• 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.

• Korean Journal of Agricultural Science
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• v.12 no.2
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• pp.356-369
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• 1985

In Korea, inevitable researches for the blast control exactly started from 1927 by the organization of Office of Rural Development with the local extensive outbreak of panicle blast at Jeonlla Buk-Do Province in 1926. At present, the rice blast is still one of the most destructive and widespread diseases in spite of considerable contributions by rice scientists, particularly plant pathologists during last 55 years in Korea. Rice blast control and management are very difficult because of the marked variability in pathogenicity of the blast fungus. From the results obtained through the disease surveys during last 70 years, different 3 prevalence type of blast such as bimodal leaf-blast type, bimodal panicle-blast type and bimodal continual blast type were recognized. In generally speaking, pattern of blast outbreak is said to be characterized by severe outbreak of panicle blast after slight outbreak of leaf blast with discontinuity between leaf and panicle blast. So we have to pay much attention for successful management of panicle blast giving direct influence to rice yield. Main factors induce blast epidemic were pointed out to be breakdown of the disease resistance, nutritional unbalance such as excess application of nitrogen, delay of transplantation and longspell of rain fall by extensive surveys and researches on blast during last 70 years in Korea. The fact some of Japonica varieties such as Kokuryomiyako, Tamanishiki, Ginbozu and Pungok belong to varietal group A had been cultivated with extensive acrage over 30 years in this country should be mentioned by Korean rice scientists. Differences in field resistance between varieties in the same group are detectable and apparently small but sometimes epidemiologically significant differential effects may be found out in case of blast. Much more attention should be payed to accumulate the knowledges on field resistance for successful management of blast. Excess application of nitrogen is more effective to outbreak of panicle blast than that of leaf blast of IR varieties. In comparatively low level application of nitrogen infection rate of panicle blast of IR varieties is considerably high. Low temperature effects on outbreak of blast is very great. It results in remarkable increase of the inoculum potential on the leaf lesions and infection of panicle blast in leaf sheathes of IR varieties during the booting stage. In economic point of view, it is concluded that 5 times sprays of effective fungicides including 3 times before and 2 times after heading is good enough to control blast. We have experienced no one of control measures for blast is superior to all others. The integrated control measures was established as guideline of blast control around 1950 in Korea. This guideline must be helpful for rice growers as long as rice growing continue.

• Korean Journal of Poultry Science
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• v.8 no.1
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• pp.1-5
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• 1981

In trying to predict the effect of genetics on the broiler in the year 2000, this is a relatively short period of time as far as broiler genetics in concerned. Modern broiler genetics started around 1945 and tremendous gains when made in past 35 years. Futher improvements on broiler will depend on the evolution and revolution: 1. Evolution: (1) Growth rate has been made 4-5% per year. (2) Feed conversion has improved approximately 1% per year. (3) Abdominal fat is becoming a major complaint in broiler. (4) Because of the changing life-style, broiler meat sales in the future will be more and more in cut-up form. (5) Breeding for stress resistance and selection for docile temperament can be important in order to funker improve fled efficiency. (6) In female parent stock, reproduction characteristics are in many can negatively correlated with the desired broiler traits. (7) Egg production and hatchability in moot commercial parent nod m at a fairly high level. (8) In male parent stock, the heavier and mon super-meat-type male lines are desired to Product better broilers. 2. Revolution: Trying to forecast revolutionary change in broiler genetics is highly speculative, as sudden change are aften unpredictable. (1) Species hybridization, such as a turkey-chicken cross (2) Biochemical tools, such as blood typing. (3) Mutation breeding by radiation or chemical mutagentia. (4) Broiler breeding would be to change the phenotypic appearance by single gene, such as naked, wingless. (5) Changes in production techniques. such as growing in cage or growing in filtered air positive pressure houses.

• The Journal of the Petrological Society of Korea
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• v.16 no.3
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• pp.144-161
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• 2007

The studied Nangsan area is widely covered by the Jurassic biotite granodiorite, which is mainly light grey in color and medium-grained in texture. Results of the regional fracture pattern analysis for the granodiorite body are as follows. Strike directions of fractures show three dominant sets in terms of frequency order. The sets are in an order of a (1) $N80^{\circ}{\sim}90^{\circ}E$ (1st-order)>(2) $N70^{\circ}{\sim}80^{\circ}E$ (2nd-order)>(3) $NS{\sim}N10^{\circ}E$ (3rd-order). Spacings of the fractures are mostly predominant in less than 200 cm. Therefore, the granodiorite of the area has more potential for non-dimensional stones than dimension ones. And orientations of vertical quarrying planes can be also divided into two groups in terms of frequency $N14^{\circ}W{\sim}N16^{\circ}E$ (1st-order) and (2) $N78^{\circ}E{\sim}N88^{\circ}E$ (2nd-order). The orientations of the two groups are more or less different from those of the regional fracture patterns. These can be mainly attributed to the preferred orientations of microcrack developed in the quarries. Of physical properties, specific gravity, absorption ratio, porosity, compressive strength, tensile strength and abrasive hardness are 2.65, 0.28%, 0.73%, $1,628kg/cm^2,\;100kg/cm^2$ and 31, respectively. Contrary to the porosity, both granites of the Nangsan and Sogrisan areas show almost similar values of the abrasive hardness. These can be explained by the differences of Qz+Af modes, which can be regarded as an index for abrasive resistance. Meanwhile, it is anticipated that comprehensive understanding of the orientations of vertical quarrying planes and characteristics of various physical properties will be utilized as an important information for stone resources.

• Korean Journal of Microbiology
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• v.42 no.1
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• pp.12-18
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• 2006

Thirty five Salmonella enterica serovar Typhimurium strains were isolated from diarrheic patients and pigs in Gyeongbuk area from 2003 to 2004. All 35 strains (17 strains from diarrheic patients and 18 from pigs) were resistant to more than one drug and most of strains isolated from pigs were resistant to ampicillin, ohloram-phenicol, streptomycin, sulfamethoxazole-trimethoprime, tetracyclin and nalidixic acid. Each isolate was also screened or the presence of class I, II and III integron gene cassettes. Among 35 strains,3 out of 17 strains isolated from diarrheic patients, carried dhfrX-orfF-aadA2 integron gene cassette and among 18 strains isolated from diseased pigs, 11 strains carried dhfrX-orfF-aadA2 integron gene cassette and 1 strain carried aadA2 integron only. But any class II and class II integron gene cassette were not detected in 35 strains. Thirty five strains were divided by five pulsotypes. Thirty one strains out of thirty five were pulsotype A. Among the remaining 4 strains, one each strain belonged to pulsotype B, C, D and pulsotype E. This data of pulsotypes showed that the widespread of pulsotype A, Salmonella enterica serovar Typhimurium in human and pigs in Gyeongbuk area may have been caused by the dissemination of a few epidemic strains in this area. Thirteen strains contain dhfrX-orfF-aadA2 integron gene cassette showed pulsotype A and one strain contains dhfrX-orfF-aadA2 integron gene cassette showed pulsotype B. One strain contains aadA2 integron showed pulsotype E. But fifteen strains do not contain any integron showed pulsotype A.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.2
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• pp.213-230
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• 2008

The aim of this study was to analyze the initial movement and the stress distribution of each tooth and periodontal ligament during the lingual lever-arm retraction of 6 maxillary incisors using FEA. Two kinds of finite element models were produced: 2-properties model (simple model) and 24-properties model (multi model) according to the material property assignment. The subject was an adult male of 23 years old. The DICOM images through the CT of the patient were converted into the 3D image model of a skull using the Mimics (version 10.11, Materialise's interactive Medical Image Control System, Materialise, Belgium). After series of calculating, remeshing, exporting, importing process and volume mesh process was performed, FEA models were produced. FEA models are consisted of maxilla, maxillary central incisor, lateral incisor, canine, periodontal ligaments and lingual traction arm. The boundary conditions fixed the movements of posterior, sagittal and upper part of the model to the directions of X, Y, Z axis respectively. The model was set to be symmetrical to X axis. Through the center of resistance of maxilla complex, a retraction force of 200g was applied horizontally to the occlusal plane. Under this conditions, the initial movements and stress distributions were evaluated by 3D FEA. In the result, the amount of posterior movement was larger in the multi model than in the simple model as well as the amount of vertically rotation. The pattern of the posterior movement in the central incisors and lateral incisors was controlled tipping movement, and the amount was larger than in the canine. But the amount of root movement of the canine was larger than others. The incisor rotated downwardly and the canines upwardly around contact points of lateral incisor and canine in the both models. The values of stress are similar in the both simple and multi model.

• Tuberculosis and Respiratory Diseases
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• v.59 no.4
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• pp.368-373
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• 2005

Background : Bronchial anthracofibrosis usually manifest as a form of obstructive airway disease, and can be accompanied by parenchymal diseases such as pneumonia, and pulmonary tuberculosis. This study investigated the ventilatory dynamics according to the severity of bronchial stenosis in patients with bronchial anthracofibrosis. Method : One hundred and thirteen patients with bronchial anthracofibrosis that was confirmed by bronchoscopy and who had undergone a pulmonary function test were enrolled in this study group. The correlation coefficients between the pulmonary functional parameters and the number of lobes with bronchial stenosis were investigated. Results : The incidence of ventilatory dysfunction was 56(49.6%) for obstructive, 8(7.1%) for restrictive, 2(1.8%) for mixed, and 47(41.6%) for a normal pattern. The $FEV_1/FVC$, $FEF_{25{\sim}75%}$, $FEF_{25%}$, $FEF_{50%}$, $FEF_{75%}$, and PEF showed a significant negative correlation (p<0.05) and the Raw had a significant positive correlation with the number of lobes with bronchial stenosis(p<0.001). Conclusion : These findings suggest that the most common abnormality of the ventilatory function in bronchial anthracofibrosis is an obstructive pattern with a small airway dysfunction according to the severity of bronchial stenosis.

• Clean Technology
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• v.29 no.4
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• pp.255-261
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• 2023

Power semiconductors are semiconductors used for power conversion, transformation, distribution, and control. Recently, the global demand for high-voltage power semiconductors is increasing across various industrial fields, and optimization research on high-voltage IGBT components is urgently needed in these industries. For high-voltage IGBT development, setting the resistance value of the wafer and optimizing key unit processes are major variables in the electrical characteristics of the finished chip. Furthermore, the securing process and optimization of the technology to support high breakdown voltage is also important. Etching is a process of transferring the pattern of the mask circuit in the photolithography process to the wafer and removing unnecessary parts at the bottom of the photoresist film. Ion implantation is a process of injecting impurities along with thermal diffusion technology into the wafer substrate during the semiconductor manufacturing process. This process helps achieve a certain conductivity. In this study, dry etching and wet etching were controlled during field ring etching, which is an important process for forming a ring structure that supports the 3.3 kV breakdown voltage of IGBT, in order to analyze four conditions and form a stable body junction depth to secure the breakdown voltage. The field ring ion implantation process was optimized based on the TEG design by dividing it into four conditions. The wet etching 1-step method was advantageous in terms of process and work efficiency, and the ring pattern ion implantation conditions showed a doping concentration of 9.0E13 and an energy of 120 keV. The p-ion implantation conditions were optimized at a doping concentration of 6.5E13 and an energy of 80 keV, and the p+ ion implantation conditions were optimized at a doping concentration of 3.0E15 and an energy of 160 keV.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.4
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• pp.339-344
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• 1986

Frost damage which can reduce yields, impair fruit quality and cause loss of trees is closely related to the occurrence of daily minimum temperature. Horizontal distribution of air temperature minima can be characterized by conditions of radiational cooling and gravitational movement of cold air, which are influenced by the regional topographic features. Observations were made on the air temperature minima over Yangpyeong area, to delineate potential effects of topography on the temperature pattern during spring season. Two routes were selected for the observation. Liquid glass minimum thermometers were installed at 17 sites through the old peach orchards which had been closed due to the frequent freeze-frost hazards during the recent years. This route was 8.5km long and the highest point was 350m above mean sea level. The other route, which was 2.5km in distance, was run with a digital resistance thermometer during the hour just before sunrise. Observations were made both on a calm-clear day (April 30, 1986) and a windy-overcast day (May 1, 1986). The temperature on April 30 was in increasing trend with elevation but this was modified at near the riverside and the downtown area. An orchard lying on a hilltop showed the temperature $1^{\circ}C$ higher than near by lowland of which elevation was about 30m lower. The minimum temperature on the overcast day was little affected by terrestrial conditions but by the atmospheric lapse condition. The peach orchards severely damaged by cold air were found in the area where the lowest minimum temperature was observed. The results may be useful for selection of the proper orchard location to be developed in an area.

• The korean journal of orthodontics
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• v.32 no.6 s.95
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• pp.455-466
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• 2002

The objective of this study was to evaluate the changes that occurred over time in the distracted periodontal ligament space following the rapid retraction of a tooth by periodontal distraction after bone undermining surgery had been conducted in the dogs. The upper second premolars were extracted on the left and right side in 4 male beagle dogs. Immediately after extraction, the interseptal bone distal to the upper first premolar was thinned and undermined by grooving to decrease the bone resistance. Activating an individualized distraction appliance at the rate of 0.225mm twice a day, the upper first premolar was retracted rapidly toward the extraction socket. Periodontal distractions were performed for 5, 10, and 20 days, and 20-day-distraction cases were followed by maintenance periods of 0, 14, 28, and 56 days. After 20 days of rapid retraction, the average distal movement of the upper first premolar was 5.02mm, and the average mesial movement of the upper third premolars serving as an anchorage unit was 0.18 mm. On histological examination, the regeneration of bone occurred in a highly organized pattern. Distracted periodontal ligament space was filled with newly formed bone oriented in the direction of the distraction, and this was followed by extensive bone remodeling. This result was similar to those observed in other bones after distraction osteogenesis. In the periodontal ligament, the relationship between collagen fibers and cementum began to be restored 2 weeks after the distraction was completed, and showed almost normal features 8weeks after the completion of the periodontal distraction. However, on the alveolar side, the new bone formation was still in process and collagen fiber bundles and Sharpey's fibers were not present 8 weeks after the completion of the periodontal distraction. Reactions in the periodontal ligament of the anchorage tooth represented bone resorption on the compressed side and new bone deposition on the tension side as occurred in conventional orthodontic tooth movement. In conclusion, the results of this study showed that periodontal structures on the distracted side of the periodontal ligament were regenerated well histologically following rapid tooth movement.