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Jungdae Kim,Jinseong Kim,Taimin Noh,Jeongwook Kim,이희수 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.4
The effect of thulium oxide (Tm2O3) doping on the electrical properties of barium titanate (BaTiO3) ceramics was investigated in terms of the crystallinity and core-shell structure. The electrical properties of the Tm2O3 doped BaTiO3 were evaluated by measurements of the dielectric constant and temperature coefficient of capacitance (TCC) in addition to insulation resistance (IR). The dielectric constant and the IR of an undoped dielectric specimen were about 30% and 20%, respectively, lower than the values of a 1 mol% Tm2O3 doped specimen which met the reliability test condition in the range from -55 to 125 oC. The addition of Tm2O3 in BaTiO3 contributed to the enhanced electrical properties; however, an excessive addition had bad effects on the characteristics of BaTiO3 due to the formation of a second phase and the expansion of the shell region. This could be explained by the fact that the improved dielectric properties and IR according to the appropriate doping of Tm2O3, were revealed by an increase of the crystallinity and the reinforcement of the core-shell structure in BaTiO3.
Moment of the ratio and approximate MLEs of parameters in a bivariate Pareto distribution
Kim, Jungdae The Korean Data and Information Science Society 2012 한국데이터정보과학회지 Vol.23 No.6
We shall derive the moment of the ratio Y/(X + Y) and the reliability P(X < Y ), and then observe the skewness of the ratio in a bivariate Pareto density function of (X, Y). And we shall consider an approximate MLE of parameters in the bivariate Pareto density function.
Kim, Jungdae,Nam, Hyoungdo,Qin, Shengyong,Kim, Sang-ui,Schroeder, Allan,Eom, Daejin,Shih, Chih-Kang American Institute of Physics 2015 Review of scientific instruments Vol.86 No.9
<P>We report on the design of a compact low temperature scanning tunneling microscope (STM) having in-situ sample preparation capability. The in-situ sample preparation chamber was designed to be compact allowing quick transfer of samples to the STM stage, which is ideal for preparing temperature sensitive samples such as ultra-thin metal films on semiconductor substrates. Conventional spring suspensions on the STM head often cause mechanical issues. To address this problem, we developed a simple vibration damper consisting of welded metal bellows and rubber pads. In addition, we developed a novel technique to ensure an ultra-high-vacuum (UHV) seal between the copper and stainless steel, which provides excellent reliability for cryostats operating in UHV. The performance of the STM was tested from 2 K to 77 K by using epitaxial thin Pb films on Si. Very high mechanical stability was achieved with clear atomic resolution even when using cryostats operating at 77 K. At 2 K, a clean superconducting gap was observed, and the spectrum was easily fit using the BCS density of states with negligible broadening.</P>
Fabrication of ZnCoO nanowires and characterization of their magnetic properties
Kim, Bum-Su,Lee, Seunghun,Kim, Won-Kyung,Park, Ji-Hun,Cho, Yong Chan,Kim, Jungdae,Cho, Chae Ryong,Jeong, Se-Young Springer 2014 NANOSCALE RESEARCH LETTERS Vol.9 No.1
<P>Hydrogen-treated ZnCoO shows magnetic behavior, which is related to the formation of Co-H-Co complexes. However, it is not well known how the complexes are connected to each other and with what directional behavior they are ordered. In this point of view, ZnCoO nanowire is an ideal system for the study of the magnetic anisotropy. ZnCoO nanowire was fabricated by trioctylamine solution method under different ambient gases. We found that the oxidation of trioctylamine plays an essential role on the synthesis of high-quality ZnCoO nanowires. The hydrogen injection to ZnCoO nanowires induced ferromagnetism with larger magnetization than ZnCoO powders, while becoming paramagnetic after vacuum heat treatment. Strong ferromagnetism of nanowires can be explained by the percolation of Co-H-Co complexes along the <I>c</I>-axis.</P>
Influence of quantum well states on the formation of Au–Pb alloy in ultra-thin Pb films
Kim, Jungdae,Qin, Shengyong,Zhang, Yi,Zhu, Wenguang,Shih, Chih-Kang Elsevier 2015 Surface science Vol.632 No.-
<P><B>Abstract</B></P> <P>The thickness dependence of Au–Pb alloy formation on Pb quantum films is studied via <I>in-situ</I> low-temperature scanning tunneling microscopy/spectroscopy (STM/S). 2D islands with moiré pattern are observed on top of Pb films when sub-monolayer Au is deposited onto Pb films at a substrate temperature of 90K. After annealing at up to 250K, various types of 2D islands, including Au–Pb alloys, are formed and show very different electronic structures. A detailed STS study suggests that the formation of these islands is directly related to the quantum well states (QWS) of Pb films, indicating quantum size effects (QSE) on the formation of Au–Pb alloys.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The thickness dependence of Au-Pb alloy formation on Pb quantum films is observed via <I>in-situ</I> STM/S. </LI> <LI> DFT shows Au can get into either subsurface interstitial sites or surface-layer substitutional sites of Pb(111) surface. </LI> <LI> 2D islands with moiré pattern are observed on Pb films when sub-monolayer Au is deposited onto Pb films at 90K. </LI> <LI> 2D islands with moiré pattern are transformed into various types of Au-Pb alloys after annealing at up to 250K. </LI> <LI> A STS study suggests that the formation of these Au-Pb alloys is directly related to the quantum well states of Pb films. </LI> </UL> </P>
Kim, Jungdae,Kim, Yong-ung,Lee, Young Joo,Kobayashi, Masaki,Tsutsumi, Yuji,Kondo, Ryuichiro,Lee, Seung Ki,Soh, Kwang-Sup The Pharmaceutical Society of Japan 2007 Journal of Health Science Vol.53 No.4
<P>We analyzed the change in the intensities of spontaneous ultraweak photon emission during the growth of the cell population of HeLa cell line using a cell culture system. Comparisons of the temporal change of intensities of spontaneous ultraweak photon emission with that of the growth curve showed that the intensity followed almost the same course with the change rate kinetics of cell population. The analysis of cell viability during the growth of the cell population indicated that there is a close relationship between the intensities of photon emission and proliferative rate of viable cells. The flow-cytometric analysis indicated that the intensities of the photon emission are related primarily to the 2n diploid cell equivalent populations. We suggest that the spontaneous ultraweak photon emission is mainly involved in the changes of the ploidy number during the proliferative process of the cancer cell line. The therapeutic effects of acupuncture may be explained scientifically by the spontaneous ultraweak photon emissions from the cells during the changes of its ploidy number in the anatomical structure of acupuncture meridians.</P>
A Design of Economic CUSUM Control Chart Incorporating Quality Loss Function
Jungdae Kim 한국산업경영시스템학회 2018 한국산업경영시스템학회지 Vol.41 No.4
Quality requirements of manufactured products or parts are given in the form of specification limits on the quality characteristics of individual units. If a product is to meet the customer’s fitness for use criteria, it should be produced by a process which is stable or repeatable. In other words, it must be capable of operating with little variability around the target value or nominal value of the product’s quality characteristic. In order to maintain and improve product quality, we need to apply statistical process control techniques such as histogram, check sheet, Pareto chart, cause and effect diagram, or control charts. Among those techniques, the most important one is control charting. The cumulative sum (CUSUM) control charts have been used in statistical process control (SPC) in industries for monitoring process shifts and supporting online measurement. The objective of this research is to apply Taguchi's quality loss function concept to cost based CUSUM control chart design. In this study, a modified quality loss function was developed to reflect quality loss situation where general quadratic loss curve is not appropriate. This research also provided a methodology for the design of CUSUM charts using Taguchi quality loss function concept based on the minimum cost per hour criterion. The new model differs from previous models in that the model assumes that quality loss is incurred even in the incontrol period. This model was compared with other cost based CUSUM models by Wu and Goel, According to numerical sensitivity analysis, the proposed model results in longer average run length in in-control period compared to the other two models.
Kim, Jungdae,Lim, Jaekwan,Kim, Hongbae,Ahn, Saeyoung,Sim, Sung-Bo,Soh, Kwang-Sup Taylor Francis 2006 Electromagnetic biology and medicine Vol.25 No.2
<P>A scanning system for the detection of spontaneous ultraweak photon emission from nude mice with transplanted tumors is presented. A photomultiplier tube (PMT) with an effective area of 15 mm diameter was used for measuring photon emission in a wavelength range from 300 to 650 nm. Tumors were induced in nude mice by transplantation of an ovarian cancer cell line into the back of mice. The PMT was moved for scanning over the whole body of a mouse placed in a dark box. The profiles of the intensities of photon emissions from the tumor mice are presented and compared with those obtained from the control mice.</P>