• The Journal of Advanced Prosthodontics
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• v.7 no.4
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• pp.288-293
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• 2015

PURPOSE. The aim of this study was to evaluate the effect of cyclic loading and screw retightening on reverse torque value (RTV) in external and internal type implants. MATERIALS AND METHODS. Cement-retained abutments were connected with 30 Ncm torque to external and internal type implants. Experimental groups were classified according to implant connection type and retightening/loading protocol. In groups with no retightening, RTV was evaluated after cyclic loading for 100,000 cycles. In groups with retightening, RTV was measured after 3, 10, 100 cycles as well as every 20,000 cycles until 100,000 cycles of loading. RESULTS. Every group showed decreased RTV after cyclic loading. Before and after cyclic loading, external type implants had significantly higher RTVs than internal type implants. In external type implants, retightening did not affect the decrease in RTV. In contrast, retightening 5 times and retightening after 10 cycles of dynamic loading was effective for maintaining RTV in internal type implants. CONCLUSION. Retightening of screws is more effective in internal type implants than external type implants. Retightening of screws is recommended in the early stage of functional loading.

• Journal of Integrative Natural Science
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• v.16 no.4
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• pp.139-145
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• 2023

Due to changes in the distribution system and increased demand for renewable energy, interest in technology to increase the limit capacity of distributed energy grid connection using grid flexible resources is also increasing. Recently, the distribution system system is changing due to the increase in distributed power from renewable energy, and as a result, problems with the limited capacity of the distribution system, such as waiting for renewable energy to connect and increased overload, are occurring. According to the power generation facility status report provided by the Korea Power Exchange, of the total power generation capacity of 134,020 MW as of 2021, power generation capacity through new and renewable energy facilities is 24,855 MW, accounting for approximately 19%, and among them, power generation through solar power accounts for a total portion of the total. It was analyzed that the proportion of solar power generation facilities was high, accounting for 75%. In the future, the proportion of new and renewable energy power generation facilities is expected to increase, and accordingly, an efficient operation plan for the distribution system is needed. Advanced country-type NWAs that can integrate the operation and management of load characteristics for each line of the distribution system, power distribution, regional characteristics, and economic feasibility of distributed power in order to improve distribution network use efficiency without expanding distribution facilities due to the expansion of renewable energy. An integrated operating system is needed. In this study, in order to improve the efficiency of distribution network use without expanding distribution facilities due to the expansion of renewable energy, we developed a method that can integrate the operation and management of load characteristics for each line of the distribution system, power distribution, regional characteristics, and economic feasibility of distributed power. We want to develop an integrated operation system for NWAs similar to that of advanced countries.

• Journal of Korean Society of Steel Construction
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• v.25 no.3
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• pp.233-242
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• 2013

This paper reports a new beam-to-column connection that is suitable for use in the weak axis of a column. The proposed system mainly uses bolts, and it minimizes the use of welding, which is generally difficult to perform onsite. In this system, a H-shape steel beam is joined to a H-shape steel column by bolted splices at the top flange and without a scallop at the web. The structural performance of the proposed connection was verified through full-scale tests of nine specimens, taking into account the effects of the geometry and arrangement of the plate.

• Journal of Advanced Navigation Technology
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• v.6 no.1
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• pp.77-83
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• 2002

The emergence of Bluetooth as a radio interface scheme has allowed electronic devices to be instantly interconnected as ad-hoc networks. These short range ad-hoc wireless networks are called piconets, operated in the unlicensed 2.45 GHz ISM(Industrial, Scientific, Medical) band where up to eight devices may be used to configure single or overlapping piconets. In this paper, we have simulated the PER(Packet Error Rate), the ratio of received packet and payload BER(Bit Error Rate) of piconet with packet types of Bluetooth ACL/SCO(Asynchronous Connection Less/Synchronous Connection Oriented) link over wireless ad-hoc environment. The Rayleigh fading effects are considered as channel model, and the simulation results are based on the baseband model of Bluetooth specification. From the simulation results, the PER and the throughput of Bluetooth piconet are sensibly affected by the packet type of ACL/SCO link.

• The Journal of Advanced Prosthodontics
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• v.11 no.6
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• pp.305-312
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• 2019

PURPOSE. The purpose of this study was to compare computer-aided design/computer-aided manufacturing (CAD/CAM) abutment and prefabricated abutment in Morse taper internal connection type implants after cyclic loading. MATERIALS AND METHODS. The study was conducted with internal type implants of two different manufacturers (Group Os, De). Fourteen assemblies were prepared for each manufacturer group and divided into 2 groups (n=7): prefabricated abutments (Os-P, De-P) and CAD/CAM abutments (Os-C, De-C). The amount of axial displacement and the removal torque values (RTVs) were measured before and after cyclic loading (10⁶ cycles, 3 Hz with 150 N), and the tensile removal force to dislodge the abutments was measured after cyclic loading. A repeated measures ANOVA and a pattern analysis based on the logarithmic regression model were conducted to evaluate the effect of cyclic loading on the axial displacement. The Wilcoxon signed-rank test and the Mann-Whitney test was conducted for comparison of RTV reduction% and tensile removal forces. RESULTS. There was no significant difference between CAD/CAM abutments and prefabricated abutments in axial displacement and tensile removal force; however, significantly greater RTV reduction% after cyclic loading was observed in CAD/CAM abutments. The correlation among the axial displacement, the RTV, and the tensile removal force was not significant. CONCLUSION. The use of CAD/CAM abutment did not significantly affect the amount of axial displacement and tensile removal force, but presented a significantly greater removal torque reduction% than prefabricated abutments. The connection stability due to the friction at the abutment-implant interface of CAD/CAM abutments may not be different from prefabricated abutment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.207-214
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• 2011

Ultra High Performance Concrete (UHPC), which is characterized by its high strength and advanced ductile behavior that is much superior to those of convention concrete, is a useful material to make thinner and longer bridges. The precast segmental construction method utilizing UHPC has been mainly studied because cast-in-place UHPC is very difficult and complicate to be achieved. As a part of those research, the structural performance evaluation of different types of joint connection method for hybrid cable-stayed bridge utilizing UHPC by using nonlinear analyses is performed in this study. The bond stress at joint is obtained by section force analyses for a 600 m cable-stayed bridge deck, and compared with the required bond stress at joint. Analysis results show that the U Type connection and straight type connection resist the highest ultimate load and bond strength, respectively. In addition, all considered joint connection systems satisfy the bond performances at joint required in the final stage of cable-stayed bridge utilizing UHPC.

• Korean Institute of Interior Design Journal
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• v.20 no.6
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• pp.27-35
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• 2011

Various thoughts about the concept of space have brought a variety of paradigms to the trend. Just as existing information innovation applied activity and function of physical space for computers to overcome time and space limits, future space transplants intelligence to all the objects as organic whole in electronic and physical space by using IT technology to create emotional space. The most universal housing space in our living has had considerable changes in application of life style and technology. However, advanced technology space which corresponds to acceptance and desires of residents does not meet the needs and emotion of residents because of its limited network system. Therefore, it should be transformed into smart space which stimulates human emotion in the trend of advanced technology culture. As future residential space needs technological elements and design process which can stimulate human emotion, this study is to analyse it as a base of emotional design. This study aims to present characteristics of space image for space realization which meets the age of smart technology in terms of unifying smart space with emotional design, focusing on four future housing galleries shown by construction companies. First, the study speculated smart space in theory and classified characteristics and types of smart space into connectivity, sensitivity, reiteration and variability according to changes in space paradigm. Second, the study identified the background and main points emotional design appeared, analysed types of smart space based on characteristics of experimentation, connectivity and symbolism and speculated characteristics of emotional design in each type. In respect to characteristics of emotional design in smart space, organic connection and sensitivity are remarkably presented through experimentation and reiteration is presented through organic connection and experimentation, and variability through symbolism and experimentation.

• Journal of Advanced Marine Engineering and Technology
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• v.9 no.1
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• pp.61-73
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• 1985

The induction motor is widely used in the power equipments of the ship and the various industrial drive applications because it is robust and relatively simple and cheap to manufacture, but it has a disadvantage that the speed of induction motor is not controlled in wide range such as d.c motor. In this paper, the characteristics relating to the Kramer system that the speed of three phase wound type induction motor is controlled by changing the exciting e.m.f. of the secondary circuit is described. In order to analyze the characteristics, a new simplified and approximated T-type equivalent circuit from the Kramer circuit with three phase graetz connection and d.c machine is proposed. The stator current, motor torque and mechanical output power are computed by the current, torque and power equations derived by its equivalent circuit. Through the experiments, the $I_f-N$, torque-slip and current-slip characteristic curves of the tested motor are obtained and the various needed constants are determined. The numerical values obtained from the above method are compared with experimental values under the same conditions. As a result of the above investigation, it is found that the induction motor speed by the Kramer system is controlled by 28 per cent under the rated speed by changing the field current of d.c motor and the values computed by the current and torque equations derived by the simplified and approximated T-type equivalent circuit generally come to approach the experimental values.

• The Journal of Advanced Prosthodontics
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• v.10 no.2
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• pp.155-162
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• 2018

PURPOSE. The aim of this study was to compare the fracture of implant component behavior of external and internal type of implants to suggest directions for successful implant treatment. MATERIALS AND METHODS. Data were collected from the clinical records of all patients who received WARANTEC implants at Seoul National University Dental Hospital from February 2002 to January 2014 for 12 years. Total number of implants was 1,289 and an average of 3.2 implants was installed per patient. Information about abutment connection type, implant locations, platform sizes was collected with presence of implant component fractures and their managements. SPSS statistics software (version 24.0, IBM) was used for the statistical analysis. RESULTS. Overall fracture was significantly more frequent in internal type. The most frequently fractured component was abutment in internal type implants, and screw fracture occurred most frequently in external type. Analyzing by fractured components, screw fracture was the most frequent in the maxillary anterior region and the most abutment fracture occurred in the maxillary posterior region and screw fractures occurred more frequently in NP (narrow platform) and abutment fractures occurred more frequently in RP (regular platform). CONCLUSION. In external type, screw fracture occurred most frequently, especially in the maxillary anterior region, and in internal type, abutment fracture occurred frequently in the posterior region. placement of an external type implant rather than an internal type is recommended for the posterior region where abutment fractures frequently occur.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.33.1-33.1
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• 2010

We investigate the relation between the presence of bars in galaxies and AGN activities. Bars are believed to play an important role in fueling of AGN. Although there have been many previous studies on this topic, "the AGN-Bar Connection" is still an open question. To better understand the connection, we use a volume-limited sample of 9,726 late-type galaxies brighter than $M_r$=-19.5+5logh at $0.02{\leqq}z{\leqq}0.05489$, drawn from SDSS DR7. Among galaxies in the sample, 1,963 galaxies are classified as AGN-host galaxies based on the emission-line ratios while barred galaxies are identified by visual inspection. The bar fraction in AGN host galaxies (22.5%) is 3-times higher than in star-forming galaxies (8.6%). However, this trend is simply caused by the fact that the bar fraction increases with galaxy mass or luminosity and that AGN host galaxies are on average more massive than star-forming galaxies. Nevertheless, we find that among AGN host galaxies, the bar fraction increases with the Eddington ratio $(L_{[OIII]}/M_{[BH]})$, and this trend remains intact even at fixed galaxy luminosity and stellar velocity dispersion. These results imply that bars play a role in triggering AGNs.