• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.6
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• pp.486-494
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• 2012

In this paper, we proposes the three-phase embedded Z-source inverter consisting of the three embedded Z-source converters and it's the output voltage control method. Each embedded Z-source converter can produce the bipolar output capacitor voltages according to duty ratio D such as single-phase PWM inverter. The output AC voltage of the proposed system is obtained as the difference in the output capacitor voltages of each converter, and the L-C output filter is not required. Because the output AC voltage can be stepped up and down, the boost DC converter in the conventional two-stage inverter is unnecessary. To confirm the validity of the proposed system, PSIM simulation and a DSP based experiment were performed under the condition of the input DC voltage 38V, load $100{\Omega}$, and switching frequency 30kHz. Each converter is connected by Y-connection for three-phase loads. In case that the output phase voltage is the same $38V_{peak}$ as the input DC voltage and is the 1.5 times($57V_{peak}$), the simulation and experimental results ; capacitor voltages, output phase voltages, output line voltages, inductor currents, and switch voltages were verified and discussed.

• BMB Reports
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• v.29 no.1
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• pp.32-37
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• 1996

The cysteine 43, potentially important in the activity of O-acetylserine sulfhydrylase (OASS) from Salmonella typhimurium, has been changed to serine. This mutant enzyme (C43S) has been studied in order to gain insight into the structural basis for the binding of inhibitor, substrate and product. UV-visible spectra of C43S exhibit the same spectral change in the presence of OAS as that observed with wild type enzyme, indicating C43S will form an ${\alpha}$-aminoacrylate Schiff base intermediate. At pH 6.5, however, the deacetylase activity of C43S is much higher than wild type enzyme indicating that cysteine 43 plays a role in stabilizing the ${\alpha}$-aminoacrylate intermediate. The fluoroscence spectrum of C43S exhibits a ratio of emission at 340 to 502 nm of 16.9, reflecting the lower fluorescence of PLP and indicating that the orientation of cofactor and tryptophan are different from that of the wild type enzyme. The emission spectrum of C43S in the presence of OAS gives two maxima at 340 and 535 nm. The 535 nm emission is attributed to the fluoroscence of the ${\alpha}$-aminoacrylate intermediate. The visible circular dichroic spectrum was similar to wild type enzyme, but the negative effect observed at 530~550 nm and the molar ellipicity values for the mutant are decreased by about 50% compared to wild type enzyme. The circular dichroic and fluoroscence studies suggest binding of the cofactor is less asymmetric in C43S than in the wild type enzyme.

• Journal of the Korean Chemical Society
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• v.23 no.3
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• pp.132-135
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• 1979

The thermal decomposition of a dilute mixture of 1,1,2,2,-$C_2H_2F_4$ in argon has been investigated in a single-pulse shock tube between 1146 and $1232^{\circ}K$ at total reflected shock pressures of about 3000 torr. Under these conditions the reaction proceeds exclusively by the molecular elimination of hydrogen fluoride. It has been found that the asymmetric isomer with the fully fluorinated ${\alpha}$-carbon requires the higher activation energy which may be attributed to the difference in atomic charge densities between isomers. The rate constant ratio is given by $log(k_1/k_2) = -0.069 {\pm} 0.021 ＋(1388{\pm}113) / 2.303RT$ in good agreement with previous independent studies.

• Journal of Sensor Science and Technology
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• v.13 no.2
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• pp.101-109
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• 2004

This paper presents a novel z-axis accelerometer with perfectly aligned vertical combs fabricated using the extended sacrificial bulk micromachining (extended SBM) process. The z-axis accelerometer is fabricated using only one (111) SOI wafer and two photo masks without wafer bonding or CMP processes as used by other research efforts that involve vertical combs. In our process, there is no misalignment in lateral gap between the upper and lower comb electrodes, because all critical dimensions including lateral gaps are defined using only one mask. The fabricated accelerometer has the structure thickness of $30{\mu}m$, the vertical offset of $12{\mu}m$, and lateral gap between electrodes of $4{\mu}m$. Torsional springs and asymmetric proof mass produce a vertical displacement when an external z-axis acceleration is applied, and capacitance change due to the vertical displacement of the comb is detected by charge-to-voltage converter. The signal-to-noise ratio of the modulated and demodulated output signal is 80 dB and 76.5 dB, respectively. The noise equivalent input acceleration resolution of the modulated and demodulated output signal is calculated to be $500{\mu}g$ and $748{\mu}g$. The scale factor and linearity of the accelerometer are measured to be 1.1 mV/g and 1.18% FSO, respectively.

• Journal of Korean Society of Steel Construction
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• v.23 no.1
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• pp.125-135
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• 2011

To obtain a lower story height with a long span and better fire resistance, a new composite floor system using GFRP (glass-fiber-reinforced plastics) was proposed. This floor system consists of asymmetric steel with a web opening, a hollow core ball, concrete, and GFRP. To evaluate the flexural performance of the new composite floor system, an experiment was conducted. The test parameters were the presence of GFRP, the void ratio in relation to the hollow core balls, and the web opening. The test results showed that the resistance and stiffness of the specimen with GFRP were 10% higher than those of the reference specimen, and that fully composite action was accomplished up to the yielding point. After the attainment of the yield strength, the ductility of the specimen was reduced due to the stress concentration around the web openings. The slip between the concrete and steel beam, however, was small. Thus, in the design of the proposed new floor systems, it is desirable that the calculated resistance be reduced by 15%, for safety.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.7
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• pp.3325-3328
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• 2016

Background: There are limited studies on oncoplastic breast conserving surgery in Asian women. We aimed to determine the applicability and safety of oncoplastic surgery, highlighting the specific circumstances when it will be most useful and compare our preferred technique with the worldwide practice of oncoplastic approaches. Materials and Methods: Breast cancer patients who underwent oncoplastic breast conserving surgery at a single institution from 1st May 2014-31st March 2015 were included. Data on patient demographics, tumor characteristics and the type of oncoplastic surgery performed were collected. Results: Nineteen breast cancer patients were identified. 42.1% of patients had grade I ptosis. The indications for surgery included a large tumor to breast size ratio (52.6%), multifocal/multicentric lesions (36.8%) and asymmetric breasts (10.6%), averting a mastectomy in 89.4%. Round block was the commonest technique in 63% of patients, in contrast to the inverted T pattern most frequently used in renowned institutions in the West. Mean and median tumor size and weight of specimen were 29.4/25mm (11 - 75mm) and 77g/64g (10 - 246g) respectively. Re-excision rate was 10.5%. Complete mastectomy was performed for one patient. One patient developed wound dehiscence which was treated conservatively. Cosmetic outcome was rated as excellent/good by 94.7% of patients. The patients remained clinically well after a median 16 months follow up. Conclusions: Oncoplastic breast conserving surgery is useful in a specific subgroup of Asian patients with a relatively small breast volume and minimal ptosis. Round block was the commonest technique in our series, in contrast to the worldwide utility of oncoplastic techniques. It is oncologically safe and has good cosmetic outcomes.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.9
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• pp.634-641
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• 2006

Flash memory has many advantages like non-volatility and fast I/O speed, but it has also disadvantages such as not-in-place-update data and asymmetric read/write/erase speed. For the performance of flash memory storage, it is essential for the buffer replacement algorithms to reduce the number of write operations that also affects the number of erase operations. A new buffer replacement algorithm is proposed in this paper, that delays the writes of not-cold-dirty pages in the buffer cache of flash storage. We show that this algorithm effectively decreases the number of write operations and erase operations without much degradation of hit ratio. As a result overall performance of flash I/O speed is improved.

• Korean Journal of Materials Research
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• v.13 no.4
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• pp.233-238
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• 2003

Ferromagnetic tunnel junctions, Ta/Cu/Ta/NiFe/Cu/$Mn_{75}$ $Ir_{25}$ $Co_{70}$ $Fe_{30}$/Al-oxide, were fabricated by do magnetron sputtering and plasma oxidation process. The effect of annealing temperature on the local transport properties of the ferromagnetic tunnel junctions was studied using contact-mode Atomic Force Microscopy (AFM). The current images reflected the distribution of the barrier height determined by local I-V analysis. The contrast of the current image became more homogeneous and smooth after annealing at $280^{\circ}C$. And the average barrier height $\phi_{ave}$ increased and its standard deviation $\sigma_{\phi}$ X decreased. For the cases of the annealing temperature more than $300^{\circ}C$, the contrast of the current image became large again. And the average barrier height $\phi_{ave}$ decreased and its standard deviation $\sigma_{\phi}$ increased. Also, the current histogram had a long tail in the high current region and became asymmetric. This result means the generation of the leakage current that is resulted from the local generation of a low barrier height region. In order to obtain the high tunnel magnetoresistance(TMR) ratio, the increase of the average barrier height and the decrease of the barrier height fluctuation must be strictly controlled.led.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.193-200
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• 2013

Recently, network coding has been actively studied to increase the spectral efficiency of two-way relay wireless channels such as cellular systems as well as broadcasting systems. In this paper, we derive the average transmission capacity and the outage probability of a network coding system, which utilizes two-way data transmission via the best relay rather than multiple relays. Since the data unbalance between the forward and the reverse link in two-way communication systems exists, we include the asymmetric link as well as the symmetric link in the analysis. It is noticed that the space diversity gain increases as the increase of the number of relays. Also we obtain 11.4 dB signal-to-noise ratio (SNR) gain with 9 relays compared to that with single relay in symmetrical link at the given conditions. In asymmetrical links, we denotes that the outage probability is more sensitive to the number of relays rather than data unbalance between the links.

• Journal of the Korean Chemical Society
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• v.39 no.9
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• pp.692-697
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• 1995

The chemical compositions and possible structure for the complex of B15C5 with Nd(Ⅲ) have been determined by NMR spectrophotometry in acetone-d6. On the stepwise additions of Nd(Ⅲ) to B15C5 solution of constant concentration, all the resonances shifted to downfield and the mole ratio of B15C5 to Nd(Ⅲ) was found to be 1 : 1. From the line broadening of proton peaks of NMR spectra, it was found that oxygen atoms in B15C5 interact with Nd(Ⅲ) ion. And in IR spectra of Nd(Ⅲ)-B15C5 complex, the band of asymmetric C-C-O stretching vibration shifted to a lower frequency region upon complexation. We have proposed the possible structure of the Nd(Ⅲ)-B15C5 coordinated with the five ether oxygen atoms and with the three bidentate nitrato groups.