• The Journal of Korean Academy of Prosthodontics
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• v.49 no.4
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• pp.316-323
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• 2011

Purpose: The purpose of this study was to investigate the effect of different thread designs on the marginal bone stresses around dental implant. Materials and methods: Standard ITI implant(ITI Dental Implant System; Straumann AG, Waldenburg, Switzerland), 4.1 mm in diameter and 10 mm in length, was selected as control. Test implants of four different thread patterns were created based on control implant, i.e. maintaining all geometrical design of control implant except thread pattern. Four thread designs used in test implants include (1) small V-shape screw (model A), (2) large V-shape screw (model B), (3) buttress screw (model C), and (4) trapezoid screw (model D). Surface area for unit length of implant was 14.4 $mm^2$ (control), 21.7 (small V-shape screw), 20.6 (large V-shape screw), 17.0 (buttress screw) and 28.7 $mm^2$ (trapezoid screw). Finite element models of implant/bone complex were created using an axisymmetric scheme with the use of NISA II/DISPLAY III (Engineering Mechanics Research Corporation, Troy, MI, USA). A load of 100 N applied to the central node on the crown top either in parallel direction or at 30 degree to the implant axis (in order to apply non-axial load to the implant NKTP type 34 element was employed). Quantification and comparison of the peak stress in the marginal bone of each implant model was made using a series of regression analyses based on the stress data calculated at the 5 reference points which were set at 0.2, 0.4, 0.6, 0.8 and 1.0 mm from implant wall on the marginal bone surface. Results: Results showed that although severe stress concentration on the marginal bone cannot be avoided a substantial reduction in the peak stress is achievable using different thread design. The peak marginal bone stresses under vertical loading condition were 7.84, 6.45, 5.96, 6.85, 5.39 MPa for control and model A, B, C and D, respectively. And 29.18, 26.45, 25.12, 27.37, 23.58 MPa when subject to inclined loading. Conclusion: It was concluded that the thread design is an important influential factor to the marginal bone stresses.

• Journal of Soil and Groundwater Environment
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• v.10 no.4
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• pp.1-12
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• 2005

Policies regarding to soil quality of the United States, the United Kingdom, the Netherlands, Germany, and Demark were analyzed to suggest Korean policy for improving soil quality concept and it's implementation. All countries met four criteria: I) Soil quality levels of contaminants are indebt to concept of contaminant risk to recipients (human and ecosystem); ii) Any soil quality value can't be a magic number to determine whether a site is contaminated or not. To determine risk of sites, risk assessment of the sites should be followed; iii) Concentrations of contaminants of sites are not always significantly certain to risk of human and ecosystem of the sites; and iv) Soil quality levels are adopted based on land uses and plans. Considering our rooms to improve policies and analysis of the other country reports on their legislations about soil quality levels, our policy implementation could be approached from these directions: i) Our concept for soil quality levels needs to develop in scientific and rational. ii) Soil quality levels and risk assessment should be implemented as determining tools of site contamination in parallel, and iii) Soil quality levels depending on land uses and plans should be developed in debt with rational and scientific concept of risk. Increasing efficacy of Korea policy regarding the soil quality levels would be in dept to applying concepts of SCL (Soil Contamination Level) and SRL (Soil Regulatory Level) developed, implementing soil quality levels and risk assessment of contaminated sites in conjunction, and classifying three distinctions of land uses based on sensitiveness of recipients (human and ecosystem) to contaminants in soil in this research.

• The Korean Journal of Petroleum Geology
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• v.10 no.1_2 s.11
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• pp.23-33
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• 2004

The Lago Sofia conglomerate in southern Chile is a lenticular unit encased within mudstone-dominated, deep-sea successions (Cerro Toro Formation, upper Cretaceous), extending from north to south for more than $120{\cal}km$. The Lago Sofia conglomerate is a unique example of long, gravelly deep-sea channels, which are rare in the modern environments. In the northern part (areas of Lago Pehoe and Laguna Goic), the conglomerate unit consists of 3-5 conglomerate bodies intervened by mudstone sequences. Paleocurrent data from these bodies indicate sediment transport to the east, south, and southeart. The conglomerate bodies in the northern Part are interpreted as the tributary channels that drained down the Paleoslope and converged to form N-S-trending trunk channels. In the southern part (Lago Sofia section), the conglomerate unit comprises a thick (> 300 m) conglomerate body, which probably formed in axial trunk channels of the N-5-trending foredeep trough. The well-exposed Lago Sofia section allowed for detailed investigation of sedimentary facies and large-scale architecture of the deepsea channel conglomerate. The conglomerate in Lago Sofia section comprises stratified conglomerate, massive-to-graded conglomerate, and diamictite, which represent bedload deposition under turbidity currents, deposition by high-density turbidity currents, and muddy debris flows, respectively. Paleocurrent data suggest that the debris flows originated from the failure of nearby channel banks or slopes flanking the channel system, whereas the turbidity currents flowed parallel to the orientation of the overall channel system. Architectural elements produced by turbidity currents represent vertical stacking of gravel sheets, lateral accretion of gravel bars, migration of gravel dunes, and filling of channel thalwegs and scoured hollows, similar to those in terrestrial gravel-bed braided rivers. Observations of large-scale stratal pattern reveal that the channel bodies are offset stacked toward the east, suggestive of an eastward migration of the axial trunk channel. The eastward channel migration is probably due to tectonic tilting related to the uplift of the Andean protocordillera just west of the Lago Sofia deep-sea channel system.

• (The) Research of the performance art and culture
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• no.37
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• pp.187-221
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• 2018

The style of performance to contemporary nongak is not fixed in a specific period of time, but in conjunction with the total change in society that has occurred during its long time from traditional society to the modern times. It is important to recognize that the traditional performance art forms that we see and feel today, including nongak, are constantly interacting with the times and are a change in the design that has been shaped in the past. Now, we must get rid of the negative idea that there is some fixed prototype in Nongak. Also, the value and the need for preservation of current Nongak should not be evaluated according to the ' pure genealogy of village descent, ' which was possible only in villages with small population movements long ago. If can get rid of the stereotypes, can greatly expand the view that we read the values of a certain Nongak. Looking away from a few of these traditional fixed perceptions can significantly broaden the view of reading the winning values of some farmers ' songs. In this regard, this report determined the performing style and nature of Changwon's Toichon-noangak through a structural analysis of the Toichon-noangak in contemporary, and discussed the significance of the transmittion of Toichon-noangak. Changwon Toichon Nongak started out as an even-present ritual performance based on the religious nature of the village community and actively exchanged with the economic, social and cultural foundations of the Republic of Korea, which began to accumulate in the modern changes. Generally, the performance style of village Nongak has a combination of characteristics according to the ritual, Dure(collective labor), entertainment, and these three functions. Toichon Nongak is also a village Nongak style and in which of ritual nongak and village entertainment nongak are connected in parallel as one in the big total structure. The origin, background, purpose, and style of towing of Toichon noangak demonstrates that the Toichon noangak is originally ceremonial noangak derived from a prayer style of Dongje. Then, various factors influences are interacting with Toichon noangak within the orbit of modern society, such a style of playing, popular nongak, is believed to have undergone an extended change. Overall, Toichon nongak performance style can be called nongak, which maintains traditional customs and it also has the changed characteristics according to the times of village society.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.2
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• pp.173-180
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• 2021

Purpose: The purpose of this study was to evaluate the retentive characteristics of the additional attachments used with implant bar attachment under repeated insertion/removal cycles. Materials and methods: The newly developed attachment and the commercially available attachment were investigated: ADD-Lock (AL), Locator blue (LB). Two fixtures were placed parallel to each other on the custom lower mounting, and patrix of each attachment was fixed to the fixture. Also, the matrix of each attachment was placed on the opposing upper mounting. A universal testing machine was used to measure the retentive force during initial, 100, 250, 500, 1000, 2000, and 2500 repeated insertion/removal cycles. Wear and deformation of the attachment s were observed by scanning electron microscopy (SEM). Mann-Whitney U test (α=.05) and wilcoxon signed-rank test (α=.05) were performed to compare retentive force between each group and before and after 2500 repeated insertion/removal cycles. Results: In terms of initial retentive force and retentive force after 2500 repeated insertion/removal cycles, the AL group (15.24 ± 1.46 N and 9.74 ± 1.16 N) showed significantly smaller values than the LB group (43.53 ± 12.39 N and 22.99 ± 4.77 N) (P<.05). Also, in the loss of retentive force, the AL group (5.50 ± 1.08 N, 36.08%) showed a smaller value than the LB group (20.54 ± 11.89 N, 47.19%) (P<.05). Based on SEM analysis, The AL group showed noticeable wear and deformation in the patrix and the LB group in the matrix. Conclusion: Locator showed a higher initial retentive force than newly developed attachment, while the loss of retentive force was also higher. Both additional attachments are considered to have sufficient retentive force after repeated insertion/removal cycles.

• Korean Journal of Mineralogy and Petrology
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• v.34 no.3
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• pp.193-208
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• 2021

The characteristics of the microcrack lengths(①), microcrack spacings(②) and Brazilian tensile strengths(③) related to the six directions of rock cleavages(H2~R1) in Geochang granite were analyzed. First, the 18 cumulative graphs for the above three major factors representing unique characteristics of the rock cleavages were made. Through the general chart for these graphs classified into three planes and three rock cleavages, the 28 parameters on the length, spacing and Brazilian tensile strength have been determined. The results of correlation analysis among these parameters are summarized as follows. Second, the above parameters were classified into six groups(I~VI) according to the sorting order on the magnitude of parameter values among three rock cleavages and three planes. The values of parameters belonging to group I and II are in order of R(rift) < G(grain) < H(hardway) and H < G < R. The values of the 8 parameters on the length of line(os₂, 𝚫s, 𝚫L and oS^mean), the exponent(λ_L^mean and λ_S^mean), the slope(a^mean) and the anisotropy coefficient (An^mean) are in order of R < G < H and H'(hardway plane) < G'(grain plane) < R'(rift plane). Third, the noticeable differences in distribution patterns among the six types of charts for three planes and three rock cleavages are as follows. From the chart for three planes, the values of 𝚫L, 𝚫s and 𝚫σ_t, corresponding to the distance between two points where the two fitting lines meet on the X-axis, increase in the order of R' < H' < G'. In particular, the two graphs of R2 and G2 related to the length and Brazilian tensile strength are almost parallel to each other and show the distribution characteristics of hardway plane. Among the graphs related to the Brazilian tensile strength, the overall shape for hardway plane is similar to that for grain. From the chart for three rock cleavages, the slopes of the graphs related to the length increase in the order of R < G < H, while those of the graphs related to the spacing and Brazilian tensile strength decrease in the order of R < G < H. Lastly, the characteristics of variation among the six rock cleavages, the three planes and the three rock cleavages were visualized through the correlation chart among the above parameters from this study.

• Korean Journal of Poultry Science
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• v.49 no.4
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• pp.287-298
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• 2022

This study evaluated the efficacy of chlorine dioxide (ClO₂) as an oxidant to reduce malodor emission from chicken feces. Two experiments were performed with the following four treatments in parallel: 1) fresh chicken feces with only distilled water added as a control, 2) a commercial germicide as a positive control, and 3) 2,000 or 4) 3,000 ppm of ClO₂ supplementation. Aluminum gas bags containing chicken feces sealed with a silicone plug were used in both experiments, and each treatment was tested in triplicate. In Experiment 1, 10 mL of each additive was added on the first day of incubation, and malodor emissions were then assessed after 10 days of incubation. In Experiment 2, 1 mL of each additive was added daily during a 14-day incubation period. At the end of the incubation, gas production, malodor-causing substances (H₂S and NH₃ gases), dry matter, pH, volatile fatty acids (VFAs), and microbial enumeration were analyzed. Supplementing ClO₂ at 2,000 and 3,000 ppm significantly reduced the pH and the ammonia-N, total VFA, H₂S, and ammonia gas concentrations in chicken feces compared with the control feces (P<0.05). Additionally, microbial analysis indicated that the number of coliform bacteria was decrease after ClO₂ treatment (P<0.05). In conclusion, ClO₂ at 2,000 and 3,000 ppm was effective at reducing malodor emission from chicken feces. However, further studies are warranted to examine the effects of ClO₂ at various concentrations and the effects on malodor emission from a poultry farm.

• Journal of Venture Innovation
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• v.5 no.1
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• pp.59-73
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• 2022

Untact marketing is being activated due to COVID-19. As a result, live commerce, an untact seller, is also active in the e-commerce market. Therefore, in this study, we tried to find out what factors influence consumers when they purchase through live commerce. In particular, since consumers' trust and flow in live commerce platforms and products is important, their mediating effects were analyzed. The research model was established by deriving common variables among the characteristics of live commerce based on previous studies. An online survey was conducted for empirical analysis. 200 users who made at least one purchase in live commerce were analyzed. The study results are as follows. Among the characteristics of live commerce, entertainment, economics, professionality were found to have a positive (+) effect on purchase intention. On the other hand, ease of use did not significantly affect purchase intention. The influence was shown in the order of entertainment, professionality and economics. The mediating effect of trust was found to play a mediating role in that entertainment, economics, and professionality affect purchase intention. On the other hand, a significant mediating effect was not tested between ease of use and purchase intention. As for the mediating effect of flow, it was found that flow plays a mediating role in that entertainment and economics affect purchase intention. On the other hand, the mediating effect of flow in terms of ease of use and economics affecting purchase intention was not tested. As for the multiple mediating effect of flow and trust, the mediating effect of flow was stronger than the mediating effect of trust when entertainment had an effect on purchase intention. In terms of professionality affecting purchase intention, the mediating effect of flow was also stronger than the mediating effect of trust. On the other hand, it was analyzed that only trust had a mediating effect when economics had an effect on purchase intention. The results of this study empirically tested that entertainment, which is a fun and interesting factor of live commerce content, is the most important factor when consumers use live commerce. In addition, various results were derived, such as cases where trust and flow act as mediators at the same time or not at all. Practical implications can be found in that it provided a clue about what to prioritize in order to reach consumers for live commerce platform.

• Korean Journal of Ecology and Environment
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• v.56 no.3
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• pp.187-195
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• 2023

Almost all of the water from agricultural dams located to the upper of the Yeongsan river is supplied as irrigation water for farmland and thus is not discharged to the main stream of the river. Also, most of the irrigation water does not return to the river after use, adding to the lack of flow in the main stream. As a result, the water quality and aquatic health of the river have become the poorest among the four major rivers in Korea. Therefore, in this study, several strategies for water quality improvement of the river were developed considering pollution reduction and flow rate increase, and their effect analysis was performed using a water quality model. The results of this study showed that the target water quality of the Yeongsan river could be achieved if flow increase strategies (FISs) are intensively pursued in parallel with pollution reduction. The reason is because the water quality of the river has been steadily improved through pollution reduction but this method is now nearing the limit. In addition, rainfall-related FISs such as dam construction and water distribution adjustment may be less effective or lost if a megadrought continues due to climate change and then rainfall does not occur for a long time. Therefore, in the future, if the application conditions for the FISs are similar, the seawater desalination facility, which is independent of rainfall, should be considered as the priority installation target among the FISs. The reason is that seawater desalination facilities can replace the water supply function of dams, which are difficult to newly build in Korea, and can be useful as a climate change adaptation facility by preventing water-related disasters in the event of a long-term megadrought.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.6
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• pp.13-24
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• 2022

The purpose of this study is to examine whether the existence of related personnel in KOSDAQ technology special listed firms has a signal effect on the market and affects performance when listed. The KOSDAQ technology special listing system is a system introduced to enable future growth by securing financing through corporate public offering based on the technology and marketability of technology-based startups and venture companies. As a result of analyzing 135 special technology companies listed from 2005 to 21 (excluding SPAC mergers and foreign companies) whether or not related personnel affect corporate value and listing period when they are listed, it was analyzed that the presence of related personnel did not significantly affect corporate value or listing period. The same was found in the results of the verification by reducing the scope to related personnel such as public officials and related agencies. However, under certain conditions, significant results were derived from the presence of related personnel on the listing of companies listed in special technology cases. It was found that the presence of related personnel and VC investment had a significant effect on corporate value, and in the case of bio-industry, there was a slight significant effect on the duration of listing. This study is significant in that it systematically analyzed the signal effect of the existence of related personnel for the first time for all 135 companies. In addition, as a result of the analysis, the results suggest that internalized efforts to secure technology and marketability are more important, such as parallel to VC investment, rather than simply recruiting related personnel.