• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.156-158
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• 2018

The inconsistencies between paralleled battery cells are becoming more considerable issue in high capacity battery applications like electric vehicles. Due to differences in state-of-charge (SOC) and internal resistance within individual cells in parallel, charging or discharging current is not appropriately balanced to each cell in terms of SOC, which may shorten the lifetime or sometimes cause safety issues. In this paper, an intelligent cell-balancing algorithm is proposed to overcome the inconsistency issue especially for paralleled battery cells. In this scheme, SOC information collected in the sub-BMS module is sent to the main-BMS module, where the number of parallel cells to be connected to DC bus is continuously updated based on the suggested SOC comparison rule. To verify the method, operation of the algorithm on 4 paralleled battery cells are simulated on Matlab/Simulink. The simulation result shows that the SOCs of paralleled cells are evenly redistributed. It is expected that the proposed algorithm provides high reliable and prolong the life cycle and working capacity of the battery pack.

• 대한지역사회영양학회지
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• 제10권3호
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• pp.303-310
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• 2005

The purpose of this study was to compare the nutrient intake and foodservice satisfaction of homebound elderly had lunch at the local community centers by the difference of meal service charge. Two local community center with cons-regate meal service program located in Daegu and Gyongsan were selected; one with free of meal service charge (F), and the other with 500-1,000 won for meal service charge (K), According to the dietary assessment, energy and nutrient intakes of the 156 elderly subjects were as a whole under the Korean Recommended Dietary Allowance (RDA). Elderly or F service conte. showed higher $\%$ RDA for the selected nutrients and MAR (mean adequacy ratio) than those of K service center (p<0.001). Participants were satisfied with most of the congregation meal service from community conte. with different reasons such as 'tasty (K service center)' and 'free of charge (F service center)'. In conclusion, elderly had the lunch at the community center with free of meal service charge was poor nutrition status and lower socioeconomic level than the other type of community center in this area. Therefore, healthy menu for elderly should be developed and managed by professional dietitian, as well as its impact on health status of this group, and congregate meal service system might be extended to the homebound elderly of whole community with free of charge.

• 대한전자공학회논문지SD
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• 제46권12호
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• pp.80-86
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• 2009

전하펌프의 성능은 공급전압에 의해 크게 영향을 받는다. 본 논문에서는 표준 twin-well CMOS 로직 공정으로 제작 가능하며, 낮은 공급전압에서도 높은 효율을 갖는 새로운 전하펌프 회로를 제안하고 검증하였다. 제안한 전하펌프는 이중의 전하 전달 경로와 간단한 2-phase 클락을 사용한다. 한 주기의 펌핑 사이클 동안 각 펌핑 단에서 입력전압을 2배로 승압하며, 상보적으로 연결된 PMOS 트랜지스터를 전달 스위치로 사용하여 트랜지스터의 문턱전압에 의한 전압강하 없이 승압된 전압을 다음 승압 단으로 전달한다. 시뮬레이션과 측정을 통해 제안한 전하펌프를 검증하였으며, 동일한 공정조건에서 제작 가능한 기존 전하펌프들 보다 높은 출력전압과 큰 전류 구동능력 그리고 더 높은 전력효율을 가진다는 것을 확인하였다.

• 한국분무공학회지
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• 제14권4호
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• pp.171-177
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• 2009

This study proposes a new stratified charge system for low emission and ultra lean burn. In order to examine combustion characteristics of the new system, sparkplug with a hole at positive pole and a common CNG injector for injecting fuel were used in this study as injector-type spark plug. The new stratified charge system injects fuel of extremely small quantities and ignites mixture around sparkplug gap. Also, the system was fitted in a visualized constant volume chamber. Then, for analysis of the combustion characteristics, we examined combustion pressure, lean inflammable limit, and visualized combustion flame according to equivalence ratio by comparison with homogeneous charge (HC) method and the new stratified charge (SC) method. As results of this study, in the case of using this system, the propagation speed of initial flame was increased and total combustion period was reduced in the ultra lean burn in the same equivalence ratio. These phenomena occurred clearly under the conditions of lean equivalence ratio. Furthermore, the lean inflammable limit of mixture was extended by using the injector-type spark plug.

• 한국정보통신학회논문지
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• 제21권5호
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• pp.885-892
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• 2017

본 논문에서는 기존 전원차단회로의 공급전원 차단 복귀 시간 지연 문제를 해결하기 위하여 고속 방전 충전 스위칭 기능을 갖는 새로운 전원차단회로를 제안하였다. 제안된 전원차단회로는 공급전원 고속 차단 후 복귀(충전) 속도를 증가시키도록 설계함으로써 전자시스템의 방사선 노출 시간과 펄스 방사선이 지나간 후 정상동작하기 위한 시간을 줄였다. 하드웨어를 구현하기 전 방전 충전 시간의 시뮬레이션은 Cadence 사의 pspice tool을 이용하여 진행하였으며 소자레벨에서 DUT(Device Under Test) 보드를 제작하였다. 전원차단회로의 비교 측정은 24V용 인공위성 전자소자를 대상으로 수행되었다. 그 결과, 제안된 회로는 기존 회로에 비하여 방전속도 96.8%, 복귀속도 27.3% 향상으로 고속 기능이 구현됨을 확인하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.99-99
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• 2013

In this talk, I will present two research works in progress, which are: i) mapping of piezoelectric polarization and associated charge density distribution in the heteroepitaxial InGaN/GaN multi-quantum well (MQW) structure of a light emitting diode (LED) by using inline electron holography and ii) in-situ observation of the polarization switching process of an ferroelectric Pb(Zr1-x,Tix)O3 (PZT) thin film capacitor under an applied electric field in transmission electron microscope (TEM). In the first part, I will show that strain as well as total charge density distributions can be mapped quantitatively across all the functional layers constituting a LED, including n-type GaN, InGaN/GaN MQWs, and p-type GaN with sub-nm spatial resolution (~0.8 nm) by using inline electron holography. The experimentally obtained strain maps were verified by comparison with finite element method simulations and confirmed that not only InGaN QWs (2.5 nm in thickness) but also GaN QBs (10 nm in thickness) in the MQW structure are strained complementary to accommodate the lattice misfit strain. Because of this complementary strain of GaN QBs, the strain gradient and also (piezoelectric) polarization gradient across the MQW changes more steeply than expected, resulting in more polarization charge density at the MQW interfaces than the typically expected value from the spontaneous polarization mismatch alone. By quantitative and comparative analysis of the total charge density map with the polarization charge map, we can clarify what extent of the polarization charges are compensated by the electrons supplied from the n-doped GaN QBs. Comparison with the simulated energy band diagrams with various screening parameters show that only 60% of the net polarization charges are compensated by the electrons from the GaN QBs, which results in the internal field of ~2.0 MV cm-1 across each pair of GaN/InGaN of the MQW structure. In the second part of my talk, I will present in-situ observations of the polarization switching process of a planar Ni/PZT/SrRuO3 capacitor using TEM. We observed the preferential, but asymmetric, nucleation and forward growth of switched c-domains at the PZT/electrode interfaces arising from the built-in electric field beneath each interface. The subsequent sideways growth was inhibited by the depolarization field due to the imperfect charge compensation at the counter electrode and preexisting a-domain walls, leading to asymmetric switching. It was found that the preexisting a-domains split into fine a- and c-domains constituting a $90^{\circ}$ stripe domain pattern during the $180^{\circ}$ polarization switching process, revealing that these domains also actively participated in the out-of-plane polarization switching. The real-time observations uncovered the origin of the switching asymmetry and further clarified the importance of charged domain walls and the interfaces with electrodes in the ferroelectric switching processes.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권2호
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• pp.286-291
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• 2015

For highly scalable NAND flash memory applications, a compact ($4F^2/cell$) nonvolatile memory architecture is proposed and investigated via three-dimensional device simulations. The back-channel program/erase is conducted independently from the front-channel read operation as information is stored in the form of charge at the backside of the channel, and hence, read disturbance is avoided. The memory cell structure is essentially equivalent to that of the fully-depleted transistor, which allows a high cell read current and a steep subthreshold slope, to enable lower voltage operation in comparison with conventional NAND flash devices. To minimize memory cell disturbance during programming, a charge depletion method using appropriate biasing of a buried back-gate line that runs parallel to the bit line is introduced. This design is a new candidate for scaling NAND flash memory to sub-20 nm lateral dimensions.

• Journal of Magnetics
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• 제10권4호
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• pp.149-151
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• 2005

The electric properties of a single crystal bismuth telluride doped with a small concentration of Erbium, $Bi_{z-x}Er_xTe_3$ with x = 0.002, are investigated as a function of temperature. The resistivity was obtained by using the van der Pauw method. The measured electrical resistivity is 78 ${\mu}{\Omega}cm$ at 4.2 K. The charge density of $Bi_{z-x}Er_xTe_3$ is found to be $2{\times}10^{19}/cm^3$ at 4.2 K. It turns out that $Bi_{z-x}Er_xTe_3$ is a p-type semiconductor. It is discussed that the high mobility and less density support that $Bi_{z-x}Er_xTe_3$ is a potential sensor with high energy resolution. Comparison with an established material (i.e. Au:Er alloy) is also discussed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.997-998
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• 2007

This paper deals with analytical solution concerning the image method using the magnetic charge instead of 3D FEA(finite element analysis) in the slotless single air-gap motor. The theory of analytical method and the design procedures are introduced. The reliability and validity of proposed analytical solution are verified through the comparison with the results of commercial 3D FE software. In addition, calculation time between proposed analytical solution and 3D FEA is compared. Finally, characteristics, such as Back-EMF and phase resistance, between calculated and experimental results are compared. From the verification with 3D FEA and experimental results, it is proved that presented analytical method provided very effective and precise results.

• Transactions on Electrical and Electronic Materials
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• 제17권4호
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• pp.212-216
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• 2016

A reflective electronic display that uses negatively and positively charged particles has excellent bistability, a welldefined threshold voltage, and an extremely fast response time in comparison with other reflective displays. This type of display shows images through the movement of charged particles whose motion depends on the value of q/m (charge per mass for a particle). However, the ratio q/m can easily be changed by the forces acting on the charged particles in a cell of the panel and by friction that occurs after mixing oppositely charged particles and in the particle-insertion process. In this study, we propose a method to determine the appropriate range of q/m by using the reflectivity and response time of charged particles to modify q/m. In this manner, the electrical and optical properties of reflective displays are improved.