Continuous Control of Charge Transport in Bi‐Deficient BiFeO₃ Films Through Local Ferroelectric Switching

Kim, Tae Heon,Jeon, Byung Chul,Min, Taeyoon,Yang, Sang Mo,Lee, Daesu,Kim, Yong Su,Baek, Seung‐,Hyub,Saenrang, Wittawat,Eom, Chang‐,Beom,Song, Tae Kwon,Yoon, Jong‐,Gul,Noh, Tae Won WILEY‐VCH Verlag 2012 Advanced Functional Materials Vol.22 No.23

<P><B>Abstract</B></P><P>It is demonstrated that electric transport in Bi‐deficient Bi<SUB>1‐<I>δ</I></SUB>FeO<SUB>3</SUB> ferroelectric thin films, which act as a p‐type semiconductor, can be continuously and reversibly controlled by manipulating ferroelectric domains. Ferroelectric domain configuration is modified by applying a weak voltage stress to Pt/Bi<SUB>1‐<I>δ</I></SUB>FeO<SUB>3</SUB>/SrRuO<SUB>3</SUB> thin‐film capacitors. This results in diode behavior in macroscopic charge‐transport properties as well as shrinkage of polarization‐voltage hysteresis loops. The forward current density depends on the voltage stress time controlling the domain configuration in the Bi<SUB>1‐<I>δ</I></SUB>FeO<SUB>3</SUB> film. Piezoresponse force microscopy shows that the density of head‐to‐head/tail‐to‐tail unpenetrating local domains created by the voltage stress is directly related to the continuous modification of the charge transport and the diode effect. The control of charge transport is discussed in conjunction with polarization‐dependent interfacial barriers and charge trapping at the non‐neutral domain walls of unpenetrating tail‐to‐tail domains. Because domain walls in Bi<SUB>1‐<I>δ</I></SUB>FeO<SUB>3</SUB> act as local conducting paths for charge transport, the domain‐wall‐mediated charge transport can be extended to ferroelectric resistive nonvolatile memories and nanochannel field‐effect transistors with high performances conceptually.</P>

Origin of Proteinuria as Observed from Qualitative and Quantitative Analysis of Serum and Urinary Proteins

Takahashi, Shori Korean Society of Pediatric Nephrology 2015 Childhood kidney diseases Vol.19 No.2

It is well known that proteins present in the primary urine are reabsorbed in the renal proximal tubules, and that this reabsorption is mediated via the megalin-cubilin complex and the neonatal $Fc{\gamma}$ receptor. However, the reabsorption is also thought to be influenced by an electrostatic interaction between protein molecules and the microvilli of the renal proximal tubules. By analyzing the charge diversity of urinary IgG, we showed that this reabsorption process occurs in a cationic charge-preferential manner. The charge-selective molecular sieving function of the glomerular capillary walls has long been a target of research since Brenner et al. demonstrated the existence of this function by a differential clearance study by using the anionic dextran sulfate polymer. However, conclusive evidence was not obtained when the study was performed using differential clearance of serum proteins. We noted that immunoglobulin (Ig) A and IgG have similar molecular sizes but distinct molecular isoelectric points. Therefore, we studied the differential clearance of these serum proteins (clearance IgA/clearance IgG) in podocyte diseases and glomerulonephritis. In addition, we studied this differential clearance in patients with Dent disease rather than in normal subjects because the glomerular sieving function is considered to be normal in subjects with Dent disease. Our results clearly showed that the charge-selective barrier is operational in Dent disease, impaired in podocyte disease, and lacking in glomerulonephritis.

AC PDP에서 문턱전압 폐곡선을 그리기 위한 소거 전압 및 유휴 시간의 연구

이석기(Seok-Ki Lee),조병권(Byung-Gwon Cho) 한국정보기술학회 2019 한국정보기술학회논문지 Vol.17 No.2

The optimal initial voltage and idle time were investigated to measure the threshold voltage closed curve, which is independent of the state of charge remaining inside the cell on the AC plasma display panel (AC PDP). When voltage is applied to an AC PDP, the wall charge builds up on the electrodes in the inner cell after discharge, which requires appropriate voltage to be designed taking into account the wall charge. Therefore, it is necessary to measure the discharge start voltage along the wall charge state or panel structure stacked inside the cell and a graph showing the difference in potential between the three electrodes in two horizontal and vertical axes is the threshold voltage closed curve. To measure the threshold voltage closed curve, a high voltage should erase the previous wall charge and cause the priming particles remaining inside the cell to disappear by idle time. In this paper, the threshold voltage closed curve was measured with changes in erase voltage and idle time and the optimum conditions were investigated.

Origin of Proteinuria as Observed from Qualitative and Quantitative Analysis of Serum and Urinary Proteins

Shori Takahashi 대한소아신장학회 2015 Childhood kidney diseases Vol.19 No.2

It is well known that proteins present in the primary urine are reabsorbed in the renal proximal tubules, and that this reabsorption is mediated via the megalincubilin complex and the neonatal Fcγ receptor. However, the reabsorption is also thought to be influenced by an electrostatic interaction between protein molecules and the microvilli of the renal proximal tubules. By analyzing the charge diversity of urinary IgG, we showed that this reabsorption process occurs in a cationic charge-preferential manner. The charge‐selective molecular sieving function of the glomerular capillary walls has long been a target of research since Brenner et al. demonstrated the existence of this function by a differential clearance study by using the anionic dextran sulfate polymer. However, conclusive evidence was not obtained when the study was performed using differential clearance of serum proteins. We noted that immunoglobulin (Ig) A and IgG have similar molecular sizes but distinct molecular isoelectric points. Therefore, we studied the differential clearance of these serum proteins (clearance IgA/ clearance IgG) in podocyte diseases and glomerulonephritis. In addition, we studied this differential clearance in patients with Dent disease rather than in normal subjects because the glomerular sieving function is considered to be normal in subjects with Dent disease. Our results clearly showed that the chargeselective barrier is operational in Dent disease, impaired in podocyte disease, and lacking in glomerulonephritis.

Positive Charge-doping on Carbon Nanotube Walls and Anion-directed Tunable Dispersion of the Derivatives

Shin, Ueon-Sang,Knowles, Jonathan C.,Kim, Hae-Won Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.5

An efficient and novel positive charge-doping on the sidewalls of multi-walled carbon nanotubes has been achieved in the presence of tetrahydrofuran as a dopant and Lewis acidic ionic liquids, [bmim]$Sb_nF_{5n+1}$ (n ${\geq}$ 2; bmim = 1-butyl-3-methylimidazolium), as an activator, leaving air-stable derivatives having positively charged sidewalls and the counter anions, [MWCNT$^{y+}$][SbF$_6^-$]$_y$ (MWCNT = multi-walled carbon nanotube). The derivatization took place very fast in one-pot and under mild reaction conditions. The ionic structure enabled a tunable dissolution of the derivatives in various solvents through anion exchange.

Positive Charge-doping on Carbon Nanotube Walls and Anion-directed Tunable Dispersion of the Derivatives

신원상,조나단놀리스,김해원 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.5

An efficient and novel positive charge-doping on the sidewalls of multi-walled carbon nanotubes has been achieved in the presence of tetrahydrofuran as a dopant and Lewis acidic ionic liquids, [bmim]Sb_nF_(5n+1) (n ≥ 2;bmim = 1-butyl-3-methylimidazolium), as an activator, leaving air-stable derivatives having positively charged sidewalls and the counter anions, [MWCNT^(y+)][SbF6_^−]y (MWCNT = multi-walled carbon nanotube). The derivatization took place very fast in one-pot and under mild reaction conditions. The ionic structure enabled a tunable dissolution of the derivatives in various solvents through anion exchange.

바 형태 정전기제거장치의 정전기제거성능 향상을 위한 연구 (2)

이동훈 ( Dong Hoon Lee ),최동수 ( Dong Soo Choi ),김상민 ( Sang Min Kim ),박진철 ( Jin Chul Park ) 한국안전학회(구 한국산업안전학회) 2014 한국안전학회지 Vol.29 No.6

In display such as LCD, LED, and AMOLED or semiconductor related industries are required to have static ionizer in order to produce reliable goods. The most general type of ionization is called, “corona discharge” that has a slight chances to generate unequal and unstable amount of each +/- ion to the target object. Then, the ionization performance will drastically decrease and end up with quality deterioration problem. continually “A study on the improvement of the performance of pulsed AC ion bar(1)”, we have studied consecutive study to improve the current issue via appling “partition wall” at air nozzle surrounding. The results were that the charge decay time and the ion balance was maintained the satisfied range that was within 5 second and ± 50 V for a 180 days period of time. In additions, the contamination status on the electrode surface was investigated for a 180 days. The little particles was deposited on the electrode surface.

Preparation and Characterization of Fe₃O₄/MWNTs Composites

박수진(Park, Soo-Jin),김영하(Kim, Young-Ha) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06

In this work, the magnetite (Fe₃O₄)/multi-walled carbon nanotubes (MWNTs) composites for lithium secondary battery were prepared. Nano-Fe₃O₄ was deposited by chemical coprecipitation of Fe^{2+} and Fe^{3+} in the presence of MWNTs in alkaline solutions. Transmission electron spectroscopy (TEM) and X-ray diffraction (XRD) analyses indicated that nano-Fe₃O₄ particles had a good crystallinity of cubic specimens and many tiny particles attached on the surfaces of the MWNTs. The electrochemical properties of Fe₃O₄/MWNTs composites as anodes in lithium-secondary batteries were evaluated by cyclic voltammetry and galvanostatic charge/discharge techniques. The as-prepared Fe₃O₄/MWNTs composites showed an initial lithium storage capacity of 1120 mAh/g and a reversible capacity of 394 mAh/g after 100 cycles, demonstrating better performance than that of the commercial graphite anode materials.

Optimal Seismic Design of Reinforced Concrete Shear Wall-Frame Structures

Ali Kaveh,Pooya Zakian 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.7

Seismic design of Reinforced Concrete (RC) dual systems is performed as an optimization problem for which the charged system search algorithm is utilized as an optimizer. An efficient structural modeling is also presented for this purpose. Here, first databases are created based on ACI seismic criteria for beams, columns and shear walls. Formulations for optimal seismic design of dual systems (shear wall-frame) are proposed. With some modifications on these formulations, optimal seismic design of RC moment frames can also be performed. This procedure is along with ordinary design constraints and effective seismic design constraints. These constraints consist of beams, columns, shear wall design criteria, and some other seismic provisions. Cost of the structure is considered as the objective function. According to the results of the numerical example, the proposed methodology can be considered as a suitable practical approach for optimal seismic design of reinforced concrete shear wall-frame structures.

플라즈마 디스플레이 패널에서 공통전극에서의 벽전하를 이용한 기입방전특성의 향상

조병권,Cho, Byung-Gwon 대한전자공학회 2013 전자공학회논문지 Vol.49 No.11

플라즈마 디스플레이 패널에서 기입기간 동안 공통전극에서의 벽전하를 이용하여 기입방전특성을 향상시키기 위하여 수정된 구동 파형을 제시한다. 플라즈마 디스플레이의 구동방식에 있어서 초기화 기간 후에 상판의 두 전극에는 음전하가 쌓이게 되고 하판의 기입전극에는 양전하가 쌓이게 된다. 기입기간 중의 기입방전은 주사펄스와 기입펄스가 동시에 인가될 때 발생되는데 주사전극의 음전하와 기입전극의 양전하가 주로 이용된다. 반면에 공통 전극에서는 기입기간 동안 파형인가 없이 전압만 유지하기 때문에 공통전극의 벽전하는 크게 기여하지 않는다. 본 연구에서는 기입기간 중 주사 및 기입 펄스의 인가시각에 맞춰 공통 전극에서도 펄스를 인가하여 기입방전 특성을 조사하였다. 공통 전극에서의 인가전압의 높이와 펄스의 인가시각에 따른 기입 방전특성을 조사하는 실험을 각각 진행하였으며 그 결과 최적의 전압높이와 인가시각 조건하에서 기입방전의 발생시간을 종래보다 약 200 ns 정도 단축시켰다. A modified driving waveform is proposed to improve the address discharge characteristics using wall charge on the common electrodes in plasma display panel. In the driving scheme of plasma display, after a reset period, the negative charge are accumulated on two front electrodes and positive wall charge are accumulated on the address electrode. As the address discharge during an address period is produced when the scan and address pulses are applied at the same time, negative charge on the scan electrodes and positive charge on the address electrodes are mainly used. On the other hand, as the voltage are only maintained without applying the waveform during an address period on the common electrodes, the wall charge is not used on the common electrodes. In this paper, the address discharge characteristics are investigated with changing pulse applying time and applied voltage amplitude on the common electrodes and consequently the producing time of an address discharge are shortened about 200 ns compared with the conventional driving waveform.