• The Korean Journal of Pesticide Science
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• v.11 no.2
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• pp.67-71
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• 2007

Nobel series of 5-benzyloxymethyl-3-(thiophen-5-yl)-1,2-isoxazoline derivatives were designed and synthesized. The herbicidal activities of these compounds to main dominant weeds to these compounds were evaluated in pot tests that simulated rice paddy conditions. Most of the compounds showed high herbicidal activity to main dominant weeds occurring in rice field without the serious rice injury.

• Korean Journal of Environment and Ecology
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• v.4 no.1
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• pp.44-50
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• 1990

To investigate edge vegetation structure in the Mt. Sokri National Park, field survey was executed in August. 1990 and the result are as follows. Dominant edge species by crown-layer and smilarity of species composition seemed to be affected by existing upper layer vegetation, altitude aspect and physiographical location. and the edge vegetation at summit was severely different with one of the other environmental types. Species diversity of edge vegetation was highest at Northern midslope, lowest at Southern mid-slope. and Acer pseudo-sieboldiamun var. koreanum was appeared as a dominant species at all environmental types. Frequency classes of edge species were different by altitude, aspect, physiographicallocation. Acer pseudo-sieboldiamun var, koreanum, Quercus mongolica, Fraxinus rhynchophylla, Lespedeza maximowiczii, Weigela subsessilis showed high frequency class at all environmental condition.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.363-363
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• 2010

The high capillarity of a plastic fiber network having superhydrophilic Si-DLC coating is studied. Although the superhydrophilic surface maximize wetting ability on the flat surface, there remains a requirement for the more wettable surface for various applications such as air-filters or liquid-filters. In this research, the PET non-woven fabric surface was realized by superhydrophilic coating. PTE non-woven fabric network was chosen due to its micro-pore structure, cheap price, and productivity. Superhydrophobic fiber network was prepared with a coating of oxgyen plasma treated Si-DLC films using plasma-enhanced chemical vapor deposition (PECVD). We first fabricated superhydrophilic fabric structure by using a polyethylene terephthalate (PET) non-woven fabric (NWF) coated with a nanostructured films of the Si-incorporated diamond-like carbon (Si-DLC) followed by the plasma dry etching with oxygen. The Si-DLC with oxygen plasma etching becomes a superhydrophilic and the Si-DLC coating have several advantages of easy coating procedure at room temperature, strong mechanical performance, and long-lasting property in superhydrophilicity. It was found that the superhydrophobic fiber network shows better wicking ability through micro-pores and enables water to have much faster spreading speed than merely superhydrophilic surface. Here, capillarity on superhydrophilic fabric structure is investigated from the spreading pattern of water flowing on the vertical surface in a gravitational field. As water flows on vertical flat solid surface always fall down in gravitational direction (i.e. gravity dominant flow), while water flows on vertical superhydrophilic fabric surface showed the capillary dominant spreading.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.2
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• pp.155-163
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• 2020

Indoor airborne particles are consisted of outdoor- and indoor-generated particles, which can be characterized by their compositions, generation features and toxicity. The identification of source contribution of indoor and outdoor origin to indoor particles is important to understand PM_2.5 transport in a building as well as its impact on occupant health. The objective of this study is to investigate seasonal source contribution to indoor PM_2.5 concentration depending on airtightness of apartment units. To evaluate the source contribution, particle transport including penetration, generation, exfiltration in an apartment housing unit was simulated by using CONTAM with particle and airflow simulation parameters obtained from field measurements. The result showed that the outdoor source contribution to indoor air was relatively dominant in the leaky housing unit during spring (77.2%) and winter (73.9%), and the indoor source was dominant in the airtight housing unit during summer (60.3%) and fall (60.7%). These results indicate the seasonal health risk of indoor PM_2.5 can be varied according to airtightness of apartment units.

• Journal of The Korean Astronomical Society
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• v.55 no.3
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• pp.67-74
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• 2022

In this study, we perform a statistical investigation of the kinematic classification of 4,264 coronal mass ejections (CMEs) from 1996 to 2015 observed by SOHO/LASCO C3. Using the constant acceleration model, we classify these CMEs into three groups: deceleration, constant velocity, and acceleration motion. For this, we devise three different classification methods using fractional speed variation, height contribution, and visual inspection. The main results of this study can be summarized as follows. First, the fractions of three groups depend on the method used. Second, about half of the events belong to the groups of acceleration and deceleration. Third, the fractions of three motion groups as a function of CME speed are consistent with one another. Fourth, the fraction of acceleration motion decreases as CME speed increases, while the fractions of other motions increase with speed. In addition, the acceleration motions are dominant in low speed CMEs whereas the constant velocity motions are dominant in high speed CMEs.

• Journal of Environmental Science International
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• v.32 no.5
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• pp.329-341
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• 2023

We surveyed the vegetation of an ecological landscape preservation area (legally protected conservation areas or national parks) and the surrounding areas of Mt. Cheonggye, Republic of Korea, to explore the conservation implications for preservation areas and surrounding transition areas. We calculated diversity indices to identify the properties of the preservation and surrounding areas that are relevant to conservation efforts. We then compared the plant community composition between the areas using field and quadrat surveys in the preservation and surrounding areas. The cover of the dominant species in all tree and herb layers was markedly higher in the preservation area than in the peripheral zones. The species richness indices were significantly higher in the preservation area than in the peripheral zones. Ordination using detrended canonical correspondence analyses showed that the cover of the dominant tree species and rocks could explain the distribution of plant species in the Cartesian space of the ordination. Our results demonstrate that physiognomically designated protected areas match well with ecological data based on diversity indices and ordination analyses and that disturbances in the areas surrounding the ecological landscape of preservation areas can have considerable impacts on plant diversity indices. Hence, the preservation and management of surrounding areas are essential conservation elements for protecting the entire ecological landscape of preservation areas.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.3
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• pp.278-291
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• 2024

This study performed three research methods (destructive, non-destructive, and panoramic image analysis) to determine the most useful for identifying seaweed habitat characteristics. Panoramic images are suitable for understanding the overall seaweed distribution. The composition of the main dominant seaweed species showed a significant difference between the destructive and non-destructive methods using Quadrat. The destructive method showed Rhodophyta dominance, whereas the non-destructive was showed Phaeophyta as dominant. Destructive methods are disadvantageous because they destroy natural communities in sea areas where bleaching is severe. Non-destructive methods are disadvantageous because of the difficulty in analyzing small species. Performing 10 surveys using a non-destructive method was found to explain up to 80% of the species identified by the destructive method. However, considering the difficulty of field investigation, repeating the investigation with non-destructive methods at least 6-7 times is necessary to ensure that more than 60% of the destructive methods can be interpreted. To understand the distribution of oceanic marine algae, performing both destructive and non-destructive surveys are necessary, as each has its own merits and demerits.

• Weed & Turfgrass Science
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• v.3 no.2
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• pp.86-94
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• 2014

Survey was carried out in paddy fields to investigate the dominance of weed species and weed occurrence on 200 fields of southern Gyeonggi region in Korea during the year 2013. We observed 3 species of grass, 5 species of sedge, and 11 species of broadleaf and other weeds. The most dominant weed species was Eleocharis kuroguwai, followed by Echinochloa crus-galli, Sagittaria trifolia, Monochoria vaginalis, Scirpus juncoides and Bidens tripartita. The dominance value of E. kuroguwai and B. tripartita decreased compared to the survey results performed in 2005 but that of M. vaginalis, S. juncoides, S. trifolia and E. crus-galli increased. Weed occurrence increased from 2.83 g in 2005 to 3.51 g in 2013 based on weed dry weight per $m^2$. Occurrence ratio of annual weeds to perennial weeds changed from 45.2% : 54.8% in 2005 to 45.8% : 54.2% in 2013. If we analyze dominance of weed species based on the rice transplanting timing, E. kuroguwai and E. crus-galli were the most dominant weed species at mid-May transplanting, and M. vaginalis and S. juncoides were the most dominant weed species at late- May transplanting, and M. vaginalis and E. kuroguwai were the most dominant weed species at early-June transplanting. Since paddy weeds resistant to sulfonylurea herbicides are expected to be continuously increased, the regular monitoring of their occurrence and efficient control methods should be considered in future.

• Journal of KSNVE
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• v.7 no.3
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• pp.477-488
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• 1997

In order to control vibration in structures, it is desirable to be able to identify dominant paths of vibration transmission from sources through the structure to some points of interest. Structural intensity vector(power flow per width of cross section) using cross spectra is able to measure the vibration power flow at a point in a structure. This paper describes the structural intensity measurement of 2-dimensional structure. Structural intensity of 2-dimensional structure can be obtained from eight point cross spectral measurement per axis, or two point measurement per axis on the assumption of far field. Approximate formulation of the relation between bending waves in structures and structural intensity makes it possible to separate the wave components by which one can get a state of the vibration field. Experimental results are obtained on an infinite plate at the near and far field in flexural vibration. The measurement error of two point measurement is rather bigger than eight point measurement on account of the assumption that Poisson's ratio is 1. The structural intensity vectors on the plate are checked the ability to identify the path of vibration power flow in random excitation and 200Hz sine excitation, the result of two point measurememt is almost the same as the result of eight point measurement in 200Hz sine excitation.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.1 s.16
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• pp.63-68
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• 2005

LSIV (Large Scale Image Velocimetry), a technique of image analysis on velocity measurement, was applied to a hydraulic model experiment of river confluence. The surface velocities measured by using LSIV showed similar results with the mean velocities by using a traditional velocimeter, While a general velocimeter can measure only local point velocity, LSIV can measure whole velocity field with one shot. When it is applied to river confluence or around a bridge pier where local flow is dominant, LSIV may be a powerful tool to measure velocity field.