• Korean Journal of Environmental Biology
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• v.40 no.3
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• pp.281-289
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• 2022

The effect of five different constant temperatures (18, 21, 24, 27, and 30±1℃) and a photoperiod of 14 : 10 (L :D) h on the reproduction parameters of Spodoptera frugiperda was studied. The longevity of adult female S. frugiperda decreased with increasing temperature (22.4 days at 21℃ and 13.9 days at 30℃) but not at 18℃. The pre-oviposition period and oviposition period was the shortest at 30℃ compared to the other temperatures. The total fecundity egg count was 887.4, 1,246.4, 1,348.9, 1,154.9, and 1,034.2 at 18, 21, 24, 27 and 30℃, respectively, during its life span. The survival rate of female S. frugiperda decreased rapidly after 13 days at 18℃, after 14 days at 21℃, after 15 days at 27℃, and after 9 days at 24℃, and 30℃. On the third day after the start of oviposition, 50% of the total fecundity was accomplished. In corn fields at less than the 10-leaf stage, the distribution of S. frugiperda egg masses was observed in the middle and lower plant regions, corresponding to 46.8% and 41.4% of the total egg masses, respectively. Egg masses were mostly found on the underside of the leaf blade (abaxial) of corn(66.7%). After releasing S. frugiperda adults on May 12, May 17, May 25, and May 30, the number of eggs per egg mass was 89.9, 88.5, 126.6, and 127.9, respectively. Egg masses of the subsequent generations of S. frugiperda were observed from late June, and the number of eggs per egg mass was 155.8 in late June, 270.7 in early July, and 303.5 in mid-July.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.139-146
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• 2015

The amount of by-product from sulphur increases in domestic industrial facilities. However, the amount of its consumption is limited so that the amount of unused sulphur continues to increase. Therefore, in this study, the use sulfur polymer as the concrete surface protecting material was conducted. The compressive strength showed that as the substitution ratio of filler increased up to 40%, the compressive strength also increased. A high compressive strength was shown at the curing temperature of $40^{\circ}C$ (SS, FA) and $60^{\circ}C$ (OPC) according to the type of filler. The difference of compressive strength between air dry curing and water curing was insignificant so that there was no significant influence of moisture during curing process. The evaluation result of bond strength showed that the highest bond strength was shown at the air-dry condition of $40^{\circ}C$ regardless of type of filler. Bonding didn't occur properly during water curing in comparison to air dry curing. Also, in case of the specimen cured at $60^{\circ}C$, discoloration and hair cracks appeared due to the influence of temperature, and the highest bond strength was shown at the substitution ratio of 20% (SS, FA) and 30% (OPC) according to the type of filler. The releasing test result of harmful substance showed that no harmful substance was released, so there is no harmfulness in the surface protecting material using sulfur polymer. As a conclusion drawn in this study, it is most appropriate to substitute silica by approximately 20%, mix and cure at the air-dry condition of $40^{\circ}C$ in order to use sulfur polymer as the surface protecting material.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.4
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• pp.268-278
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• 2020

Flowering time has been put forward due to the recent abnormally warm winter, which often caused damages of flower buds by late frosts persistently. In the present study, cumulative chill unit and cumulative heat unit of Niitaka pear, which are required for releasing the endogenous dormancy and for flowering after breaking dormancy, respectively, were compared between flowering time prediction models used in South K orea. Observation weather data were collected at eight locations for the recent three years from 2018-2020. The dates of full bloom were also collected to determine the confidence level of models including DVR, mDVR and CD models. It was found that mDVR model tended to have smaller values (8.4%) of the coefficient of variation (cv) of chill units than any other models. The CD model tended to have a low value of cv (17.5%) for calculation of heat unit required to reach flowering after breaking dormancy. The mDVR model had the most accurate prediction of full bloom during the study period compared with the other models. The DVR model usually had poor skills in prediction of full bloom dates. In particular, the error of the DVR model was large especially in southern coastal areas (e.g., Ulju and Sacheon) where the temperature was warm. Our results indicated that the mDVR model had relatively consistent accuracy in prediction of full bloom dates over region and years of interest. When observation data for full bloom date are compiled for an extended period, the full bloom date can be predicted with greater accuracy improving the mDVR model further.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.85-92
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• 2005

The performance of a novel fermentation process, adopting a sludge blanket type configuration for higher hydrolysis/acidogenesis of the municipal primary sludge, was investigated under batch and semi-continuous conditions with various pH and temperature conditions. This acid elutriation slurry reactor provided higher system performance with a short HRT (5 days) and higher acidogenic effluent quality under pH 9 and thermophilic ($55^{\circ}C$) conditions. The hydrolysis of the sludge was revealed to be significantly dependent on seasonal effects for sludge characteristics but with little impact on acidogenesis. Based on the rainy season at the optimum conditions, VFA production and recovery fraction ($VFA_{COD}/COD$) were $0.18\;g\;VFA_{COD}\;g^{-1}\;VSS_{COD}$ and 63%. As byproducts, nitrogen and phosphorus releasing were $0.006\;g\;N\;g^{-1}\;VSS_{COD}$ and $0.003\;g\;P\;g^{-1}\;VSS_{COD}$, respectively. For the mass balance in a full-scale plant($Q=158,880\;m^3\;day^{-1}$) based on the rainy season, the VFA and non-VFA(as COD) production were $3,110\;kg\;VFA_{COD}\;day^{-1}$ and $1,800\;kg\;COD\;day^{-1}$, resulting in an increase of organics of $31\;mg\;COD\;L^{-1}$ and $20\;mg\;VFA_{COD}\;L^{-1}$ and nutrients of $0.7\;mg\;N\;L^{-1}$ and $0.3\;mg\;P\;L^{-1}$ in the influent sewage. The economical benefit from this process application was estimated to be about $67 per $1,000m^3$ of sewage except for energy requirements and also, better benefits can be expected during the dry season. Also, the results revealed that the process has various additional advantages such as pathogen-free stabilized solids production, excellent solids control and economical benefits.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.1
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• pp.1-7
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• 2009

This study has been focused on determining the chemical composition of $^{14}C$ - in terms of both organic and inorganic $^{14}C$ contents - in reactor coolant from 3 different PWR's reactor type. The purpose was to evaluate the characteristic of $^{14}C$ that can serve as a basis for reliable estimation of the environmental release at domestic PWR sites. $^{14}C$ is the most important nuclide in the inventory, since it contributes one of the main dose contributors in future release scenarios. The reason for this is its high mobility in the environment, biological availability and long half-life(5730yr). More recent studies - where a more detailed investigation of organic $^{14}C$ species believed to be formed in the coolant under reducing conditions have been made - show that the organic compounds not only are limited to hydrocarbons and CO. Possible organic compounds formed including formaldehyde, formic acid and acetic acid, etc. Under oxidizing conditions shows the oxidized carbon forms, possibly mainly carbon dioxide and bicarbonate forms. Measurements of organic and inorganic $^{14}C$ in various water systems were also performed. The $^{14}C$ inventory in the reactor water was found to be 3.1 GBq/kg in PWR of which less than 10% was in inorganic form. Generally, the $^{14}C$ activity in the water was divided equally between the gas- and water- phase. Even though organic $^{14}C$ compound shows that dominant species during the reactor operation, But during the releasing of $^{14}C$ from the plant stack, chemical forms of $^{14}C$ shows the different composition due to the operation conditions such as temperature, pH, volume control tank venting and shut down chemistry.

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.3
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• pp.103-134
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• 1977

The physiological and biochemical role of potassium for upland crops according to recent research reports and the nutritional status of potassium in Korea were reviewed. Since physical and chemical characteristics of potassium ion are different from those of sodium, potassium can not completely be replaced by sodium and replacement must be limited to minimum possible functional area. Specific roles of potassium seem to keep fine structure of biological membranes such as thylacoid membrane of chloroplast in the most efficient form and to be allosteric effector and conformation controller of various enzymes principally in carbohydrate and protein metabolism. Potassium is essential to improve the efficiency of phoro- and oxidative- phosphorylation and involve deeply in all energy required metabolisms especially synthesis of organic matter and their translocation. Potassium has many important, physiological functions such as maintenance of osmotic pressure and optimum hydration of cell colloids, consequently uptake and translocation of water resulting in higher water use efficiency and of better subcellular environment for various physiological and biochemical activities. Potassium affects uptake and translocation of mineral nutrients and quality of products. potassium itself in products may become a quality criteria due to potassium essentiality for human beings. Potassium uptake is greatly decreased by low temperature and controlled by unknown feed back mechanism of potassium in plants. Thus the luxury absorption should be reconsidered. Total potassium content of upland soil in Korea is about 3% but the exchangeable one is about 0.3 me/100g soil. All upland crops require much potassium probably due to freezing and cold weather and also due to wet damage and drought caused by uneven rainfall pattern. In barley, potassium should be high at just before freezing and just after thawing and move into grain from heading for higher yield. Use efficiency of potassium was 27% for barley and 58% in old uplands, 46% in newly opened hilly lands for soybean. Soybean plant showed potassium deficiency symptom in various fields especially in newly opened hilly lands. Potassium criteria for normal growth appear 2% $K_2O$ and 1.0 K/(Ca+Mg) (content ratio) at flower bud initiation stage for soybean. Potassium requirement in plant was high in carrot, egg plant, chinese cabbage, red pepper, raddish and tomato. Potassium content in leaves was significantly correlated with yield in chinese cabbage. Sweet potato. greatly absorbed potassium subsequently affected potassium nutrition of the following crop. In the case of potassium deficiency, root showed the greatest difference in potassium content from that of normal indicating that deficiency damages root first. Potatoes and corn showed much higher potassium content in comparison with calcium and magnesium. Forage crops from ranges showed relatively high potassium content which was significantly and positively correlated with nitrogen, phosphorus and calcium content. Percentage of orchards (apple, pear, peach, grape, and orange) insufficient in potassium ranged from 16 to 25. The leaves and soils from the good apple and pear orchards showed higher potassium content than those from the poor ones. Critical ratio of $K_2O/(CaO+MgO)$ in mulberry leaves to escape from winter death of branch tip was 0.95. In the multiple croping system, exchangeable potassium in soils after one crop was affected by the previous crops and potassium uptake seemed to be related with soil organic matter providing soil moisture and aeration. Thus, the long term and quantitative investigation of various forms of potassium including total one are needed in relation to soil, weather and croping system. Potassium uptake and efficiency may be increased by topdressing, deep placement, slow-releasing or granular fertilizer application with the consideration of rainfall pattern. In all researches for nutritional explanation including potassium of crop yield reasonable and practicable nutritional indices will most easily be obtained through multifactor analysis.