• The Korean Journal of Pesticide Science
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• v.7 no.3
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• pp.182-187
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• 2003

In order to elucidate a degradation characteristics of herbicide mefenacet in soil, the persistence in soils was studied under laboratory conditions for $90\sim120$ days at $28^{\circ}C$. Mefenacet residues were determined from the two soils which pre-treated by sterilization and flooding, respectively. Non-sterilized upland soil was used as a control. When 70 days elapsed from application time, $55\sim63%$ of mefenacet applied were dissipated in control soils. However, $32\sim33%$ of mefenacet applied were dissipated in the sterilized soils and $33\sim35%$ was dissipated in the flooded soils. 까 lese results indicated that the degradation of mefenacet was assumed to be due to microorganism, especially aerobic microbes. In order to elucidate the influence of water content on the persistence of mefenacet in soil, water content in soils was adjusted to 20, 50, and 80% of the water-holding capacity(Field capacity, WHC). The half-life of mefenacet in soil containing 20% and 50% of WHC were 82 and 73 days, respectively, after incubation for 90 days. However, the half-life in soil containing 80% of WHC was shortened to 61 days. These results indicated that degradation of mefenacet in soil was influenced by the activity of soil microorganism, organic matter content and water content.

• Journal of the Korean Institute of Landscape Architecture
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• v.34 no.1 s.114
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• pp.21-36
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• 2006

This study was undertaken to analyze the effects of pavement thermal properties and water retention characteristics on the surface temperature of the gray permeable cement concrete pavement during the summer. Following is a summary of major results. 1) The hourly surface temperature of pavement could be well predicted with a heat transfer model program that incorporated the input data of major meteorological variables including solar radiation, atmospheric temperature, dew point, wind velocity, cloudiness and the evaporation rate of the pavements predicted by the time domain reflectometry (TDR) method. 2) When the albedo was changed to 0.5 from an arbitrary starting condition of 0.3, holding other variables constant, the peak surface temperature of the pavement dropped by 11.5%. When heat capacity was changed to $2.5\;kJm^{-3}K^{-1}\;from\;1.5\;kJm^{-3}K^{-1}$, surface temperature dropped by 8.0%. When daily evaporation was changed to 1 mm from 2 mm, temperature dropped by 5.7%. When heat conductivity was changed to $2.5\;Wm^{-1}K^{-1}\;from\;1.5\;Wm^{-1}K^{-1}$, the peak surface temperature of the pavement fell by 1.2%. The peak pavement surface temperature under the arbitrary basic condition was $24.46^{\circ}C$ (12 a.m.). 3) It accordingly became evident that the pavement surface temperature can be most effectively lowered by using materials with a high albedo, a high heat capacity or a high evaporation at the pavement surface. The glare situation, however, is intensified by raising of the albedo, moreover if reflected light is absorbed into surrounding physical masses, it is changed into heat. It accordingly became evident that raising the heat capacity and the evaporative capacity may be the moot acceptable measures to improve the thermal characteristics of the pavement. 4) The sensitivity of the surface temperature to major meteorological variables was as follows. When the daily average temperature changed to $0^{\circ}C\;from\;15^{\circ}C$, holding all other variables constant, the peak surface temperature of the pavement decreased by 56.1 %. When the global solar radiation changed to $200\;Wm^{-2}\;from\;600\;Wm^{-2}$, the temperature of the pavement decreased by 23.4%. When the wind velocity changed to $8\;ms^{-1}\;from\;4\;ms^{-1}$, the temperature decreased by 1.4%. When the cloudiness level changed to 1.0 from 0.5, the peak surface temperature decreased by 0.7%. The peak pavement surface temperature under the arbitrary basic conditions was $24.46^{\circ}C$ (12 a.m.)

• Korean Journal of Poultry Science
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• v.29 no.2
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• pp.89-94
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• 2002

This study was performed to evaluate effects of different holding temperatures and storing periods during the pre-incubation period on egg hatchability of hens egg in broiler breeders. For the treatments 1(T1)~7(T7), which were stored fur 1(T1) to 7 days(T7) before egg incubation, respectively. There were three replicates per treatment and forty eggs per replicate. This study was performed twice, which were 40(Summer) and 50 weeks of age(Autumn) in broiler breeders. Storing ambient temperature of egg, egg weight, at 0 and 18 days during incubation, fertility, hatchability and embryo mortality were examined. Average hatchability was rapidly decreased only in Summer. Although it was not significantly different in Autumn. This experiment was concluded that storing periods of hatchery egg was influenced hatchability, especially in high ambient temperature conditions(Summer, above $25^{\circ}C$ ). In conclusion, we found out that optimum hatchability can be achieved with a storage temperature of 13 ~$19^{\circ}C$ for broiler breeder eggs stored for up to 7 days.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.362-367
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• 2023

Recently, research and development of proton exchange membrane fuel cells (PEMFC) membranes are progressing in the direction of thinning to reduce prices and improve performance. Demand for hydrogen-powered vehicles for commercial vehicles is also increasing, and their durability should be five times greater than those for passenger vehicles. Despite the thinning of the membranes, the durability of the membranes must be increased five times, so the improvement of the durability of the membranes has become more important. Since the acceleration durability evaluation time also needs to be shortened, the protocol using oxygen instead of air in the existing protocol was applied to a 10 ㎛ thin membrane to evaluate durability. The accelerated durability test (Open circuit voltage holding) was terminated at 720 hours. If the air-based department of energy (DOE) protocol was used, a lifespan of 450,000 km of driving hours would be expected, with a durability of about 1,500 hours. During the chemical durability evaluation, the active area of the electrode decreased by 51%, suggesting that catalyst degradation had an effect on membrane durability. Reducing the catalyst degradation rate is expected to increase membrane durability.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.6
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• pp.234-243
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• 2023

Zinc crystals of ZnO and SiO₂ in glaze raw materials, developed according to composition and firing requirements, are preferred because of their high decorative properties. However, most zinc crystal glazes have a high firing temperature and a narrow firing temperature range, making it difficult to use them as commercial glazes in ceramics. Therefore, in this study, it was expected that the firing temperature of a typical zinc crystal glaze could be lowered to below 1270℃ by using the eutectic effect through mixing frit, the main raw material used in manufacturing zinc crystal glaze. As a result, not only was the formation temperature of zinc crystals lower in the mixed frit glaze, but also the firing temperature range was widened to 1230~1270℃, making it possible to develop a glaze that produces crystals stably. The firing temperature was lowered to 1230~1250℃ and the holding temperature during cooling was lowered to about 950℃, resulting in the development of an economically effective glaze. When using a combination of frit, it has been shown that the holding temperature during cooling affects the recrystallization of zinc crystals depending on the composition of the glaze, and the crystal structure can be adjusted at this time. Additionally, the amount and shape of crystals can be controlled by using a nucleating agent.

• The Journal of Fisheries Business Administration
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• v.21 no.2
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• pp.55-84
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• 1990

The objective of this study is to develop an inventory model for the inventory management of a stocking point which sells processed fisheries products. The study, first of all, sets up fisheries processing companies, food companies, apparel companies, pharmaceutical companies and electronic and electrical companies as a population. Then, a comparative study is empirically applied to obtain the inventory characteristics of final products by industry through a survey of a sample selected by a random sampling procedure. The major inventory characteristics of processed fisheries products obtained from the above analysis can be summarized as follows : 1) The major demand characteristics of processed fisheries products is to have wide seasonal fluctuations because the supply of raw materials (i.e., fisheries products) heavily depends on the productive capacity of nature. 2) It has found that fisheries processing companies are the worst in inventory management among the various industries selected in the sample. However, the self-rating of inventory management system by inventory managers of companies shows that the fisheries processing companies are relatively higher than the other companies. 3) The portion of inventory holding cost out of inventory relevant cost is very high for processed fisheries products compared with final products of the other industries. 4) Processed fisheries products are distributed to final consumers through roughly two distribution echelons and take a parallel type inventory system for their distribution structure. In order to develop an inventory model which reflects the inventory characteristics of processed fisheries products mentioned in the above, an inventory model with partial backorders is developed under the situation of stochastic lead time under the consideration of the inventory characteristics of processed fisheries products and then an iterative solution method is provided for the model. Then this study analyzes sensitivity for the standard deviation of lead time in the model by numerical examples.

• Journal of the Korean Society for Heat Treatment
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• v.21 no.2
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• pp.94-100
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• 2008

The implant prototypes with various porosities were fabricated by Spark Plasma Sintering of atomized spherical titanium balls. The interface was observed by optical microscope. Sintering temperature and holding time were selected at the point of big change of Z-axis ratio during sintering. These experiments show that Spark Plasma Sintering of spherical titanium balls can be efficiently used to produce implants surfaced with titanium balls with various porosities in a short time less than 120 seconds by manipulating the current condition such as z-axis, temperature and balls size.

• Korean Journal of Food Science and Technology
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• v.26 no.6
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• pp.799-804
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• 1994

A 0.625% dispersion of the pretreated konjac (Amorphophallus konjac) flour was treated with 3 volumes of ethanol and the precipitate was dried at room temperature to produce purified glucomannan in 67.2% yield. Konjac glucomannan was analyzed for proximate composition and the contents of total dietary fiber and minerals. TLC analysis with a mobile phase of isopropanol : $H_2O$(4 : 1, v/v) revealed the presence of mannose and glucose as component sugars. The molecular mass of konjac glucomannan was in the range between 240 and 370 kDa as determined by HPLC with a Protein Pak 300SW column. Water holding capacity of konjac glucomannan was greater than those of most other gums except guar and xanthan gums. Konjac glucomannan accelerated foam formation of bovine serum albumin. As the concentration of konjac glucomannan increased up to 2%, maximum viscosity increased drastically, whereas the swelling time at maximum viscosity decreased. When swelling temperature increased, maximum viscosity and the swelling time at maximum viscosity decreased simultaneously.

• Journal of the Korean Vacuum Society
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• v.22 no.6
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• pp.277-284
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• 2013

Carbon coils could be synthesized using $C_2H_2/H_2$ as source gases and $SF_6$ as an incorporated additive gas under thermal chemical vapor deposition system. The Ni layer on the $SiO_2$ substrate was used as a catalyst for the formation of the carbon coils. The characteristics (formation densities, morphologies, and geometries) of the as-grown carbon coils on the substrate with or without the $H_2$ plasma pretreatment process were investigated. By the relatively short time (1 minute) $H_2$ plasma pretreatment on the Ni catalyst layered-substrate prior to the carbon coils synthesis reaction, the dominant formation of the carbon microcoils on the substrate could be achieved. After the relatively long time (30 minutes) $H_2$ plasma pretreatment process, on the other hand, we could obtain the noble-shaped geometrical nanostructures, namely the formation of the numerous carbon nanocoils along the growth of the carbon microcoils. This noble-shaped geometrical nanostructure seemed to play a promising role as the good catalyst support for holding the very tiny Ni catalyst grains.

• Korean Journal of Remote Sensing
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• v.30 no.4
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• pp.445-454
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• 2014

In recent days, trend technologies for cloud, bigdata, or mobile, as the important marketable keywords or paradigm in Information Communication Technology (ICT), are widely used and interrelated each other in the various types of platforms and web-based services. Especially, the combination of cloud and mobile is recognized as one of a profitable business models, holding benefits of their own. Despite these challenging aspects, there are a few application cases of this model dealing with geo-based data sets or imageries. Among many considering points for geo-based cloud application on mobile, this study focused on a performance test of mobile cloud of Bayesian image fusion algorithm with satellite images. Two kinds of cloud platform of Amazon and OpenStack were built for performance test by CPU time stamp. In fact, the scheme for performance test of mobile cloud is not established yet, so experiment conditions applied in this study are to check time stamp. As the result, it is revealed that performance in two platforms is almost same level. It is implied that open source mobile cloud services based on OpenStack are enough to apply further applications dealing with geo-based data sets.