• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.223-228
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• 2000

Although construction company try to get good quality control it's enough to study about developing objective evaluation method and checking quality method. It is important to meaning concrete quality at placing point, immediate quality checking method is limited. The purpose of this study is to develop new method to know early 28-day concrete for getting faithful quality control. The results of this study are as follows :1) With sealed molds, reduced moisture volatilization to more than 50% and enlarged 20% accelerated compressive strength than before one. 2) Accelerated compressive strength of concrete specimen shows higher strength when it was in the air for long time 3)Interrelation with 7-day and 28-day strength were 0.781,0.90, It is higher than before one

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.2
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• pp.277-284
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• 1998

For the purpose of comparing the shear bond strengths of pit and fissure sealants, and finding out the more efficient method of tooth surface treatment when the etched surface is contaminaed by saliva or moisture, an experiment was performed on 3 types of pit and fissure sealants. 120 extracted human molars were divided into 3 groups, each of which was composed of 40 specimens sealed with Helioseal, Teethmate-F and Fuji III respectively. And each groups was again divided into 4 subgroups according to tooth surface treatment. The shear bond strengths of each groups and subgroup was measured and statistically analyzed. The results obtained were as follows : 1. Shear bond strengths of nonfluoridated resin sealant, Helioseal were shown to be higher than those of fluoridated resin sealant, Teethmate-F, but, not significantly different. 2. Shear bond strengths of GI sealant, Fuji III were to be markedly lower than those of two resin sealants. 3. When there is moisture contamination, applying primer under sealant(Group IV) results in a significantly stronger bond strength of sealant to enamel than when using sealant alone(Group II) in case of all sealants. 4. When there is no moisture contamination, using primer under sealant (Group III) results in bond strength equivalent to bond strength on using sealant alone (Group I). 5. Based on the results above, it was demonstrated that the bond of sealant to tooth surface is greatly affected by saliva contamination and that the complete tooth isolation method should be fully emphasized. The application of primer is recommended when performing sealant under the environment very susceptible to saliva contamination.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.406-408
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• 2019

The motor applied to electric water pump used in automobiles is the canned type motor structure. The rotor, which is the driving component of the motor, is located in the bulkhead structure of the plastic injection molding, and rotates while immersed in the antifreeze. Plastic Injection Stator is placed on the outside of the bulkhead structure so that the rotor can rotate. The configuration of the rotor consists of magnet, core and shaft. In the case of magnet and core, it is very important to keep the parts sealed because it is a material that is corroded by moisture. When mounted on a vehicle, it must be capable of driving at $120^{\circ}C$ ambient conditions and should not leak under pressure of 1 bar or more. In this paper, we designed and implemented a Leak inspection automation system using helium to check the defects of the electric water pump developed satisfying this condition.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.23 no.3
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• pp.163-171
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• 2017

Effects of different packaging methods for maintaining the shelf life and postharvest quality of iceberg lettuce (Lactuca sativa L.) were studied after harvesting in summer season. Lettuce heads were packaged in plastic crate with or without different films such as (A) Individual lettuce head sealed packaging with linear low density polyethylene (LLDPE) film; (B) Packaging lettuce head in plastic crate and wrapped with LLDPE film; (C): Individual lettuce head sealed packaging with perforated high density polyethylene (HDPE) film; (D) Packaging lettuce head in plastic crate and wrapped with perforated HDPE; and (E) Packaging lettuce head in plastic crate without any film (control), and stored at $2^{\circ}C$ for 35 days. Several quality parameters such as fresh weight loss, SPAD (soil & plant analyzer development) meter value, respiration rate, moisture content and appearance of lettuce were investigated. The lettuce wrapped with individually-sealed LLDPE film showed the lowest weight loss and the highest SPAD value rendering the best appearance index among the treataments throughout the three-week storage period at $2^{\circ}C$. Extending the freshness of iceberg lettuce during low temperature storage will definitely increase the salability potential in the domestic market even during summer season.

• Conservation Science in Museum
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• v.16
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• pp.96-113
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• 2015

High-barrier films are used to store cultural heritage objects in a safe environment sealed from oxygen and moisture. One of the high-barrier films use populary E manufactured by Japanese company M from the 1990's. However, this product has stayed in wide use, due to dearth of research on related subjects - including studies comparing it with other similar products-, in spite of the fact that high price information about its characteristics and environmental conditions is largely lacking. This study examines the characteristics of a number of high-barrier films with the goal to establish environmental standards for safer conservation of cultural heritage objects. E by the Japanese manufacturer M is compared with four other films; an electronics packaging films by a Korean firm, a film specially produced for the purposes of experiment in this study and a zipper bag-type film. Experiments were performed to compare the properties and gas blocking ability of the films by looking at their cross-section and measuring the thickness, tensile strength, elongation, absorbance of UV and visible light, yellowing and the permeability for oxygen and vapor. Based on these experiments, there are observed changes under different environmental conditions and depending on the length of use through temparature and humidification reproucing test. The results showed that while the high-barrier film by the Korean manufacturer was suitable for use as a packaging material for cultural heritage objects, the zipper bag-type film (P) was ill-adapted for this purpose. Based on the experiments reproducing the real-world environment, the length of useful life was also determined for each.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.4
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• pp.447-453
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• 1986

Germination and seedling elongation of soybeans [cult. ‘Williams’] were measured at two temperatures (15 and 3$0^{\circ}C$), three seed water contents (30, 50, and 70%), and with and without polyethylene glycol-8000 (PEG) treatments. A split-plot design was used with four replications. Observations were made from two hours to eight days for each treatment combination. Seeds were soaked with 30% PEG solution with 0.2% thiram at 15 C for six days, rinsed with deionized water and dried at 25.5$^{\circ}C$ for three days. Ten treated or untreated seeds were placed on Whatman No. I (9 cm) filter paper in plastic petridishes to which sufficient deionized water was added to adjust seed moisture content to the desired level. The dishes were then sealed with parafilm and placed in a continuous programmed temperature chamber under dark condition. Seedling growth did not occur at either temperature when moisture content was 50 percent or less. Osmo-conditioning with PEG showed positive effects on seedling moisture uptake and seedling growth at 15$^{\circ}C$ but little effect at 3$0^{\circ}C$. Seedling moisture content increased rapidly early in the germination period and reached 60% at 15 C for 56 hours and at 3$0^{\circ}C$ for 28 hours. Seedling growth started when seed moisture reached a critical point of 60% at 15$^{\circ}C$, however, growth started after 20 hours of germination at 3$0^{\circ}C$. Seedlings of soybeans elongated more than four times faster at 3$0^{\circ}C$ than at 15$^{\circ}C$. Water uptake during germination was characterized by two phases in this experiment.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.1
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• pp.91-99
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• 1996

About 7.7 million tons of straw dry matter are being rotten during the monsoon. The objective of this trial was to develop a technique to preserve straw under wet condition. To simulate the moisture content of wet straw, a dry straw was deeped overnight in water. After draining the excess water, the wet straw(668 g moisture $kg^{-1}$) was divided into twenty fractions and preserved with 0, 30, 50 ro 70 g urea $kg^{-1}$ dry matter for either of 30, 60, 90, 120 or 180 days in sealed plastic container. Considering the colour, smell, fungal infestation and pH, the wert straw was preserved excellently up to 180 days when 50 or 70 g of urea per kg DM was used. Urea preservation increased the crude protein contents of straw by 3.6 to 6.4 times (174 to $364g{\cdot}kg^{-1}$) over that of the dry straw ($48g{\cdot}kg^{-1}$). Although the NDF content of straw was not effected by the level of urea or by the length of the preservation period, but the ADF content increased (p > 0.05) by 0.086 to $0.889g{\cdot}kg^{-1}$ straw DM for each g increase in the urea level. At 48 hours, the DM degradability of dry straw was $350g{\cdot}kg^{-1}$, which increased to $633g{\cdot}kg^{-1}$ when preserved with 50 g urea $kg^{-1}$ for 180 days. For the same straw, both the rate(0.0388 vs. 0.0136 fraction $h^{-1}$), the extent(717 vs. $631g{\cdot}kg^{-1}$) of straw degradation and the estimated ME(9.55 vs. $6.51MJ{\cdot}kg^{-1}$ straw DM) were higher in the preserved than the dry straw.

• Food Science and Preservation
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• v.14 no.1
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• pp.18-23
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• 2007

This study investigated the effectsof whiteness and packing conditions on the quality characteristics of milled rice during storage at $25^{\circ}C$. Three kinds of packing materials (kraft paper sealed polyethylene and perforated polyethylene) were used to pack milled rice of different whiteness grades (36, 38, 40 and 42). The moisture content and weight of milled rice packed in kraft paper dropped very rapidly compared to values from milled rice packed in polyethylene because of high gas exchange through the paper. On the other hand, the increase in fat acidity of milled rice packed in kraft paper was less than that of milled rice packed in polyethylene because the moisture content of paper-packed rice fell rapidly. The overall quality of cooked rice rose with whiteness, and dropped with extended storage. The overall eating quality of milled rice paced in perforated polyethylene was bestwhen rice was prepared for the table after 8 weeks of storage.

• Journal of The Korean Society of Grassland and Forage Science
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• v.27 no.3
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• pp.197-208
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• 2007

This study was carried out to investigate effects of increasing moisture content with or without supplementing inoculant (Lactobacillus plantarum) in TMR (total mixed ration) on its feed value. In case of exposing TMR to air, the lower the moisture level of TMR was, the less its apparent condition was changed. The time of spreading of molds tended to be faster in TMR with the higher moisture level. And also the odor was influenced by moisture content and inoculant supplement that is, sour odor was smelled from 24 hour after exposing TMR containing 35% and 50% moisture to air, but TMR supplemented with inoculant had sweet odor. The inner temperature of TMR containing 35% and 50% moisture without inoculant tended to increase continually after the lapse of 6 hours when the TMR was exposed to air. The inner temperature of TMR containing 35% moisture with inoculant tended to increase dramatically after the lapse of 48 hours when exposed to air, but that of TMR containing 50% moisture with inoculant tended to increase after 6 hours. The pH of TMR containing 15% was consistent regardless of exposing time to air, but that of TMR containing 35% and 50% moisture considerably increased after 12 and 24 hours, respectively. The concentration of $NH_3-N$ of TMR supplemented with inoculant was increased from 6 hours after exposure to air, while that or TMR without inoculant increased from 12 hours. Nutrient content or TMR tended to be increased with the increase of exposing time to air and storage time under sealed condition.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.132-135
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• 2004

High-performance concrete (HPC) may be expected to differ from usual concrete with respect to shrinkage behavior, and it shows high autogenous shrinkage due to the use of very low water-binder ratio (w/b) and various admixtures. Therefore, in order to minimize the shrinkage stress and to ensure the service life of concrete structure, volumetric change of HPC should be understood. In this study, small prisms made of HPC with w/b of 0.32 and blast-furnace slag content of $0\%,\;30\%,\;and\;50\%$ were prepared to measure the volumetric changes such as autogenous shrinkage, drying shrinkage, and swelling under three different curing conditions. It was observed that the concrete cured. sealed condition showed only autogenous shrinkage while the concrete let to dry condition at temperature of $20^{\circ}C$ and relative humidity of $60\%$ during the test period showed both autogenous and drying shrinkage. Moreover, the concrete exposed to dry condition after 2-day water curing swelled and then started to shrink with age. The total shrinkage (autogenous+drying) of this concrete was smaller than that of the concrete cured dry condition, especially at early-age. Therefore, the early-age moisture curing is very effective to control or minimize the volumetric change and its induced stress of HPC.