• The Journal of Korean Academy of Prosthodontics
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• v.51 no.4
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• pp.245-251
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• 2013

Purpose: This study was conducted to compare in vivo biofilm formation on titanium surface and zirconia surface. Materials and methods: For biofilm formation on titanium and zirconia in oral cavity, after producing oral appliances using acrylic resin and orthodontic wire tailored to 9 subjects, we made titanium and zirconia specimens ($6mm{\times}6mm{\times}2mm$), fixed them on oral appliances and maintained them in oral cavity of test subjects for 24 and 72 hours. Test subjects who have equipped two pairs of specimens maintained oral hygiene not by using toothpaste but only by tooth brushing. After 24 and 72 hours, we removed and observed specimens through scanning electron microscopy (SEM). Results: Biofilm formation showed large deviation depending on individuals. For formation comparison between titanium and zirconia for 24 hours, zirconia showed less biofilm formation than titanium. Biofilm formation showed large deviation depending on individuals. As for formation comparison between zirconia and titanium, the degree of biofilm formation in zirconia was less than it was in titanium after a lapse of 24 hours. The result of biofilm formation in 72 hours trial show that zirconia has an inclination to formate less biofilm than it was in titanium. Conclusion: Based on the above results, we can conclude that early biofilm formation in oral cavity was influenced by difference of abutment materials.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.1645-1651
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• 2015

This paper describes the changes of shape accuracy in workpiece materials depending on the turning clearance angle. The experiments started from choosing three workpiece materials, SM45C(machine structural carbon steel), STS303(stainless steel) and SCM415 (chrome-molybdenum steel). The experiments showed specifically how features of selected materials changed when they were processed with diverse machining depths, 0.1 mm, 0.2 mm and 0.3 mm, with various negative angles, $0.0^{\circ}(-6.0^{\circ})$, $0.3^{\circ}(-6.3^{\circ})$ and $0.9^{\circ}(-6.9^{\circ})$, and called cutting edge inclination starting from a fixed rotational speed, 2,500 rpm, focusing on the feed rate, 0.07 mm/rev and 0.10 mm/rev. The results of the accuracy of processing, cylindricity, deviation from coaxiality, etc. were compared using the graph and table. The accuracy of cylindricity in the order of degree $0.0^{\circ}{\rightarrow}0.3^{\circ}{\rightarrow}0.9^{\circ}$ depending on the workpiece materials showed the best cylindricity when it was $0.9^{\circ}$. In conclusion, the accuracy improved in specific degrees irrespective of the quality of the materials when the bite negative angles increased. This means that workability improved in these experiments. In addition, the processing shape changed depending on depth of the cut and feed rate.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.6
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• pp.847-854
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• 2003

In general cooked rice would be used as a major raw material for making Takju. In this case quality, taste and storage time of Takju were not fully satisfied. Fermentation conditions for Takiu mash were examined by using the germed brown rice in this study. In case of the germed brown rice on 2nd stage mash, alcohol was slowly generated in comparison with the cooked rice. Reducing sugar was slowly produced and the amount of reducing sugar was low. The sugar content was created at a uniform rate. The pH was shown to be higher in mash of the germed brown rice than that of the cooked rice. Acidity change showed a similar inclination to pH change. The degree of yeast growth on the mash of the germed brown rice was revealed to be slightly lower than that of the cooked rice. Temperature of mash was kept to be constant after 3 days from fermentation. Fusel oil produced from the mash of the germed brown rice was less gernerated in comparison with the cooked rice. Amount of amino acid in case of the germed brown rice was indicated to be higher. Takju made with the germed brown rice was shown to be 1.3 times in overall taste, 1.5 times in refreshing as compared with Takju made with the cooked rice. However there are no differences between them in flavor and color of Takju. In overall acceptance Takju made with the germed brown rice was shown to be 1.3 times as compared with Takju made with the cooked rice. In conclusion the germed brown rice was expected to be able to be better in Takju quality.

• Journal of Navigation and Port Research
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• v.37 no.5
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• pp.551-557
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• 2013

In this paper, we manufactured portable inflatable kayak using ultra high pressure drop stitch. by improving inflatable kayaks' performance with a design using the extra-high-voltage special space paper, they were manufactured to go near to performance of hard shell kayaks. The kayaks were manufactured having all merits of the performance of hard shell kayaks and functionality and portability of the inflatable kayaks, and through performance evaluation of test products, the performance was compared with previous hard shell kayaks. About 6 knot of target speed in the verification result of resistance performance, the developed kayak was more excellent than the HOBIE-KONA kayak by 12.33%. In case of same displacement in a result of inclination test, the centroid of the developed kayak was less distributed by 22.7% than the HOBIE-KONA kayak, based on the bottoms of the ships. This makes the difference for righting arm (GZ) lessened to some degree because the developed kayak is lower than the HOBIE-KONA kayak in the centroid. In the dynamic stability of ship bodies, the HOBIE-KONA kayak showed a little excellent performance. However, in rudder force and resistance factor, the developed kayak was more outstanding than the HOBIE-KONA kayak.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.69-76
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• 2018

The present study analyzed the effect of film hole position of 45 degree ribbed cooling channel on film cooling performance of gas turbine blades. We also investigated the influence of the ribs under the fixed blowing ratio. Three-dimensional numerical model was constructed and extensive simulation was conducted using the commercial code (Fluent ver. 17.0) under steady-state condition. Base on the simulation results, We investigated the cooling effectiveness, flow velocity, streamline, and pressure coefficient. Moreover, We analyzed the effect of cooling hole position on ejection of the secondary flow caused by the rib structure. From the results, It was found that internal flow of the cooling channel forms a vortex pair in the counterclockwise from the top side, and clockwise from the bottom side. For the channels with ribs, the vortex flow generated by the ribs caused a higher pressure difference near the hole outlet, resulting in at least 12% higher cooling effectiveness than the channel without ribs. Additionally, when the hole is located on the left side of the ribbed channel (Rib-Left), it can be found that the secondary flow generated by the ribs hits against wall surface near the hole to form a flow in the direction of the hole inclination angle. Therefore, It is considered that the region where the cooling gas discharged to the blade surface stays in the main flow boundary layer is wider than the other cases. In this case, The largest pressure coefficient difference was observed near the outlet of the hole, and as a result, the discharge of the cooling gas was accelerated and the cooling efficiency was slightly increased.

• Journal of Conservation Science
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• v.29 no.3
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• pp.223-229
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• 2013

It is not known in details for the A.D. period as the archaeomagnetic dating method to be fully facilitated in Korea but it has prepared for the revised shape of standard curve to trace the geomagnetic field variation, and there were cases to increase the survey on relics on the B.C. period to find out for the detailed archaeomagnetic field variation on the Bronze Age to the Early Iron Age. Furthermore, the survey cases on the relics on the Neolithic Age began to emerge a little by little archaeomagnetic field variation of the Neolithic Age through 34 pieces of the archaeomagnetic measurement data as making active advancement around mid-western region. Data is insufficient yet that it is difficult to find out the detailed trend of modification but it is estimated for approximate appearance. The archaeomagnetic field variation of the Neolithic Age made changes without breaking away from the scope of changes in the A.D. period as in the same way with the Bronze Age, and comparing to the variation of archaeomagnetic field for the Bronze Age, the magnetic inclination shifted within the scope of having almost no difference, but the declination is shown to skewed toward the east in its overall appearance. In addition, the comparison was made with the data of the Jomon Age in Japan and the archaeomagnetic measurement data of Korea has a little bit more depth for while the declination is skewed toward the east for 10 degree or more compared to those of Japan. However, in the part where the data is concentrated most intensely, the data for both countries has significant part to overlap to each other that the archaeomagnetic field variation of the Neolithic Age of Korea showed overall similar variation with certain partial changes when compared to those of Japan.

• Journal of Distribution Science
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• v.11 no.10
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• pp.107-116
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• 2013

Purpose - Eggs are nutritionally complete and one of the most popular natural foods. Moreover, the poultry industry is one of the important food industries. However, early industrialization of the poultry industry on its own did not lead to further development compared to other livestock industries. In this study, we investigate what factors influence consumers' behavior and how consumers' understanding of retail business affects their propensity to consume. This study is different from other studies as it analyzes how the brand names of manufacturers and distribution companies affect the purchasing characteristics or actual purchase behavior of consumers in order to suggest how these manufacturers and distribution companies can increase their competitiveness. Research design, data, methodology - This study conducted a survey of 250 randomly selected egg purchasers in discount stores from January to April 2013. Consumers' purchase tendencies were calculated through frequency analysis. This result was then utilized using cluster analysis to draw a conclusion about which purchase tendency influenced consumers buying three different brands of eggs or whether this tendency really affected consumers. As a result, the outcomes of Hypotheses 2 and 3 were not clear so we drew a conclusion with our analysis of Hypothesis 1. Results - While the outcomes of Hypotheses 2 and 3 did not clearly indicate whether purchasing tendencies affected consumers when buying eggs, our analysis of Hypothesis 1 indicated that consumers were affected by the quality of the eggs rather than exterior factors such as the brand name. Thus, we concluded that it is important to promote the excellence of the quality of the eggs. Usually firms buy eggs from farms and repackage them in order to sell them. In this sense, if consumers were aware of this egg production process, and eggs were fairly distributed to retailers, large retail PB businesses would also be able to enhance their competitiveness. Conclusions - The brand, packaging, retail outlet, and other external features influenced the purchase of eggs to a certain degree, while shelf life, grade of the eggs, cleanliness, and other intrinsic characteristics had more influence. In particular, shelf life was the most important factor influencing purchase. Consumers were influenced not only by intrinsic characteristics of the eggs but also by large-scale producers' brands. Consumers relied upon the brand despite reduced competition because they found it difficult to identify shelf life and/or cleanliness. Small businesses and/or large-scale retailers can remain competitive by maintaining the freshness and cleanliness of the eggs. Further studies need to investigate areas in which consumers' cognition of the product is poor and/or the purchase inclination with regard to less developed industries such as eggs. In this study, the greatest problem was that consumers did not consume in accordance with the current situation as consumers have preferred fresh and clean eggs for a long time compared to purchase decisions based on external brands and/or packaging.

• Journal of Astronomy and Space Sciences
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• v.20 no.1
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• pp.21-28
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• 2003

In case that we independently obtain orbital informations about the low earth satellites of foreign countries using radar systems, we develop the orbit determination algorithm for this purpose using a SGP4 model with an analytical orbit model and the extended Kalman filter with a real-time processing method. When the state vector is Keplerian orbital elements, singularity problems happen to compute partial derivative with respect to inclination and eccentricity orbit elements. To cope with this problem, we set state vector osculating to mean equinox and true equator cartesian elements with coordinate transformation. The state transition matrix and the covariance matrix are numerically computed using a SGP4 model. Observational measurements are the type of azimuth, elevation and range, filter process to each measurement in a lump. After analyzing performance of the developed orbit determination algorithm using TOPEX/POSEIDON POE(precision 0.bit Ephemeris), its position error has about 1 km. To be similar to performance of NORAD system that has up to 3km position accuracy during 7 days need to radar system performance that have accuracy within 0.1 degree for azimuth and elevation and 50m for range.

• The Journal of Engineering Geology
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• v.10 no.2
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• pp.18-35
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• 2000

The most dominant type of landslide in Korea is debris flows which mostly take place along mountain slopes during the rainy season, July to August. The landslides have been reported to begin activation when rainfall is more than 200mm within 2days. The debris flows are usually followed by translational slips which occur upper part of mountain slopes and they transit to debris flow as getting down to the valleys. Lithology, location, slope inclination, grain size distribution of soil, permeability, dry density and porosity have been proved as triggering factor causing translational slides. The triggering data taken from mapping are statistically analysed to get landslide potential quantitatively. Rock mass creeps mostly occur on well bedded sedimentary rocks in Kyeongsang Basin. Although the displacement of rock mass creep is relatively small about 1m, the creep can cause severe hazards due to relatively large volume of the involved rock mass. Examples are rock mass creep occurred in the mouth of Hwangryongsan Tunnel, in Chilgok and in Sachon in 1999. Although the direct factor of the creeps are due to slope cutting at the foot area, more attention is required A rotational slide occurring within thick soil formation or weathered rock is also closely related to bottom part of slope cutting. It is propagated circular or semi-circular type. Especially in korea, the rotational slide may be frequently occurred in Tertiary tuff area. Because they are mainly composed of volcanic ash and pyroclastic materials, well developed joints and high degree of swelling and absorption can easily cause the slide. The landslide among the Pohang-Guryongpo national road is belong to this type of slide.

• Korean Journal of Veterinary Research
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• v.39 no.6
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• pp.1081-1090
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• 1999

To establish the protocol of a standardized exercise test for evaluating exercise intolerance and degree of fitness in Thoroughbred racehorses, we examined serum lactate concentrations related to exercise intensities using the high speed treadmill. Twelve clinically healthy Thoroughbred racehorses with or without previous training or racing history were assigned to two gorups, fit and unfit group, respectively. The protocol used for the standardized exercise test was consisted of two stages : stage of warm-up and that of acceleration. During the warm-up, the horses exercised 5 min at 1.8m/s and 3 min 3.4m/s without inclination. At the acceleration stage, exercise test was performed at 10% slope and the speed was increased from the initial 5m/s to the maximal speed which each tested horse could keep up with. The speed was increased with incremental steps of 1 m/s every minute. During the last 15 sec of each step, blood samples were collected for serum lactate determination. $V_{max}$(maximal treadmill speed which tested horses could keep up with) of the fit group ($10.93{\pm}0.33m/s$, mean${\pm}$SE, n = 6) was higher than that of the unfit group ($9.52{\pm}0.23m/s$, mean${\pm}$SE, n = 6). Serum lactate concentrations increased exponentially according to exercise intensities. $V_{La4}$(speed producing a serum lactate concentration of 4mmol/l) of the fit group, $6.45{\pm}0.26m/s$, was higher than that of the unfit group, $5.45{\pm}0.23m/s$. $La_{peak}$(peak plasma lactate concentration during the exercise test) was lower in the fit group ($20.34{\pm}1.62mmol/l$ at 1 min after maximal intensity exercise) than in the unfit group ($24.78{\pm}1.09mmol/l$ at 2 min after maximal exercise step). $t_{50%}$(time required for the recovery of lactate concentration to be one-half of $La_{peak}$ after maximal exercise) of the unfit group and the fit group were 40.0 and 18.0 min, respectively. Therefore, the protocol of the incremental standardized exercise test utilized in this study seems to be reliable for the assessment of fitness and exercise intolerance for the Thoroughbred racehorses.