• Hwankyungkyoyuk
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• v.13 no.1
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• pp.44-52
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• 2000

In this study, the effects of structured controversy strategy, individual learning, and traditional learning on the learning of environmental unit in ‘General Science’ were compared. One hundred and forty-three 10th-graders had been taught about environmental issues-self purification, biological concentration, acid rain, greenhouse effect, noise, and radioactivity-for 6 class hours. Prior to the instructions, environmental attitudes test and self-esteem test were administered. After the instructions, their achievements, critical thinking, environmental attitudes. self-esteem, and views on Science-Technology-Society were examined. The results of 2-way ANCOVA and/or Kruskal-Wallis test revealed that there were no significant main effects in the scores of the achievement test and the critical thinking test. The environmental attitudes test scores tended to be highest in the structured controversy group, and lowest in the traditional learning group. Self-esteem scores of the structured controversy group and the individual learning group were higher than those of the traditional learning group. Significant differences by students' prior achievement level in students' critical thinking, environmental attitudes, and views on Science-Technology-Society were also found.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.2
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• pp.115-125
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• 2017

Fuel consumption in fisheries is a primary concern due to environmental effects and costs to fishermen. Much research has been carried out to reduce the fuel consumption related to fishing operations. The fuel consumption of fishing gear in fishing operation is generally related to hydrodynamic resistance on the gear. This research is to propose a low drag generated midwater trawl in terms of the gear design improvement using simulations. The results from the simulation were verified with results that mirrored the model experiments. From the results, the resistance force of the proposed gear decreased to 29% compared to that of the current gear. Furthermore, the gear performance also improved with increased gear mouth compared to the current one. Therefore, the proposed gear will be helpful to reduce the greenhouse gases from fishing operation. It will also contribute to the fishing industry by saving fuel.

• Journal of environmental and Sanitary engineering
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• v.15 no.1
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• pp.39-45
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• 2000

The purpose of this study was conducted to indentified the fixing quality of $CO_2$, the most important greenhouse effect gas, by microalgae Chlorella ellipsoidea in batch test apparatus. The glass flask of $1.4{\ell}$ culture media which was saturated with 99.99% pure $CO_2$ gas was setted water bath of $25^{\circ}C$, 5000Lux, and seeded 100$m\ell$ algae liquid. We checked the change of inorganic carbon concentration and algae population with time in culture media. The result were next: the growth of algae population relied on aquatic IC(inorganic carbon) concentration. And the pH was increased with decrease of IC concentration. The growth of algae population had positive correalation with $CO_2$ concentration, and the coefficient of correlation was 0.982. The specific growth rate($\mu$) of Chlorella ellipsoidea was 1.104/d, the maximum specific growth $rate({\mu}_{max}$) of 9.21/d, and helf velocity constant($K_s$) of $259mg/{\ell}$ by Monod equation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.6
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• pp.345-352
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• 2010

In this study, external condensation heat transfer coefficients(HTCs) of R134a and R1234yf are measured on a plain, low fin, and Turbo-C tubes at the saturated vapor temperature of $39^{\circ}C$ with the wall subcooling of $3{\sim}8^{\circ}C$. R1234yf is a new alternative refrigerant of low greenhouse warming potential for replacing R134a which is one of the greenhouse gases controlled by Kyoto protocol and is used extensively in mobile air-conditioners. Test results show that the external condensation HTCs of R1234yf are very similar to those of R134a for all three surfaces tested. For the application of condensation heat transfer correlations to the design of condensers charged with R1234yf, thorough property measurements are needed for R1234yf in the near future.

• Research in Plant Disease
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• v.8 no.1
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• pp.50-54
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• 2002

A total of 55 Colletotrichum isolates from strawberry plants with anthracnose symptoms(crown rot) were inhibited in mycelial growth on potato-dextrose agar(PDA) amended with fungicides in variable degrees depending on the chemicals used, especially showing no growth on PDA with 1 mg/m/tricyclazole. However, in the detached leaf test by treating chemicals before or after inoculation of Colletotrichum sp., tricyclazole was little effective in controlling symptom development; instead azoxystrobin, which had low in vitro inhibition of mycelial growth, inhibited strongly the symptom development. Some chemicals were tested for the control of strawberry crown rot in greenhouse using three methods, sprays soil drenching and plant dipping. No or little control effect were made by chemical spray and soil drenching, but plant dipping in chemical solution, especially azoxystrobin: reduced crown rot development by about 50% in the greenhouse suggesting that the azoxystrobin treatment may be an effective control method of the crown rot of strawberry. No differences in the control efficacy were noted according to the dipping time and chemical concentration of azoxystrobin not less than 10 min and 250 mg/m/, respectively.

• Research in Plant Disease
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• v.7 no.2
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• pp.69-79
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• 2001

Meloidogyne arenaria race 2 (59%) is widely distributed, followed by M. incognita race 1 (23%), and an unknown race of M. incognita (18 ％) in greenhouses in southern Korea. The key character to distinguish between M. arenaria and M. incognita is excretory pore in female head. When oriental melon, Cucumis melo L., grafted on Shintozoa (Cucurbit maxima x Cu. moschata) is transplanted in February in a plastic tunnel inside a greenhouse infested with M. arenaria, nematodes produced egg masses on roots at 40 days after transplanting and the soil juveniles (J2) population reach maximum in July to 3,817/100 ㎤. Juveniles are distributed relatively uniform over the 180-cm-wide row horizontally and the highest density occurs at 0-25 cm soil depth. For the control of root-knot nematodes, rice rotation, solarization, and soil addition treatments are the most effective (P=0.05); treatments reduce number of J2 over 90% and increase yield two times. Corn retation, fosthiazate, and soil drying treatment are moderately effective, while sesame and green onion rotations are not effective. The relationship between M. arenaria and yield of oriental melon is adequately described by a linear regression model. In the test with wild Cucumis genetic sources introduced from U.S.Dept. of Agriculture (USDA), one of C.heptadactylus, two of C.anguria, two of C. anguria var. longaculeatus, nine of C. metuliferus are resistant to both species of root-knot nematodes.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.5
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• pp.402-406
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• 2003

Greenhouse and laboratory studies were conducted to determine the allelopathic potentials of extracts or residues from sweet potato (Ipomoea batatas L. (Lam). The extracts applied on filter paper in a Petri dish bioassay significantly inhibited root growth of alfalfa. Aqueous leachates at 40g dry tissue $\textrm{L}^{-1}$ (g $\textrm{L}^{-1}$) from leaves showed the highest inhibition against alfalfa, and followed by stems and roots. Alfalfa root growth was significantly inhibited by methanol extracts of the same plants as the concentration increased. The effect of residue incorporation into soil on seedling growth of com, soybean, barnyard grass and eclipta was examined in the greenhouse, and results showed that the leaf residues at 200g $\textrm{kg}^{-1}$ by plant parts inhibited shoot dry and root dry weights of test plants by 60-80%. By means of HPLC, causative allelopathic substances present in plant parts of sweet potato "Sinyulmi" were identified as coumarin, trans-cinnamic acid, o-coumaric acid, p-coumaric acid, and chlorogenic acid. Total content of these compounds for leaves extracts were detected as the greatest amount in EtOAc fraction, especially trans-cinnamic acid was the greatest component. These results suggest that sweet potato plants have herbicidal potentials, and that their activities exhibit differently depending on plant parts.ant parts.

• Journal of Bio-Environment Control
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• v.25 no.3
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• pp.193-199
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• 2016

The research discussed experimental results on slip resistance force of rafter-purlin connection of plastic greenhouse and suggested a test method for evaluating slip resistance performance of the connection. Slip resistance forces were measured by four kinds of constraint conditions for specimens, for example, fixing or rolling the end of specimen. According to tests, it is noticed that constraint condition is able to significantly affect the slip resistance force. From a post-hoc comparison result, slip resistance force of test under fixing ends condition was larger than those under the other three constraint conditions. But the slip resistance force results in the fixing ends condition had greater measure of dispersion and three times of standard deviation than those from other constraint conditions. Based on the results obtained, effect of constraint condition for specimen on the slip test should be studied to enhance reliability of evaluation test of the slip resistance performance.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.111-111
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• 2003

Several fungal isolates were isolated from diseased monochoria(Monochoria vaginalis, weed of paddy field), which has an resistance to sulfonyl urea(S.U.) herbicide, and were evaluated in the laboratory and greenhouse as potential mycoherbicide. Eight fungi, Alternaria sp., Colletotrichum sp., Curvularia sp., Paenicillium sp and etc. were observed in the isolates. Pathogenicity testing were done on the monochorias in the greenhouse. Monochorias were inoculated with suspensions containing conidia of each isolate at the rates of 1.0 ${\times}$ 10$\^$5/ conidia/ml and 0.1％ Tween 80 with hand-gun sprayer. Curvularia sp. and an unidentified fungal isolate caused 90-95％ mortality on the monochorias 15∼20 days after inoculation. However the other isolates induced slight symptom of disease on the monochorias. In the early stage of disease development sun-burn appearance was shown at the infected site and the last infected leaves and stems were withered to death. Subsequently the pathogenicity on the rice was evaluated with above two effective isolates. From the test an unidentified isolate showed pathogenicity on the rice but Curvularia sp., named as DBB2003, didn't. Now the mass production and formulation using Curvularia sp. DBB2003 are in progress and the field test will be followed. Combination product with Curvularia sp. DBB2003 and chemical herbicide will be more effect to control the monochoria resisted on S.U. herbicide and need to be further tested.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.102-108
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• 2009

Fossil power plants firing lower grade coals or equipped with modified system for NOx controls are challenged with maintaining good combustion conditions while maximizing generation and minimizing emissions. In many cases significant derate, availability losses and increase in unburned carbon levels can be attributed to poor combustion conditions as a result of poorly controlled local fuel and air distribution within the boiler furnace. In order to develop a on-line combustion tuning system, field test was conducted at operating power boiler. During the field test the exhaust gases' $O_2$, NOx and CO was monitored by using a spatially distributed monitoring grid located in the boiler's high temperature vestibule and upper convective back-pass region. At these locations, the flue gas flow is still significantly stratified, and air in-leakage is minimal which enables tracing of poor combustion zones to specific burners and over-fire air ports. using these monitored information we can improving combustion at every point within the furnace, therefore the boiler can operate at reduced excess $O_2$ and gas temperature deviation, reduced furnace exit gas temperature levels while also reducing localized hot spots, corrosive gas conditions, slag or clinker formation and UBC. Benefits include improving efficiency, reducing NOx emissions, increasing output and maximizing availability. Discussion concerning the reduction of greenhouse gases is prevalent in the world. When taking a practical approach to addressing this problem, the best way and short-term solution to reduce greenhouse gases on coal-fired power plants is to improve efficiency. From this point of view the real time optimized combustion tuning approach is the most effective and implemented with minimal cost.