• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.4
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• pp.27-32
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• 2005

Liquid valve is divided into cylinder and liquid part or composed of a single body structure. It becomes a connected structure to cylinder head after inserting stainless(STS) shaft to Teflon packing. In injecting and intercepting fluid, working efficiency becomes low because of the top and bottom round trip operation the friction between Teflon packing and STS shaft fluid leakage, decline of working environment, and each part replacement. And so target value is unattainable in productivity liquid valve design, quality, and structure change are studied. In this paper, designed to solve the existing problems basically, to prevent friction of Piston by developing diaphragm linked with piston, to satisfy long life, and to provide the prevention of leakage. The objective of the study is also to prevent remains fluid at nozzle tip after dispensing fluid, and bell close with the suction function in piston retreating.

• Korean Journal of Materials Research
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• v.5 no.7
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• pp.816-819
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• 1995

(Ba$_{1-x}$ , Sr$_{x}$)TiO/$_3$thin films on Pt/Ti/SiO$_2$/Si substrates were prepared by LP MOCVD(Low Pressure Metal-Organic Chemical Vapor Deposition). The crystalinity of BST deposit had a (100) preferred orientation with increasing deposition temperature due to surface diffusion. BST films deposited at 90$0^{\circ}C$ showed a dielectric constant of 365 and a dissipation factor of 0.052 at a frequency of 100kHz. The chance of capacitance of the films with applied voltage was small, showing paraelectric properties. BST film deposited at 90$0^{\circ}C$ had a charge storage density of 60 fc/${\mu}{\textrm}{m}$$^2$at a field of 0.2MV/cm and the leakage current density of 20 nA/$\textrm{cm}^2$ at a field of 0.15 MV/cm.cm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.83-87
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• 2002

Plasma enhanced chemical vapor deposited (PECVD) silicon nitride ($SiN_X$) is widely used as a gate dielectric material for the hydrogenated amorphous silicon(a-Si:H) thin film transistors (TFT's). We investigated $SiN_X$ films were deposited PECVD at low temperature ($300^{\circ}C$). The reaction gases were used pure nitrogen and a helium diluted of silane gas(20% $SiH_4$, 80% He). Experimental investigations were carried out with the variation of $N_2/SiH_4$ flow ratios from 3 to 50 and the rf power of 200 W. This article presents the $SiN_X$ gate dielectric studies in terms of deposition rate, hydrogen content, etch rate and C-V, leakage current density characteristics for the gate dielectric layer of thin film transistor applications. Electrical properties were analyzed through high frequency (1MHz) C-V and current-voltage (I-V) measurements. The thickness and the refractive index on the films were measured by ellipsometry and chemical bonds were determined by using an FT-IR equipment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12C
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• pp.1175-1187
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• 2007

This paper proposes a novel crest factor reduction (CFR) algorithm to be deployed on WCDMA basestation. Generally speaking, it is well described that the reduction of peak-to-average ratio (PAR) yields the possibility of using low cost power amplifier such that the basesation becomes economic However, the simple reduction of PAR could degrade the signal quality measured by either peak code domain error (PCDE) or error vector measurement (EVM), and the level of channel interference constrained by adjacent channel leakage ratio (ACLR). Regarding these imperfections, this paper introduces an effective CFR algorithm in which the function of filter-dependent CFR (FDCFR) incorporated with the histogram-based waterfilling code domain compensation (HBWCDC) carries out. To verify the performance of the proposed CFR technique, substantial simulations including comparative works are conducted with obeying W-CDMA basestation verification specification. To exploit the superiority, the performance of the proposed method is tentatively compared with that associated to the simple memoryless clipping method and the memory-required filter-dependent clipping method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.5
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• pp.362-369
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• 2001

The electrical properties of varistors consisting of Zn-Pr-Co-Cr-Er oxides were investigated in the Er$_2$O$_3$content range of 0.0 to 2.0 mol%. the varistors without Er$_2$O$_3$ exhibited a relatively low nonlinearity, which was 14.24 in the nonlinear exponent and 21.47 $\mu$A in the leakage current. However, the varistors with Er$_2$O$_3$ sintered at 1335$^{\circ}C$ for 1h exhibited very high nonlinear exponent of 70, in particular, reaching a maximum value of 78.05 in 2.0 mol% Er$_2$O$_3$, and those sintered at 1335$^{\circ}C$ for 2h exhibited the nonlinear exponent close to 50, in particular, reaching a maximum value of52.76 in 0.5 mol% Er$_2$O$_3$. The others except for 0.5 mol% Er$_2$O$_3$-added varistors exhibited very high instability resulting in a thermal runaway within a short time, even a weak DC stress. Increasing soaking time decreased the nonlinearity, but increased the stability. The varistors containing 0.5mol% Er$_2$O$_3$ sintered for 2h exhibited excellent stability, in which the variation rate of the varistor voltage and nonlinear exponent was -1.70% and -7.15%, respectively, under more severe DC stress such as (0.80 V$_{1mA}$/9$0^{\circ}C$/12h)+(0.85 V$_{1mA}$/115$^{\circ}C$/12h)+(0.90 V$_{1mA}$/12$0^{\circ}C$/12h)+(0.95 V$_{1mA}$/1$25^{\circ}C$/12h)+(0.95 V$_{1mA}$/15$0^{\circ}C$/12h).TEX>/12h).

• The Korean Journal of Pain
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• v.19 no.2
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• pp.261-265
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• 2006

A vertebral compression fracture can cause chronic back pain, and may also result in progressive kyphosis. The traditional treatments of a vertebral compression fracture include bed rest, analgesics and bracing. Balloon kyphoplasty can restore the vertebral height and allow safe bone cement injection into the cavity made by the balloon, which significantly reduces the risk of cement leakage compared to vertebroplasty. An 82-year-old female patient suffered from severe low back pain. Due to the intractable pain and immobility, which could not be relieved by conventional care, as well as the empty vertebral body associated with communicated fractures of the vertebral surfaces, balloon kyphoplasty, with a thicker bone cement injection than usual with balloon kyphoplasty, was chosen. The preoperative intractable pain and immobility were dramatically relieved soon after the procedure, without any complications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12A
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• pp.2002-2007
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• 1999

In this paper, the n-channel poly-Si thin-film transistors (poly-Si TFT's) formed by solid phase crystallization (SPC) on glass were investigated by measuring the electrical properties of poly-Si films, such as I-V characteristics, mobility, leakage current, threshold voltage, and subthreshold slope. It is done to decide to be applied on TFT-LCD with large-size and high density. In n-channel poly-Si TFT with 2, 10, 25$\mu\textrm{m}$ of channel length, the field effect mobilities are 111, 126 and 125 $\textrm{cm}^2$/V-s and leakage currents are 0.6, 0.1, and 0.02 pA/$\mu\textrm{m}$, respectively. Low threshold voltage and subthreshold slope, and good ON-OFF ratio are shown, as well. Thus, the poly-Si TFT’s used by SPC are expected to be applied on TFT-LCD with large-size and high density, which can integrate display panel and peripheral circuit on a large glass substrate.

• Journal of Chest Surgery
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• v.16 no.4
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• pp.498-505
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• 1983

It has been over 20 years since successful operations of Cardiac valves at the Department of Thoracic and Cardiovascular surgery, college of medicine, Yonsei University. About six hundreds of patients with severely symptomatic valvular heart disease have had valve operations with complete loss or sharp decrease in their cardiac symptoms since 1956. As the number of cardiac patient increases, reoperation on valves assumes greater importance. To define the group of patients undergoing reoperations on valves and the factors influencing their survival, we have reviewed our experiences of the reoperation on valves at the Yonsei University, Severance Hospital. This is a report of 29 cases which was undergone secondary or more surgery for valvular heart disease from 1966 to 1983. The primary operations includes 159 cases of open heart surgery from 1966 to 1975 and 476 cases from 1976 to march, 1983. The secondary operations are classified into groups of secondary valvuloplasty or valvotomy [8 cases], prosthetic valve replacement following valvuloplasty or valvotomy [14 cases] and prosthetic valve rereplacement [2 case] for such as calcification, degeneration and perforation of the cusps and paravalvular leakage, of the bioprosthetic valves. The leading indication for reoperation of mitral valve was restenosis or stenoinsufficiency, The indications of aortic valve replacement was active bacterial endocarditis, medically uncontrollable prosthetic endocarditis or paravalvular leakage. Overall death rate of the reoperation was 17.4% [5 death among the 29 patients] and the leading causes of death were myocardial failure, arrhythmia, cerebral embolism, acute renal failure due to low output syndrome. And it was followed by sepsis associated with active prosthetic endocarditis. The death rate of reoperation was 4.3% in the elective cases except urgent cases and the death rate of overall cardiac valve except reoperation cases was 4.1% in the last two years. Although the general mortality of reoperation was high, both mortality rates were comparable except emergency cases due to urgent preoperative patient’s condition.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1768-1789
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• 2015

The maximal signal-to-interference-plus-noise ratio (Max-SINR) algorithm for interference alignment (IA) has received considerable attention for its high sum rate achievement in the multiple-input multiple-output (MIMO) interference channel. However, its complexity may increase dramatically when the number of users approaches the IA feasibility bound, and the number of iterations and computational time may become unacceptable. In this paper, we study the properties of the Max-SINR algorithm thoroughly by presenting theoretical insight into the algorithm and by providing the potential of reducing the overall computational cost. Furthermore, a novel IA algorithm based on the principle direction search is proposed, which can converge more rapidly than the conventional Max-SINR method. In the proposed algorithm, it searches along the principle direction, which is found to approximately point to the convergence values, and can approach the convergence solutions rapidly. In addition, the closed-form solution of the optimal step size can be formulated in the sense of minimal interference leakage. Simulation results demonstrate that the proposed algorithm outperforms the conventional minimal interference leakage and Max-SINR algorithms in terms of the convergence rate while guaranteeing the high throughput of IA networks.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.1
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• pp.39-45
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• 2003

The varistor properties of ZnO-Pr$_{6}$O$_{11}$-CoO-based ceramics doped with Sm$_2$O$_3$were investigated in the addition range of 0.0~2.0 mol% Sm$_2$O$_3$at sintering temperature of 130$0^{\circ}C$ and 135$0^{\circ}C$. As Sm$_2$O$_3$ content is increased, the breakdown voltage was increased in the range of 348.9~521.8 V/mm for ceramics sintered at 130$0^{\circ}C$ and 8.5~381.3 V/mm for ceramics sintered at 135$0^{\circ}C$. On the whole, the increase of sintering temperature led to the low nonlinearity regardless of Sm$_2$O$_3$content. ZnO-Pr$_{6}$O$_{11}$-CoO-based ceramics doped with 1.0 mol% at each sintering temperature exhibited the most superior varistor properties, with the nonlinear exponent of 42.1 at 130$0^{\circ}C$, 36.8 at 135$0^{\circ}C$ and the leakage current of 9.2 $\mu$A at 130$0^{\circ}C$, 11.7 $\mu$A at 135$0^{\circ}C$.EX>.EX>.