• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.1
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• pp.10-19
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• 2015

Purpose: The aim of the present study was to evaluate the long-term survival of implants retrospectively and determine the risk factors associated with implant failure. Materials and Methods: Of all implants that were placed at the Department of Periodontology of the Dental Hospital of Gangneung-Wonju National University from January 1998 to December 2012, 2265 implants that were followed up until June 2013 were included in this study. Data were collected from clinical and radiographic examinations from previous visits. The information gathered included gender, age, smoking status, implant diameter, implant length, surface of implant, location of implant within the dental arch, surgical techniques and existence of complications. Results: The survival rate before loading was 98.9%. The cumulative survival rate after 5 years of loading was 97.2%, and after 15 years of loading was 95.2%. In a simple logistic regression analysis, gender (P = 0.016), smoking status (P = 0.001), location of implant (P = 0.020) and existence of complications (P = 0.002) were statistically associated with implant failure and included in the multiple regression analysis. As a result of multiple logistic regression analysis, the variables statistically associated with implant failure (P < 0.05) were smoking status (P = 0.049) and existence of complications (P < 0.001). Conclusion: The cumulative survival rate of dental implants after 15 years of loading was 95.2% and that the variables statistically associated with implant failure were smoking status and existence of complications.

• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.827-833
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• 1995

Temperature distribution tests for a water cascading horizontal retort utilizing superheated water with overpressure as a heating medium were carried out under three different loading conditions, that is, empty(P-0), half-fully(P-3000) and fully(P-6000) loaded operating conditions. Tank volume and full loading capacity of sterilizer used for this study were about 5,900 liter and 1,140 kg(6000 pouches having 190 g weight each), respectively. Set point condition for sterilization was $122^{\circ}C$, 23 minutes and pressure was maintained in the range of $1.8{\sim}2.0\;kg/cm^2$ during sterilization. For each experiment, time-temperature data and F values were obtained from temperature microprocessor($F_0$ monitor). There were significant variations in the temperature distribution at different positions in the sterilizer. The temperature distribution was also affected by the pouch loading condition significantly. The application of the temperature distribution test to a product (retort pouched curry sauce) was conducted at the fully(P-6000) loading condition. Although heat transfer parameters($f_h\;and\;f_c$), and F values were varied with the position of sterilizer, sensory evaluation showed that the temperature distribution of the sterilizer used in this study didn't affect the quality of retorted curry sauce.

• Korean Journal of Animal Reproduction
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• v.15 no.1
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• pp.49-57
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• 1991

This study was carried out to investigate the effect of equilibration time, precooling and straw loading method on the post-thaw survival rates of mouse embryos cryopreserved by vitrification method. The effect of the vitrification procedure on the damage of the embryos was also examined by the straining of nuclei using Hoechst 33342. The results obtained were summarized as follows; 1. The equilibration in Medium-1 for 10 minutes was considered to be the optimum equilibration time. Embryos equilibrated in Medium-1 for 10 minutes(81.0%) showed significantly(P<0.05) higher survival rates than those equilibrated for 5 minutes(40.0%) or 15 minutes(74.1%). 2. The survival rate of embryos cryopreserved using the double Medium-2 column(81.0%) was significantly(P<0.01) higher than that using the single Medium-2 column, whish was considered to be due to the double Medium-2 column method being more reliable for preventing contamination of diluent solution of 1M sucrose. 3. The survival rate of compacted morula stage embryos cryopreserved with the precooled and non-precooled Medium-2 was not significantly(P<0.05) different. 4. The number of blastomeres of embryos at late blastocyst stage after culture of mouse morulae for 24 to 28hours was significantly(P<0.05) decreased by freezing embryos using vitrification(53.3${\pm}$1.6 vs 41.4${\pm}$1.5), which was considered to be due to the damage of embryos during vitrification and the delay of embryo development by handling in vitro. 5. The vitrification procedure is considered to be a very simple and efficient method for cryopreservation of embryos at early developmental stage.

• Korean Journal of Applied Biomechanics
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• v.28 no.2
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• pp.101-108
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• 2018

Objective: The aim of this study was to investigate gender differences in ground reaction force (GRF) components among different speeds of running. Method: Twenty men ($age=22.4{\pm}1.6years$, $mass=73.4{\pm}8.4kg$, $height=176.2{\pm}5.6cm$) and twenty women ($age=20.7{\pm}1.2years$, $mass=55.0{\pm}8.2kg$, $height=163.9{\pm}5.3cm$) participated in this study. All participants were asked to run on an instrumented dual belt treadmill (Bertec, USA) at 8, 12, and 16 km/h for 3 min, after warming up. GRF data were collected from 30 strides while they were running. Hypotheses were tested using one-way ANOVA, and level of significance was set at p-value <.05. Results: The time to passive peaks was significantly earlier in women than in men at three different running speeds (p<.05). Further, the impact loading rates were significantly greater in women than in men at three different running speeds (p<.05). Moreover, the propulsive peak at 8 km/h, which is the slowest running speed, was significantly greater in women than in men (p<.05), and the vertical impulse at 16 km/h, which is the fastest running speed, was significantly greater in men than in women (p<.05). The absolute anteroposterior impulse at 8 km/h was significantly greater in women than in men (p<.05). In addition, as the running speed increased, impact peak, active peak, impact loading rate, breaking peak, propulsive peak, and anteroposterior impulse were significantly increased, but vertical impulse was significantly decreased (p<.05). Conclusion: The impact loading rate is greater in women than in men regardless of different running speeds. Therefore, female runners might be exposed to the risk of potential injuries related to the bone and ligament. Moreover, increased running speeds could lead to higher possibility of running injuries.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.12
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• pp.1126-1133
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• 2010

A two-stage biofilter was constructed and utilized to determine the removal efficiency when treating dynamic loading of a mixture of odorous compounds including benzene, toluene, p-xylene, ammonia and hydrogen sulfide. A yeast strain, Candida tropicalis, and a sulfur oxidizing bacterial (SOB) strain, Acidithiobacillus caldus sp., were immobilized in polyurethane media and packed in the two-stage biofilter. The experiment of dynamic loading variation was composed of (1) stepwise loading variation of all the odorous compounds (total EC test), (2) stepwise loading variation of each odorous compound, and (3) intermittent loading variation with 2-day-off and 3-day-on. The total EC test showed that the maximum elimination capacity was $61\;g/m^3/hr$ for total VOCs, and 5.2 and $9.1\;g/m^3/hr$ for ammonia and hydrogen, respectively. In addition, the inhibition between VOCs was observed when the loading of each individual VOC was varied. Especially the stepwise increase in toluene loading resulted in decreases of benzene and p-xylene removal efficiencies about 30% and 25%, respectively. However, the inhibition between organic and inorganic compounds was not observed. The intermittent loading variation with 2-day-off and 3-day-on showed that greater than 95% of the overall removal efficiency was restored in two days after the loading resumed. Consequently, the two-stage biofilter packed with immobilized microorganisms showed advantages over conventional biofilters for the simultaneous treatment of the mixture of organic and inorganic odorous compounds.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.233-240
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• 2001

This research was conducted with the aim of efficiently managing large scale of rivers such like Songyang-river through predicting water quality change with analyzing the characteristics of the flowing in nutrients and pollutants. The main result will be used as basic data for effectively operating reservoirs through controling water quality and quantity. The relationship between quantity of flow and water quality was analyzed and pollution loading into the basin was estimated. Three areas of Soyang-river upstream and one area of Suip-cheon in Yanggu-gun were selected as research sites. Flow and water quality were measured simultaneously. The relation between quantity of discharge and pollution concentration and between quantity of discharge and pollution loading were analyzed by statistical method, respectively. We provided a rating curve through measuring quantity of discharge(collecting quantity of discharge) and pollutograph and pollution loading curve through water quality data. Also, we analyzed the correlation between quantity of discharge per unit area and pollution loading per unit area in each basin. As resurt of this research, Buk-cheon spot revealed an excellent first grade water quality for the items including $BOD_5$, DO, and SS. The correlation coefficient between Buk-cheon spot's quantity of discharge and pollution loading was 0.896~0.996, showing the validity of analysis applying correlation curve formula of quantity of discharge and pollution loading in the same spot. Also, pollution loading per unit area of the items including $BOD_5$, COD, DO, SS, T-N, T-P increased as the area of basins get increased following the sequence of Buk-cheon, Suip-cheon, Naelin-cheon spots.

• The Journal of Advanced Prosthodontics
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• v.13 no.3
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• pp.152-159
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• 2021

Purpose. The aim of this study was to investigate to what extent cyclic load affects the screwless implant-abutment connection for Morse taper dental implants. Materials and Methods. 16 implants (SICvantage max) and 16 abutments (Swiss Cross) were used. The screwless implant-abutment connection was subjected to 10,000 cycles of axial loading with a maximum force of 120 N. For the pull-off testing, before and after the same cyclic loading, the required force for disconnecting the remaining 6 implant-abutment connections was measured. The surface of 10 abutments was examined using a scanning electron microscope 120× before and after loading. Results. The pull-off test showed a significant decrease in the vertical force required to pull the abutment from the implant with mean 229.39 N ± 18.23 before loading, and 204.30 N ± 13.51 after loading (P<.01). Apart from the appearance of polished surface areas and slight signs of wear, no visible damages were found on the abutments. Conclusion. The deformation on the polished abutment surface might represent the result of micro movements within the implant-abutment connection during loading. Although there was a decrease of the pull-off force values after cyclic loading, this might not have a notable effect on the clinical performance.

• Wind and Structures
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• v.6 no.2
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• pp.165-177
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• 2003

• Ocean and Polar Research
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• v.25 no.3
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• pp.277-286
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• 2003

Nitrification performance of fixed film biofilters using coarse sand, loess bead, or styrofoam beads in biofilter columns 1 meter high and 30cm in diameter were studied at different hydraulic and organic matter loading rates. Synthetic wastewater was supplied to the culture tank in order to maintain desired TAN concentrations in inlet water to biofilters. All the biofilters were conditioned 5 months before start of sampling. TAN and $NO_2-N$ conversion rates increased with an increase in the hydraulic loading rate (HLR). However, the improvement in biofilter performance was not linearly correlated to HLR in styrofoam bead filters. This is mainly due to the characteristics of the styrofoam beads used. TAN conversion rates of sand filters increased with the increase of HLR up to $200m^3/m^2$. per day. No increase in the TAN conversion rate was observed at the highest HLR since flooding on the media surface took place. HLR had a significant impact on the TAN conversion rates in loess bead filter up to the highest HLR tested (P<0.05). TAN conversion rates were much less at organic matter loading rates of 9 and 18kg $O_2/m^3$ per day than those without the addition of organic matter in styrofoam bead filters. The addition of glucose resulted in a reduction of the TAN conversion rate from 540 to 284g $TAN/m^3$ per day. No significant difference of TAN conversion rates between the two organic matter loading rates was found (p<0.05). This indicates that the impact of organic matter on nitrification becomes less and less sensitive with an increase in the COD/TAN ratio. At an organic matter loading rate of 9kg $O_2/m^3$. per day, a great reduction of TAN conversion rates was observed in sand filters and loess bead filters. Clearly, organic matter can be one of the most Important Impacting factors on nitrification. $NO_2-N$ conversion rates showed a similar trend for TAN. Based on the TAN and nitrite conversion rates, styrofoam beads showed the best performance among the three filter media tested. Also, the low gravity and price of styrofoam beads make the handling easier and more cost-effective for commercial application. The results obtained at the highest organic matter loading rates can be used in the biofilter design in recirculating aquaculture system.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.2
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• pp.61-74
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• 2007

A mathematical modeling program called Hydrological Simulation Program-FORTRAN (HSPF) developed by the United States Environmental Protection Agency (EPA) was applied to Hwaseong watershed. It was run under BASINS (Better Assessment Science for Integrating Point and Nonpoint Sources) program, and the model was validated using monitoring data of $2002{\sim}2005$. The model efficiency of runoff ranged from good to fair in comparison between simulated and observed data, while it was from very good to poor in the water quality parameters. But its reliability and performance were within the expectation considering complexity of the watershed and pollutant sources. The nonpoint source (NPS) loading for T-N and T-P during the monsoon rainy season (June to September) was about 80% of total NPS loading, and runoff volume was also in a similar range. However, NPS loading for BOD ($55{\sim}60%$) didn't depend on rainfall because BOD was mostly discharged from point source (more than 70%). And water quality was not necessarily high during the rainy season, and showed a decreasing trend with increasing water flow. BASINS/HSPF was applied to the Hwaseong watershed successfully without difficulty, and it was found that the model could be used conveniently to assess watershed characteristics and to estimate pollutant loading including point and nonpoint sources in watershed scale.