• Journal of Internet of Things and Convergence
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• v.6 no.4
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• pp.15-19
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• 2020

In this paper, we propose a optimal CW(Conention Window) synchronization scheme in IEEE 802.11 WLANs. IEEE 802.11 WLANs support DCF(Distributed Coordination Function) mode for the MAC(Medium Access Control) operation. In DCF, the CW increases exponentially according to the collisions and becomes minimum CW according to the success of data transmissions. However, since the base minimum CW value is hardware or standard specific, the number of active stations and network status are not considered to determine the CW value. Even though the researches on optimal CW have beend conducted, they do not consider the optimal CW synchronization among mobile stations which occur network performance degradation. Therefore, this paper calculates the optimal CW value and shares it with mobile stations in the network.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.158-159
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• 2003

In four-wave-mixing wavelength converter, we investigated the performance through simulation by using VPI tool, changing the input signal power and CW power at 2.SGb／s. Controlling optimal CW power to each input signal power, we extended the input signal power range to 20dB, which guarantees the minimum power penalty.

• KSBB Journal
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• v.14 no.1
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• pp.71-75
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• 1999

A highly effective phosphorus accumulating bacterium named Acinetobacter CW3 was isolated from the nature by using Winogradsky columns. The optimal cultivation conditions of Acinetobacter CW3 in shaking flask were determined as $20^{\circ}C$, pH 7, 200rpm, 18.5mg $PO_4$-P/L. Acientobacter CW3 could remove phosphorus completely in 12hours for a batch culture at optimal cultivation condition. This bacterium could uptake phosphorus on aerobic condition and release it on anaerobic condition.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.6
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• pp.546-549
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• 2000

For the establishment of biodetoxification method which can be acceptable for live bivalves, paralytic shellfish poison (PSP) detoxification bacteria were isolated from sea water and bivalves, and PSP detoxification activity and optimal growth condition of the isolated strains were investigated. from the bivalve and sea water samples, 8 strains of PSP detoxification bacteria were isolated. Of the isolated strains, CW-6 isolated from sea water shown strong PSP detoxification activity and decomposed completely 18 nmole/g of GTX2 after 3 days incubation in artificial medium. The selected stain CW-6 shown typical characteristics of the Enterobacter sp. and identified as Enterobacter sp, CW-6. Optimal growth condition of the Enterobacter sp. CW-6 were $35^{\circ}C$, pH 7 and $NaCl 1{\%}$, respectively.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.286-291
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• 2004

The objective of this research work is to investigate the influence of process parameters, such as power of laser, travel speed of laser and material thickness, on roughness and striation of the cut surface for the case of cutting of CSP 1N sheet using high power Nd:YAG laser with continuous wave(CW). In order to find the practical cutting region and the relationship between process parameters on the roughness and the striation, several laser cutting experiments are carried out. From the results of experiments, the allowable cutting region and an optimal cutting speed for each cutting condition have been obtained to improve the quality of the cut surface. In addition, it has been shown that the surface roughness is related to the number of striation and depth of valley of the cut surface.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.162-165
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• 2005

The objective of this research work is to investigate into the three-dimensional temperature distribution using quasi steady-state heat transfer analysis fur the case of the laser cutting of CSP 1N sheet using high power CW Nd:YAG laser. The laser heat source is assumed as a volumetric heat source with a gaussian heat distribution in a plane. Through the comparison of the results of analyses with those of the experiments, the optimal finite element model is obtained. Finally, characteristics of the three-dimensional heat transfer and temperature distribution have been estimated by the optimal finite element model.

• KSBB Journal
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• v.14 no.5
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• pp.616-620
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• 1999

Ten denitrifying bacteria, which were identified as Pseudomonas sp., were isolated from Winogradsky columns. The most effective denitrifying bacterium was named as Pseudomonas CW4, which was cultivated at anoxic condition. The optimal growth temperature and pH were 3$0^{\circ}C$ and 6-8, respectively. The effect of carbon concentration and agitator speed on the rate of denitrification were very low. 100% of NO$_3$-N was removed after 15 hrs when initial concentration of NO$_3$-N was 142.5 mg/L.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.5
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• pp.35-43
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• 2007

Laser welding of metals has been widely used to improve a wear resistance and a corrosion resistance of the industrial parts. The objective of this research works is to investigate the influence of the process parameters, such as the welding for metals with CW Nd:YAG lasers. The bead-on-plate welding tests are carried out for several combinations of the experimental conditions. In order to quantitatively examine the characteristics of the butt welding, the welding quality of the cut section, stain-stress behavior and the hardness of the welded part are investigated. From the results of the investigation, it has been shown that the optimal welding condition without defects in the vicinity of the welded area and with a good welding quality is 1325W of the laser power, and 1.4m/min of laser welding speed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.11
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• pp.886-897
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• 1990

This paper is proposed new optimal PWM scheme is based on a defined linear relationship between the successive pulsewidths of the PWM pattern. The calculation of the pulsewidths in the new PWM scheme is caried out without referring to the equations of CW and MW. With this scheme the PWM pattern for microprocessor controlled inverters can be composed easily by obtaining the optimal increment in sucessive pulsiwidths of the pattern. Furthmore, the harmonic level at the output of PWM inverter are always very low because this PWM pattern is selected on the basis of minimum THD. Theis scheme is applied to 1(Hp), three phase induction motor, and compared with conventional regular PWM scheme. The results of calculations and experiments show that new optimal PWM scheme could provide an effective generalized approach for minimization of harmonics in the VSI-PWM inverter.

• Journal of the Korean Wood Science and Technology
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• v.43 no.3
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• pp.390-399
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• 2015

This study was conducted to examine the potential use of coffee waste (CW) as an adsorbent of HCHO by adding into fiberboard. For the purpose, CW treated with various temperatures and times was placed in desiccator with a HCHO solution and then the HCHO adsorptivity of the CW was measured by acetylacetone (ATAN) and DNPH methods. In the results of ATAN analysis, amount of HCHO adsorbed in distilled water was the lowest on the non-treated CW and steadily increased to $100^{\circ}C$-treated temperature. However, over the $100^{\circ}C$, heating temperature (H-Temp) had not an effect on the HCHO adsorptivity of CW. Amount of HCHO adsorbed on CW itself was the highest at $100^{\circ}C$ H-Temp, following by $50^{\circ}C$, $150^{\circ}C$, $0^{\circ}C$, $250^{\circ}C$ and $200^{\circ}C$. For the HCHO adsorptivity of CW measured by DNPH methods, HCHO was not detected in the distilled water stirred with non-treated CW, but detected from the distilled water stirred with heating-treated CW. The content was the highest in the CW heating-treated at $100^{\circ}C$ for 10 min. In addition, HCHO adsorbed on CW itself increased to the H-Temp of $100^{\circ}C$ regardless of heating time, but decreased or reduced greatly degree of the increase over $100^{\circ}C$ H-Temp. In conclusion, optimal heating conditions of CW for the HCHO adsorption might be H-Temp between 100 and $150^{\circ}C$ with 10 min according as technical and economical reasons. Heating-treated CW manufactured with above the conditions can be used as an adsorbent in conventional fiberboard production for reducing HCHO emssion.