• Journal of the Korea Institute of Building Construction
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• v.19 no.1
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• pp.1-7
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• 2019

This study evaluated the mechanical properties of the alpha-calcium sulfate hemihydrate replaced concrete to reduce the cracking in a box culvert power transmission. After setting the replacement ratio of alpha-calcium sulfate hemihydrate at 0, 6, 9, 12, and 15%, the setting time, compressive strength, and drying shrinkage were measured and the microstructure and crystal structure were analyzed. As a result, it was confirmed that as the replacement ratio of alpha-calcium sulfate hemihydrate increased, the setting time decreased and the compressive strength declined. On the other hand, when the alpha-calcium sulfate hemihydrate was set with 15% of replacement ratio, about 60% reduction in the drying shrinkage was shown compared to that of ordinary Portland cement. Therefore, it is thought that when the concrete replacing the alpha-calcium sulfate hemihydrate is applied to a box culvert power transmission, the cracking reduction performance will be improved, and the improvement of compressive strength will be required.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.239-240
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• 1998

DTET(Dual Transcutaneous Energy Transmission System) is the stable power transferring unit for TAH(Total Artificial Heart) which uses more power than any other artificial organ. It has better efficiency and safety than an ordinary single TET. By reducing the load, it can reduce the change of supplying current for each single TET and it causes the lower change of efficiency. The increment of magnetic flux in coils enables delivering power through thick skin. It can enable internal batteries remove when will be used in a failure of TET, for a lithium ion battery has heavier weight than TET. A DTET should be studied the effect between each coils that generate magnetic flux. It should be compared the advantage with the weakness when it is used.

• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1456-1463
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• 2022

The aim of this work is to study the radiation shielding properties of cement samples with waste glass incortated into its composition. The mass attenuation coefficient (MAC) of the samples were experimentally determined to evaluate their radiation shielding ability. The experimental coefficient was evaluated using NaI detector for gamma energies between 59.53 keV and 1408.01 keV using different radioactive point sources Am-241, Eu-152, Co-60, and Cs-137, and the gamma transmission parameters half-value layer, mean free path, and transmission factor were calculated. The theoretical coefficient of the composites was determined using Geant4 and XCOM software. The results were also compared against Geant4 and XCOM simulations by calculating the relative deviation between the values to determine the accuracy of the results. In addition the mechanical properties (including Compressive and porosity) as well as the thermogravimetric analysis were tested for the present samples. Overall, it was concluded that the cement sample with 50% waste glass has the greatest shielding potential for radiation shielding applications and is a useful way to reuse waste glass.

• International Journal of Contents
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• v.9 no.1
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• pp.26-32
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• 2013

To date, parking enforcement systems have only been used by parking enforcement authorities, who detect and penalize violators. This paper introduces a modified version of the parking enforcement system utilizing smartphones that allows ordinary citizens to report parking violators to parking enforcement officers. The procedures of the system are taking a picture of a vehicle in violation, receiving the violation report virtually and finally reporting if violation car still remained at same location after five minutes have passed. The proposed system contains properties for transmission and receiving data about whether the complaint report of the violator's vehicle has been received in real time. It also works in conjunction with the existing parking enforcement system. This paper describes implementation of the proposed system.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.195-201
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• 1989

Voltage collapse is a serious concern to the electirc utility industry. It is common to associate steady-state stability with the ability of the transmission system to transport real power and to associate voltage collapse with the inability to provide reactive power at the necessary locations within the system. An algorithm to directly calculate the critical point of system voltage collapse was presented by the authors. The method (based on the ordinary power flow equations and explicit requirement of singularity of the Jacobian matrix) is basically one degree of freedom with proper load distribution factors. This paper suggests a modified algorithm to increase the degree of freedom, introducing the nonlinear programming technique. The objective function is a distance measure between the present operating point and the closest voltage collapse point. Knowledge of the distance and the most vulnarable bus from the voltage collapse point of view may be used as a useful index for the secure system operation.

• Journal of Magnetics
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• v.14 no.2
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• pp.97-100
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• 2009

A new eddy current testing probe was developed to separate the eddy current signal distortion caused by permeability variation clusters and ordinary defects created in steam generator tubes. Signal processing circuits were inserted into the probe to increase the signal-to-noise ratio and allow digital signal transmission. The new probe could measure and separate the magnetic phases created in the steam generator tubes in the operating environment of a nuclear power plant. Furthermore, the new eddy current testing probe can measure the defects in steam generator tubes as rapidly as a bobbin probe with enhanced testing speed and reliability of defect detection.

• Journal of the Korea Safety Management & Science
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• v.12 no.3
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• pp.295-302
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• 2010

Nowadays, due to the development of computers and the information and communication technology, data processing and transmission is made very vastly and fast. The development of the technologies bring many changes and revolutions to the life of ordinary people. Although, e-Business grows continuously, it is in experimental stage in domestic area because of limits of infrastructure. Also, in spite of explosive growth of internet, the research on the internet has not been fully studied yet. The objectives of this study are that how service consumers perceive the flow of e-Business, and that what effect the makes on their satisfaction and re-purchase intention. This means that the research enables a marketing manager to take the meaning of comparative weight among the components of e-Business flow, and to provide very useful information to establish marketing strategies which are close to the consumers.

• Structural Engineering and Mechanics
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• v.8 no.3
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• pp.243-256
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• 1999

Using appropriate transformations, the differential equation for flexural free vibration of a cantilever bar with variably distributed mass and stiffness is reduced to a Bessel's equation or an ordinary differential equation with constant coefficients by selecting suitable expressions, such as power functions and exponential functions, for the distributions of stiffness and mass. The general solutions for flexural free vibration of one-step bar with variable cross-section are derived and used to obtain the frequency equation of multi-step cantilever bars. The new exact approach is presented which combines the transfer matrix method and closed form solutions of one step bars. Two numerical examples demonstrate that the calculated natural frequencies and mode shapes of a 27-storey building and a television transmission tower are in good agreement with the corresponding experimental data. It is also shown through the numerical examples that the selected expressions are suitable for describing the distributions of stiffness and mass of typical tall buildings and high-rise structures.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.347-350
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• 2006

The conception of early streamers is in sufficient and inadequate as a parameter for the determination of any advantage of early streamer emission(ESE) lightning rods versus ordinary lightning rods. Thus, standards for many other national and international lightning protection as well as KS C IEC 61024-1 do not take ESE lightning rods, charge dissipation systems or non-conventional lightning rods. Unfortunately, many non-conventional lightning rods such as ESE lightning rods and charge dissipation systems in Korea are increasingly used in lightning protection of structures including explosive manufacturing buildings, electric generating, transmission and distribution systems. This study attempts to make aware of no advantage of ESE rods and other non-conventional lightning protection systems and to investigate the present status of installations of ESE lightning rods.

• Nuclear Engineering and Technology
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• v.50 no.7
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• pp.1106-1111
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• 2018

Electromagnetic waves potentially have been used to heat overdense nuclear fusion plasmas through a double mode conversion from ordinary to slow extraordinary and finally to Electron Bernstein Wave (EBW) modes, OSXB. This scheme is efficient and has not any plasma density limit of electron cyclotron resonance heating due to cut-off layer. The efficiency of conversion depends on the isotropic launching angles of the microwaves with the plasma parameters. In this article, a two-step mode conversions of OSXB power transmission efficiency affected by the fast extraordinary (FX) loses at upper hybrid frequency are studied. In addition, the kinetic (hot) dispersion relation of a overdense plasma in a full wave analysis of a OSXB in Wendelstein 7X (W7-X) stellarator plasma has been numerically simulated. The influence of plasma dependent parameters such as finite Larmor radius, electron thermal velocity and electron cyclotron frequency are represented.