• Restorative Dentistry and Endodontics
• /
• v.32 no.4
• /
• pp.343-355
• /
• 2007

The objectives of this study was to evaluate the durability of 4 resin cements by means of microtensile bond strength test combined with thermocycling method and fractographic FE-SEM analysis. Experimental groups were prepared according to thermocycling (0, 1,000, 5,000) and the kind of resin cements, those were Variolink II, Multilink, Panavia F 2.0, Rely X Unicem. Flat dentin surfaces were created on mid-coronal dentin of extracted third molars. Then fresh dentin surface was grounded with 320-grit silicon carbide abrasive papers to create uniform smear layers. Indirect composite block (Tescera, Bisco Inc., Schaumburg, IL, USA) was fabricated ($12\;{\times}\;12\;{\times}\;6\;mm^3$). It's surface for bonding to tooth was grounded with silicon carbide abrasive papers from 180- to 600-grit serially, then sandblasted witk $20\;-\;50\;{\mu}m$ alumina oxide. According to each manufacturer's instruction, dentin surface was treated and indirect composite block was luted on it using each resin cement. For Rely X Unicem, dentin surface was not treated. The bonded tooth-resin block were stored in distilled water at $37^{\circ}C$ for 24 hours. After thermocycling, the bonded tooth-resin block was sectioned occluso-gingivally to 1.0 mm thick serial slabs using all Isomet slow-speed saw (Isomet, Buehler Ltd, Lake Bluff, IL, USA). These sectioned slabs were further sectioned to $1.0\;{\times}\;1.0\;mm^2$ composite-dentin beams. The specimens were tested with universal testing machine (EZ-Test, Shimadzu, Japan) at a crosshead speed of 1.0 mm/min with maximum load of 500 N. The data was analyzed using one-way ANOVA and Duncan's multiple comparison test at $p\;{\leq}\;0.05$ level. Within the limited results, we conclude as follows; 1. The bond strength of Variolink II was evaluated the highest among experimental groups and was significantly decreased after 1,000 thermocycling (p < 0.05). 2. The bond strength of Multilink was more affected by thermocycling than the other experimental groups and significantly decreased after 1,000 thermocycling (p < 0.05). 3. Panavia F 2.0 and Rely X Unicem showed the gradually decreased tendency of microtensile bond strength according to thermocycling but there was no significant difference (p > 0.05). 4. Adhesive based-resin cements showed lower bond strength with or without thermocycling than composite based-resin cements. 5. Variolink II & Multilink showed high bond strength and mixed failure, which was occurred with a thin layer of luting resin cement before thermocycling and gradually increased adhesive failure along the dentin surface after thermocycling. The bonding performance of resin cement can be affected by application procedure and chemical composition. Composite based-resin cement showed higher bond strength and durability than adhesive based-resin cement.

• Land and Housing Review
• /
• v.2 no.4
• /
• pp.453-461
• /
• 2011

This study is to derive a project model based on potential demand for Korean-style houses, focusing on new town detached housing sites that LH supplies and to test validity of the derived model and to present the direction and supply methods of the projects. The existing high-class new town Korean-style housing developments that have been considered were found to have little business value due to problems in choice of location and discordance of demand, so 6 types of projects were established through the methods of changes in planned scale, combined use, and subdivision of plot of land based on the results of survey. The type that has the highest business value among the project models was block-type multifamily houses, and this can be interpreted as the increase in total construction area leading to increase inrevenues of allotment sales due to economies of scale. The feasibility of mass housing model in which small-scale Korean-style houses are combined with amenities was found to be high, and if the same project conditions as those of the block-type multifamily houses are applied, the business value of the Korean-style tenement houses was found to be high. Besides, the high-class housing models within block-type detached housing areas are typical projects that the private sector generally promotes, and the construction cost was found to be most expensive with 910 million won per house. In order to enhance the business value of the Korean-style housing development, collectivization such as choice of location, diversification of demand classes, optimization of house sizes, and combination of uses is needed. And in order to adopt Korean-style houses in the detached housing sites, the adjustments and division of the existing planned plots are needed, and the strategies to cope with new demand through supplying Korean-style housing types of sites can be suggested. Also breaking away from the existing uniform residential development methods, the development method through supplying original land that is natural land not yet developed besides basic infrastructures (main roads and water and sewage) can be considered, and as the construction of more than 1~2 stories building is impossible due to the structure of Korean-style house roof and furniture. So it can be suggested that original land in the form of hilly land is considered to be most suitable to large-scale development projects.

• Korean Journal of Soil Science and Fertilizer
• /
• v.36 no.5
• /
• pp.323-332
• /
• 2003

This study was carried out to provide information for the present status of soil pollution near abandoned old-zinc mining area through analysis of bound form and 0.1 N-HCl extractable concentrations of heavy metals in soils and plants. Feasibility of endemic plants for phytoremediation was evaluated by the investigation of vegetation in soils. Cd contents of the selected samples near old-zinc mining soils ranged from 0.2 to $42mg\;kg^{-1}$. Nonagricultural soils near the mining area contained great amounts of Zn, Pb, Cd, and Cu than the paddy and upland soils. Some Korean wild plants, Artemisia princeps, Artemisia montana, Erigeron canadensis, and Pueraria thunbergiana, were found to grow vigorously in the studied area. Among them, Artemisia princeps was selected as a possible phytoremediator for cleaning heavy metal contaminated soils. Artemisia princeps contained about 43 and $52mg\;kg^{-1}$ of Cd in their root and shoot as dry weight, respectively. Average contents of Cd in the rhizosphere soil, $15.68mg\;kg^{-1}$, was slightly higher than the soil-root interface soils, $14.1mg\;kg^{-1}$. Sequential extraction of Cd contaminated soils showed that average $2.4mg\;kg^{-1}$ (about 7%) of cadmium existed as exchangeable form and the average amounts increased as follows : adsorbed < organically bound < exchangeable << oxide carbonate << sulfide residual fractions. Amendment of organic by-product fertilizer in metal-contaminated soils promoted the growth of roots significantly as compared with the other treatments containing chemical fertilizer.

• Korean Journal of Weed Science
• /
• v.12 no.2
• /
• pp.144-157
• /
• 1992

The study was conducted to compare the interprete methods and examine the feasibility of mixture use of oxyfluorfen and bensulfuron in controlling principal Paddy weeds, annuals and perennials. Application ratio of both chemicals were obtained from the combinations of 5 levels(0, 5, 10, 15, 20 g ai/ha) of each chemicals, respectively. All the treatments were applied at 5 days after transplanting and water was maintained at 3.0cm in depth. Shoot fresh-weight of weeds was assessed at 35 days after treatments. Data obtained was analysed by Colby, Isobole, Calculus, Regression and EQM method, respectively. The results from the analysis of variance on the principal weeds treated with oxyfluorfen and bensulfuron showed significant interactions at 1% level on both Echinochloa crus-galli and Eleocharis Kuroguwai, and total species at 0.5% level on both Potamogeton distinctus and Cyperus serotinus, but non significant on Scirpus juncoides and Sagittaria pygmaea. Thereafter, the results of the models applied to Echinochloa crus-galli, Eleocharis kuroguwai and total species were as follows ; 1. The Colby method gave values nearly identical to regression estimate method (both multiplicative models) as provided by Akobundu et al. The Colby method and Regression method indicated synergistic toward Echinochloa curs-galli, and total species, but antagonistic toward Eleocharis kuroguwai. 2. The Isobole method shows synergism on Echinochloa crus-galli at $ID_{50}$, and total species at $ID_{60}$ on Eleochari kuroguwai. 3. The Calculus method gave positive signs for the first differentiation and negative signs for the second differentiation except for some rates on Echinochloa crus-galli and total species, but reverse on Eleocharis kuroguwai. These result does not agree with the observed values. 4. ${\theta}$ value from the EQM method was greater than one at all combinations. This result was quite different from those of other methods. 5. The various models did not show the same results, but mixture of oxyfluorfen and bensulfuron tend to have synergistic effect. Weeding effect also was high. Treatment in terms of two chemical combination was expected to reduce rates, and to enhence weeding efficacy compared with single treatment.

• Journal of the Mineralogical Society of Korea
• /
• v.20 no.4
• /
• pp.357-366
• /
• 2007

Microorganisms participate in a variety of geochemical processes such as weathering and formation of minerals, leaching of precious metals from minerals, and cycling of organic matter The objective of this study was to investigate biogeochemical processes of iron leaching from magnetite ore by iron-reducing bacteria isolated from intertidal flat sediments, southwestern part of Korea. Microbial iron leaching experiments were performed using magnetite ore, Shinyemi magnetite ore, in well-defined media with and without bacteria at room temperature for a month. Water soluble Fe and Mn during the leaching experiments were determined by ICP analysis of bioleached samples, and the resulting precipitated solids were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The extent of iron leaching from magnetite in the aerobic conditions (Fe = 15 mg/L and Mn = 3.41 mg/L) was lower than that in the anaerobic environments (Fe = 32.8 mg/L and Mn = 5.23 mg/L). The medium pH typically decreased from 8.3 to 7.2 during a month incubation. The Eh of the initial medium decreased from +144.9 mV to -331.7 mV in aerobic environments and from -2.3 mV to -494.6 mV in anaerobic environments upon incubation with the metal reducing microorganisms. The decrease in pH is due to glucose fermentation producing organic acids and $CO_2$. The ability of bacteria to leach soluble iron from crystalline magnetite could have significant implications for biogeochemical processes in sediments where Fe(III) in magnetite represents the largest pool of electron acceptor as well as to use as a novel biotechnology for leaching precious and heavy metals from raw materials.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.20 no.1
• /
• pp.163-170
• /
• 2006

Nardostachyos Rhizoma (N. Rhizoma) belonging to the family Valerianaceae has been anti-arrhythmic effect, and sedation to the central nerve and a smooth muscle. We reported that the water extract of N. Rhizoma induced apoptotic cell death and differentiation in human promyelocytic leukemia (HL-60) cells. Cytotoxicity of N. Rhizoma was detected only in HL-60 cells (IC50 is about 200 ${\mu}g/ml$). The cytotoxic activity of N. Rhizoma in HL-60 cells was increased in a dose-dependent manner. We used several measures of apoptosis to determine whether these processes were involved in N. Rhizoma-induced apoptotic cell death. The high-dose (200 ${\mu}g/ml$) treatment of N. Rhizoma to HL-60 cells showed cell shrinkage, cell membrane blobbing, apoptotic bodies, and the fragmentation of DNA, suggesting that these cells underwent apoptosis. Treatment of HL-60 cells with N. Rhizoma time-dependently induced activation of caspase-3, caspase-8, and caspase-9 and proteolytic cleavage of poly(ADP-ribose) polymerase. Also, we investigated the effect of N. Rhizoma on cellular differentiation and proliferation in HL-60 cells. Differentiation and proliferation of HL-60 cells was determined through expression of CD11b and CD14 surface antigens using flow cytometry and nitroblue tetrazolium (NBT) assay, and through analysis of cell cycle using propidium iodide assay, respectively. N. Rhizoma induced the differentiation of HL-60 at the low-dose (100 ${\mu}g/ml$) treatment, as shown by increased expression of differentiation surface antigen CD11b, but not CDl4 and increased reducing activity of NBT. When HL-60 cells were treated with N. Rhizoma at concentration of $50{\mu}g/ml\;and\;100{\mu}g/ml$, NBT-reducing activities induced approximately 1.5-fold and 20.0-fold as compared with the control. In contrast, HL-60 cells treated with the N. Rhizoma-ATRA combination showed markedly elevated levels of 26.3-fold at $50{\mu}g/ml$ N. Rhizoma-0.1 ${\mu}M$ ATRA combination and 27.5-fold at 50 ${\mu}g/ml$ N. Rhizoma-0.2 ${\mu}M$ ATRA combination than when treated with N. Rhizoma alone or ATRA alone. It may be that N. Rhizoma plays important roles in synergy with ATRA during differentiation of HL-60 cells. DNA flow-cytometry indicated that N. Rhizoma markedly induced a G1 phase arrest of HL-60 cells. N. Rhizoma-treated HL-60 cells increased the cell population in G1 phase from 32.71% to 42.26%, whereas cell population in G2/M and S phases decreased from 23.61% to 10.33% and from 37.78% to 33.98%, respectively. We examined the change in the $p21^{WAF1/Cip1}\;and\;p27^{Kip1}$ proteins, which are the CKIs related with the G1 phase arrest. The expression of the CDK inhibitor $p27^{Kip1},\;but\;not\;p21^{WAF1/Cip1}$ were markedly increased by N. Rhizoma. Taken together, these results demonstrated that N. Rhizoma induces apoptotic cell death through activation of caspase-3, and potently inhibits the proliferation of HL-60 cells via the G1 phase cell cycle arrest in association with $p27^{Kip1}$ and granulocytic differentiation induction .

• Parasites, Hosts and Diseases
• /
• v.29 no.3
• /
• pp.293-310
• /
• 1991

Clonorchis sinensis is a common parasite of man in Korea. Researches on the specific antigens of C. sinensis would be valuable not only because those elucidate the molecular characteristics of this fluke but also because it is applicable to immunodiagnosis. Although many monoclonal antibodies have been used in the field of parasite immunology, few articles on monoclonal antibodies against C. sinensis have been published so far. The aim of this study was to analyse C. sinensis antigens recognized by monoclonal antibodies, and to set up ELISA-inhibition test using C. sinensis specific monoclonal antibodies for improved specificity of immunodiagnostic tests. By fusion between spleen cells of the mice immunized with C. sinensis water-soluble crude adult worm antigens and plasmacytoma cells of mouse origin, 29 hybridoma clones secreting anti-C. sinensis monoclonal antibodies were made, and 8 clones among those were found specific. After cell cloning, isotypes of 6 selected specific monoclonal anti- bodies were determined to be IgGl, IgG2b and IgA. Four exposed antigenic determinants of natural infection were recognized by different specific monoclonal antibodies. By enzyme-immunoelectrotransfer blot, 10 KD, 34 KD antigenic determinants were found to be reacted with CsHyb 0714-20, CsHyb 0605-10 monoclonal antibodies, respectively, The antigenic determinant recognized by CsHyb 0714-20 monoclonal antibody was revealed to be located at the surface and parenchyme of a parasite by indirect immunoauorescent antibody technique, and those reacted with CsHyb 0605-10, CsHyb 0714-25 monoclonal antibodies were found at the parenchyme and intestine. The antigenic determinant reacted with CsHyb 0605-23 monoclonal antibody was found mainly around the uterine eggs. Four antigenic determinants recognized by specific monoclonal antibodies were all found to be present in the early eluted fractions of C. sinensis antigens separated by Sephadex G-200 gel filtration. By conventional ELISA, 75% of clonorchiasis cases were found positive, but 7.1% of normal controls and 37.5% of paragonimiasis cases showed false positives. However, by ELISA-inhibition test using C. sinensis specific monoclonal antibody (CsHyb 0605-23), 77.1% of clonorchiasis cases were found positive, and there were no false positives in normal controls or paragonimiasis cases, indicating 100% specificity. The ELISA- inhibition test using monoclonal antibodies was found to have same sensitivity and definitely high specificity in comparison with conventional ELISA for serodiagnosis of human clonorchiasis.

• Journal of Plant Biotechnology
• /
• v.37 no.4
• /
• pp.517-528
• /
• 2010

Rice seed maturation and germination involve drastic changes in water and nutrient transport, in which tonoplast aquaporins may play an important role. In the present study, gene expression profiles of 10 tonoplast intrinsic proteins (TIP) from rice were investigated by RT-PCR during seed development and germination. OsTIP3;1 and OsTIP3;2 were specifically expressed in mature seeds. Their transcript level rapidly decreased after onset of seed germination and gene expression was induced by ABA treatment. In contrast, expression of OsTIP2;1 and OsTIP4;3 was not seed specific as transcripts were found in vegetative tissues as well. Their respective transcript levels decreased at an early stage of seed development, whereas they increased at a later stage of seed germination and elongation of embryonic roots and shoots. When seed germination was inhibited by various stress conditions and ABA, expression of OsTIP2;1 and OsTIP4;3 was completely suppressed. In contrast, the expression level of OsTIP2;2 rapidly increased after seed imbibition and the transcript level was maintained under conditions inhibiting seed germination. These results implicate that tissue specific and developmental transcriptional regulation of OsTIPs in rice seeds depends on their specific function. In addition, OsTIPs can be discriminated by different potential phosphorylation and methylation sites in their protein structures. OsTIP3;1 and OsTIP3;2 possess unique phosphorylation signatures at their N-terminal domain, loop B and loop E, respectively. OsTIP2;1 and OsTIP4;3 have a potential methylation site at their Nterminal domain. This suggests that activity of specific tonoplast aquaporins may be regulated by post-translational modification as well as by transcriptional control.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.34 no.1
• /
• pp.74-84
• /
• 1998

A doubly resonant ultrasonic transducer has been designed as an attempt to increase the bandwidth of underwater transducers. The dual resonance conditions were accomplished by attaching a single acoustic matching layer on the front face of a Tonpilz transducer consisted of an aluminum head, a piezoelectric ring, a brass tail and a prestress bolt. A modified Mason's model was used for the performance analysis and the design of transducers, and the constructed transducers were tested experimentally and numerically by changing the impedances and thicknesses of the head, tail and matching layers in the water tank. Two distinct resonance peaks in the transmitting voltage response(TVR) of a developed transducer were observed at 34.3 and 40.4 kHz, respectively, with the difference frequency of 6.1kHz and the center frequency of 37.2kHz. The values of TVR at these frequencies were 136.5 dB re $1\;\muPa/V$ at 34.3 kHz and 136.8 dB re $1\;\muPa/V$ at 40.4 kHz, respectively. Reasonable agreement between the experimental results and the numerical results was achieved. From this result, it is expected that the generation of the distinct resonances at any two desired frequencies can be achieved through the proper choice of the matching layer to provide the impedance transformation between the transducer and the medium.

• The Korean Journal of Food And Nutrition
• /
• v.16 no.1
• /
• pp.7-14
• /
• 2003

This study mainly focused on to investigate the effects of Schizandra chinensis on the growth of a bacterium, CS6 which was isolated from kimchi. CS6 was final]y identified to lactobacillus plantarum that caused acidification of kimchi. The ethanolic extract of Schizandra chinensis(EES) inhibited the growth of L. plantarum. Minimum inhibition concentration of crude EES on L. plantarum was 62.5mg/$m\ell$. In broth culture, 5$\mu\textrm{g}$/$m\ell$ of EES completely inhibited the growth of L. plantarum during fermentation. The addition of 0.4% of EES has no apparent effect on quality including the taste and color on kimchi. It was expected that EES-containing kimchi could extend the period of preservation. Analysis of organic acids in water fractions of EES was carried out by HPLC. It is apparent that antimicrobial active fractions contained the highest concentration of succinic acid, a little tartaric acid and malic acid. Among these organic acids, succinic acid showed the strong inhibitory effect against L. plantarum CS6 in vitro. Succinic acid-containing kimchi with a concentration of 0.4 and 0.5% had the inhibitory effect on growth of L. plantarum. Inhibitory effect of EES on amylase, cellulase and pectinase was also tested. In conclusion, the present experiment demonstrated that EES inhibited the growth of L. plantarum, and various enzyme activity. EES-containing kimchi was sustained the hardness, and initial acidity during fermentation. EES was considered as the possible additive of kimchi process and EES added in kimchi increase the quality, and storage period of kimchi.