• Journal of Microbiology
• /
• v.33 no.2
• /
• pp.142-145
• /
• 1995

The pumb gene encoding a basic amino acid transport protein in Neurospora crassa could be cloned by using a mutant strain defective in pmb gene as a host strain, using a negative selection on the media containing amino acid analogue canavanine. To select positive transformants of the genes for cloning, an auxotrophic marker (his-2) was added to a pmb mutant strain by mating ; a triple mutant (pmn : pmb : his-2) was constructued by crossing a strain defective in basic amino acid transport system (# 1683-bat um 535 "A") to a double mutant strain defective in neutral amino acid transport and histidine production (mitrol : his-2 "a"). Crossing was performed on synthetic crossing (SC) media containing histidine. The pmn : pmb and pmn :pmb : his-2 strains were selected among the progeny colonies from crosses on plates containing 5- .mu.g/ml para-fluoro-phenylalanine (PFPA), 200 .mu.g/ml canavanine, and 500 .mu.g/ml histidine. The selected colonies were cultured on minimal media with or without histidine for discarding pmn : pmb strain, because the pmn : pmb : his -2 strain grows only on histidine containing media. The pmn :pmb : his-2 strain selected can be used as a host strain for the cloning of the pmb and the pmn genes from a Neurospora genomic library by means of positive selections.

• Korean Journal of Environmental Agriculture
• /
• v.32 no.3
• /
• pp.240-243
• /
• 2013

BACKGROUND: Several yeast species have potential applications in biotechnology and the identification of such yeast species is of great interest. The first step in the identification of yeasts is the establishment of an effective isolation method. Thus, we compared the efficacy of different yeast media in the isolation of yeast associated with Aloe vera and Aloe saponaria. METHODS AND RESULTS: In this study, we spread homogenized A. vera and A. saponaria leaves onto 4 different yeast selective media containing chloramphenicol, streptomycin, Triton X-100 and L-sorbose. We observed high selectivity for yeast and many colonies on media. We isolated 67 yeast strains from A. vera and 42 yeast strains from A. saponaria. We used phylogenetic analysis to identify the yeast isolates based on ITS region sequencing and performed sequence analysis on representative isolates from each agar plate. Further, we compared the sequences obtained with reference sequences. The yeast species isolated from A. vera were as follows: 56 isolates of Meyerozyma, 9 isolates of Cryptococcus, and 1 isolate each of Rhodotorula and Sporobolomyces. Those isolated from A. saponaria were as follows: 41 isolates of Rhodosporidium and 1 isolate of Sporobolomyces. CONCLUSION(S): All the isolates obtained using large agar plate containing chloramphenicol, streptomycin, Triton X-100 and L-sorbose were identified as yeast. Therefore, we concluded that this method is useful for selective screening of yeast species.

• Food Science of Animal Resources
• /
• v.30 no.2
• /
• pp.179-184
• /
• 2010

Escherichia coli O157:H7 is a food-borne pathogen that causes bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS). We compared three selective media and evaluated the performance of immunomagnetic separation (IMS) for the detection of low levels of E. coli O157:H7 in ground beef and radish sprouts with different levels of background flora. Bulk food samples (500 g for each trial) were artificially inoculated with nalidixic acid-resistant E. coli O157:H7 at the lowest dose that would generate 20 partial-positive samples of 25 g each. All samples were homogenized in mTSB (225 mL) and incubated overnight at $37^{\circ}C$. IMS was performed using the enriched mTSB samples (1 mL) along with conventional spreads plated onto three different selective media: Sorbitol MacConkey agar (SMAC), Sorbitol MacConkey agar with cefixime and tellulite (CT-SMAC), and Sorbitol MacConkey agar with nalidixic acid (NAL-SMAC) as the gold standard. Two suspicious colonies from each medium were selected and confirmed usinga serological test after transfer to tryptic soy broth with yeast extract (TSAYE). CT-SMAC was better than SMAC for detecting E. coli O157:H7 in all food types. Although there was no statistical difference in the number of positive samples when using IMS vs. non-IMS techniques, more positive samples were detected when IMS was used in both ground beef and radish sprouts. It appears that the improvement was more significant in radish sprouts, which had a higher level of background flora than ground beef. The results also suggest that the combination of CT-SMAC and IMS is sufficient to recover low levels of E. coli O157:H7 in high background flora food samples.

• Journal of Broadcast Engineering
• /
• v.16 no.1
• /
• pp.123-132
• /
• 2011

Recently, DVC (Distributed Video Coding) is receiving a lot of attention as one of the low complexity video encoding techniques suitable for various applications with computation-limited and/or power-limited environment, and is being actively studied for improving the coding efficiency. This paper proposes a rate-distortion based selective block encoding scheme. First, the motion information is obtained in the process of generating side information at decoder and received through the feedback channel, and then, based on this information, the proposed method performs a selective block encoding based on rate-distortion optimization. Experimental results show that the performance of the proposed scheme reaches up to 2.2 dB PSNR gain over the existing scheme. Moreover, it is shown that the complexity can be reduced by encoding parts of region considering rate-distortion cost.

• Journal of Broadcast Engineering
• /
• v.25 no.6
• /
• pp.1013-1016
• /
• 2020

This paper presents a selective encryption and decryption method exploiting the start code of the IVC bitstream. The existing encryption methods for video are largely classified into two methods: Naive Encryption Algorithm (NEA) and Selective Encryption Algorithm (SEA). Since NEA encrypts the entire bitstream, it has the advantage of high security but has the disadvantage of high computational complexity. SEA improves the encryption and decryption speed compared to NEA by encrypting a part of the bitstream, but there is a problem that security is relatively low. The proposed method improves the encryption and decryption speed and the security of the existing SEA by using the start code of the IVC bitstream. As a result of the experiment, the proposed method reduces the encryption speed by 96% and the decryption speed by 98% on average compared to the NEA.

• The Journal of the Korea Contents Association
• /
• v.21 no.5
• /
• pp.157-169
• /
• 2021

YouTube has rapidly grown as a news media outlet. As political content without fact-checking is actively provided and YouTube algorithms are used for content recommendations, users are selectively exposed to certain political ideologies, which could escalate conflicts among political groups. In particular, the stronger the identification of in-group, the greater the antipathy toward outgroup, and the more exposed the content to the parties that support or oppose it, the stronger the identification or the antipathy can be. This study investigated the relationship between selective exposure and political attitude polarization in the context of political video on YouTube. Based on social identity theory, this study also found that political identification mediates the relationship between selective exposure and political attitude polarization.

• International Journal of Internet, Broadcasting and Communication
• /
• v.15 no.4
• /
• pp.31-43
• /
• 2023

News credibility is on a decline for many democratic countries. Among the countries, South Korea is currently witnessing one of the steepest declining curves. Since people obtain news from various media, for example, television and portals, news credibility can be measured for each of the media separately. Most often, television news credibility is much higher than portal news credibility because people tend to trust traditional media more than online ones. To understand the discrepancy between news credibility of the two media in specific relation to South Koreans' everyday news use and overall news credibility evaluation, this exploratory study examined how the factors that influence television news credibility and portal news credibility differ from each other by examining the relations of news credibility of the two media to credibility of news I use and of news in general. Drawing from previous research on partisan news use, it assumed that normative beliefs for television as a traditional medium work for television news credibility in the similar way as the mechanisms of selective exposure and bias perception do. It also assumed that the experiences dimension of news trust works for credibility of portal news and of news in general similarly. To verify these assumptions, a regression analysis was conducted from a sample of 58,936 South Koreans collected in 2022. As assumed, results revealed a greater relation between credibility of television news and of news I use, and between credibility of portal news and of news in general respectively. The findings suggest that measurement of credibility should be revised in the way that reflects media characteristics and the differing expectations held by news users.

• Proceedings of the IEEK Conference
• /
• 2003.11a
• /
• pp.485-488
• /
• 2003

A conventional correlation target tracker is analysed with a simple mathematical approach. And, we will propose a correlation measure with selective attentional property in order to overcome the false-peak problem of the conventional methods. Various experimental results show that the proposed correlation measure is able to reduce considerably the probability of false-peaks degraded by the correlation between background images of a reference block and a distorted and noisy sensor input image.

• Korean Journal Plant Pathology
• /
• v.12 no.2
• /
• pp.197-201
• /
• 1996

우리나라 포도재배 지역인 포천, 남양주 및 수원의 포도나무 줄기혹병에 이병된 포장으로부터 채집한 줄기혹(gall), 수액(sap) 및 근권토양으로부터 56균주의 유사 Agrobacterium를 분리하였으며, 이들 중 7균주가 포도나무 유묘의 줄기에 혹ㅇ르 형성시키는 병원성 Agrobacterium biovar의 선택배지에서의 생장, oxidase의 생성, Na L-tartrate로부터 알칼리의 성장, 2% NaCl 첨가 배지에서 생장, 3-ketolactose의 비생산, mesoerythritol과 ethanol로부터 산을 생성하지 못하는 등 Agrobacterium biovar 3인 A. vitis로 동정되었다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2004.05a
• /
• pp.1355-1358
• /
• 2004

This paper describes a modification to the SACK (Selective Acknowledgement) Transmission Control Protocol's (TCP), called SACK TCP with Probing Device, SACK works in conjunction with Probing Device, for improving SACK TCP performance when more than half a window of data lost that is typical in handoff as well as unreliable media. It shows that by slightly modifying the congestion control mechanism of the SACK TCP, it can be made to better performance to multiple packets lost from one window of data.