• 수산해양기술연구
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• 제57권4호
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• pp.283-291
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• 2021

The Korean stow net is a fishing method that utilizes the changing direction of the net entrance with the tidal current. This study attempted to obtain basic data from the recent offshore stow net fisheries to improve the gear by analyzing the dynamic behavior of the nets affected by current speed and direction using computer simulations. A numerical calculation was performed at a current speed of 0.5 knot between 2.5 knot at each 0.5 knot. The time taken for the gear opening was the longest from 0.5 knot at 1,500 seconds and the shortest from 2.5 knot at 450 seconds in the simulations. In all cases, the net width and tension at net deployment gradually decreased as the current speed decreased. However, the net height tended to increase inversely proportional to the current speed. During the net rotation, the net height was maintained at all cases. The net width and tension fluctuated, but the regularity was very low. In this study, the calculated simulation data showed that the opening efficiency decreased proportional to the current speed. The opening efficiency is related to the catching efficiency; therefore, it is necessary to improve the gear to enhance its opening efficiency.

• 대한족부족관절학회지
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• 제19권3호
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• pp.102-106
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• 2015

Purpose: We wanted to compare the results between cadaveric and radiological measurements of calcaneus. Materials and Methods: Sixty three calcaneus of 33 cadavers donated between December 2012 and December 2014 were actually measured. Computed tomography (CT) images of 244 calcaneus in 122 patients of the same age group with cadavers were radiologically measured. Maximum length, maximum width, maximum height, $B{\ddot{o}}hler$ angle, Gissane angle, Fowler-Phillip angle, and tala-articular angle were measured. Results: In cadaveric measurement, the mean maximal height, length, and width were $41.8{\pm}3.3mm$, $73.3{\pm}3.4mm$, and $40.7{\pm}2.2mm$, respectively. In radiological measurement, the mean maximal height, length, and width were $38.5{\pm}4.3mm$, $74.0{\pm}5.7mm$, and $44.7{\pm}1.4mm$, respectively. In cadaveric measurement, the mean $B\ddot{o}hler$ angle, Gissane angle, Fowler-Phillip angle, and tala-articular angle were $32.1^{\circ}{\pm}6.2^{\circ}$, $110.8^{\circ}{\pm}8.1^{\circ}$, $55.8^{\circ}{\pm}6.8^{\circ}$, and $59.7^{\circ}{\pm}4.6^{\circ}$, respectively. In radiological measurement the mean $B{\ddot{o}}hler$ angle, Gissane angle, Fowler-Phillip angle, and tala-articular angle were $32.6^{\circ}{\pm}3.8^{\circ}$, $113.7^{\circ}{\pm}5.7^{\circ}$, $62.2^{\circ}{\pm}3.9^{\circ}$, and $61.6^{\circ}{\pm}6.3^{\circ}$, respectively. The mean maximal height was significantly higher in the cadaveric measurement group (p<0.001) and the mean maximal length and width were significantly higher in the radiologic measurement group (p<0.001, p<0.001). The mean Gissane angle, Fowler-Philip angle, and $B{\ddot{o}}hler$ angle were significantly higher in the CT group (p=0.001, p<0.001, p=0.016, respectively). There was no significant difference in the mean tala-articular angle (p=0.352). Conclusion: Significant differences in length parameters were observed between the cadaveric measurement group and the radiologic measurement group. However, no significant differences in angular measurements were observed between the two groups. The authors carefully conclude that radiological measurement values may be different from actual values in the calcaneus.

• Journal of Periodontal and Implant Science
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• 제40권5호
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• pp.227-231
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• 2010

Purpose: The healing process following tooth extraction apparently results in a pronounced resorption of the alveolar ridge. As a result, the width of alveolar ridge is reduced and severe alveolar bone resorption occurs. The purpose of this experiment is to clinically and histologically evaluate the results of using horse-derived bone mineral for socket preservation. Methods: The study comprised 4 patients who were scheduled for extraction as a consequence of severe chronic periodontitis or apical lesion. The extraction was followed by socket preservation using horse-derived bone minerals. Clinical parameters included buccal-palatal width, mid-buccal crest height, and mid-palatal crest height. A histologic examination was conducted. Results: The surgical sites healed uneventfully. The mean ridge width was $7.75{\pm}2.75\;mm$ at baseline and $7.00{\pm}2.45\;mm$ at 6 months. The ridge width exhibited no significant difference between baseline and 6 months. The mean buccal crest height at baseline was $7.5{\pm}5.20\;mm$, and at 6 months, $3.50{\pm}0.58\;mm$. The mean palatal crest height at baseline was $7.75{\pm}3.10\;mm$, and at 6 months, $5.00{\pm}0.82\;mm$. There were no significant differences between baseline and 6 months regarding buccal and palatal crest heights. The amount of newly formed bone was $9.88{\pm}2.90%$, the amount of graft particles was $42.62{\pm}6.57%$, and the amount of soft tissue was $47.50{\pm}9.28%$. Conclusions: Socket preservation using horse-derived bone mineral can effectively maintain ridge dimensions following tooth extraction and can promote new bone formation through osteoconductive activities.

• 한국환경복원기술학회지
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• 제24권5호
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• pp.15-23
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• 2021

This study was carried out to suggest an appropriate plant combination by evaluating the growth of flowering ground-cover plants planted with Festuca glauca 'Eljiah Blue' on the roof-top environment. As for the plant materials, Allium senescens and Chrysanthemum coreanum which are shorter than Festuca glauca 'Eljiah Blue' and Sedum takesimense and Agastache rugosa which are taller than Festuca glauca 'Eljiah Blue' were selected. Festuca glauca 'Eljiah Blue' was planted on Conrol, and Festuca glauca 'Eljiah Blue' with Allium senescens (T1), Festuca glauca 'Eljiah Blue' with Sedum takesimense (T2), Festuca glauca 'Eljiah Blue' with Agastache rugosa(T3), and Festuca glauca 'Eljiah Blue' with Chrysanthemum coreanum (T4) were planted in each experimental plot. Plant height and covering rate were measured to evaluate the growth of Festuca glauca 'Eljiah Blue'. Also, relative growth rate (RGR) of plant height, RGR of plant width, and mortality rate of the flowering ground-cover plants were estimated. Plant height and cover rate of Festuca glauca 'Eljiah Blue' was greatest in T3. RGR of plant height was greater in the order of Agastache rugosa, Allium senescens, Chrysanthemum coreanum, and Sedum takesimense. In particular, RGR of plant width was also greatest for Agastache rugosa. Mortality rates of Agastache rugosa and Allium senescens were lowest at 11%. Therefore, based on good growth of Festuca glauca 'Eljiah Blue' planted with Agastache rugosa, these results were suggested as a desirable combination of plant species for rooftop gardening.

• 한국운동역학회지
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• 제20권3호
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• pp.319-325
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• 2010

The purpose of this research was to investigate the differences in the ski carving turn motion according to level of expertise. The posture and movement of 6 skiers nearby the fall-line was evaluated with a biomechanical approach focusing the rotational mechanics. The slope was at an angle of $9^{\circ}$ and the following variables were measured and calculated: tangential velocity, change of COM height after passing fall-line, width between feet, angle between upper body and thigh, trunk angle, average radius of curvature and average centripetal force. The expert skiers minimized their center of mass height movement and maintained the width of between their feet after the passing the fall-line in comparison with the beginners and intermediate skiers. The experts restrained themselves from pushing their upper body downward after the turn to maximize the centripetal force. The experts in comparison with the beginners and intermediate skiers during the turn didn't have to reduce their radius of curvature to maintain a high centripetal force. It was concluded, that the most important factor affecting the centripetal force, was for the beginners and intermediate skiers, to minimize their movement while using the appropriate amount of edging.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.241-247
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• 2001

A comparison of fully developed heat transfer and friction factor characteristics has been made in rectangular ducts with ones roughened by five different shapes. The effects of rib shape geometries and Reynolds number are examined. The rib height-to-duct hydraulic diameter, pitch-to-height ratio, and aspect ratio of channel width to height are fixed at e/De=0.0476, P/e=8, and W/H=2.33, respectively. To understand the mechanisms of the heat transfer enhancements, the measurements of the friction factors are also conducted in the smooth and rough channels. The data indicates that the triangular type rib has a substantially higher heat transfer performance than any other ones in the range we studied.

• 동력기계공학회지
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• 제5권2호
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• pp.30-35
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• 2001

A comparison of fully developed heat transfer and friction factor characteristics has been made in rectangular ducts with one wall roughened by five different shapes. The effects of rib shape geometries and Reynolds number are examined. The rib height-to-duct hydraulic diameter, pitch-to-height ratio, and aspect ratio of channel width to height are fixed at $e/D_e=0.0476$, P/e=8, and W/H=2.33, respectively. To understand the mechanisms of the heat transfer enhancements, the measurements of the friction factors are also conducted in the smooth and rough channels. The data indicate that the triangular type rib has a substantially higher efficiency index than any other ones in the range we studied.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.453-458
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• 2009

This paper presents a numerical evaluation of the flow rate of air conditioner outdoor unit as function of shroud design parameters. To determine the optimal design parameters, we investigated the flow rate by changing bell mouth height, fan height, fan guide height, fan width. The evaluation of the relative priority of the design parameters was performed to choose three important parameters in order to use a response surface method. The flow rate of the optimum model, compared to that of the base model, was increased by about 6.25%.

• Journal of Mechanical Science and Technology
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• 제16권4호
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• pp.549-556
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• 2002

An investigation on the fully developed heat transfer and friction factor characteristics has been made in rectangular ducts with one-side roughened by five different shapes. The effects of rib shape geometries as well as Reynolds numbers are examined. The rib height-to-duct hydraulic diameter, pitch-to-height ratio, and aspect ratio of channel width to height are fixed at e/De=0.0476, P/e=8, and W/H=2.33, respectively. To understand the characteristics of heat transfer enhancements, the friction factors are also measured. The data indicates that the triangular type rib has a substantially higher heat transfer performance than any other ones.

• 설비공학논문집
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• 제13권5호
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• pp.341-347
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• 2001

A comparison of fully developed heat transfer and friction factor characteristics has been made in rectangular ducts with ones roughened by five different shapes. The effects of rib shape geometries and Reynolds number are examined. The rib height-to-duct hydraulic diameter, pitch-to height ratio, and aspect ratio of channel width to height are fixed at $e$/De=0.0476, P/$e$=8, and W/H=2.33, respectively. To understand the mechanisms of the heat transfer enhancements, the measurements of the friction factors are also conducted in the smooth and rough channels. The data indicates that the triangular type rib has a substantially higher heat transfer performance than any other ones in the range we studied.