• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2A
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• pp.169-176
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• 2010

Generally, poly-urea is widely used as waterproof coating material due to its superior adhesiveness, elongation capacity, and permeability resistance. In addition, it can be quickly and easily applied on structure surfaces using spray application. Since it hardens in about 30 seconds after application, its construction efficiency is very high and its usage as a special functional material is also excellent. However, currently, poly-urea is mostly used as waterproof coating material and the researches on its usage as a retrofitting material is lacking at best. Therefore, basic studies on the use of poly-urea as a general structural retrofitting material are needed urgently. The objective of this study is to develop most optimum poly-urea composition for structure retrofitting purpose. Moreover, the structural strengthening capacity of the developed poly-urea is evaluated through flexural capacity experiments on RC beams and RC slabs. From the results of the flexural test of poly-urea strengthened RC beam and slab specimens, the poly-urea and concrete specimen showed monolithic behavior where ductility and ultimate strength of the poly-urea strengthened specimen showed slight increase. However, the doubly reinforced specimens with FRP sheet and poly-urea showed lower capacity than that of the specimen reinforced only with FRP sheet.

• Korean Journal of Hazardous Materials
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• v.2 no.1
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• pp.18-26
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• 2014

We analyzed the demand of competent authorities requiring adequate technical information for initial investigation of chemical accidents. Reflecting technical reports on chemical accident response by environmental agencies in the U.S. and Canada, we presented information on environmental diffusion and toxic effects available for the first chemical accident response. Hydrogen fluoride may have the risk potential to corrode metals and cause serious burns and eye damages. In case of inhalation or intake, it could have severe health effects. The substance itself is inflammable, but once heated, it decomposes producing corrosive and toxic fume. In case of contact with water, it can produce toxic, corrosive, flammable or explosive gases and its solution, a strong acid, may react fiercely with a base. In case of hydrogen fluoride leak, the preventive measures are to decrease steam generation in exposed sites, prevent the transfer of vapor cloud and promptly respond using inflammable substances including calcium carbonate, sodium bicarbonate, ground limestone, dried soil, dry sand, vermiculite, fly ash and powder cement. The method for fire fighting is to suppress fire with manless hose stanchions or monitor nozzles by wearing the whole body protective clothing equipped with over-pressure self-contained breathing apparatus from distance. In case of transport accident accompanied with fire, evacuation distance is 1,600m radius. In cae of fire, fire suppression needs to be performed using dry chemicals, CO₂, water spray, water fog, and alcohol-resistance foam, etc. The major symptoms by exposure route are dyspnoea, bronchitis, chemical pneumonia and pulmonary edema for respiration, skin laceration, dermatitis, burn, frostbite and erythema for eyes, and nausea, diarrhea, stomachache, and tissue destruction for digestive organs. In atmosphere, its persistency is low, and its bioaccumulation in aquatic organism is also low.

• Applied Chemistry for Engineering
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• v.35 no.3
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• pp.239-247
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• 2024

When a fire occurs on a naval vessel, rapid suppression and control are essential to mitigate potential human and material losses. Due to the nature of naval vessels, the risk of fuel fires is significant, making the use of aqueous film-forming foam (AFFF) crucial for effective fire suppression. Additionally, the possibility of fires occurring within compartments on the vessel must also be considered. Understanding the trajectory and application range of AFFF in such environments is vital, necessitating the design of firefighting systems tailored to compartmental conditions. In this study, an analysis was conducted to investigate the feasibility of applying spray height and angle for AFFF using computational fluid dynamics (CFD) methodology as a validation tool. Based on these findings, CFD analysis results applicable to compartment environments on naval vessels were obtained. These results will serve as the foundation for the development of firefighting systems capable of promptly responding to fuel fires within naval vessel compartments.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.244-248
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• 2013

This study was carried out to investigate the residual characteristics and calculate processing factor of the environment friendly material matrine in fresh chilli pepper by drying. Spray solution of matrine was prepared by dilution of the commercial product (2% active ingredient) with water at 1 : 1000 (v/v) ratio and sprayed onto chilli pepper plants at seven day intervals. Samples were collected at 0, 1, 3, 5 and 7 days after last application and then dried using a hot air dry oven at $60^{\circ}C$ for 36 hours until the water content was reduced to 14%. Recoveries and storage period stabilities of matrine in the samples ranged from 106.6 to 119.1% and 106.6 to 113.1%, respectively. The residual concentrations of matrine in fresh chilli pepper and dried chilli peppers treated only once were found to be from less than 0.01 to 0.11 and from 0.03 to 0.25 mg/kg, respectively. In case of plants sprayed twice with matrine, the residual concentrations ranged from 0.02 to 0.12 and from 0.04 to 0.4 mg/kg, respectively. Processing factor of matrine in the fresh chilli pepper by drying was found to be from 1.5 to 3.3, indicating that the residual concentration of matrine in dried chilli pepper increased about two or three times by drying.

• Horticultural Science & Technology
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• v.29 no.6
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• pp.555-560
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• 2011

The objective of this study was carried out to investigate the proper plant growth regulator for increasing the number of flower, fruit set, and to enlarge the size of the berries in Ardisia pusilla. Flower bud formation was used rooted cutting, and fruit set, enlargement, and coloration of fruit were used with two years-old. $GA_3$ concentrations were treated with 0, 100, 200, or $400mg{\cdot}L^{-1}$. Flower bud formation was effective in $400mg{\cdot}L^{-1}$ $GA_3$ and it was 1.8 times greater than control. Plant growth regulators were applied by foliar spray at full bloom stage to increase the fruit set. As a result, $GA_3$ was the most effective for increasing fruit set. Also, auxins of 4-CPA (Tomatotone, Donbu hitech Co., Korea) and dichloprop triethanol amine (Antifall, Bayer Crop Science Co., Ltd., Korea) were effective. When $GA_3$ concentrations of 0.5 and $1.0mg{\cdot}L^{-1}$ were used, fruit set (%) reached to 70% and 77%, respectively. Effectiveness of $GA_3$ was 1.8 times greater than control. Also, auxins, dichloprop triethanol amine increased to about 7-12% during fruit setting, but cytokinin and anti-gibberellin were ineffective. To investigate the fruit enlargement and coloration, $GA_3$ was treated with 0.3, 0.6, and $1.2mg{\cdot}L^{-1}$. Fruit enlargement was achieved to about 15% by $GA_3$ $0.6mg{\cdot}L^{-1}$ when $GA_3$ was treated 3 times at the interval of 1 month per treatment when fruit size was about 2-3mm (after full-blooming two months). But anthocyanin contents for coloration of fruit skin were not significant according to $GA_3$ concentration. The results showed that $GA_3$ enhanced bud formation, fruit set and enlargement of fruit size in Ardisia pusilla.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.11
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• pp.1615-1634
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• 2004

A review was undertaken to obtain information on the sustainability of pig free-range production systems including the management, performance and health of pigs in the system. Modern outdoor rearing systems requires simple portable and flexible housing with low cost fencing. Local pig breeds and outdoor-adapted breeds for certain environment are generally more suitable for free-range systems. Free-range farms should be located in a low rainfall area and paddocks should be relatively flat, with light topsoil overlying free-draining subsoil with the absence of sharp stones that can cause foot damage. Huts or shelters are crucial for protecting pigs from direct sun burn and heat stress, especially when shade from trees and other facilities is not available. Pigs commonly graze on strip pastures and are rotated between paddocks. The zones of thermal comfort for the sow and piglet differ markedly; between 12-22$^{\circ}C$ for the sow and 30-37$^{\circ}C$ for piglets. Offering wallows for free-range pigs meets their behavioural requirements, and also overcomes the effects of high ambient temperatures on feed intake. Pigs can increase their evaporative heat loss via an increase in the proportion of wet skin by using a wallow, or through water drips and spray. Mud from wallows can also coat the skin of pigs, preventing sunburn. Under grazing conditions, it is difficult to control the fibre intake of pigs although a high energy, low fibre diet can be used. In some countries outdoor sows are fitted with nose rings to prevent them from uprooting the grass. This reduces nutrient leaching of the land due to less rooting. In general, free-range pigs have a higher mortality compared to intensively housed pigs. Many factors can contribute to the death of the piglet including crushing, disease, heat stress and poor nutrition. With successful management, free-range pigs can have similar production to door pigs, although the growth rate of the litters is affected by season. Piglets grow quicker indoors during the cold season compared to outdoor systems. Pigs reared outdoors show calmer behaviour. Aggressive interactions during feeding are lower compared to indoor pigs while outdoor sows are more active than indoor sows. Outdoor pigs have a higher parasite burden, which increases the nutrient requirement for maintenance and reduces their feed utilization efficiency. Parasite infections in free-range pigs also risks the image of free-range pork as a clean and safe product. Diseases can be controlled to a certain degree by grazing management. Frequent rotation is required although most farmers are keeping their pigs for a longer period before rotating. The concept of using pasture species to minimise nematode infections in grazing pigs looks promising. Plants that can be grown locally and used as part of the normal feeding regime are most likely to be acceptable to farmers, particularly organic farmers. However, one of the key concerns from the public for free-range pig production system is the impact on the environment. In the past, the pigs were held in the same paddock at a high stocking rate, which resulted in damage to the vegetation, nutrient loading in the soil, nitrate leaching and gas emission. To avoid this, outdoor pigs should be integrated in the cropping pasture system, the stock should be mobile and stocking rate related to the amount of feed given to the animals.

• Research in Plant Disease
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• v.8 no.2
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• pp.84-91
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• 2002

Disease forecasting in Korea was first studied in the Department of Fundamental Research, in the Central Agricultural Technology Institute in Suwon in 1947, where the dispersal of air-borne conidia of blast and brown spot pathogens in rice was examined. Disease forecasting system in Korea is operated based on information obtained from 200 main forecasting plots scattered around country (rice 150, economic crops 50) and 1,403 supplementary observational plots (rice 1,050, others 353) maintained by Korean government. Total number of target crops and diseases in both forecasting plots amount to 30 crops and 104 diseases. Disease development in the forecasting plots is examined by two extension agents specialized in disease forecasting, working in the national Agricul-tural Technology Service Center(ATSC) founded in each city and prefecture. The data obtained by the extension agents are transferred to a central organization, Rural Development Administration (RDA) through an internet-web system for analysis in a nation-wide forecasting program, and forwarded far the Central Forecasting Council consisted of 12 members from administration, university, research institution, meteorology station, and mass media to discuss present situation of disease development and subsequent progress. The council issues a forecasting information message, as a result of analysis, that is announced in public via mass media to 245 agencies including ATSC, who informs to local administration, the related agencies and farmers for implementation of disease control activity. However, in future successful performance of plant disease forecasting system is thought to be securing of excellent extension agents specialized in disease forecasting, elevation of their forecasting ability through continuous trainings, and furnishing of prominent forecasting equipments. Researches in plant disease forecasting in Korea have been concentrated on rice blast, where much information is available, but are substan-tially limited in other diseases. Most of the forecasting researches failed to achieve the continuity of researches on specialized topic, ignoring steady improvement towards practical use. Since disease forecasting loses its value without practicality, more efforts are needed to improve the practicality of the forecasting method in both spatial and temporal aspects. Since significance of disease forecasting is directly related to economic profit, further fore-casting researches should be planned and propelled in relation to fungicide spray scheduling or decision-making of control activities.

• The Korean Journal of Pesticide Science
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• v.19 no.3
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• pp.255-263
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• 2015

Promoting the organic farming, much of the plant extracts used for controlling pests and fungi have been imported from China, India and Myanmar. But, it is so worrisome that aquatic animals such as muddy loach inhabiting in paddy field and common carps in river exposed to the pests and fungi likely be harmed. This study was conducted in order to evaluate the risks of aquatic animals influenced by the three plant extracts, i.e. Sophora flavescens, Azadirachta indica and Derris elliptica. The toxicities of common carp (Cyprinus Carpio), muddy loach (Misgurnus anguillicaudatus) and PEC (Predicted environmental concentration) exposed to the three plant extracts were estimated by the typical spray volume method. Risks were determined by the toxicity value as 48-hr $LC_{50}$ (Lethal concentration, median) or NOEC (No observed effect concentration) into PEC. 48-hr $LC_{50}$ of Common carp and NOEC by Sophora flavescens extracts was 7.9 and 6.2 mg/L, 26.8 and 21.8 mg/L by Azadirachta indica extracts and 47.0 and < 24.0 mg/L by Derris elliptica extracts, respectively. 48-hr $LC_{50}$ of Muddy loach and NOEC by Sophora flavescens extracts was 16.9 and 10.0 mg/L, 35.6 and 30.0 mg/L by Azadirachta indica extracts, and 73.9 and < 40 mg/L by Derris elliptica extracts, respectively. Therefore, acute toxicities of the three plant extracts for aquatic animals were proved to be very low level. PEC of Sophora flavescens extracts in paddy, drainage and river water was 68.0~3.0, 11.33~0.50 and 3.0~0.0018 mg/L, respectively. TER of Sophora flavescens extracts in the three water was 0.2~5.6, 1.5~33.8 and 2.6~4388.9, respectively. PEC of Azadirachta indica extracts in paddy, drainage and river water was 90.9~1.2, 15.2~0.2 and 4.8~0.00075 mg/L, respectively. TER of Azadirachta indica extracts in the three water was 0.4~29.7, 2.3~178.0 and 4.5~35733.3, respectively. PEC of Derris elliptica extracts in river water was 0.0063 mg/L. TER of Derris elliptica extracts in river water was 5222~15667.

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.413-420
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• 2013

The purpose of this study was to evaluate the control efficacy of major environment-friendly control agents against powdery mildew, as affected by the application condition such as disease-developing stage and microclimate, as compared with the efficacy of pesticides in plug seedling of three Cucurbitaceae vegetables, including cucumber, melon, and oriental melon. Single or combined application of major six environment-friendly control agents was used in the experiment: two biofungicide (Ampelomyces quisqualis 94013 and Bacillus subtilis Y1336), two plant extracts (neem oil and extracts of Rheum undulatum), and two mineral materials (wettable sulfur powder and lime bordeaux mixture). These control agents were treated to the plug seedlings for preventing powdery mildew and curative applications for managing powdery mildew. In all treatments, the disease incidence declined as daily average temperatures increased to $30^{\circ}C$ for consecutive 6~8 days with maximum temperature over $40^{\circ}C$. In preventative application, the control efficacy against powdery mildew was the highest in the treatment of wettable sulfur powder, and lowest in the B. subtilis Y1336, with values of 20~40%. In cucumber seedlings, the preventive single application of neem oil or wettable sulfur powder was more effective than curative application of fungicides, while the control efficacy of these agents was similar to those of fungicides in melon seedlings. The single application of R. undulatum extracts was also effective in preventing the disease for both cucumber and melon seedlings, showing a higher control efficacy than those of biofungicides during seedling stage. The treatment of water spray was not effective and showed a higher disease incidence than the untreated control plot in the oriental melon and melon seedlings. The curative application with environment friendly control agents, after powdery mildew was first detected, could not successfully controlled the disease at the middle stage (5~10% of disease incidence) of disease development. The curative combined application of [R. undulatum extracts (1st application) + wettable sulfur powder (2nd) + neem oil (3rd)] showed the highest control efficacy among the other treatments, with control value over 80% at the early stage (less than 1% of disease incidence) of disease development.

• Horticultural Science & Technology
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• v.35 no.2
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• pp.210-219
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• 2017

This study was conducted to establish an efficient screening method for radish (Raphanus sativus) cultivars that are resistant to black spot, which is caused by Alternaria brassicicola. Seven A. brassicicola isolates were selected and investigated for their ability to produce spores and pathogenicity. Of these isolates, A. brassicicola KACC 40036 and 43923 produced abundant spores in V-8 juice agar medium and showed pathogenicity and strong virulence on radish seedlings. We examined the resistance of 61 commercial cultivars of radish to A. brassicicola KACC40036, and found that there are no highly resistant radish cultivars; however, some cultivars, such as 'Geumbong' and 'Searom', showed weak resistance to A. brassicicola. For further study, we selected four radish cultivars that showed different disease responses to A. brassicicola KACC40036. According to the growth stage of the radish seedlings, inoculum concentration, and incubation temperature of radish, development of black spot on four cultivars has been investigated. The results showed that younger seedlings were more sensitive to A. brassicicola than older seedlings, and the disease severity depended on the concentration of the spore suspension. The disease severity of plants incubated in humidity chamber at $25^{\circ}C$ was greater than that of plants grown at $20^{\circ}C$ or $30^{\circ}C$. Taken together, we suggest the following method for screening for radish plants that are resistant to A. brassicicola: 1) inoculate 16-day-old radish seedlings with an A. brassicicola spore suspension ($2.0{\times}10^5spores{\cdot}mL^{-1}$) using the spray method, 2) incubate the inoculated plants in a humidity chamber at $25^{\circ}C$ for 24 h and then transfer the plants to a growth chamber at $25^{\circ}C$ with 80% relative humidity under a 12 h light/dark cycle, and 3) assess the disease severity of the plants two days after inoculation.