• Weed & Turfgrass Science
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• v.4 no.4
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• pp.360-367
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• 2015

This study was performed to determine the effects of silicon on zoysiagrass after the application of drought stress. The daily amount of water or scilicon solution was 150 ml per a pot. For 14 days, plants were treated with 0.1 and 1.0 mM silicon (Si) and with distilled water for control and the drought only-treatment. Afterward, the plants in Si and drought treatment were exposed to a 21-day under drought stress condition but the plants in control received water. The results indicated that the growth and the moisture and chlorophyll contents decreased in the drought only-treatment and 0.1 mM Si compared to the control. However, 1.0 mM Si showed an increase in the growth with a significant increase of water and chlorophyll contents. The MDA and $H_2O_2$ concentrations and electrolyte leakage decreased, while the radical scavenging capacity increased in 1.0 mM Si. 1.0 mM Si showed little to no differences in the growth and no differences in water and chlorophyll contents, electrolyte leakage, MDA and $H_2O_2$ concentrations and antioxidant capacity compared to the control. These results suggested that application of silicon is useful for drought tolerance improvement of zoysiagrass under drought that is occurring in turf fields.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.8
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• pp.109-118
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• 2010

It is expected that distribution system, interconnected with wind turbines, would experience the voltage problem due to WT's output. But most papers just consider this problem using the simulation or the theory only. In this paper, we verify this problem through the measurement at the distribution system and wind turbine. We explain the method for voltage management at distribution system. And we verify that the voltage of D/L interconnected with WTs could not be maintained properly using pole transformer's tap only. We consider some method to solve this problem and we propose the installation of SVR(step voltage regulator). Finally we show this method's validity through the simulation.

• Weed & Turfgrass Science
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• v.4 no.2
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• pp.111-117
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• 2015

The equilibrium moisture contents (EMC) in seeds of four Echinochloa (E. crus-galli var. crus-galli, E. crus-galli var, echinata, E. crus-galli var. praticola, E. esculenta) were measured at $20^{\circ}C$ with equilibration over a series of lithium chloride solutions with relative humidities ranging from 0.11 to 0.8 to determine sorption isotherms and safe storage relative humidity. Standard seed sorption isotherm models i.e. modified Henderson, modified Chung-Pfost, modified Halsey, modified Oswin and Guggenheim-Anderson-deBoer (GAB) equations were adopted to evaluate the goodness of fit to sorption isotherms. This study indicated that EMC of seeds was significantly different in four Echinochloa species at various relative humidity. The modified Oswin equations for E. crus-galli var. crou-galli, E. crus-galli var, echinata, E. esculenta and GAB equation for E. crus-galli var. praticola were adequate models for the EMC data. Seeds of four Echinochloa species have monolayer moisture contents when stored at RH < 0.1. These results show that seed moisture isotherm model should be selected according to genetic variation.

• Weed & Turfgrass Science
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• v.5 no.1
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• pp.35-41
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• 2016

Earthworm cast is a harmful factor which reduces the uniformity of management of turfgrass and play quality in golf courses and playground. This research was conducted to carry out the efficacy of some pesticide (bifenthrin GR + clothianidin GR, ethoprophos GR, imidacloprid SC, picoxystrobin WG, thiophanate-methyl WP) and tee tree (Camellia oliefera) extracts against reducing earthworm cast in golf courses. All tested materials were acted reducing earthworm cast, thiophanate-methyl among them showed the highest effect reducing earthworm casts in golf courses. Tea tree extracts was occurred similar efficacy among tested chemical pesticides. However, pellet type byproduct of tea seed extract and liquid formulation of tea tree extract were better than granule formulation of them. Byproduct of tea seed and tea tree extract can be used for alternative biological management material for reducing earthworm cast in heavily casting occurrence area.

• Weed & Turfgrass Science
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• v.5 no.1
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• pp.23-28
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• 2016

Zoysiagrass possessing the leaf yellowing with excessive tillers was first found in a golf course in Gyunggi province at last three to four years ago and since then have rapidly spread many golf courses in Korea. The symptom is very similar to that of yellow tuft or downy mildew, which is caused by Sclerophthora macrospora, on cool-season turfgrasses including Kentucky bluegrass and ryegrass. Microscopic study was firstly carried out to look over the presence of the pathogen in the infected leaf and stem tissues. Oospores and sporangia, reported as typical indicators of downy mildew, were obviously observed from the infected leaves. Using a set of primers based on the 18S ribosomal DNA from S. macrospora, the specific DNA fragment corresponding the gene was amplified. This study reveals that S. macrospora might be involved in spread of leaf yellowing of zoysiagrass with excessive tillers.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.7
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• pp.1299-1304
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• 2011

A wind turbine (WT) should be shut down as fast as possible to minimize its own damage in a storm-driven situation. Shutdown of a large wind farm requires a power grid to have a ramp-up capability large enough to balance between generation and consumption of electrical energy. This paper proposes a supervised shutdown algorithm of a wind farm to meet a required ramp-down rate in a grid code in the case of a storm-driven situation. The information on the speed and the direction of wind is measured at a wind mast (WM) installed around a wind farm. If the wind speed exceeds a cut-out speed, the number of WTs to be shut down simultaneously is decided to meet a required ramp-down rate of a grid-code. Arrival times to each WT from the WM are calculated and sorted in the order of time. Then a sequence of groups is generated. The shutdown start/end times of each group are decided to avoid superposition between adjacent two groups. The performance of the proposed shutdown algorithm is verified under various storm scenarios. Results indicate that the proposed algorithm can not only protect the wind farm in the case of a storm-driven situation but also meet the required ramp-down rate. In addition, the algorithm can produce more energy than that of a conventional shutdown algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1004-1011
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• 2006

In this study, we have performed a systematic case study on troubles and diagnoses of passenger car's engine based on OBD. We have acquired 1,242 data in order to analysis accurate troubles' causes and apposite diagnoses. 128 data of them are got using OBD apparatus, and the rest of them are collected on related website. As results, distribution on trouble cases shows bad idling(32%), poor acceleration(21%), stop in running(19%), faulty start(11%), inferior fuel economy(9%), and insufficient power(8%) in order of magnitude. And in the systematic cases, it is not difficult to detect troubles in a single part. But we know that special apparatus such as multichannel scanner is needed in complicated troubles. Furthermore we think that the survey is continued in various ways for more systematic case study on troubles and diagnoses.

• Weed & Turfgrass Science
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• v.1 no.4
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• pp.76-79
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• 2012

This study provides basic information on morphological characteristics of zoysia mite, Aceria zoysiae and symptom in zoysiagrass for turfgrass management in golf courses. Zoysiagrass mite distributed from Pocheon, Gyeonggii province to Jinju, Gyeongnam province and damaged turfgrasses from spring to fall. Damaged leaf by zoysiagrass mite was rolled unidirectionally and mite damaged leaves in the inside of rolled part. Leaves was turned to yellow and damaged area formed irregular yellow patch.

• Weed & Turfgrass Science
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• v.1 no.4
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• pp.50-56
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• 2012

The objectives of this research were to quantify resistance levels of transgenic rice expressing the bar gene to glutamine synthetase (GS)-inhibiting, and methionine sulfoximine and photosynthesis-inhibiting herbicide, paraquat, and compare the ammonium accumulation, chilling injury, and yield between transgenic and non-transgenic rice. The transgenic rice lines were 45-96-fold more resistant to glufosinate-ammonium than non-transgenic rice. The transgenic rice lines were also 18-fold more resistant to methionine sulfoximine, but was not resistant to paraquat, which has different target site. Glufosinate-ammonium increased the ammonium accumulation in leaves of non-transgenic rice plants, but had minimal or no effect on leaves of transgenic lines. The transgenic lines except for 258, 411, 607 and 608 were more susceptible during chilling and recovery than non-transgenic rice plants. The yield of transgenic lines 142, 144, 258 and 608 was similar or higher than that of non-transgenic rice in pot conditions.

• Weed & Turfgrass Science
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• v.3 no.3
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• pp.206-214
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• 2014

Numerous cases have been reported of naturalization by exotic ornamental plants. To obtain basic data about how those plants affect the ecosystems of Korea, we compiled a list of 78 species categorized as ornamentals from 309 naturalized species in Korea and analyzed their life forms, origin, and their current global status of naturalization and regulation. Plants belonging to Compositae comprised the largest group, with 23 species. In all, 75 species were considered herbaceous, and perennial species out-numbered annuals and biennials. Most species originated from Europe and North America. Except for Houttuynia cordata, the other 77 species were naturalized in other countries as well. Furthermore, 34 species, including Aster pilosus and Solidago altissima, have been subject to legal restrictions or classified as alert species in Korea or other countries. Therefore, monitoring may be required to prevent spread of those species, especially for species which have not been managed under domestic law up to now.