• Restorative Dentistry and Endodontics
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• v.34 no.6
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• pp.526-536
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• 2009

The aim of this vitro-study is to evaluate the effects of fluoride on remineralization of artificial dentine caries. 10 sound permanent premolars, which were extracted for orthodontic reason within 1 week. were used for this study. Artificial dentine caries was created by using a partially saturated buffer solution for 2 days with grounded thin specimens and fractured whole-body specimens. Remineralization solutions with three different fluoride concentration (1 ppm. 2 ppm and 4 ppm) were used on demineralized-specimens for 7 days. Polarizing microscope and scanning electron microscope were used for the evaluation of the mineral distribution profile and morphology of crystallites of hydroxyapatite. The results were as follows: 1. When treated with the fluoride solutions, the demineralized dentine specimens showed remineralization of the upper part and demineralization of the lower part of the lesion body simultaneously. 2. As the concentration of fluoride increased, the mineral precipitation in the caries dentine increased. The mineral precipitation mainly occurred in the surface layer in 1 and 2 ppm- specimens and in the whole lesion body in 4 ppm -specimens. 3. When treated with the fluoride solution, the hydroxyapatite crystals grew. This crystal growth was even observed in the lower part of the lesion body which had shown the loss of mineral.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2003.11a
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• pp.97-98
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• 2003

This experiment was conducted to investigate the effect of restricted feeding to pullet on growth and laying Performance, egg qualify and endocrine Profile in brown layers. 1,080 brown-layer chicks divided to three diet treatments, conventional diet and two restricted diets, for 70 weeks. Conventional diets(C) was formulated by NRC recommendation, and one of restricted diet started from seven to seventeen week of age(T1), and another started from twelve to seventeen(T2) with adjusted eighty percentage amount of conventional diet. Body weight decreased with starting restriction of feeding comparing to the C(P＜0.05), but reached to similar weight in all treatments at twenty week regardless restriction. All of birds started to lay egg around 1,400 to 1,450gram of body weight though the age was in order of C, T2 and T1. Overall e99 Production was the highest in T1 (P＜0.05) and there were not difference in C and T2. Average egg weight also showed similar to the tendency of egg production. Feed intake was higher in T1 during maximum production(P＜0.05), but there were not difference in all treatments after the peak. Overall feed conversion ratio improved in T1 compared to C and T1(p＜0.05). Restriction feeding in rearing period could be beneficial to improve egg productivity and to decrease feed cost.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.2
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• pp.98-104
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• 2001

Cultivation area of the plastic film-house has been continuously increased with the increase of consumers' income. Intensive land use without fallowing or crop rotation caused severe problem such as salt accumulation in soils and in turn retarded growth and low productivity. This study was carried out to solve them derived from longterm intensive farming practices. Seven farmers who are practicing plastic film-house cultivation were recommended for case study by municipal government and selected for their excellency of cultivation and soil management. The cultivation periods of these systems were in the range of 5 to 40 years in the regions mainly located in alluvial soil cultivated with cucumber, tomato and red pepper. The soils texture of the excellent farmers' fields were silt loam or sandy loam, ranged from 7 to 15 percents of clay contents. Soil bulk density, depth of plowing layer and soil aggregates contents of the farmers' soils were 0.89, 23.1 cm, 61.6% whereas those in neighboring soils were 1.10, 17.8 cm, 54.2 %, respectively. And pH, OM and $NO_3-N$ of the farmers' soils also were better than those of neighboring soils. There was no difference in population densities of nematode between the good farmers' and neighboring soils, but actinomyces and Fusarium densities of recommended farmers' soils were better than neighboring soils. The major farming practices by the good farmers were characterized by deep plowing with flooding, amendment of crude organic matter, and reduction of chemical fertilizer application before transplanting, and also drip irrigation and liquid manure application after planting. They also conducted solar sterilization with or without flooding, removal of plastic films during rainy days and culturing rice or corn as rotation crops to avoid the problems mentioned above.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.74-74
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• 2010

One-dimensional nanosturctures such as nanowires and nanotube have been mainly proposed as important components of nano-electronic devices and are expected to play an integral part in design and construction of these devices. Silicon carbide(SiC) is one of a promising wide bandgap semiconductor that exhibits extraordinary properties, such as higher thermal conductivity, mechanical and chemical stability than silicon. Therefore, the synthesis of SiC-based nanowires(NWs) open a possibility for developing a potential application in nano-electronic devices which have to work under harsh environment. In this study, one-dimensional nanowires(NWs) of cubic phase silicon carbide($\beta$-SiC) were efficiently produced by thermal chemical vapor deposition(T-CVD) synthesis of mixtures containing Si powders and hydrocarbon in a alumina boat about $T\;=\;1400^{\circ}C$ SEM images are shown that the temperature below $1300^{\circ}C$ is not enough to synthesis the SiC NWs due to insufficient thermal energy for melting of Si Powder and decomposition of methane gas. However, the SiC NWs are produced over $1300^{\circ}C$ and the most efficient temperature for growth of SiC NWs is about $1400^{\circ}C$ with an average diameter range between 50 ~ 150 nm. Raman spectra revealed the crystal form of the synthesized SiC NWs is a cubic phase. Two distinct peaks at 795 and $970\;cm^{-1}$ over $1400^{\circ}C$ represent the TO and LO mode of the bulk $\beta$-SiC, respectively. In XRD spectra, this result was also verified with the strongest (111) peaks at $2{\theta}=35.7^{\circ}$, which is very close to (111) plane peak position of 3C-SiC over $1400 ^{\circ}C$ TEM images are represented to two typical $\beta$-SiC NWs structures. One is shown the defect-free $\beta$-SiC nanowire with a (111) interplane distance with 0.25 nm, and the other is the stacking-faulted $\beta$-SiC nanowire. Two SiC nanowires are covered with $SiO_2$ layer with a thickness of less 2 nm. Moreover, by changing the flow rate of methane gas, the 300 sccm is the optimal condition for synthesis of a large amount of $\beta$-SiC NWs.

• Journal of Wetlands Research
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• v.20 no.3
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• pp.235-242
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• 2018

The function of vertical subsurface flow wetlands can potentially be reduced with time due to clogging and are often assumed to be occurring when ponding and overflow is observed during rainfall. To investigate their clogging potential, three pilot-scale vertical subsurface flow (VSF) wetland systems were constructed employing woodchip, pumice, and volcanic gravel as main media. The systems received stormwater runoff from a highway bridge for seven months, after which the media were taken out and divided into layers to determine the amount and characteristics of the accumulated clogging matters. Findings revealed that the main clogging mechanism was the deposition of suspended solids. This is followed by the growth of biofilm in the media which is more evident in the wetland employing woodchip. Up to more than 30% of the clogging matter were found in the upper 20 cm of the media suggesting that this layer will need replacement once clogging occurs. Moreover, no signs of clogging were observed in all the wetlands during the operation period even though an estimation of at least 2 months without clogging was calculated. This was attributed to the intermittent loading mode of operation that gave way for the decomposition of organic matters during the resting period and potentially restored the pore volume.

• Horticultural Science & Technology
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• v.28 no.3
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• pp.381-386
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• 2010

The berry growth and pericarp characteristics were characterized to confirm the effects of bagging periods on berry cracking during berry development in 'Kyoho' grape. The berry weight was the highest at 13.4 g in late period of bagging treated at 7 to 9 weeks after full bloom (WAFB) as compared with the lowest of 12.3 g in total period bagging. The berry cracking rate under critical turgor pressure in the non-bagging control was 53.3%, while those of bagging treatments were decreased in the order of 42.7%, 37.3%, 33.3%, and 18.7% in bagged during 3 to 9, 3 to 5, 5 to 7, and 7 to 9 WAFB, respectively. In the results of observation on histological characteristics of pericarp, berry lenticels of whole bagging treatments had smaller and normal shape compared with non-bagging control treatment. Especially on the pericarp of late period bagged during 7 to 9 WAFB, suberization around stomata and micro-cracking were not observed and structural strength of pericarp was increased with thicker sub-epidermal layer and cell wall. Therefore, the results indicate that bagging treatment for two weeks just before the veraison when the day length and daylight is relatively longer and stronger can effectively reduce berry cracking by strengthening structure of pericarp in 'Kyoho' grape.

• Food Science of Animal Resources
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• v.27 no.4
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• pp.401-408
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• 2007

This study examined the histochemical and physiological characteristics during Korean native Ogol chickens (KNOC) development. The body weight, Pectoralis major and soleus muscle weights, and muscle samples were taken at hatching as well as at 3, 5, and 15 weeks of age. The fiber characteristics of the Pectoralis major and soleus muscles from the KNOC at hatching to 15 weeks of age were determined, and the deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein concentrations were measured from the left Pectoralis major muscles. A greater increase in body and muscle weights was detected between hatching and 3 weeks of age than during any other period. Moreover, the cross sectional area (CSA) of the fibers, as well as the total concentration of DNA, RNA, and protein also showed a greater increase betweenhatching and 3 weeks of age than during any other period. The KNOC breed is a dual purpose breed, however, the it has lower body and muscle weights than commercial meat type chickens or layer type chickens. Moreover, the KNOC breed has a small muscle fiber CSA of and a low nucleic acid concentration.

• Fire Science and Engineering
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• v.31 no.5
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• pp.28-36
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• 2017

In this work, the effects of fire curtain and forced smoke ventilation on smoke spread to auditorium in the stage fire of theater were investigated using the Fire Dynamics Simulator (FDS). For the stage of 31 m (Width)${\times}$34 m (Depth)${\times}$32 m (Height) in dimension, the fast growth fire condition with 10 MW of heat release rate was applied. The forced smoke ventilation was set based on the National Fire Safety Code (NFSC) and previous research. The gap distances between the fire curtain and proscenium wall was established to be 0 m and 0.5 m. When the fire curtain was attached completely to the proscenium wall without any gap, no smoke spread from the stage to the auditorium occurred, independent of forced smoke ventilation. When the gap distance between the fire curtain and proscenium wall was 0.5 m, the smoke layer in the stage descended to the lower height from the bottom than the case without the fire curtain, which was because the smoke spread to auditorium was impeded by the fire curtain. Under the same fire curtain condition, the case with the forced smoke ventilation led to decreasing the mass flow rate of outflow through the gap between the fire curtain and proscenium wall, as compared to the case without the forced smoke ventilation. Based on this study, it was confirmed that the fire curtain and forced smoke ventilation were the effective tools to hold down the smoke spread to the auditorium in the stage fire of theater.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.1
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• pp.49-55
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• 2009

Our domestic economy has been developed very rapidly after 1960's. Also, it is dramatically increasing traffic on road and surround environmental issues. Especially, rapid economic growth has been induced large construction of pavement, and bigger and higher traffic for transportation. These are making air pollution, traffic noise and vibration. The social requirement against the revealed road environment and traffic sound reduction is being demanded. Traffic noise of city zone is showed over the environmental specification more than 57%. In order to overcome these situations, the social attention is being increased. The quiet pavement is the same format of permeable pavement, but is not same for functional performance. In this research, it has been carried out to evaluate the fundamental-mechanical properties of hot mix asphalt for quiet pavement. Especially, couple of laboratory tests are conducted like marshall stability, resilient modulus, indirect tensile test, and compaction energy analysis with gyratory compaction curve. Also, two-layer pavement system has been adopted for developing of quiet pavement. The basic performance of hot mix asphalt of quiet pavement show a satisfaction of specification of hot mix asphalt.

• Journal of Sericultural and Entomological Science
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• v.20 no.2
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• pp.20-25
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• 1978

Research on the hormones of insect has followed by the special opportunities and problems arising from pollution. Since then, the main frame of it has been energetically exploited by ligation, decapitation and so on. In the meanwhile, knowledge of the biochemistry of hormone action as well as other aspects of biochemistry in insects has been gradually disclosed. Since 1966, practical use of active analogs of the hormones has been also worked out as an insecticide and brought the features of it to the light. On the other hand, it is expected to afford the increase of silk productivity resulted from control of the fifth larval period by delaying normal development. With these regards, some of analogs have been tried to apply practically to the silkworm. One of them is "Manta" produced by Zoecon Chemical Company and it is presently used for the increase of silk productivity in Japan. Another one is "R-20458", not registered one, issued by Stuffer Chemical Company. It is still pending for the silkworm growth regulator For the possibility of practical use, two chemicals are tested on the increase of silk productivity by topical application and the obtained results are summarized as follows. 1. It is evident that the fifth larval period was extended by topical application of the tested chemicals "Manta"and "R-20458"at the fifth instar after 51 hours of the last ecdysis, ranging from 12 hours to one day, as compared to. the control 2. In survival rates, there is no significance at 5% level between control and treatments. It proved that there was no toxity to silkworm by topical aprication. 3. There is an increase of cocoon yield in both chemical treatments. It was resulted from increase of weight of single cocoon. "Manta"2.5ppm produced 22.2kg of cocoon. It is equal to 9% increase in index, as compared to that of control. In case of R-20458, the increasing rates were varied at the different concentration; 21.4kg of cocoon production with 5% increase at 5ppm, 20.9kg of it with 2% increase at 2.5ppm and 20.6kg of it with 1% increase at 1. 25ppm in index, respectively, as compared with that of control. 4. Percentage of cocoon shell was increased by topical application. In case of "Manta" 2.5ppm, it is 25.6% which is equal to 6% increase in index, as compared with that of control. For "R-20458", the increasing rates of percentage of cocoon shell were varied with the different level of chemical concentration. They are 25.0% of 4% increase at 2.5ppm, 24.9% of 3% increase at 1.25ppm and 24.7% of 3% increase at 5ppm. 15% increase was attained at "Manta" 2.5ppm in the weight of cocoon layer based on cocoon yield and percentage of cocoon shell in index, as compared with that of control. The rates for "R-20458"are 5% increase at 2.5ppm and 4% increase at 1. 25ppm in index.