• Journal of the Korean Ceramic Society
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• v.20 no.4
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• pp.315-323
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• 1983

Effect of NiO and $MnO_2$ addtivies on the dielectric piezoelectrics and polarization-reversal properties of $(Pb_{0.936} La_{0.064})$$(Zr_{0.60}Ti_{0.40})O_3$ ceramics have been investigated. The specimens were prepared by the mixed oxide techni-que and atmosphere sintering method. The room temperature X-ray diffraction studies show that perfect perovskite solution with tetragonal structure was obtained from PLZT and its additives. The dielectric constant and dissipation factor decreased with the addition of both NiO and $MnO_2$ The Curie of Curie temperature was not observed but they displayed broadened maxima. The planar coupling factor was improved by addition of NiO and also increased with increasing sintering time carried out at 105$0^{\circ}C$ Addition of $MnO_2$ yielded a markedly high mechanical quality factor. The space-charge field decreased with the addition of NiO but increased with the addition of $MnO_2$ The planar coupling factor and space-charge field showed same dependence on the additivies. The tetragonality Curie temperature and planar coupling factor of $(Pb_{0.936} La_{0.064})$$(Zr_{0.60}Ti_{0.40})O_3$ were higher than those of $(Pb_{0.936} La_{0.064})$$(Zr_{0.568}NU_{0.032}Ti_{0.40})_{0.984}O_3$ but the grain size lattic parameter dielectric constant dissipation factor mechanical quality factor and space-charge field of the former were lower than those of the latter.

• The Journal of the Acoustical Society of Korea
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• v.41 no.6
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• pp.610-620
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• 2022

An acoustic vector sensor can simultaneously receive vector quantities, such as particle velocity and acceleration, as well as acoustic pressure at one location, and thus it can be used as a single input multiple output receiver in underwater acoustic communication systems. On the other hand, vector signals received by a single vector sensor have different channel characteristics due to the azimuth angle between the source and receiver and the difference in propagation angle of multipath in each component, producing different communication performances. In this paper, we propose a channel parameter-based weighting method to improve the performance of an acoustic communication system using a single vector sensor. To verify the proposed method, we used communication data collected from the experiment conducted during the KOREX-17 (Korea Reverberation Experiment). For communication demodulation, block-based time reversal technique which is robust against time-varying channels were utilized. Finally, the communication results showed that the effectiveness of the channel parameter-based weighting method for the underwater communication system using a single vector sensor was verified.

• Korean Institute of Interior Design Journal
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• v.27 no.1
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• pp.29-38
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• 2018

This research is to analyze the change of pupil size in gender through the eye-tracking experiment in large complex cultural space. It is meaningful that figured out the common characteristics and differences from gender observation characteristics. Through this research, the analyzed results of the observation time measurement that appeared from the fixation and saccades pupil indicator able to define as follows. Firstly, it was suggested that there were differences between each gender and participants through extract pupil size that can be the standard examples for the case from male and female and the process of extracting the relative pupil size change on the hourly range. From the specific time range, it was possible to indicate bending characteristics and reversal phenomena of Fixation and Saccades. Second, the result was found equally from both male and female group that the rapid increment of pupil size at initial time range immediately after the eye-tracking experiment has been initiated. This can be considered to actively accepting the stress given by the subject through the extended pupil after 10 seconds that compare to indicated very low pupil size between 0 to 10 seconds after starting the experiment. Third, meanwhile 0 to 10 seconds after initial observation are the time of sudden change in the pupil size, therefore these time range data cannot be regarded as observed in the appropriate condition. Thus, it able to define the highest times of emotional processing for male as 10 to 80 seconds, and for female as 10 to 70 seconds. There was no definition of the time range data for observation experiment from previous research, this data can be considered to stable time to observation through the pupil extension. Therefore, it is possible to set suitable time of observation experiment to be around 70 to 80 seconds exclude initial experiment time.

• The Journal of the Acoustical Society of Korea
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• v.36 no.6
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• pp.378-386
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• 2017

Accurate distance measurement between maneuver target in underwater and measuring devices is required to perform quantitative test evaluation in marine weapons system R&D process. In general, the target distance is measured using a one-way ToA (Time of Arrival) method that calculates the time difference between transmitted and received signals from the two accurately synchronized devices. However, the distance estimation performance is degraded because of the multi-path environments. In this paper, the time-variant transfer function of complex underwater environment is estimated from each received data frame using RBD (Ray-based Blind Deconvolution), and the estimated time-variant transfer function is then used to get rid of the effect about complex underwater environment and to recover the data signal using PTRM (Passive Time Reversal Mirror). The result from the simulation and experimental data show that the suggested method improve the distance estimation performance when comparing with the conventional ToA method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.5
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• pp.243-247
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• 2009

For obtaining high speed data rate, underwater acoustic communication has several problems by the different environmental problem compared to wireless communication. To overcome this problem, the research is going steadily. In this paper, the property of underwater acoustic channel is considered, and the explanation of recently various method of transmitting and receiving and the domestic and foreign trend of underwater acoustic communication are taken into account.

• Biomolecules & Therapeutics
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• v.18 no.4
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• pp.375-385
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• 2010

Conventional cancer chemotherapy is seriously limited by tumor cells exhibiting multidrug resistance (MDR), which is caused by changes in the levels or activity of membrane transporters that mediate energy-dependent drug efflux and of proteins that affect drug metabolism and/or drug action. Cancer scientists and oncologists have worked together for some time to understand anticancer drug resistance and develop pharmacological strategies to overcome such resistance. Much focus has been on the reversal of the MDR phenotype by inhibition of ATP-binding cassette (ABC) drug transporters. ABC transporters are a family of transporter proteins that mediate drug resistance and low drug bioavailability by pumping various drugs out of cells at the expense of ATP hydrolysis. Many inhibitors of MDR transporters have been identified, and though some are currently undergoing clinical trials, none are in clinical use. Herein, we briefly review the status of MDR in human cancer, explore the pathways of MDR in chemotherapy, and outline recent advances in the design and development of MDR modulators.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.332-336
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• 2007

Temperature is an essential process variable in nanoimprint lithography(NIL) where the temperature varies between room temperature and above the glass transition temperature. To simulate NIL process, we employ both the Nose-Poincare method for temperature controlled molecular dynamics(MD) and force field for polymer material i.e. polymethyl methacrylate(PMMA), which is most widely selected as NIL resist. Nose-Poincare method, which convinces the conservation of Hamiltonian structure and time-reversal symmetry, overcomes the drawbacks inherent in the conventional methods such as Nose thermostat and Nose-Hoover thermostat. Thus, this method exhibits enhanced numerical stability even when the temperature fluctuation is large. To describe PMMA, we adopt the force field which account for bond stretch, bending, torsion, inversion, partial charge, and van der Waals energy.

• Journal of Magnetics
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• v.5 no.2
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• pp.35-39
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• 2000

The correlation between the activation volumes of wall-motion and nucleation processes in Co/Pd multilayers has been investigated. Each activation volume was estimated from the field dependence of the wall-motion speed and the nucleation rate, respectively, based on time-resolved domain patterns grabbed by a MOKE microscope system. Both the activation volumes are changed in the same manner around $0.2\sim1.1\times10^{-17}cm^3$ with changes in the multilayered structure. Interestingly, the correlation between the activation volumes is sensitive to the multilayered structure; the wall-motion activation volume is smaller than the nucleation activation volume for a sample having a smaller number of repeats and a thinner Co-layer thickness, and vice versa. The correlation is closely related with the contrasting reversal modes; the process having the smaller activation volume dominates.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.8
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• pp.3577-3581
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• 2012

Small cell lung cancer (SCLC) is characterized by a short cell doubling time, rapid progression and early occurrence of blood-borne and lymph metastasis. The malignancy is the highest of all lung cancer types. Although SCLC has a relatively good initial response to chemotherapy as well as radiotherapy, relapse or disease progression may occur quickly after the initial treatment. Drug resistance, especially multi-drug resistance, is the most important cause of failure of SCLC chemotherapy. This article provides a brief update of research on mechanisms of drug resistance in SCLC and reversal strategies.

• Journal of the Korean Wood Science and Technology
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• v.27 no.4
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• pp.51-56
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• 1999

Finite element method was utilized to analyze crack tip stress and displacement field under drying stress case as stepwise loading. Opening mode of single-edge-notched model was employed and analyzed by linear elastic fracture mechanics of plane stress case. The drying stresses were applied as stepwise loads at the boundary elements of the model with 10 steps of time serial. The stress intensity factor($K_I$) for opening mode reached to its maximum just prior to the stress reversal. The $K_I$ from the displacement fields revealed 1.7 times higher than those from stress fields. By comparing the two sets of $K_I$ from displacement and stress fields, single parameter $K_I$ showed its validity to characterize displacement fields around the crack tip front while stress field could not be characterized due to large variations between two sets of data.