• Journal of Food Hygiene and Safety
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• v.34 no.6
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• pp.583-590
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• 2019

As the consumption of fresh fruits and vegetables increases, food poisoning caused by foodborne pathogen contamination is not decreasing. To prevent the contamination of produce, a quick and easy, low-cost, environmentally-safe disinfection method that does not affect produce freshness or quality is needed. This study demonstrates a new-concept, circulating-water disinfection system that purifies water by using newly developed 'LED-PS (photosensitizer)-induced ROS generation unit'. Using various types of LED-PS induced ROS generation units, we investigated the conditions for reducing the density of various pathogenic bacteria by more than 3 log CFU / mL in 1 hour. The major operational factors affecting the density reduction of the LED-PS-induced ROS generation unit were analyzed. Depending on bacteria species, the density reduction rate was varied. The effect of the units on reducing the density of Bacillus cereus and Pectobacterium carotovorum subsp. carotovorum was high, but the effect on foodborne bacteria such as Escherichia coli was relatively low. In this circulating water disinfection system, the density reduction effect tended to increase as the flow rate increased and the initial bacterial density decreased. As the amount of PS absorbed beads increased, the density reduction effect increased exponentially in some bacteria. Model 3280, a double cylindrical unit connecting two single cylindrical units, could completely sterilize more than 3 log CFU/mL of B. cereus and P. carotovorum subsp. carotovorum in 30 minutes of LED irradiation.

• Journal of Bio-Environment Control
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• v.4 no.2
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• pp.181-187
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• 1995

This study was conducted to investigate the effect of NH$_4$H$_2$PO$_4$ on pH of the nutrient solution using municipal tap water during hydroponic culture of crisp lettuce (Lactuca sativa var. capitata) seedlings. The composition of starter solution was different from that of supplementary solution. The pH in the nutrient solution was suddenly declined and recovered as the supplementary solution was supplied. The pH of nutrient solution was increased with high temperature and, on the contrary, the EC of nutrient solution was decreased. It shows that plant absorbed nutrients more than water in given solution when the temperature and light was high. After supplying supplementary solution in 1st and End experiment, pH was slowly increased to 7 in NH$_4$H$_2$PO$_4$ 0.25me/$\ell$, but maintained 6.4-6.5 in NH$_4$H$_2$PO$_4$ 3me/$\ell$ and 6me/$\ell$. In 3rd experiment, pH was slowly increased from 6.7 to 7.4 in NH$_4$H$_2$PO$_4$ 0.25me/$\ell$, but decreased from 6-6.5 to 5-5.5 in NH$_4$H$_2$PO$_4$ 3me/$\ell$ and 6me/$\ell$. So it is suggested that the concentration between 0.25 me/$\ell$ and 3 me/$\ell$ by concentration base or the amount of NH$_4$H$_2$PO$_4$ between 1me/6 $\ell$ and 7me/6 $\ell$ by total quantity in solution is appropriate for stabilizing pH in the nutrient solution. Also this experiment suggests that hand operated measurements must be cautious due to the change of pH and EC within a 24-hour cycle.

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.491-497
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• 2011

In this work, we proposed the three different reactor systems for evaluating of synthetic natural gas(SNG) processes using the synthesis gas consisting of CO and $H_2$ and reactor systems to be considered are series adiabatic reaction system, series adiabatic reaction system with the recirculation and cooling wall type reaction system. The maximum temperature of the first adiabatic reactor in series adiabatic reaction system raised to 800. From the these results, carbon dioxide in product gas as compared to other systems was increased more than that expected due to water gas shift reaction(WGSR) and the maximum $CH_4$ concentration in SNG was 90.1%. In series adiabatic reaction system with the recirculation as a way to decrease the temperature in catalyst bed, the maximum $CH_4$ concentration in SNG was 96.3%. In cooling wall type reaction system, the reaction heat is absorbed by boiling water in the shell and the reaction temperature is controlled by controlling the amount of flow rate and pressure of feed water. The maximum $CH_4$ concentration in SNG for cooling wall type reaction system was 97.9%. The main advantage of the cooling wall type reaction system over adiabatic systems is that potentially it can be achieve almost complete methanation in one reactor.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.3
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• pp.232-241
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• 1984

For the purpose of investigating the effect of chemical composition of nitrogenous fertilizers such as urea, ammonium sulfate, ammonium phosphate(dibasic) and aqua-ammonia on growth, yield, efficiency and chemical properties of paddy soil this study was carried out at the same nitrogen concentration through field experiment. The results obtained was summarized as follows. 1. Nitrogenous fertilizers had an effect on plant height at heading stage, plant weight at harvest and No. of spikelet per panicle of rice plants in decreasing order: Ammonium sulfate > Diammonium phosphate > Urea > Ammonia water. But they didn't effect on culm length, spike length, dry matter weight, No. of grain per spike, ripening ratio and weight of 1000 grains of rice plants. 2. The absorbed amount of nitrogen and that of sulfur and nitrogen availability were highest in ammonium sulfate application and lowest in ammonia water application and these were positively correlated with yield. 3. The influence of nitrogenous fertilizers on nitrogen and sulfur efficiency and translocation efficiency was insignificant but that of ammonium sulfate on nitrogen efficiency was higher than that of the others. 4. The effect of nitrogenous fertilizers on a basic chemical properties of paddy soil experimented such as pH, C.E.C, exchangeable cation and organic matter was insignificant. But the sulfur content of ammonium sulfate application and phosphorous content of diammonium phosphate application were higher than that of the others.

• Journal of Bio-Environment Control
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• v.26 no.3
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• pp.227-234
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• 2017

This study aimed to investigate the nutrient solution developed by based on nutrient-water absorption rate of strawberry 'Maehyang' by comparing growth and yield for 8 months with 5 kinds of nutrient solution with different ion composition. Strawberry plants were planted at elevated bed and supplied with five kinds of nutrient solutions (RDA), Yamazaki, PBG, University of Seoul (UOS) and NewUOS from one month onwards. Five types of nutrient solution were supplied to the strawberry plants associated with EC $1.0dS{\cdot}m^{-1}$, pH 6.0, $150{\sim}300mL{\cdot}plant^{-1}$ per day. At 60 days after planting, leaf width and leaf petiole of the strawberry plants showed significant differences among nutrient solution types and photosynthesis was higher in RDA and NewUOS nutrient solution and lower in PBG nutrient solution. The EC of the drainage on vegetative growth stage was $0.7{\sim}0.8dS{\cdot}m^{-1}$, which is lower than the supplied EC level, and to $1.0-1.2dS{\cdot}m^{-1}$, afterwards. The pH of the drainage was higher in Yamzaki solution as 6.2~6.8, while the pH of the UOS nutrient solution was lower in 5.1~5.2. Nitrate content was most absorbed in vegetative growth stage and after flower clusters development. The potassium uptake was highest at the NewUOS followed by UOS and Yamazaki nutrient solution. At six months after -planting fresh weight and dry weight of shoot and root were higher in UOS and NewUOS nutrient solution than other nutrient solutions, and the dry matter ratio was lower at 43.5% in Yamazaki nutrient solution and 30.6% in NewUOS nutrient solution than other solutions. Length, width, weight, and sugar content of the strawberries harvested from December to February were unaffected by treatment, but yield was higher in NewUOS nutrient solution due to increasing fruit number and average weight. From March to May, number of fruit was higher in Yamazaki nutrient solution. In conclusion, there was no difference in the growth of 'Maehyang' when 5 nutrient solutions were grown under hydroponics. But in order to improve the marketability, the NewUOS nutrient solution is appropriate to use from planting to February and it is suitable to use Yamazaki nutrient solution after March when temperature is high and the amount of fruit set per inflorescence.

• Journal of the Daesoon Academy of Sciences
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• v.36
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• pp.1-34
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• 2020

It has been suggested that Jeungsan's prophetic poem that starts with the verse "For about seven or eight years, there will be a castle in the ancient country [七八年間古國城] ⋯" originally comes from Prophecies of Jeong Gam (鄭鑑錄). Despite Jeungsan, himself, obviously having been critical of that text, this claim has become the basic grounds for discourse suggesting that Jeungsan was not only interested in Prophecies of Jeong Gam but also considerably influenced by the text. However, the claim itself was formulated due to misunderstandings of the Chinese poems that had been included in A Compilation of Secret Prophecies Hidden in the Family-clan of Seogye (西溪家臧訣). These poems pursue a different ideological orientation than the poem from Prophecies of Jeong Gam. Ultimately, the Chinese poem in the verse 84 the chapter titled, Prophetic Elucidations in The Canonical Scripture of Daesoon Jinrihoe cannot provide a basis for the claim that Jeungsan was strongly influenced by Prophecies of Jeong Gam. This claim that Prophecies of Jeong Gam made a deep impact on Jeungsan and Daesoon Thought was based on three other texts outside of those that appear within verse 84 of Prophetic Elucidations. The first supposedly-related line is: "Heaven opens at the period of the Rat (Ja 子), Earth opens at the period of the Ox (Chuk 丑), humankind starts at the period of the Tiger (Ihn 寅)." This line comes from from Shao Kangjie's Book of Supreme World Ordering Principles (皇極經世), and the line could be quoted idiomatically as an expression in the Joseon Dynasty. Accordingly, attempts to relate Daesoon Thought to Prophecies of Jeong Gam are a distortion that arise from the assumption that Jeungsan had a significant interest in Prophecies of Jeong Gam. The second related line is "At the foot of Mount Mother (母岳山), a golden icon of Buddha has the ability to speak [母岳山下 金佛能言]." That line is nearly identical to the verse "On the summit of Mount Mother, a golden icon of Buddha has the ability to speak [母岳山頭 金佛能言]." Yet, Jeungsan changed '頭 (du, the summit)' to '下 (ha, the foot or under)' and express his own unique religious prophecy. This allusion to the prophecies of Jeong Gam is actually a criticism designed to disprove the earlier prophecy. Third, is the verse, "The form of Buddhism, creation of daoism, and propriety of Confucianism [佛之形體仙之造化儒之凡節]," which is characteristically related to Daesoon Thought. This verse can only be found in the prophetic text, Prophecies of Chochang (蕉蒼訣), and it is provided a main source when alleging that Prophecies of Jeong Gam was an influence on Daesoon Thought. However, considering the context of Prophecies of Chochang and the year of its publication (it is assumed to be compiled after 1950s), this does not hold water as Jeungsan had already passed into Heaven several decades before that time. This disqualifies the verse from being a basis for asserting Prophecies of Jeong Gam as an influence on Daesoon Thought. Contrary to the original assertion, there is a considerable amount of evidence that Prophecies of Chochang absorbed aspects of Daesoon Thought, which were simply revised in a novel way. There is no truly compelling evidence underpinning the argument that Prophecies of Jeong Gam had a unilateral impact on Daesoon Thought. There seems to be a great deal of confusion and numerous misinterpretations on this matter. Therefore, the claim that Daesoon Thought, as developed by Jeungsan, was influenced by the discourse on dynastic revolution and feng shui contained in Prophecies of Jeong Gam should be re-examined at the level of its very premise.