• The Journal of Advanced Prosthodontics
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• v.14 no.3
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• pp.143-149
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• 2022

PURPOSE. Masticatory loading triggers active bone remodeling, altering alveolar bone mineral density (BMD). While dental implants are placed to bear masticatory loading, their influence on changing bone properties has not been fully investigated. Objective of this pilot study was to examine whether the dental implantation has an effect on BMD distribution of bone by comparing dentate, edentulous, and edentulous patients with implants. MATERIALS AND METHODS. Cone beam computed tomography (CBCT) images of 19 partially edentulous patients (Dent), 19 edentulous patients (Edent), and 16 edentulous patients who received implants in the mandible (Edent+Im), were obtained. CBCT images were also obtained from 5 patients within Edent+Im group, before implant placement and after implant loading. Basal cortical bone region of the mandible was digitally isolated. A histogram of gray levels proportional to BMD was obtained to assess mean, histogram standard deviation (HSD), fifth percentile of low and high values (Low₅ and High₅) of the BMD distribution. Multivariate analysis of variance and paired t-test were used to compare the BMD parameters among the 3 dental status groups and between pre- and post-implantation, respectively. RESULTS. Edentulous patients with implants had significantly greater HSD and High₅ values compared to edentulous patients (P < .013). All other comparisons were not significant (P > .097). Mean, HSD, and High₅ values significantly increased after receiving implants (P < .022). CONCLUSION. The current findings suggested that receiving dental implants promoted oral bone mineralization for edentulous patients. The longitudinal investigation could provide valuable information on understanding the effects of implantation on the behavior of oral bone quality.

• Korean Journal of Animal Reproduction
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• v.20 no.1
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• pp.35-42
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• 1996

This study was carried out to investigate the effect of straw loading method and thawing protocol on the in vitro development of in vitro produced mouse blastocysts cryopreserved by vitrification. Three loading types of straw I, Il and III on loading and sealing method were made for vitrification. The ability of the solution on straw loading methods to remain vitreous during warming was tested by exposed in air for 1 to 10 s sec. and then plunged the vitrified straws into water bath at 25°C. Embryos to be vitrified were equilibrated to the 20% EG for 5min. and exposed in EFS 40 for 1min. The plug ends of Straw I and Straw II were sealed with straw powder and Straw III was treated straw powder, followed by heat sealing and then plunged into LN$_2$. The results obtained in these experiments were summarized as follows; 1) Straw I embryo column mostly changed from transparent to opaque upon thawing without exposure in air for 3-6 sec. Straw II embryo column was I improved partially but was not remained completely vitreous during warming. However, when Straw lll loading method was used, the embryo column was remained vitreous completely. 2) High survival rates and development rates of each groups (middle blastocysts and hatching blastocysts) of vitrified embryos were obtained by using Straw III loading method than Straw I method (P<0.05). And the range of s standard error was low in Straw lll method. 3) When the embryos vitrified-frozen were placed in air for 3, 5 and l0sec. and then warmed rapidly in water bath at 25$^{\circ}C$, the survival rates after 24h of culture were 72.7-87.1% and the development rates to hatching stage after 48h of culture were 34.0-48.4%. There were no significantly differences according to exposure time in air during warming. In conclusion, the present results showed that highly survival and low standard error of vitrified-frozen mouse bIastocysts were obtained by using straw lll loading, double sealing and appropriate 2 step warming method.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.3
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• pp.267-275
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• 2011

This prospective study was designed to compare clinical outcomes of immediately loaded implant with delayed loaded implant in partially posterior edentulous patients. For test group, 42 GS III (Osstem, Korea) implants in 17 patients were loaded within 48 hours after the placement. Control group was 27 implants in 15 patients loaded at $2.6{\pm}1.7months$ from the placement surgery. Before loading, primary stability was evaluated by ISQ value. Clinical symptoms, mobility, soft tissue state was evaluated at baseline, 3 months, 6 months and 12 months of loading. Marginal bone level change was also measured with periapical radiographs. Mann-Whitney test (${\alpha}$=0.05) and repeated measured ANOVA (${\alpha}$=0.05) was used for marginal bone level change between two groups. At the baseline, mean ISQ value of test group and control group was $80.3{\pm}7.1$ and $69{\pm}17$ respectively. Test group showed 95.23% of success rate and 100% of control group was successful. At 3 and 6months of loading, significantly more bone resorption was observed in test group than in control group (p<0.05). However, there was no significant difference in the bone level change at 12months of loading between two groups (p>0.05). Marginal bone level change showed no significant difference with gender and location (p>0.05). Within the limitation of this study, when primary stability was obtained, immediate loading of GS III implant at posterior region could be predictable treatment option.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.4
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• pp.243-248
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• 2012

Purpose: The purpose of this study is to compare the removal torque between prefabricated and customized implant abutment screw. Materials and methods: Three types of implant system (Osstem, Astra, Zimmer) were used. For each system, prefabricated abutment screw (control group) and customized abutment screw (test group) were used to connect the fixture and the abutment (n = 6). Digital torque gauze was used to control the tightening torque and the screws were tightened under each manufacturer's recommendation. 10 minutes after the connection the same tightening torque was applied, and 5 minutes after the second connection, the removal torque was measured. This procedure was repeated 10 times. In the cyclic loading test, 10 minutes after the first connection to the 6 groups (n = 3), the same tightening torque was applied, and a total of 1,000,000 time loading was applied at 30 degree angle to long axis with 50 N load. Repeated measures of ANOVA test (${\alpha}$=.05) was used as statistics to evaluate the effect of repeated loading number on the removal torque. Independent t-test was used to evaluate the difference in removal torque after cyclic loading. Results: The removal torque significantly decreased as the number of loading repetition increased (P<.05). In the 10 time repetition test, there was no significant difference between the prefabricated and customized implant abutment screw of the 3 implant system (P<.05). Also in the cyclic loading test, there was no significant difference between the prefabricated and customized implant abutment screw of the 3 implant system (P<.05). Conclusion: Within the limitation of this study, there was no significant difference in the removal torque between the prefabricated abutment screw and customized abutment screws.

• Korean Journal of Ecology and Environment
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• v.34 no.1 s.93
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• pp.62-69
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• 2001

This study was investigated discharge and water quality for rainy days at the inflow streams (Gog-Kyo, Mu-Han, Sap-Kyo and Nam-Won) into Lake Sap-Kyo from June to November of 1999. The eventual aim of this study was to improve the water quality of Lake Sap-Kyo. Therefore, in order to reduce inflow pollutants loading into Lake Sap-Kyo, we investigated characteristics of stormwater runoff and estimated pollutant loading for the rainy season. The results of that Sap-Kyo stream is $5.75\;m^3/sec$ flow and influences water quantity of Lake Sap-Kyo greatly during the dry weather. Gog-Kyo stream influence to quantity of Lake Sap-Kyo greatly for the rainy days. Gog-Kyo stream and Sap-Kyo stream are $12.13\;m^3/sec$ and $8.49\;m^3/sec$, respectively. The reason is that the watershed area of Gog-Kyo stream is larger than other streams. When we prepare to plan management to improve the water quality of Lake Sap-Kyo, we have to consider that runoff characteristics by land use. Among the annual total pollutants loading inflow Lake Sap-Kyo, the ratio of non-point pollutants loading estimated that SS, BOD, T-N and T-P are 62%, 43%, 41% and 27%, respectively. Therefore, in order to improve water quality of Lake Sap-Kyo, we have to reduce non-point pollutants loading.

• Ecology and Resilient Infrastructure
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• v.4 no.4
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• pp.226-236
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• 2017

In this study, we aimed to analyze the characteristics of water quality variation at Kyeongan Stream for a decade and to investigate by the flow-loading equation. The correlation analysis of water quality parameters and the influence factors were examined by statistical analysis. The characteristics of water quality variation showed that the fluctuations in $BOD_5$, $COD_{Mn}$ and TOC were repeated from year to year. TN and TP were decreased by year. By the flow-loading equation, the concentrations of $BOD_5$, $COD_{Mn}$, TOC and TN were decreased when the flow rate was on the rise. However, the flow did not affect the concentration of TP. According to correlation analysis, $BOD_5$ was highly correlated with $COD_{Mn}$ and TOC with the correlation coefficients of 0.890 (p<0.01) and 0.721 (p<0.01). The result of factor analysis, we identified that the water quality in Kyeongan Stream has been highly influenced by the organic matter index, followed by nitrogenous substance depending on the seasonal variations and the influx of suspended solid in accordance with the increase of flow.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.4
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• pp.35-44
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• 1999

In this study, it was attempted to remove nitrate and carbon in a single-stage reactor using acetate as substrate. Hybrid type upflow sludge baffled filter reactor was adopted using anaerobic sludge. Sludge bed in the bottom of reactor was intended to remove carbon and nitrate by denitrification and methanogenesis. And floating media in the upper part of reactor were intended to remove remaining carbon which was not removed due to the inhibition of nitrogen oxide on methane producing bacteria. The reactor removed over 96% of COD and most of nitrate with volumetric loading rate of $4.0kgCOD/m^3{\cdot}day$, hydraulic retention time of 24hr, 4,000mgCOD/L, and $266mgNO_3-N/L$. Nitrate in anaerobic sludge was converted to nitrogen gas(denitrification) or ammonia (ammonification) according to pH of influent, COD removal efficiency was easily affected by the change of volumetric loading rates and nitrate concentration. And when influent pH was about 4.7, most nitrate changed to ammonia while when influent pH was about 6.8~7.0, most nitrate denitrified independent of $COD/NO_3-N$ ratio. Most granules were gray and a few were black. In gray-colored granule, black inner side was covered with gray substance and SEM illustrated Methanoccoci type microorganisms which were compact spherical shape. Anaerobic filter removed residual COD effectively which was left in sludge bed due to the inhibition of nitrogen oxide.

• Journal of Environmental Health Sciences
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• v.35 no.5
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• pp.365-375
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• 2009

Agriculture reservoirs need a systematic approach that can control water purity and water improvement. The area under study, Bunam Lake exceeds the agricultural water standard level due to contamination from the upper stream. When the Taean Enterprise City was planned, the water quality improvement plan was applied to minimize the environmental change. However, in order to continuously maintain the water quality in the Bunam Lake, it was essential to apply the Total Pollution Load Management System (TPLMs). In order to achieve the targeted water quality in the Bunam Lake, standard flow rates and targeted water quality levels were applied to obtain the loading capacity which is as follows : BOD 1,891.2 kg/d, T-N 1,945.7 kg/d, T-P 131.7 kg/d. Also, the regional development load was calculated as, BOD 1,083.6 kg/d, T-N 942.2 kg/d, T-P 61.8 kg/d, which is required to be deceased :- by BOD 378.4 kg/d, T-N 198.9 kg/d, T-P 31.6 kg/d in order to safely achieve the targeted water quality in the Bunam Lake.

• Magazine of the Korean Society of Agricultural Engineers
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• v.31 no.3
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• pp.93-102
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• 1989

With an objective to provide basic information for the management and the prediction of eutrophication in lentic water Systems, total amount of Kjeldahl nitrogen(T-N) and phosphorous(T-P) from irrigated water and drained water from flooded paddies were investigated during the rice growing period of 1988. A 29.3 ha paddies near Jungnam-myun, HwaSung-gun, Gyungi Province, Korea was instrumented for measuring runoff and sampling irrigated water and drained water from paddies. The following conclusions may be drawn from the result of this study. 1.During 115 days of investigation, T-N load for paddies was 362.6kg and T-P 63.44kg.These would be converted to 12.4kg T-N/ha and 2.17kg T-P/ha, respectively. 2.The T-N and T-P loadings in different periods showed a significant difference. The 25% of T-N loading was drained soon after fertilization period and 60% was drained during the rainy season from July 5 to July 24. 3.Annual loadings from paddies could be calculated to 30kg T-N/ha/year and 52kg T-P/ha/year considering non-measurement periods. 4.After the rainy season, the nutrient loads from drained water showed much less than those from irrigated water, and it may be suggested that the paddies would act as a stabilization pond. 5.The average concentrations of nutrients at 0.9km downstream from investigated paddies were 2.02(T-N) mg/l and 0.52(T-P) mg/I, which were 1.82(T-N) mg/l and 0.056(T-P)mg/l lower than those of drained water from paddies.

• Applied Chemistry for Engineering
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• v.19 no.4
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• pp.432-438
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• 2008

Hydrogenation reactions of p-toluidine over Ru/C were performed while varying reaction temperature, the hydrogen pressure, catalyst loading, solvent, and alkali additive and the effects on the reaction rates and product distribution were examined. 4-Methylcyclohexylamine was generated as a main product and bis(4-methyl cyclohexyl)amine was obtained as a resentative side-product for the hydrogenation reaction of p-toluidine. The selectivity of MCHA decreased with reaction temperature and the hydrogen pressure while increased with catalyst loading. IPA was the best solvent for MCHA. A mechanism of hydrogenation reaction of p-toluidine was suggested from the results. It was found that the presence of alkali salt increased MCHA by reducing BMCHA and rates of hydrogen reaction increased.