• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.10
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• pp.895-906
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• 2015

This paper presents a methodology and a model that can analyze the high frequency transfer characteristics from socket in the AC power port to the 5 V DC output port in the mobile charging circuit. This is to predict the output signals coming from the IEC(International Electrotechnical Commission) Standard(IEC 61000-4-4), EFT/B(Electric Fast Transient and Burst) immunity test for mobile charging circuit. Since the mobile charging circuit is energized from the AC power socket from the power line, it is necessary to know the high frequency transfer characteristics with activated AC power line. A simple CDN(Coupling-Decoupling Network) is designed and manufactured for measuring S-parameters of mobile charging circuit with and without AC power line activated. The result shows that the S-parameters of the specific mobile charging circuits are almost the same, independent of AC power line activation. Consequently, the S-parameters without AC line could be used to predict the output response to the EFT/B signals, and it was shown that the proposed methodology predicts the output responses quite accurately, which proves the validness of the methodology presented in this paper.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.8
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• pp.688-693
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• 2013

This paper proposes a new method on attitude control of an underwater robot by using five ABTs (Attitude Ballast Tank). A pipe is connected to the bottom of the ABTs and transfers water by a pump, while another pipe is connected to the top of the ABT to transfer air. The buoyancy center of the underwater robot can be changed by means of the water transfer. This way, the attitude of the underwater robot can be maintained and/or controlled as desired. The changes of the center of gravity and the buoyancy central are estimated by a Lagrangian function which is similar to that for an inverted pendulum. The controller in this paper is designed by modeling of the underwater robot and selecting suitable gains of a PD controller which has fast response characteristics. This paper shows the possibility of the attitude control of an underwater robot by changing the center of gravity and the buoyancy center of the robot. Moreover, experimental results verify that the controller is effective in maintaining Roll/Pitch of the underwater robot with very low power consumption.

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1738-1742
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• 2005

In this study a novel triiodide ion-selective electrode based on a charge transfer complex of iodine and Bis(2-hydroxyacetophenone)butane-2,3-dihydrazone (ICT), as a membrane carrier was prepared. The electrode has a linear dynamic range between 1.0 ${\times}$ $10^{-2}$ and 5.0 ${\times}$ $10^{-7}$ M, with a Nernstian slope of 58. 99 ${\pm}$ 0.3 mV $decade^{-1}$ and detection limit of 3.0 ${\times}$ $10 ^{-7}$ M. The potentiometric response of the proposed sensor is independent of the pH of the solution in the pH range of 3.0-10.0. The electrode possesses the advantages of short conditioning time, fast response time, and especially, very good selectivity over a large number of common organic and inorganic anions. The electrode can be used for at least 6 months without any considerable divergences in the potentials. It was used as an indicator electrode in potentiometric titration of triiodide ion with thiosulfate.

• Carbon letters
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• v.26
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• pp.88-94
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• 2018

This manuscript explains the effective determination of urea by redox cyclic voltammetric analysis, for which a modified polypyrrole-graphene oxide (PPY-GO, GO 20% w/w of PPY) nanocomposite electrode was developed. Cyclic voltammetry measurements revealed an effective electron transfer in 0.1 M KOH electrolytic solution in the potential window range of 0 to 0.6 V. This PPY-GO modified electrode exhibited a moderate electrocatalytic effect towards urea oxidation, thereby allowing its determination in an electrolytic solution. The linear dependence of the current vs. urea concentration was reached using square-wave voltammetry in the concentration range of urea between 0.5 to $3.0{\mu}M$ with a relatively low limit of detection of $0.27{\mu}M$. The scanning electron microscopy was used to characterize the morphologies and properties of the nanocomposite layer, along with Fourier transform infrared spectroscopy. The results indicated that the nanocomposite film modified electrode exhibited a synergistic effect, including high conductivity, a fast electron-transfer rate, and an inherent catalytic ability.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1945-1950
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• 2011

The pyridinolysis of methyl phenyl phosphinic chloride is investigated kinetically in acetonitrile at -20.0 $^{\circ}C$. The Hammett and Br${\o}$nsted plots for substituent X variations in the nucleophiles are biphasic concave downwards with a break point at X = H, and unusual positive ${\rho}_X$ (= 2.94) and negative ${\beta}_X$ (= -0.48) values are obtained for the strongly basic nucleophiles. A stepwise mechanism with a rate-limiting step change from bond breaking for the weakly basic pyridines to bond formation for the strongly basic pyridines is proposed on the basis of biphasic concave downward Hammett and Br${\o}$nsted plots. Unusual positive ${\rho}_X$ and negative ${\beta}_X$ values are rationalized by the isokinetic relationship. The pyridinolyses and anilinolyses of four $R_1R_2$P(=O)Cl-type substrates, dimethyl, diethyl, methyl phenyl, and diphenyl phosphinic chlorides in acetonitrile are compared to obtain systematic information on phosphoryl transfer reaction mechanism. The combination of the two ligands, Me and Ph, shows unexpected kinetic results for both the anilinolysis and pyridinolysis: greatest magnitude of $k_H/k_D$ (= 2.10) involving deuterated anilines $[XC_6H_4NH_2(D_2)]$ for the anilinolysis, and exceptionally fast rate and biphasic concave downward free energy correlation for the pyridinolysis.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.12
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• pp.978-982
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• 2010

For mass information transfer, the optical communication using optic fiber has been widely used. Especially, in the field of medical image, the large data is digitalized based on the standard image and it is used for telemedicine with this method. Therefore, to transfer the large amount of data fast and effectively POF (Plastic Optical Fiber) can be used and the development of optic connector for connection between POFs is very important. In this study, for stable optical coupling of POF optic fiber Ferrule and Sleeve were designed and produced by considering the bond stability and the insertion loss according to the physical contact and roughness profile was evaluated. As a result of examining the insertion loss by physical contact method of two optic fibers, it showed the loss was about 1.895dB. According to the results from studying the condition of grinding section for POF mass production, the mass production condition was established as POF profile roughness of 6nm and the loss of 0.2dB or lower by controlling the film size and time step by step.

• The KIPS Transactions:PartA
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• v.15A no.5
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• pp.287-294
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• 2008

A tag collision arbitration algorithm for RFID passive tags is one of the important issues for fast tag identification, since reader and tag have a shared wireless channel in RFID system. This paper suggests Hyper-Hybrid Query Tree algorithm to prevent the tag-collisions. The suggested algorithms determine the specified point in time for tag to transfer ID to reader by using value 1 of the upper 3 bit based on Query Tree. Also, because the transferred upper 3 bits of tag is different depending on the time of transfer, it is possible to predict in the suggested Algorithm. In the performance evaluation through simulation, it shows the suggested algorithm has higher performance in the number of queries compared to other Tree-based protocols.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1377-1399
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• 2020

In search and rescue mission, micro aerial vehicles (MAVs) are typically used to capture image and video from an aerial perspective and transfer the data to the ground station. Because of the power limitation, a cluster of MAVs are required for a large search area, hence an ad-hoc wireless network must be maintained to transfer data more conveniently and fast. However, the unstable link and the intermittent connectivity between the MAVs caused by MAVs' movement may challenge the packet forwarding. This paper proposes a delay tolerant packet forwarding algorithm based on location estimation for MAV networks, called DTN_est algorithm. In the algorithm, ferrying MAVs are used to transmit data between MAVs and the ground station, and the locations of both searching MAVs and ferrying MAVs are estimated to compute the distances between the MAVs and destination. The MAV that is closest to the destination is selected greedy to forward packet. If a MAV cannot find the next hop MAV using the greedy strategy, the packets will be stored and re-forwarded once again in the next time slot. The experiment results show that the proposed DTN_est algorithm outperforms the typical DTN_geo algorithm in terms of packet delivery ratio and average routing hops.

• Journal of Mechanical Science and Technology
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• v.19 no.10
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• pp.1957-1963
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• 2005

In this study, external condensation heat transfer coefficients (HTCs) of six flammable refrigerants of propylene (RI270), propane (R290), isobutane (R600a), butane (R600), dimethylether (RE170), and HFC32 were measured at the vapor temperature of $39^{\circ}C$ on a 1023 fpm low fin and Turbo-C tubes. All data were taken under the heat flux of $32\~116\;and\;42\~142kW/m^2$ for the low fin and Turbo-C tubes respectively. Flammable refrigerants' data obtained on enhanced tubes showed a typical trend that external condensation HTCs decrease with increasing wall subcooling. HFC32 and DME showed up to $30\%$ higher HTCs than those of HCFC22 due to their excellent thermophysical properties. Propylene, propane, isobutane, and butane showed similar or lower HTCs than those of HCFC22. Beatty and Katz' correlation predicted the HTCs of the flammable refrigerants obtained on a low fin tube within a mean deviation of $7.3\%$. Turbo-C tube showed the best performance due to its 3 dimensional surface geometry for fast removal of condensate.

• Journal of the Korean Wood Science and Technology
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• v.38 no.1
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• pp.43-48
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• 2010

This study was aimed at offering basic data to develop a new use of sawdust and rice husk. The results of this study were as follows: In surface temperature of ceramics by resin impregnation rate, the velocity was great in the early time of heat transfer because the temperature precipitously increased to 10 minutes elapsed. Also, the surface temperature of ceramics manufactured in resin impregnation rate of 60~70% indicated the highest. Heat transfer was fast in terms of the changes in surface temperature of ceramics according to the carbonization temperature, as because the density of ceramics made on condition of the carbonization temperature of $1000^{\circ}C$and $1200^{\circ}C$ was high. Moreover, ceramics maintained heat for a long time because the descent velocity of surface temperature of ceramics was slower than that of heater.