• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.1
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• pp.41-47
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• 2020

Purpose: The purpose of this study was to evaluate the flexural strength and reliability of highly translucent colored zirconia for all ceramic restoration. Materials and Methods: Bar-shaped specimens (25 × 4 × 2.5 mm) were prepared from highly translucent monolithic zirconia. Three experimental groups were set up according to color (shade A0, A1, and A3). For each group, 20 specimens were prepared. Flexural strength was determined using a 3-point flexural test and results were analyzed with one-way ANOVA test. Weibull statistical analysis provided 2 parameter estimates: Weibull modulus and characteristic strength. X-ray diffraction (XRD) analysis was performed. Results: There was statistically significant difference between uncolored (Shade A0) and colored (shade A1 and A3) (P < 0.05), but there was no difference between colored groups (P > 0.05). The uncolored group had higher reliability compared with colored study groups. On x-ray diffraction analysis of each group, typical peaks of tetragonal phase appeared in all groups. Conclusion: Within the limitations of this in vitro study, coloring highly translucent zirconia had significant effect on flexural strength and reliability. Therefore, clinicians should be careful when using highly translucent colored zirconia to prevent breakage of veneering ceramic and enhance aesthetics.

• Journal of Internet Computing and Services
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• v.12 no.4
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• pp.35-43
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• 2011

Cognitive Radio (CR) ad hoc network is highly considered as one of promising future ad hoc networks, which enables opportunistic access to under-utilized licensed spectrum. Similarly to other CR networks, the spectrum sensing is a prerequisite in CR ad hoc network. Collaborative spectrum sensing can help increasing sensing performance. For such an infrastructureless network, however the coordination for the sensing collaboration is really complicated due to the lack of a central controller. In this paper, we propose a novel collaborative spectrum sensing scheme in which the final decision is made by the node with the highest data reliability based on a sequential Dempster Shafer theory. The collaboration of sensing data is also executed by the proposed contention-aware reporting mechanism which utilizes the sensing data reliability order for broadcasting spectrum sensing result. The proposed method reduces the collecting time and the overhead of the control channel due to the efficiency of the ordered sequential combination while keeping the same sensing performance in comparison with the conventional cooperative centralized spectrum sensing scheme.

• Journal of Korean Society of Forest Science
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• v.103 no.2
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• pp.278-286
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• 2014

Forestry management problems in South Korea have been caused by small and scattered forest lands, aging forest owners, and the increase of absentee forest owners. To solve these problems, it is a time to consider the introduction of forest land bank system for the expansion of forestry management scale, the effective management of neglected forest lands, and the stable livelihood support for aged forest owners. Therefore, this research implemented the questionnaire survey of necessity, expectation, willingness to use, and introduction plans for the forest land bank system in order to examine the feasibility and demand of the system focused on forest owners, non-forest owners, and people who return to the farm. The questionnaire survey was conducted for 262 of resident forest owners, 152 of absentee forest owners, 427 of non-forest owners, and 101 of people who return to the farm. 77.5% of forest owners and 63.8% of non-forest owners agreed with the necessity of the introduction for the forest land bank system. Both forest owners and non-forest owners would prefer to use forest land reverse mortgage and leasing among projects of the forest land bank. In addition, 75% of people who return to the farm also expected that forest land bank would be helpful to their rural and mountain life, and they would have higher preference to participate in leasing and buying forest lands than other projects. Based on the outputs of the feasibility and demand survey in this research, this study can play a key role in determining basic direction, major functions, types and range of projects as well as providing information for establishing policies of the forest land bank system.

• Science of Emotion and Sensibility
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• v.16 no.2
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• pp.195-206
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• 2013

The main causes of traffic accidents while driving a car is of the driver's visual distraction. In this study, the color sensitivity of the information projected on the windshield were evaluated for HUD (Head Up Display) system which helps the driver's eyes on the road while driving. The driving Information were projected $9^{\circ}$ downward from front sight $0^{\circ}$ under lab's fluorescent lights, LED floorlights and the TV had having 25 [lux] illumination when driving at night environment and 100,000 [lux] of daylight environment. Munsell color hue of the basic five colors (R, Y, G, B, P) and the color of traffic lights YR, W were the color of the seven characters, each character were outlined by White, Gray except for W. Total of 19 experimental stimuli was shown in the environment of day and night driving for asking visibility information of color, fatigue, preferences, and evaluate the degree of interference. The results came out that the bright Y and G color is visibility significantly for daylight. Second, with the outline of the text, the color of the outline works as a background for luminance contrast effects and affects visibility. Third, without the outline, the glass in front of the vehicle acts as the background and the luminance contrast of characters achieve greater brightness and visibility. The luminance contrast between the stimuli and background should be considered for increasing color visibility for driving information which is an important factor for HUD commercialization.

• Science of Emotion and Sensibility
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• v.21 no.2
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• pp.29-42
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• 2018

As information technology is more actively incorporated into automobiles, the role of IVIS (In-Vehicle Infotainment System) is becoming increasingly important for providing convenience and entertainment for drivers. However, using the infotainment systems while driving requires task switching and attending to two visual resources simultaneously. We simulated a setting where participants have to drive while interacting with the infotainment system and examined how task difficulty and motor cues impact driver task-switching and driving performance, specifically whether the effects of motor cues differ depending on task difficulty. For the infotainment display, we used two types of number array depending on the congruency between the digit repetition and the chunking unit, while task difficulty was manipulated by the size of the touch-keys. Participants were instructed to dial two numbers on the screen while we recorded the dialing time, lateral position, inter-key press intervals, and steering wheel control. We found that dialing time and lateral position were affected by task difficulty, while the type of number array had no effect. However, the inter-key press intervals between chunked numbers and steering wheel movement both increased when participants had to use an incongruent number array, which indicates that, if number digits are repeated, chunking is ignored by the drivers. Our findings indicate that, in a dual-task condition, motor cues offset the effect of chunking and can effectively signal the timing for task switching.

• Journal of The Korean Association For Science Education
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• v.18 no.1
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• pp.35-42
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• 1998

To investigate 13 year old pupils' suggested aims, recognition of relevant variable, and the relationship between the suggested aim and the conclusion which is drawn by pupils, we classified experiments in textdbook into three cases: (1) Case involving dependent variable and independent variable in the title of experiment, (2) Case involving dependent variable only, where pupils can know independent variable from the content of textbook, (3) Case involving dependent variable only, where pupils hardly can know independent variable from the content of textbook. In respect of the aims which pupils suggested, the suggested aims were reduced to the title of experiment in case(1). However, the suggested aims were divided into several forms which is not relevant to the content of experiment in case (2), (3). This shows that pupils are affected by the title of experiment according to how the variable is involved in the title of experiment. This is supported by the fact that when the variable is described in the title, the suggested aim is reduced to the title of experiment. On the other hand, there was a relationship between the suggested aim and the drawn conclusion in case (1). But there was few relationships in case (2) and (3). Surprisingly, the drawn conclusion in case(1) was not consistent with the expected one because of the inappropriate experimental setting. We need to be more careful in experimental setting, pupils' cognitive ability, and openness of experiment to help pupils perform experiment successfully.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.4
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• pp.371-392
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• 2011

The purpose of this study was to comparatively analyze the stress distribution according to the inclinations of abutments and angulations of the implant fixtures under occlusal loading force. Three study models with straight and $15^{\circ}$ and $25^{\circ}$-angled abutments were prepared following the insertion of Implants parallel to the long axis of the tooth. Additional two experimental models were fabricated with $15^{\circ}$ and $25^{\circ}$ fixture inclinations. Using ANSYS 11, a finite element analysis program, the magnitudes of stress distribution were analyzed. The magnitude of stress under loading was lowest when the load was applied vertically onto the axis of implant. And the magnitude of stress under compound(vertical+oblique) loading was increased as the inclination of implant abutment and fixture was increase. But, the distribution of stress was different as the loading conditions, because of the horizontal offset. As the offset between the axis of loading and the central axis of the implant increased, the stress was increased.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.3
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• pp.255-265
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• 2009

Recently many studies have been published on application of immediate loaded implants. However, the immediate loading protocol has not been well documented. The purpose of the present study was to evaluate the stress distribution between bone-implant interfaces and the effect of implant length in the anterior maxilla using 3 dimensional finite element analyses. The diameter 4.0 mm threaded type implants with different length(8.5 mm, 10.0 mm, 11.5 mm, 13.0 mm, 15.0 mm) were used in this study. The bone quality of anterior maxillary bone block was assumed to D3 bone. Bone-implant interfaces of immediately loaded implant were constructed using a contact element for simulating the non osseointegration status. For simplification of all the processing procedures, all of the material assumed to be homogenous, isotropic, and linearly elastic. The 178 N of static force was applied on the middle of the palatoincisal line angle of the abutment with $120^{\circ}$ angle to the long axis of abutment. Maximum von Mises stress were concentrated on the labial cortical bone of the implant neck area, especially at the cortical-cancellous bone interfaces. Compared the different length, highest peak stress value was observed at the 8.5 mm implants and the results indicated a tendency towards favorable stress distribution on the bone, when the length was increased. Presence of cortical bone was very important to immediate loading, and it appears that implants of a length more than 13 mm are preferable for immediate loading at the anterior maxilla.

• The Journal of the Korea Contents Association
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• v.10 no.3
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• pp.294-300
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• 2010

With the development of media technology, UCC actively working through the medium of the Net, the Internet space, which can influence politics instead of TV is drawing attention as the new leading media. As the one-sided media influence of TV is dwindling in the times of the Internet, the hegemony of the media is rapidly changing into UCC marked by two-way interaction. Especially, UCC has the characteristic that it has changed the people performing a role as the receptor of the media into the agent of enormous political influence as well as the freshness specific to its contents. This study was intended to investigate the types of diverse political influences of UCC in political practice as well as daily politics with a focus on the fact that it can newly project the world led by the media and their changes and exercise strong power in changing the society. Therefore, it attempted to investigate the political influence and ripple effect that UCC can exert by attempting to analyze what political influence UCC can exercise at diverse political situations including election. As a result, UCC led to four situations such as incentive-exploding type, issue-leading type, dispersion-switching type, direction-obeying type. This can be said to lead to the positive effect at the political field, such as implementing direct democracy through digital technology.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.85-100
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• 2010

Devonian Cairn Formation is one of the important hydrocarbon reservoirs in Alberta, Canada. However, the Cairn Formation, outcropped in the study area, is not prospective reservoir with poor porosity and permeability by some late diagenetic processes. In this study, geochemical characteristics of the Cairn Formation were studied to use these preliminary results for advanced geological and geophysical petroleum explorations in the near future. Rock-Eval pyrolysis showed that total organic carbon content is less than 0.3 wt.%, indicating a minor amount of bitumen and/or other hydrocarbons. The carbonates in the Cairn Formation are mainly composed of subhedral and anhedral dolomites. Pore sizes in the carbonate are various, ranging from nanometer to micrometer. Clastic sediments increase in the upper and lower parts of the Cairn Formation, probably due to changing its depositional conditions. The Cairn Formation can also be divided into several intervals based on Ca/Mg ratio in dolomite and degree of amount of calcite. These could be formed by different sedimentary environment, degree of cementation and recrystallization, different saline/fresh water, etc.