• Korean Journal of Materials Research
• /
• v.3 no.6
• /
• pp.598-605
• /
• 1993

Methacryloxyethyl dimethyl alkyl($C_{1}\sim C_{12}$, benzyl and 2, 2-diethoxy ethyl) ammonium bromide monomers were prepared to investigate the relative humidity characteristics for polymer electrolytes with different chemical structures. They were coated on the alumna substrate printed comblike gold electrode by photopolymerization after micro-syringe injection. As the thickness of rhe humid membrane increased, the impendance decreased, whereas the impedance ~ncreased as the carbon cham of alkyl substituent in the monomer increased. The impendance of the polymeric electrolytes with $C_6\sim C_8$ substituents were varied from 19M$\Omega$ to 5K$\Omega$ for the range of 30-90% Mi. The temperature depedence coefficient in the range of 15-$35^{\circ}C$ was found to be -0.45% $RH/^{\circ}C$and the hysteresis falled within the range of $\pm$2% RH. The response time was 35 second for varying humldity from 33% to 85% RH.

• Steel and Composite Structures
• /
• v.21 no.2
• /
• pp.343-356
• /
• 2016

As the common cast-in-place construction works fails to meet the enormous construction demand under rapid economic growth, the development of prefabricated structure instead becomes increasingly promising in China. For the prefabricated structure, its load carrying connection joint play a key role in maintaining the structural integrity. Therefore, a novel end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and high-strength reinforcement-confined concrete column was proposed. Under action of low cycle repeated horizontal loadings, comparative tests are conducted on 6 prefabricated pre-stressed intermediate joint specimens and 1 cast-in-place joint specimen to obtain the specimen failure modes, hysteresis curves, skeleton curves, ductility factor, stiffness degradation and energy dissipation capacity and other seismic indicators, and the seismic characteristics of the new-type prefabricated beam-column connecting joint are determined. The test results show that all the specimens for end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and high-strength reinforcement-confined concrete column have realized the design objectives of strong column weak beam. The hysteretic curves for specimens are good, indicating desirable ductility and energy dissipation capacity and seismic performances, and the research results provide theoretical basis and technical support for the promotion and application of prefabricated assembly frames in the earthquake zone.

• Smart Structures and Systems
• /
• v.20 no.1
• /
• pp.85-97
• /
• 2017

The aim of this research is to develop a new method to use magnetorheological (MR) damper for vibration control. It is a new way to achieve the MR damper response without the need to have detailed constant parameters estimations. The methodology adopted in designing the control structure in this work is based on the experimental results. In order to investigate and understand the behaviour of an MR damper, an experiment is first conducted. Force-displacement and force-velocity responses with varying current have been established to model the MR damper. The force for upward and downward motions of the damper piston is found to be increasing with current and velocity. In cyclic motion, which is the combination of upward and downward motions of the piston, the force with hysteresis behaviour is seen to be increasing with current. In addition, the energy dissipated is also found to be linear with current. A proportional-integral-derivative (PID) controller, based on the established characteristics for a quarter car suspension model, has been adapted in this study. A fuzzy rule based PID controller (F-PID) is opted to achieve better response for a varying frequency input. The outcome of this study can be used in the modelling of MR damper and applied to control engineering. Moreover, the identified behaviour can help in further development of the MR damper technology.

• Applied Biological Chemistry
• /
• v.33 no.4
• /
• pp.301-306
• /
• 1990

The Physical and chemical properties or dry acorn starch(DS), detannined acorn starch (DTS) and defatted and detannined acorn starch(Drn) were investigated. Ail acorn starch sample, observed by a scanning electron microscope, showed a hemispherical shape ud its size was about $5{\sim}10{\mu}m$ in diameter. It had a little change on the pasting temperature of DS, DTS and DFTS but peak viscosity of DTS was somewhat higher than that of n. Flow behavior of gelatinized starch pastes showed a pseudoplastic behavior and flow behavior index was lower than unit. The consistency coefficient showed concentraion and temperature dependency. The activation energies of DS, DTS and DFTS were $2.09{\sim}3.58Kcal/g\;{\cdot}\;mol and time dependent characteristic of acorn starch samples showed thixotrpic behavior.

• Journal of Sensor Science and Technology
• /
• v.16 no.1
• /
• pp.24-32
• /
• 2007

Conductive rubber material was molded in a belt shape to measure respiration. Its resistivity was approximately $0.03{\;}{\Omega}m$ and the resistance-displacement relationship showed a negative exponent. The temperature coefficient was approximately $0.006{\;}k{\Omega}/^{\circ}C$ negligible when practically applied on the abdomen. The conductive rubber belt was applied on a normal male's abdomen with the dimensional change measured during resting breathing. The abdominal signal was differentiated ($F_{m}$) and compared with the accurate standard air flow rate signal ($F_{s}$) obtained by pneumotachometry. $F_{m}$ and $F_{s}$ differed in waveform, but the start and end timings of each breaths were clearly synchronized, demonstrating that the respiratory frequency could be accurately estimated before further processing of $F_{m}$. $F_{m}-F_{s}$ loop showed a nonlinear hysteresis within each breath period, thus 6 piecewise linear approximation was performed, leading to a mean relative error of 14 %. This error level was relatively large for clinical application, though customized calibration seemed feasible for monitoring general variation of ventilation. The present technique would be of convenient and practical application as a new wearable respiratory transducer.

• Journal of Sericultural and Entomological Science
• /
• v.29 no.2
• /
• pp.58-66
• /
• 1987

This study was investigated on the effect of degumming of cocoon shell, raw silk yarn and grey silk crepe by use of Papain, comparing with soap, soda and soap-soda. The obtained results may be summarized as follows : 1. Degumming loss, when the pretreatment was done, was completed by Papain more than by alkali. 2. Lousiness result of Papain degummed silk yarn was apt to be improved more than that of alkali degummed one. 3. As a result of tensile property test, elasticity and resilience of Papain degummed crepe were good compared to those of alkali degummed one. 4. Not only bending rigidity of Papain degummed crepe was reduced more than that of alkali degummed one but also hysteresis of bending moment was decreased in papain degummed crepe. 5. Handle of Papain degummed crepe was superior to that of alkali degummed one.

• Journal of Korean Society of Steel Construction
• /
• v.22 no.6
• /
• pp.543-551
• /
• 2010

The end-reinforced composite-beam (eco-girder) system was developed that has characteristics of the existing composite beams such as reduced floor height and increased strength. With it, less use of steel is expected. In the eco-girder system, only both ends of the steel-frame beam, which are vulnerable to the ultimate moment, are reinforced with steel plates so that the steel frame beam design will be based on the moment at the beam center. This study used fiber element analysis, which is a simple representation and numerical integration of the principles of the detailed Finite Element Method(FEM), to predict the hysteretic behavior of reinforced composite beams under cyclic loading. The validity of the numerical method was verified by comparing the results of this study with those of previous studies. In addition, the hysteretic behavior of the eco-girder was compared with that of the existing composite beams.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.8
• /
• pp.1080-1089
• /
• 2013

Interior Permanent Magnet Synchronous Machines (IPMSMs) with rare earth magnet are widely used in electric vehicles and hybrid electric vehicles. IPMSMs having high efficiency, high torque, and a wide speed range are employed in propulsion system. And the rotor in an IPMSM is generally made of a rare earth magnet to achieve a large energy product and high torque. This paper discusses issues regarding design and performance of IPMSMs using different factors of BH magnetic characteristic. It is necessary to choose factors of magnetic material according to permanent magnet shape in rotor for high performance. Response Surface Methodology (RSM) is selected to obtain factors of magnetic material according to variety of rotor shapes. The RSM is a collection of mathematical and statistical techniques useful for the analysis of problems in which a response of interest in influenced by several variables and the objective is to optimize response. Therefore, it is necessary to analyze the torque characteristics of an IPMSM having magnet BH hysteresis curve with different rotor shape. Factors of residual flux density (Br) factor and intrinsic coercive force (Hc) are important parameters in RSM for rotor shape. The rotor shapes for IPMSMs having magnet BH characteristic were investigated using the RSM, and three shapes were analyzed in detail using FEA. The results lead to design consequence of IPMSMs in the various rare earth magnet materials.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.12
• /
• pp.2708-2715
• /
• 2012

This paper proposes a new sensorless speed control scheme of induction motor using Model Reference Adaptive Control and Direct Torque Control System. The Model Reference Adaptive Control System is based on the comparison between the outputs of Reference Model and Adjustable Model. The error between the estimated quantities obtained by the two models is used to drive a suitable adaptation mechanism which generates the estimated rotor speed for the Adjustable Model. And the Direct Torque Control scheme controls torque and flux by restricting the flux and torque errors within respective hysteresis bands, and motor torque and flux are controlled by the stator voltage space vector using optimum inverter switching table. The simulation results of proposed method indicate good speed responses from the low speed range to the high, and also show favorable characteristics of load operation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.45-49
• /
• 2001

We have investigated physical and electrical properties of the Hf $O_2$/HfS $i_{x}$/ $O_{y}$ thin film for alternative gate dielectrics in the metal-oxide-semiconductor device. The oxidation of Hf deposited directly on the Si substrate results in the H $f_{x}$/ $O_{y}$ interfacial layer and the high-k Hf $O_2$film simultaneously. Interestingly, the post-oxidation N2 annealing of the H102/H1Si70y thin films reduces(increases) the thickness of an amorphous HfS $i_{x}$/ $O_{y}$ layer(Hf $O_2$ layer). This phenomenon causes the increase of the effective dielectric constant, while maintaining the excellent interfacial properties. The hysteresis window in C-V curves and the midgap interface state density( $D_{itm}$) of Hf $O_2$/HfS $i_{x}$/ $O_{y}$ thin films less than 10 mV and ~3$\times$10$^{11}$ c $m^{-2}$ -eV without post-metallization annealing, respectively. The leakage current was also low (1$\times$10-s A/c $m^2$ at $V_{g}$ = +2 V). It is believed that these excellent results were obtained due to existence of the amorphous HfS $i_{x}$/ $O_{y}$ buffer layer. We also investigated the charge trapping characteristics using Fowler-Nordheim electron injection: We found that the degradation of Hf $O_2$/HfS $i_{x}$/ $O_{y}$ gate oxides is more severe when electrons were injected from the gate electrode.e electrode.e.e electrode.e.