• Journal of Korean Society of Water and Wastewater
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• v.19 no.4
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• pp.473-479
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• 2005

Applying enhanced coagulation is not uncommon not only to improve water quality but also to obtain economical advantages in water treatment. In this study, the economical evaluation was investigated with considering dosage of coagulant, produced sludges and usage of activated carbon with two different water sources. To simulate the granular activated carbon(GAC) adsorber mini-column test was adapted. Even if there were some variation according to the source waters, the life time of GAC was extended 60 to 110days with adding 2.5 to 3 times of coagulant in enhanced coagulation. With assumption of changing GAC adsorber at 50% of breakthrough the total treatment cost can be reduced to range from 25% to 44% with adapting the enhanced coagulation. The obtained value can not be generalized because the value can be varied by water quality and cost of the GAC or coagulant. However, the evaluation can be basis starting point to find optimum operation methods for the drinking water treatment which has plan to adapt GAC adsorber.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1002-1008
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• 2011

Turnout is a mechanical installation enabling railway trains to be guided from one track to another at a railway junction. there are classified variously according to rail type, sleeper type, fastening system, track type. Construction of concrete track are on the increase recently to secure the safety of track structure as well as to reduce the maintenance cost. SFC fastening system used the plain track a lot and for those reasons, The fast clip turnout demand growing to improving efficiency of the maintenance cost by unification of fastening clip on whole line. in this study is about development of the fastening system for new turnout using fast clip. this fastening system assembled elasticity pad underneath a base plate. its can change stiffness how to adjust contact surface area of elasticity pad Developed fastening system have passed test according to rule of KRS-TR0014-09R (rail fastening system) and Performance Certification by KR.

• Journal of Sensor Science and Technology
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• v.22 no.1
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• pp.84-88
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• 2013

In this paper, the low price signal generator with capability of frequency high-resolution and variable sync pulse has implemented. It fulfils well the requirements for SS-OCT of the frequency resolution less than 1Hz, frequency stability of ${\leq}{\pm}0.5Hz$/10 min and variable sync pulse output timing. Through its performance test applied to wavelength swept laser, 120 nm sweeping range and 10 mW average optical power were obtained. This shows that the realized sine-wave generator can replace the commercial high cost and high performance signal generators employed by current SS-OCT systems.

• Journal of Information Technology Services
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• v.12 no.4
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• pp.255-265
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• 2013

This paper proposes a DEA-AR model for the efficiency evaluation of the iron ore brands in an integrated steel mill. The input factor is defined as unit cost of each brand based on CIF and two output factors are chosen as Fe and Al which are the important ingredients of iron ore. The relative importance between two output factors is determined by several experts using AHP model. The efficiency of each brand is determined using DEA and DEA-AR models. The negative correlation between the DEA-AR efficiency and the unit cost (CIF) is shown as significant whereas no significant correlation exist between the efficiency and the output factors. Also, the Kruskal Wallis rank sum test shows that there exist efficiency differences among the iron ore types whereas no difference is shown among the countries. The result could be utilized in selecting good brands of iron ores based on the DEA-AR efficiency in an integrated steel mill.

• Explosives and Blasting
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• v.35 no.2
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• pp.1-8
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• 2017

In this study, the characteristics of a new rock cracking method using steam pressure are briefly presented. The rock cracking method was originally developed as a means to decrease the ground vibrations from underground rock excavations. The validation tests were also conducted by applying the method to an actual rock tunnel under construction. The ground vibrations were measured in the vicinity of the test site. The measured vibration results were compared with the values predicted by an attenuation equation, which had been proposed by a company in Japan. Also, a simple cost assessment for the method was conducted to demonstrate its cost effectiveness in underground tunnel excavations.

• Proceedings of the Society of Korea Industrial and System Engineering Conference
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• 2002.05a
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• pp.209-215
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• 2002

In this paper, we propose a freight and fleet optimization model under CVO environment. The model is a kind of multi commodity network flow model based on Vehicle Routing Problem(VRP) and Vehicle Scheduling Problem(VSP), and considering operations and purposes of CVO. The main purpose of CVO is the freight and fleet management to reduce logistics cost and to Improve in vehicle safety. Thus, the objective of this model is to minimize routing cost of all the vehicle and to find the location of commodities which have origin and destination. We also present some computing test results.

• Journal of Korean Institute of Industrial Engineers
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• v.35 no.1
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• pp.15-39
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• 2009

Advanced planning and scheduling (APS) refers to a manufacturing management process by which raw materials and production capacity are optimally allocated to meet demand. APS is especially well-suited to environments where simpler planning methods cannot adequately address complex trade-offs between competing priorities. However, most scheduling problems of APS in the real world face both inevitable constraints such as due date, capability, transportation cost, set up cost and available resources. In this survey paper, we address three crucial issues in APS, including basic scheduling model, job-shop scheduling (JSP), assembly line balancing (ALB) model, and integrated scheduling models for manufacturing and logistics. Several evolutionary algorithms which adapt to the problems are surveyed and proposed; some test instances based on the practical problems demonstrate the effectiveness and efficiency of evolutionary approaches.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.77-83
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• 1999

Due to the high cost of constructing anechoic chamber, the multi-usage of a chamber in various applications is very effective in terms of cost as well as space. In this paper, we describe an anechoic chamber currently used at SK Telecom in Korea. This is designed for the measurements of both far/near field antenna and EMC/EMI in the identical chamber. This anechoic chamber and measurement system support antenna test in the frequency range of 150 MHz to 40 GHz and meet the requirement of ANSI C63.4 and CISPR 16.1 for EMC/EMI.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.381-388
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• 1999

The existing methods for installation of long steel pipe pile have some uneconomical problems such as increase of installation cost and period due to the welding of two piles and removal of soil plug, and decrease of driving efficiency due to the increase of driving resistance by time effect during the welding of piles and removal of soil plug, etc. Thus, in this study, new installation method for long steel pipe pile is suggested to work out the existing problems, and calibration chamber tests are peformed to investigate both driving and economical efficiency for the suggested method. The test results showed that the new installation method has increase bearing capacity as well as reduce installation cost and period for long steel pipe piles as compared with existing methods.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.171-172
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• 2012

In this study the continuous rectangular spiral hoop is used for saving cost and time, solving manpower shortage, and the quality of structures. Generally the use of continuous spiral reinforcement in reinforced concrete elements improve the strength and the ductility of the concrete. Savings in cost and time is demonstrated with the continuous rectangular spiral hoop through the mock up test of beam and column elements. In case of a 4m column element the time of rebar work decreases up to 40% compared with traditional hoop, and in case of a 8m beam the time also decreases 40%. This study present the construction method and details.