• Journal of Korean Society of Environmental Engineers
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• v.29 no.8
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• pp.909-914
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• 2007

Fluorine compounds are the essential chemicals for wet processes of semiconductor and LCD production line. Problems of conventional treatments for fluoride wastewater are their high operation costs and low fluoride removal capacity. In this study, cement paste containing various Ca-bearing hydrates such as portlandite, calcium silicate hydrate(CSH), and ettringite was investigated for fluoride removal. The objectives of this study are to assess the feasibility of using cement paste cured mixture of cement and water as an alternative agent for treatment of fluoride wastewater and to investigate fluoride removal capacity of the cement paste. The performance of cement paste was comparable to that of lime in the kinetic test. In column experiment where the effluent fluoride concentrations were below 0.5 mg/L. Then the leached calcium reached the maximum level of 800 mg/L. The nitrate reduced to the level of less than 10 mg/L. Nitrate in the wastewater was exchanged with interlayer sulfate of these cement hydrate LDHs. Phosphate concentration could be reduced to 10 mg/L by forming calcium phosphate. These results indicate that the cement paste generally has advantageous characteristics as an economical and viable substitute for lime to remove fluoride.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.72-79
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• 2010

The significant of continuous welded rail (CWR) management is growing because KORAIL has the plan to convert the whole of conventional railway lines into CWRs through continuous activities since constructed the CWR track with 1.8km in Gyeongbu line in 1966. The CWR recently is needed a efficient management method because it is difficult to manage the CWR by the poor of technic and equipment, limited maintain labor force and shorted the maintain work time of CWR caused by industrialization, greenhouse effect and global warming In this point, The 70ton Tenser's which is using in the rail site has been analysised with no extra tenser's capacity in case of the under low temperature and exceed the length of 1km as a result of reviewing the CWR-related rules and standards, a series of records of safety accidents, operation obstacles, and the situation of broken rails published by KORAIL, existing rail temperature measurements, and CWR researches. Therefore avoid the excessive plan of the first set-up section, choice the proper time in the normal temperature that is possible to weld the rail, turning the difference of rail temperature and Installation temperature down is desirable.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.809-819
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• 2004

In this paper, in order to exclude the expansion of M/W relay frequency or its new frequency assignment possibly, we analyzed a possibility of substituting M/W system by B-WLL or optical fiber network regarding service quality and economical points. To define the target of service quality, pre-condition and analysis method for the selected media have been derived to compare each other. E1 transmission with BER 10$^{-1}$ was chosen as a reference capacity, and service distance was calculated f3r the selected media as a function of availability. Also from the economical point we considered 3 systems such as optical fiber, M/W, and B-WLL based upon basic system structure, and analyzed them for various line configurations of fiber optic and B-WLL according to service period, system capacity, transmission distance, and data rate. It was confirmed that B-WLL can provide quality of service with 99.999 % availability within 1.6 km cell radius, and for optical fiber substitution, the leased fiber conduit on an electric pole is more economical than M/W system irrespective of service period, but in case of directly digging for underground conduit, it turned out ineffective regardless of cabling duct types.

• Journal of Environmental Policy
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• v.11 no.3
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• pp.49-65
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• 2012

Road traffic noise is closely related to road traffic environment, including traffic volumes by type and travel speed. In this study, we stated some issues and analyzed the relationships between road traffic noise and traffic flow characteristics. First, in attempt to find the answer to the question "When does the loudest traffic noise occur?" we reviewed the issue in the terms of traffic flow. As a result of analyzing level of service through Korea Highway Traffic Noise model, the actual maximum noise occurred in level of service D rather than level of service E, on the capacity state. It shows that maximum noise would be most likely to occur right before and after the peak hours. Second, this paper was looking for the method of a more easy and accurate traffic speed estimation to predict traffic noise. This paper proposed sketch planning techniques of speed-volume curve by level of service on Korea Highway Capacity Manual. As a result of trend line modeling, it was judged that quadratic form is a suitable function, and coefficient of determination ($R^2$) was higher than 0.96, respectively.

• Land and Housing Review
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• v.2 no.2
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• pp.195-204
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• 2011

During mechanical demolition of RC structures, weights of dismantling equipment and demolition waste of building are applied to unexpected load which did not be considered during the design of structural member. Nevertheless, the loading of dismantling equipment and dismantling process are mainly dependent on field managers' field workers' or experiences without considering safety of structural member by a structural engineer. It is urgently required that reflecting actual circumstance of mechanical demolition, safety evaluation method to evaluate the safety and the guideline for appropriate capacity of structural member to support dismantling equipment weight, be provided. Through site investigation and questionnaire on field workers, this paper proposed demolition waste load, load factor, strength reduction factor, and so on. These are essential to safe evaluation of a building, ready to demolition. Considering actual circumstance of mechanical demolition, safety evaluation method of building and design method of slab and beam was suggested to a dilapidated building. An capability to loading of dismantling equipment was proposed, applied to RC slab and RC beam. Therefore, the suggested safety evaluation method and the guideline for an capability to loading of dismantling equipment weight can reasonably evaluate the capacity of structural member in demolition and use effectively as increasing efficiency and improving safety of demolition through proper management of dismantling equipments.

• Analytical Science and Technology
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• v.11 no.3
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• pp.179-188
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• 1998

The capacity factor of fifteen phenol derivatives was determined with respect to the concentration of ${\alpha}$- or ${\beta}$-cyclodextrin [CD], the type as well as the content of organic solvent in the mobile phase, and the temperature. The effect of the inclusion complex formation between solutes and ${\alpha}$- or ${\beta}$-cyclodextrin on their retention and selectivity has been investigated. The inclusion effect of ${\beta}$-cyclodextrin was the most effective in aqueous methanol, whereas only a poor effect was observed in aqueous tetrahydrofuran and aqueous acetonitrile. A plot of the reciprocal of the capacity factor against $[CD]_T$ gives a straight line and the dissociation constant, $K_D$ of the inclusion complex can be calculated from the slope. It was possible to estimate the $k_D$ values in 100% water from a linear plot of $pK_D$ vs. water content in the solution by extrapolation. The separation factor, ${\alpha}$, of two compounds has been found to be affected not only by the $[CD]_T$ but also by their $K_D$ values. Under optimum conditions, some mixtures of phenol derivatives were able to separate successfully.

• Geotechnical Engineering
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• v.10 no.2
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• pp.25-40
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• 1994

In order to investigate behavior of lateral flow by plasticity of soils and construction control due to it, in the case of unsymmetrical surcharge load on the soft soils, we examine the existing theoretical background, and compared and analysed the experimental results by model test. After model test fabricated by model test apparatus, which made full remolding samples of soft soils, we observed the state of behavior for deformation with increasing load step to constant time interval. The critical surcharge and ultimate capacity showed tendency to approach to the proposed value of Jaky and Meyerhof, and the lateral flow pressure of which the maximum value was acted on the depth calculated by z/H=0.26+1.71cu and one third value of the maximum lateral flow pressure acted on the ground surface, approach the trapezoid distribution And maximum lateral flow pressure will be calculated by proposed equation of Hong or simple equation which($\alpha=0.4$) the flow pressure coefficient . of proposed equation by Tschebotarioff exchanged to($\alpha=K_0$) . Basides, the failure surcharge by [(q/$y_m$)-q] and [$S_y-(y_m/S_y)$] showed the smaller than ultimate bearing capacity, especially failure criteria line of control diagram of [$S_y(y_m/S_y)$] will be calculated by following equation. $S_y.=3.15exp[-0.58(y_m/S_y)$

• Journal of Korea Water Resources Association
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• v.50 no.12
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• pp.837-847
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• 2017

Land Surface Model (LSM) was developed for the Soyang river basin located in Korean Peninsula to clarify the spatio-temporal variability of hydrological weather parameters. Variable Infiltration Capacity (VIC) model was used as a LSM. The spatial resolution of the model was 10 km and the time resolution was 1 day. Based on the daily flow data from 2007 to 2010, the 7 parameters of the model were calibrated using the Isolated Particle Swarm Optimization algorithm and the model was verified using the daily flow data from 2011 to 2014. The model showed a Nash-Sutcliffe Coefficient of 0.90 and a correlation coefficient of 0.95 for both calibration and validation periods. The hydrometeorological variables estimated for the Soyang river basin reflected well the seasonal characteristics of summer rainfall concentration, the change of short and shortwave radiation due to temperature change, the change of surface temperature, the evaporation and vegetation increase in the cover layer, and the corresponding change in total evapotranspiration. The model soil moisture data was compared with in-situ soil moisture data. The slope of the trend line relating the two data was 1.087 and correlation coefficient was 0.723 for the Spring, Summer and Fall season. The result of this study suggests that the LSM can be used as a powerful tool in developing precise and efficient water resources plans by providing accurate understanding on the spatio-temporal variation of hydrometeorological variables.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.4
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• pp.292-303
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• 2011

A new type of sand bypassing system is proposed for recovering the eroded beach in this study. This system provides an added methodology to the soft defence which is main recovery method for the coastal shore protection in the world. The study proposes a conceptional design and manufacturing procedure for the relatively small size machine of sand bypassing. In order to get the discharging volume information, the power capacity of the system is tested in the field. The discharge rate of the new system shows up to the expected maximum of 618 ton/hr which is 9.6% lower than that by theoretical calculation. It gives a resonable agreement in this system when the flow is assumed to be of the high density. In this study, the delivering volume of sand is estimated according to the discharge rate. The combination of 300 mm(12 inch) intake and 250 mm(10 inch) discharge pipe line has the pumping capacity of $103\;m^3/hr$ which is nearly the same as that of South Lake Worth Inlet sand bypassing system, Florida, U.S.A.. The proposed system added the mobility to its merit. The unit price of Florida's sand bypassing is $$8~9/m^3$ (US). The system would be economically suitable for small volume of sand because no additional equipment is necessary for the intake. The diesel fuel of 25~30 l/hr was consumed during the system operation. The multiple working system would be the next investigation target for large volume of sand.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.995-998
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• 2007

The number of households old over as much as 20 years is expected to get increased rapidly more than 1,000,000(1 million). As a measure to this fact remodeling is being revitalized over the country. parking lots expansion actually takes up a great deal of weight among the requirement for remodeling. When constructing a parking lot for enlargement, the way of going into the main building determines such construction features as selection of Retaining Wall Method, installation of an elevator, parking measure of capacity, etc. This study derived the affecting factors for selecting the way of going into the main building when constructing an underground parking lot. In a research way, we examined the features on each method of going into the main building in an apartment complex through an in-depth interview with some experts after investigating the method of enlarging an underground parking lot and going into the main building. After that, we derived the affecting factors for selecting the way of going into the main building. The affecting factors include constructability, convenience, economic efficiency as a high level as well as existence and nonexistence of basement and removal, safety of current building, parking measure of capacity, amenity, inhabitant traffic line, construction expenses and construction duration as a low one. This study will be applied as a reference for selecting the way of going into the main building when constructing an underground parking lot especially targetted on an old apartment house.