• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.3
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• pp.153-161
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• 2023

The worldwide effects of COVID-19 have led to a surge in online shopping and contactless services. The consumption pattern has caused the issues such as the environmental pollution together with the increase of plastic waste. Reducing the reliance on the petroleum based plastic use for the package and replacing it with environmentally friendly material are the simple ways in order to solve those problems. Paper is an eco-friendly product with high recyclability as the food packaging materials but has still poor barrier properties. A barrier coating on surface of the paper can be achieved with the proper packaging materials featuring water, gas and grease barrier. Polyethylene (PE) or polypropylene (PP) coatings which are generally laminated or coated to paper are widely used in food packaging applications to protect products from moisture and provide water or grease resistance. However, recycling of packaging containing PE or PP matrix is limited and costly because those films are difficult to degrade in the environment. This study investigated the recyclability of modified acrylic emulsion coating papers compared to PE and PP polymer matrixes as well as their mechanical and gas barrier properties. The results showed that PE or modified acrylic emulsion coated papers had better mechanical properties compared to the uncoated paper as a control. PE or PP coating papers showed strong oil resistance property, achieving a kit rating of 12. Those papers also had a significantly higher percentage of screen reject during the recycling process than modified acrylic coated paper which had a screen rejection rate of 6.25%. In addition an uncoated paper had similar value of a screen rejection rate. It may suggest that modified acrylic emulsion coating paper can be more easily recycled than PE or PP coating papers. The overall results of the study found that modified acrylic emulsion coating paper would be a viable alternative to suggest a possible solution to an environmental problem as well as enhancing the weak mechanical and poor gas barrier properties of the paper against moisture.

• Journal of Biosystems Engineering
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• v.5 no.1
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• pp.1-14
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• 1980

Threshing operation may be one of the most important processes in the paddy post-production system as far as the grain loss and labor requirement are concerned . head-feeding type threshers commercially available now in Korea originally were developed for threshing dry paddy in the range of 15 to 17 % in wet basis. However, threshing wet-paddy with the grain moisture content above 20 % has been strongly recommended, especially for new high-yielding Indica -type varieties ; (1) to reduce high grain loss incurred due to the handling operations, and (2) to prevent the quantitative and qualitative loss of milled -rice when unthreshed grains are rewetted due to the rainfall. The objective of this study were to investigate the adaptability of both a head-feeding type thresher and a throw-in type thresher to wet-paddy , and to find out the possiblilities of improving the components of these threshers threshing. Four varieties, Suweon 264 and Milyang 24 as Tongil sister line varieties, minehikari and Jinhueng as Japonica-type varieties, were used at the different levels of the moisture content of grains. Both the feed rate and the cylinder speed were varied for each material and each machine. The thresher output quality , composition of tailing return, and separating loss were analyzed from the sampels taken at each treatment. A separate experiment for measurement opf the power requirement of the head-feeding type thresher was also performed. The results are summarized as follows : 1. There was a difference in the thresher output quality between rice varieties. In case of wet-paddy threshing at 550 rpm , grains with branchlet and torn heads for the Suweon 264 were 12 % and 7 % of the total output in weight, respectively, and for the Minehikari 4.5 % and 2 % respectively. In case of dry paddy threshing , those for the Suweon 264 were 8 % and 5% , and for the Minehikari 4% and 1% respectively. However, those for the Milyang 23 , which is highly susceptable to shattering, were much lower with 1 % and 0.5% respectively, regardless of the moisture content of the paddy. Therefore, it is desirable to breed rice varieties of the same physical properties as well as to improve a thresher adaptable to all the varieties. Torn heads, which increased with the moisture content of rall the varieties except the Milyang 23 , decreased as the cylinder speed increased, but grains with branchlet didnt decrease. The damaged kernels increased with the cylinder speed. 3. The thresher output quality was not affected much by the feed rate. But grains with branchlet and torn heads increased slightly with the feed rate for the head-feeding type thresher since higher resistance lowered at the cylinder speed. 4. In order to reduce grains with branchlet and torn heads in wet-paddy threshing , it is desirable to improve the head-feeding type thresher by developing a new type of cylinder which to not give excess impact on kernels or a concave which has differenct sizes of holes at different locations along the cylinder. 5. For the head-feeding type thresher, there was a difference in separating loss between the varieties. At the cylinder speed of 600 rpm the separating losses for the Minehikari and the Suweon 264 were 1.2% and 0.6% respectively. The separating loss of the head-feeding type thresher was not affected by the moisture content of paddy while that of the Mini-aged thresher increased with the moisture content. 6. From the analysis of the tailings return , to appeared that the tailings return mechanism didn't function properly because lots of single grains and rubbishes were unnecessarily returned. 7. Adding a vibrating sieve to the head-feeding type thresher could increase the efficiency of separation. Consequently , the tailing return mechanism would function properly since unnecessary return could be educed greatly. 8. The power required for the head-feeding type thresher was not affected by the moisture content of paddy, but the average power increased linearly with the feed rate. The power also increased with the cylinder speed.

• The Korean Journal of Mycology
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• v.41 no.3
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• pp.172-180
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• 2013

Grey mold infection rate in tomato was investigated with the inoculation of dead flowers on Botrytis selective media. The grey mold infection rate of flower after fruiting were higher in the order of after 45 days, after 25 days, and fruiting day with 100%, 87% and 65%, respectively. The number of infected flowers were increased with time increase after the flowering before fruiting. BSM (Botrytis selective medium) was used to check grey mold infection rate depending on the flowering stage and cultivar. Grey mold infection rate depending on the flowering stage was similar in all the beef-tomato cultivar as 1.5~5% at preflowering, 1.5~45% at flowering and 75~90% at fruiting. On the other hand, cherry tomato cultivar "KoKo" had lower infection rates of 0~3.5% at pre-flowering, 10~30% at flowering and 20~50% at fruiting. These resulted from the fact that beaf-tomato cultivar have much bigger flowers and larger amount of pollens compared to those of cherry tomato cultivar. The amounts of falling pollens of Botrytis spp. were checked for beaf-tomato cultivar and cherry tomato cultivar using BSTM. The amounts of falling pollens were increased as growth period was extended, and the amount of spores increased rapidly during the outbreak of grey mold. Twelve field trials in Buyeo and Iksan areas showed that Fluazinam, and Diethofencarb+Carbendazim were effective fungicides to control tomato grey mold, and these results were similar to those of field trials with BSTM. This is the first report of Fluazinam as a effective fungicide for the control of grey mold of tomato even though it has not been registered yet for the control of gray mold in tomato.

• The Journal of Korean Medicine
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• v.20 no.2
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• pp.108-120
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• 1999

In this study, body weight levels of glucose, insulin and triglyceride in blood and glucosidase activity of the small intestine were investigated to determine the effect of Sangbaegpitang and Supungsungiwhan on the glucose metabolism of db/db mice. The GLUT4 mRNA of muscle tissue and the Acetyl CoA Carboxylase and the activation rate of GLUT2 mRNA of liver tissue were measured by the reverse transcription-polymerase chain reaction method and by the vitro transcription. The results were obtained as follows: 1. In the Sangbaegpitang administration group, (1) The level of triglyceride was decreased significantly and the glucosidase activity of the small intestine was inhibited remarkably, (2) The amounts of the GLUT4 mRNA in muscle tissue and Acetyl CoA Carboxylase mRNA in liver tissue were increased significantly. (3) Though glucose level in both fasting and non-fasting, were decreased and the insulin level in blood was increased, the results showed no statistical significance. 2. In the Supungsungiwhan administration group, (1) The levels of glucose and triglyceride were decreased significantly in the blood of non-fasting animals. (2) The glucosidase activity of small intestine was inhibited markedly and the amounts of GLUT4 mRNA of muscle tissue and GLUT2 mRNA of liver tissue were increased significantly. (3) The glucose levels in the fasting group were reduced, while insulin level was increased but showed no statistical significance, Based on the above results, our conclusions are as follows: Sangbaegpitang & Supungsungiwhan are thought to be capable of inhibiting the activity glucosidase, the enzyme which influences carbohydrate metabolism in the small intestine of db/db mice(the experimental diabetic model) and delaying the absorption of carbohydrate, thus proving effective on inhibiting the increase of non-fasting glucose level effectively. Futhermore Sangbaegpitang and Supungsungiwhan are though: to be capable of preventing the composition of free fatty acids by restoring the production of GLUT4 mRNA of muscle tissues and GLUT2 mRNA of liver tissues. Those results suggests that above prescriptions can be applied to non-insulin dependent diabetes mellitus in order to improve insulin resistance.

• International Journal of High-Rise Buildings
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• v.10 no.4
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• pp.345-364
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• 2021

Developments in the understanding of fire behaviour for large open-plan spaces typical of tall buildings have been greatly outpaced by the rate at which these buildings are being constructed and their characteristics changed. Numerous high-profile fire-induced failures have highlighted the inadequacy of existing tools and standards for fire engineering when applied to highly-optimised modern tall buildings. With the continued increase in height and complexity of tall buildings, the risk to the occupants from fire-induced structural collapse increases, thus understanding the performance of complex structural systems under fire exposure is imperative. Therefore, an accurate representation of the design fire for open-plan compartments is required for the purposes of design. This will allow for knowledge-driven, quantifiable factors of safety to be used in the design of highly optimised modern tall buildings. In this paper, we review the state-of-the-art experimental research on large open-plan compartment fires from the past three decades. We have assimilated results collected from 37 large-scale compartment fire experiments of the open-plan type conducted from 1993 to 2019, covering a range of compartment and fuel characteristics. Spatial and temporal distributions of the heat fluxes imposed on compartment ceilings are estimated from the data. The complexity of the compartment fire dynamics is highlighted by the large differences in the data collected, which currently complicates the development of engineering tools based on physical models. Despite the large variability, this analysis shows that the orders of magnitude of the thermal exposure are defined by the ratio of flame spread and burnout front velocities (V_S / V_BO), which enables the grouping of open-plan compartment fires into three distinct modes of fire spread. Each mode is found to exhibit a characteristic order of magnitude and temporal distribution of thermal exposure. The results show that the magnitude of the thermal exposure for each mode are not consistent with existing performance-based design models, nevertheless, our analysis offers a new pathway for defining thermal exposure from realistic fire scenarios in large open-plan compartments.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.46-52
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• 2015

A leaching kinetics was conducted for the purpose of recovery of praseodymium in sulfuric acid ($H_2SO_4$) from REE slag concentrated by the smelting reduction process in an arc furnace as a reactant. The concentration of $H_2SO_4$ was fixed at an excess ratio under the condition of slurry density of 1.500 g slag/L, 0.3 mol $H_2SO_4$, and the effect of temperatures was investigated under the condition of 30 to $80^{\circ}C$. As a result, praseodymium oxide ($Pr_6O_{11}$) existing in the slag was completely converted into praseodymium sulfate ($Pr_2(SO_4)_3{\cdot}8H_2O$) after the leaching of 5 h. On the basis of the shrinking core model with a shape of sphere, the first leaching reaction was determined by chemical reaction mechanism. Generally, the solubility of pure REEs decreases with the increase of leaching temperatures in sulfuric acid, but REE slag was oppositely increased with increasing temperatures. It occurs because the ash layer included in the slag is affected as a resistance against the leaching. By using the Arrhenius expression, the apparent activation energy of the first chemical reaction was determined to be $9.195kJmol^{-1}$. In the second stage, the leaching rate is determined by the ash layer diffusion mechanism. The apparent activation energy of the second ash layer diffusion was determined to be $19.106kJmol^{-1}$. These relative low activation energy values were obtained by the existence of unreacted ash layer in the REE slag.

• Nutrition Research and Practice
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• v.9 no.4
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• pp.385-392
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• 2015

BACKGROUND/OBJECTIVES: Recent studies have reported an association of the angiotensin II type 2 receptor (AT2R) 3123Cytosine/Adenine (3123C/A) polymorphism with essential hypertension and cardiovascular diseases. The purpose of the study was to investigate whether the AT2R 3123C/A polymorphism affects blood pressure for free-living hypertensive men during a 5-month intervention period. SUBJECTS/METHODS: The subjects were free-living hypertensive Japanese men aged 40 to 75 years who agreed to intervention in the period from 2004 to 2011. Detection of the AT2R 3123C/A polymorphism was determined by polymerase chain reaction. The dietary intervention was designed to decrease salt level and to increase potassium level through cooking instructions and self-monitoring of the diet. The exercise session consisted of activities such as stretching, resistance training, and walking. Blood pressure, urinary sodium and potassium excretion, dietary and lifestyle data, and non-fasting venous blood sample were collected at baseline and after the intervention period. RESULTS: Thirty nine subjects were eligible for participation and the follow-up rate was 97.4%. The C allele proportion was 57.9%. AT2R 3123C/A polymorphism was X-chromosome-linked, therefore we analyzed the C and A genotypes. At baseline, no significant differences were observed between the genotype groups. After the intervention, there were no significant differences in lifestyle habit between the groups. Nevertheless, the estimated salt excretion (g/day) was significantly decreased only in the C genotype (13.0-10.3, P = 0.031). No significant change was observed in systolic blood pressure (SBP) (mmHg) in the A genotype, but a significant decrease was observed in the C genotype (150.0-141.5, P = 0.024). CONCLUSTIONS: In the C genotype, it might be easy to improve SBP through lifestyle intervention in free-living hypertensive Japanese men, however generalization could not be achieved by the small sample size.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.207-216
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• 2003

Drilled deep foundations of large diameter are often used for foundations of transmission towers. As tower structures become larger in modern society, there is a need of more efficient and economical design of large-diameter drilled deep foundations. Reinforced drilled deep foundations are popular in Japan for the foundation of tower structures. Stiffeners attached to the shaft of the foundation are used to increase the shaft resistance. This study aims at analyzing the effect of reinforcement with large-diameter drilled deep foundations based on numerical analysis of the representative soil and rock conditions in Korea. The numerical analyses are conducted to analyze the reinforcement effect of various stiffener conditions of number, inclination, location and length. Regarding to number of stiffeners, the effect of reinforcement for weathered and soft rocks increases proportionally as the number of stiffeners increases. For weathered soil, however, the effect of reinforcement increases at a lower rate. The effect of stiffener location is nearly negligible for axially loading cases, while it is significant for laterally loading cases. For the laterally loading cases, upper locations of stiffener give greater reinforcement effect than that of lower location. For stiffener inclinations of axial loading cases, a stiffener inclination equal to 60$^{\circ}$ gives the greatest reinforcement effect.

• Corrosion Science and Technology
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• v.14 no.2
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• pp.99-105
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• 2015

The structures of reinforced concrete have been extensively increased with rapid development of industrial society. Futhermore, these reinforced concretes are easy to expose to severe corrosive environments such as seawater, contaminated water, acid rain and seashore etc.. Thus, corrosion problem of steel bar embedded in concrete is very important in terms of safety and economical point of view. In this study, specimens having six different coating thickness (W/C:0.5) were prepared and immersed in flowing seawater for five years to evaluate the effect of coating thickness and immersion time on corrosion property. The polarization characteristics of these embedded steel bars were investigated using electrochemical methods such as corrosion potential, anodic polarization curve, and impedance. At the 20-day immersion, the corrosion potentials exhibited increasingly nobler values with coating thickness. However, after 5-yr. immersion their values were shifted in the negative direction, and the relationship between corrosion potential and coating thickness was not shown. Although 5-yr. immersion lowered corrosion potential, 5-yr. immersion did not increase corrosion rate. In addition, after 5-yr. immersion, the thinner cover thickness, corrosion current density was decreased with thinning coating thickness. It is due to the fact that ease incorporation of water, dissolved oxygen and chloride ion into a steel surface caused corrosion and hence, leaded to the formation of corrosion product. The corrosion product plays the role as a corrosion barrier and increases polarization resistance. The corrosion probability evaluated depending on corrosion potential may not be a good method for predicting corrosion probability. Hence, the parameters including cover thickness and passed aged years as well as corrosion potential is suggested to be considered for better assessment of corrosion probability of reinforced steel exposed to partially or fully in marine environment for long years.

• Journal of the Korea Concrete Institute
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• v.20 no.3
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• pp.405-412
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• 2008

Six alkali-activated (AA) concrete mixes were tested to explore the significance and limitations of developing an environmental friendly concrete. Ground granulated blast-furnace slag and powder typed sodium silicate were selected as source material and an alkaline activator, respectively. The main parameter investigated was the replacement level of lightweight fine aggregate to the natural sand. Workability and mechanical properties of lightweight AA concrete were measured: the variation of slump with time, the rate of compressive strength development, the splitting tensile strength, the moduli of rupture and elasticity, the stress-strain relationship, the bond resistance and shrinkage strain. Test results showed that the compressive strength of lightweight AA concrete sharply decreased when the replacement level of lightweight fine aggregate exceeded 30%. In particular, the increase in the discontinuous grading of lightweight aggregate resulted in the deterioration of the mechanical properties of concrete tested. The measured properties of lightweight AA concrete were also compared, wherever possible, with the results obtained from the design equations specified in ACI 318-05 or EC 2, depending on the relevance, and the results predicted from the empirical equations proposed by Slate et al. for lightweight ordinary Portland cement concrete. The stress-strain curves of different concrete were compared with predictions obtained from the mathematical model proposed by Tasnimi. The measured mechanical properties of lightweight AA concrete generally showed little agreement with the predictions obtained from these equations.