• Journal of The Korean Society of Grassland and Forage Science
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• v.35 no.2
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• pp.99-104
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• 2015

This study was conducted to evaluate on agronomic characteristics, dry matter (DM) and digestible dry matter (DDM) yields of summer sowing sorghum hybrids (Sorghum bicolor (L) Moench) at Seongju in Gyeongbuk from 2013 to 2014. The experiment was arranged in randomized complete block design with three replications. Sorghum hybrids were seeded $31^{st}$ of July, 2013 and 2014. Sorghum hybrids were harvested on $3^{rd}$ November, 2013 and $5^{th}$ November, 2014. The observed average heading date was October 5, 8 and 9 for Sordan79, Sprint and SX17 respectively. The DM yield of 'SX17', 'Sordan79', and 'Sprint' was 24.2, 23,9 and 23.4 ton/ha, respectively and DM yield of those were significantly higher (p<0.05) than other three cultivars in 2013. DM yield of 'SX17', 'Sprint' and 'Sordan79' was 20.8, 20.0 and 19.3 ton/ha, respectively and DM yield of those was significantly higher (p<0.05) than other three cultivars in 2014. The DDM yield of 'SX17', 'Sordan79', and 'Sprint' was also higher (p<0.05) than other three cultivars in 2013 and 2014. ADF content of sorghum hybrids was low, whereas DDM was high. The results of this study indicated that traditional sorghum-sudangrass hybrids ('SX17', 'Sordan79') and sudan grass-sudangrass hybrid ('Sprint') than late flowering sorghum-sudangrass hybrid ('PACF8350') and sorghum-sorghum hybrids ('SS405', 'Sugar grazer') would be recommended for DM and DDM yields in the southern Korea.

• Journal of the Korea Convergence Society
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• v.10 no.2
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• pp.301-307
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• 2019

The purpose of this study is to evaluate the lap time of K-1 sprint competition and compare the records of the best group and the other groups. Based on these data we are willing to provide them on pace control strategies for improving their performances. The analysis was conducted on 12 elite kayak players, measuring the lap time by every interval after dividing the entire 1,000-meter race into 10 sections of 100 meters. We divide the group A, B, C and D based on their final time records. Two-factor repeated measures ANOVA, One-way ANOVA, and correlation analysis were performed. There were no significant lap time differences in the section of first 200m and last 200m between A, B and C. But the C's lap time of 200m~600m were significantly later than group A and B. Non-superior athletes need to establish strategies to reduce lap time in the middle section.

• Korean Journal of Applied Biomechanics
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• v.27 no.3
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• pp.219-227
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• 2017

Objective: The aim of this study was to analyze the effects of bobsleigh shoes on the lower extremity range of motion and start speed lap time and to develop bobsleigh shoes suitable for winter environments and Korean players based on sports science and optimized biomechanical performance. Background: The bobsleigh shoes used in the start section of the sport are one of the most important equipment for improving athletes' performances. Despite the importance of the start section, there are no shoes that are specifically designed for Korean bobsleigh athletes. Thus, Korean athletes have to wear sprint spike shoes instead of bobsleigh shoes to practice the start. Method: The subjects included four bobsleigh athletes from the Gangwon Province Bobsleigh Skeleton Federation. The study selected the bobsleigh shoe type A (company A) and type B (company B). We analyzed the lower extremity range of motion and sprint time (start line to 10 m) using a Motion Analysis System (USA). Results: In the measurement of the time required for the bobsleigh start section (10 m), the type A shoes demonstrated the fastest section record by $2.765{\pm}0.086sec$ and yielded more efficient movements, hip and knee flexion, hip extension, ankle dorsiflexion, plantar flexion, and inversion than the type B shoes. Conclusion: Type A shoes can yield a better performance via effective lower extremity movements in the bobsleigh start section. Application: In the future, functional analysis should be conducted by comparing the upper material properties, comfort, and muscle fatigue of bobsleigh shoes based on the Type A shoes to develop such shoes suitable for Koreans.

• Korean Journal of Applied Biomechanics
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• v.26 no.3
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• pp.315-321
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• 2016

Objective: The aim of this study was to analyze effects of the toe-spring angle of bobsleigh shoes on start speed lap time to develop Korean-specific bobsled shoes suitable for winter environments and for domestic players on the basis of sports science and optimized biomechanical performance. Method: Seven Korean bobsleigh athletes participated in this study, with three pairs of sprint spikes from three companies (Type A, Type B, Type C). To analyze sprint lap time and forefoot bending angle for each shoe, participants were instructed to drag a sled 15 meters from the start line at a maximum sprint. forefoot bending angle was collected by a high speed camera, and lap time speed was measured. Results: Lap time for type B shoes was $3.52{\pm}0.17sec$, type A was $3.55{\pm}0.19sec$, and type C was $3.56{\pm}0.18sec$. Forefoot bending angles were: angle 1, $6.88{\pm}5.55^{\circ}$; angle 2, $9.23{\pm}6.38^{\circ}$; angle 3, $15.56{\pm}5.39^{\circ}$; angle 4, $9.54{\pm}3.85^{\circ}$; angle 5, $9.22{\pm}5.08^{\circ}$; angle 6, $7.66{\pm}6.44^{\circ}$; and angle 7, $4.30{\pm}6.24^{\circ}$ (p<.001). Forefoot bending in angle 3 was as follows: type A, $16.47{\pm}6.01^{\circ}$; type B, $14.30{\pm}4.96^{\circ}$; and type C, $15.90{\pm}5.17^{\circ}$. Conclusion: Hard outsoles and midsoles are better than soft type for reduced start lap time when developing a prototype Korean bobsled shoe.

• Journal of the Korea Convergence Society
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• v.10 no.8
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• pp.277-282
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• 2019

This study was conducted to compare the lap time of high school boys' K-2 1000m final at the $99^{th}$ National Sports Festival with the lap time of the World Championship final held in 2018 and to find an optimal pacing strategy to enhance the performance. The high school boys' average final record was 242.89 seconds, and the top international's 199.58 seconds. There was 43 seconds difference in records and by lap-time it were 9, 12, 9, and 13 seconds behind every 250m. World Championship players used the Super Fast-Even Pacing-Even Pacing-Spurt strategy. The $1^{st}$ to $3^{rd}$ ranked high school boys used Slow-Fast-Super Slow-Super Fast strategy, and $4^{th}$ to $9^{th}$ ranked boys used Fast-Slow-Fast-Slow strategy. The high school boys need to modify their pacing strategies to achieve world-class performance.

• Korean Journal of Applied Biomechanics
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• v.27 no.4
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• pp.239-245
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• 2017

Objective: The bobsleigh shoes used in the start section are one of the most important equipment for improving the competition. Despite the importance of the start section, there are no shoes that are specific for bobsleigh athletes in Korea and Korean athletes have to wear sprint spike shoes and practice the start instead of wearing bobsleigh shoes. The objective of the present study was to provide data for improving the performance of Korean bobsleigh athletes by investigating the differences in their split time, plantar pressure, and forefoot bending angle based on skill levels at the start of a run under the same conditions as training conditions. Method: Six Korean bobsleigh athletes were divided into two groups, superior (n=3) and non-superior (n=3). A digital speedometer measured the split time at the start; the Pedar-X system (Novel, Germany) measured plantar pressure. Plantar pressures and split times were measured as the athletes pushed a bobsleigh and sprinted at full speed from the start line to the 10-m mark on the bobsleigh track. An ultra-high-speed camera was used to measure the forefoot bending angle during the start phase. Results: Significant between-group differences were found in split times (p<.000; superior = 2.38 s, non-superior = 2.52 s). The superior group had a larger rearfoot (p<.05) contact area, maximum rearfoot force (p<.01), and a larger change in angles 3 and 4 (p<.05). Conclusion: At the start of a bobsleigh run, proper use of the rearfoot for achieving effective driving force and increasing frictional resistance through a wider frictional force can shorten start time.

• Korean Journal of Computational Design and Engineering
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• v.22 no.2
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• pp.215-221
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• 2017

This paper describes a method of precise estimation for printing time and material consumption which are directly related to the 3D printing cost. Printing process and head motion of 3D printers using digital printing head, which is analyzed by its digitized steps, is rapidly simulated without slicing to calculate estimated printing results. Using this method, printing time and material usage of 3D printer were estimated quickly and precisely and compared to the real printing result. Applying compensation using the printing parameters, transferred from the 3D printer to the printing estimation system, even more accurate estimation is achieved. This method is used in the 3D Sprint software.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.553-565
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• 2001

One-bottle adhesive system was recently developed in order to simplify the clinical skills and save chair time after continuous improvements on dentin bonding agents. To test the shear bond strength of a new "one-bottle adhesive" system to bovine dentin various commercially available one-bottle adhesives(Prime & Bond $2.1^{(R)}$, One Coat $Bond^{(R)}$, Syntac $Sprint^{(R)}$, Single $Bond^{(R)}$) were included for comparison. And we observe the interfacial morphology by scanning electron microscope. The results were as follows; 1. Group II (One Coat $Bond^{(R)}$) showed higher shear bond strength than group I (Prime & Bond $2.1^{(R)}$), group III(Syntac $Sprint^{(R)}$), and group IV(Single $Bond^{(R)}$), but no statistically significant difference was founded between groups(p>.05). 2. Relating reverse-cone shape resin tags were observed in samples of all groups under SEM. We could observed hybrid layer, resin tag and many lateral branches in every group. But, we observed in group III rare lateral branched than other three groups, and discontinuous hybrid layer.

• Journal of Communications and Networks
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• v.8 no.2
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• pp.241-252
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• 2006

Traditional service-level agreements (SLAs), defined by average delay or packet loss, often camouflage the instantaneous performance perceived by end-users. We define a set of metrics for service availability to quantify the performance of Internet protocol (IP) backbone networks and capture the impact of routing dynamics on packet forwarding. Given a network topology and its link weights, we propose a novel technique to compute the associated service availability by taking into account transient routing dynamics and operational conditions, such as border gateway protocol (BGP) table size and traffic distributions. Even though there are numerous models for characterizing topologies, none of them provide insights on the expected performance perceived by end customers. Our simulations show that the amount of service disruption experienced by similar networks (i.e., with similar intrinsic properties such as average out-degree or network diameter) could be significantly different, making it imperative to use new metrics for characterizing networks. In the second part of the paper, we derive goodness factors based on service availability viewed from three perspectives: Ingress node (from one node to many destinations), link (traffic traversing a link), and network-wide (across all source-destination pairs). We show how goodness factors can be used in various applications and describe our numerical results.

• The Journal of Korean Academy of Prosthodontics
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• v.23 no.1
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• pp.125-136
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• 1985

Occlusal splints have been widely used in dentistry for treatment and diagnosis of signs and symptoms related to dental occlusion. The autor studyed the effect of occlusal splint on masticatory movement of young adult men (mean age 23.8 yrs.). Who had worn. occlusal splint for 1 week. The result were as follows: 1. Lateral movement of the mandible during mastication could be increased after wearing occlusal splint for 1 week. 2. Vertical movement of the mandible during mastication was increased after wearing occlusal splint for 1 week. 3. Maximum opening velocity of the mandible during mastication was increased after wearing occlusal splint for 1 week. 4. Mandibular movement during mastication was more affected by chewing of hard foods than of soft foods following occlusal changes. 5. Steepness of the anterior guidance affected several aspects of masticatory movement. 6. Masticatory movement of the mandible became more regular after wearing occlusal splint for 1 week.