• 대한소아치과학회지
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• 제38권3호
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• pp.229-236
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• 2011

현재 시판되고 있는 ProRoot white MTA(Dentsply Tulsa, U.S.A)는 portland cement와 비슷한 성분으로 수분의 첨가로 인하여 경화 팽창하는 성질이 있고, 긴 경화 시간을 갖는다. 본 연구는 최근 개발된 OrthoMTA(BioMTA, Korea), 기존의 ProRoot white MTA(Dentsply Tulsa, U.S.A) 그리고 White portland cement(Union, Korea)를 대상으로 2008년에 개정된 치근관 충전재(KS P ISO 6876)의 요구 사항 중에서 경화 팽창과 경화 시간에 대한 연구를 하였다. 연구 결과, OrthoMTA의 경화 팽창률은 $0.08{\pm}0.02%$이었고, ProRoot white MTA, White portland cement는 각각 $0.28{\pm}0.06$, $0.80{\pm}0.25%$였다(p<0.05). 경화 시간은 각각 $307.78{\pm}3.83$분, $150.44{\pm}2.35$분, $235.33{\pm}9.07$분으로, ProRoot white MTA가 가장 짧았고, OrthoMTA가 가장 길었다(p<0.05).

• 생물환경조절학회지
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• 제7권1호
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• pp.71-77
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• 1998

본 실험은 배지의 종류 및 환경조건에 대하여 배지의 온도변화 특성을 분석하는 것을 목적으로 하였다. NFT DFT, 슬라브형 성형암면, 면상암면, 펄라이트 배지를 사용하는 순환식 양액재배시스템을 구축하였다. NFT와DFT시스템은 양액 및 재배조 내의 공기온도를 측정하였고, 고형배지는 배지온도를 측정 .비교하였다. NFT시스탬의 양액 공급유량을 3$\ell$/min, 5$\ell$/min로 할 때, 양액 온도는 주간에는 전자가 후자에 비하여 약 3t 정도 높게 나타났다. 재배조내의 공기온도도 동일한 경향을 보이며 약 2$^{\circ}C$ 정도 차이를 나타냈다. DFT 시스템의 수위를 0.8cm, 1.8cm로 할 때, 양액 온도는 주간에는 전자가 후자에 비하여 약 1-2$^{\circ}C$ 정도 높게 나타났다. 또한 재배조내의 공기 온도도 동일한 경향을 보였다. 펄라이트 배지는, 주간에 멀칭한 배지가 약 3$^{\circ}C$ 정도, 면상암면 배지도 약 3$^{\circ}C$ 정도 높게 나타났고, 슬라브형 암면배지는 주야간 멀칭한 배지가 1-4$^{\circ}C$정도 높게 나타났고. 특히 주간에 높은 온도상승을 나타냈다. 고형배지중에서 펄라이트 배지온도가 암면에 비교하여 상대적으로 야간은 낮고 주간이 높게 나타났다. 슬라브형 암면의 경우는 표면적 전체가 공기중에 노출되어 있기 때문에 다른 고형배지보다 주간의 온도상승이 크게 나타났다. 고형배지의 뿌리부분의 온도가 작물과 작물사이의 배지온도에 비하여 주간 약 3f정도 낮게 나타났으며, 야간의 경우는 거의 차이가 없었다.

• 한국농공학회논문집
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• 제47권7호
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• pp.25-33
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• 2005

This study was performed to develop environment-friendly porous polymer concrete utilizing recycled aggregates [RPPC] for permeable pavement of uniform quality with high permeability and flexural strength as well as excellent freezing and thawing resistance. The void ratios of RPPC are in the range of 15$\sim$$24\%$, showing the tendency that it is reduced to a great extent as the mixing ratio of the binder increases. The compressive and flexural strength of RPPC are in the range of 19$\sim$26 MPa and 6.2$\sim$7.4 MPa, respectively. Also, it shows a tendency to increase as the mixing ratio of the binder and filler increases. The permeability coefficients of RPPC are in the range of $6.3\times$$10_{-1}$$\sim$$1.5\times$$10_{-2}$cm/s. The flexural loads of RPPC are in the range of 18$\sim$32 KN. The weight reduction ratios obtained from the test for freezing and thawing resistance are in the range of 1.1$\sim$$2.4\%$ after 300 cycles of repeated freezing and thawing of the specimen for all mixes. The relative compressive strengths of RPPC after 300 cycles of freezing and thawing against the compressive strength before freezing and thawing test are in the range of 89$\sim$$96\%$.

• 한국농공학회논문집
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• 제49권3호
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• pp.51-60
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• 2007

This study was performed to evaluate void ratio, compressive and flexural strengths, and pH properties according to the content ratio of rice husk ash, aggregate size, and neutral treatment time of porous concrete with content of rice husk ash produced as an agricultural by-product. The SEM results for cement mortar with a 5% rice husk ash for the weight of cement formed more C-S-H hydrates due to the $SiO_2$ of rice husk ash. In the XRD test, cement mortar with a 5% rice husk ash for the weight of cement registered a higher peak point of approximately $2{\theta}=20{\sim}25^{\circ}$ compared to cement mortar without rice husk ash. According to the results of the XRD and SEM tests, the $SiO_2$ that was a major chemical element of rice husk ash generated a large amount of calcium hydroxide in the early stage of the hydration process of cement leading to the formation of ettringite. The void ratio of porous concrete with rice husk ash decreased with increasing content ratio of rice husk ash. In addition, the void ratio of porous concrete with rice husk ash decreased compared to porous concrete without rice husk ash. The compressive and flexural strength of porous concrete with a 5% and 10% content ratio of rice husk ash slightly increased compared to concrete without rice husk ash. The pH value of porous concrete rapidly decreased immediately after neutral treatment. Then, it gradually increased and decreased again after 14 days. However, the pH value was nearly the same regardless of neutral treatment time in 28 curing days. Also, for neutral treatment, the pH value of porous concrete showed appropriate pH levels (less than 9.5) in all mixtures for planting at 28 curing days.

• 한국토양비료학회지
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• 제43권4호
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• pp.478-483
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• 2010

전라북도 장수군 오미자 과원을 대상으로 토양의 이 화학적 특성을 조사하여 오미자의 품질향상, 수량증대 및 유해물질 종합관리 시스템 구축을 위한 기초조사를 수행하였다. 오미자 재배과원 토양은 대부분 양질사토였으며, 토양입단화도는 약 33.12%로 입단의 발달이 부족한 상태였으며, 토양공극율은 약 60% 수준으로 적당한 것으로 나타났다. 토양 pH는 평균 5.51이었으며, 양이온교환용량은 평균 4.11 $cmol_c\;kg^{-1}$으로 매우 낮게 나타났다. 식물영양성분은 적정 수준으로 유지되고 있었으나, 장수군 오미자 재배지 토양의 이화학적 특성 개량을 위해서는 유기물 및 석회처리 등의 토양관리가 필요한 것으로 나타났다. 조사대상 중금속의 함량은 자연함유량 수준으로 중금속 오염으로 인한 작물 안정성은 확보된 것으로 조사되었다.

• Restorative Dentistry and Endodontics
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• 제39권3호
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• pp.149-154
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• 2014

Objectives: This study was performed to evaluate the cytotoxicity of four calcium silicate-based endodontic cements at different storage times after mixing. Materials and Methods: Capillary tubes were filled with Biodentine (Septodont), Calcium Enriched Mixture (CEM cement, BioniqueDent), Tech Biosealer Endo (Tech Biosealer) and ProRoot MTA (Dentsply Tulsa Dental). Empty tubes and tubes containing Dycal were used as negative and positive control groups respectively. Filled capillary tubes were kept in 0.2 mL microtubes and incubated at $37^{\circ}C$. Each material was divided into 3 groups for testing at intervals of 24 hr, 7 day and 28 day after mixing. Human monocytes were isolated from peripheral blood mononuclear cells and cocultered with 24 hr, 7 day and 28 day samples of different materials for 24 and 48 hr. Cell viability was evaluated using an MTT assay. Results: In all groups, the viability of monocytes significantly improved with increasing storage time regardless of the incubation time (p < 0.001). After 24 hr of incubation, there was no significant difference between the materials regarding monocyte viability. However, at 48 hr of incubation, ProRoot MTA and Biodentine were less cytotoxic than CEM cement and Biosealer (p < 0.01). Conclusions: Biodentine and ProRoot MTA had similar biocompatibility. Mixing ProRoot MTA with PBS in place of distilled water had no effect on its biocompatibility. Biosealer and CEM cement after 48 hr of incubation were significantly more cytotoxic to on monocyte cells compared to ProRoot MTA and Biodentine.

• 한국지하수토양환경학회지:지하수토양환경
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• 제22권6호
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• pp.29-36
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• 2017

Universal soil loss equation (USLE) has been frequently employed to estimate potential soil loss in land since it was developed based on the statewide data measured and collected in the United States. The equation is an empirical model mainly used for U.S. soil, thus it has been recently modified to reflect Korean soil conditions and named as Korean Soil Loss Equation (KORSLE). The modified equation was implemented in ArcGIS software, and used for estimation of potential soil loss from 2003 to 2016 in the thirty-eight Water Protection Districts. Five out of the thirty-eight districts were identified as the area of potential soil erosion most severly. In those five districts, potential soil erosion were estimated to be more than 50 Mg/ha/year that requires site investigation under supervision of the Korean Ministry of Environment. Distinctive site characteristics were found in the potential soil loss estimation such that the districts of low potential soil loss had low five factors in the aggregate. However, if one of more factors are dominantly large, the potential soil loss significantly increased. This study provides a useful tool to identify the potential areas for soil erosion and the important factors that play an important role in the estimation process.

• Restorative Dentistry and Endodontics
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• 제43권4호
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• pp.36.1-36.12
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• 2018

Objectives: Direct pulp capping is a treatment for mechanically exposed pulp in which a biocompatible capping material is used to preserve pulpal vitality. Biocompatibility tests in animal studies have used a variety of experimental protocols, particularly with regard to the exposure site. In this study, pulp exposure on the occlusal and mesial surfaces of molar teeth was investigated in a rat model. Materials and Methods: A total of 58 maxillary first molars of Wistar rats were used. Forty molars were mechanically exposed and randomly assigned according to 3 factors: 1) the exposure site (occlusal or mesial), 2) the pulp-capping material (ProRoot White MTA or Bio-MA), and 3) 2 follow-up periods (1 day or 7 days) (n = 5 each). The pulp of 6 intact molars served as negative controls. The pulp of 12 molars was exposed without a capping material (n = 3 per exposure site for each period) and served as positive controls. Inflammatory cell infiltration and reparative dentin formation were histologically evaluated at 1 and 7 days using grading scores. Results: At 1 day, localized mild inflammation was detected in most teeth in all experimental groups. At 7 days, continuous/discontinuous calcified bridges were formed at exposure sites with no or few inflammatory cells. No significant differences in pulpal response according to the exposure site or calcium-silicate cement were observed. Conclusions: The location of the exposure site had no effect on rat pulpal healing. However, mesial exposures could be performed easily, with more consistent results. The pulpal responses were not significantly different between the 2 capping materials.

• Restorative Dentistry and Endodontics
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• 제48권2호
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• pp.21.1-21.15
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• 2023

Objectives: This study evaluated the effects of Biodentine (BD), Bio-C Repair (BCR), and mineral trioxide aggregate (MTA) plug on the fracture resistance of simulated immature teeth with replacement root resorption (RRR) and in vitro-induced osteoclastogenesis. Materials and Methods: Sixty bovine incisors simulating immature teeth and RRR were divided into 5 groups: BD and BCR groups, with samples completely filled with the respective materials; MTA group, which utilized a 3-mm apical MTA plug; RRR group, which received no root canal filling; and normal periodontal ligament (PL) group, which had no RRR and no root canal filling. All the teeth underwent cycling loading, and compression strength testing was performed using a universal testing machine. RAW 264.7 macrophages were treated with 1:16 extracts of BD, BCR, and MTA containing receptor activator of nuclear factor-kappa B ligand (RANKL) for 5 days. RANKL-induced osteoclast differentiation was assessed by staining with tartrate-resistant acid phosphatase. The fracture load and osteoclast number were analyzed using 1-way ANOVA and Tukey's test (α = 0.05). Results: No significant difference in fracture resistance was observed among the groups (p > 0.05). All materials similarly inhibited osteoclastogenesis (p > 0.05), except for BCR, which led to a lower percentage of osteoclasts than did MTA (p < 0.0001). Conclusions: The treatment options for non-vital immature teeth with RRR did not strengthen the teeth and promoted a similar resistance to fractures in all cases. BD, MTA, and BCR showed inhibitory effects on osteoclast differentiation, with BCR yielding improved results compared to the other materials.

• Restorative Dentistry and Endodontics
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• 제41권1호
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• pp.12-21
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• 2016

Objectives: To evaluate the effects of three acids on the microhardness of set mineral trioxide aggregate (MTA) and root dentin, and cytotoxicity on murine macrophage. Materials and Methods: OrthoMTA (BioMTA) was mixed and packed into the human root dentin blocks of 1.5 mm diameter and 5 mm height. Four groups, each of ten roots, were exposed to 10% citric acid (CA), 5% glycolic acid (GA), 17% ethylenediaminetetraacetic acid (EDTA), and saline for five minutes after setting of the OrthoMTA. Vickers surface microhardness of set MTA and dentin was measured before and after exposure to solutions, and compared between groups using one-way ANOVA with Tukey test. The microhardness value of each group was analyzed using student t test. Acid-treated OrthoMTA and dentin was examined by scanning electron microscope (SEM). Cell viability of tested solutions was assessed using WST-8 assay and murine macrophage. Results: Three test solutions reduced microhardness of dentin. 17% EDTA demonstrated severe dentinal erosion, significantly reduced the dentinal microhardness compared to 10% CA (p = 0.034) or 5% GA (p = 0.006). 10% CA or 5% GA significantly reduced the surface microhardness of set MTA compared to 17% EDTA and saline (p < 0.001). Acid-treated OrthoMTA demonstrated microporous structure with destruction of globular crystal. EDTA exhibited significantly more cellular toxicity than the other acidic solutions at diluted concentrations (0.2, 0.5, 1.0%). Conclusions: Tested acidic solutions reduced microhardness of root dentin. Five minute's application of 10% CA and 5% GA significantly reduced the microhardness of set OrthoMTA with lower cellular cytotoxicity compared to 17% EDTA.