• Title, Summary, Keyword: 최적 CW

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Optimal CW Synchronization Scheme in IEEE 802.11 WLANs (IEEE 802.11 WLAN 환경에서 최적의 CW 공유 방안)

  • Lee, Jin-Lee;Lee, Su-Bin;Kyung, Yeunwoong
    • Journal of The Korea Internet of Things Society
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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.

Isolation and Characteristics of Denitrifying Pseudomonas CW4 (탈질균 Pseudomonas CW4의 분리 및 특성)

  • Hwang, Seon-Hyeon;Lee, Yeong-Ho;Jo, Mu-Hwan
    • 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.

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Isolation and Characterization of Phosphorus Accumulating Acinetobacter CW3 (인 축적균 Acinetobacter CW3의 분리 및 특성)

  • 심성훈;류원률;이영호;김정목;조무환
    • 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.

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Extraction of protein from defatted sesame meal using the enzyme from Bacillus sp. CW-1121 (Bacillus sp. CW-1121이 생성하는 단백 분해 효소를 이용한 참깨박 단백질의 용출)

  • Choi, C.;Chun, S.S.;Cho, Y.J.
    • Applied Biological Chemistry
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    • v.36 no.2
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    • pp.121-126
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    • 1993
  • To extract insoluble proteins of sesame meal residue by using microorganism, the sesame meal residue was treated with crude enzyme solution from Bacillus sp. CW-1121. It was found that the solubility reached to maximum at pH 7.5, $45^{\circ}C$. Under optimum condition, the nitrogen solubility with the enzyme solution from Bacillus sp. CW-1121 reached to 60% in 2 hours. Nitrogen solubility of protein from sesame meal showed minimum value at pH 4.5 and significantly increased above pH 6.0. When the protein from sesame meal extracted with Bacillus sp. CW-1121 was subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis, water soluble protein was showed 4 bands and salt soluble protein was showed 2 bands. The amino acid composition of water soluble protein, salt soluble protein and free amino acid indicated relatively high contents of serine (17.24 mg/g), glutamic acid (10.77 mg/g) and glutamic acid (6.55 mg/g). Specially, the contents of essential amino acids were high.

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Isolation and Characterization of Paralytic Shellfish Poison Detoxification Bacteria (마비성패류독의 생물학적 제독 -1. 마비성패류독 분해세균의 분리 및 세균학적 특성-)

  • PARK Mi Jung;LEE Hee Jung;LEE Tae Seek;PARK Jeong Heum;JANG Dong Suck
    • 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.

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A Study on the Reduction of Common Words to Classify Causes of Marine Accidents (해양사고 원인을 분류하기 위한 공통단어의 축소에 관한 연구)

  • Yim, Jeong-Bin
    • Journal of Navigation and Port Research
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    • v.41 no.3
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    • pp.109-118
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    • 2017
  • The key word (KW) is a set of words to clearly express the important causations of marine accidents; they are determined by a judge in a Korean maritime safety tribunal. The selection of KW currently has two main issues: one is maintaining consistency due to the different subjective opinion of each judge, and the second is the large number of KW currently in use. To overcome the issues, the systematic framework used to construct KW's needs to be optimized with a minimal number of KW's being derived from a set of Common Words (CW). The purpose of this study is to identify a set of CW to develop the systematic KW construction frame. To fulfill the purpose, the word reduction method to find minimum number of CW is proposed using P areto distribution function and Pareto index. A total of 2,642 KW were compiled and 56 baseline CW were identified in the data sets. These CW, along with their frequency of use across all KW, are reported. Through the word reduction experiments, an average reduction rate of 58.5% was obtained. The estimated CW according to the reduction rates was verified using the Pareto chart. Through this analysis, the development of a systematic KW construction frame is expected to be possible.

Study of Optimum Parameters for Improving QoS in Wireless LAN (무선랜 QoS의 성능향상을 위한 최적 파라미터에 관한 연구)

  • Jin, Hyunjoon
    • Journal of IKEEE
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    • v.17 no.2
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    • pp.96-103
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    • 2013
  • Since multimedia data takes large part of realtime transmission in wireless communication environments such as IEEE 802.11, QoS issues became one of the important problems with network performance. 802.11e MAC provides differentiated services based on priority schemes to solve existing 802.11 MAC problems. The TXOP is an important factor with the priority to improve network performance and QoS because it defines the time duration in which multiple frames can be transferred at one time for each station. In this paper, therefore frame sizes, TXOP Limit, and Priority values in accordance with the number of stations are experimented and derived for best network performance and QoS. Using 802.11e standard parameters, simulation results show the best throughput when the number of stations is 5 and TXOP Limit value is 6.016ms. For fairness, the best result is achieved at 3.008ms of TXOP Limit value and 15-31 of CW(Contention Window) that is lower priority than CW 7-15.

Influence of Process Parameters on Characteristics of the Cut Surface for the Case of Cutting of CSP IN Sheet Using High Power CW Nd:YAG Laser (고출력 CW Nd:YAG 레이저를 이용한 CSP 1N 박판재 절단시 공정변수의 절단표면특성에 미치는 영향)

  • 안동규;김민수;이상훈;유영태;박형준
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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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.

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Delay-Optimized Adaptive Multichannel Backoff Mechanism for VANET (VANET을 위한 지연 최적화 적응적 멀티 채널 백오프 메카니즘)

  • Lee, Jung-Jae
    • The Journal of the Korea institute of electronic communication sciences
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    • v.14 no.5
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    • pp.837-844
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    • 2019
  • In this paper, we propose the AMBM(: Adaptive Multi-channel Backoff Machisum) -Mac protocol to provide high throughput for non-safety applications in VANET(: Vehicular Ad Hoc Networks) environment. The proposed protocol guarantees the quality of service of non-safety packets by dynamically adjusting CW(: Channel Window) of WSA(: WAVE Service Advertisement) to maximize throughput between non-safety packets of different priority. It also shows that allocating a large amount of time for channel coordination and time slot reservation for SC and dynamically adjusting CW and CCI as nodes increase to reduces transmission delay than IEEE 1609.9, C-MAC(: Coordinated multi-channel MAC, and Q-VCI(: QoS Variable CCH Interval) protocols.

Change of Paralytic Shellfish Poison Components during Bacterial Detoxification (마비성패류독의 생물학적 제독 -2. 해수에서 분리한 Enterobacter sp. CW-6를 이용한 마비성패류독의 분해-)

  • PARK Mi Jung;LEE Hee Jung;LEE Tae Seek;KIM Ji Hoe;LEE Tae Ho
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.33 no.6
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    • pp.550-553
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    • 2000
  • Optimum temperature for paralytic shellfish poison (PSP) detoxofication of Enterobacter sp. CW-6 isolated from sea water and changes of contents and ingredients composition of PSP during bacterial detoxification process were investigated. Enterobacter sp. CW-6 detoxicated $61.5{\~}67.7{\%}\;and\;87.4{\~}96.8{\%}$ of initial PSP toxicity ($25.0{\~}28.5\;nmole/g$) after $5{\~}12$ days at 30 and $35^{\circ}C$, identified as optimal growth temperature, respectively. The detoxification rate of Enterobacter sp. CW-6 for crude PSP with initial concentration of 38.2 nmole/g after 8 and 12 days at $30^{\circ}C$ in the Marine broth was 88.4 and $92.7{\%}$, respectively. During bacterial detoxification process using crude toxin solution, temporary increasement of STX group was detected and identified that was derived from GTX2, 3 group. The detoxification rate of Enterobaoter sp. CW-6 on purified GTX1 and 4 with initial concentration 47 nmole/g and 37 nmole/g were more than $90{\%}$ after 12 days in the marine broth at $30^{\circ}C$. Enterobacter sp. CW-6 also showed a detoxification activity on purified GTX2 and 3, and the detoxification rate for the initial concentration 25.6 nmole/g after 12 days was $66.4{\%}$.

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