• Journal of Korea Water Resources Association
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• v.52 no.2
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• pp.133-139
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• 2019

In this study, the degree of scouring according to the bed material according to the flow rate and the relationship between the flow velocity and the bed scouring were investigated in order to examine the operability of the revetment and embankment. The materials used in the experiment were sand and loess as materials used in the embankment. We measured the scouring of the material according to the change of the flow velocity by using the indoor high flow velocity experiment device and verified the flow rate. In this way, The purpose of this study was to compare and analyze changes in material before and after scouring, and compare basal scouring evaluation by bed material with high flow velocity. In case of sand, the cohesive force is very weak, so more than 40% of the material is lost even at less than 1.0 m/s. In the case of loess, less than 6% of the bed material is lost at more than 2 m/s. The reason why the material was lost was that the cohesion was so strong that the material was dried after the compaction and cracked. As a result, the material was lost from the part where the dry crack occurred. In this study, the composition and loss of bed materials were evaluated.

• Korean Journal of Heritage: History & Science
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• v.46 no.3
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• pp.48-67
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• 2013

This study was focused on the recognition of historical values and the establishment of conservation schemes for a Silla stone monument in Bongpyeong-ri, Uljin by combining the humanistic investigation of inscription reinterpretation and the scientific conservational diagnosis of deterioration. According to the investigation of inscription, a total of 13 letters were reconsidered compared to the preceding researches. Thus, the meaning and interpretation of previous inscription was partially changed. This monument is composed of gneissose leucogranite and the most suitable site as provenance of the stone would be the Jukbyeon seashore (2.1km). The site shows similar color, size and composition of minerals, gneissose structure and magnetic susceptibility as the Bongpyeong stone monument. This monument developed a structural crack (crack index 0.4) and a microcrack (crack index 2.0) along the gneissose structure. The horizontal strength is weaker than the vertical strength. Therefore, the cracks should be reinforced and treated. However, consolidating is not urgently needed because the total weathering grade by ultrasonic velocity shows the stage of moderate weathering(3,403m/s, 0.32). Also, the major problems of chemical deterioration are blackening (85.2%) with soil, iron oxide,rubbing mark, and salt crystals (17.3%) from the sea. Therefore, the contaminants and the salt crystals should be removed using pressure spray and pulp paper, while the application of poultice should be examined through clinical tests.

• Journal of Mushroom
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• v.17 no.3
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• pp.126-131
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• 2019

This study sought to identify the optimum substrate composition for the stable bottle cultivation of Sparassis latifolia. The main substrate was fermented larch sawdust. Six nutrient sources were mixed at a maximum volume ratio of 20%. The fresh weight of fruit body was the highest at 128.5 g for GMSL69033 and 126.6 g for 'Neoul' in the treatments of beet pulp and corn flour in a volume ratio of 15:5. In addition, the total cultivation period was 94 days, which was shorter than that required for other treatments. The selected substrate characteristics were pH 4.7, C:N (carbon to nitrogen) ratio of 106:4, moisture content of 70%, and air filling porosity of 38%. We plan to develop new income items through research on mycelial incubation and fruit body growth conditions.

• Journal of Environmental Science International
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• v.28 no.4
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• pp.413-422
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• 2019

The objective of this study was to estimate the trends of air quality in the study area by analyzing monthly and seasonal concentration trends obtained from sampled data. To this aim, the mass concentrations of $PM_{2.5}$ in the air were analyzed, as well as those of metals, ions, and total carbon within the $PM_{2.5}$. The mean concentration of $PM_{2.5}$ was $22.7{\mu}g/m^3$. The mass composition of $PM_{2.5}$ was as follows: 31.1% of ionic species, 2.2% of metallic species, and 26.7% of carbonic species (EC and OC). Ionic species, especially sulfate, ammonium, and nitrate, were the most abundant in the $PM_{2.5}$ and exhibited a high correlation coefficient with the mass concentration of $PM_{2.5}$. Seasonal variations of $PM_{2.5}$ showed a similar pattern to those of ionic and metallic species, with high concentrations during winter and spring. $PM_{2.5}$ also had a high correlation with the ionic species $NO_3{^-}$ and $NH_4{^+}$. In addition, $NH_4{^+}$ was highly correlated with $NO_3{^-}$. Through factor analysis, we identified four controlling factors, and determined the pollution sources using the United States Environmental Protection Agency(U.S. EPA) pollution profile. The first factor, accounting for 19.1% of $PM_{2.5}$ was attributed to motor vehicles and heating-related sources: the second factor indicated industry-related sources and secondary particles, and the other factors indicated soil, industry-related and marine sources. However, the pollution profile used in this study may be somewhat different from the actual situation in Korea, since it was obtained from US EPA. Therefore, to more accurately estimate the pollutants present in the air, a pollution profile for Korea should be produced.

• Journal of the Korean Geotechnical Society
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• v.37 no.11
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• pp.71-81
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• 2021

The purpose of this study is liquefaction phenomenon was simulated using the 1g shaking table test. Analysis of liquefaction and Re-liquefaction behavior according to the ground conditions was analyzed when an embankment exists above the ground. The soil used in the experiment was silica sand and the ground composition was a liquefied layer of 50cm (Case 1), a non-liquefied layer of 17.5cm and a liquefied layer of 32.5cm (Case 2). The embankment was formed by fixing the height of 10cm and the slope of the slope at a ratio of 1:1.8. For seismic waves, excitation of a 5Hz sine wave was performed for 8 seconds, and a total of 5 case excitations were performed. In Case 1, it was confirmed that liquefaction occurred at all depths during the first vibration excitation at the free-field and that liquefaction did not occur at all depths except 5cm at the third vibration excitation. At the center of the embankment, liquefaction occurred up to a depth of 20cm during the first vibration excitation, and it was confirmed that liquefaction did not occur at all depths except for a depth of 5cm during the second vibration excitation.

• Conservation Science in Museum
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• v.28
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• pp.17-34
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• 2022

This study seeks to identify the material characteristics of earthenware excavated from the Bangi-dong Ancient Tomb No. 3 and the articulated stone-mound tomb of the Seokchon-dong ancient tombs in the Songpa region, and analyze the homogeneity and the firing temperature of the materials used at each excavated site. The remains have been studied relatively recently, and the groups of tombs in which they were found demonstrate the transition of ancient Korean burial systems, and at the same time, provide important archaeological data about those in power at the time. The earthenware pottery excavated from the two sites examined in the study were buried at different times, and it is assumed that they were made by procuring weathered soil of similar gneiss, judging from the behavior of the compatible and incompatible elements and the weathering tendency found by examining the main components. In addition, the examination of the mineral composition and microstructure of clay indicates that the earthenware from Seokchon-dong was fired at 950 degrees Celsius or lower at a relatively early stage. On the other hand, the earthenware from Bangi-dong Tomb No. 3 was confirmed to have experienced temperatures below 850 degrees Celsius and above 1,000 degrees Celsius. However, it is difficult to interpret the difference as the result of the changes in firing temperature throughout the eras. It is expected that it will be possible to interpret the changes in earthenware manufacturing techniques by comparing more diverse earthenware potteries and ancient soils.

• The Journal of Engineering Geology
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• v.32 no.4
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• pp.449-466
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• 2022

The establishment of a complete geological model that includes information about all the various components at a site (such as underground structures and the compositions of rock and soil underground space) is difficult, and geological modeling is a developing field. This study uses commercial software for the relatively easy composition of geological models. Our digital modeling process integrates a model of Jeju Island's 3D geological information, models of cave shapes, and information on the state of a road at the site's upper surface. Among the numerous natural caves that exist in Jeju Island, we studied the Jaeamcheon lava tube near Hallim town, and the selected site lies below a road. We developed a digital model by applying the principles of building information modeling (BIM) to the cave (CaveBIM). The digital model was compiled through gathering and integrating specific data: relevant processes include modeling the cave's shape using a laser scanner, 3D geological modeling using geological information and geophysical exploration data, and modeling the surrounding area using drones. This study developed a global-scale model of the Hallim region and a local-scale model of the Jaeamcheon cave. Cross-validation was performed when constructing the LSM, and the results were compared and analyzed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.22 no.2
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• pp.121-127
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• 1977

Leaf burning due to nitrofenapplication was characterized as brown color spot appearing on the leaf sheath and blade. The spots predominantly appeared around 5-7 cm high above soil surface regardless of different particle size, formulation, application method, or water level. Magnitude and frequency of burn spots increased somewhat as the granular size gets finer, by higher water level, or in transplanted rice compared to directly sown rice when applied at 7 leaf-stage, but there was no indication of increase in leaf burning due to clinging of floating dust to rice plant. When collections from local distributor's stock of TOK 7G, a granular formulation of nitrofen, were analyzed for particle size composition, 98.9% by weight ranged between 9 to 35 meshes, and only about 0.08% by weight was of particles finer than 100 mesh.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.409-419
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• 2023

Acid mine drainage(AMD) treatment is classified as both passive and active treatment. During the treatment, about 5,000 tons of neutralization sludge is generated as a by-product per year in Korea. This study was conducted to evaluate the characteristics of sludge generated from physico·chemical treatment processes as an active treatment from 5 different sources (D, H, S, T, Y) and the possibility of the sludges being recycled. The sludges have a pH range of 5.86 ~ pH 7.89, and a water content range of 51% ~ 82%. Most of particle sizes were less than 25 ㎛. In analysis of inorganic elements, the concentration of Al, Fe, and Mn were between 1,189 mg/kg ~ 129,344 mg/kg, 106,132 mg/kg ~ 338,011 mg/kg, and 3,472 mg/kg ~ 11,743 mg/kg, respectively. The concentration of As and Zn in sludge-T, Cd in sludge-D, Ni in sludge-H, Zn in sludge-S, and Cd in sludge-Y exceeded the soil contamination standards of Korea. The results from 2 separate kinds of leaching test, the Korea Standard Leaching Test(KSLT) and Toxicity Characteristic Leaching Procedure(TCLP), showed that all the sludges met the Korea groundwater standards. From the XRD and SEM-EDS analysis, the peaks of calcite and quartz were found in the sludges. The sludge also had a high proportion of Fe and O, and the majority of the composition was amorphous iron hydroxide.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.111-111
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• 2022

According to data from the Ministry of Environment, food waste accounted for 27% of the nation5 s household waste in 2020, and 4.67 million tons of food waste is being discharged per year. According to the Food Waste Direct Landfill Prohibition Act, food waste must be incinerated, composted, fodder, and decomposed before landfilling. The cost of incineration and landfilling of food waste is considerable. Therefore, through the process of turning food waste into fertilizer, we are going to investigate the limit of crop application and the change in the growth of crops during continuous use of food waste fertilizer. This study investigated the growth of lettuce such as shoot length, root length, leaf number, fresh weight, and dry weight after treating lettuce with food waste dry powder mixed fertilizer. The experiment was carried out continuously in 2021 (1st year) and 2022 (2nd year), and the treatment groups were set to No Treatment (NT), Chemical Fertilizer (CF), Mixed Fertilizer (MF×1), and Mixed Fertilizer×2 (MF×2), was repeated 3 times. As a result of the 1st year growth survey, there was no significant difference between NT and CF in the case of shoot length, but MF×1 and MF×2 were significantly decreased compared to NT. Root length was not significantly different in all treatment groups. As for the leaf number, there was no significant difference between NT and MF×1, but CF and MF×2 were significantly decreased compared to NT. In fresh weight, MF×1 and MF×2 were significantly decreased compared to NT, and in the case of dry weight, there was no significant difference between NT, MF×1, and MF×2. As a result of the 2nd year growth survey, there was a significant difference in CF and MF×2 in leaf number, but there was no significant difference in all treatment groups with respect to shoot length, root length, fresh weight, and dry weight. Through continuous additional research, it is necessary to confirm the change in soil composition and the growth of crops due to food waste fertilizer treatment.