• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제21권3호
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• pp.143-154
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• 2017

This paper presents the mathematical model for the MERS-CoV outbreak in South Korea, and the optimal control for two intervention strategies (contact, hospitalization) is implemented. After the MERS-CoV outbreak, hospitalizing infected individuals did not help to prevent the spread of infection. However, the intervention to control contact was effective. It was effective the intervention to controlling both of contact and hospitalization of infection population.

• Journal of Yeungnam Medical Science
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• 제34권2호
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• pp.222-230
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• 2017

Background: Varicella is the most common infectious disease reported despite the high vaccination rate. Interventions that target humans are particularly effective for varicella because humans are its only natural host. On the other hand, the existing national varicella surveillance systems lack the information to identify an outbreak. Therefore, a new index to assess varicella outbreaks was developed. Methods: The residential addresses of 2,718 varicella cases reported in Daegu in 2016 were converted to geographic coordinates and the distances between new varicella case and previous cases within 21 days were calculated from the date analyzed. Two cases were considered to be adjacent if the distance between them was less than 1 km. Finally, a proximity index was introduced by dividing the number of adjacent cases by the number of new cases on the date analyzed. Results: First, time-series charts and scatter plots were used to verify that the proximity index reflected the spatial closeness of the different varicella cases. The proximity index is helpful in identifying outbreaks from a list of single varicella cases. In addition, in this study, a new epidemic characteristic of varicella based on the proximity index was shown. Conclusion: The proximity index introduced in this study can be used to determine the likelihood of an outbreak from a single case of varicella, and it can be embedded in a web-based national varicella surveillance system that is currently in operation.

• 통합자연과학논문집
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• 제13권3호
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• pp.105-113
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• 2020

As the COVID-19 outbreak has prolonged, social distancing movements are encouraged and non-face-to-face lifestyle trends are spreading. As a result, it is necessary for general restaurants and small marts to provide delivery services like large-scale distribution companies. Large distribution companies have also suffered significant economic losses from COVID-19 because epidemiological investigations were conducted after the distribution center was closed due to the outbreak of COVID-19 in several large domestic distribution companies. In this thesis, in order to examine whether COVID-19 actually affects distribution companies, we attempt to understand the relationship between the number of confirmed cases per month and the sales share and growth rate by categories of distribution companies.

• 통합자연과학논문집
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• 제13권4호
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• pp.158-169
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• 2020

Modern people live in the age of plastics. It has been widely used due to its easy molding processing, mass production, and excellent durability. However, over-produced plastics for convenience cause plastic disasters and adversely affect the ecosystem. Since the COVID-19 outbreak, the use of single-use plastic waste due to the use of delivery services has increased. The COVID-19 pandemic has caused a plastic pandemic. Currently, domestic recycling policies depend only on recycling collection companies and market prices of recyclable resources. This paper confirms whether the outbreak of COVID-19 has affected the price of plastic waste. It also shows that the price of plastic waste is more unstable than metals with a high recycling rate. This urges businesses to share the cost of recycling on plastic waste, no longer being dependent on market prices for recyclable resources.

• Journal of Nutrition and Health
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• 제56권6호
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• pp.667-682
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• 2023

본 연구는 국민건강영양조사 2019-2020년 자료를 활용하여 한국 남녀 중, 고등학생을 대상으로 coronavirus disease 2019 (COVID-19) 전후의 건강행태, 정신건강 및 영양 상태를 비교하기 위해 수행되었다. 신체계측은 COVID-19 이후 남자 중학생에서 과체중과 비만 비율이 증가하는 경향을 보였으나 유의적인 차이는 아니었다. 건강행태 및 신체, 정신건강을 비교하면 COVID-19 이후 남자 고등학생에서 하루 60분 신체 활동 실천 일수가 줄고 중성지방, 헤모글로빈 수치가 낮아졌다. 남자 중학생은 이완기 혈압과 인슐린농도가 높아지고, 여자 중학생은 공복혈당, 여자 고등학생은 당화혈색소 수치가 낮아졌다. 남녀 중학생에서 COVID-19 이후 스트레스를 조금 느끼거나 거의 없다는 비율이 높았으며 여자 중학생에서는 아침식사 결식률이, 남녀 중, 고등학생 모두에서는 가족과 점심식사를 동반한다는 비율이 높아졌다. COVID-19 이후 남자 중학생은 우유류가, 여자 중학생은 감자류, 야채류, 음료류에서 평균섭취량이 낮으며 전반적으로 영양소 섭취가 부족했음을 알 수 있었다. 영양소 섭취량은 COVID-19 이후 남자 중학생에서 인과 나이아신 섭취량의 감소, 여자 중학생에서 칼륨, 비타민 C 섭취량의 감소, 그리고 여자 고등학생에서는 비타민 C와 리보플라빈의 섭취량이 감소하는 변화를 나타냈다. 위 결과를 통해 COVID-19 팬데믹 상황에서 청소년의 건강상태는 비교적 잘 유지하고 있었으나 신체활동 부족, 식습관 변화, 일부 영양소 섭취 부족이 나타났음을 확인하였다.

• 한국환경과학회지
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• 제32권12호
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• pp.979-985
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• 2023

After the outbreak of COVID-19, the demand for home-enjoyable video games has surged, driven by extended pandemic conditions and resulting in rapid graphic technology advancements. Consequently, games with diverse expression techniques have emerged, captivating players. Virtual Reality (VR) environments predominantly feature natural landscapes, with advancing graphic technology enabling lifelike scenes. The rise in individuals seeking solace through natural elements in games has followed suit. As VR technology and metaverse interest grow, more people are exposed to digital imagery. However, evidence on the influence of graphic expression methods on emotional response to that is lacking. Our study examined user emotional responses, focusing on natural landscapes in digital graphics of games. Analyzing a group of 47 young adults as frequent digital media consumers, we studied reactions to different image styles (Realism, Semi-Realism, Stylized). In the analysis, Realism-style images were perceived the most positively, while emotional responses to natural landscapes with different graphical expressions showed no significant differences. Results suggest that recognizing digital natural landscapes may outweigh expression style impacting the evaluation of digital nature. This study's empirical analysis enhances the understanding of digital nature's application to actual situations.

• 식물병연구
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• 제10권4호
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• pp.209-216
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• 2004

The circular leaf spot of persimmon is occurred almost every place where persimmon is cultivated, especially the disease outbreak severely in southern part of Korea. The disease reveals unusually long incubation period after pathogen invade into leaf tissue and no practical control measure is available once the symptom has appeared. Most of the farmers just follow the suggested spray schedules calculated on the basis of weather condition of ordinary years. Therefore the damages due to circular leaf spot greatly differ year after year. In this article, we tried to describe and summarized the investigation on the circular leaf spot pathogen, Mycosphaerella nawae, related to disease outbreak such as overwintering of pathogen, inoculum formation and spread, incubation period after infection, and secondary inoculum. With the summary of these results, we suggest the disease cycle of circular leaf spot of persimmon. The pathogen overwinters in diseased leaves as mycelial form or pseudoperithecial premodium. The pseudoperitheria become matured in spring as the temperature raise and forms asci and ascospores. The maturation of pseudoperithecia are closely related to the temperatures during March and early April. The ascospores completely mature in early May and the ascospores released when the pseudoperithecia absorbed enough moisture after rainfall. The release of ascospores are diverse greatly with the variation of maturity of pseudoperithecia. Generally the spore start to release from middle of May to early of July. Duration of ascospore release is depend on the weather condition of particular year, especially amount and number of precipitation. The ascospores produced from pseudoperithecia is known to the only inoculum for circular leaf spot disease. But according to the results obtained from our investigations, the conidia formed on the lesions which incited by natural infection. This conidia are infectious to persimmon leaves and formed identical symptom as natural infection. The time of producing secondary inoculum of circular leaf spot of persimmon is considered too late to develop new disease. Generally the importance of secondary inoculum is low but the conidia produced in early September are competent to develop new disease and new infection also significantly affect to harvest of persimmon. The importance of circular leaf spot disease is recognized well to farmers. The approaches to control of the disease should be initiated on the basis of the knowledges of inoculum dynamics and ecology of disease development. The forecasting system for circular leaf spot is need to be developed.

• 한국응용곤충학회지
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• 제53권1호
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• pp.27-34
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• 2014

자연 감염된 담배가루이로부터 곤충병원성진균을 분리 동정하고, 이 균주에 대하여 배양특성, 자연발병 요인, 그리고 주요 온실해충인 담배가루이, 점박이응애, 대만총채벌레에 대한 살충력을 검정하였다. 분리 균주의 형태적 특성은 직립한 분생자병에 윤생으로 호리병 형태의 4-6개 phialide를 지녔고, 분생포자의 크기는 $3.0-3.4{\mu}m$ 이었다. 분리 균주의 rDNA의 ITS영역 염기서열 분석에서 Isaria fumosorosea (AF461747)와는 99%의 높은 염기서열 유사도를 보였다. Potato dextrose agar, Sabouraud maltose agar+yeast extract 그리고 Sabouraud dextrose agar+yeast extract 배지에서 IFs 균주는 $24^{\circ}C$의 SDAY 배양에서 균사 성장이 가장 양호하였으며, $15^{\circ}C$보다는 $35^{\circ}C$의 고온에서 균사 성장이 좋았다. I. fumosorosea IFs-08, -09 균주는 담배가루이에 대하여 각각 96.7, 93.9%의 높은 살충율을 보였으며, 점박이응애(92.0, 84.9%) 그리고 대만총채벌레(84.4, 81.5%)에서도 80-90%정도의 살충율을 보인 반면 KACC로부터 분양받은 Isaria tenuipes, Isaria farinosa, Isaria fumosorosea 균주들은 10-20% 내외의 낮은 살충율을 나타내었다.

• 대한수의학회지
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• 제41권4호
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• pp.505-510
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• 2001

A total of 701 swine sera from 55 swine farms (Mar, 1998 through Feb, 2001) were nation-widely collected for the presence of antibody to porcine parvovirus (PPV) in sows and 30-, 60-, 90-day-old pigs. Sero-prevalence by haemagglutination inhibition assay with guinea pig red blood cells was investigated on the basis of year, region and season, respectively. In general, there was no significant difference with gradual decrease of passive immunity for the sero-prevalence to PPV in sows and 30-, 60-, 90-day-old pigs for the period of 1999 and 2000. However, regional variation was observed in the provinces of Kyonggi, Choongnam and Kyungnam, Natural infection of the virus in 90-day-old pigs was increased during the fall and the winter. Thus, it seems that the natural infection of PPV in growing pigs may be attributed to the increased outbreak of postweaning multisystemic wasting syndorme in co-infection with porcine circoviruses.

• 농업과학연구
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• 제47권1호
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• pp.173-182
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• 2020

Human Astrovirus (HuAstV), known as a waterborne virus, is a group IV positive-sense single-stranded RNA that belongs to Astroviridae. The first outbreak of HuAstV was reported in England in 1975. HuAstV can exist not only among clinical patients but also in various water environments, such as water for agriculture and vegetables. For diagnosis of HuAstV from water samples, a polymerase chain reaction (PCR) system has been developed. However, the PCR-based diagnostic method has problems in field application, such as reaction time, sensitivity and specificity. For this reason, in this study we developed the loop-mediated isothermal amplification assay (LAMP) system, aimed specifically at HuAstV. Three prepared LAMP primer sets were tested by specificity, non-specificity and sensitivity; one LAMP primer set was selected with optimum reaction temperature. The developed LAMP primer set reaction conditions were confirmed at 62℃, and detection sensitivity was 1 fg/μL. In addition, restriction enzyme HaeIII (GG/CC) was introduced to confirm that the LAMP reaction was positive. As a result, selected LAMP primer set was 100 - 1000 times more specific, rapid, and sensitive than conventional-nested PCR methods. For verification of the developed LAMP assay, twenty samples of cDNA from groundwater samples were tested. We expect that the developed LAMP assay will be used to diagnose HuAstV from various samples.