• Journal of the Korean Society of Environmental Restoration Technology
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• v.5 no.4
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• pp.1-9
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• 2002

This study is carried out to make the environmentally affinitive porous planting block for revegetation and to make a effective program for greening plans. The summary is shown below. 1. In order to get stronger intensity and distribute proper porosity in the block for planting, the cements mixed with fine soil were used and the finer in soil grains gives the stronger in intensity of the cements. Use of the furnace slag cements instead of the portland cements showed relatively stronger in intensity of the block. The intensity of the block became stronger when the mixed ratio of the cements to soil is 5 : 1, but the pore space ratio was lower. The percolate pH of the portland cements after one month of treatment was 13.1 but the percolate pH of the furnace slag cements was shown lower. To mold proper porous planting blocks, the proper combination of additives such as the dehydrating agent, elastic agent and adhesives into the mixture of cements and soil gives better effectives. 2. After molding the porous planting blocks, it gave a better result when the grains of the filler made of peat moss, upland soil and compound fertilizer were smaller than 2 mm in size. Shaking of the filling materials also gave the better result, but it took more time and cost much more. Therefore, it was better when the filling materials were mixed with water first then flew down for stuffing. 3. It was necessary to cover with soil after seeding or planting on the porous planting blocks. The proper thickness of the soil to help root development and keep moisture is about 3~5 cm. 4. The plants for planting on the porous planting block were required stronger in the growth condition of their roots and their environmental adaptability. The average germination percentage and rate of Platycodon grandiflorum on the porous planting block were 88.8% and 85% accordingly and their rate is very uniform. The germination rates of Dianthus superbus var. longicalycinus and Taraxacum officinale were more than 50%. These grass species, Chelidonium majus var. asiaticum, Lysimachia mauritiana and Scabiosa mansenensis were the suggested biennial grasses in the planting area where exchanging of the seedling or nursery plants was not necessary because their germination rates were 59.3, 45.6 and 40.3% accordingly. Viola kapsanensis, Chrysanthemum sp., Taraxacum sp. and Iris ensata var. spontanea are the grass species that could be used by seeding for greening. However, the germination rate of Solidago virga-aurea var. asiatica, Aster scaber and Lythrum anceps were lower than 10%. The coverage ratio of Ixeris stolonifera is more than 80% after 60 days seeding and the root length of most of species are more than 10 cm except Iris ensata var. spontanea and Platycodon grandiflorum because their root developed thicker than other species.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.331-336
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• 2001

Theoretical approach was taken to the whole CNG refueling process. In particular, this study was focused on the prediction of flow rate at any given piping configuration of CNG system, in order that a simulation program for the CNG refueling system should be developed. The simulation result of refueling process was compared with experimental result obtained from various kinds of fueling configuration. The simulation results showed a satisfactory agreement within 10% errors in fueling time, fueling amount, and residual pressure. The developed program would be used a good engineering tools for estimating fueling performance for a any given CNG station.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.551-554
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• 2006

Inhibition of propellant temperature rising in liquid propulsion rocket using cryogenic fluid as a propellant is very important. Especially propellant temperature rising during stand-by after filling and pre-pressurization can bring into cavitation in turbo-pump. One of the method preventing propellant temperature rising in cryogenic feeding system is recirculating propellant through the loop composed of propellant tank, feed pipe, and recirculation pipe. The circulation of propellant is promoted through gas-lift effect by gas injection to lower position of recirculation pipe. In this experiment liquid oxygen and gas helium is used as propellant and injection gas. Under atmospheric and pressurized tank ullage condition, helium injection flow-rate is varied to observe the variation of recirculating flow-rate and propellant temperature in the feed pipe. There is appropriate helium injection flow-rate for gas-lift recirculation system.

• Journal of the Korean Society of Tobacco Science
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• v.21 no.2
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• pp.144-151
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• 1999

This study was carried out to compare the change physico-chemical properties in the 10 grades of Burley leaf tobacco expanded by $CO_2$. The filling capacity of AB3T was increased from 5.44cc/g to 9.52cc/g with the expansion rate 75.0% and that of CD3W was increased from 5.57cc/g to 10.16cc/g with the expansion rate 82.4%. But the rate of cut tobacco longer than 3.36 mm decreased from 77.2% to 49.9% and from 67.3% to 41.2% in grade B1T and C1W, respectively. The contents of nicotine and total volatile base in the of expanded cut tobacco decreased 11.9% and 10.4% respectively. The contents of onganic acids, except oxalic and palmitic acid, essential oil, amino acids, nicotine, tar and ammonia contents in the cigarette smoke decreased by expansion procecs. These results suggest that expanded tobacco was very useful to make less irritative cigarettes.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.333-338
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• 2003

Although porous concrete is resently used as a pavement at a parking lot, a public squre and a bicycle road, we use without enough examining. most the maintenance of quality for porous concrete is only dealt with strength and color tone. also, there is not yet enough fundamental data about dynamical properties for strength, rate of void and water permeability. even when it is applied to at the scene, it is been a matter. Accodingly in this study analyzed influences through the dynamical properties, combination, and time to vibration. After the analyzation, they investigated peculiar dynamics which are strength of porous concrete, rate of void, and water permeability follow the rate of increase on an admixture making pozzolan reaction. This is purpose to improve capacity of the sidewalk permeable concrete and development of the economical technique for pavement.

• Journal of the Korean Society of Tobacco Science
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• v.7 no.2
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• pp.189-197
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• 1985

The purpose of this study is to improve the method and the apparatus for recovering freon-11 used in a process for increasing the filling capacity of tobacco. The first, the theoretical recovery rate of freon-11 was calculated from vapour pressure and thermodynamic properties of freon-11. The second, the usability of theoretical data was evaluated by the comparison between the theoretical data and the experimental data from the pilot plant. The result obtained under the present experiment condition was quite similar to the rate at 15kg/cm2 and 5$^{\circ}C$, but the theoretical data evaluated were 0.1 to 0.3% lower than the experimental data at 20 to 25kg/cm2 and 5$^{\circ}C$. The recovery rate of the cooling and the compression system was about 95% with freon-11 used in this system and that with freon-11 concentrate of waste gas was about 3 to 3.6% at 20 to 25kg/cm2 and 5$^{\circ}C$.

• Journal of Industrial Technology
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• v.18
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• pp.1-6
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• 1998

This study was conducted to use disused vinyl as biofilm for biological sewage treatment. Efficiency verification was performed on laboratory and on-site plant. In laboratory study, total biochemical oxygen demand(TBOD) removal rate was ranged 94.8~97 % in each hydraulic retention tim(HRT), 12, 16, 20, 24 hr, respectively. At that time, filling rate was 50 %. And effluent TBOD concentration was low ranged 3.64~6.28 mg/L. In on-site plant, TBOD removal rate was ranged 88.2~96.8 % and effluent TBOD concentration was 4.8~17.7mg/L. This concentration was lower than disign effluent concentration, 30mg/L. Total kjeldhal nitrogen(TKN) removal efficiency was ranged 56.8~90.9%. This was resulted higher than Lab. scale treatment efficiency.

• Journal of the korean academy of Pediatric Dentistry
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• v.11 no.1
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• pp.181-189
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• 1984

1,840 school children aged 6 to 13 years who live in inland area in CHOONG CHUNG BUK DO were surveyed epidemiologically on the dental caries prevalence. The results were as follows; 1. The prevalence of dental carries was 76.35 percentage in male, 76.15 percentage in female, and 76.25 percentage in both sexes. 2. d.m.f rate was 77.72 percentage in male, 80.07 percentage in female, and 78.86 percentage in both sexes. D.M.F rate was 30.73 percentage in male, 38.52 percentage in female, and 34.51 percentage in both sexes. 3. d.m.f.t. rate and index was 27.94 percentage,2.55T, and d.m.f.s. rate & index was 13.62 percentage, 6.22T. 4. D.M.F.T rate & index in permanent teeth was 4.86 percentage,0.72T, and D.M.F.S. rate & index was 1.20 percentage,0.89T. 5. The filling rate was 3.90 percentage in decidious teeth, 2,00 percentage in permanent teeth.

• Journal of Korean Dental Science
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• v.14 no.2
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• pp.61-68
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• 2021

Purpose: The aim of this study was to investigate the outcomes of endodontic treatment of mandibular second molar with C-shaped canal in elderly patients and related factors affecting the survival of the tooth. Materials and Methods: From 2010 to 2015, the survival rate following endodontic treatment was evaluated in elderly patients over 60 years who visited the Veterans Health Service Medical Center for endodontic treatment. The presence of C-shaped canals was confirmed using clinical records and radiographic features. Patient's age, sex, systemic diseases, tooth location, vitality, signs and symptoms, fractures, caries, apical radiolucency, canal shaping methods, sealer leakage, filling voids, and restoration of prosthesis were included in the analyses as confounding variables. The survival rate of teeth was analyzed using Kaplan-Meire analysis and the relationship between the survival rate and variables was analyzed using Simple and Multiple Cox regression analysis. Result: In total, 107 teeth in elderly patients had C-shaped canal. The survival rate of teeth that received endodontic treatment was 63.70%. None of the factors investigated significantly influenced the survival rate (P>0.05). Conclusion: In elderly patients with C-shaped canal, the survival rate after root canal treatment was not significantly different from that of other mandibular molars.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.288-291
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• 2003

The technology and performance of the world-largest 54-inch LCD TV using PVA mode have been introduced from two points of view: one is to manufacture large-size panels, the other is to improve electro-optical performance required for multimedia applications. Current ongoing research activities that have been explored include new stitching design, one drop filling with column spacer, response time less than one frame rate, color performance and light efficiency enhancement.