• 생태와환경
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• 제49권4호
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• pp.271-278
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• 2016

Forest clear-cutting operations influence biodiversity through habitat changes and food resource availability for inhabitant species. This study examined the effects of clear-cutting on forest arthropod communities. Arthropods were collected from two different forest treatment areas (clear-cut and control) in summer and autumn. In each treatment area, arthropods were sampled from both crown and ground surfaces using sweeping and pitfall trap methods, respectively. Then, the taxonomic order of the collected arthropod specimens was easily identified. Results indicate that arthropod abundance and number of taxa present were higher at ground surface than at crown levels in both clear-cut and control areas. At crown level, more homopteran species were present in clear-cut areas than in control areas in summer. At ground surface, populations of Isopoda and Opiliones were higher in control areas than in clear-cut areas, whereas numbers of Araneae, Orthoptera, and Hymenoptera were greater in clear-cut areas. Cluster analysis and principal component analysis showed distinct differences between clear-cut and control communities at crown level in summer and at ground surface in autumn. Thus, our results indicate that clear-cutting significantly influences arthropod communities, and higher taxa are valuable for conducting rapid biological assessments of ecosystem disturbances.

• 한국산림과학회지
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• 제98권5호
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• pp.609-617
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• 2009

This study was conducted to investigate ecological indicators of forest degradation after forest fire and clear-cutting in the Siberian larch (Larix sibirica Ledeb.) stand of Mongolia. The species abundance and biodiversity indices were higher in burned and clear-cut stands than those of reference stand, but boreal understory species, such as Vaccinium vitis-idaea, Pyrola incarnata, Linnea borealis and Maianthemum bifolium, completely disappeared and was replaced by sedge species, such as Carex duriuscula, C. lanceolata, C. pediformis, Poa attenuata and P. pratensis. During the research period, temperature increased by an average of $1.6^{\circ}C$ in burned stand and $1.7^{\circ}C$ in clear-cut stand compared to reference stand, but RH sharply decreased up to 15.7% in clear-cut stand. This result indicates that Larix sibirica stand became warmer and drier after forest fire and clear-cutting, and contributed to the abundance of sedge and grass species in the understory. Moreover, intense occupation of tall sedge grass after forest fire and clear-cutting had a vital role as obstacle on natural regeneration of Larix sibirica. The similarity of species composition between reference and burned stands was higher (73.6%) than between reference and clear-cut stands (63.8%). Soil moisture significantly decreased after forest fire and clear-cutting, and the extent of decrease was more severe in the clear-cut stand. The chemical properties at soil organic layer were significantly affected by forest fire and clear-cutting but not the mineral horizons. Inorganic nitrogen of the forest floor significantly decreased in the clear-cut stand ($1.1{\pm}0.4mg{\cdot}kg^{-1}$) than that of the burned ($4.5{\pm}2.3mg{\cdot}kg^{-1}$) and reference stands ($5.0{\pm}2.3mg{\cdot}kg^{-1}$). Available P of the forest floor significantly increased after fire, whereas it decreased after clear-cutting. These results indicate that existence of boreal understory vegetation, and changes in soil moisture and available P are distinct attributes applicable as ecological indicators for identifying forest degradation in Mongolia.

• 한국산림과학회지
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• 제97권2호
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• pp.181-186
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• 2008

Even small changes in phosphorus concentrations in stream water could cause eutrophication because of very low level of phosphorus concentrations in natural waters. I investigated the impact of strip cut and clear cut on phosphorus concentrations in stream water at the Hubbard Brook Experimental Forest and investigated stream water phosphorus concentrations as a function of flow rate and season (as well as cutting history). Mean phosphate concentrations in the control (undisturbed forest) increased $1.9{\mu}g\;L^{-1}\;to\;2.6{\mu}g\;L^{-1}$, while strip cut treatment increased phosphate concentrations in stream water $2.2{\mu}g\;L^{-1}\;to\;3.7{\mu}g\;L^{-1}$ during the same period. There was no significant effect of clear cut treatment on phosphate concentrations in stream water. No relationships were found between discharge rate and phosphate concentrations, but the magnitude of fluctuation were increased during two decades in undisturbed forest: $1-5{\mu}g\;L^{-1}$ from 1963 to 1975 and $1-12{\mu}g\;L^{-1}$ from 1983 to 1995. Based on this study, forest harvests with buffer zone will not make a problem by imported phosphate to cause eutrophication in natural water.

• Journal of Gastric Cancer
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• 제23권3호
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• pp.451-461
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• 2023

Purpose: Endoscopic submucosal dissection (ESD) is an effective treatment for early gastrointestinal neoplasms. However, this is a time-consuming procedure requiring various devices. This study aimed to evaluate the efficacy and safety of the ClearCut^TM Knife H-type, which is an integrated needle-tipped and insulated-tipped (IT) knife. Materials and Methods: Between July 2020 and September 2021, 99 patients with gastric epithelial neoplasms scheduled for ESD at three tertiary care hospitals were randomly assigned to H-knife (ClearCut^TM Knife H-type) or IT-knife (conventional IT knife) groups. Procedure times, therapeutic outcomes, and adverse events were analyzed. Results: A total of 98 patients (50 in the H-knife group and 48 in the IT-knife group) were analyzed. The median total procedure time was 11.9 minutes (range, 4.4-47.2 minutes) in the H-knife group and 12.7 minutes (range, 5.2-137.7 minutes) in the IT-knife group (P=0.209). Unlike the IT-knife group, which required additional devices in all cases, no additional devices were used in the H-knife group (P<0.001). En-bloc resection was performed for all lesions in both groups. The incidence of adverse events was not significantly different between groups (4.0% in the H-knife group vs. 8.3% in the IT-knife group; P=0.431). Conclusions: The newly developed hybrid device, the ClearCut^TM Knife H-type, had comparable efficacy to the conventional IT knife for gastric ESD.

• Journal of Yeungnam Medical Science
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• 제29권1호
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• pp.14-18
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• 2012

Background: The purpose of this study was to differentiate chromophobe renal cell carcinoma and clear cell renal cell carcinoma on helical CT. Methods: The CT images of 9 patients histopathologically proven to have chromophobe renal cell carcinoma and 20 patients with clear cell renal cell carcinoma were reviewed. The tumor sizes, margins, enhancement degrees and patterns, presence or absence of calcification, and tumor spread patterns (including perinephric changes, venous invasion, lymphadenopathy, and distant metastasis) were compared. Results: All the chromophobe renal cell carcinomas showed well-demarcated margins. Thechromophobe renal cell carcinomas showed milder enhancements than the clear cell renal cell carcinomas. The sensitivity and specificity for differentiating the chromophobe renal cell carcinoma from the clear cell renal cell carcinoma were 100 and 88%, respectively, when 101 Hounsfield units was used as the cut-off value in the corticomedullary phase, and 95 and 100% when a less-than-three-time enhancement change was used as a cut-off value in the corticomedullary phase (p<0.05). The chromophobe renal cell carcinomas (67%) tended to show a homogeneous enhancement whereas the clear cell renal cell carcinomas (85%) usually showed a heterogeneous enhancement (p<0.05). Statistical analysis revealed that the frequencies of the tumor spread pattern and calcification in the two subtypes didnot differ significantly (p>0.05). Conclusion: The CT findings of the chromophobe renal cell carcinomascompared to those of the clear cell renal cell carcinomas showed that there were mild enhancements in the corticomedullary phase, homogeneous enhancements, and well-demarcated margins.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.731-734
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• 2005

Cut slopes are collapsed in Korea every year. Cut slope collapses cause a loss of lives and assets. Many researchers make clear collapse factor of cut lope. Fresh rock weathered through reaction undergroundwater and groundwater. During weathering process, weathered minerals are created. Weathered minerals are analysed by X-ray diffraction meter. X-ray diffraction meter make possible quantity assessment of degree of weathering and indicator of potential collapse possibilities. This paper discuss possibilities of cut slope dangerous with analysis of weathered minerals of cut slope.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.518-522
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• 2011

Cartesian grid system has mainly been used in the casting simulation even though it does not nicely represent sloped and curved surfaces. These distorted boundaries cause several problems. A special treatment is necessary to clear these problems. A cut cell method on Cartesian grids has been developed to simulate three-dimensional mold filling Cut cells at a cast-mold interface are generated on Cartesian grids. Governing equations were computed using volume and areas of cast at cut cells. In this paper, we propose a new method that can consider the cutting cells which are cut by casting and mold based on the patial cell treatment (PCT). This method provides a better representation of geometry surface and will be used in the computation of velocities that are defined on the cell boundaries in the Cartesian gird system. Various test examples for several casting process were computed and validated. The analysis results of more accurate fluid flow pattern and less momentum loss owing to the stepped boundaries in the Cartesian grid system were confirmed. We can know the momentum energy at the cut cell is conserved by using the cut cell method. By using the cut cell method. performance of computation gets better because of reducing the whole number of meshes.

• 한국환경복원기술학회지
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• 제4권2호
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• pp.26-35
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• 2001

We are, now in the 21st century, that environmental preservation and the campaign for bio-diversity protection are very important issues the government must deal with as nation's main policy. To make road and building construction, housing land service, construction of golf fields, and various development works, we have made artificial topographical alterations and as a result, the cut-slop has been increased. However, without the proper study and clear planning, revegetation for the stability of the cut-slop has worked out. These efforts now are causing derangement of an ecosystem and spoiling the nature without considering for ecological adaptation. Therefore, we are going to find out the Revegetation Method to Cut-Slopes considering both the ecological adaptation and harmony with the nature.

• 한국정밀공학회지
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• 제14권3호
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• pp.21-27
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• 1997

This paper aims to clarify the effects of grinding conditions in form grinding of Sr-ferrite with the electro-plated diamond wheel. The main conclusions obtained were as follows. (1) The flexural strength and surface roughness of ferrite became the best at the peripheral wheel speed of 1700 m/min. (2) In the case of the depth of cut larger than 0.4mm, crack layers is induced in the ground surface, and the fracture type of chips exhibits slight ductile mode in the depth of cut smaller than 0.2mm. (3) Whe the depth of cut exceeds 0.6mm, the wheel life becomes extremely severe due to the large chipping and brack- age in the diamond grains. However, at the depth of cut .leq. 0.05mm, the diamond grain shows abrasive wear. (4) The decrease of flexural strength and the increase of surface roughness is in proportion to the increase of the feed rate. (5) Most effective nozzle setting angles with various delivery conditions of the grinding fluid, such as nozzle position .PHI. , flow rate Q, etc., were made clear.

• Journal of Ecology and Environment
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• 제41권10호
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• pp.290-301
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• 2017

Background: Forest edges create distinctive ecological space as adjacent constituents, which distinguish between different ecosystems or land use types. These edges are made by anthropogenic or natural disturbance and affects both abiotic and biotic factors gradually. This study was carried out to assess edge effects on disturbed landscape at the pine-dominated clear-cut area in a genetic resources reserve in Uljin-gun, eastern Korea. This study aims to estimate the distance of edge influence by analyzing changes of abiotic and biotic factors along the distance from forest edge. Further, we recommend forest management strategy for sustaining healthy forest landscapes by reducing effects of deforestation. Results: Distance of edge effect based on the abiotic factors varied from 8.2 to 33.0 m. The distances were the longest in $Mg^{2+}$ content and total nitrogen, $K^+$, $Ca^{2+}$ contents, canopy openness, light intensity, air humidity, $Na^+$ content, and soil temperature followed. The result based on biotic factors varied from 6.8 to 29.5 m, coverage of tree species in the herb layer showed the longest distance and coverage of shrub plant in the herb layer, evenness, species diversity, total coverage of herb layer, and species richness followed. As the result of calculation of edge effect by synthesizing 26 factors measured in this study, the effect was shown from 11.0 m of the forest interior to 22.4 m of the open space. In the result of stand ordination, Rhododendron mucronulatum, R. schlippenbachii, and Fraxinus sieboldiana dominated arrangement of forest interior sites and Quercus mongolica, Vitis amurensis, and Rubus crataegifolius dominated spatial distribution of the open area plots. Conclusions: Forest interior habitat lies within the influence of both abiotic and biotic edge effects. Therefore, we need a forest management strategy to sustain the stability of the plant and further animal communities that depend on its stable conditions. For protecting forest interior, we recommend selective logging as a harvesting method for minimizing edge effects by anthropogenic disturbance. In fact, it was known that selective logging contributes to control light availability and wind regime, which are key factors affecting microclimate. In addition, ecological restoration applying protective planting for the remaining forest in the clear-cut area could contribute to prevent continuous disturbance in forest interior.