• The Journal of Advanced Prosthodontics
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• v.10 no.5
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• pp.381-387
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• 2018

PURPOSE. Cement-retained implant prostheses can lack proper retrievability during repair, and residual cement can cause peri-implantitis. The purpose of this in vitro study was to evaluate the influence of abutment height and convergence angle on the retrievability of cement-retained implant prostheses with lingual slots, known as retrievable cement-type slots (RCS). MATERIALS AND METHODS. We fabricated six types of titanium abutments (10 of each type) with two different heights (4 mm and 6 mm), three different convergence angles ($8^{\circ}$, $10^{\circ}$, and $12^{\circ}$), a sloped shoulder margin (0.6 mm depth), a rectangular shape ($6mm{\times}6.5mm$) with rounded edges, and a rectangular ledge ($2mm{\times}1mm$) for the RCS. One monolithic zirconia crown was fabricated for each abutment using a dental computer-aided design/computer-aided manufacturing system. The abutments and crowns were permanently cemented together with dual-curing resin cement, followed by 24 hours in demineralized water at room temperature. Using a custom-made device with a slot driver and torque gauge, we recorded the torque ($N{\cdot}cm$) required to remove the crowns. Statistical analysis was conducted using multiple regression analysis and Mann-Whitney U tests (${\alpha}=.05$). RESULTS. Removal torques significantly decreased as convergence angles increased. Multiple regression analysis showed no significant interaction between the abutment height and the convergence angle (Durbin-Watson ratio: 2.186). CONCLUSION. Within the limitations of this in vitro study, we suggest that the retrievability of cement-retained implant prostheses with RCS can be maintained by adjusting the abutment height and convergence angle, even when they are permanently cemented together.

• Journal of Korean Academy of Nursing
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• v.22 no.3
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• pp.389-406
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• 1992

This study was designed to identify nursing students' attitudes toward life through a Q-methodology. A Q-sample was formed through a review of the literature and interviews(n＝160)l The final Q-sample consisted of 37 statements out of an initial 100 statements after consultation with an expert panel and pilot testing. The P-sample consisted of 14 university nursing students and 27 junior college nursing students, which was selected by convenience sampling method. Data were analyzed by the Q-analysis method. The correlation between type 2 and type 3 was relatively high (r＝0.539) ; that between type 1 and type 3 was lowest (r＝0.014). The first type of attitude was the “rational utilitarian” type. Students in this type valued life relative to the quality of life. They agreed with euthanasia and artificial abortion if the quality of life was threatened. The criteria for their judgement were scientific knowledge and rationality. The second type of attitude was the “Christian deontologic” type. These students appreciated the sanctity of life according to Christian dogma. They disagreed with euthanasia and artficial abortion. And they disagreed strongly that life should be created by scientific development, because only God creates life. The third type of attitude was the “unconditional deontologic” type. These students agreed with the sanctity of life, not from Christian belief but from belief in the sanctity of life. The final type of attitude was the “prima facie(conditional) deonologic” type. These students appreciated the value of life and humanity. They expressed concern for others' life and suffering. They do not want to afflict others with their own miseries. This group showed a dual value system toward themselves and others. So they experience conflict between their concern for their on and others' conditions. These nursing students' values may have been influenced by their clinical experience in hospitals and other nursing fields. Through this study, we may realize the importance of education in nursing ethics for discussion of ethical conflicts and to support ethical nursing practice.

• Journal of Advanced Navigation Technology
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• v.15 no.2
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• pp.326-333
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• 2011

In the present study, we measured the performance (accuracy and reaction time) of the user in the virtual environment with see-through Head-Mounted Display system that includes 3D sound generated through Head-Related Transfer Function (HRTF) to investigate the feasibility of auditory display for a certain object's spatial information. To sum up the results of two experiments, when presenting location information of the object with 3D sound, it is desirable that information arrangement from the user should be an orthogonal pattern which is located with right angle, not a diagonal pattern. Like these results propose that spatial information presentation with 3D sound make the optimal object arrangement of virtual environment possible.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1901-1907
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• 2015

Today's smartphones and user devices are equipped with multiple radio interfaces increasingly. Aggregating theses multiple radio interfaces and using them concurrently will increase a user's communication speed immediately, but at the expense of increased power consumption. In this paper, we develop a mathematical performance model of an adaptive radio activation scheme by which a radio interface is activated only when needed for performance increase and deactivated otherwise. The developed model shows that the adaptive scheme reduces delay significantly and almost halves power consumption below a certain level of traffic input.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.7
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• pp.1344-1349
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• 2012

The Korean DGPS station transmits the 200 bps GPS enhancement signal using the MSK modulation in frequency range of 283.5 kHz to 325 kHz. The land-based stations of 6 sites provide the service area of 80 km with the output power of 500 W. The ocean-based stations of 11 sites provide the output power of 300 W, which provide the DGPS service to 185 kM. Some places are serviced from two or three DGPS stations. The interferences among the DGPS stations using the high power can be occurred. Also, the performances of the user terminasl in dual service area can be degraded. In this paper, the protection ratios for the DGPS service are defined. Using the MF wave propagation model, the interferences among the DGPS stations and the adjacent wireless ground stations are analyzed. Also, the performances of DGPS user terminals are analyzed in the viewpoint of interference.

• Journal of Navigation and Port Research
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• v.34 no.10
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• pp.775-780
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• 2010

In the machinery, the brake system is as important part as machine's working. The situation of emergency stop, the machine doesn't stopped would be occur big accident. This is common things for all of machinery, also for the ships. There are two kind of mooring devices are existed on the ship. One of them, the windlass winch, is used to anchor. The other, the mooring winch is used to moor the ship in pier use the rope tied to bitt on dock. In case of previously been used mooring winch made of a steel plate, and the bolt which was connect brake band and lining broken. In this study, prevent an accident find the position of stress concentration by finite element analysis program. And removed stress concentration. And search the optimum position of the separation angle to be more efficient.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.7
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• pp.1544-1550
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• 2013

In recent years, Container Security Device(CSD) using GPS & GLONASS to improve logistics efficiency are being extensively researched. The purpose of this paper is to examine the performance development antenna usable cargo container security transport. Antenna developed by study were optimized to match logistics environment apply to GPS/GLONASS dual frequency for monitering system. The measure of antenna have confirmation about frequency characteristics each 1575.42MHz, 1602MHz and VSWR is 2:1 measured in return loss -9.54dB. Reliability of this antenna has been verified about GPS/GLONASS through test-operation between the south korea and Russia.

• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.34-41
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• 2005

We report some recent results in the rewritable Blu-ray Disc with enhanced overwrite cyclability by using the growth dominant eutectic based Ge(Sb70Te30)+Sb recording layer, GeN interface layer and write strategy optimization. We have developed phase-change optical media with appropriate write strategy for 36(i.e., 1X)-72Mbps(i.e., 2X) dual speed Blu-ray Disc system and fur the future high speed optical data storage. For recording layer, eutectic-based Ge(Sb70Te30)+Sb material was used and Sb/Te ratio and Ge content were optimized to obtain proper erasability and archival stability of recorded amorphous marks. The recording layer is wrapped up in GeN interface layers to obtain overwrite cyclability and higher crystallization speed. In addition, we designed appropriate write strategy so called Time-Shifted Multipulse (TSMP) write strategy where starting position of multipulse parts are shined from reference clock. With this write strategy, the jitter characteristics of the disc was improved and we found that leading edge jitter was improved much more than trailing edge jitter in 1X-2X speed recording. Finally, we investigated the higher speed feasibility of 144Mbps(i.e., 4X) by adopting some elemental doping to the eutectic based Ag-In-Sb-Te recording layer and structural optimization of constitution layers in Blu-ray Disc. In the paper, we report the effect of Sn addition for the feasibility of higher speed recording. The addition of Sn shows increases of the crystallization speed of phase change recording layer.

• Ocean and Polar Research
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• v.34 no.3
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• pp.349-364
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• 2012

This study focuses on systematic structure of factors, which affect commercialization of ocean science and technology (OST), applying both grounded theory methodology (GTM) and semantic network analysis methodology (SNAM) by using in-depth interviews with 8 specialists previously experienced in the same field. This study further focuses on clarification of the distinctiveness and universality of commercialization factors on OST by comparatively analyzing on the commercialization factors of general sciences and technologies. Using SNAM, it was determined that commercialization success required connected support system, government support, technology marketing, technology power and characteristics of commercialized entities, which were identified as dominant factors. GTM presented an outcome that connected support systems among participants in commercialization and found that research institute strategies are significant factors in the core phenomenon of commercialization, while technology marketing, technology power and market-oriented technology are important conditions. In addition, the factors of technology, market, connection of participants and government support of commercialized entities are shown as equally important factors for commercialization of ocean science and technology. Secondly, SNAM results indicate that ocean science characteristics depend on a network of government support, research institute strategy, organization and manpower, capital power, and technology marketing, as these ocean science characteristics have been identified as significant factors in the GTM study. It has been determined that technology, market and government support should be connected in order for commercialization of ocean science and technology (OST). Moreover, commercialization methods, applied to the marketing of commercialization of ocean science and technology is differentiated from others since commercialization success is more relevant to these factors.

• Asian Journal of Atmospheric Environment
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• v.5 no.1
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• pp.8-20
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• 2011

Atmospheric visibility is one of the indicators used to evaluate the status of air quality. Based on a conceptual definition of visibility as the maximum distance at which the outline of the selected target can be recognized, an image analysis technique is introduced here and an algorithm is developed for visibility monitoring. Although there are various measurement techniques, ranging from bulk and precise instruments to naked eye observation techniques, each has their own limitations. In this study, a series of image analysis techniques were introduced and examined for in-situ application. An imaging system was built up using a digital camera and was installed on the study sites in Incheon and Seoul separately. Visual range was also monitored by using a dual technology visibility sensor in Incheon and transmissometer in Seoul simultaneously. The Sobel mask filter was applied to detect the edge lines of objects by extracting the high frequency from the digital image. The root mean square (RMS) index of variation among the pixels in the image was substantially correlated with the visual ranges in Incheon and Seoul with correlations of $R^2$=0.88 and $R^2$=0.71, respectively. The regression line equations between the visual range and the RMS index in Incheon and Seoul were VR=$2.36e^{0.46{\times}(RMS)}$ and VR=$3.18e^{0.15{\times}(RMS)}$, respectively. It was also confirmed that the fine particles ($PM_{2.5}$) have more impacts to the impairment of visibility than coarse particles.