• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.2
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• pp.138-144
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• 2023

In this study, the effect of electrochemical treatment in mitigating alkali leaching into an aquatic environment was investigated. To modify the surface of cement paste, 1000 mA/m² of the direct current was passed through anodic graphite to the external mesh for 4 weeks. Then, the cement paste specimen was exposed to still water in air-tight condition to prevent natural healing of alkali leaching in the water. For 100 days of monitoring in water, the pH value was marginally increased at the electrochemical treatment, while control specimen ranked to the even higher pH accounting for 13.2 in the pH. Moreover, after the pH monitoring, the pH profile for the paste specimen indicated that the electrochemical treatment was effective in securing the higher alkalinity of cement matrix. The water obtained from alkali leaching process, was used to ecological test for Daphnia magna. It was evident that the electrochemical treatment had minimal adverse effect on ecological impact, while control specimen mostly immobilized the standard Daphnia magna.

• Journal of the Korean Geotechnical Society
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• v.39 no.7
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• pp.17-30
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• 2023

This study investigates the impact of water immersion and high temperature on the shear strength of cemented sand through direct shear tests. Standard Jumunjin sand was used and cemented with binders, such as ultra-rapid hardening cement and an epoxy aqueous solution. The binder was mixed at concentrations of 4%, 8%, or 12%. Subsequently, cylindrical cemented specimens with a diameter of 64 mm and height of 25 mm were produced using compaction. The curing period was three days, and the specimens were cured under dry air, immersion, and heating conditions. The heating condition involved subjecting the immersed specimens to a microwave oven three times for three minutes to achieve an internal temperature of approximately 90℃. Regardless of the binder type, the cohesion of the cemented sand increased with higher binder content, whereas the internal friction angle exhibited a slight increase or decrease. Compared with ultra-rapid hardening cemented sand, epoxy-cemented sand displayed an average cohesion that was five times higher and an internal friction angle that was 10° higher. Overall, irrespective of binder type, the shear strength decreased during water immersion and increased during heating. Notably, the epoxy-cemented sand exhibited a three-fold increase in cohesion and a more than 20° increase in the internal friction angle during heating.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.3
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• pp.145-151
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• 2023

In order to extend shelf life for rockfish fillets by modified atmosphere packaging (MAP), different package atmospheres were compared in the product quality preservation. Firstly, CO₂ solubility was measured at 0, 5, 10, and 15℃ to be incorporated into the mathematical model to predict the volume and CO₂ concentration of the package at expected storage temperature. The CO₂ solubility given in Henry's constant decreased with temperature to be fitted with a linear equation. Then air packaging as control and four MAP conditions of 100 g fillets were prepared and stored for duration of 5 days at 10℃ to compare them in the quality preservation effect. Four MAP conditions employed were CO₂(60):O₂(30):N₂(10), CO₂(60):O₂(0):N₂(40), CO₂(30):O₂(30):N₂(40) andCO₂(30):O₂(0):N₂(70). MAP conditions with high CO₂ concentration inhibited total aerobic bacteria, and the conditions containing O₂ led to low TVB-N. MAP of CO₂(60):O₂(30):N₂(10) was found to be the best condition for rockfish fillet preservation considering total aerobic bacteria growth and nitrogenous volatiles production.

• Korean Journal of Organic Agriculture
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• v.32 no.1
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• pp.75-90
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• 2024

Biochar is a solid substance with a high carbon content, as it is made out of biomass pyrolyzed under the condition of limited oxygen. This product has attracted attention as an environment-friendly soil amendment because it contributes to carbon neutrally and has improvement effects on the soil environment. This study conducted an experiment to evaluate soil physiochemical properties and microbial community changes in a melon greenhouse according to the applied amount of biochar to investigate the growth characteristics and yields of melons accordingly. In soil physical properties, an increase in the applied amount of biochar resulted in a decrease in bulk density and an increase in porosity of the soil, improving air permeability. In soil chemical properties, an increase in the applied amount of biochar led to a increasing of pH, organic matter and available phosphate content. In the growth characteristics of melons, there was a growing tendency of plant height, leaf length and leaf width according to the increasing application of biochar until 10,000 kg/ha. Moreover, melon yields also increased as the amount of biochar, 13~16% higher in 10,000 kg/ha biochar application than no treatment. Compared differences among microbial communities in the soil according to the application of biochar and found that plant beneficial bacteria dominated in biochar treatments. This study demonstrated the potential of biochar as an effective soil amendment in melon greenhouse by showing improvements in soil physicochemical properties and microbial communities.

• Safety and Health at Work
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• v.14 no.4
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• pp.457-466
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• 2023

Background: During hot environment work tasks with whole-body enclosed anti-bioaerosol suit, the combined effect of heavy sweating and exhaled hot humid air may cause the N95 medical respirator to saturate with water/sweat (i.e., water-blocking). Methods: 32 young male subjects with different body mass indexes (BMI) in whole-body protection (N95 medical respirator + one-piece protective suit + head covering + protective face screen + gloves + shoe covers) were asked to simulate waste collecting from each isolated room in a seven-story building at 27-28℃, and the weight, inhalation resistance (R_f), and aerosol penetration of the respirator before worn and after water-blocking were analyzed. Results: All subjects reported water-blocking asphyxia of the N95 respirators within 36-67 min of the task. When water-blocking occurred, the R_f and 10-200 nm total aerosol penetration (P_t) of the respirators reached up to 1270-1810 Pa and 17.3-23.3%, respectively, which were 10 and 8 times of that before wearing. The most penetration particle size of the respirators increased from 49-65 nm before worn to 115-154 nm under water-blocking condition, and the corresponding maximum size-dependent aerosol penetration increased from 2.5-3.5% to 20-27%. With the increase of BMI, the water-blocking occurrence time firstly increased then reduced, while the R_f, P_t, and absorbed water all increased significantly. Conclusions: This study reveals respirator water-blocking and its serious negative impacts on respiratory protection. When performing moderate-to-high-load tasks with whole-body protection in a hot environment, it is recommended that respirator be replaced with a new one at least every hour to avoid water-blocking asphyxia.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.2
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• pp.65-80
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• 1980

Processing conditions of the krill products such as paste food, krill protein concentrate, seasoned dried krill, powdered seasoning, meat ball, and snack have been examined and the quality was evaluated chemically and organoleptically. In the processing of paste food, krill juice was yielded $71\%$ and krill scrap $29\%$. The yields of paste and broth from the krill juice showed $53\%$ and $43\%$, respectively. In amino acid composition of the krill paste, proline, glutamic acid, aspartic acid, lysine, and leucine were abundant, while histidine, methionine, tyrosine, serine and threonine were poor. The optimum condition for solvent extraction in the processing of krill protein concentrate was the 5 times repetitive extraction using isopropyl alcohol at $80^{\circ}C$ for 5 mins. The yield of krill protein concentrate when used fresh frozen materials was $10.2\%$ in isopropyl alcohol solvent and $8.8\% in ethyl alcohol, and when used preboiled frozen materials, the yield was $13.0\%$ in isopropyl alcohol and $11.8\%$ in ethyl alcohol. Amino acid composition of krill protein concentrate showed a resemblance to that of fresh frozen krill meat. In quality comparison of the seasoned dried krill, hot air dried krill was excellent as raw materials and sun dried krill was slightly inferior to hot air dried krill, but preboiled frozen krill showed the poorest quality. The result of quality evaluation for seasoning made by combination of dried powdered krill, parched powdered sesame, salt, powdered beef extract, monosodium glutamate, powdered red pepper and ground pepper showed that the hot air dried krill was good in color and sundried krill was favorable in flavor. When krill meat ball was prepared using wheat flour, monosodium glutamate and salt as side materials, the quality of the products added up to $52\%$ of krill meat was good and the difference in quality upon the results of the organoleptic test for raw materials was not recognizable between fresh frozen and preboiled frozen krill. In the experiment for determining the proper amount of materials such as dried Powdered krill, $\alpha-starch$, sweet potato starch, sugar, salt, monosodium glutamate, glycine, potassium tartarate, ammonium bicarbonate, and sodium bicarbonate in processing krill snack, sample B(containing $7.7\%$ of dried powdered krill) and sampleC (containing $10.8\%$ of dried powdered krill) showed the most palatable taste from the view point of organoleptic test. Sweet potato starch in testing side materials was good in the comparison of suitability for processing krill snack. Corn starch and kudzu starch were slightly inferior to sweet potato starch, while wheat flour was not proper for processing the snack. In the experiment on frying method, oil frying showed better effect than salt frying and the suitable range of frying temperature was $210-215^{\circ}C$.

• The Korean Journal of Air & Space Law and Policy
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• v.21 no.1
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• pp.169-189
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• 2006

In 2007, KSLV(Korea Small Launching Vehicle) that we made at Goheung National Space Center is going to launch and promotes of our space exploration systematically and 'Space Exploration Promotion Act' was enter into force. 'Space Exploration Promotion Act' article 3, section 1, as is prescribing "Korean government keeps the space treaties contracted with other countries and international organizations and pursues after peaceful uses of outer space." The representative international treaties are Outer Space Treaty (1967) and Liability Convention (1972) etc. In Liability convention article 2, "A launching State shall be absolutely liable to pay compensation for damage caused by its space object on the surface of the earth or to aircraft in flight. The important content of the art. 2 is the responsible entity is the 'State' not the 'Company'. According by Korean Space Exploration Act art. 14, person who launches space objects according to art. 8 and art. 11 must bear the liability for damages owing to space accidents of the space objects. Could Korean government apply the Products Liability Act which is enter into force from July 1, 2002 to space launching person? And what is the contact type between Korea Aerospace Research Institute(KARl) and Russia manufacturer. Is that a Co-Development contract or Licence Product contract? And there is no exemption clause to waive the Russia manufacturer's liability which we could find it from other similar contract condition. If there is no exemption clause to the Russia manufacturer, could we apply the Korean Products Liability Act to Russia one? The most important legal point is whether we could apply the Korean Products Liability Act to the main component company. According by the art. 17 of the contract between KARl and the company, KARl already apply the Products Liability Act to the main component company. For reference, we need to examine the Appalachian Insurance co. v. McDonnell Douglas case, this case is that long distance electricity communication satellite of Western Union Telegraph company possessions fails on track entry. In Western Union's insurance company supplied to Western Union with insurance of $ 105 millions, which has the satellite regard as entirely damage. Five insurance companies -Appalachian insurance company, Commonwealth insurance company, Industrial Indemnity, Mutual Marine Office, Northbrook Excess & Surplus insurance company- went to court against McDonnell Douglases, Morton Thiokol and Hitco company to inquire for fault and strict liability of product. By the Appalachian Insurance co. v. McDonnell Douglas case, KARl should waiver the main component's product liability burden. And we could study the possibility of the adapt 'Government Contractor Defense' theory to the main component company.

• Horticultural Science & Technology
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• v.33 no.3
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• pp.375-382
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• 2015

A controlled atmosphere (CA) regimen was optimized during 3 consecutive harvest seasons as the basis of practical modified atmosphere packaging (MAP) storage for quality maintenance and extension of storage potential of fresh Ligularia fischeri leaves. Leaves were harvested in April or May and forced-air cooled to $4^{\circ}C$ before punch-hole MAP (control, where gas concentrations were same as air) and CA treatments. CA regimens adjusted stepwise during 3 experimental years were: 1 and 3% $O_2$, respectively combined with 5 and 10% $CO_2$ in the first year, 3% $O_2$ fixed in combination with 0, 2.5, and 5% $CO_2$ in the second year, and 3% $O_2$ fixed in combination with 2.5 and 5% $CO_2$ in the third year. In the first year, higher incidence of black discoloration was observed with the reduction of respiration under 10% $CO_2$ CA conditions regardless of $O_2$ levels at 1 or 3%. In the second and third year, the incidence of the disorder seemed not to be clearly relevant to CA conditions showing slightly higher incidence only after 4- or 5-week storage + 5-day shelf life. Although texture and appearance quality were maintained better under the 3% $O_2$ + 2.5% $CO_2$condition after 4-week storage + 5-day shelf life, effects of CA on the extension of storage period was slight. Overall results indicated that Ligularia fischeri leaves are very susceptible to $CO_2$ injury. $CO_2$ concentration should be adjusted below 2.5% for safe and effective CA or MAP storage to maintain quality even during short-term storage.

• Journal of the Korean Institute of Landscape Architecture
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• v.37 no.4
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• pp.64-71
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• 2009

Excessive soil organic matter (SOM) is detrimental to turfgrass quality when used intensively in sand-based root zones, thereby affecting the sustainability of turfgrass systems. As part of a major project examining the sustainable management of SOM on golf greens, microbial decomposition on soil organic matter accumulation with depth was assessed and the effect of soil air-condition improvement and Ca fertilization was investigated by soil microbial respiration (SMR). Three soil samples from three depths(0~5, 5~10, and 10~15cm) of 5 year and 30 year old green were analyzed for SOM content. In 30 year old green, SMR and dehydrogenase activity(DHA) were analyzed to assess the soil microbial decomposition with depth. It was then divided into 4 plots: untreated as a control, dolomite-treated, 0~5cm deep section-removed, and 0~5 cm deep section-removed+dolomite-treated. After treatment, three soil samples were taken at 1, 2 and 4 weeks by the above-mentioned method, and analyzed for SMR to better understand SOM decomposition. SOM accumulation in the 0~5cm depth of golf greens can be controlled by intensive cultivation such as coring, but below 5cm is more difficult as the results showed that SOM content below 5cm increased over time. Soil microbial decomposition of organic matter will be necessary to reduce SOM accumulation, but SMR below 5cm was low and wasn't significantly altered by increasing exposure to air and fertilizing with Ca. As a result, aeration treatments such as coring and Ca fertilization might not be effective at improving soil microbial decomposition below 5cm depth in aged greens.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.13
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• pp.93-105
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• 1973

Differential tolerance of rice varieties, Tongil and Mangyung(or Milsung) varieties, against herbicides combined with Simetryne was investigated by the rate of application in 4 places; Jeonju, Gwangju, Iri and Milyang, whose soil textures were Lic, Sic, CL and Lic respectively. The results are summarized as follows: 1) Jeonju a. Initial crop injury At the rate of 2kg/10a prod. no initial crop injury was caused(both to Mangyung and Tongil varieties) on light clay soil, even when treated at high temperature of $30^{\circ}C$ and above. Crop injury was first caused at 3kg/l0a prod. to Tongil variety and the damage increased in proportion to the increase of application rate, while no crop injury was caused to Mangyung variety even at high rate of 5kg/l0a prod. b. Yield Tongil variety: Under high temperature condition in a vinyl house no statistical difference was observed between treated and hand weeding plot at the rates of 3kg/l0a prod. and below. Under air temperature conditions no statistical difference was observed between treated and hand weeding plot at the rates of 4kg/l0a prod. and below. Mangyung variety: No statistical difference was observed between treated and hand weeding plot at the rates of 5kg/l0a prod. and below both under air and high temperature conditions. 2) Gwangju a. Initial crop injury Although almost the same tendency as in Jeonju was observed, a little lighter crop injury was observed in general in Gwangju than in Jeonju at the time of application. And so, no crop injury was caused to Tongil variety until 4kg/l0a prod. and above. b. Yield Tongil variety: No statistical difference was observed between treated and hand weeding plot at 4kg/l0a prod. and below. Mangyung variety: No statistical difference was observed between treated and hand weeding plot at 4kg/l0a prod. and below. 3) Iri No crop injury was caused both to Tongil and Mangyung varieties at 4kg/l0a prod. and below. Also, no reduction of grain yield was observed. 4) Milyang A little lighter crop injury was observed in general. No crop injury was caused to Milsung variety at 5kg/l0a prod. ; Only a slight crop injury was caused to Tongil variety. Yield: No statistical difference was observed between treated and hand weeding plot both of Tongil and Milsung varieties even at 5kg/l0a prod. and below.