• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.4
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• pp.156-166
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• 2000

This study was carried out to provide the information on seasonal variations of water content under highway asphalt pavements which influence on the dynamic behaviour and durability of pavements, and to assess the correlation between water content and soil or meteorological factors. Total eight sites for water content measurement which included fives sites in Kyungbu, two sites in Honam, and one site in Youngdong Highway were selected considering the variations in geology, topology and meteorology factors over all the country. Water contents under asphalt pavements were measured up to 170 cm depth every two week for total 13 months of August 1992 through September 1993 using neutron moisture meter(CPN-503DR). The range of water content ($\theta$$_{w}$) at the upper soils of above 50 cm depth was 7~12% and was not quite different regardless of sites, except for Iseo site. However, soil water contents below 60 or 70 cm depth were significantly different between the measurement sites, that is, the lowest water content was 5% at Kyungsan site and the highest water content was 20% at Iseo site. For all the sites, seasonal variations in water content during the experimental period were little, their range was within only 1 to 4%. Seasonal variations of water content in original or cutting area, which were 4% more or less, were slightly larger than in bedding areas, which were below 2%. Water contents under asphalt pavements had statistically significant positive correlations with silt and clay content in soil, but there were little correlations between water content and meteorological factors such as precipitation, relative humidity, mean air temperature, and wind velocity.

• Journal of the Korean GEO-environmental Society
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• v.15 no.2
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• pp.17-25
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• 2014

In the present study, it were performed an unconfined compression test and a field applicability test according to a mixed ratio of SS, soil type and curing period to analyze strength and deformation characteristic in order to evaluate engineering characteristics of soil mixed pavements using the eco-friendly soil stabilizer (SS). The test results revealed that SS mixed soil shows fast strength development at the initial curing time while 28-day strength amounted for 97% of the final strength. Furthermore, coarse-grained dredged sand (DS) and weathered granitic soil (WGS) have a larger ratio of deformation coefficient with respect to unconfined compressive strength than fine-grained dredged clay (DC) and organic soil (OS). Moreover, a comparison test between natural and forced drying conditions was conducted and test result showed 54% to 67% of strength degradation while having 55% to 63% of strength degradation in the freezing and thawing test result. Finally, a repeated loading test result showed that DS experiences up to 35% of strength reduction compared to initial strength under 10,000 times loading in maximum. Thus, it was validated that an appropriate amount of fine-grained sand is necessary to secure resistance capability to repeated loading.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.4
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• pp.365-376
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• 2021

In general, domestic streams and rivers are composed of alluvial rivers consisting of sand and gravel beds. These rivers can cause erosion and riverbed changes due to sudden changes in flow rates, such as floods, torrential rains, and heavy rains. In particular, there are various types of erosion, such as contraction erosion caused by changes in river shape, or local erosion occurring around obstacles such as piers, abutments or embankments. In addition, river changes can occur in various forms, such as static or dynamic periods, due to limitations such as flow rate, velocity, and shear stress. This study focused on the erosions of embankments directly related to human casualties among various river structures, and evaluated limit velocities and critical shear stress in order to identify changes in strength of natural materials by identifying the characteristics of natural hoan materials and resistance to erosions. In particular, the limitations of materials according to the type of materials in the river, characteristics of particles, and size of particles were studied using Soil loss, which is a change in the volume of the revetment material, and it is intended to be used as basic data for river design and restoration.

• Journal of Korean Society of Forest Science
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• v.111 no.3
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• pp.357-364
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• 2022

We investigated the early growth characteristics of Quercus rubra planted in six regions (Hwaseong, Yangpyeong, Pyeongchang, Samcheok, Chungju, and Gimje) in South Korea in relation to soil physicochemical properties and meteorological factors. Q. rubra (1-0) were planted at a density of 3,000 trees ha^-1. The average height, root collar diameter (RCD), and volume of 8-year-old Q. rubra planted in 2014 were 3.52 m, 3.84 cm, and 0.0023 m³, respectively. The growth parameters of Q. rubra were the highest and lowest in Hwaseong and Pyeongchang, respectively. Correlation analysis among the soil physicochemical properties, meteorological factors, and plantation growth characteristics found that pH was the only soil factor negatively correlated with RCD, and the other soil factors were not significantly correlated with the growth characteristics. However, growth characteristics were positively correlated to average temperature from March to October and daily maximum temperature; and they were negatively correlated to altitude, topology, and the number of rainy days from March to October. In particular, the trees planted in Hwaseong area showed the best early growth characteristics because this area had the highest daily maximum temperature, the x average temperature from March to October, the low altitude, and it is located close to the foot of a mountain. In Pyeongchang, the early growth characteristics were negatively affected by winter cold damage because of the high altitude, low daily minimum temperature, and damage by wild animals. In Hwaseong, meteorological factors such as temperature and altitude were more highly correlated to growth characteristics of Q. rubra than the physicochemical soil properties. These results will provide useful information for determining suitable sites for Q. rubra plantations and for predicting early growth characteristics in response to environmental factors.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.449-453
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• 2005

하천의 물리적 생태적 특성에 대한 연구는 하천유형분류의 기초 자료로서 큰 의미가 있다. 그러나 국내의 경우 이를 위한 하천의 조사는 매우 드물며, 국부적이었다. 더욱이 이러한 생태적 물리적 특성을 근거로 한 하천 유형적 특성을 연구한 사례는 없었다. 본 연구에서는 하천의 유형을 분류하는 것은 아니지만 하천을 더욱 효율적으로 계획하고 관리하는데 필요한 기초자료를 구축하고자 하였다. 그리하여 1차적 연구로 자연환경이 유사한 하천들을 일시에 선정하여 동일한 방법으로 각 하천의 물리적 생태적 특성을 조사하고 평가하여 대상 하천의 공통적 특성을 가려내고자 하였다. 이와 관련하여 본 연구에서는 하천의 물리적 구조조사법을 유럽공동체에서 사용하는 기준과 방법에 따라 시범적으로 실시하여 국내하천의 하천환경조사를 위한 적용성 여부도 진단하고자 하였다. 하천의 물리적 구조등급이란 하천의 공간적 환경과 저수로 하상재료의 물리적 차이를 의미하는 것으로 하천 자체는 물론 하천범람지에 영향을 주는 생태적 기능의 수리 특성, 하천의 물리 특성, 수생태 특성 등을 포괄하게 된다. 따라서 하천의 물리적 구조등급은 하천구조의 생태적 질과 하천구조로 나타나게 되는 동적 과정(dynamic process)의 질을 평가하는 척도가 될 수 있다. 본 연구에서는 남한강수계의 청미천, 양화천, 복하천을 대상으로 물리적 구조조사법과 식생조사를 병행하였으며 이로부터 하천의 물리적 구조등급이 수질등급과 정량적이지는 않지만 전반적인 하천의 생태성 또는 자연도를 가늠할 수 있는 하나의 지료로 활용할 수 있음을 알 수 있었다.양토를 기준으로 할 때 강우량과 침투수의 관계는 $I_{10}(mm)=0.44R(mm)+5.8(r^2=0.55)$이었다. y절이 발생한 이유는 이전 강우에 의해 침투되고 있는 물이 있음을 함축하며 기울기 0.40은 강우의 $40\%$가 지하로 침투하였음을 의미한다. 침투수량은 토성별로 양토를 1.0으로 기준할 때 사양토가 1.12로 가장 컸고, 식양토 0.94, 식토 0.91로 평가되었다. 이는 토성간의 침투속도 및 투수속도의 경향이 반영된 것이다. 경사에 따라서는 경사도가 증가할수록 지수적으로 감소하였으며 $10\% 경사일 때를 기준으로 $I(mm)=I_{10}{\times}1.17{\times}e^{-0.0164s(\%)}$로 나타났다. 같은 조건에서 강우량과 유거수의 관계는 $Ro_{10}(mm)=5.32e^{0.11R(mm)}(r^2=0.69)$로 나타났다. 이는 토양의 투수특성에 따라 강우량 증가에 비례하여 점증하는 침투수와 구분되는 현상이었다. 경사와 토양이 같은 조건에서 나지의 경우 역시 $Ro_{B10}(mm)=20.3e^{0.08R(mm)(r^2=0.84)$로 지수적으로 증가하는 경향을 나타내었다. 유거수량은 토성별로 양토를 1.0으로 기준할 때 사양토가 0.86으로 가장 작았고, 식양토 1.09, 식토 1.15로 평가되어 침투수에 비해 토성별 차이가 크게 나타났다. 이는 토성이 세립질일 수록 유거수의 저항이 작기 때문으로 생각된다. 경사에 따라서는 경사

• Journal of Conservation Science
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• v.36 no.5
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• pp.421-429
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• 2020

This study examined the manufacturing process of a furnace wall excavated from the Songdu-ri Site in Jincheon, and the difference in material composition between the 11 layers of the wall using physicochemical analyses. Based on microstructure observations, these layers could be largely divided into three groups: an undercalcined first layer, calcined second to ninth layer with evidences of partial heat, and non-fired soil layers from the tenth to the eleventh layer. Particle size analyses revealed that the fired layer constituted a relatively higher content of coarse sand than the non-fired layer. This difference was further confirmed by the results of the curvature coefficient analysis. An analysis of the constituent minerals showed similar overall XRD diffraction patterns between the different layers, but variations in the intensity of the low-temperature and high-temperature minerals. This indicates that the degree of heat was different. The thermal analysis results demonstrated that the heating peak of mullite was only reached in the first and second layers of the wall, thus implying these as the layers to be finally used. Consequently, no significant difference could be observed between the materials of the various layers of the wall. Thus, it can be suggested that the furnace wall was constructed using clay, which had a composition similar to that of the soil present in the area. However, the shape and characteristics of the constituent particles between the layers displayed partial variations, and it is possible that some external materials might have been added.

• Korean Journal of Plant Resources
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• v.19 no.1
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• pp.68-75
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• 2006

This study was conducted to investigate the combination of proper culture medium for differentiation culture of Chrysanthemum zawadskii var. latilobum KITAMURA. The combinations of culture medium were consisted with an inorganic materials such as vermiculite, perlite, saprolite, sand and upland top soil, and with an organic materials such as peat-moss, leaf mold and compost. For the plant growth characteristics, the plant height, number of tiller, root length and root weight in the combination of leaf mold was relatively great as compared to the treatment with peat-moss and compost. It was considered that humus might be contributed to improve the physical properties of soil as well as the sequential nutrient supply. For the combination of peat-moss, the plant growth was not good because of not sufficient nutrient supply, Also, the plant growth in the treatment of compost was so bad because of enhancement of culture medium pH 8.9 and increasement of phosphorous content.

• Korean Journal of Organic Agriculture
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• v.22 no.4
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• pp.731-742
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• 2014

In the current study, we investigated effects of a combination of earthworm casting, environment-friendly by-product fertilizer, and cultivation soil of Gymnocalycium mihanovichii in a heavy fertilizing culture on diameter, height, numbers of tubercles, and chemical properties of soil thereby elucidating optimal mixture ratio for securing production as well as providing nutrients throughout cultivation period. The Gymnocalycium mihanovichii var 'Ihong', one of grafted cactus for export (Rootstock: 9 cm, Scion: $1.5{\times}1.3cm$ grafted cactus) was cultured in plastic houses of Agricultural Technology Center located in Naegok-dong, Seocho-gu, Seoul from June, 2013 through December, 2013. For the control group, a mixture of sand and fertilizer (50:50) was used as this ratio is widely utilized in farmhouses. In contrast, a variety mixtures of sand and earthworm casting that was produced with food wastes was compared; the mixture ratios were 80:20, 60:40, 40:60, 20:80, and 0:100 and pH for these mixtures were found to be similar each other (ranging between 7.1 and 7.4) which is in an appropriate range (pH 6.5-7.5) for cultivation of G. mihanovichii. The organic content was increasing along with increasing contents of earthworm casting ratio while it was lower than the treatment practice group (32-43 mg/kg vs. 55 mg/kg). The content of exchangeable cation was also increasing as the ratio of earthworm casting was elevated; although levels of $K^+$, $Na^+$, and $Mg^{2+}$ were lower than the treatment practice group, the level of $Ca^{2+}$ was higher ($9.1cmol^+/kg$ and $11.5-33.7cmol^+/kg$ in the treatment practice group and the earthworm casting group, respectively). Three months after grafting, diameters of G. mihanovichii were compared with the control group; consequently, there was a significant difference noted in between the earthworm casting group and the control group (31.39 mm vs. 32.46-37.59 mm). After 5 months, growth characteristics of G. mihanovichii were evaluated. Similarly, the diameter of G. mihanovichii was significantly increasing in the group with higher ratio of earthworm casting treatment (32.63 mm vs. 32.49-37.59 mm). The height of tubercles was 2.63 mm in the control group while it was significantly elevating along with the ratio of earthworm casting mixture. The more numbers of tubercles, the more incomes for farm-houses; as results, higher mixture ration of earthworm casting resulted more numbers of tubercles compared to the control group (2.7 vs. 3.2-8.3 ea). In particular, in the earthworm casting groups with 80% and 100% ratios, the numbers of tubercles were 6.2 and 8.3 ea, respectively, which is 2.5 times more than those of the control group. These results indicate that earthworm casting treatment may be utilized in G. mihanovichii farming houses for short term production of tubercles. In the group with 40% and 60% of earthworm casting mixture, the numbers of tubercles were found to be 4.5 and 4.8 ea, respectively which is higher than the control group as well; in these groups, there were no issues with soil drainage as well as moss formation. Given the analysis results of growth characteristics of G. mihanovichii, it was concluded that 40% and 60% of earthworm casting mixture might be the optimal ratios.

• Journal of Conservation Science
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• v.18 s.18
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• pp.97-104
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• 2006

Absolute ages for three pieces of organic materials such as wood and shell were determined with radio-carbon concentrations and two potsherds with thermoluminescence measurements. Radiocarbon contents of each sample were compared with those of modern standard oxalate(NBS SRM4990C) and calculated radiocarbon ages of them. Quartz grains with diameter of $90\sim150{\mu}m$ were extracted from potsherds and used for measuring the archaeodose. Annual dose were calculated with measuring the alpha count rates and water contents and analysing $K_2O$ concentration of both potsherds and soils. Radiocarbon ages of organic materials were in the ranges of $4\sim2C$ BC and Quartz grain techniques for thermoluminescence dating showed 170 BC ud 210 BC respectively. It was found that the results of radiocarbon dating and TL dating were accorded with each other. But the deviations of TL dating have shown 13% and 20% respectively. It need to reduce the deviations.

• Journal of the Korean Geosynthetics Society
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• v.19 no.1
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• pp.25-33
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• 2020

To improvement the swelling characteristics of the existing cutoff wall against the moisture, the permeability of the sand, calcium bentonite and solidifier mixture according to the contact with trichloroethylene (TCE) was evaluated. Characteristics analysis and the permeability test of the research materials were performed. The permeability was decreased as the mixing ratio of the calcium bentonite was increased and it was increased as the mixing ratio of the solidifier was increased. In conclusion, when mixing 15% of calcium bentonite and more than 30% of solidifier, the permeability coefficient in the underground water movement was analyzed as more than α × 10^-4 cm/sec showing that it does not block the underground water movement. In addition, as the permeability coefficient of mixtures after TCE reaction was analyzed as less than α ×10^-7 cm/sec, it satisfied the condition of blocking layer (less than 1.0 × 10^-6 cm/sec). Therefore, the calcium bentonite and solidifier can be utilized as barrier that showing the characteristic of percolation ability conversion in soil and underground water contaminated with TCE.