• Research in Plant Disease
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• v.26 no.4
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• pp.264-271
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• 2020

We have developed a simultaneous diagnostic method that can identify both the species of thrips and tomato spotted wilt virus (TSWV) that are problematic in chrysanthemum plants. This is a method of amplifying DNA by performing reverse transcription-polymerase chain reaction by simultaneously adding primers specific to TSWV coat protein (N) gene and primers specific to the internal transcribed spacer 2 region of Frankliniella occidentalis and F. intonsa using total nucleic acid extracted from one thrips. The sizes of DNA fragments for TSWV, F. occidentalis, and F. intonsa were 777, 287, and 367 bp, respectively. These results showed species identification of thrips and whether thrips carrying TSWV can be simultaneously confirmed. Further usefulness of the simultaneous diagnostic method was made from greenhouse survey at chrysanthemum greenhouses in Taean (Chungcheongnam-do) and Changwon (Gyeongsangnam-do) to investigate the identification of thrips species and the rate of thrips carrying TSWV. Of thrips collected from the greenhouses, 83.7% thrips was F. occidentalis and 72.9% F. occidentalis carried TSWV in Taean. Similarly, the diagnostic method showed that 92.2% thrips was F. occidentalis and 84.0% F. occidentalis carried TSWV in Changwon. These results confirm that F. occidentalis is a dominant thrips species and the thrips species plays a crucial role in the transmission of TSWV in chrysanthemum plants in the greenhouses. Taken together, this study showed a simple diagnostic method for thrips identification and epidemiological studies of the timing and spread of TSWV through thrips in chrysanthemum greenhouses in South Korea.

• Korean Journal of Environment and Ecology
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• v.36 no.6
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• pp.639-650
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• 2022

Abeliophyllum distichum Nakai, a rare plant with distylous characteristics, is native to certain parts of the Korean Peninsula. It is registered on the IUCN Red List of Threatened Species as a globally endangered plant. This study was conducted to establish an appropriate local conservation management plan suitable for future A. distichum populations by comparing and analyzing the flowering characteristics and population size according to distyly based on the results of quantitative surveys in 14 regions, including 8 areas with native populations of A. distichum and 6 natural monument populations. The number of individuals appearing in each population group was surveyed, and the flowering individuals were identified by style as being either pin or thrum flower types as they were being examined and recorded on the site. In total, 13,130 individuals of A. distichum (7,003 flowering and 6,127 non-flowering individuals) were recorded, but the balance of the number of pin- and thrum-flowered individuals in each population was not significant (p<0.05), indicating an imbalanced state. In particular, the Yeongdong (YD) population was very disproportionate compared to other populations, suggesting that its genetic diversity was low and the possibility of inbreeding was high. The average flowering and fruiting rates by management unit were much higher in the natural monument populations (89.2% and 55.3%, respectively) than in the natural habitat populations (39.0% and 8.5%, respectively). It may be due to a difference in reproductive growth resulting from light inflow into the forest caused by the upper crown closure. The area of occupation (AOO) of A. distichum on the Korean Peninsula covered an area of 23,224.5 m². Although the natural monument population was smaller than the natural habitat population, its density was higher, likely as a result of the periodic management of natural monument populations, where the installation of protective facilities in certain areas restricts population spread. Conservation of A. distichum populations requires removing the natural monument populations suspected of anthropogenic and genetic disturbances and expanding the conservation priority population by designating new protected areas. Although the habitats of natural monument populations are managed by the Cultural Heritage Administration and local governments, there are no agencies that are responsible for managing natural habitat populations. Therefore, institutional improvement in the overall management of A. distichum should be prioritized.

• Journal of Food Hygiene and Safety
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• v.39 no.1
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• pp.16-25
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• 2024

This study investigated the prevalence of Campylobacter spp. In poultry meat and its association with foodborne illnesses in Gwangju, South Korea. It was found that out of the 307 samples of poultry meat examined, 111 (36.2%) were infected with Campylobacter spp. Among the isolated strains, 102 were identified as Campylobacter jejuni and 14 as Campylobacter coli. The detection rate of Campylobacter spp. was higher in duck meat (63.1%) than in chicken meat (26.0%). In 5 samples (1 chicken, 4 duck), both Campylobacter jejuni and Campylobacter coli were found together. The antimicrobial resistance test showed that 99 strains were resistant to more than one antimicrobial. The most common antimicrobial resistance was seen against ciprofloxacin (84.5%), followed by nalidixic acid (82.8%), tetracycline (44.0%), and gentamicin (2.6%). The isolated Campylobacter spp. were serotyped and the results showed the presence of HS2 (20 strains), HS15 (11 strains), HS19 (9 strains), and HS8 (8 strains). Considering the findings, it is recommended to maintain hygienic practices during the cooking process and to take necessary precautions to prevent the spread of pathogenic bacteria.

• Korean Journal of Environment and Ecology
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• v.38 no.3
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• pp.246-262
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• 2024

The survey conducted from 2018 to 2020 aimed to investigate the changes in fish fauna and community characteristics in the upper reaches of the Seomgang River, Korea. During the survey period, 35 sites were selected, resulting in the collection of 7,817 fish belonging to 12 families and 40 species. The dominant species was Zacco koreanus, with a relative abundance of 34.5%, followed by Z. platypus at 28.7%. Other significant species included Rhynchocypris oxycephalus (10.2%), Pungtungia herzi (5.3%), and Squalidus gracilis majimae (4.3%). Notably, four protected species - Acheilognathus signifer, Gobiobotia brevibarba, and Cottus koreanus, designated as class II endangered wildlife by the Ministry of Environment- were identified. These species predominantly inhabit the middle and lower reaches, except for Gobiobotia brevibarba, which is found in the upper reaches. Nineteen species, accounting for a 47.5% endemism rate, were endemic to Korea. The study also noted the presence of one climate-sensitive species, Cottus koreanus, and two exotic species, Carassius cuvieri and Micropterus salmoides. Community analysis indicated a trend of decreasing dominance and increasing diversity and richness from upstream to downstream, with a distinct division into uppermost reaches, upper reaches, middle and lower reaches, and lakes. The construction of the Hwaseong Dam has had a significant direct and indirect impact on the fish community. The habitat and abundance of endangered species such as R. pseudosericeus, A. signifer, and G. brevibarba decreased dramatically immediately after the dam's construction, transforming the submerged area from lotic to lentic environments. Approximately 20 years later, the habitats have stabilized, leading to an increase in the fish population and a recovery of the previously diminished endangered species. The river health (FAI) was also evaluated, with 27 sites rated as very good (A), seven as good (B), and one as fair (C). However, endangered species such as A. signifer continue to face threats from dam and river construction, while C. Koreanus has experienced a severe population decline due to river works. Additionally, the presence of the ecosystem-disrupting species M. salmoides in Hwaseong Lake raises concerns. To ensure a stable habitat for fish in the upper reaches of the Seomgang River, it is crucial to avoid indiscriminate river construction, urgently implement restoration policies for endangered species such as A. signifer, and develop management strategies to control the spread of invasive species such as bass.

• Korean Journal of Agricultural Science
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• v.4 no.2
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• pp.283-316
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• 1977

In an attempt to obtain a basic information to develop an effective integrated system of controlling sheath blight of rice in Korea, the transition of this disease, the variation of cultural characters and pathogenicity of the pathogen, environmental conditions affecting the disease outbreak and varietal resistance have been investigated. 1. Rice sheath blight which has been minor disease in the past was widely spread, especially since 1971. This disease has promptly spread all over the country and infected 65.2% of total rice growing area in 1976. Various factors are considered to be related to such transition of this disease. Above all, increace of application of nitrogenous fertilizer, early season and earlier cultivation of rice, introduction of more susceptible "Tongil" varieties etc. must be important factors influencing the outbreak of this disease. 2. Great variations in cultural characteristics-such as mycelial growth rate, color of the medium, amount of the aerial mycelium, shape and color of the sclerotia- and in the pathogenicity of isolates of the pathogen, Thanatephorus cucumeris Dank were observed. The optimum temperature for mycelial growth also varied with isolates, from $25^{\circ}C$ to $30^{\circ}C$. There were not necessarily any correlation between curtural characteristics and pathogenicity of isolates of Thanatephorus cucumens. 3. Mycelial grow th of isolates of Thanatephorus cucumens on the PDA medium were correlated with the air temperatures of the region where the isolates were collected. The isolates from the regions with high temperature grew well on PDA medium at $35^{\circ}C$ than those from the region with low temperature, on the other hand, the isolates from the regions with the low temperature grew well on the same medium at $12^{\circ}C$ than those from the regions with high temperature. 4. Pectin polygalacturonase (PG) and cellulase (Cx) were most active on the 3rd day after inoculation on the leaves of rice plant with Thanatephorus cucumeris, whereas pectin methylestrase (PE) was most active on the 4th day after inoculation. Relationship between the activities of PE of isolates and the strength of pathogenicity of isolates was obtained, but PG and cellulase activities were not correlated with pathogenicity of isolates. 5. The tolerence of sclerotia from in-vitro culture to low temperature varied with their water content, the dried cultural sclerotia were more tolerent than wet ones, Dried cultural sclerotia maintained almost 100% germinability for 45 days at $-20^{\circ}C$, whereas wet sclerotia lost viability at $-5^{\circ}C$. The germination ratio of the sclerotia after overwintering changed from 18% to 70% according to the water content of the test paddy fields and the ratio was low in wet paddy condition. 6. To investigate the host range of this fungi in and near paddy field, 17 weeds were inoculated with fungi. The lesions of sheath blight disease was obserbed on Sagittaria trifolia L., Echinochloa crusgalli P. Beauv., Monochoria vaginal is Presl, Polygonum Hydropiper L., Eclipta prostrata L., Digitaria sanguinalis Scapoli. 7. When the level of nitrogen applied was doubled over standard level, total nitrogen content in rice sheath increased, ami when silicate was applied, starch content in rice sheath decreased, inducing the rice plants more susceptible to sheath blight disease. Increased dressing of potash ferilizer reduced the incidence of sheat blight disease. 8. The percentage of infected stems in the early period increased more in the narrow hill plot than in the wide hill plot, but in the late period this tendency was inversed; the percentage of infected stems as well as severity in the wide hill plot increased more compared to the narrow hill plot, and the disease severity in the one plant per hill plot was also low. The number of stems in the wide hill plot was more than the number of stems in the narrow hill plot. This indicates that the microclimate, such as the relative humidity, in the narrow hill plot was more favorable for the development of this disease. 9. There was a high negative correlation between the disease severity of varieties to the sheath blight and the maturity of the varieties, that is, the early varieties were more susceptible than the late ones, and much-tillering varieties usually showed more infection than less tillering varieties. 10. No relationship was obtained between the percentage of infected stems in the early period and the severity after heading, whereas a distinct relationship was obtained between former and latter after Aug. 10.

• Tuberculosis and Respiratory Diseases
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• v.61 no.3
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• pp.248-255
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• 2006

Background: LOH11A is a region with frequent allele loss (>75%) in lung cancer that is located on the centromeric part of chromosome 11p15.5. Clinical and cell biological studies suggest that this region contains a gene associated with metastatic tumor spread. RRM1 encoding the M1 subunit of ribonucleotide reductase, which is an enzyme that catalyses the rate-limiting step in deoxyribonucleotide synthesis, is located in the LOH11A region. Methods: Polymorphisms were found at nucleotide position (-)37 (C/A) and (-)524 (C/T) from the beginning of exon 1 of the RRM1 gene that might regulate the expression of RRM1. We studied the polymorphisms in 127 Korean individuals (66 lung cancer and 61 normal controls) and compared with those of 140 American patients with lung cancer. Results: CC, AC and AA were found at the (-)37 position in 64(50.4%), 55(43.3%), and 8(6.3%) out of 127 Korean individuals (66 cancer, 61 non-cancer patients), respectively. There was a similar frequency of allele A at (-)37 in the American(27.9%) and Korean population(28.0%). CC, CT and TT was found at the (-)524 position in 24(18.9%), 44(34.6%), and 59(46.5%) out of the 127 Korean individuals, respectively. There was a similar frequency of allele C at (-)524 in the American(34.6%) and Korean population(36.2%). There was no difference in the frequency of the (-)37 and (-)524 genotypes between the cancer and non-cancer group. However there was a significant correlation of the genotypes between (-)37 and (-)524 (p<0.001), which suggests the possible coordination of these polymorphisms in the regulation of the promoter activity of the RRM1 gene. Conclusion: RRM1 promoter polymorphisms were not found to be significant risk factors for lung cancer. However, a further study of the promoter activity and expression of the RRM1 gene according to the pattern of the polymorphism will be needed.

• Journal of Intelligence and Information Systems
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• v.23 no.3
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• pp.69-94
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• 2017

Recently, increase of demand for big data analysis has been driving the vigorous development of related technologies and tools. In addition, development of IT and increased penetration rate of smart devices are producing a large amount of data. According to this phenomenon, data analysis technology is rapidly becoming popular. Also, attempts to acquire insights through data analysis have been continuously increasing. It means that the big data analysis will be more important in various industries for the foreseeable future. Big data analysis is generally performed by a small number of experts and delivered to each demander of analysis. However, increase of interest about big data analysis arouses activation of computer programming education and development of many programs for data analysis. Accordingly, the entry barriers of big data analysis are gradually lowering and data analysis technology being spread out. As the result, big data analysis is expected to be performed by demanders of analysis themselves. Along with this, interest about various unstructured data is continually increasing. Especially, a lot of attention is focused on using text data. Emergence of new platforms and techniques using the web bring about mass production of text data and active attempt to analyze text data. Furthermore, result of text analysis has been utilized in various fields. Text mining is a concept that embraces various theories and techniques for text analysis. Many text mining techniques are utilized in this field for various research purposes, topic modeling is one of the most widely used and studied. Topic modeling is a technique that extracts the major issues from a lot of documents, identifies the documents that correspond to each issue and provides identified documents as a cluster. It is evaluated as a very useful technique in that reflect the semantic elements of the document. Traditional topic modeling is based on the distribution of key terms across the entire document. Thus, it is essential to analyze the entire document at once to identify topic of each document. This condition causes a long time in analysis process when topic modeling is applied to a lot of documents. In addition, it has a scalability problem that is an exponential increase in the processing time with the increase of analysis objects. This problem is particularly noticeable when the documents are distributed across multiple systems or regions. To overcome these problems, divide and conquer approach can be applied to topic modeling. It means dividing a large number of documents into sub-units and deriving topics through repetition of topic modeling to each unit. This method can be used for topic modeling on a large number of documents with limited system resources, and can improve processing speed of topic modeling. It also can significantly reduce analysis time and cost through ability to analyze documents in each location or place without combining analysis object documents. However, despite many advantages, this method has two major problems. First, the relationship between local topics derived from each unit and global topics derived from entire document is unclear. It means that in each document, local topics can be identified, but global topics cannot be identified. Second, a method for measuring the accuracy of the proposed methodology should be established. That is to say, assuming that global topic is ideal answer, the difference in a local topic on a global topic needs to be measured. By those difficulties, the study in this method is not performed sufficiently, compare with other studies dealing with topic modeling. In this paper, we propose a topic modeling approach to solve the above two problems. First of all, we divide the entire document cluster(Global set) into sub-clusters(Local set), and generate the reduced entire document cluster(RGS, Reduced global set) that consist of delegated documents extracted from each local set. We try to solve the first problem by mapping RGS topics and local topics. Along with this, we verify the accuracy of the proposed methodology by detecting documents, whether to be discerned as the same topic at result of global and local set. Using 24,000 news articles, we conduct experiments to evaluate practical applicability of the proposed methodology. In addition, through additional experiment, we confirmed that the proposed methodology can provide similar results to the entire topic modeling. We also proposed a reasonable method for comparing the result of both methods.