• Magazine of the Korean Society of Agricultural Engineers
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• v.15 no.4
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• pp.3153-3159
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• 1973

Although standard method of test for liquid limit procedure is issued under the fixed designation KSF-2303 in 1968, for both of general method and on point method, the latter of which is not still favorably used among laboratory engineers with its defficiency of adquate informations. This study intended as to furnish proper information to the laboratory engineers for the use of one point liquid limit test with full advantages of time-saving and labor-saving. further more, the following conversion formula to the one point method VS. general method is presented by the results of analytical study on 1017 Soil sampls existing liquid limit test data The formula is; $$W_L = W(\frac{N}{25})^{0.118}$$ The conversion factor (table-4) is also attached for the convenience of the users.

• Journal of the Korean Geotechnical Society
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• v.31 no.10
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• pp.5-16
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• 2015

Considering the conversion of the Korea Construction Standards to Limit State Design (LSD), we analyzed the resistance bias factor for pullout resistance, as a part of the development of the Load and Resistance Factor Design (LRFD) for soil nailing; very few studies have been conducted on soil nailing. In order to reflect the local characteristics of soil nailing, such as the design and construction level, we collected statistics on pullout tests conducted on slopes and excavation construction sites around the country. In this study a database was built based on the geotechnical properties, soil nailing specifications, and pullout test results. The resistance bias factors are calculated to determine the resistance factor of the pullout resistance for gravity and pressurized grouting method, which are the most commonly used methods in Korea; moreover, we have relatively sufficient data on these methods. We found the resistance bias factors to be 1.144 and 1.325, which are relatively conservative values for predicting the actual ultimate pullout resistance. It showed that our designs are safer than those found in a research case in the United States (NCHRP Report); however, there was an uncertainty, $COV_R$, of 0.27-0.43 in the pullout resistance, which is relatively high. In addition, the pressurized grouting method has a greater margin of safety than the gravity grouting method, and the actual ultimate pullout resistance determined using the pressurized grouting method has low uncertainty.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.4
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• pp.380-383
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• 1998

For the evaluation of the quality of compost, the determination of C/N ratio is mandatory in Korea. Accordingly it is necessary to measure the total carbon content of compost for the quality control of composts. It is, however, not easy to measure the carbon content of compost. For practical purposes total carbon content of compost can be estimated from the total organic matter content, which is estimated by way of ignition loss. For this, it is necessary to establish the factor for conversion of organic matter into carbon. We studied the relationship between the organic matter content determined by ignition method and total carbon content measured by elemental analyzer using 160 compost sample collected from the markets. The relationship between the carbon content and organic matter in those composts was found to be "y(% carbon)=1.995+0.484%(% organic matter)"($r^2=0.943$). This result suggests that total carbon contents of composts can be estimated from the organic matter content.

• Journal of Korean Society for Atmospheric Environment
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• v.11 no.2
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• pp.191-198
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• 1995

In order to evaluate the distribution and behaviour of atmospheric particulate metals in high-altitude area, we collected 22 aerosol samples using a high volume air sampler at Soback Mt. Meteorological Observation Station from Jan. to Nov. 1993 and analysed for metals (Al, Fe, Mg, Na, Ca, Mn, Co, Ni, Cu, Zn, Cd, and Pb) with ICP/AES and ICP/MS. Although sampling site is located in high-altitude and far from local sources of atmospheric pollutants, enrichments of metals are 2 times higher than those of western coastal reural area. This fact may imply that of metallic pollutants in the coastal rural site were came from further western side (e.g. China), atmospheric metals in this study area contain the signal of metropolitan cities located in the main wind direction (NNW). Sea salts are negligible in the aerosol particle population because reference elements of sea salts (Na, Mg) are all originated from soil particles. The contents of soil particles in aerosols are highest in spring and lowest in winter. Atmospheric enriched elements (Ni, Cu, Zn, Cd and Pb) are diluted with soil particles, especially during the yellow sand period. The results of factor analysis suggest possibility of interpreting their chemical significance in terms of sources (soil, pollutants) and gas-particle conversion processes (formation of ammonium sulfates, ammonium nitrates and/or their mixtures).

• Journal of Korean Society of Forest Science
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• v.83 no.3
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• pp.322-330
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• 1994

The Universal Soil Loss Equation (USLE) has been widely used to predict long-term soil loss by incorporating several erosion factors, such as rainfall, soil, topography, and vegetation. This study is aimed to introduce the LISLE within geographic information system(GIS) environment. The Kwangneung Experimental Forest located in Kyongki Province was selected for the study area. Initially, twelve years of hourly rainfall records that were collected from 1982 to 1993 were processed to obtain the rainfall factor(R) value for the LISLE calculation. Soil survey map and topographic map of the study area were digitized and subsequent input values(K, L, S factors) were derived. The cover type and management factor (C) values were obtained from the classification of Landsat Thematic Mapper(CM) satellite imagery. All these input values were geographically registered over a common map coordinate with $25{\times}25m^2$ ground resolution. The USLE was calculated for every grid location by selecting necessary input values from the digital base maps. Once the LISLE was calculated, the resultant soil loss values(A) were represented by both numerical values and map format. Using GIS to run the LISLE, it is possible to pent out the exact locations where soil loss potential is high. In addition, this approach can be a very effective tool to monitor possible soil loss hazard under the situations of forest changes, such as conversion of forest lands to other uses, forest road construction, timber harvesting, and forest damages caused by fire, insect, and diseases.

• Journal of Korean Society of Forest Science
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• v.103 no.1
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• pp.37-42
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• 2014

Fine root distribution was investigated in Pinus densiflora stands using soil core sampling and minirhizotrons, and conversion factors and regression equations were developed for converting minirhizotron data into fine root biomass. Fine root biomass was measured by soil core sampling from October, 2012 to September, 2013 once a month except for the winter, and surface area of fine roots was estimated by minirhizotrons from May to August, 2013 once a month. Fine root biomass and surface area were significantly higher in the upper soil layers than in the lower soil layers. Fine root biomass showed seasonal patterns; the mean fine root biomass ($kg{\cdot}ha^{-1}$) in summer (3,762.4) and spring (3,398.0) was significantly higher than that in autumn (2,551.6). Vertical and seasonal patterns of fine root biomass might be related to the soil bulk density, nutrient content and temperature with soil depth, and seasonal changes of soil and air temperature. Conversion factors (CF) between fine root surface area from minirhizotron data and fine root biomass from soil core sampling were developed for the three soil depths. Then a linear regression equation was developed between the predicted fine root biomass using CF and the measured fine root biomass (y = 79.7 + 0.93x, $R^2=0.81$). We expect to estimate the long-term dynamics of fine roots using CF and regression equation for P. densiflora forests in Korea.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.170-173
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• 2011

국내 풍화지반의 토량환산계수를 정확하고 합리적으로 추정하는 것은 공사의 성패에 있어 매우 중요한 사항이다. 하지만 현업에서는 풍화지반의 풍화도를 정량화하는 것이 어렵고, 토량환산계수를 적용 시 외국의 기준을 사용하는 경우가 빈번하다. 뿐만 아니라, 국내 풍화지반의 토량환산계수에 관한 연구는 아직 미비하여, 끊임없이 토량환산계수의 정확성 및 사용성에 대해 문제 제기가 있어 왔다. 이에 본 연구에서는 TEPS (Tunnel Electrical resistivity Prospecting System)를 이용하여 화강암의 풍화 정도와 전기비저항의 상관관계를 도출하고 풍화지반 내 흙이 차지하는 비율(S/W 비)을 전기비저항과 개괄적으로 상관관계를 맺어 전기비저항을 이용하여 토량환산계수를 산정하는 방법을 제안하였다. 현장 관리자가 풍화지반에서 쉽게 토량환산계수 및 토공량에 관한 정보를 획득할 수 있도록 풍화지반 토공관리프로그램(WEMP)을 개발하고 토량환산계수 측정시스템을 설계하였다.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.955-960
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• 2012

In most agricultural soils, ammonium ($NH_4{^+}$) from fertilizer is quickly converted to nitrate ($NO_3{^-}$) by the process of nitrification which is crucial to the efficiency of N fertilizers and their impact on the environment. The salinity significantly affects efficiency of N fertilizer in reclaimed tidal soil, and the soil pH may influence the conversion rate of ammonium to nitrate and ultimately affect nitrogen losses from the soil profile. Several results suggest that pH has important effects on recovery of fall-applied N in the spring if field conditions are favorable for leaching and denitrification except that effects of soil pH are not serious under unfavorable conditions for N loss by these mechanisms. Soil pH, therefore, deserves attention as an important factor in the newly reclaimed tidal soils with applying N. However, fate of N studies in a newly reclaimed tidal soils have been rarely studied, especially under the conditions of saline-sodic and high pH. Therefore, understanding the fate of nitrogen species transformed from urea treated into the reclaimed tidal soil is important for nutrient management and environmental quality. In this article, we reviewed yields of rice and fate of nitrogen with respect to the properties of reclaimed tidal soils.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.3
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• pp.163-172
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• 2015

This study examined the potential effects of urban growth on streamflow in the Gyungan River watershed, Korea, using urban containment scenarios. First, two scenarios (conservation and development) were established, and SLEUTH model was adapted to predict urban growth into the year 2060 with 20 years interval under two scenarios in the study area. Urban growth was larger under scenario 2, focusing on development, than under scenario 1, focusing on conservation. Most urban growth was predicted to involve the conversion of farmland, forest, and grasslands to urban areas. Streamflow in future periods under these scenarios was simulated by the Soil and Water Assessment Tool (SWAT) model. Each scenario showed distinct seasonal variations in streamflow. Although urban growth had a small effect on streamflow, urban growth may heighten the problems of increased seasonal variability in streamflow caused by other factor, such as climate change. This results obtained in this study provide further insight into the availability of future water resource and can aid in urban containment planning to mitigate the negative effects of urban growth in the study area.

• Journal of Radiation Protection and Research
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• v.13 no.2
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• pp.57-66
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• 1988

A series of experiments is performed to measure radon concentration in the near-surface soil gas at the four locations (Cheju-Si, Seoguipo-Si, Taejeong-eup, Seongsan-eup) in Cheju Island, using CR-39 detectors placed inside radon cups. Two types of radon cups are installed in shallow holes of about 15 cm in diameter and 50cm in depth. The optimum etching conditions, i.e., the concentration of NaOH solution, etchant temperature and etching time, are found to be 625N, $70^{\circ}C$ and 5.5 hours for CR-39 detectors. A typical conversion factor of radon cup is calculated as $$1track/mm^3{\cdot}30day=0.059Bq/{\ell}$$. Average radon concentrations over 30 days measured in Cheju Island from May 1, 1987 to April 23, 1988 are $3.1{\pm}0.3Bq/{\ell}$ for open radon cups and $1.7{\pm}0.2Bq/{\ell}$ for closed radon cups.