• Journal of Korean Neurosurgical Society
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• v.45 no.1
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• pp.16-23
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• 2009

Objective : This retrospective study of 215 patients with 383 symptomatic osteoporotic vertebral compression fractures (VCFs) treated by percutaneous vertebroplasty (PVP), was performed to evaluate the clinical outcomes, and to analyze the various clinical factors affecting these results. Methods : The authors assessed the clinical outcome under the criteria such as the pain improvement, activity, requirement of analgesics, and the patient's satisfaction, and determined the relation to various peri- and intra-operative factors, and postoperative imaging findings. Results : The outcome was determined as 84.2% in relief of pain, 72.0% in change in activity, 65.7% in analgesics use, and 84.7% of satisfaction rate. More severe focal back pain, high uptake bone scan, and the lower mean T-score were related to the better pain relief following PVP. The longer the duration between fracture and PVP, the less severe focal back pain, low uptake bone scan, and leakage of PMMA into the paravertebral space were related to the less improvement in activity. Female and low uptake bone scan showed a correlation with more analgesic use. The longer the duration between fracture and PVP, low uptake bone scan, and the higher the mean T-score were correlated with the less the patients satisfaction. Conclusion : Our study suggests that PVP may be more effective in the acute phase of VCFs, more severe focal pain, and far advanced osteoporosis on BMD. Leakage of PMMA into the paravertebral spcae also could be affecting the surgical results.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.11
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• pp.1-11
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• 1997

The transient current components of the dRAM are analyzed and the sensing current, data path operation current and DC leakage current are revealed to be the major curretn components. It is expected that the supply voltage of less than 1.5V with low VT MOS witll be used in multi-giga bit dRAM. A low voltage dual VT self-timed CMOS logic in which the subthreshold leakage current path is blocked by a large high-VT MOS is proposed. An active signal at each node of the nature speeds up the signal propagation and enables the synchronous DRAM to adopt a fast pipelining scheme. The sensing current can be reduced by adopting 8 bit prefetch scheme with 1.2V VDD. Although the total cycle time for the sequential 8 bit read is the same as that of the 3.3V conventional DRAM, the sensing current is loered to 0.7mA or less than 2.3% of the current of 3.3V conventional DRAM. 4 stage pipeline scheme is used to rduce the power consumption in the 4 giga bit DRAM data path of which length and RC delay amount to 3 cm and 23.3ns, respectively. A simple wave pipeline scheme is used in the data path where 4 sequential data pulses of 5 ns width are concurrently transferred. With the reduction of the supply voltage from 3.3V to 1.2V, the operation current is lowered from 22mA to 2.5mA while the operation speed is enhanced more than 4 times with 6 ns cycle time.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.6
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• pp.44-51
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• 1999

The electrical conduction mechanism of high dielectric $(Ba,Sr)TiO_3$ (BST) thin film capacitor, which is the promising cell capacitor for high density DRAM, was investigated in low field region (<0.2MV/cm). It is known that the current in the low field region consists of dielectric relaxation current and leakage current. The current-time (I-t) measurement technique under the constant voltage was used for extracting successfully each current component. The conduction mechanism of the BST capacitor was deduced from the dependency of the current on the measurement temperature, strength of electric field, the polarity of applied electric field and post annealing process. From these results, it was suggested that the dielectric relaxation current and the leakage current are originated from the redistribution of internally trapped electron by hopping process and Pool-Frenkel conduction mechanism, respectively. It was also concluded that traps causing these two current components are due to oxygen vacancies within the BST film.

• Korean Journal of Materials Research
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• v.30 no.10
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• pp.502-508
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• 2020

This paper focuses on the electrical properties and stability against DC accelerated aging stress of ZnO-V₂O₅-MnO₂-Nb₂O₅-Bi₂O₃-Co₃O₄-Dy₂O₃ (ZVMNBCD) varistor ceramics sintered at 850 - 925 ℃. With the increase of sintering temperature, the average grain size increases from 4.4 to 11.8 mm, and the density of the sintered pellets decreases from 5.53 to 5.40 g/㎤ due to the volatility of V₂O₅, which has a low melting point. The breakdown field abruptly decreases from 8016 to 1,715 V/cm with the increase of the sintering temperature. The maximum non-ohmic coefficient (59) is obtained when the sample is sintered at 875 ℃. The samples sintered at below 900 ℃ exhibit a relatively low leakage current, less than 60 mA/㎠. The apparent dielectric constant increases due to the increase of the average grain size with the increase of the sintering temperature. The change tendency of dissipation factor at 1 kHz according to the sintering temperature coincides with the tendency of the leakage current. In terms of stability, the samples sintered at 900 ℃ exhibit both high non-ohmic coefficient (45) and excellent stability, 0.8% in 𝚫E_B/E_B and -0.7 % in 𝚫α/α after application of DC accelerated aging stress (0.85 E_B/85 ℃/24 h).

• Journal of IKEEE
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• v.24 no.3
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• pp.828-837
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• 2020

This paper presents the optimal design of planar flyback transformer suitable for small-size and low-profile of AC to DC adapter for 10W tablet. This paper also proposes the injection winding transformer of Hybrid and Drum types capable of the winding method of automatic type and the reduction of transformer size and leakage inductance(L_k) compared to the conventional mass-production flyback transformer with the winding method of manual type. In particular, the injection winding transformer of Drum type proposed in this paper is constructed in a horizontal laying of its transformer to solve the connection problem of copper plate injection winding on the secondary side of the one of Hybrid type. The primary and secondary windings of the injection winding transformer of Hybrid and Drum types used the conventional winding and the copper plate injection winding, respectively. For the injection winding transformer of Hybrid and Drum types proposed in this paper, the optimal design of planar flyback transformer suitable for small-size and low-profile was carried out using Maxwell 2D and 3D tool.

• Korean Journal of Environmental Agriculture
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• v.19 no.1
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• pp.58-61
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• 2000

This study was conducted to determine the effect of low dose ${\gamma}-ray$ on the germination rate and physiology of germinative seeds of welsh onion ( Allicm fistulosum L. cv. Sukchangwoidae ) and spinach ( Spinacia oleracea L. cv. Chungrok ). The germination rate of irradiation group was much higher than that of the control. Especially it was noticeably higher in 1 or 2 Gy irradiation groups in the sowing spinach seeds on paper towel. On the welsh onion, the germination rate of the 1 Gy irradiation group increased by 17% compared to that of the control. Ion leakage from seeds irradiated with low dose of ${\gamma}-ray$ was decreased compared to that from the control especially at the early stage of incubation when examined by means of electric conductance. This tendency was confirmed in seeds of welsh onion and spinach. Starch hydrolysis was stimulated by ${\gamma}-ray$ irradiation in welsh onion. Furthermore ${\gamma}-ray$ irradiation was beneficial to keeping the vitality of seeds as determined through decarboxylation of glutamic acid.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.4
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• pp.495-502
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• 2014

Fast recovery diodes (FRDs) were developed using the $p^{{+}{+}}/n^-/n^{{+}{+}}$ epitaxial layers grown by low temperature epitaxy technology. We investigated the effect of electrostatic discharge (ESD) stresses on their electrical and switching properties using current-voltage (I-V) and reverse recovery time analyses. The FRDs presented a high breakdown voltage, >450 V, and a low reverse leakage current, < $10^{-9}$ A. From the temperature dependence of thermal activation energy, the reverse leakage current was dominated by thermal generation-recombination and diffusion, respectively, at low and high temperature regions. By virtue of the abrupt junction and the Pt drive-in for the controlling of carrier lifetime, the soft reverse recovery behavior could be obtained along with a well-controlled reverse recovery time of 21.12 ns. The FRDs exhibited excellent ESD robustness with negligible degradations in the I-V and the reverse recovery characteristics up to ${\pm}5.5$ kV of HBM and ${\pm}3.5$ kV of IEC61000-4-2 shocks. Likewise, transmission line pulse (TLP) analysis reveals that the FRDs can handle the maximum peak pulse current, $I_{pp,max}$, up to 30 A in the forward mode and down to - 24 A in the reverse mode. The robust ESD property can improve the long term reliability of various power applications such as automobile and switching mode power supply.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.6
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• pp.504-511
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• 2003

In this paper, inverter type neon power supply using a piezoelectric transformer is fabricated and its characteristic is investigated. Developed neon power supply is composed of basic circuit and blocks, such as rectifier part, frequency oscillation part and piezoelectric transformer and resonant half bridge inverters. In this paper for complement the low power limitation, piezoelectric transformer at parallel connected driving by inverter is studied for noon tubes system of high power. When piezoelectric transformer is connected with parallel, LC filter connection method with parallel and selection of inductance L and capacitor C of primary side is suggested for reduce unbalanced current at the terminal of each transformer. Piezoelectric transformers use piezoelectric ceramic devices. Thus it is wireless therefore it has high power density, high Isolation level, low loss, more light, and miniaturization. In addition, high voltage transfer ratio is expected because there is no leakage inductance. Also, it has economic merit that the electrical loss Is low because structure is simple, small and tighter weight.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.6
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• pp.797-801
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• 2014

This research presented the concept of employing the punch-through diode triggered SCRs (PTTSCR) for low voltage ESD applications such as transient voltage suppression (TVS) devices. In order to demonstrate the better electrical properties, various traditional ESD protection devices, including a silicon controlled rectifier (SCR) and Zener diode, were simulated and analyzed by using the TCAD simulation software. The simulation result demonstrates that the novel PTTSCR device has better performance in responding to ESD properties, including DC dynamic resistance and capacitance, compared to SCR and Zener diode. Furthermore, the proposed PTTSCR device has a low reverse leakage current that is below $10^{-12}$ A, a low capacitance of $0.07fF/mm^2$, and low triggering voltage of 8.5 V at $5.6{\times}10^{-5}$ A. The typical properties couple with the holding voltage of 4.8 V, while the novel PTTSCR device is compatible for protecting the low voltage, high speed ESD protection applications. It proves to be good candidates as ultra-low capacitance TVS devices.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1239-1241
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• 1995

The different hydrogen passivation effects on low-temperature processed and high-temperature processed poly-Si thin film transistors have been investigated. The hydrogen passivation on low-temperature processed poly-Si TFT results in the increase of the field-effect mobility and the decrease or the threshold voltage, while the hydrogenation increases the field-effect mobility and decreases the leakage current in high-temperature processed poly-Si TFT. The effective trap state densities of low-temperature processed poly-Si TFT before and after 5 hours of hydrogenation are estimated at about $4.0{\times}10^{12}/cm^2$ and $1.5{\times}10^{12}/cm^2$, while those of high-temperature processed poly-Si TFT are about $1.5{\times}10^{12}/cm^2$ and $1.2{\times}10^{12}/cm^2$, respectively.