• 사물인터넷융복합논문지
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• 제6권4호
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• pp.15-19
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• 2020

본 논문은 IEEE 802.11 WLAN 환경에서 최적의 CW(Contention Window) 값을 구하고 해당 값을 네트워크 내의 모든 단말들 및 새롭게 접속할 단말들과 공유하는 방법을 제안하고자 한다. IEEE 802.11 WLAN의 기본 MAC(Medium Access Control) 방식은 DCF(Distributed Coordination Function)를 지원하는데, DCF는 단말의 데이터 전송 성공 여부에 따라 실패 시 CW를 2배로 증가시키고, 성공 시 CW를 초기값으로 초기화시키는 동작을 반복한다. 하지만 이러한 기존의 DCF CW 조정 방식은 하드웨어 칩셋 또는 표준에 정의되어 있는 고정된 CW 초기값을 이용해서 동작하기 때문에 네트워크 상황 및 단말의 수에 따른 동적인 변경을 고려하지 않았다. 이를 해결하기 위해 최적의 CW 값을 구하는 연구들이 진행되었지만 기존 연구들은 최적의 CW 값에 대한 단말들의 동기화 과정을 고려하지 못하였고 이는 성능 저하를 발생시킬 수 있다. 그러므로 본 연구에서는 네트워크 상황 및 단말의 수를 고려하여 최적의 CW 값을 구하고, 해당 값을 단말들과 동기화 시키는 방안을 제시하고자 한다.

• Asian-Australasian Journal of Animal Sciences
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• 제21권4호
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• pp.532-537
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• 2008

In order to investigate the factors affecting the culture of mouse preantral follicles in vitro, we examined the effect of culture media, protein supplements, and culture period on their growth. The oocyte diameter (initial size: $55.6{\pm}2.5{\mu}m$) was progressively increased during culture, and the maximum size ($72.0{\pm}2.4{\mu}m$) was reached on day 10 of the in vitro culture. The chromatin configuration in the germinal vesicle (GV) oocyte progressively shifted from a non-surrounded nucleolus (NSN) to a surrounded nucleolus (SN). On day 10 of the culture, most of the oocytes progressed to the SN pattern. The survival and metaphase II rates of the oocytes in alpha-minimal essential medium (alpha-MEM) were significantly higher (p<0.05) than those in Waymouth and tissue culture medium (TCM)-199. As a protein source, fetal bovine serum (FBS) was more suitable for the culture of mouse preantral follicles as compared to human follicular fluid (hFF) and bovine serum albumin (BSA); the optimal concentration of FBS was 5%. These results suggest that in a culture of mouse preantral follicles, alpha-MEM and 5% FBS are an optimal medium and a protein source, respectively; further, the 10 days of culture is required for the complete growth of oocytes in this culture system.

• Food Science and Biotechnology
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• 제17권5호
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• pp.904-911
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• 2008

Covalent cross-links between a number of proteins and peptides explain why transglutaminase may be widely used by food processing industries. The objective of this work was optimization of the fermentation process to produce transglutaminase from a new microbial source, the Streptomyces sp. P20. The strategy adopted to modify the usual literature media was: (1) fractional factorial design (FFD) to elucidate the key medium ingredients, (2) central composite design (CCD) to optimise the concentration of the key components. Optimization of the medium resulted in not only an 86% increase in microbial transglutaminase activity as compared to the media cited in the literature, but also a reduction in the production cost. Optimal fermentation conditions - namely temperature and agitation rate - were also studied, using CCD methodology. Usual conditions of $30^{\circ}C$ and 100 rpm were within the optimal area. All other parameters for enzyme production were experimentally proven to be optimum fermentation conditions.

• 한국미생물·생명공학회지
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• 제25권3호
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• pp.298-304
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• 1997

Thermus caldophilus GK24 was selected as sources of thermostable $\beta$-galactosidase from a survey of genus Thermus. T. caldophilus GK24 (Tca) $\beta$-galactosidase was found to be inducible. The enzyme was optimally active at 75$\circ$C. Enzyme induction was achieved by addition of lactose, galactose and cellobiose to basal media. The addition of glucose to culture media had a repressive effect on further enzyme synthesis. T caldophilus GK24 was tested for production of $\beta$-galactosidase by addition of various concentration of lactose, galactose and cellobiose to standard media. Cellobiose was found to be effective for the $\beta$-galactosidase induction. The optimal induction medium for production of $\beta$-galactosidase was composed of 0.2% cellobiose, 0.3% bactotryptone, 0.3% yeast extract, basal salts and Tris/HCI(pH 7.8). The activity of the enzyme in the optimal induction medium increased nearly 16.5-fold compared to the standard medium. Tca $\beta$-galactosidase was detected when cell extracts was subjected to electrophoresis in a nondenaturing polyacryamide gel and stained for activity with 6-bromo-2-naphtyl-$\beta$-D-galactopyranoside(BNG).

• Journal of Plant Biotechnology
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• 제30권3호
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• pp.245-249
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• 2003

This study was carried out to establish a regeneration system from leaf explant of purple sweetpotato(Ipomoea batatas L.) The optimal concentrations of plant growth regulators for callus induction and shoot formation were determined. The optimal combination for callus formation was 1$\mu$M 2,4-D 5$\mu$M BM, and highest yield of embryogenic calli were observed on Murashige and Skoog basal medium containing 0.5$\mu$M 2,4-D under light condition after 4weeks of culture. Embryogenec callus was subcultured on medium supplemented with 5$\mu$M ABA for 4 days. Subsequently, regeneration of adventitious shoots occurred when these embryogenic calli were transferred onto medium with 3∼6$\mu$M gibberellic acid. Regenerated shoots were developed into normal plantlets.

• 한국식품영양과학회지
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• 제27권1호
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• pp.51-56
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• 1998

A bacteium, KP-6408, capable of hydrolyzing fibrin was isolated from Chungkook-jang, which was possibly identified as a strain of Bacillus sp. The effects of culture condition and medium composition on the enzyme production were investigated. Among nitrogen sources tested, yeast extract was the most effective for the enzyme production, and the level of the concentration for the optimal enzyme production was 0.2%(w/v). For carbon sources, glucose was the best for the enzyme production with the level of 2.0%(w/v). The enzyme was maximally produced by cultivating the enzyme production with the level of 2.0%(w/v). The enzyme was maximally produced by cultivating the organism at the liquid medium of the initial pH 8.0 and temperature of 4$0^{\circ}C$. In Chungkook-jang fermentation, the enzyme was maximally produced when incubated at 35$^{\circ}C$ for 24 hrs using soybean as a solid medium. The addition of various rice starch to the soybean in Chungkook-jang fermentation lowered the enzyme production.

• KSBB Journal
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• 제9권4호
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• pp.436-442
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• 1994

Aspergillus terreus NRRL 1960에 의한 이다콘산의 생산에 관해 연구하였다. pH, 접종량, 배지조성 등의 최적조건을 확립하였다. 이타콘산의 최대생산 량은 37°C, pH 2.5의 조건에셔, 5% (w/v) glu­c cose, 0.5 % (w/v) $NH_4Cl$, 0.2 % (w/v) yeast ex­tract, 0.1 % (w/v) $MgSO_4$, 0.2 % (w/v) NaCI을 포함하는 배지에서 7일만에 $19.18g/\ell$를 얻을 수 있었다. 종균배양 배지로서 2 % malt extract가 적합하였다. 교반식 반응기에서 유리균체에 의한 이타콘 산의 회분식 생산은 플라스크 배양에 비해 비효율적 이었다.

• Reproductive and Developmental Biology
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• 제29권3호
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• pp.145-147
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• 2005

Autocrine or paracrine mediators released by the early embryo are implicated in the support of embryonic development. Their mechanisms and optimal embryo density in the medium, however, are uncertain. This study was conducted to establish the optimal embryo density and culture medium volume in mouse parthenogenetic embryo culture. In experiment 1, culture of parthenogenetirally activated oocytes at a concentration of $2{\~}4$ embryos/${\mu}L$ significantly improved development to the blastoryst stage ($72{\%}{\leq}$) compared with culture at the lower ($0.2{\~}1$e mbryos/${\mu}L,\;0\~37.5\%$) and the higher ($5{\~}6$ embryos/${\mu}L,\;30\~53\%$) concentration for 120 h when the oocytes were cultured in a 5 ${\mu}L$ drop under mineral oil In experiment 2, the embryos cultured at a concentration of $2{\~}4$ embryos/${\mu}L$ in a 10 ${\mu}L$ drop ($81.1{\%}$) showed significantly higher blastocyst rates than those in a 5 ${\mu}L$ drop ($68.5{\%}$). This study optimizes in vitro culture condition by modifying embryo density and the volume of culture medium It may give appropriate level of autocrine and/or paracrine factors to enhance viability and subsequent normal development of mouse parthenogenetic embryos in vitro.

• Journal of Plant Biotechnology
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• 제7권1호
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• pp.57-65
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• 2005

The $F_1$ hybrid Red Coat is one of the most highly sought after cultivars of tomato in Australia and yields up to 7.5 $\cal{kg/plant}$. An experiment was conducted to de-termine the optimal strength and type of growth medium and sucrose concentration for shoot organogenesis of the Red Coat cultivar using cotyledonary explants. Two basal growth media, viz. MS and Gamborg' s $B_5$ at 0, 1/4, 1/2, full or double strength along with sucrose concentrations of 0, 0.5, 1.5, 3 or $5\%$, were evaluated using 25 replications. The main effects of treatment and their mutual interactions were evaluated for the proportion of explants that produced callus and/or shoots, number of shoots produced per explant, callus diameter and shoot height. The explants failed to produce shoots in the absence of mineral nutrient. Only a small proportion of the explants ($6\%$ with $B_5\;and\;3\%$ with MS) regenerated shoots in the absence of sucrose. Lower sucrose concentrations ($0.5-1.5\%$) along with full strength media were optimal for most of the traits studied. The $B_5$ medium outperformed MS medium for shoot organogenesis. For all the traits examined, significant differences in main effects (P < 0.05) and two-way interactions were detected, but no three-way interactions (medium type $\times$ medium concentration $\times$ sucrose concentration) were observed. Sucrose was found essential for the development of chlorophyll. Chlorophyll content increased with an increase in sucrose concentration up to $3\%$ and decreased at $5\%$ sucrose.

• The Korean Journal of Ecology
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• 제25권6호
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• pp.389-393
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• 2002

Effects of environmental factors on in vitro pine pollen performance were investigated. Pinus densiflora and P. rigida pollen grains collected at Mt. Kwanak, Korea were used. Three environmental factors, such as pollen storage temperature, pollen culture temperature and nutrient condition in medium, were tested. To determine the storage temperature effects on pollen viability, pine pollen was stored at $-70^{\circ}C$, $-12^{\circ}C$, $4^{\circ}C$ and $22^{\circ}C$. Pollen viability was substantially extended at the storage temperatures of $-12^{\circ}C$ and $4^{\circ}C$ for more than 300 days. To elucidate the culture temperature effects on pine pollen germination and tube growth, pollen grains were cultured at the temperatures from $5^{\circ}C$ to $40^{\circ}C$ at $5^{\circ}C$intervals. The germination rate and tube growth were highest at $25^{\circ}C$ and decreased above $30^{\circ}C$. To investigate boron and sucrose effects on pollen tube growth, the pollen was cultured at different sucrose and boric acid concentrations. Germination rate was optimal in germination medium containing 3 or 5$\%$ sucrose with 0.01 $\%$ boric acid. These results indicate that the pine pollen can be stored for considerable length of time without noticeable loss of viability at storage temperature below or near $0^{\circ}C$. Optimal germination medium conditions were established for pine pollen. Therefore, pine pollen can be used for many biological and environmental monitoring researches.