• 한국잡초학회지
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• 제12권3호
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• pp.230-260
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• 1992

The paper was reviewed the research results on weed dynamics and effective control methods in direct-seeded rice crop. Direct seeding method resulted in drastic increment of weed growth compared to transplanting method and also changed in troublesome weed flora. Two to three fold more weeds were harvested at the direct seeded rice and weed flora of dominant species shifted toward $C_4$type grass weeds. Some of the important troublesome weeds in direct seeded rice were Echinochloa crus-galle, Oryza saliva ssp spontanea, Leptochloa chinensis. Setaria viridus. Digitaria adsendens, Sesbania exaltata, Aeschynomene indica, Algae, etc. Yield loss due to weed competiton was about 40-60% for water-seeded and about 70-100% for dry-seeded rice while these for transplanted rice were about 25-35% for mechanical transplanting and about 10-20% for manual transplanting, respectively. Integrated weed management concept was neede to approach weed control effectively. Several cultural technologies were very effective to suppress the weed growth. These were tillage operation, water management, seeding date and seeding rate. Crop residues of barley, rice, wheat, oat and italian ryegrass were also effectivly suppressed the paddy weeds particularly to Potamogeton distiuctus, a perennial broadleaf weed. A pathogen of Epicoccosorus nematosporus identified from Eleocharis kuroguwai was an excellent potential bioagent to control the most troublesome perennial sedge weed of E. Kuroguwai without arising any detrimental effect. The herbicidal efficacy of this pathogen was as high as bentazon herbicide. Plant growth regulator of paclobutrazol (pp-333) was another possible alternative to reduce the herbicide use. In current, herbicide exhibited the most conspicuous results to control weeds in direct-seeded rice even though the application technologies were not fully established. Recommendations for herbicide application were suggested for in both water-and dry-seeded rice in USA, Japan and Korea, respectively. To make better and comprehensive recommendations further studies on weed ecology and herbicide development were emphasized.

• 전자공학회논문지SC
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• 제48권3호
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• pp.30-39
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• 2011

본 연구에서는 수정된 상태변수 의존 비선형 형을 바탕으로 부정합조건 불확실성과 정합조건 외란을 갖는 비선형 시스템의 제어를 위한 새로운 둔감한 비선형 연속 가변구조제어기의 체계적인 설계를 제안한다. 부정합조건 불확실과 정합조건 외란 비선형 시스템을 상태변수 의존 비선형 시스템 형으로 표현한 후 체계적인 둔감한 새로운 제어기 설계를 한다. 대상 시스템의 확장을 위하여 비선형 시스템 함수의 불확정성을 상태변수 의존 항과 비의존 항 두 부분으로 나눈다. 본 비선형 제어는 제어 결과 동특성을 선형으로하기 위하여 그리고 슬라이딩 모드 존재조건을 쉽게 만족시키기 위하여 변환된 선형 슬라이딩 면을 선정한다. 선정된 슬라이딩 면 위에 슬라이딩 존재조건과 폐루프 지수 안정성을 만족하는 제어입력을 제안한다. 정리를 통하여 증명한다. 본 제어의 실용성을 위하여 가변구조제어의 내재된 특성인 제어입력의 불연속성을 극적으로 개선한다. 설계 예와 시뮬레이션 연구를 통하여 제안된 제어기의 유용성을 입증한다.

• The Korean Journal of Ecology
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• 제18권3호
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• pp.307-321
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• 1995

Division of ecoregions having respective functions was attempted through quantitative and qualitative analysis on vegetation diversity, and heterogeneity and on soil environment of the study sites. Field research was carried out in a square of 81 ㎢ around Andongpo (126°38'E, 37°30'N), Kimpo-gun, Kyonggi provice. Conventional methods applied are as follows: classical syntaxonomy by the Zurich-Montpellier School, interpolation method to determine the degree of diversity, heterogeneity and distribution pattern of vegetation, and correlation analysis between soil properties and plant communities. 41 plant communities were identified and composed of 6 forests, 4 mantle and 31 herb communities including 6 saltmarsh plant communities. In a mesh, number of plant communities was highly correlated to the number of species. The highest number of plant community and species was 25 communities·km-2·mesh-1 and 381 species· km-2·mesh-1 ,and the highest value of vegetation heterogeneity was 28.1 species· community-1·mesh-1. Their lowest numbers were 4 communities·km-2·mesh-1. and 28 species·km-2·mesh-1. and 7 species·community-1·mesh-1, respectively. Contour map on vegetation diversity and heterogeneity enabled us to establish two regions; coastal and inland vegetation. Isoline 〔150〕,〔10〕and〔10〕and〔15〕on the species diversity, the community diversity and the vegetation heterogeneity, respectively, were regarded as ecolines in the study area. Cl- content was recognized as the most important factor from correlation analysis between soil properties. Ordination of sites indicated that the study area be divided into two edaphic types: inland and coastal habitats. It was considered that the extent of desalinization in soil played a major role in determining the species composition in the reclamed area. By matching edaphic division of habitats with division of vegetation structures, designation of ecoregion was endorsed. The approach of current study was suggested as an effective tool to implement an assessment of the vegetation dynamics by the disparity of natural environment and anthropogenic interferences.

• Journal of Ecology and Environment
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• 제33권4호
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• pp.289-298
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• 2010

A number of characteristics of the Lake H$\ddot{o}$vsg$\ddot{o}$l watershed, such as the lake's location at the edge of the Central Asian continuous permafrost zone, provide a unique opportunity to evaluate possible anthropogenic impacts in this remote area in northern Mongolia. In this study, we compared stream solute concentrations in six sub-watersheds in the Lake H$\ddot{o}$vsg$\ddot{o}$l watershed. Water samples were collected during the summer months between 2003 and 2005. Concentrations of $Cl^-$ ranged from 9.8 to $51.3\;{\mu}mol/L$; average nitrate concentrations were very low and ranged from undetectable to $1.1\;{\mu}mol/L$ and average ${SO_4}^{2-}$ concentration at sampling stations with minimal animal grazing ranged from 66 to $294\;{\mu}mol/L$. Average dissolved organic carbon (DOC) concentrations ranged from 642 to $1,180\;{\mu}mol$ C/L. We did not find statistically significant differences in DOC concentrations among the six streams, although DOC concentrations tended to be higher in the two northernmost streams, possibly related to differences in the active layer above the permafrost. Dissolved organic nitrogen (DON) concentrations were correlated with DOC concentration, and followed the same spatial pattern as those for DOC. In streams in this remote watershed, total dissolved nitrogen was made up of mostly organic N, as has been found for other regions distant from anthropogenic N sources. Overall, these results suggest that future research on the dynamics of DOC and DON in this watershed will be especially insightful in helping to understand how changes in climate and land use patterns will affect transformations, retention, and export of dissolved organic matter within these sub-watersheds in the Lake H$\ddot{o}$vsg$\ddot{o}$l region.

• Journal of Forest and Environmental Science
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• 제34권5호
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• pp.359-375
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• 2018

The long term ecological effects have been reported in natural forest ecosystem due to various anthropogenic disturbances, especially in tropics of the world. The present study was carried out in the sanctuary area of central India to assess the changes on litter biomass, litterfall pattern and soil attributes under different disturbance regimes. The study area includes three forest circles i.e., Bhoramdeo, Jamunpani and Salehwara each comprising three disturbances regimes viz., high, medium and low severity of biotic pressure. A noticeable variation and impact were recorded in different sites. The impact varies significantly from least disturbed sites to highly disturbed sites across the circle and among different disturbances level. The seasonal mean total forest floor biomass across the forest circles varied from 2.18 to $3.30t\;ha^{-1}$. It was found highest under lightly disturbed site and lowest under heavily disturbed site. Total litterfall varied from 5.11 to $7.06t\;ha^{-1}\;yr^{-1}$ across the forest circle. Lowest litterfall was recorded at heavily disturbed site while highest in lightly disturbed site. Annual turnover of litter varied from 69-73% and the turnover time ranged between 1.37-1.45 years. The turn over time was higher for heavily disturbed site and lower for lightly disturbed site. The heavily disturbed site of all the circle showed the sandy loam soil texture, whereas moderately and lightly disturbed site comprised of sandy loam, sandy clay loam and clay soil texture, respectively. The bulk density decreases from heavily disturbed site to lightly disturbed site and the pH of soils ranged from 5.57-6.89 across the circle. Across the circle the total soil nitrogen ranged from 0.12-0.21%, phosphorus from 10.03-24.00 kg and Potassium from $139.88-448.35kg\;ha^{-1}$, respectively. Our results demonstrate that anthropogenic disturbances regime significantly influences forest floors in terms of mass, composition and dynamics along with litterfall rate and soil properties.

• Journal of Ecology and Environment
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• 제35권3호
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• pp.177-188
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• 2012

We analyzed crown development in Aucuba japonica Thunb. var. japonica resulting from the responses of phytoelements to habitat light conditions over a long period of time. Over the years, the degree of extension unit (EU) dimorphism and the degree of anisophylly were higher under shaded conditions than in brighter conditions. An overall temporally increasing pattern in the degree of EU dimorphism was found while no clear-cut trend was found in the case of anisophylly. EU length and number of leaves per EU co-varied in a spatio-temporal context. The number of terminal buds and their sizes acted as the key initiators of morphological differences of phytoelements which were further amplified following bud break. Leaf area density was displayed mostly in the apex peripheral layer of the crown and the apex layer received most of the incident light. There was a tradeoff between annual leaf production and mean leaf size. Depending on the heterogeneity of irradiance level within a crown, correlative growth inhibition caused higher EU mortality at brighter sites. Due to high mortality, shorter EUs had a mere role in the construction of structural framework of the crown except for the formation of some gaps. There was a strong convergence of EU dimorphism, anisophylly, EU extension growth and variations in leaf size towards formation of functional crown to reduce potential self-shading. Depending on the irradiance level, Aucuba japonica Thunb. var. japonica showed two different modes of crown expansion. At the brighter sites, individual crown expansion was progressive while at the darker sites, individual crown expanded in a diminishing manner and maintained a stable size. A plant's "growth diminishing phase" appeared earlier at shaded sites than brighter sites.

• 한국경제지리학회지
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• 제15권3호
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• pp.376-389
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• 2012

이민자 집단에 있어 자영업은 생존과 사회경제적 지위 상승의 중요한 수단이다. 지리학적 관점에서는 이민자들의 주거 집중이 이민자 자영업이 성장하는데 중요한 역할을 한다고 보아 왔다. 하지만 최근 이민자들의 거주지가 분산되어 집거권의 역할이 축소될 가능성이 점쳐 지고 있다. 본 연구는 이민자들의 주거 분산에 따른 자영업에 대한 집거권이 행하는 역할이 어떻게 변화해 가는지 시카고 대도시권에 거주하고 있는 한국인 자영업자들을 사례로 분석하였다. 먼저 Public Use Microdata Sample(PUMS) 통계자료를 통해 한인 자영업의 전반적인 변화상을 점검하였다. 주거 분산에 대한 한인 자영업자들의 반응과 대응을 설문조사를 통해 살펴보았다. 반응이라는 측면에서 자영업자들을 '영향이 있었다'는 그룹과 '영향이 별로 없었다'는 그룹으로 나누고 각각의 특성이 고객확보, 노동력수급, 자재수급, 사업정보획득, 그리고 사업경험이라는 측면에서 서로 다르다고는 것이 밝혀졌다. 두 그룹이 민족네트워크에 의존하는 정도와 활용하는 방법에서 상이하여 그러한 반응을 보인 것으로 판단되었다. 본 연구는 이민자 기업가주의의 발흥에 있어 주거 집중의 중요성은 해당 자영업의 민족적 네트워크의 의존도와 활용방법에 달려있다는 점을 밝혔다.

• 천문학회지
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• 제53권5호
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• pp.103-115
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• 2020

We analyze the spatially resolved kinematics of gas and stars for a sample of ten hidden type 1 AGNs in order to investigate the nature of their central sources and the scaling relation with host galaxy stellar velocity dispersion. We select our sample from a large number of hidden type 1 AGNs, which are identified based on the presence of a broad (full width at half maximum ≳1000 km s^-1) component in the Hα line profile and which are frequently mis-classified as type 2 AGNs because AGN continuum and broad emission lines are weak or obscured in the optical spectral range. We used the Blue Channel Spectrograph at the 6.5-m Multiple Mirror Telescope to obtain long-slit data with a spatial scale of 0.3 arcsec pixel^-1. We detected broad Hβ lines for only two targets; however, the presence of strong broad Hα lines indicates that the AGNs we selected are all low-luminosity type 1 AGNs. We measured the velocity, velocity dispersion, and flux of stellar continuum and gas emission lines (i.e., Hβ and [O III]) as a function of distance from the center. The spatially resolved gas kinematics traced by Hβ or [O III] are generally similar to the stellar kinematics except for the inner center, where signatures of gas outflows are detected. We compare the luminosity-weighted effective stellar velocity dispersions with the black hole masses and find that our hidden type 1 AGNs, which have relatively low back hole masses, follow the same scaling relation as reverberation-mapped type 1 AGN and more massive inactive galaxies.

• 한국CDE학회논문집
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• 제17권3호
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• pp.149-155
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• 2012

The ankle over-pronation causes the mechanical overloading transferred to proximal areas (i.e. knees or hips) over time. Thus, the over-pronation is recognized as a contributory factor in a wide variety of musculo-skeletal pathologies in lower extremities. Commonly, over-pronated ankles are treated using specially designed insoles that support medial heels and correct the posture of lower limbs. However, the biomechanical effects of the insoles are not yet fully understood, so there still are controversies whether such insoles really have clinical significance. In this study, in order to verify the effects of insoles and determine the best shape of the insoles, we examined how the medio-lateral knee joint reaction force changes due to insole conditions through a case study about a subject. As a result, it is revealed that the medial heel post, which drastically reduced the peak medio-lateral knee joint reaction force, has significant effects on the gait of the over-pronated patients. However, in case that the arch support is combined together, the positive effect of the medial heel post may rather decrease.

• BMB Reports
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• 제49권5호
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• pp.245-246
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• 2016

The level and activity of critical regulatory proteins in cells are tightly controlled by several tiers of post-translational modifications. HIF-1α is maintained at low levels under normoxia conditions by the collaboration between PHD proteins and the VHL-containing E3 ubiquitin ligase complex. We recently identified a new physiologically relevant mechanism that regulates HIF-1α stability in the nucleus in response to cellular oxygen levels. This mechanism is based on the collaboration between the SET7/9 methyltransferase and the LSD1 demethylase. SET7/9 adds a methyl group to HIF-1α, which triggers degradation of the protein by the ubiquitin-proteasome system, whereas LSD1 removes the methyl group, leading to stabilization of HIF-1α under hypoxia conditions. In cells from knock-in mice with a mutation preventing HIF-1α methylation (Hif1α^KA/KA), HIF-1α levels were increased in both normoxic and hypoxic conditions. Hif1α^KA/KA knock-in mice displayed increased hematological parameters, such as red blood cell count and hemoglobin concentration. They also displayed pathological phenotypes; retinal and tumor-associated angiogenesis as well as tumor growth were increased in Hif1α^KA/KA knock-in mice. Certain human cancer cells exhibit mutations that cause defects in HIF-1α methylation. In summary, this newly identified methylation-based regulation of HIF-1α stability constitutes another layer of regulation that is independent of previously identified mechanisms.