• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.4
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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.

• Journal of Korean Society of Forest Science
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• v.97 no.5
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• pp.540-546
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• 2008

Enrichment planting has been used as one of the promising restoration techniques to accelerate the natural restoration process of secondary forests or logged-over forests in Myanmar, The objectives of this study were to examine the growth performances of two commercial species such as Teak (Tectona grandis Linn f.) and Padauk (Pterocarpus macrocarpus Kurz) in response to different canopy opening treatments and to examine the suitability of these species in enrichment planting activities for the restoration of degraded tropical forests in Myanmar. In this study, split plot design was applied, and three levels of canopy openings were experimented. The survival rate and height growth of two species were measured four times with 6 month interval. The root collar diameter (RCD) was also measured in the last assessment. Although the survival rate of seedlings was not significantly different among the three treatments (p>0.05) as well as between two species (p>0.05) for all consecutive measurements, height (p<0.05) and RCD were significantly different (p<0.001) among the treatments, T. grandis seedlings thrived best under complete canopy opening (i.e., 5 m width canopy opening with strip-clear cutting) while P. macrocarpus seedlings under partial canopy opening (without felling of marketable tree species). Because this study is concerned with only for young stage of seedlings, continuous assessment and follow-up tending activities are needed to verify the species suitability and optimum width of canopy opening for enrichment planting activities in restoration of degraded forests of Myanmar.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.593-599
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• 2001

Recently, tempormandibular disorder(TMD) shows an tendency to increase every year. TMD is a collective term embracing a number of clinical problems that involve the masticatory musculature, temporomandibular joint(TMJ) and associated structures, or both. TMD, viewed in distribution of age, often occurred from late teens to late twenties. But recently, the age of occurrence tends to be lower. Accordingly, early diagnosis of tempormandibular disorder is very important. In this study, we measured the maximum mouth opening which is simple and easy to carry out as a way of TMD diagnosis. In this study, the maximum mouth opening was examined for 1,775 children from 4 to 12 years of age. We compared the relationship between the maximum mouth opening with the age, height, and weight. The results obtained were summarized as follows; 1. The mean maximum mouth openings of 4, 8, and 12 year of age were respectively 40.16mm, 47.32mm, 50.54mm for male, 39.79mm, 44.85mm, 48.09mm for female. 2. The maximum mouth opening increased with age, and the values were greater in male than in female. 3. The maximum mouth opening increased with height, and the values were eater in male than in female except between 105cm and 115cm 4. The maximum mouth opening increased with weight, and the values were eater in male than in female. 5. The correlation between the maximum mouth opening with the age, height, and weight was all significant, and height showed the highest correlation.

• The Journal of Pediatrics of Korean Medicine
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• v.17 no.2
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• pp.1-13
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• 2003

Objectives: The purpose of this study was to suggest a scientific method for measurement of children's growth development. Ultrasonic image of calcaneus bone has some advantages that it is harmless to human body and apply a new imaging analysis algorithm. it can be used for the diagnosis of growth analyzed the opening degree of growth plate and bone density. Methods: This clinical study have been carried out with the 57 case(male 24, female 33) of the children aged 5 to 14 years old who visited in Department of Pediatrics, Dongguk university Bundang Oriental Hospital. Bone maturity is measured by the opening degree of growth plate and bone density in ultrasonic image of calcaneus bone This study were designed to investigate the relationship of the development of children and the calcaneus bone maturity. Result: The opening degree of growth plate was no change in aged 5-10 years for male and 5-9 years for female but decreased significantly from aged 11 years for male and 10 years for female. the bone density was no change in aged 5-12 years for male and 5-11 years for female but increased significantly from aged 13 years for male and 12 years for female. it was confirmed that bone maturity in female is more rapid than in male. The opening degree of growth plate of claclneus bone was correlated with age, height, weight. The bone density was correlated with age, height, weight, BMI in this suudy(P<0.001) Conclusion: The opening degree of growth plate and bone density of calcaneus bone are sufficient diagnostic worth as an index to predict adolescent growth.

• Transactions of Materials Processing
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• v.16 no.6
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• pp.457-462
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• 2007

The drawbeads, which are used for controlling the flow of the sheet into die cavity by imposing the tension and for preventing the forming defects like wrinkling, springback, etc. during the sheet forming process, affect the formability strongly because of the differences in the restraint and opening forces according to the drawbead shapes and dimensions. In this study, the experimental device enabling to measure the drawbead restraining and opening forces is manufactured and the drawing forces of circular, square, and step drawbeads are measured. The drawbead restraining and opening forces of a circular drawbead are increased as its drawbead height is increased. Similarly, those of a square drawbead are increased as its height is increased and shoulder radii decreased. The drawbead forces obtained from the experiment were compared with those calculated in the numerical simulation of stamping process of automotive fender. Good agreement was found so that the experimental measurements can be used in the simulation of auto-body stamping process.

• Journal of the Korean Solar Energy Society
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• v.35 no.1
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• pp.69-80
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• 2015

A series of numerical analyses was conducted to predict the thermal performance of a solar air heater depending on the hole configuration and geometry in the absorber plate. The planar dimensions of the prototype were 1 m (W) by 1.6 m (H), and the maximum air flow considered was $187m^3/h$. It was considered that protruding holes with a triangular opening in the absorber plate would invoke turbulence in the air flow to enhance the convection heat transfer. Six different hole configurations were investigated and compared with each other, while the hole opening height was considered as a design variable. Three-dimensional transient analyses were performed with a commercial software package on the airflow and heat transfer in the model. The numerical results were analyzed and compared from the view point of the outlet air temperature and its time response to derive the optimal hole pattern and hole opening height.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.2
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• pp.66-73
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• 2021

In the existing study of steel beams with openings, openings are located at a location where the distance to the support point is equal to or greater than the section height. Considering the facilities using the openings in the steel beam, the distance from the opening to the support point may be closer than the height of the beam section. Therefore, research on this is needed. This study is an experimental study to understand the structural performance of beams with openings close to the ends subjected to Cyclic Loading. In addition, in this study, we want to understand the structural performance through experiments on beams with openings reinforced with vertical or horizontal steel plates.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.138-145
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• 2020

This study was conducted to identify the structural performance of the opening in a location close to the support point in the perforated beam system of steel beams. In addition, structural performance was determined through experiments on reinforced openings using vertical and horizontal steel plates. In the steel simple beam, it was found that the opening was in a position closer to the support point, half the height of the steel beam (D/2), which was more appropriate than the height of the steel beam (D). In addition, the reinforcement effect of horizontal steel plate was greater than that of vertical steel plate reinforcement. Structural performance was improved when there was no gap between openings and steel plates.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.1
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• pp.1-11
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• 2018

This study was conducted in order to improve fishing gear for existent net of the anchovy boat seine. Field experiments were performed to observe geometry of nets by catcher boats. When the distances between the two ships were 100, 300, and 500 m, and the speeds of towing nets were 0.6, 0.9, and 1.2 k't, respectively. The vertical opening and actual opening of each part of the existent net was as follows: the middle part of the wing net, 12.9-26.6 m, 19-39%; the entrance of the inside wing net, 23.3-35.3 m, 40-60%; the square and bosom, 18.4-24.2 m, 37-49%; the entrance of the bag net, 19.0-23.3 m, 79-96%; the flapper, 13.2-15.3 m, 142-161%; and the end of the bag net, 13.2-15.7 m, 51-61%. The actual net opening of each part of the existent nets used in this study was lower than that of the design net height, due to the low net height of the wing net and the inside wing net, it limited a range of the net height of the square and bosom. The opening of the entrance of the bag net caused the net pocket shape and inflated some parts of the nets. The tension of towing nets was measured between 4.4 and 11.0 tons, and it is necessary to reduce the structure and improve the structure of the bag net.

• Journal of the Korean Society of Safety
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• v.9 no.3
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• pp.60-66
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• 1994

The purpose of this study is to compare the combustability of the formed high density polyethylene (HDPE) with the low density polyethlyene(LDPE). That is, the easiness of ignition is examined by using the methods with Oxygen Index(OI) Tester and ventilation parameter, and the combustion velocity of these polyethylenes is measured by changing the size and shape of opening area. As the result of it, the oxygen index of HDPE, in a ignition, is required more than LDPE. Then, the concentration distribution of CO by combustion is increased when the opening area is small, but, in the same opening area, LDPE tends to increase more than HDPE. In addition, as the ratio of height to width of opening area is increased, combustion velocity becomes faster relatively. In consequence, when it is generally considered, the combustability of LDPE is better than HDPE.