• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.33-36
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• 1999

In this paper, $Ba_{0.5}$Sr$_{0.5}$TiO$_3$ thin-films were prepared on Pt/Ti/Si0$_2$/Si substrates by RF magnetron sp-uttering method. We investigated electric and dielectric properties of BST thin-films with various ann-ealing temperature using in-sute RTA. Deposition conditions of BST films were set substrate temperat-ure, 30$0^{\circ}C$ and working gas ratio, Ar:O$_2$=90:10. After BST films deposited, we fabricated a capacitor of MIM structure with Al top electrode for measurement. Post-annealing using RTA performed at 40$0^{\circ}C$, $600^{\circ}C$, 80$0^{\circ}C$ for 60 sec, respectively. Also we exacted crystallization and composition of BST thin-films by XRD analysis. In measurement result, this capacitors showed a dielectric constant of about 200 at 1MHz and leakage current density of 5$\times$10$^{-8}$ A/$\textrm{cm}^2$ at 1.5V Microstructure of BST thin-films exhibited effective quality in low-temperature annealed 71ms than high-temperature annealed 71ms.s.s.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.383-386
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• 2004

DC accelerated aging characteristics of Zn-Pr-Co-Cr-La oxides-based varistors were investigated with various sintering temperatures. The varistors sintered at $1240^{\circ}C$ exhibited the highest nonlinearity, with a nonlinear exponent of 79.3 and a leakage current of $0.3\;{\mu}A$, whereas completely degraded because of thermal runaway owing to low sintered density. The varistors sintered at $1250^{\circ}C$ exhibited not only a high nonlinearity with the nonlinear exponent 61.4 and the leakage current 0.7 ${\mu}A$, but also a high stability with the variation rates of varistor voltage and nonlinear exponent are -1.01% and -10.67%, respectively, under DC stress condition such as $(0.85\;V_{1mA}/115^{\circ}C/24\;h)+(0.90\;V_{1mA}/120^{\circ}C/24\;h)+(0.95\;V_{1mA}/125^{\circ}C/24\;h)+(0.95\;V_{1mA}/150^{\circ}C/24\;h)$.

• Journal of Power Electronics
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• 제19권5호
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• pp.1087-1098
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• 2019

In this paper, a detuning factor (DeFac) method is proposed to design the key parameters for optimizing the transfer power and efficiency of an Inductively Coupled Power Transfer (ICPT) system with primary-secondary side compensation. Depending on the robustness of the system, the DeFac method can guarantee the stability of the transfer power and efficiency of an ICPT system within a certain range of resistive-capacitive or resistive-inductive loads. A MATLAB-Simulink model of a ICPT system was built to assess the system's main evaluation criteria, namely its maximum power ratio (PR) and efficiency, in terms of different approaches. In addition, a magnetic field simulation model was built using Ansoft to specify the leakage flux and current density. Simulation results show that both the maximum PR and efficiency of the ICPT system can reach almost 70% despite the severe detuning imposed by the DeFac method. The system also exhibited low levels of leakage flux and a high current density. Experimental results confirmed the validity and feasibility of an ICPT system using DeFac-designed parameters.

• 전력전자학회논문지
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• 제24권4호
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• pp.279-285
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• 2019

This study proposes an enhanced switching pattern that can improve energy transfer efficiency in an active cell-balancing circuit using a multiwinding transformer. This balancing circuit performs cell balancing by transferring energy stored in a specific cell with high energy to another cell containing low energy through a multiwinding transformer. The circuit operates in flyback and buck-boost modes in accordance with the energy transfer path. In the conventional flyback mode, the leakage inductance of the transformer and the stray inductance component of winding can transfer energy to an undesired path during the balancing operation. This case results in cell imbalance during the cell-balancing process, which reduces the energy transfer efficiency. An enhanced switching pattern that can effectively perform cell balancing by minimizing the amount of energy transferred to the nontarget cells due to the leakage inductance components in the flyback mode is proposed. Energy transfer efficiency and balancing speed can be significantly improved using the proposed switching pattern compared with that using the conventional switching pattern. The performance improvements are verified by experiments using a 1 W prototype cell-balancing circuit.

• Smart Structures and Systems
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• 제28권6호
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• pp.727-735
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• 2021

Recently, non-destructive health monitoring methods such as magnetic flux leakage (MFL) method, have become popular due to their advantages over destructive methods. Currently, numerical study on this field has been limited to simplified studies by only obtaining MFL instead of induced voltage inside coil sensor. In this study, it was proposed to perform a novel numerical simulation of MFL's coil sensor by considering vital parameters including specimen's motion with constant velocity and saturation status of specimen in time domain. A steel-rod specimen with two stepwise cross-sectional changes (i.e., 21% and 16%) was fabricated using low carbon steel. In order to evaluate the results of numerical simulation, an experimental test was also conducted using a magnetic probe, with same size specimen and test parameters, exclusively. According to comparative results of numerical simulation and experimental test, similar signal amplitude and signal pattern were observed. Thus, proposed numerical simulation method can be used as a reliable source to check efficiency of sensor probe when different size specimens with different defects should be inspected.

• 방사성폐기물학회지
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• 제21권4호
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• pp.465-479
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• 2023

To ensure the safety of disposal facilities for radioactive waste, it is essential to quantitatively evaluate the performance of the waste disposal facilities by using safety assessment models. This paper addresses the development of the safety assessment model for the underground silo of Wolseong Low-and Immediate-Level Waste (LILW) disposal facility in Korea. As the simulated result, the nuclides diffused from the waste were kept inside the silo without the leakage of those while the integrity of the concrete is maintained. After the degradation of concrete, radionuclides migrate in the same direction as the groundwater flow by mainly advection mechanism. The release of radionuclides has a positive linear relationship with a half-life in the range of medium half-life. Additionally, the solidified waste form delays and reduces the migration of radionuclides through the interaction between the nuclides and the solidified medium. Herein, the phenomenon of this delay was implemented with the mass transfer coefficient of the flux node at numerical modeling. The solidification effects, which are delaying and reducing the leakage of nuclides, were maintained the integrity of the nuclides. This effect was decreased by increasing the half-life and the mass transfer coefficient of radionuclides.

• 한국전자파학회논문지
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• 제24권11호
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• pp.1091-1097
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• 2013

이 논문은 $0.11{\mu}m$ RF CMOS 공정에서 비대칭 몸체 바이어싱을 적용한 비교기를 사용한 정류기를 제안한다. 제안하는 정류기는 MOSFET와 두 개의 비교기로 이루어져 있다. 이 비교기는 부하 전압이 입력 전압보다 높을 때 생기는 역방향 누설 전류를 줄이는 데 사용한다. 비대칭 몸체 바이어싱을 사용함으로써 비교기의 High에서 Low 상태로 바꾸는 기준 전압을 높이고, 누설 전류가 흐르는 시간을 줄인다. 13.56 MHz의 2 Vpp 교류전압을 입력하고, $1k{\Omega}$의 저항과 1 nF의 커패시터를 부하에 연결한 환경에서 측정하였다. 시뮬레이션 결과, 전압 변환 효율은 87.5 %, 전력 변환 효율은 45 %이고, 측정한 전압 변환 효율은 85.215 %, 전력 변환 효율은 50 %이다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제10권4호
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• pp.265-275
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• 2010

In this work, reliable methodology for device design is presented. Based on this method, the underlap length has been optimized for minimizing the gateinduced drain leakage (GIDL) in a 22-nm node 4-terminal (4-T) silicon-on-insulator (SOI) fin-shaped field effect transistor (FinFET) by TCAD simulation. In order to examine the effects of underlap length on GIDL more realistically, doping profile of the source and drain (S/D) junctions, carrier lifetimes, and the parameters for a band-to-band tunneling (BTBT) model have been experimentally extracted from the devices of 90-nm channel length as well as pnjunction test element groups (TEGs). It was confirmed that the underlap length should be near 15 nm to suppress GIDL effectively for reliable low standby power (LSTP) operation.

• Environmental Analysis Health and Toxicology
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• 제9권1_2호
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• pp.25-35
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• 1994

Many nephrotoxic agents exert their effect primarily on the cells of the proximal tubules. We used the LLC-$PK_1$, kidney epithelial cell line as a model system for studies on nephrotoxicity and investigated whether the uptake of $\alpha$-methylglucose($\alpha$-MG) could serve as a parameter to assess effects of nephrotoxicants on the functional integrity of the cells at an early time of toxicity. The enzyme leakage test which has been used to be as a conventional cytotoxic parameter in vitro, was conducted to compare with $\alpha$-MG uptake. Treatment with cisplatin for 24 and 48 hours significantly increased activities of lactate dehydrogenase and $\gamma$-glutamyltransferase in culture medium at a concentration of 50$\mu$M. However, above 100$\mu$M of concentration, activities of these enzymes in media were dramatically decreased by cisplatin. These observations indicate that cisplatin has direct inhibitory effect on the activities of these enzymes and make it doutful to use enzyme leakage test to demonstrate damage of kidney cells by chemicals such as cisplatin over the appropriate range of concentration. Cisplatin inhibited $\alpha$-MG uptake at a low concentration which enzymes were not leaked. Also cadmium chloride and mercuric chloride which are acutely nephrotoxic in vivo, significantly inhibited $\alpha$-MG uptake at a low concentration. These results indicate that the uptake of $\alpha$-methylglucose in LLC-$PK_1$cell line is a useful biomarker for the study of nephrotoxicity.

• Journal of Korean Neurosurgical Society
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• 제38권4호
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• pp.259-264
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• 2005

Objective : The vertebroplasty is an excellent procedure in spine compression fracture, but there are some problems such as cement leakage and difficulties in bone biopsy. Recently, the osteoplasty system is developed to solve these problems, so we will report the usefulness of the osteoplasty system. Methods : From January 2003 to November 2003, there are 9patients with simple osteoporotic spine compression fracture, 2 compression fracture patients combined with suspicious spinal metastasis, 1patient with suspicious primary bone tumor, and 2patient with infection on spine. All patients were treated using the osteoplasty system. Results : All 11 compression fracture patients were relived the back pain after the osteoplasty and there is no complication. The bone biopsies in 3 suspicious cancer patients were also effectively performed using the osteoplasty system; negative result in 2patients and positive result in 1patient. The culture result of spontaneous discitis was no growth for 48hours. The spine tuberculosis was confirm using the osteoplasty system. Conclusion : The osteoplasty system has distinguished advantages in comparison with the vertebroplasty. That is, the risk of cement leakage is lower than vertebroplasty because of low pressure delivery system. And we can obtain the specimen effectively in bone biopsy because of large cannula. In conclusion, we emphasize that the osteoplasty system is a more useful procedure in spine compression fracture especially in the patient needed bone biopsy for diagnosis.