• Korean Journal of Environmental Agriculture
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• v.3 no.1
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• pp.30-35
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• 1984

A freshwater fish carp(Cyprinus carpio) was exposed to two organophosphorus insecticides in laboratory to investigate the potential of its bioconcentration. The results are summarized as follows: Bioconcentration factor of diazinon and fenitrothion after 24-hour exposure at 1 ppm concentration was 31 and 57, respectively, for the whole fish. The factor varied among different tissues of the fish in the decreasing order of viscera>rests>gills>muscle. When the fish was exposed to fenitrothion for 28 days at three different concentrations of 6, 30 and 150 ppb, bioconcentration factor in the whole fish ranged from 96 to 138, with a decreasing tendency at higher water concentration. The pesticide was continuously absorbed by the fish, but reaching an equilibrium at the tissue concentration of about 3.5 ppm.

• Journal of the Korean Chemical Society
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• v.34 no.3
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• pp.267-279
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• 1990

The adsorption mechanisms of phenols on XAD-2 and XAD-7 resins were studied by using the distribution coefficient(log Kd) measured in the optimum adsorption conditions. It was observed that the Langmuir adsorption isotherm, indicating a molecular size-dependent adsorption, was appropriate for characterizing the adsorption behaviors of phenols on XAD-2 and XAD-7 resins. The adsorption energies of phenols on XAD resins were calculated by Lennard-Jones potential equation. In the calculation of the adsorption energy, the molecular radii and dipole moments of the resins and phenols were calculated by their van der Waals volumes and Debye equation, respectively. The stacking factor (F) were determined from the radio of the equilibrium distance to the stacking distance of molecules. In order to explain the adsorption energy calculated from the stacking factor it was compared with the adsorption enthalpy for each of phenols which was experimentally determined by batch adsorption shake method. It was observed that the adsorption enthalpy of phenolate ions on the XAD resins was likely to be more seriously affected by dispersion interaction than by a dipole or a charge interaction.

• Journal of the Korean Geotechnical Society
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• v.37 no.7
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• pp.5-12
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• 2021

When drilling investigations for Rock Slopes are not possible, it is often difficult to calculate the Ground Design Constants required for the Limit Equilibrium Analysis. Therefore, the outcrops or partially cutted Rock Slopes were analysed using JRC and JCS that can be easily and conveniently measured. In particular, the effect of the JRC on the Safety Factor or the Rock Slopes was analyzed intensively, and the results were presented as a relationship formula and Table. When the Rock slope was stable, the JRC increased by an average of 9.0% as the slope height increased, and increased by an average of 29.8% as the slope angle increased. JRC was more sensitive to slope angle changes. The Cohesion corresponding to JRC was calculated from JRC-Fs formula. JRC and Cohesion showed a nonlinear relationship, and the Cohesion was about 8.0% more sensitive to slope height changes than slope angle changes.

• The Journal of the Convergence on Culture Technology
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• v.8 no.1
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• pp.507-512
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• 2022

The subjects of the study are the sedimentary rock slope of the Mesozoic Gyeongsang Supergroup, which has a high risk of failure. The rocks of the slope shall be sandstone, siltstone and dacite, and discontinuities shall develop beddings, shear joints, extension joints, and dacite dyke boundary planes. The type and scale of failure varies depending on the type of rock and the strike/dip of the discontinuities, but the planar failure prevails. Based on the face-mapping data, SMR, physical and mechanical testing of rocks, the critical equilibrium analysis, all representative sections required a countermeasure method because the acceptable safety factor during dry and rainy seasons were far below Fs=1.5 and Fs=1.2. After applying the countermeasure method, both the dry and wet conditions of the slope exceeded the allowable safety factor. In particular, the face-mapping data of the slope-face, the geological cross-sections of several representative sections perpendicular to the slope-face, and the critical equilibrium analysis and the presentation of countermeasure methods that have been reviewed based on them are expected to be reasonable tools for the slope stability.

• Journal of Sericultural and Entomological Science
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• no.12
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• pp.47-50
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• 1970

There are many factors affecting the development of sericultural industry in Korea. The setting of a rational pricing system for sericultural products is one of important activities of the Korean Government to improve the incentives to producers. The determination o： the prices for many years were based on the production costs including a certain level of profits. Some of cost items are in conflict both in cocoon producers and silk-reeling industries. Government officials have to evaluate these conflicting problems and estimate the consequences of their decisions. In this situation the final decision often became political decisions. This analysis is aimed at providing an alternative method of setting the prices of sericultural products. The criteria of the equilibrium employed in this analysis are based on economic principle which equilibrium condition is determined by the relationships between the marginal productivity of input factors and factor prices. In order to obtain the related information Cobb-Douglas'functions were fitted using KIST computer and data were obtained mostly from the Bank of Korea and the Ministry of Agriculture and Forestru, An important assumption is that "Opportunity Costs" of factors input in both cocoon production and silk-Peeling industries are same, The major finding s obtained are as followings. 1) The sum of coefficient of production elastisity in silk-reeling industries is greater than one. Silk-reeling industries are operating under the situation of increasing return to scale and it is, therefore, expected to develop the industries as the capital-intensive large scale. 2) The cocoon producing farmers are under the situations of the decreasing return to scale and it is expected to continue their cocoon farming as the labor-intensive small scale, assuming the present level of production technology. As the development of commercial farming, the resources input in cocoon production will be shifted to the production for higher profitable crops, 3) The price elastisity of production is higher in cocoon production than in silk-reeling industries. It is expected that the price changing effects on domestic production will be resulted from cocoon producers. 4) Based on analysis results of marginal productivities and the opportunity costs of resources, cocoon price for meeting equilibrium price condition is to be increased by 8-16 percent or standard price level of silk increased by 6-8 percent. There were the possibilities of over evaluation on opportunity cost of resources input in silk-reeling industries, or income transfered from the farmers to the industries. It is recommended that the prices for meeting equilibrium price conditions are to be determined by 72 percent for cocoon and 28 percent for silk-reeling costs, based on standard level of the exporting prices.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.28 no.3
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• pp.283-291
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• 2018

Objectives: To monitor the radon concentration level in plants that handle phosphorus rock and produce gypsum board and cement, and evaluate the effective dose considering the effect of radon exposure on the human body. Methods: Airborne radon concentrations were measured using alpha-track radon detectors (${\alpha}$-track, Rn-tech Co., Korea) and continuous monitors (Radon Sentinel 1030, Sun Nuclear Co., USA). Radon concentrations in the air were converted to radon doses using the following equation to evaluate the human effects due to radon. H (mSv/yr) = Radon gas concentration x Equilibrium factor x Occupancy factor x Dose conversion factor. The International Commission on Radiological Protection (ICRP) used $8nSv/(Bq{\cdot}hr/m^3)$ as the dose conversion factor in 2010, but raised it by a factor of four to $33nSv/(Bq{\cdot}hr/m^3)$ in 2017. Results: Radon concentrations and effective doses in fertilizer manufacturing process averaged $14.3(2.7)Bq/m^3$ ($2.0-551.3Bq/m^3$), 0.11-0.54 m㏜/yr depending on the advisory authority and recommendation year, respectively. Radon concentrations in the gypsum-board manufacturing process averaged $14.9Bq/m^3$ at material storage, $11.4Bq/m^3$ at burnability, $8.1Bq/m^3$ at mixing, $10.0Bq/m^3$ at forming, $8.9Bq/m^3$ at drying, $14.7Bq/m^3$ at cutting, and $10.5Bq/m^3$ at shipment. It was low because it did not use phosphate gypsum. Radon concentrations and effective doses in the cement manufacturing process were $23.2Bq/m^3$ in the stowage area, $20.2Bq/m^3$ in the hopper, $16.8Bq/m^3$ in the feeder and $11.9Bq/m^3$ in the cement mill, marking 0.12-0.63 m㏜/yr, respectively. Conclusions: Workers handling phosphorous gypsum directly or indirectly can be assessed as exposed to an annual average radon dose of 0.16 to 2.04 mSv or 0.010 to 0.102 WLM (Working Level Month).

• Tunnel and Underground Space
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• v.11 no.3
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• pp.279-288
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• 2001

Jointed rock mass can be analyzed by either continuum model or discontinuum model. Finite element method or finite difference method is mainly used for continuum modelling. Although discontinuum model is very attractive in analyzing the behavior of each block in jointed blocky rock masses, it has shortcomings such that it is difficult to investigate each joint exactly with the present technology and the amount of calculation in computer becomes trio excessive. Moreover, in case of the jointed blocky rock mass which has more than 2 dominant joint sets, it is impossible to model the behavior of each block. Therefore, a model such as ubiquitous joint model theory which assumes the rock mass as a continuum, is required. In the case of tunnels, unlike slopes, it is not easy to obtain safety factor by utilizing analysis method based on limit equilibrium method because it is difficult to assume the shape of failure surface in advance. For this reason, numerical analyses for tunnels have been limited to analyzing stability rather than in calculating the safety factor. In this study, the behavior of a tunnel excavated in jointed rock mass is analyzed numerically by using ubiquitous joint model which can incorporate 2 joint sets and a method to calculate safety factor of the tunnel numerically is presented. To this end, stress reduction technique is adopted.

• Journal of the Korean Geotechnical Society
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• v.23 no.6
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• pp.97-102
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• 2007

Though the stability analysis of soil slopes widely employs the limit equilibrium method, the study on the jointed rock slopes must consider the direction of joint and the characteristics of Joint at the same time. This study analyzes the result of the change in the factors which show the characteristics of discontinuity and the shape factor of rock slopes, and so on, in an attempt to validate the propriety as to the interpretation of jointed rock slope stability which uses the general finite element program. First, the difference depending on the flow rules was compared, and the factor effect study was conducted. The selected independent variables included the direction of joint which displays the mechanical characteristics of discontinuity, adhesive cohesion, friction angle, the inclination and height of rock slope which reveal the shape of slope and surcharge load. And the horizontal displacement was numerically interpreted at the 1/3 point below the slope, a dependent variable, to compare the relative degree of factor effects. The findings of study on factor effects led to the validation that the result of horizontal displacement for each factor satisfied various engineering characteristics, making it possible to be applied to stability interpretation of jointed rock slope. A modelling is possible, which considers the application of the result of real geotechnical surveys & laboratory studies and the non-linear characteristics when designing the rock slope. In addition, the stress change which may result from the natural disaster, such as precipitation, and the construction, can be expressed. Furthermore, as the complicated rock condition and the ground supporting effect can be considered through FEM, it is considered to be very useful in making an engineering decision on the cut-slope, reinforcement and so on.

• Journal of the Korean GEO-environmental Society
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• v.2 no.4
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• pp.39-50
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• 2001

In this study, in order to investigate the effects of reinforcement length and vertical spacing on the factor of safety, the road embankment reinforced by geogrid was analyzed using RSS(Reinforced Slope Stability) program based on limit equilibrium analysis. The result by computer analysis showed that the factor of safety for reinforced slope increased with increasing length of reinforcement and with decreasing vertical spacing of reinforcement up to certain limit. Also, numerical analysis by FLAC was performed on reinforced slope to evaluate the horizontal displacement, horizontal stress, and distribution of tensile forces of reinforcements in the cases of several reinforcement length. The results of analysis showed that the critical failure mode was toe failure or slope failure and the effect by the additional reinforcement length on the slope stability was negligible under stabilized condition.

• Magazine of the Korean Society of Agricultural Engineers
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• v.24 no.2
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• pp.76-88
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• 1982

The stream morphological characteristics of a basin have important influence upon the analysis of runoff. In this study, the laws of stream morphology-the law of average stream fall and the law of least rate of potential energy expenditure-which were derived based on the analogy of entropy in thermodynamics are introduced and their validity is analysised with the data taken from the topographic maps covering the whole Geum River system. The first law is the Law of Average Stream Fall which states that under the dynamic equilibrium condition the ratio of average fall between any two different order stream in the same river basin in unity. The second law is the law of least rate of energy expenditure which states that all natural streams are intended to choose their own course of flow such that the rate of potential energy loss per unit mass of water this course is a minimum. The parameters representing the morphological characteristics of 13 tributaries in the Geum River system such as stream bifurcation ratio and stream concavity were Computed from the Horton-Strahler's laws and are used to check the law of average stream fall. The result showed that the law of average stream fall agrees reasonably well with law of Horton-Strahler. Concavity of a river basin is shown to be the determinative factor to the formation of a stream system. Concavity of a river basin is shown to be the determinative factor to the formation of a stream system. Based on Horton's Law and the law of average stream fall, longitudinal stream profiles can be calculated.