• The Journal of Korean Academy of Prosthodontics
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• v.39 no.3
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• pp.243-249
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• 2001

Statement of the problem. The interest in all-ceramic restorations has increased as more techniques have become available. With the introduction of machinable dental ceramics and CAD/CAM systems or Copy-milling systems there is a need for evaluating the quality levels of these new fabrication techniques. Purpose. This study was to evaluate the fitting accuracy of machined all-ceramic crowns made out of an industrially prefabricated feldspathic porcelain. Material and Methods. Three master models with different cutting depth (0.8mm/1.0mm/1.2mm)were produced using a palladium-silver alloy. A total of 36 working dies, 12 of each form, was used for the modellation of prototype resin copings and 36 additional crowns, 12 of each cutting depth, were produced by using the $CEREC^{(R)}2$ system for all crowns. The maginal fit of all 72 crowns was then evaluated on their respective master die at 54 circularly staggered points of measurement per crown under a fixation pressure of 30 N by using a computerized video image system. Results. The medians of the copy-milled $CELAY^{(R)}$ crowns ranged from 29 to $36{\mu}m$. The highest value for the marginal gap was found in group B (cutting depth 1.0mm) at $107{\mu}m$. The median for the $CEREC^{(R)}2$ crowns was found between 43.5 and $70{\mu}m$. The maximum values for all three groups ranged from $181{\mu}m$ to $286{\mu}m$. With $286{\mu}m$ the highest value for marginal gap was found in group C. the Kruskal-Wallis test and multiple comparisons analysis procedure revealed a significant influence of the production technique on the marginal fit in all three groups (p<0,02). Conclusion. 1. The $CELAY^{(R)}$ system is capable to produce all-ceramic crowns with a significantly better marginal fit than the $CEREC^{(R)}2$ system. 2. As far as premolar crowns produced with the $CEREC^{(R)}2$ system are concerned, the cutting depth has a significant influence on fitting accuracy. 3. The production of crowns with an acceptable marginal fit is possible with both systems. However, adhesive luting is recommended for milled feldspathic porcelain crowns.

• Journal of Periodontal and Implant Science
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• v.42 no.6
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• pp.204-211
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• 2012

Purpose: This study was performed to establish an experimental rabbit model for single-stage maxillary sinus augmentation with simultaneous implant placement. Methods: Twelve mature New Zealand white rabbits were used for the experiments. The rabbit maxillary sinuses were divided into 3 groups according to sinus augmentation materials: blood clot (BC), autogenous bone (AB), and bovine-derived hydroxyapatite (BHA). Small titanium implants were simultaneously placed in the animals during the sinus augmentation procedure. The rabbits were sacrificed 4 and 8 weeks after surgery and were observed histologically. Histomorphometric analyses using image analysis software were also performed to evaluate the parameters related to bone regeneration and implant-bone integration. Results: The BC group showed an evident collapse of the sinus membrane and limited new bone formation around the original sinus floor at 4 and 8 weeks. In the AB group, the sinus membrane was well retained above the implant apex, and new bone formation was significant at both examination periods. The BHA group also showed retention of the elevated sinus membrane above the screw apex and evident new bone formation at both points in time. The total area of the mineral component (TMA) in the area of interest and the bone-to-implant contact did not show any significant differences among all the groups. In the AB group, the TMA had significantly decreased from 4 to 8 weeks. Conclusions: Within the limits of this study, the rabbit sinus model showed satisfactory results in the comparison of different grafting conditions in single-stage sinus floor elevation with simultaneous implant placement. We found that the rabbit model was useful for maxillary sinus augmentation with simultaneous implant placement.

• Journal of the Korean Home Economics Association
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• v.40 no.12
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• pp.85-108
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• 2002

The objectives of this study were to investigate the trend of the attitude and the behavior about consumer's internet premium advertisement and its application and the factors which influence on the attitude and the behavior about consumer's premium advertisement and its application; the demographic variables, internet communication-environment variables and variables in relation to consumer's premium advertisement application. For these purpose, the data collected two way: internet survey and questionnaire survey. The data used in this study included people who have looked an internet Premium Advertisement more than once during internet use. Major findings were as following: (1) The attitude of internet premium advertisement and its application could be described as the mean 34.16 md 24.61 separately(3.11 and 2.73 point on 5.00 points scale). The behavior of application about internet premium advertisement was measured as a behavior of application whether or not; application 18.7% and unapplication 81.3%. (2) The attitude of application about internet premium advertisement was significantly different according to age, joining frequency on internet, past experience of winning a premium, purchasing information search, interesting connection on the internet, the risk about the money loss and negative evaluation of other persons, the economical values of premiums, winning possibility, and preferable premiums. The behavior of application about internet premium advertisement, the behavior of application whether or not was significantly different according to sex, age, school career, a circuit speed, a period of using, joining frequency and a using place, past experience of winning a premium, purchasing information search, interesting connection on the internet, the risk about the negative evaluation of other persons, the economical values of premiums, winning possibility, and preferable premiums. (3) When looking at the influence of variables about the attitude of application about internet premium advertisement, the most influence variables was the past experience of winning a premium, and next was winning possibility, sex, the interest about the premiums which made the consumer want to apply, the economical values of premiums, the purpose of purchase information search and the using time. The explanation of those variables were 22.6%. As the result of the Logistic analysis, it was found that the frequency of the internet connection, the past experience of winning premiums, the risk about the outflow of credit information, interesting premiums, and premium advertisement were the most important variables to affect the possibility of the behavior of application about internet premium advertisement critically.

• Journal of Families and Better Life
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• v.29 no.4
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• pp.109-123
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• 2011

The importance of finance in our society is truly absolute, and the of financial consumers who cope with the financial environment is becoming. Recently, many authorities in Korea to perceive the absence of serious economic or financial consumer education in order to find a fundamental solution for such a phenomenon, there is a growing need to introduce financial consumer education. This study aims to review the comprehension power of finance among consumers are college students in this society the importance of finance is becoming greater, and to a way promote financial consumer education by analyzing the demand level for The main results obtained from the include the following. First, as a result of reviewing the characteristics of respondents, their average age was 21.8 years old, and on average they each had 4.16 credit cards. Most of them had no experience of receiving financial consumer education in their teenage years, and their interest level in investment was shown to be above average. Second, as a result of reviewing their comprehension power of finance, it was shown to be 64.10 points on average their comprehension of the income area was the highest, their comprehension money management was shown to be the lowest. Third, as a result of reviewing the perception level of the provision of financial consumer education, it was shown to be very low the perception level of on-line and off-line financial consumer education provided by the YMCA was shown to be the highest. Fourth, as a result of reviewing the level financial consumer education, it was shown to be very high. For the level for institutions financial consumer education, financial institutions the highest. For the level for the method of financial consumer education, respondents chose practical experience the most and education books the least. For the intention of participating in financial consumer education, most respondents that they would participate, and most of them answered that the starting period should be the teenage years and childhood Therefore, as a result, most university student's consumers have concerned on financial education and financial inportance, it need to educate for the university student's consumers, and it need to develop technical tools and contents for ficancial education.

• Spatial Information Research
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• v.15 no.3
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• pp.267-278
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• 2007

Internationally many models are developed and applied to predict the impact of the climate change, as occurring a lot of symptoms by climate change. Also, in Korea, according to increasing the application of the climate effect model in many research fields, it is required to study the method for preparing climate data and the characteristics of the climate. In this study IDSW (Inverse Distance Squared Weighting), one of the spatial statistic methods, is applied to interpolate. This method estimates a point of interest by assigning more weight to closer points, which are limited to be select by 3 in 100 km radius. As a result, annual average temperature and precipitation had increased by $0.4^{\circ}C$ and 412 mm during 1977 to 2006. They are also predicted to increase by $3.96^{\circ}C$, 319 mm in the 2100 compared to 2007. High variability of temperature and precipitation for last 30 years shows in some part of the Gangwon-do and in the southern part of Korea. Besides in the study of the variable trend, the variability of temperature and precipitation is inclined to increase in Gangwon-do and southern east part, respectively. However, during 2071 to 2100 variability of temperature is predicted to be high in midwest of Korea and variability of precipitation in the east. In the trend of variability, variability of temperature is apt to increase into west south, and variability of precipitation increase in midwest and a part of south.

• Journal of Korean Home Economics Education Association
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• v.21 no.4
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• pp.145-158
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• 2009

The purpose of this study was to find out how much home economics(HE) textbook was focused on what kind of factors in career education, by analyzing the HE textbooks from the 7th grade(1st grade of the middle school) to the 10th grade(1st grade of high school), which were developed by applying the 7th educational process. 12 textbooks which were published by three publishers were randomly selected by grade. This study used the instrument developed by Korea Research Institute for Vacational Education & Training(2001) as an analysis frame, along with a content analysis system. The results of this study were as follows. The publishers of HE textbook stressed similar points in each section of career education, evenly reflecting the objectives and contents of career education. Three kinds of publishers also placed the same weight on the factors of career education in each unit, and suggested the contents related to career education in the whole units. HE textbook was designed to lead learners to understand self and have interest in varied occupations. Additionally, it provided the learners with a chance to consider their career and occupation by means of detailed job information, and its contents including learning of occupational ability for job selection were useful to plan and prepare for career. Accordingly, as HE textbook is most effective to promote connection between work and learning and contains proper factors of career guidance, it is one of the most appropriate textbooks to deal with career education.

• 한국지구과학회:학술대회논문집
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• 2005.02a
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• pp.203-212
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• 2005

The purpose of this study was to develop e-learning contents and to examine how ICT-powered instruction using the developed e-learning contents affects the science achievements of students and how the students respond to that. After an experiment in the 7th class of the weather condition unit in high school earth science, e-learning contents were prepared by using the videotaped material and flash animation to teach key learning points. The selected two different classes, experimental and control groups, shows almost the same final scores in the first semester. The experimental group received ICT-powered instruction with the contents developed in the study, and the control group received a typical expository lesson. And then the achievement test was done to these two groups, separately. The major findings of the study were as follows: As for the effects of ICT-powered instruction on the academic achievement, the average scores of the experimental group is higher than that of the control group, but the difference is insignificant. When each group was subdivided into the upper and lower groups, the upper group got higher average scores and the difference was significant. But there was no significant disparity between the lower groups. Therefore, the ICT-powered instruction using the e-learning contents gives a good effect on the students whose levels are higher than the average. In the questionaike about the ICT instruction, they generally had a positive opinion about its impact on learning interest and class participation and its learning effects.

• Proceedings of the Korean Fiber Society Conference
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• 1990.06b
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• pp.36-37
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• 1990

In the past, facile dissolution of cellulose has been hampered by the lack of suitable nondegrading solvents. Recently, this problem has been solved in our laboratory by the discovery of an inexpensive, convenient solvent system, that is the mixture of $NH_3\;and\;NH_4SCN$, for cellulose. Also, the $cellulose/NH_3/NH_4SCN$ solution system has been found to form the anisotropic, i.e., liquid crystalline phase. It is believed that both the cholesterio and the nematic phase occur. This finding has prompted extensive on-going researoh on the formation of the liquid crystalline phase from an inexpensive natural source such as cellulose since the nematic phase is envisioned as an excellent precursor sources for products with desirable properties, for example, high modulus and high strength. This interest naturally leads to a desire to understand the theological properties of the nematic phase so that the transformation of the nematic phase to the solid state with desirable properties can be efficiently accomplished, ;From this point of view, the theological behavior of the $cellulose/NH3_/NH_4SCN$ system has been studied as a function of shear rate and shear stress over a wide range of solvent compositions, cellulose concentration, centrifugation and urea contents, Results indicate that the viscosity decreases with increasing shear rate. A marked shear thinning behavior and a quasi-Newtonian behavior were observed in the low shear rate region and in the high shear rate region, respectively for all solvent compositions. The $cellulose/NH_3/NH_4SCN$ solution system only exhibited the viscosity increase with increasing cellulose concentration and failed to show the viscosity drop generally observed at the point of incipience of liquid crystal formation, This may be due to the gel-like nature of the solution by the association of the rodlike molecules into bundles which may serve as crosslinking points giving the cellulose solution a network structure. Also, simply hydrogen bonding may be so restrictive of molecular mobility that a viscosity drop is blocked. In addition to the above results, yield stress and thixotropy were also observed in the $cellulose/NH_3/NB_4SCN$ solution system which are characteristics of liquid crystal and gel, The results of the effect of centrifugation on viscosity show that viscosity decreases by the application of centrifugation. This may be explained by the change of the piled polydomain structure to the dispersed polydomain structure due to the pressure gradient generated during centrifugation.ation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.15-31
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• 2013

This paper proposes an intermediate image generation method for the viewer's view point by tracking the viewer's face, which is converted to a digital hologram. Its purpose is to increase the viewing angle of a digital hologram, which is gathering higher and higher interest these days. The method assumes that the image information for the leftmost and the rightmost view points within the viewing angle to be controlled are given. It uses a stereo-matching method between the leftmost and the rightmost depth images to obtain the pseudo-disparity increment per depth value. With this increment, the positional informations from both the leftmost view point and the rightmost view point are generated, which are blended to get the information at the wanted intermediate viewpoint. The occurrable dis-occlusion region in this case is defined and a inpainting method is proposed. The results from implementing and experimenting this method showed that the average image qualities of the generated depth and RGB image were 33.83[dB] and 29.5[dB], respectively, and the average execution time was 250[ms] per frame. Also, we propose a prototype system to service digital hologram interactively to the viewer by using the proposed intermediate view generation method. It includes the operations of data acquisition for the leftmost and the rightmost viewpoints, camera calibration and image rectification, intermediate view image generation, computer-generated hologram (CGH) generation, and reconstruction of the hologram image. This system is implemented in the LabView(R) environments, in which CGH generation and hologram image reconstruction are implemented with GPGPUs, while others are implemented in software. The implemented system showed the execution speed to process about 5 frames per second.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.997-1005
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• 2010

Recently, there has been a growing interest in the use of WLAN technology due to its easy deployment, flexibility and so on. Examples of WLAN applications range from standard internet services such as Web access to real-time services with strict latency/throughput requirements such as multimedia video and voice over IP on wireless network environments. Fair and efficient distribution of the traffic loads among APs(Access Points) has become an important issue for improved utilization of WLAN. This paper focuses on an AP selection scheme for achieving better load balance, and hence increasing network resource utilization for each user on wireless network environments. This scheme makes use of active scan patterns and the network delay as main parameters of load measurement and AP selection. This scheme attempts to estimate the AP traffic loads by observing the up/down delay and utilize the results to maximize the link resource efficiency through load balancing. We compared the proposed scheme with the original SNR(Signal to Noise Ratio)-based scheme using the NS-2(Network Simulation.2). We found that the proposed scheme improves the throughput by 12.5% and lower the network up/down link delay by 36.84% and 60.42%, respectively. All in all, the new scheme can significantly increase overall network throughput and reduce up/down delay while providing excellent quality for voice and video services.