• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.476-481
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• 1991

This paper investigates the relationship between the two problems, supervisor reduction and observation function (projection) design, which arise in supervisory control of DEDS. It is shown through an example that a reduced supervisor of minimal size does not necessarily result in a maximal projection when a projection design method which uses the transition structure of a supervisor is applied. Also, if an L-realizable projection P is available and if a supervisor has a special structural feature, a cover C for supervisor reduction can be easily obtained. By investigating the control-compatibility of states of the reduced supervisor based on C, we can also check maximality of P in a simple manner.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1058-1061
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• 2002

This paper presents the method of low power optimization considering the glitch reduction in CMOS circuits. Our algorithm utilizes the information of MOS size, the load capacitance of fan-out, and input slew to calculate the output waveform by using the linear signal model. Therefore, the accurate waveform of glitch can be obtained for estimation of power dissipation caused by glitches. Our algorithm is applied to ISCAS’85 benchmark circuits and experimental results show 23% glitch reduction and 11% total power reduction.

• Membrane Journal
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• v.22 no.5
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• pp.332-341
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• 2012

We studied the effects of induction of natural convection instability flow (NCIF) according to the gravitational orientation (inclined angle) of the membrane cell on the reduction of membrane fouling in the constant-flow ultrafiltration (UF) of colloidal silica solutions. Five colloidal silica solutions with different silica size (average size = 7, 12, 22, 50 nm and 78 nm) were used as UF test solutions. The silica particles in colloidal solutions form cakes on the membrane surface thereby causing severe membrane fouling. The constant-flow UF performance according to the gravitational orientation of the membrane cell (from $0^{\circ}$ to $180^{\circ}$ inclined angle), was examined in an unstirred dead-end cell. We evaluate the effects of NCIF on the suppression of fouling formation by measuring the variation of transmembrane pressure (TMP) and the increase of critical flux by using the flux-stepping method. In the constant-flow dead-end UF for the smaller size (7, 12 nm and 22 nm) silica colloidal solutions, changing the gravitational orientation (inclined angle) of the membrane cell above the $30^{\circ}$ angle induces NCIF in the membrane module. This induced NCIF enhances back transport of the deposited silica solutes away from the membrane surface, therefore gives for the reduction of TMP. But in the constant-flow UF for the more larger size (50 nm and 78 nm) silica colloidal solutions, NCIF effects are not appearing. The critical flux is increased as increasing the module angle and decreasing the silica size. Those results show that the intesity of NCIF occurrence in membrane module is more higher as increasing the module angle and decreasing the silica size.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.10-16
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• 2016

This work investigates the size and dispersion characteristics of silver nanoparticles synthesized by a liquid phase reduction method using PAA. The experimental variables were the molecular weight and doses of the PAA, reducing agent, dispersant, and organic solvent (ethanol-acetone). UV-visible spectrophotometer results confirm the formation of the silver particles, and SEM indicates size in the nanometer range. As the ultrasonication time increases, there is a tendency toward smaller agglomerates of nanoparticles. The agglomerates were dispersed into 1-5 agglomerates of particles by ultrasonication for 3 hours or more. Relatively spherical nanoparticles were produced with a completely homogeneous dispersion and size of 49.56-85.75 nm by ultrasonication using BYK-192, a dispersant containing copolymer with a pigment affinic group. The average size of the silver nanoparticles was increased to 36.82, 50.66, and 56.06 nm with increasing molecular weight of PAA. Also, the size of the nanoparticles increased with the capping of PAA on the surfaces of the nanoparticles when increasing the amount of PAA. The addition of hydrazine as a reducing agent produced relatively small particles because many nuclei were created by the reduction reaction. The ethanol-acetone solvent helped with the regular arrangement of the silver nanoparticles.

• Journal of Powder Materials
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• v.4 no.2
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• pp.106-112
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• 1997

$Cu-Al_20_3 $ composite powders were prepared by hydrogen reduction of $Cu^{2+}$ from ammoniacal copper sulfate solution on alumina core using autoclave. The copper reduction rate and the properties of copper layer were investigated using Scanning Electron Microscope(SEM), X-ray diffractometer, size and chemical analyzers. The reduction rate of $Cu^{2+}$ showed the maximum value when the molar ratio of [$NH_3$]/[$Cu^{2+}$] was 2. In order to prevent the agglomeration of Cu powder and ethane reduction rate, $Fe^{2+}$ and anthraquinone which act as catalysis were added in the solution. Catalysis was effectively chanced with the addition of two elemerts at a time. Optimum conditions obtained in this study were hydrogen reduction temperature of 205$^{\cire}C$, stirring speed of 500 rpm and hydrogen partial pressure of 300 psi. Obtained $Cu-Al_20_3 $ composite Powders were found to have the uniform and continuous copper coating layer of nodule shape with 3~5 $\mu$m thickness.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.137-142
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• 2004

The aim of this study is to investigate the characteristics and quantity of the noise reduction by floor coverings. The characteristics on the reduction of the lightweight impact sound level by floor coverings is as follows. The insulation level attained by floor coverings tends to be smaller in actual buildings than in public laboratories. The reduction of the impact sound level to the tape is similar to the method of adhesives. For this reason, the reduction of impact sound level by floor coverings in public laboratories can be utilized to tape. And the reduction of impact sound level by floor coverings is not influenced by the size of specimen except the specific frequency.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.3
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• pp.191-194
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• 2003

Macroglossia can cause dentomusculoskeletal deformities, instability of orthodontic and orthognathic surgical treatment, and create masticatory, speech and airway management problems. To determine whether a reduction glossectomy is necessary, it will important to identify the signs and symptoms of macroglossia. Development of dentoskeletal changes directly related with tongue size, such as an anterior open bite or a Angle Class III malocclusion tendency, would indicate that reduction glossectomy may be beneficial. For reduction glossectomy, several techniques have been reported. However, in most techniques the tip of tongue is removed. So its excision causes the loss of most mobile and sensitive portion of the tongue, and creates ankylosed, globular tongue. To avoid such problems, central tongue reduction technique have been proposed. This article will introduce central tongue reduction for anterior openbite case associated with macroglossia.

• Journal of Powder Materials
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• v.25 no.5
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• pp.390-394
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• 2018

Metallic tantalum powder is manufactured by reducing tantalum oxide ($Ta_2O_5$) with magnesium gas at 1,073-1,223 K in a reactor under argon gas. The high thermodynamic stability of magnesium oxide makes the reduction reaction from tantalum oxide into tantalum powder possible. The microstructure after the reduction reaction has the form of a mixture of tantalum and magnesium oxide, and the latter could be entirely eliminated by dissolving in weak hydrochloric acid. The powder size in SEM microstructure for the tantalum powder increases after acid leaching in the range of 50-300 nm, and its internal crystallite sizes are observed to be 11.5 to 24.7 nm with increasing reduction temperatures. Moreover, the optimized reduction temperature is found to be 1,173 K as the minimum oxygen concentration is approximately 1.3 wt.%.

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.73-81
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• 2001

The purpose of this study was to determine the adverse effects of methylmercuric chloride(MMC) against the fetal growth and the ossification rate of fetal pectoral and pelvic girdle, stermebrae, ribs and tail in pregnant Fischer 344 rats administered orally on day 7 of gestation. The resulted obtained are as follows. The weight and size of fetus were highly reduced by MMC. The reduction of fetal weight and size were 16. 2%~24.5%(p<0.01), and 34.1%~48.8%(p<0.01), and that of the litter’s weight were 67.0%(p<0.01) and 89.2%(p<0.01) by 20 and 30mg/kg MMC, respectively. Ossification centers were never formed in pectoral and pelvic phalanges and sternebrae, and was reduced as much as 70% in tail by 30mg/kg MMC. And also those were 82.4%~ 91.2%(p<0.01) in ischium, and 52.4~66.7%(p<0.01) in the others(ilium, fenur, tibia, fibula, metatarsals)of pelvic girdle by 30 mg/kg MMC. Ossification of sternebrae was terrible. 5th bone of sternebrae was not ossificated by 20 and 30 mg/kg MMC(p<0.01), and 2nd was also not ossificated by 30 mg/kg MMC(p<0.01).And reduction of ossification rate was 84.8~97.8%(p<0.01) in the others of sternebrae by 30 mg/kg MMC. And then, the reduction of ossification rate was 26.65~49.8%(p<0.01) in fetal ribs by 30 mg/kg MMC, and they were trend to increased as following from center to each edge. In conclusion, it was observed that fetal weight, size, and ossification of each bone were highly significantly reduced by the increased dosage of MMC.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.1
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• pp.42-47
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• 2020

In OFDM-based very high-speed communication systems, FFT/IFFT processor should have several properties of low-area and low-power consumption as well as high throughput and low processing latency. Thus, radix-2k MDF (multipath delay feedback) architectures by adopting pipeline and parallel processing are suitable. In MDF architecture, the feedback memory which increases in proportion to the input signal word-length has a large area and power consumption. This paper presents a feedback memory size reduction method of radix-22 MDF IFFT processor for OFDM applications. The proposed method focuses on reducing the feedback memory size in the first two stages of MDF architectures since the first two stages occupy about 75% of the total feedback memory. In OFDM transmissions, IFFT input signals are composed of modulated data and pilot, null signals. In order to reduce the IFFT input word-length, the integer mapping which generates mapped data composed of two signed integer corresponding to modulated data and pilot/null signals is proposed. By simulation, it is shown that the proposed method has achieved a feedback memory reduction up to 39% compared to conventional approach.