• Clean Technology
• /
• v.7 no.1
• /
• pp.51-63
• /
• 2001

In this study, PSA, known as the most economic process, was used to recover $CO_2$ from the power-plant flue gas. Activated carbon and zeolite molecular sieve 13X were used as adsorbent. Activated carbon has been deemed inadequated adsorbent for separating $CO_2$ from the flue gas. However, highly concentrated $CO_2$ could be obtained as a product on the activated carbon adsorbent using the new operating cycle modifying the rinse step. Also, the recovery of $CO_2$ was improved using double-layered adsorption column packed with the activated carbon and the zeolite 13X simultaneously. Adsorption column was filled with the activated carbon in the feed-end side, and the zeolite 13X in the product-end side. The recovery of $CO_2$ increased about 40% with only 25% zeolite, and increased 67% with 50% zeolite at the experimental conditions of 13% $CO_2$ concentration, 10 SLPM flow rate and 2.2 atm adsorption pressure.

• Journal of agricultural medicine and community health
• /
• v.35 no.4
• /
• pp.361-369
• /
• 2010

Objectives: An outbreak of norovirus occurred at a high school in Gyeongju city in 2009. An epidemiological investigation was carried out to examine the infection source and the transmission route of norovirus, and to prevent a recurrence. Methods: A questionnaire survey was conducted for 520 male students and 8 food handlers. Rectal swabs were examined in 21 symptomatic students and the 8 food handlers by Gyeongsangbukdo Government Public Institute of Health & Environment, and an environmental investigation was performed. A case-control study was used to evaluate the association between risk factors and disease. Results: The attack rate was 21.3% (111/520) between January 29 and February 10, and norovirus GII was isolated from 12 of 21 students. Food handlers had no symptoms and their stool samples were negative. The case-control study revealed that seasoned soy bean sprouts {odds ratio (OR): 2.542, 95% CI=1.315-4.915} and drinking water from the purifiers in the cafeteria (OR: 2.854, 95% CI=1.107-7.358) supplied on February 3 were significant risk factors for the outbreak. Water pipes and waste pipes were located in the same place where was filled with some water and trace of high water level was detected. Conclusions: The major risk factors for this norovirus outbreak were presumed to be the contaminated seasoned soy bean sprouts and drinking water from the purifiers in the cafeteria. More strict personal and environmental hygiene need to be enforced to prevent such outbreaks.

• Journal of the Korean Geosynthetics Society
• /
• v.14 no.4
• /
• pp.79-86
• /
• 2015

Korean territories has formed about 70% of mountainous areas that have acidified serious level to average pH 4-5. There are a number of abandoned metal mines about 1,000 in Korea. However, mine tailings and waste rock included heavy metals are exposed to long-term environment without prevention facility or treatment system. Thus, ongoing management and monitoring of soil environment are required. Most of abandoned mine scattered in forest areas of slopes. Soil erosion due to continuous rainfall in the slopy areas can cause the secondary pollution by the influence eutrophication of water system and the productivity loss of the plant. Therefore, this study would like to estimate pH leaching rate by artificial rainfall using waste neutralization-agent in lysimeter. Moreover, the potentially of secondary pollution related to precipitation is figured out through the experiments, and the optimal planting methods would examinate after neutralizing treatment in soil. Experiments composed three kinds of lysimeter; lysimeter 1 had filled only acidic soil, lysimeter 2 had neutralized soil, and lysimeter 3 had planting plants after neutralized soil. In the results, lysimeter 2 showed the lowest pH leaching, and there is not specific relativity with pH leaching of the seasonal characteristics.

• Journal of Soil and Groundwater Environment
• /
• v.10 no.5
• /
• pp.37-44
• /
• 2005

The main object of this study is to develop the infiltration facility that it can be used in grounds, parking areas, roads, pathway, housing etc. As a result, it is much alike in the infiltration method of facility to use permeable concrete, permeable hole and be filled with broken stones. And through this experiment, it was perceived the truth that the state of ground, the groundwater level, buildings around them, the history of submerging and the applicable infiltration facilities are the key. To verify how much the infiltration facility reduce the outflow, we set up the infiltration facility in the test area. In result, it reduced the outflow 89% in 24 mm rainfall, 93% in 12 mm, 51% in 140 mm, 75% in 64 mm and 80% in 54 mm. As the rainfall rate increased, the infiltration increased up to the limited rainfall. And in the limited rainfall, we knew that the infiltration was reduced suddenly. Infiltration is closely related to the state of ground, the rain interval etc. and we will analyze these conditions through the continuous monitoring.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.49 no.3
• /
• pp.243-250
• /
• 2004

Two cultivars which are glutinous (Hawcheongchalbyeo) and non-glutinous (Hawcheongbyeo) near isogenic line of rice, were used for this study. The objective of this experiment was to gain the basic information for increasing grain yield of waxy rice by means of source and sink size control. In both Hwacheongbyeo and Hawcheongchalbyeo, the trend of decrease in total and average spikelet weight was ranked as follows; removal of penultimate leaf＜ removal of flag leaf＜ removal of flag leaf and 3ya leaf from the top ＜ removal of flag leaf and penultimate leaf ＜ removal of flag leaf, penultimate leaf, and 3rd leaf from the top. The reduction yale of total and average spikelet weight per panicle of Hwacheongbyeo was higher than those of Hwacheongchalbyeo according to the removal of flag leaf, penultimate leaf, and 3rd leaf from the top. In both cultivars, high-density grain ratio and grain filling ratio of the primary branches were higher Hun those of the secondary branches by leaf clipping treatment. The spikelet number and total spikelet weight per pinicle in both Hwacheongbyeo and Hwacheongchalbyeo were decreased by removal of spikelets on branches compared with control, whereas average spikelet weight and grain filling ratio were increased. The increase rate of average spikelet weight of Hwacheongchalbyeo was much higher than that of Hwacheongbyeo by sink size control. High-density grain ratio by removal of spikelets on branches was higher in Hwacheongchalbyeo, but filled grain ratio was higher in Hwacheongbyeo.

• Journal of Periodontal and Implant Science
• /
• v.26 no.3
• /
• pp.735-751
• /
• 1996

An ultimate goal of periodontal therapy is to stop the disease process and to regenerate a functionally-oriented periodontium destroyed as a result of periodontal disease. The purpose of this study was to observe the effect of grafting granulation tissue obtained from extraction socket on the regeneration of horizontal furcation defect. Six dogs were used in this study. All mandibular first and third premolars were extracted. At 2, 3, and 5 days after extraction, tissues were obtained from extraction socket of 1 mongrel dog and examined by light microscope. Granulation tissue obtained at 5 days after extraction was chosen as the graft material. Five days later, horizontal furcation defects were created surgically at mandibular second and fourth premolars in the right and left side of the 5 beagle dogs. The entrance area of the artificially prepared "key hole" defects were about $3\;4mm^2$. By random selections, 2 exposed furcation defects were grafted with granulation tissue obtained from extraction socket as experimental group and 1 furcation defect was as control. The flaps were replaced to their original position and sutured with 4-0 chromic cat-gut. Three dogs were sacrificed 4 weeks and two dogs 8 weeks after surgery, and the prepared specimens were examined by light microscope. At 4 weeks, furcations were filled with epithelial lining and fibrous connective tissue infiltrated with chronic inflammatory cells. New bone formation was observed in all groups. Only experimental group showed new cementum formation. At 8 weeks, new cementum, functional arrangement of new PDL fiber, root resorption, and some ankylotic union of newly formed alveolar bone and root surface were observed in all groups. Experimental group showed that epithelial downgrowth was inhibited and new bone formation was more active compared to control. The success rate of the furcation defect healing was higher in experimental group than control. These results suggested that grafting of granulation tissue obtained from extraction socket which combined with reconstructive periodontal flap surgery may promote periodontal regeneration of horizontal furcation defect.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.37 no.2
• /
• pp.179-185
• /
• 2010

Molar Incisor Hypomineralization(MIH) have recently gained intensive research interests and various clinical trials. Most prevalence, etiology, treatment studies in MIH were carried out in the European countries, and data from the Korean were seldom. This study aimed to investigate the prevalence of MIH and the status of dental caries and treatment on the first permanent molars in primary school children. For this study, 1,344 primary school students in Busan and Ulsan cities were examined directly the permanent incisors and first molars. The results of the survey were as follows: 81 MIH cases were identified among 1,344 cases. The prevalence of MIH in this group of children was 6.0%. Children with MIH showed a significantly higher DMFT value for permanent teeth than children without MIH. The mean number of decayed, missed, and filled in 1st permanent molars(DMFT index) was 1.17. The rate of children with restoration on 1st permanent molar was 13.6% and the sequence of restoration materials was as follows : composite resin, amalgam, gold inlay.

• Journal of Korean Society of Forest Science
• /
• v.102 no.4
• /
• pp.530-536
• /
• 2013

This study aimed to analyze and compare results from psychological relaxations by using profile of mood state (POMS) and Malondialdehyde (MDA) level as a scale of oxidative damage before and after walking in the forest and on the street. 29 participations (15 men and 14 women) walked in the forest and on the street for 30 minutes of each for two days. The participations filled a questionnaire for POMS and conducted an heart rate variability test, oxidative damage test (MDA as biological marker through a urine test) before and after walking. To compare the psychological states after walking in the two difference places, walking in the forest showed statistically more meaningful results in the section of tension, depression, anger, fatigue, confuse and total mood disturbance (p<0.01) than walking on the street. According to the MDA results, a concentration of MDA showed significant increase after walking on the street (p=0.014). On the contrary to this, a concentration of MDA tended to decrease after walking in the forest (p=0.076). The study showed that the psychological states were more stable and oxidative damages were more decreasing after walking in the forest than walking on the street. In the conclusion, MDA would be biological indicator for assessing the effect of alleviation on the oxidative stress after walking in the forest.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.45 no.3
• /
• pp.190-194
• /
• 2000

Double cropping is important for increase of farm income and rate of arable land utilization. This study was carried out to obtain information for optimum plant density of the second crop in a double cropping system. A waxy corn hybrid, Chalok #2, was sown on July 10 at the first corn cropping site. Growth characteristics and yield response of fresh waxy corn were examined under different planting densities, which were 55.5, 66.6, 83.3, and 111.1 thousands plants ${ha}^{-1}$. Plant height was higher under high planting density than low planting density and 154cm at the 55.5 thousand plants ${ha}^{-1}$, and 168cm at the 111.1 thousand plant ${ha}^{-1}$. It showed same trends in ear height and gravity center height. But planting density did not affect root lodging and silking date. At the silking stage, stalk and leaf dry matter weight and leaf area index (LAI) were increased significantly with increasing planting density, Filled ear lengtg was shortened significantly under the hi임est planting density (111.1 thousand plants ${ha}^{-1}$), while ear length and ear diameter were no differences among planting densities. The number of marketable ears increased with increasing planting density, but husked fresh ear weight was the highest at 83.3 thousand plants ${ha}^{-1}$ with 11.2MT ${ha}^{-1}$and optimum planting density was estimated as about 80 thousand plants ${ha}^{-1}$.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.16 no.4
• /
• pp.334-345
• /
• 2006

The objectives of this study were to analyze and compare 24 hrs personal exposure levels of MF at microenvironments such as home, school, educational institute, internet pc game room, transportation, and other places according to time activity patterns using various metrics for children attending the primary schools located near and away from the power lines, and to characterize the major microenvironments and impact factors attributed personal exposure level. The study was carried out for 44 children attending a primary school away from the lines(school A) and 125 children attending a school away from 154 kV power lines(school B), all who aged 12 years and were 6 grade, from July 2003 to December 2003. All participants filled in a questionnaire about characteristics, residence, use of electrical appliances and others. Children wore a small satchel in which EMDEX II and Lite (Enertech, Co. Ltd) and a diary of activity list for period of registration in 20 minutes blocks. All statistical calculations were made with the SAS System, Releas 6.12. The summary of results was presented below. First, about the characteristics of subjects, there no differences between two groups. The subject almost spent about 56 % of their time at home and about 20~25 % of their time at school. Fifty percent of children spent 2 hours at private educational institutes. Second, the personal exposure measurements of children in school B was statistically higher than those of children in school A by various metrics such as arithmetic mean, geometric mean, percentile(5, 25, 50, 75, 95), maximum, rate of change metric, constant field metric. The arithmetic and geometric mean magnetic fields during the time the children were at school B were 0.98 and $0.86{\mu}T$ and were about 23 times higher than those of children were at school A. In conclusion, the significant major determinants of personal exposure level is the distance from the power line to microenvironments.