• Journal of Ecology and Environment
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• v.33 no.2
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• pp.157-164
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• 2010

We evaluated the restoration effect by introducing willows as a means of controlling invasions of giant ragweed (Ambrosia trifida L.) on a riparian site. Our preliminary survey demonstrated that a problematic exotic species, giant ragweed and the representative riparian species, Salix koreensis are in competitive exclusive relationship. We planted willows at 1 m intervals on the bank of the Dongmun stream at Munsan, Paju, in Central Western Korea as an experimental restoration practice. We installed two 50 m $\times$ 5 m sized restored and non-restored for this experimental study. The non-restored plots were located on river banks, which were covered with concrete blocks and left in itself without any treatment. The height of willow was measured after each of three consecutive growing seasons and compared with the height of the giant ragweed. Although the height of Salix gracilistyla did not achieve the height of the giant ragweed, the height of S. koreensis surpassed that of giant ragweed in the third year after introduction. The results were also reflected in the relative light intensity on the herb layer of willow stand, and thereby the relative light intensities of stands, which were dominated by S. koreensis or restored by introducing S. koreensis, 1.99 $\pm$ 0.33 (%, mean $\pm$ SD) and 1.92 $\pm$ 0.50 (%, mean $\pm$ SD), respectively were lower than those in the stands treated by S. gracilistyla, 3.01 $\pm$ 0.43 (%, mean $\pm$ SD). The giant ragweed stands receive full sunlight as there are no any vegetation layers higher than the herb layer formed by the giant ragweed. As the result of Detrended Correspondence analysis ordination based on naturally established vegetation, the stands dominated by willows and giant ragweed showed different species composition between both stands. The species composition of the restoratively treated sites resembled the reference sites more than the non-treated sites. The species diversity (H') of the sites restored by introducing S. koreensis and S. gracilistyla was higher than the non-restored site dominated by A. trifida. On the basis of our results, the restoration of riparian vegetation equipped with integrated features could contribute not only to the control of exotic plants including giant ragweed but also to ensure the diversity and stability of riverine ecosystems.

• Journal of Korean Society on Water Environment
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• v.18 no.3
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• pp.327-336
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• 2002

Disinfection process in water treatment plants (WTPs) is one of the most important step in order to inactivate waterborne disease. However, what is the necessary disinfection in WTPs was not properly established in Korea. This study was conducted to evaluate disinfection performance in nationwide water treatment plants (n=474). Disinfection requirement based on the SWTR (Surface Water Treatment Rule) of the U.S. (1-log Giardia removal) was chosen in estimating the compliance. The scope of unit process for evaluating disinfection performance includes postdisinfection process in clearwells, pipeline, and storage tank. The worst water quality condition in individual WTPs was applied for the disinfection performance evaluation. The major results are as follows. First, it was appeared that 184 WTPs (39 %) provided insufficient disinfection performance. Disinfection performance was significantly improved during past 2 years. The ratio of the number of WTPs providing insufficient disinfection performance in 1999 and 2001 was 78 % and 41 %, respectively. One of major factors for this improvement was due to the improvement of $T_{10}/T$ value in clearwell, as a result of modification of clearwell facility. Second, if disinfection criteria is 3-log Giardia inactivation at worst water quality condition, then 19 % of all WTPs can not meet this disinfection criteria. And if disinfection criteria is strengthened to 4-log Giardia inactivation, then 58 % of all WTPs can not meet this disinfection criteria. Since disinfection criteria is decided by contamination level of Giardia in source water, it also needs the investigation of Giardia occurrence in source water.

• Journal of the Korean Institute of Landscape Architecture
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• v.34 no.1 s.114
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• pp.1-9
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• 2006

The purposes of this study are to develop the concept and the measurement method of IGS(Index of Greenness in Streetscape) and to analyze the present condition of street environments through field surveys of IGS in Seoul. IGS is a new index which directly expresses human's perceptions of plants in a street and defined as the area ratio of which leaves of plants occupy in an eye-level view of a person standing on the center line of a street. In practice, IGS can be calculated from a photograph taken from a center point of a street at about 1.5 meter height from the ground with single lens reflex camera equiped with 50mm standard lens. The photograph must have a special composition in a way that the center point of the photograph is positioning at the visual vanishing point of street center line. Then the IGS can be calculated by computing the percentage of the area covered with the plant leaves in the photograph. Types of streets in Seoul were classified according to road functions into 4 types. We performed field surveys and calculated IGSs from 300 sample sites in Seoul. Followings summarize some of study results. The average IGSs for arterial roads, highways, alleys and back streets are 16.91%, 16.33%, 13.97% and 7.50% respectively. The difference of average IGS values between Ginkgo biloba and Platanus occidentalis was relatively large. From observation IGSs from April 4th, 2003 to October 2nd, 2003, it was evident that the range and timing of each plant species' IGS change is not the same. According to questionnaire to public officials taking charge of street greening, the current evaluated IGS is 24.4%, and it is expected to be 40.7% in the future.

• The Plant Pathology Journal
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• v.23 no.1
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• pp.3-6
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• 2007

Chickpea wilt caused by Fusarium oxysporum f. sp. ciceris(FOC) is the most destructive disease in India. It is seed-borne as well as soil-borne pathogen. The role of seed-borne FOC in introducing and establishing wilt in FOC free soils is unknown. Using seeds of FOC infected chickpea cultivar K 850, we provided an evidence of establishing wilt disease in the FOC free soils within three crop cycles or seasons. In the first cycle, typical wilt symptoms were observed in 24 pots in 41 days after sowing. These 24 pots were used for second and third cycles without changing the soil. These 24 pots were sown with seeds collected from healthy plants of a susceptible cultivar JG 62, one seed per pot and development of wilt symptom was recorded. Wilt symptoms appeared in all the pots 26 days after sowing in second cycle and in 16 days after sowing in third cycle. On selective medium, all of the wilted plants yielded FOC in all the three cycles indicating that the mortality was due to wilt. FOC propagules on selective medium were 172, 1197, and 2280 $g^{-1}$ soil at the end of the first, second, and third cycles, respectively. These studies indicated that Fusarium wilt of chickpea is seed-borne and seeds harvested from wilted plants when mixed with healthy seeds can carry the wilt fungus to new areas and can establish the disease in the soil to economic threshold levels within three seasons.

• Korean Journal of Plant Resources
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• v.33 no.4
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• pp.404-416
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• 2020

Studies on the preservation and propagation of tropical and subtropical plants are required, but the studies are insufficient in Korea. Since 2013, the Tropical Plant Resources Research Center has been collaborating on field research and publication to preserve plant diversity in Myanmar protected areas and Sagging areas in cooperation with Ministry of Natural Resources and Environment Conservation and the Myanmar Forest Research Institute. This study is to provide information on cooperative projects. As a result of the joint research between the Korea National Arboretum and Myanmar, in December 2018, the Korea National Arboretum Tropical Plant Resources Research Center is on display for conservation and education purposes with the 65 Myanmar useful materials and specimens of 326 kinds of plants and specimens that Myanmar Forest Research Institute donated. This donation is the first case of Myanmar's export of plant organisms to a foreign country, and as for the Korea National Arboretum, it is the second official case of introducing a mass plant from foreign governments. The study will also accelerate preservation biodiversity and propagation methods of tropical and subtropical plants as well as research on biodiversity conservation and industrial use.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.233-240
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• 2000

Nuclear power plant structures may be exposed to aggressive environmental effects than may cause their strength and stiffness to decrease over their service lives, Although the physics of these damage mechanisms are reasonably well understood and quantitative evaluation of their effects on time-dependent structural behavior is possible in some instances such evaluations are generally very difficult and remain novel. The assessment of existing RC containment in nuclear power plants for continued service must provide quantitative evidence that they are able to withstand future extreme loads during a service period with an acceptable level of reliability. Rational methodologies to perform the reliability assessment can be developed from mechanistic models of structural deterioration using time-dependent structural reliability analysis to take earthquake loading uncertainties into account. The final goal of this study is to develop the reliability analysis of RC containment structures. The cause of the degrading is first clarified and the reliability assessment has been conducted. By introducing stochastic analysis based on random vibration theory the reliability analysis which can determine the failure probabilities has been established.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.87-90
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• 1996

Inherently safe plants are maintained through the systematic identification of potential hazards, and various hazard evaluation methods have been developed. Recently, much effort is given into the development of automated hazard evaluation system by introducing the expert system. An automated system will help to obtain consistency and to make the result more reliable. HAZOP study is one of the most systematic and logical evaluation procedure. However, it has disadvantages: experts should participate at the same time, the detailed study requires much man-hour, and the results depend on the expertise of the experts. Therefore, the automation of hazard evaluation is necessary to reduce the required time and to get the consistent evaluation results. In this study, HAxSYM, an expert system to automate HAZOP study, is developed. The case studies are performed to validate the effectiveness of the developed system, and the results are compared to the results of traditional method.

• Journal of the Korean Society of Tobacco Science
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• v.13 no.2
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• pp.34-41
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• 1991

To explore the possibility of introducing Zea mays transposable element Ac(activator) which can be used as a mutagen and gene tag in tobacco plants other than maitre, we tried to introduce a cloned Ac element into tobacco cells by an Agrobacterium tumefaciens binary vector system. Transformation of N. babacum cv. Burley 21 tissues and regeneration to whole plant were carried out. The frequency of the transformed callus induced in shoot induction media was higher than that of transformed callus induced in callus induction media. However, the calli were not grown in the second selection media, and became yellow senescent calli. Regenerated tobacco plantlets with foreign gene were also obtained in shoot induction media containing 100 $\mu\textrm{g}$/ml kanamycin and 100$\mu\textrm{g}$/ml carbenicillin. The leaf tissues of transformant was also resistant to 1000 $\mu\textrm{g}$/ml kanamycin. The chromosomal DNAs of transformant and normal plant of N. tabacum were digested by EcoR I and Hind III but not by Pst I.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.173-178
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• 1993

In this paper, we present an algorithmic technique for determining a feedback compensator which will stabilize the interval dynamic system, specifically, the robust regulator design for interval plants. The approach taken here is to allow the system parameters to live within prescribed intervals then design a dynamic feedback compensator which guarantees closed-loop system stable. The main contribution of this paper is the idea of introducing a "simplified Kharitonov's result" for low order polynomials to search for suitable compensator parameters in the compensator parameter space to make the uncertain syste robust. We also design the robust regulator which will D-stabilize (have the closed-loop poles in the left sector only) the dynamic interval system while having good performance. The nuerical examples are given to show the substantially improved robustness which results from our approach. approach.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.229-232
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• 1999

Nuclear power plant structures may be exposed to aggressive environmental effects that may cause their damage mechanisms are reasonably well understood and quantitative evaluation of their effects on time-dependent structural behavior is possible in some instances, such evaluations are generally very difficult and remain novel. The assessment of existing steel containment in nuclear power plants for continued service must provide quantitative evidence that they are able to withstand future extreme loads during a service period with an acceptable level of reliability. Rational methodologies to perform the reliability assessment can be developed from mechanistic models of structural deterioration, using time-dependent structural reliability analysis to take loading and strength uncertainties into account. The final goal of this study is to develop the analysis method for the analysis for the reliability of containment structures. The cause and mechanism of corrosion is first clarified and the reliability assessment method has been established. By introducing the equivalent normal distribution, the procedure of reliability analysis which can determine the failure probabilities has been established.