• Journal of Microbiology and Biotechnology
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• 제16권1호
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• pp.153-157
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• 2006

A soil metagenomic library was constructed using an E. coli-fosmid cloning system with environmental DNAs extracted from Kwangreung forest topsoil. We targeted the genes involved in the biosynthesis of bacterial polyketides. Initially, a total of 36 clone pools (10,800 clones) were explored by the PCR-based method using the metagenomic DNAs from each pool and a degenerate primer set, which has been designed based on the highly conserved regions among ketoacyl synthase (KS) domains in actinomycete type I polyketide synthases (PKS Is). Six clone pools were tentatively selected as positive and further examined through a hybridization-based method for selecting a fosmid clone containing PKS I genes. Colony hybridization was performed against fosmid clones from the 6 positive pools, and finally 4 clones were picked out and confirmed to contain the conserved DNA fragment of KS domains. In this study, we present a simple and feasible sorting method for a desired clone from metagenomic libraries.

• 한국동물위생학회지
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• 제43권1호
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• pp.1-6
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• 2020

Unlike previous studies that reported the infection rates of Dirofilaria immitis in companion dogs, D. immitis genes were tested directly on mosquitoes to see how many mosquitoes actually carry larvae. Mosquito samples were collected from six parks in Incheon from March to August 2018. A total of 18,589 mosquitoes was collected, classified by type and then made 575 sample pools based on 50 mosquitoes. The PCR method was used to detect Dirofilaria immitis genes of sample pools. Dirofilaria immitis genes were detected in 7 of the 575 pools, and these positive mosquito samples were collected in 4 out of the 6 parks. The types of detected mosquitoes were Aedes dorsalis and Ochlerotatus koreanus which have been identified to act as a vector for heart worm propagation in Incheon. Based on these results, it was concluded that D. immitis genes were found in mosquitoes in the neighborhood park.

• BMB Reports
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• 제38권5호
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• pp.555-562
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• 2005

Single nucleotide polymorphisms (SNPs) are becoming the most common type of markers used in genetic analysis. In the present report a SNP has been chosen to test the applicability of Real Time PCR to discriminate and quantify SNPs alleles on DNA pools. Amplification Refractory Mutation System (ARMS) and Mismatch Amplification Mutation Assay (MAMA) has been applied. Each assay has been pre-validated testing specificity and performances (linearity, PCR efficiency, interference limit, limit of detection, limit of quantification, precision and accuracy). Both the approaches achieve a precise and accurate estimation of the allele frequencies on pooled DNA samples in the range from 5% to 95% and don't require standard curves or calibrators. The lowest measurement that could be significantly distinguished from the background noise has been determined around the 1% for both the approaches, allowing to extend the range of quantifications from 1% to 99%. Furthermore applicability of Real Time PCR assays for general diagnostic purposes is discussed.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 1993년도 수공학연구발표회논문집
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• pp.175-182
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• 1993

The complex nature of low flow transport and tranformation of nonconservative pollutants in natural streams with pools and riffles has been investigated using a numerical solution of a proposed mathematical model that is based on a set of mass balance equations describing hydrodynamic processes (advection, dispersion, and mass exchange mechanicms in streams and in storage zones) and chemical processes (reaction or decay). In this study, a mathematical model (named "Storage-Transformation Model") has been developed to predict adequately the non-Fickian nature of mixing and transformation mechanisms for decaying substances in natural streams under low flow conditions. Comparisons between the concentration-time curves predicted usingthe proposed model and the measured stream data shows that the Storage-Transformation Model yields better agreements in the goneral shape, peak concentration and time to peak than the 1-D dispersion model. The result of this study also demonstrates the differences between transport in pool-and-riffle streams versus transport in more uniform channels. The proposed model shows significant improvement over the conventional 1-D disperision model in predicting natural mixing and stroage processes in streams through pools and riffles.

• 에너지공학
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• 제25권2호
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• pp.45-51
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• 2016

연구용원자로에서 여러 수조 및 일차냉각계통 내부에 존재하는 냉각재를 정화시키기 위해 설치되는 수조수관리계통은 일차냉각계통 펌프가 정지한 후 원자로에서 발생하는 노심 붕괴열을 제거한다. 또한, 작업수조 내의 조사물과 사용후핵연료저장조 내에 저장된 사용후핵연료에서 발생하는 열을 제거하여 수조수의 온도를 제한 값 이내로 유지하는 기능도 수행한다. 본 연구에서는 수조수관리계통의 설계와 운전 방법을 설계 초기단계에서 결정하기 위해서 상용프로그램인 Flowmaster를 이용한 전산해석방법으로 수조수관리계통의 열교환기를 설계하고, 각 수조수의 온도를 시간에 따라 예측하였다.

• Nuclear Engineering and Technology
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• 제52권1호
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• pp.27-36
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• 2020

Natural convection and thermal stratification phenomena are found in large water pools that are being used as heat sinks for decay heat removal from the reactor core using passive heat removal systems. In this study, the two-phase (water and air) natural convection and thermal stratification phenomena with conjugate heat transfer in the rectangular enclosure were investigated numerically using ANSYS Fluent 17.2 code. The transient numerical simulations of these phenomena in the full-scale computational domain of the experimental facility were performed. Generation of water vapour bubbles around the heater rod and evaporation phenomena were included in this numerical investigation. The results of numerical simulations are in good agreement with experimental measurements. This shows that the natural convection is formed in region above the heater rod and the water is thermally stratified in the region below the heater rod. The heat from higher region and from the heater rod is transferred to the lower region via conduction. The thermal stratification disappears and the water becomes well mixed, only after the water temperature reaches the saturation temperature and boiling starts. The developed modelling approach and obtained results provide guidelines for numerical investigations of thermal-hydraulic processes in the water pools for passive residual heat removal systems or spent nuclear fuel pools considering the concreate walls of the pool and main room above the pool.

• Parasites, Hosts and Diseases
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• 제58권4호
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• pp.445-450
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• 2020

Trombiculid "chigger" mites (Acari) are ectoparasites that feed blood on rodents and another animals. A crosssectional survey was conducted in 7 ecosystems of southern Vietnam from 2015 to 2016. Chigger mites were identified with morphological characteristics and assayed by polymerase chain reaction for detection of rickettsiaceae. Overall chigger infestation among rodents was 23.38%. The chigger index among infested rodents was 19.37 and a mean abundance of 4.61. A total of 2,770 chigger mites were identified belonging to 6 species, 3 genera, and 1 family, and pooled into 141 pools (10-20 chiggers per pool). Two pools (1.4%) of the chiggers were positive for Orientia tsutsugamushi. Ricketsia spp. was not detected in any pools of chiggers. Further studies are needed including a larger number and diverse hosts, and environmental factors to assess scrub typhus.

• 대한임베디드공학회논문지
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• 제16권6호
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• pp.299-305
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• 2021

Dissolved oxygen, pH, and temperature are the most important factors for fish farming because they affect fish growth and mass mortality of the fish. Therefore, fish farm workers must always check all pools on the farm, but this is very difficult in reality. That's why we developed a control system for smart fish farms. This system includes a gateway, sensor gatherers, and a PC program using LabVIEW. One sensor gatherer can cover up to four pools. The sensor gatherers are connected to the gateway in the form of a bus. For the gateway, the ATmega2560 is used as the main processor for communication and the STM32F429 is used as a sub-processor for displaying LCD. For the sensor gatherer, ATmega2560 is used as the main processor for communication. MQTT (Message Queuing Telemetry Transport), RS-485, and Zigbee are used as the communication protocols in the control system. The users can control the temperature and the dissolved oxygen using the PC program. The commands are transferred from the PC program to the gateway through the MQTT protocol. When the gateway gets the commands, it transfers the commands to the appropriate sensor gatherer through RS-485 and Zigbee.

• 한국환경과학회지
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• 제4권4호
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• pp.357-365
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• 1995

수영장에서 염소를 이용한 살균시, 수영장의 물과 공기에서 클로로포름 농도가 증가하고 수영자는 이로 인해 클로로포름에 대한 인체 부담응 받을 수 있다. 본 연구는 40 분 수영으로 인해 야기되는 클로로포름에 대한 인체 부담을 확인하고, 60 분 수영 후에 시간에 따라 수영자의 호흡내 클로로포름의 농도가 변화하는 것을 평가하였다. 이 실험을 위해서 수영장의 물과 공기의 클로로포름 농도도 측정되었다. 인체 부담 확인을 위한 연구에서, 수영장 물과 공기내의 클로로포름 농도 범위는 각각 18.1 에서 25.3 ${\mu}g/l$ 및 30.9 에서 60.7 ${\mu}g/m^3$ 이였다. 40분간의 수영으로 인한 호기내의 클로로포름 농도는 수영 전의 호기 농도에 비해 64 에서 266 배 가량 높게 나타났다.수영전의 호기 농도 범위가 0.07 에서 0.19 ${\mu}g/m^3$ 인 반명에, 40분간의 수영 후 호기 농도 범위는 10.5 to 21.3 ${\mu}g/m^3$ 로 나타났다. 또한, 수영 후의 호기 농도가 동일한 날에 방문한 피실험자들간에 서로 다르게 나타났다. 60분간의 수영 중에 수영자의 호흡내 클로로포름 농도는 점진적으로 증가하였고, 수영 5 분 동안은 급격히 감소하다가 그 이후로는 천천히 감소하여 마침내 수영 후 1-2 시간에는 배경 농도에 접근하였다.

• Parasites, Hosts and Diseases
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• 제52권2호
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• pp.221-224
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• 2014

Larvae, nymphs, and adult stages of 3 species of ixodid ticks were collected by tick drag methods in Seoul during June-October 2013, and their infection status with severe fever with thrombocytopenia syndrome (SFTS) virus was examined using RT-PCR. During the period, 732 Haemaphysalis longicornis, 62 Haemaphysalis flava, and 2 Ixodes nipponensis specimens were collected. Among the specimens of H. longicornis, the number of female adults, male adults, nymphs, and larvae were 53, 11, 240, and 446, respectively. Ticks were grouped into 63 pools according to the collection site, species, and developmental stage, and assayed for SFTS virus. None of the pools of ticks were found to be positive for SFTS virus gene.