• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.263-268
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• 1997

One of the principal causes of the deterioation of coastal concrete structures is the corrosion of reinforcing steel induced by the attack of chloride ions. An experimental study was performed to investigate the distribution of concentration of chloride ions in a coastal concrete structure and to measure the half-cell potential of embedded steel by using the copper-copper sulfate reference electrode. Quantitative analysis showed that the concentration of chloride ion in the aqueous phase near the surface of embedded steel exceeded a threshold value for corrosion, 0.05% by weight in concrete. The absolute value of half-cell potential at some members of embedded steel was measured to be higher than 350mV, indicating that the probability of corrosion is more than 90%. The prediction on corrosion based on the experimental measurements was confirmed by the observation of corrosion on the surface of steel bars in the concrete core taken out of the concrete structure.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2008.04a
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• pp.255-258
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• 2008

For rapidly increasing amount of medical images, it is difficult for radiologist to interpretate the medical images fastly and for sufficient time. We investigated whether liver CT image has good features to be analyzed by computer algorithm, We examed the CT images of liver tumors (Hepetocellular carcinomas; HCCs) and searched any potential morphologic characteristics to be analyzed by computer algorithms. On unenhanced CT, HCCs appeared hypodense After enhancement, most HCCs were hyperdense, and then. as a consequence of rapid washout, HCCS became hypodense compared with the liver parenchyma. Most CT images of HCCs showed synchronous phase-specific.morphologic features. We applied various edge detection filters to these images and some filters showed favorable performance in the detection of tile edge of liver and HCC. Therefore, theses features seems to be analyzed by computer algorithms effectively.Further studies may be warranted.

• Journal of Korean Society for Quality Management
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• v.13 no.1
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• pp.26-30
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• 1985

In the light of the properties of colloids, in the surface of disperse phase and dispersion, there exist specific characters such as adsorption or electric double layer, which seems to play important roles in determining the physiochemical properties in the dyeing system. Nylon, wool and silk, the typical amphoteric fibers were dyed with Acid dye and various combinations were prepared by combining pH, temperature and dye concentration, in order to generate flowing electric potential which were measured by microviolt meter and specific conductivity meter. The results were transformed to Zeta potential by Helmholtz-Smoluchowski formular and to surface electric charge density by Suzawa formular, surface dye amount, and effective surface area of fibers, and these data were statistically analysed by principle component analysis.

• Journal of Construction Engineering and Project Management
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• v.5 no.1
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• pp.20-25
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• 2015

Interface management problems inherent in construction projects hamper their successful delivery. Therefore, this study aimed at determining the most important project interfaces in construction works in Nigeria in terms of most significant potential impacts, so that management attention are objectively focused on potential highest impacting project interfaces. From a review of literature, 28 project interfaces management issues were identified and categorized. Structured questionnaires were used to collect data concerning the impact (estimated losses to the project in terms of cost) and probability of occurrence of the identified interfaces. The interfaces were ranked using their computed Matrix Scores (MS). The results reveal that "project-workers interfaces problem manifested in use of inappropriate mixes" is the highest impacting. A ranking of the interface categories also reveal that the interfaces at the execution phase of a project (MS = 1226.79) are those that could result in the highest losses to the project.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.10
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• pp.457-464
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• 2005

Both ratio error and phase angle error in potential transformer(PT) are critically affected by used burden, connected in parallel to the secondary terminal of the PT. Thus precise measurement of burden value is very important for the evaluation of PT An automatic measurement system has been developed for the measurement of burden value and power factor of a burden. The ac voltage, current and power of the burden are measured precisely, and the burden value and power factor were calculated from these measured values. The resistance and inductance values of the tested burden are also calculated. The overall measurement uncertainties are calculated and reported with the burden value and power factor. The best measurement uncertainty for the burden measurement with the developed automatic measurement system was estimated to be 0.5 $\%$.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1659-1662
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• 1998

This paper is to analyze electromagnetic fields on a 154kV substation system and induced voltages on the substation fence when the network is operating in a normal condition or a fault condition in which one phase is shorted with the overhead ground wire. Also, changing the scalar potential and electromagnetic fields that are changed in accordance with changing resistivity and permeability of ground are studied. A finding of the study is that the scalar potential and electromagnetic fields are raised near the tower: The values of electric field on the corner of fence and at the edge of the ground grid are higher than other locations.

• Bulletin of the Korean Chemical Society
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• v.35 no.10
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• pp.2911-2916
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• 2014

The gas phase structures, energetics, and interconversion pathways of five lowest energy conformers of acetylcholine were examined employing the B3LYP, MP2, and CCSD(T) methods in conjunction with diverse basis sets including the correlation consistent aug-cc-pVDZ and aug-cc-pVTZ basis sets. It is found that use of adequate basis set containing proper polarization and diffuse functions capable of describing the floppy potential energy surface of acetylcholine is important in correctly predicting the relative stability of these conformers. The interconversion pathways and barrier heights between these conformers were elucidated by examining the potential energy surface for torsional motion, which also manifested the presence of chiral conformations of acetylcholine corresponding to the original conformations. On the basis of high level electronic energy calculations and thermal contribution analysis, four lowest energy conformers appear to be populated in the energy range of less than 1 kcal/mol at room temperature.

• Carbon letters
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• v.13 no.1
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• pp.17-22
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• 2012

Currently, graphene is a topic of very active research in fields from science to potential applications. For various radio-frequency (RF) circuit applications including low-noise amplifiers, the unique ambipolar nature of graphene field-effect transistors can be utilized for high-performance frequency multipliers, mixers and high-speed radiometers. Potential integration of graphene on Silicon substrates with complementary metal-oxide-semiconductor compatibility would also benefit future RF systems. The future success of the RF circuit applications depends on vertical and lateral scaling of graphene metal-oxide-semiconductor field-effect transistors to minimize parasitics and improve gate modulation efficiency in the channel. In this paper, we highlight recent progress in graphene materials, devices, and circuits for RF applications. For passive RF applications, we show its transparent electromagnetic shielding in Ku-band and transparent antenna, where its success depends on quality of materials. We also attempt to discuss future applications and challenges of graphene.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.4
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• pp.162-167
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• 2008

FMEA (failure mode and effect analysis)is a widely used technique to assess or to improve reliability of product not only at early stage of design and development, but at the process and service phase during the product life cycle. In designing a service system, this study proposes a fuzzy service FMEA with the service blueprints as a tool which describes customer actions, onstage contact employees actions, backstage contact employees actions, support processes, and physical evidences, in order to analyse and inform service delivery system design. We fuzzified only two risk factors, occurrence and severity, to more effectively assess the potential failure modes in service. Proposed fuzzy risk grades are applied to Gaussian membership function, defuzzified into Fuzzy Inference System, and eventually identified the ranks on the potential fail points.

• Advances in nano research
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• v.1 no.3
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• pp.171-182
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• 2013

The alternating current (AC) conductivity in semiconductor crystals with an open-core screw dislocation is studied in the current work. The screw dislocation in crystalline media results in an effective potential field which affects the electronic transport properties of the system. Therefore, from a technological view point, it is interesting to investigate properties of AC conductivity at frequencies of a few terahertz. To quantify the screw-induced potential effect, we calculated the AC conductivity of dislocated crystals using the Kubo formula. The conductivity showed peaks within the terahertz frequency region, where the amplitude of the AC conductivity was large enough to be measured in experiments. The measurable conductivity peaks did not arise in dislocation-free crystals threaded by a magnetic flux tube. These results imply different conductivity mechanisms in crystals with a screw dislocation than those threaded by a magnetic flux tube, despite the apparent similarity in their electronic eigenstates.