its relation to the compression index. From the results, we could not only find out correlation between natural water content, liquid limit and initial void ratio versus compression index for soft ground on each of the southeastern coast areas, but also an integrated correlation equation of the southeastern coast areas. In addition, we have performed a comparative analysis of the existing estimated equation of compression index and that found in this paper. As a result, the existing estimated equation suggested by foreign researchers has shown considerable error to be applied to the soft ground on the southeastern coast areas in Korea. The estimated equation of compression index with the water content out of the existing estimated equations has shown minimum 10.8% to maximum 48.1% of error rate, minimum 13.4% to maximum 288.5% of error rate with liquid limit or minimum 9.4% to maximum 211.4% of error rate with initial void ratio. On the other hand, error rates calculated with the estimated equations of compression index from this research have shown minimum 10.5% to maximum 13.4% with water content, minimum 11.6% to maximum 21.3 with liquid limit or minimum 7.1% to maximum 11.7% with initial void ratio, for better results than those with existing estimated equations. In addition, relation between compression index and expansion index has shown Cs = (1/5 ~ 1/12)Cc similar to the existing relation of Cs = (1/5 ~ 1/10)Cc.