• Wind and Structures
• /
• v.7 no.4
• /
• pp.235-250
• /
• 2004

The current study reports the results of an experimental program conducted on a structure fitted with a liquid damper (TLD) and subjected to harmonic excitation. Screens were placed inside the TLD to achieve the required inherent damping. In the first part of the study, reduced scale models of the building-TLD systems were tested under two levels of excitation. The efficiency of the damper was assessed by evaluating the effective damping provided to the structure and comparing it to the optimum effective damping value, provided by a linear tuned mass damper (TMD). An extensive parametric study was then conducted for one of the three models by varying both the excitation amplitude and the tuning ratio, defined as the ratio of the TLD sloshing frequency to the natural frequency of the structure. The effectiveness and robustness of a TLD with screens were assessed. Results indicate that the TLD can be tuned to achieve a robust performance and that its efficiency is not significantly affected by the level of excitation. Finally, the equivalent amplitude dependent TMD model, developed in the companion paper is validated using the system test results.

• Korean Journal of Materials Research
• /
• v.13 no.3
• /
• pp.191-194
• /
• 2003

The influence of on ion beam irradiation to the indium tin oxide (ITO) substrate on the performance of the organic light-emitting diodes (OLEDs) was studied. ITO films were used as the transparent anode of OLEDs with poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) as a hole-injection/transport layer. Oxygen and argon plasma treatment of ITO resulted in a change in the work function and the chemical composition. For plasma treated ITO anodes, the device efficiency clearly correlated with the value of the work function. We also discussed the implications of our experimental study in relation to the modification of the ITO surface composition, transmittance, reflectance, and water contact angle (WCA).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.9
• /
• pp.908-914
• /
• 2013

A shaped Cassegrain antenna is designed from the condition of the same path length at the equi-phase surface by using the conservation of energy and Snell's law. In order to improve the phase error efficiency of aperture surface, the surface profile of the main and sub-reflectors is found to satisfy the power distribution and the equi-phase condition at the aperture surface. The sidelobe levels of 36.4 dB and 33.9 dB are achieved at the AZ and EL planes, respectively from numerical calculation by physical optics method at Ku band and the directivity of designed antenna is 10 percent greater than that of conventional antenna.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1998.06a
• /
• pp.391-394
• /
• 1998

Electroluminescence is the light emission obtained by an electrical excitation energy passing through a phosphor under an applied high electrical field. EL are paid much attention on flat panel display as a backlight and indicator, which are divided into ACPRL(alternating-current powder electroluminescent) and ACTFEL(alternating-current powder electroluminescent). In this paper, Electric and emission properties on ACPEL are investigated based on ZnS:Cu phosphor. The basic structure on this is ITO glass/phosphor/insulator/ backelectrode, CR-M which has high efficiency on thermal properties and dielectric Properties was introduced and BaTiO$_3$ as a insulating layer in order to increase app1ied electric field on phosphor. Changing on Dielectric and emission Properties was caused by a different viscosity of binder which filled on space between phosphor particle. 60cd/$m^2$ under 60V, 2kHz sinusoidal was gotten from ACPELD prepared in this work.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.1705-1707
• /
• 2000

유기 전기발광 디스플레이 (Electroluminescence Display; ELD)는 저전압 구동, 자기발광, 경량박형, 광시야각, 빠른 응답속도 등의 장점으로 차세대 디스플레이의 후보로서 주목받고 있다. Eu complex는 610 nm 부근에서 예리한 스펙트럼의 대역폭을 가지며 붉은색의 강한 형광을 나타내는 유기화합물로 잘 알려져, 있다. 새로이 합성한 란탄계 금속착물인 $Eu(TTA)_{3}TPPO$를 발광층으로 사용하여 적색 발광의 효율을 높이기 위해 소자를 제작하였고, 이 때 구동 전압은 9 V이고 18 V에서 가장 밝은 38cd/$m^2$의 휘도를 나타내었으며 전류밀도는 20mA/$cm^2$ 이었다. 제작된 소자의 EL 스펙트럼은 615 nm로 PL 스펙트럼과 동일하게 예리한 최대 피크를 나타내었고, 순환 전압전류법을 이용하여 각 유기 물질들의 에너지 준위를 알 수 있었으며, 각각의 소자들의 에너지 밴드 다이어그램을 통하여 전기적 특성을 분석하였다.

• Journal of the Korean Chemical Society
• /
• v.57 no.2
• /
• pp.272-278
• /
• 2013

Extract of ginger has been evaluated as a green inhibitor for the corrosion of steel in sulfide polluted NaCl solution using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Potentiodynamic polarization measurements showed that this extract acts as a mixed type inhibitor but mainly inhibits the cathodic reaction. The inhibition efficiency was found to increase with inhibitor concentration reaching to approximately 83.9% using 250 ppm of ginger. Nyquist plots show a single capacitive loop in uninhibited and inhibited solutions. From EFM the causality factors are very close to theoretical values which indicate that the measured data are of good quality. The adsorption process of the studied extract on steel surface obeys Temkin adsorption isotherm. The results obtained from the different electrochemical techniques were in good agreement which prove the validity of these tools in measurement of corrosion rate. Ginger extract has no effect on Escherichia Coli and can be applied safely on waste water treatment plants.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.12
• /
• pp.5895-5901
• /
• 2011

This paper shows that a scheme provided by An[7] is not enough to satisfy security requirements for a user certification using a password-based smart card. In order to compensate this weakness, this study provides an improved user scheme with a hash function and ElGamal signature. This new scheme has some advantages protecting password guessing attack, masquerade, and replay attack as well as providing forward secrecy. Compared to An's certification scheme, this scheme suggests that the effect of computational complexity is similar but the efficiency of safety is better.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.5
• /
• pp.2574-2587
• /
• 2019

Blind Source Separation (BSS) is a technique used to separate supposed independent sources of signals from a given set of observations. In this paper, the High Exploration Particle Swarm Optimization (HEPSO) algorithm, which is an enhancement of the Particle Swarm Optimization (PSO) algorithm, has been used to separate a set of source signals. Compared to PSO algorithm, HEPSO algorithm depends on two additional operators. The first operator is based on the multi-crossover mechanism of the genetic algorithm while the second one relies on the bee colony mechanism. Both operators have been employed to update the velocity and the position of the particles respectively. Thus, they are used to find the optimal separating matrix. The proposed method enhances the overall efficiency of the standard PSO in terms of good exploration and performance. Based on many tests realized on speech and music signals supplied by the BSS demo, experimental results confirm the robustness and the accuracy of the introduced BSS technique.

• Journal of Electrochemical Science and Technology
• /
• v.9 no.4
• /
• pp.260-275
• /
• 2018

The corrosion inhibition of cast iron in 1 M HCl by Phenanthroline (Phen) was investigated using potentiodynamic polarization (PDP) curves, electrochemical impedance spectroscopy (EIS), surface analysis and theoretical calculations. It is found that Phen exhibits high inhibition activity towards the corrosive action of HCl and its adsorption obeys the Langmuir adsorption isotherm model. The results showed that inhibition efficiency increases with Phen concentration up to a maximum value of 96% at 1.4 mM, and decreases slightly with the increase in temperature. The free adsorption energy value indicates that Phen adsorbs on cast iron surface in 1 M HCl via a simultaneous physisorption and chemisorption mechanism. Scanning electron microscopy (SEM) micrographs, atomic force microscopy (AFM) and FTIR analysis confirmed the formation of a protective film on cast iron surface, resulting in the improvement of its corrosion resistance in the studied aggressive solution. Quantum chemical calculations at the DFT level were achieved to correlate electronic structure parameters of Phen molecules with their adsorption mode.

• Nuclear Engineering and Technology
• /
• v.53 no.4
• /
• pp.1079-1087
• /
• 2021

NTP-ERSN is a package developed for solving the multigroup form of the discrete ordinates, characteristics and collision probability of the Boltzmann transport equation in one-dimensional cartesian geometry, by combining pin cells. In this work, C5G7 MOX benchmark is used to verify the accuracy and efficiency of NTP-ERSN package, by treating reactor core problems without spatial homogenization. This benchmark requires solutions in the form of normalized pin powers as well as the vectors and the eigenvalue. All NTP-ERSN simulations are carried out with appropriate spatial and angular approximations. A good agreement between NTP-ERSN results with those obtained with OpenMC calculation code for seven energy groups. In addition, our studies about angular and mesh refinements are carried out to produce better quality solution. Moreover, NTP-ERSN GUI has also been updated and adapted to python 3 programming language.