• PNF and Movement
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• v.15 no.3
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• pp.281-290
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• 2017

Purpose: The purpose of this study was to examine the effect of an 8-week competitive exercise program on physical fitness, psychological variables, and video-game playtime in game-addicted adolescents. Methods: All subjects were screened by a game behavior diagnosis scale questionnaire, and a total of 7 game-addicted, male adolescents ($16{\pm}2$ yrs of age) participated in the study. All subjects were informed of the study's purpose, procedures, and risks, and a consent form was obtained from each subject. The 8-week soccer and basketball exercise program included twice-weekly sessions of 120 minutes per session. All data were presented as $mean{\pm}SE$, and the variables were analyzed with a paired t-test. Results: Following the 8-week intervention, cardiovascular endurance and grip strength were significantly increased (approximately 17 and 7%, respectively [p<0.05]). Although there was no statistical significance on flexibility, vertical jump, and zigzag-run, all variables showed an increasing tendency. Anxiety levels changed from a mild anxiety state to a normal state, and depression levels also altered from moderate to a normal state. The video-game playtime was reduced about 20% during weekends and vacation periods. Conclusion: Given these combined results, 8 weeks of regular participation in competitive exercise (soccer/basketball) may contribute to positive effects on physical fitness, psychological variables, and video-game playtime in computer-game addicted adolescents.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.6 s.144
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• pp.551-558
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• 2005

In this paper, horizontal manoeuvrability of an underwater vehicle near free surface was investigated. Planar Motion Mechanism(PMM) tests were performed at the shallow depth within 4.5 times of vehicle's diameter. Hydrodynamic coefficients related to the horizontal movement were estimated from the measured data using Least SQuare(LS) method and analyzed at each submerged depth. Furthermore, horizontal dynamic stability, trajectory of turning and zigzag test were investigated for the various depths. As underwater vehicle is positioned nearer to the free surface, forces increase and moment decreases. Tested model was found to be stable only at the depth 0.5 times of vehicle's diameter.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2140-2142
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• 2005

This paper presents the experimental results on the preliminary breakdown characteristics under a highly non-uniform electric field in $SF_6/CO_2$ gas mixtures. The impulse preliminary breakdown developments are investigated by the measurements of corona current and light emission images. As a result, the preliminary breakdown development mechanisms for both positive and negative polarities are same. The first streamer corona is initiated at the tip of needle electrode, and the leaders develop with a stepwise propagation and bridge the test gap. The pause time of leader pulses in the positive polarity is significantly shorter than that in the negative polarity. Also, the time interval between the first streamer corona onset and breakdown in the negative polarity was much longer than that in the positive polarity The discharge channel paths in the positive polarity were zigzag. On the other hands, the leader channel in the negative polarity was thicker than that in the positive polarity.

• Journal of the Korean Society of Clothing and Textiles
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• v.42 no.3
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• pp.474-485
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• 2018

Smart sensors and connected devices have changed the concept of garments along with IT technology convergent garments that transform the performance of basic functions. Various types of products have been researched and developed due to the increased interest in smart clothing; in addition, studies based on physical and mechanical properties have also been actively studied to improve accuracy and reliability. This study represents a basic study for the development of smart textiles based on motion recognition for the surfing practice of beginners interested in IT convergence type. A physical durability evaluation of conductive yarn according to sewing method was later carried out. This study is a conditional specimen sewn with cotton lower thread and 100mm pattern length based on the results of previous studies. The durability of the conductive yarn according to the sewing method was evaluated according to the sewing method. Durability was evaluated by two kinds of repeated strain and abrasion tests. The specimen with applied cotton in a lower thread zigzag pattern 2mm stitch size 100mm stitch length was shown to have the most suitable durability for smart textile.

• Transactions of Materials Processing
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• v.30 no.6
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• pp.284-290
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• 2021

Manufacturing using a 3D printer has recently increased in many fields and the material extrusion method, which is a lamination method, is commonly used. Since it uses a plastic material, the strength of the output of 3D printing is lower than that of steel material. For this reason, research on improving the mechanical properties of the output of 3D printing is continuously being conducted. In this study, tensile strength was compared with changes in the material type (PLA+, ABS) and density (60, 80, and 100%), layer height (0.1, 0.2, and 0.3 mm), layer direction (transverse and lengthwise), and fill pattern (zigzag, honeycomb, and concentric) among 3D printing output conditions. Tensile tests according to 3D printing output conditions were performed using a Universal Testing Machine. The results showed that tensile strength ranged from 21.10 MPa to 43.65 MPa according to the 3D printing output conditions.

• The Korean Journal of Mycology
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• v.29 no.1
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• pp.34-40
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• 2001

RAPD test and the observation of morphological, cultural characteristics of fourteen selected entomogenous fungi were conducted to investigate the analysis of their internal relationships. Paecilomyces tenuipes showed snow flower form attached to numerous white conidiophores, produced globular and semi-egg types on the club types of phialides. Cordyceps militaris formed globosely conidiophores, dark yellow fruiting body on pupa. The phialide as on Acremonium-type in global conidiophores. Beauveria bassiana covered with conidia was not formed fruiting body and adhered conidia on conidiophore of zigzag type. The PDA and SDAY medium were confirmed as an optimum growth of them. P. tenuipes showed to velvet and plane types in several media whereas C. militaris was belong to centrally raised and floccose in the morphological type. In contrast, B. bassiana covered with conidia on velvet shape. The size of amplified products were analyzed by RAPD using URP primer and were from 100 bp to 2.0 kb with $10{\sim}14$ geuomic DNA. Total similarities of two groups were by dendrogram of UPGMA analysis. The homology of P. tenuipes groups was 94.8 to 100%. It also showed 70.1 to 96.6% in C. militaris group and B. bassiana was higher similarity than any other. The internal change of C. militaris, produced telemorph fruiting body, was higher seperated in species than P. tenuipes and B. bassiana in the RAPD.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.4
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• pp.383-389
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• 2011

At the design stage, it is very important to know the ship maneuvering characteristics from the view point of ship performance and for the safety of navigation. IMO only gives some criteria for ships in full load even keel condition. However, the ship generally is operated not only in full load condition but also in half load condition or ballast condition. Therefore we must estimate the ship maneuvering in different loading condition to ensure that the ship will satisfy with IMO rules and navigate safely in every condition. In this paper, we have investigated the maneuvering characteristics of a ship by simulation and experiments with real ship. By comparing with the results of simulation, the real ship tests conform with simulation test and previous researches. Therefore, the method base on real data is well done to estimate the ship maneuvering in different loading conditions. The change of ship's manoeuverability accoriding to ship's operation conditions was estimated.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.4
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• pp.435-442
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• 2011

In an attempt to respond to the increase in international oil prices and reduce operating expenses, ship remodeling was carried out on a 740ton class tuna purse seiner. To strengthen the competitiveness of the fisheries industry by improving vessel performance, a bulbous bow was newly equipped. The slipway and rudder area were also lengthened and enlarged with the propeller and main engine remained unchanged. To reduce the hull resistance, a circle type bulbous bow was attached on the hull behind bow thruster and thus the cost for exchanging electrical equipment for bow thruster was reduced. The new rudder area was expanded 15% more than the old one within the extent that the existing mechanical control part and rudder stock were not changed. To prevent fishing net damage and stabilize wake field, slipway was lengthened to the optimal position. All of the new design of remodeling parts went through the model tests in towing tank and CWC. Besides resistance test, all of necessary model test results were delivered for hydrodynamic character for the modified ship. The maneuvering simulation to verify that the remodeled ship satisfies the IMO rules was performed in both zigzag and turning tests. The estimated resistance with new bulbous bow and lengthened stern was reduced by 4.8% in the 2-dimensional analysis and 17.4% in the 3-dimensional analysis in comparison of conventional ship. The average reduction of resistance was estimated about 10%. Maneuvering character of modified hull form was found to satisfy all regulations under IMO. The remodeling of tuna purse seiner can not only improve fishing performance but also contribute to reduction of operating cost by saving energy for the fisheries industry.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.4 s.38
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• pp.11-18
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• 2006

In this paper, airborne LiDAR data were evaluated in horizontal and vertical accuracy. By using zigzag scanning type of LiDAR, GCPs are not tested directly. So points around GCPs were used in this evaluation. Building corner points were made from LiDAR's building planar and compared with ground surveyed GCPs, in horizontal accuracy test. Its accuracy shows 19cm average and 21cm RMSE and 15 points were within 20cm among 16 points. In vertical accuracy test, 41 GCPs were used and it shows 11cm average and 14cm RMSE and 75% of GCPs were within 15cm. This could be a criterion in topographic map modification and basic geographic DB and 3D data construction using airborne LiDAR data.

• Journal of the Korean Society of Clothing and Textiles
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• v.35 no.3
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• pp.292-303
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• 2011

This research suggested a draft proposal for a smart jacket design, which has applied wearable technologies to provide convenience in daily life. The smart jacket combined with a vest was the casual item for autumn and winter. The heating device was composed of the heating element, battery, controller, electric wire, connector, switch, and charger. A stable electronic conductor fiber of good heating effect with a flexible zigzag form has been selected for the heating element. The lighting device has been made in a way that attaches the LED and its power controller in the same mechanical device. As the result of the wearing test, the heating effect turned out to be effective in the order of: back, both the back and abdomen and only the abdomen. When wearing a smart jacket, the back and abdomen have been selected as favorable body parts for heating. Pockets and hems are selected as the adequate place to attach the LED lighting, and the brightness of LED lighting has turned out to be suitable and useful. Based on the test results, the first draft proposal has attached the heating element only in the back and its controller located in the inside pocket of the vest. In addition, the LED has been attached to the front pocket of the jacket. As to the second draft proposal, heating elements have been placed in the back and the abdomen. Each controller for the heating elements has been placed in the front and inside pocket of vest, and the LED lighting has been attached to the hem of the jacket. The smart jacket combined with a wearable device was assessed by functioning categories. The user showed a high satisfaction in the heating and illuminating function of a smart jacket.