• The Journal of Korean Academy of Prosthodontics
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• v.55 no.1
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• pp.26-31
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• 2017

Purpose: This study was to assess clinically the success rates and technical complications of cement-retained implant-supported single crowns and splinted crowns with zirconia frameworks. Materials and methods: 75 (single crowns: 51, splinted crowns: 24) cement-retained implant-supported single crowns and splinted crowns with zirconia frameworks which were restored in 67 patients were investigated for the evaluation of the success rates and technical complications. All restorations were cemented with temporary cement. Age, gender, restoration position, opposing teeth, restoration type were assessed as possible factors affecting technical complications. Results: During the mean observation period of 22.2 months, cumulative success rates of all restorations were 66.9 (73.2 - 60.6)%. Retention loss was found in 16 restorations (single crowns: 14, splinted crowns: 2), abutment screw loosening and veneer porcelain fracture were found in each 2 single crowns, respectively. According to a Kaplan-Meier survival analysis of single crowns and splinted crowns, the cumulative success rates were 58.9 (66.6 - 51.2)%, 87.5 (96.1 - 78.9)%, respectively. There was a statistically significant difference. The other possible factors did not have a significant effect on the technical complications. Conclusion: Retention loss was the most frequent technical complication. Abutment screw loosening and veneer porcelain fracture were found rarely in single crowns only. Age, gender, restoration position, and antagonist did not have significant effect on the technical complications. Splinted crowns had a higher success rate than single crowns.

• Journal of the Korean Vacuum Society
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• v.8 no.3B
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• pp.353-360
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• 1999

The global balance model is applied to investigate the transient behavior of the electron density and temperature in helicon plasmas. The power absorption calculated from the solutions of the Maxwell equations is used in solving the power balance equation. A balance model for the neutral gas is also considered to fins its density self-consistently. It is turned out that the numerical results reasonably explain consequences of the ion pumping effect including the occurrence of two distinct modes of pulsed helicon discharge which have been observed experimentally. The behavior of the discharge parameters are fond to be primarily dependent on the power absorption and the gas flow rate, but the pressure controls the electron density and temperature of the final steady state as well as the transient state even with the same flow rate. Finally, it is shown that the electron density virtually the linear relationship between the density and the magnetic field is retained for a higher pressure when the effect of the ion pumping is negligible.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.4
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• pp.447-452
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• 1988

This paper proposes a hybrid image coding in order to improve the coding performance by combining the BTC with the DPCM. And utilizing the human perceptual characteristics, a new objective image quality evaluation method has been proposed to obtain an excellent result in good agreement with the subjective quality evaluation. A hyb-1 method consisting of the DPCM and the AMBTC has retained a good picture quality at the bit rate of 1.5 bits/pel. A hyb-3 method combining the EBTC-3 with the DPCM has scarcely degraded the picture quality compared with the original image at the bit rate of 2.1 bits/pel. A newly proposed mehtod of picture quality evaluation accumulating a blocky noise at the edge block and an impulsive noise at the flat block selectively has been coincident with the subjective evaluation of quality.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3227-3235
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• 1994

This paper deals with an evaluation of the residual stress due to shot peening induced in a carburized gear tooth and its application to the fatigue crack propagation problem. A practical method is proposed on the basis of the assumption that the residual stress is caused by the difference of volume expansion in the case and the core, and the influence of both the reduction of retained austenite and the strain due to shot peening are considered. The evaluated residual stress is close to the measured stress, though the surface stress is rather overestimated. The stress intensity factor is computed by the influence function method, and it is shown that the factor is decreased by the residual stress in shot peened gear tooth. The shot peening is fairly effective to the reduction of fatigue crack growth rate. The crack propagation is simulated and the resistance due to shot peening is quantitatively demonstrated and discussed.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.5
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• pp.583-590
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• 2022

In this paper, the performance characteristics of the 2 vane pump for wastewater treatment were investigated using response surface method(RSM) with commercial computation fluid dynamics(CFD) software. Design variables of wastewater treatment pump were defined with the meridional plane of the 2 vane pump impeller. The objective functions were defined as the total head and the efficiency at the design flow rate. The hydraulic performance of optimum model was verified by numerical analysis and the reliability of the model was retained by comparison of numerical analysis and comparative analysis with the reference model.

• Journal of Electrochemical Science and Technology
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• v.11 no.4
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• pp.406-410
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• 2020

Despite a simple preparation of manganese oxide (MnO₂) nanowires by electrodeposition, the improvement in specific capacitance (C_sp) and voltammetric response of the MnO₂ nanowire-based electrodes has been quite limited. This is attributed to the poor electrical conductivity of MnO₂ and its dense bulk morphology due to the aggregation of the nanowires. This study investigated the capacitive performance of MnO₂ nanowires electrodeposited on agarose thin films. The good ionic conductivity and porous network of the agarose film provided favorable growth conditions for the MnO₂ nanowires with suppressed aggregation. A maximum C_sp value of 686 F/g measured at a scan rate of 10 mV/s was obtained, which was significantly larger than that of 314 F/g for the agarose-free MnO₂ electrode at the same scan rate. The rate capability was also improved. The C_sp measured at a high scan rate of 100 mV/s retained 74.0% of the value measured at 10 mV/s, superior to the retention of 71.1% for the agarose-free MnO₂ electrode.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.9
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• pp.25-37
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• 2022

Investment decisions are one of the most fundamental issues in financial management. This study aims to determine the factors that affect investment decisions in the energy industry and to contribute to the companies in this industry to develop strategic policies. The System GMM analyzes were carried out using the data of companies registered on the stock exchange for the period 2000-2015. The findings showed that industrial competition and firm size were important factors influencing the investment decisions of firms in the energy industry. The findings indicated a nonlinear relationship between industrial competition and the rate of investment in the energy sector. Depending on the firm's size, the effect of industrial competitiveness on investment varies. Smaller businesses are more impacted by the level of competition than larger ones. The investment rate decreases depending on the increase in cash holding level and firm risk. When the subgroups in the energy industry are examined, it is determined that they reveal some differences in terms of financial structure. A higher investment rate results from a higher retained earnings ratio. The investment rate of firms falls as a company's risk level and sales revenue variability increase.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.143-150
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• 2008

EGR(exhaust gas recirculation) is an attractive means of improving the fuel economy of spark ignition engines, as it offers the benefits of charge dilution (lower pumping and cooling losses) while allowing stoichiometric fuelling to be retained for applications using the three-way catalysts. However, the occurrence of excessive cyclic variation with high EGR normally prevents substantial fuel economy improvements from being achieved in practice. Therefore, the optimum EGR rate in Gasoline-Hybrid engine should be carefully determined in order to achieve low fuel consumption and low exhaust emission. In this study, 2 liters gasoline engine with E-EGR system was used to investigate the effects of EGR on fuel economy, combustion stability, engine performance and exhaust emissions. EGR tolerance with load variation was found to be more sensitive than with rpm variation. With optimal EGR rates, the fuel consumption was improved by 5.5% while a combustion stability was guaranteed.

• Journal of Environmental Science International
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• v.25 no.1
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• pp.173-179
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• 2016

Leaf water and osmotic potential, chlorophyll content, photosynthetic rate, and electrolyte leakage were measured to evaluate tolerance to water stress in wild-type (WT) and transgenic tobacco plants (TR) expressing copper/zink superoxide dismutase (CuZnSOD) and ascorbate peroxidase (APX) in chloroplasts. Leaf water potential of both WT and TR plants decreased similarly under water stress condition. However, leaf osmotic potential of TR plants more negatively decreased in the process of dehydration, compared with WT plants, suggesting osmotic adjustment. Stomatal conductance (Gs) in WT plants markedly decreased from the Day 4 after withholding water, while that in TR plants retained relatively high values. Relatively low chlorophyll content and photosynthetic rate under water stress were shown in WT plants since $4^{th}$ day after treatment. In particular, damage indicated by electrolyte leakage during water stress was higher in WT plants than in TR plants. On the other hand, SOD and APX activity was remarkably higher in TR plants. These results indicate that transgenic tobacco plants expressing copper/zink superoxide dismutase (CuZnSOD) and ascorbate peroxidase (APX) in chloroplasts improve tolerance to water stress.

• Journal of Veterinary Clinics
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• v.28 no.4
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• pp.339-343
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• 2011

This study determined the effects of twin birth on subsequent postpartum disorders, culling and reproductive performance, and its risk factors in dairy cows. Detailed data related to reproduction, health, and calving events, including dates of artificial insemination (AI) and calving, hormonal treatment prior to conception, cow parity, twin birth, retained placenta, metabolic disorders, and endometritis were collected from 1,717 individual calvings on 9 dairy farms. The incidence rate of twin birth was 3.4%. Gestation length was shorter in cows with twin birth ($270.6{\pm}2.0$ days) than cows giving birth to singletons ($279.5{\pm}0.2$ days, P < 0.01). The incidence of retained placenta (47.5 vs. 16.0%), metabolic disorders (18.6 vs. 3.8%) endometritis (62.7 vs. 28.2%), and culling rate (32.2 vs. 16.5%) was greater in cows with twin birth than in cows giving birth to singletons, respectively (P < 0.01). The hazard of pregnancy (adjusted hazard ratio, AHR) by 210 days in milk analyzed using Cox proportional hazards model was affected by calving season, in that the rate of pregnancy for cows calved during spring was less than for cows calved during winter (AHR = 0.80; P = 0.01); this was also true for endometritis (AHR = 0.46, P < 0.01). AHR was not affected by twin birth. Logistic analysis demonstrated that increasing the cow parity (P < 0.01) and hormonal treatment prior to conception (adjusted odds ratio, AOR = 1.84, P < 0.05) increased the risk of twin birth. These results demonstrate that twin births are responsible for severe economic losses through the increased occurrence of postpartum disorders and culling; thus, appropriate management for the deleterious impact of twin birth, and/or reducing the risk factors by herd control regarding cow parity and the use of reproductive hormones prior to conception might be necessary.