• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.3
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• pp.43-51
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• 1997

The nutrients runoff including nitrogen and phosphorous was investigated to find out the characteristics of nutrient discharge from the slurrigated area using digested animal manure. The results obtained are summarized as follows: 1.The concentrations of T-N, $NH_4$- N, EC, T- P and Cl- were high in flood runoff. 2.The concentration of nutrients by the surface runoff, except for $NO_3$-N, showed a tendency of increasing when the period of dry days before the rain fall was long. And the concentration of N$NO_3$-N increased in the inflow section where subsurface drainage flowed in. 3.The quality of water was generally influenced by the discharge of water quantity from slurrigated area. However the runoff concentration influenced the water quality when it was high enough. 4.To reduce loss of the nutrients and improve the fertilization effect, it is not recommended to apply slurry in rainy season.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.7
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• pp.43-50
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• 1995

In this paper, the variational method are used for the filter analysis methods and a CAD program for the design of the waveguide low-loss bandpass filters using inductive window structures for the VSAT(Very Small Aperture Terminal) system has been developed based on the passband correction method combined with fiter synthesis procedures. Using the developed CAD program, 0.01dB equi-ripple chebyshev type 6-section bandpass filters which are sued in the VSAT system operating nationally are designed for the purpose of the Down-link of 12.75~13.25GHz and the Up-link of 14.0~14.5GHz, fabricated and mesured. The measured results are good agreement woth the theoretical resuls.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.174-175
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• 2019

In this study, the spalling and ultrasonic pulse transmission time of concrete were investigated according to compressive strength during heating. As a result, the higher the compressive strength of the concrete, the more the explosion occurs, which affects the cross-sectional loss and the spalling fragment size. Also, ultrasonic pulse transmission time was found to be strongly influenced by the section loss of concrete.

• Journal of the Korean Institute of Telematics and Electronics
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• v.7 no.2
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• pp.43-48
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• 1970

The precise measurement technique for dielectric constent of high-loss nonmagnetic materials is described. This technique use6 is based upon cavity resonance method and impedance method. Dielectric constant can be calculated from simple formulas without using transcen-dental equations. The error contained in x-band yields loss tangent, 3%, and dielertric constant, 1%, for materials filled in cross section of waveguide.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1681-1688
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• 2009

This paper proposes a new fault restoration method which adopts the recloser as top agent to release the problems of the data concentration and fault processing delay of the existing DAS(distribution Automation System) under the ubiquitous distribution system. In proposed method, top agent collects the data based on the multi-casting communication with the tie switches of the interconnection point, and then selects a closed switch(tie switch) to transfer the sound outage load to other feeders based on the heuristic search strategy step by step until the load transfer work is finished. Here, a new heuristic rule is developed which can guarantee the relational load balancing and line loss from the collected voltage data. Finally, the several faults are simulated for typical multi-section and multi-interconnection distribution system to prove the effectiveness of the proposed strategy, in particular, for each simulation cases, the load balancing index and line loss index of the obtained solution from the proposed method is compared with those of all of feasible solutions.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.18-23
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• 1996

This paper proposes a new levitation scheme for EDS MAGLEV vehicle with AC superconducting magnet(ACSCM). The eddy current and the levitation force are generated at all speed including stand still in this scheme, therefore, the auxiliary wheels on DCSCM can be eliminated. To reduce the ac loss of the magnet, the ACSCM also can be operated as a DCASCM at high speed because levitation force generated by DCSCM is enough at high speed. To prove the effectiveness of the proposed scheme, the repulsive force and power loss versus frequency of ACSCM is calculated. For comparison, characteristics of DCSCM of same cross section versus speed are also given. (author). 6 refs., 9 figs.

• Computers and Concrete
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• v.2 no.5
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• pp.367-380
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• 2005

Recent earthquakes have shown that many of existing buildings in Iran sustain heavy damage due to defective seismic details. To assess vulnerability of one common type of buildings, which consists of low rise framed concrete structures, three defective and three standard columns have been tested under reversed cyclic load. The substandard specimens suffered in average 37% loss of strength and 45% loss of energy dissipation capacity relative to standard specimens, and this was mainly due to less lateral and longitudinal reinforcement and insufficient sectional dimensions. A relationship has been developed to introduce variation of plastic length under increasing displacement amplitude. At ultimate state, the length of plastic hinge is almost equal to full depth of section. Using calibrated hysteresis models, the response of different specimens under two earthquakes has been analyzed. The analysis indicated that the ratio between displacement demand and capacity of standard specimens is about unity and that of deficient ones is about 1.7.

• Corrosion Science and Technology
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• v.7 no.1
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• pp.50-60
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• 2008

The majority of the described experimental results deal with relatively pure aluminium. Variations were made in the pretreatment of the aluminum substrates and an investigation was performed on the resulting changes in oxide layer composition and chemistry. Subsequently, the bonding behavior of the surfaces was investigated by using model adhesion molecules. These molecules were chosen to represent the bonding functionality of an organic polymer. They were applied onto the pretreated surfaces as a monolayer and the bonding behavior was studied using infrared reflection absorption spectroscopy. A direct and clear relation was found between the hydroxyl fraction on the oxide surfaces and the amount of molecules that subsequently bonded to the surface. Moreover, it was found that most bonds between the oxide surface and organic functional groups are not stable in the presence of water. The best performance was obtained using molecules, which are capable of chemisorption with the oxide surface. Finally, it was found that freshly prepared relatively pure aluminum substrates, which are left in air, rapidly lose their bonding capacity towards organic functional groups. This can be attributed to the adsorption of contamination and water to the oxide surface. In addition the adhesion of a typical epoxy-coated aluminum system was investigated during exposure to water at different temperatures. The coating was found to quite rapidly lose its adhesion upon exposure to water. This rapid loss of adhesion corresponds well with the data where it was demonstrated that the studied epoxy coating only bonds through physisorptive hydrogen bonding, these bonds not being stable in the presence of water. After the initial loss the adhesion of the coating was however found to recover again and even exceeded the adhesion prior to exposure. The improvement could be ascribed to the growth of a thin oxyhydroxide layer on the aluminum substrate, which forms a new, water-stable and stronger bond with the epoxy coating. Two routes for improvement of adhesion are finally decribed including an interphasial polymeric thin layer and a treatment in boiling water of the substrate before coating takes place. The adhesion properties were finely also studied as a function of the Mg content of the alloys. It was shown that an enrichment of Mg in the oxide could take place when Mg containing alloys are heat-treated. It is expected that for these alloys the (hydr)oxide fraction also depends on the pre-treatment and on the distribution of magnesium as compared to the aluminium hydroxides, with a direct impact on adhesive properties.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.5-8
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• 2001

A three node flat triangular element incorporating Layerwise Zig-Zag Theory(HZZT) is developed suitable for analyzing damped laminated composite structures. Using an interdependent kinematic relation, the higher order shear rotations are replaced by in-plane displacements, a transverse displacement and section rotations, which result in three translations and two rotations. Natural frequencies and modal loss factors of cantilevered laminated plates with embedded damping layers are calculated with the zig-zag triangular element and compared to the experimental results and MSC/NASTRAN results using a layered combination of plate and solid elements.

• ETRI Journal
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• v.30 no.5
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• pp.723-728
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• 2008

In this paper, a simple transmission line model for an edge-coupled patch antenna is presented. The coupled section is modeled with a lump network which represents the mutual admittance between patches and from patch to ground. Theoretical analysis of two edge-coupled patch antenna models are compared by simulation and experiment in antennas designed to operate at the 2 GHz band. The proposed model predicts the return loss of the antenna accurately.