• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.175-178
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• 2004

Little study has been published specifically addressing the dynamics of nitrate reducing bacteria (NBR) during the bioremediation of nitrate-contaminated aquifer. In our previous study we successfully quantified fumarate-enhanced microbial nitrate reduction rate in a nitrate-contaminated aquifer by using a series of single-well push-pull tests (PPTs). In this study we analyzed the suspended population during PPTs. To monitor changes in the microbial community, PCR amplification of 16S rDNA genes and denaturing gradient gel electrophoresis (DGGE) were used to study the dynamics of the bacterial community in detail. Before the stimulation of NBR, the dominant DGGE bands obtained by PCR were affiliated with V-Proteobacteria consisting of Acinetobacter spp. and Pseudomonas fluorescens. However, as NBR biostimulation proceeded, the dominant patterns of DGGE bands changed, and they were affiliated with Azoarcus denitrificans Td-3 and Flavobacterium xanthum. Azoarcus denitrificans Td-3 is known to completely reduce nitrate to nitrogen gas. The series of single-well push-pull tests in this study should prove useful for conducting rapid, low-cost feasibility assessments for in situ denitrification and provide important information about which microorganisms play a key role in bioremediation of a nitrate contaminated aquifer.

• Bulletin of the Korean Chemical Society
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• 제30권2호
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• pp.429-434
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• 2009

The OH($X^2{\Pi},\;{\nu}$"=0, 1) internal state distributions from the reaction of electronically ground state oxygen atoms with HSi$Cl_3$ were measured using laser-induced fluorescence. The ground-state O$(^3P_J)$ atoms with kinetic energies above the reaction barrier were produced by photolysis of N$O_2$ at 355 nm. The OH product revealed strong vibrational population inversion, P(${\nu}$"=1)/P(${\nu}$"=0) = 4.0 ${\pm}$ 0.6, and rotational distributions in both vibrational states exhibit substantial rotational excitations to the limit of total available energy. However, no preferential populations in either of the two $\Lambda$ doublet states were observed from the micropopulations, which supports a mechanism involving a direct abstraction of hydrogen by the atomic oxygen. It was also found that the collision energy between O and HSi$Cl_3$ is effectively coupled into the excitation of the internal degrees of freedom of the OH product ($$ = 0.62, and $<\;f_{rot}>$ = 0.20). The dynamics appear consistent with expectations for the kinematically constrained reaction which supports the reaction type, heavy + light-heavy $\rightarrow$ heavy-light + heavy (H + LH′ $\rightarrow$ HL + H′). The dynamics of oxygen atom collision with HSi$Cl_3$ are discussed in comparison to those with Si$H_4$.

• Journal of Veterinary Science
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• 제22권5호
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• pp.71.1-71.12
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• 2021

Background: African swine fever (ASF) is a hemorrhagic fever occurring in wild boars (Sus scrofa) and domestic pigs. The epidemic situation of ASF in South Korean wild boars has increased the risk of ASF in domestic pig farms. Although basic reproduction number (R₀) can be applied for control policies, it is challenging to estimate the R₀ for ASF in wild boars due to surveillance bias, lack of wild boar population data, and the effect of ASF-positive wild boar carcass on disease dynamics. Objectives: This study was undertaken to estimate the R₀ of ASF in wild boars in South Korea, and subsequently analyze the spatiotemporal heterogeneity. Methods: We detected the local transmission clusters using the spatiotemporal clustering algorithm, which was modified to incorporate the effect of ASF-positive wild boar carcass. With the assumption of exponential growth, R₀ was estimated for each cluster. The temporal change of the estimates and its association with the habitat suitability of wild boar were analyzed. Results: Totally, 22 local transmission clusters were detected, showing seasonal patterns occurring in winter and spring. Mean value of R₀ of each cluster was 1.54. The estimates showed a temporal increasing trend and positive association with habitat suitability of wild boar. Conclusions: The disease dynamics among wild boars seems to have worsened over time. Thus, in areas with a high elevation and suitable for wild boars, practical methods need to be contrived to ratify the control policies for wild boars.

• Animal Bioscience
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• 제37권1호
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• pp.74-83
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• 2024

Objective: Mitragyna speciosa Korth is traditionally used in Thailand. They have a high level of antioxidant capacities and bioactive compounds, the potential to modulate rumen fermentation and decrease methane production. The aim of the study was to investigate the different levels of microencapsulated-Mitragyna leaves extracts (MMLE) supplementation on nutrient degradability, rumen ecology, microbial dynamics, and methane production in an in vitro study. Methods: A completely randomized design was used to assign the experimental treatments, MMLE was supplemented at 0%, 4%, 6%, and 8% of the total dry matter (DM) substrate. Results: The addition of MMLE significantly increased in vitro dry matter degradability both at 12, 24, and 48 h, while ammonia-nitrogen (NH₃-N) concentration was improved with MMLE supplementation. The MMLE had the greatest propionate and total volatile fatty acid production when added with 6% of total DM substrate, while decreased the methane production (12, 24, and 48 h). Furthermore, the microbial population of cellulolytic bacteria and Butyrivibrio fibrisolvens were increased, whilst Methanobacteriales was decreased with MMLE feeding. Conclusion: The results indicated that MMLE could be a potential alternative plant-based bioactive compound supplement to be used as ruminant feed additives.

• 농업과학연구
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• 제45권1호
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• pp.120-127
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• 2018

The rural labor force has gradually been decreasing due to the decrement of the farm population and the increment of the aging population. To solve these problems, it is necessary to develop and study autonomous agricultural machinery. Therefore, analyzing the dynamic behavior of vehicles in an autonomous agricultural environment is important. Until now, most studies on agricultural machinery, especially on ground vehicle dynamics, have been done by field tests. However, these field test methods are time consuming and costly with seasonal restrictions. A research method that can replace existing field test methods by using simulations is needed. In this study, we did basic research analyzing the effect of the travelling speed of a tractor on tire slip using simulation software. A tractor simulation model was developed based on field conditions following a straight path. The simulation was done for three ranges of speed: 20 - 30 km/h (considered the normal travelling speed range), 6 - 8 km/h (considered the plow tillage speed range) and 2 - 4 km/h (considered the rotary tillage speed range). The results of the simulation show that the slip ratio and slip angle values tended to increase as the traveling speed range of the tractor decreased. From the simulation results, it can be concluded that at low tractor speeds, it becomes more difficult to control the vehicle path. In future research, simulations will be done with various work environments such as a curved path as well as with various friction coefficient conditions, and the simulation results will be experimentally verified by applying them to an agricultural tractor.

• The Korean Journal of Ecology
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• 제22권2호
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• pp.69-77
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• 1999

Secondary vegetation. the holistically integrated system of nature and human being, is the complicated ecosystem that is composed of natural and man-created factors. Understanding the ecological function of secondary vegetation supplies us many important informations for sustainable landscape management and ecological restoration planning. In this research, we tried to examine the shape effect of vegetation patch on early structure of populations of pine and oaks. Moreover. we also tried to clarify the ecological functions of patch edge by exploring the patch effect on germination using patch index. In addition, we present the landscape structure of man -made vegetation of our study area, and setting experimental design of research. Vegetation landscape of study area is typical human disturbed landscape mainly composed of disturbance patches. Vegetation types of graveyard and managed pine forest were controlled by periodically repeated management. However, current seedlings of pine occurred well at both vegetation types. Presence of both saplings were more controlled in managed pine forest (PDM) and graveyard (G) than those of undergrowth (PD) and forest edge (FE) with canopy trees. The number of pine seedlings increased with patch size and patch perimeter. That of oak seedlings was, however, not significantly different. Larger graveyards provided higher light availability for germination of pine seedlings. We think, however, most seedlings of both species in the large sized graveyards without shade will die more easily than that of small sized ones before rainy summer. Relationships between patch shape and germination of two woody species cannot be exactly explained enough yet in these results. More informations on spatial interaction of the total species with differently sized patches are necessary to solve the concept of patch effect on species colonization.

• Asian-Australasian Journal of Animal Sciences
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• 제33권5호
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• pp.763-769
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• 2020

Objective: The experiment was conducted to study the effect of rambutan (Nephelium lappaceum) fruit peel powder (RP) on feed consumption, digestibility of nutrients, ruminal fermentation dynamics and microbial population in Thai breed cattle. Methods: Four, 2-year old (250±15 kg) beef bull crossbreds (75% Brahman×25% local breed) were allotted to experimental treatments using a 4×4 Latin square design. Four dietary supplementation treatments were imposed; non-supplementation (control, T1); supplementation of RP fed at 2% of dry matter intake (DMI) (low, T2); supplementation of RP fed at 4% of DMI (medium, T3) and supplementation of RP fed at 6% of DMI (high, T4). All cattle were given a concentrate supplement at 1% of body weight while Napier grass was provided as a free choice. Results: The findings revealed that RP supplementation did not negatively affect (p>0.05) DMI of Napier grass, while RP intake and total DMI were the greatest in the RP supplementation at 4% and 6% DMI. Nevertheless, the nutrients (dry matter, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber) digestibilities were not changed in the RP supplementation groups. Rumen fermentation parameters especially those of total volatile fatty acids, acetate and butyrate were not significantly changed. However, the propionate concentration was remarkably increased (p<0.05) in the RP supplementation. Notably, the ratio of acetate to propionate, the number of protozoa, as well as the methane estimation were significantly reduced in the RP supplemented groups (4% and 6% of DMI), while the counts of bacteria was not altered. Conclusion: Supplementation of RP (4% of DMI) improved rumen propionate production, reduced protozoal population and methane estimation (p<0.05) without a negative effect on feed consumption and nutrients total tract digestibilities in beef cattle. Using dietary rambutan fruit peel powder has potential promise as a rumen regulator.

• 유기물자원화
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• 제13권2호
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• pp.98-106
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• 2005

지렁이 사육상으로부터 지렁이를 분리, 수확할 수 있는 지렁이 유인장치를 개발하기 위해서 사육상에서의 지렁이 개체군 동태, 유인물질 및 유인틀내 철망의 mesh 크기, 덮개재질 등에 따른 지렁이 유인효율을 조사하였다. 지렁이 사육상에서 줄지렁이의 최고밀도는 약 $5kg/m^2$이었으며 최고밀도 도달한 이후에는 $4.4{\sim}5.0kg/m^2$의 밀도를 유지하였다. 유인틀내 철망의 mesh 크기는 7mm정도가 적정하였으며 유인틀 덮개는 표면은 매끄럽고 수분을 잘 머금을 수 있는 재질이 적당하였다. 유인틀내에 유인제를 사용하는 경우가 사용하지 않는 경우보다 유인효과가 현저히 높았으며, 유인틀내 유인제량이 많을수록, 유인틀 설치 기간이 길어질수록 지렁이 유인량이 많아졌다. 유인제로서는 분쇄된 배껍질이 제지슬러지보다 우수하였는데 이는 유인제내 당도의 차이에 기인하는 것으로 판단된다. 그러나 현장에서 사용할 수 있을 만큼 충분한 량의 배껍질을 공급하기가 어려우므로 그 대용으로서 설탕물(10%)을 유인물질로 이용하는 방안이 제시될 수 있었다.

• Journal of Forest and Environmental Science
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• 제34권1호
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• pp.1-11
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• 2018

We studied natural and plantation forest ecosystem of Sarguja in Chhattisgarh, India in order to understand how vegetation biomass, carbon stock and its allocation patterns vary among the sites. For this, stratified random sampling was opted to measure the different layers of vegetation. Wide floral diversity was found in the natural forest site as compared to the teak stand. Overall, 17 tree species found in natural forest comprising 8 families while in the teak stand 6 species were recorded. In understory strata 23 species were recorded (18 herbs and 5 shrubs) in natural forest whereas in teak stand 20 herb species and 3 shrubs were found. Great variation was also seen in the population dynamics of the different vegetation stratum in concerned sites. The sapling, seedling and herb density was found to be highest in natural stand while tree and shrub density was more in teak stand. Results indicated that stand biomass of the natural site was $321.19t\;ha^{-1}$ while in the teak stand it was $276.61t\;ha^{-1}$. The total biomass of tree layer in plantation site was $245.22t\;ha^{-1}$ and natural forest $241.44t\;ha^{-1}$. The sapling, seedling, shrub and forest floor biomass was found highest under natural forest as compared to the teak plantation site. Carbon stock has similar trend as that of biomass accumulation in natural forest and teak stand. Higher biomass accumulation and carbon stock were recorded in the higher girth class gradation of the population structure. Proper efforts are required to manage these diverse ecosystems to obtain higher biomass and sustainable ecological services.

• 환경생물
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• 제18권4호
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• pp.411-424
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• 2000

연안생태계의 호염성 톡토기와 개미군집의 생물다양성정도와 변동에 대해 알아보기 위해, 주변환경과 식생이 다른 세지역에서 정량채집을 실시하였다. 종조성이나 분포에 영향을 주는 요인을 찾기 위해 pH, 염도 및 전기전도도를 측정하였다. 연구결과 톡토기의 종조성 이나 분포에는 pH와 식생보다도 토성과 염도가 더 큰 영향을 주는 것으로 나타났다. 그러나 개미의 경우는 집을 지을 적당한 장소를 제공해 줄 수 있는 식생과 조수에 의한 침수에 더 큰 영향을 받는 것으로 사료된다. 모든 조사지역에서 조상대가 조간대보다 다양도가 높았으며 조간대중에서는 모래함량이 높은 동호의 상조대에서 가장 높게 나타났다