• Nuclear Engineering and Technology
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• v.52 no.7
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• pp.1471-1480
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• 2020

This research presents a case study on the remediation of a radioactive waste (uranium: U) utilizing a multi-objective fuzzy optimization in an electrocoagulation process for the iron-stainless steel and aluminum-stainless steel anode/cathode systems. The incorporation of the cumulative uncertainty of result, operational cost and energy consumption are essential key elements in determining the feasibility of the developed model equations in satisfying specific maximum contaminant level (MCL) required by stringent environmental regulations worldwide. Pareto-optimal solutions showed that the iron system (0 ㎍/L U: 492 USD/g-U) outperformed the aluminum system (96 ㎍/L U: 747 USD/g-U) in terms of the retained uranium concentration and energy consumption. Thus, the iron system was further carried out in a multi-objective analysis due to its feasibility in satisfying various uranium standard regulatory limits. Based on the 30 ㎍/L MCL, the decision-making process via fuzzy logic showed an overall satisfaction of 6.1% at a treatment time and current density of 101.6 min and 59.9 mA/㎠, respectively. The fuzzy optimal solution reveals the following: uranium concentration - 5 ㎍/L, cumulative uncertainty - 25 ㎍/L, energy consumption - 461.7 kWh/g-U and operational cost based on electricity cost in the United States - 60.0 USD/g-U, South Korea - 55.4 USD/g-U and Finland - 78.5 USD/g-U.

• Journal of Korean Society of Steel Construction
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• v.24 no.2
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• pp.199-206
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• 2012

Unstiffened seated connections (USC) ensure easy installation and safety during erection, thereby making the process more economical. USCs consist of a seat angle for carrying the beam's reactions and a top angle to provide beam stability. These angles are bolted or welded to the beam and supporting member. This paper sought to propose a design table for the weld strength of such connections obtained from the elastic vector method (EVM) and the instantaneous center-of-rotation method (ICM) in terms of calculating the eccentricity. Also, the proposed design table is compared with both AISC and KBC specifications.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.145-146
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• 2011

Lifting plan in conjunction with the overall construction plan will be established. It is being created by executive director of the Corporation and other such as an experienced site manager. But, written lifting plan based on the limited information and experience is causing some problems such as decreasing productivity, workability loss, delay. The reasons for the problems are lack of prediction of construction execution, inappropriate materials on the past performance, individual experience, limits of knowledge, lack of technical materials, shortage of advisor. Therefore, to solve the problems, we have to overcome the situation in which we depends on lifting planner's experience and intuition, limited information by accumulating objective and reliable materials. Because unorganized lifting plan will lower efficiency of lifting equipment and make reducing construction period difficult. In this study, influence factors on lifting plans will be derived through reviewing literatures and lifting plan cases. Derived influence factors will be classified as components and classes, classified influence factors are assessed suitability. Also, Decision making items are derived from the factors. Finally, tower crane lifting plan process will be suggested from the result.

• Journal of Environmental Science International
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• v.7 no.3
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• pp.361-368
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• 1998

The structure such as building and cultural properties was composed of various materials like wood, metal and stone that have been utilized and exposed to air, wind and rain far a long time. However, because of their special characteristics as structure, collecting of samples that may involve their destruction cannot be permitted, ever for material analysis. Therefore, h order to study the Influence of atmospheric pollution on structure, atmospheric corrosion tests were achieved by making use of materials(bronze. ancient copper, copper, steel and marble) in field exposure tests. Atmospheric exposure sites are selected from places which are characterized by urban, rural, Industrial and marine enoronments In Northeast Asia. According to the results of atmospheric corrosion tests: The corrosion rates of Industrial states In china were more serious than other sampling sites. In the correlation of meteorological factors. wet hours was defiled as Intogeacted hours under that atmospheric temperature is above $0^{\circ}C$ and relative humidity in above 80% that has a great influence on corrosion tests of materials in case of a short time. The relative humidity was above about 75% that resulted in great increase of corrosion rates. In the esimation of corrosion rates between materials, corrosion rates of steel was about thirty times and decuple larger than that of other materials excluding marble in unshelterd exposure and In sheltered exposure.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.3
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• pp.313-318
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• 1983

It is required in designing a spot welding to get in advance an estimated figure of nugget diameter. A method of estimating nugget diameter of low carbon steel sheets is suggested in tesms of utilizing elastic calculation in theory and of making a sectional observation of specimen of spot welding in experiment. The resultant findings are summarized as follows: 1) A contact diameter of sheet, 2.gamma.$_{o}$=d sub e/+(1.1)t, wheer de is the electrode tip diameter and t is the thickness of sheets. 2) The practical measurement of the nugget diameter reveals that $d_{n}$=(1.05) $d_{e}$+(0.9)t, and $d_{b}$ is less by 0.8-4.3% than 2.gamma.$_{o}$. 3) The more $d_{n}$ is as compared with t, the less the difference between a theoretical value and an experimental value is. 4) In the spot welding of thin steel sheets less than 3mm in thickness that are commonly used in sheet metal works, the contact diameter equals the nugget diameter. In this case, either the theoretical or experimental approach can be used for estimating the nugget diameter.meter.ter.r.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.149-156
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• 2003

Recently, the importance of plant maintenance(PM) was highly raised to provide efficient plant operation which highly affects the productivity. For this reason, a number of engineering methodologies, such as riskbased inspection(RBI), fitness for service guidelines(FFS), plant lifecycle management(PLM), have been applied to improve the plant operation efficiency. Also, a network-based business operation system, which is called ERP(Enterprise Resource Planning), has been introduced in the field of plant maintenance. However, there was no attempt to connect engineering methodologies to the ERP PM system. In this paper, a knowledge-based information system for the plant operation of steel making company has been proposed. This system, which is named as K-VRS(Knowledge-based Virtual Reality System), provides a connection between ERP plant maintenance module and knowledge-based engineering methodologies, and thus, enables network-based highly effective plant maintenance process. The developed system is expected to play a great role for more efficient and safer plant maintenance.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.514-519
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• 2001

Converter has been slag produced 10 million tons per year in Japan. It is a steel making by product produced in the same way as the blast-furnace slag. Though blast-furnace slag is being used effectively as a concrete admixture, the converter stag has never been used effectively because of the expansion action of contained free lime and iron oxide. This is an important environmental problem in the steel industry. Beta-2CaOSiO$_2$(beta-C$_2$S) is contained 40 percent in converter slag, therefore it is very promising as a concrete admixture. We proposed an accelerated aging processes capable of stabilizing the converter slag in a short time. The converter slag is dipped into alkali aqueous solution after heating at low temperature. It was subsequently ground to a grain size of 75 ${\mu}{\textrm}{m}$ , inner 30 percent of OPC. The properties of mortar and concrete using the blended cement were determined. As a result, it has become apparent that the expansion was reduced and long term compressive strength was increased while that at early ages was not so remarkable. The hydration exotherm rate was lower than that of the OPC.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.11
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• pp.1933-1940
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• 2003

Recently, the importance of plant maintenance(PM) was highly raised to provide efficient plant operation which highly affects the productivity. For this reason, a number of engineering methodologies, such as risk-based inspection(RBI), fitness for service guidelines(FFS), plant lifecycle management(PLM), have been applied to improve the plant operation efficiency. Also, a network-based business operation system, which is called ERP(Enterprise Resource Planning), has been introduced in the field of plant maintenance. However, there was no attempt to connect engineering methodologies to the ERP PM system. In this paper, a knowledge-based information system for the plant operation of steel making company has been proposed. This system which is named as K-VRS(Knowledge-based Virtual Reality System), provides a connection between ERP plant maintenance module and knowledge-based engineering methodologies, and thus, enables network-based highly effective plant maintenance process. The developed system is expected to play a great role for more efficient and safer plant maintenance.

• Journal of the Korean Society for Heat Treatment
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• v.25 no.4
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• pp.181-189
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• 2012

The demand on quantitative measurement of the heat flux is motivated in making higher-quality steel product through a water quenching process of plate mill. To improve a spatial degree of heat flux measurement, the multi-point heat flux measurement was carried out by a unique experimental technique that has a combination of the existing single-point heat flux gauge. The corresponding heat flux can be easily determined by Fourier's law in a conventional way. The multi-point heat flux gauge developed in this study can be applicable to measure the surface heat flux, the surface heat transfer coefficient during a water quenching applications of steelmaking process. The results exhibit different heat transfer regimes; such as single-phase forced convection, nucleate boiling, and film boiling, that are occurred in close proximity on the multi-point heat flux gauge quenched by water impinging jet.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.6
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• pp.64-76
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• 1997

This paper deals with development of brackets by using aluminum alloy sheets which is indispensable for weight reduction of autobody. The press formability of aluminum alloy sheet is estimated by means of tensile test, V bending test, sample manufacturing test and photograph of microstructure. The results show that the elongation, strength, work hardening exponent, plastic anisotropy coefficient of Al 6***series are better than those of Al 5***series, but for general press formability, Al 5***series are better than Al 6***series due to lower yield strength. Since most of mechanical properties of aluminum sheet are generally inferior to those of cold-rolled steel sheet, shape fixability and press formability of aluminum sheet are very poor. For making components of autobody by use of die for steel sheet application, it is essential that die should be nodified for least bending and stretching. With the modified die for aluminum, it could be possible to make brackets, the component of autobody. Microstructure of Al 5***series has fine grain and small the 2nd phase and that of Al 6***series has relatively coarse grain. Therefore, it seems that fine grain and small the 2nd phase of Al 5***series is one of the factor of lower yield strength, resistance to stamping work, formation of Luder's line.