• Journal of the Society of Naval Architects of Korea
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• v.29 no.4
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• pp.87-97
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• 1992

Of various design factors affecting icebreaking capability of an icebreaker, the stem angle(i.e., angle between bow stem and ice sheet) is the most important one under continuous icebreaking operation. This study focuses on the relationship between the bow stem angle of an icebreaker and its icebreaking capability. Considering relatively high loading-rate conditions with typical advancing speed of 3 to 4 knots, the material properties and deformation characteristics of sea ice are regarded as entirely elastic and brittle. In this paper the interaction process of icebreaker with level ice is simplified as a beam of finite length supported by Winkler-type elastic foundation simulating water buoyancy. The wedge type ice beam is loaded by the vertical impact forces due to the inclined bow stem of icebreaking vessels. The numerical model provides locations of maximum bending moment where extreme tensile stress arises and also possible fracture occurs. The model can predict a characteristic length of broken ice sheet upon the given environmental and design parameters.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.3
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• pp.187-195
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• 2018

Ship's bottom slamming has been studied by many researchers for a very long time. But still some ships suffer structure damages caused by the bottom slamming impacts. This paper presents a practical computation method of the design impact pressure due to ship's bow bottom slamming. Large heave and pitch motions of a rigid hull ship are simulated by the nonlinear strip method in time domain and the relative colliding velocity between the bow bottom and the water surface is calculated using the simulated ship motions. The bottom slamming impact pressure is calculated as a product of the relative colliding velocity squared and the bottom slamming pressure coefficient that is obtained by modification of the SNAME pressure coefficients based on Ochi's slamming experiments. Not only the bottom slamming pressures but also the required bottom plate thicknesses are calculated and compared with those of the classification society rules. The comparisons show good agreements and it is confirmed that the present method is practically very useful for the bottom structure design against ship's bow bottom slamming impacts.

• Journal of Navigation and Port Research
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• v.37 no.2
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• pp.143-148
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• 2013

The aim of this study is to investigate the characteristics on the profile of local ice load acting on side shell of port side in bow part due to broken ice during icebreaking of ships in ice covered waters. The first Korean icebreaking research vessel 'ARAON' had a sea ice field trial in the Arctic Sea during early August, 2010, and the signals due to local ice impact measured from several strain gauges installed at bow part were gathered. It is known that these data with structural response characteristics due to local ice impact have some different characteristics with a typical hydraulic impact pressure - time history. In this study, the time history on the measured signals was analyzed and the characteristic values were presented using non-dimensional parameters.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.965-971
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• 2017

The primary objective of this study was to assess the energy efficiency performance of an optimized hull form capable of saving energy based on existing vessels. The bow shape of existing vessels was investigated, giving consideration to design draft and speed. Resistance performances were also assessed for existing vessels according to operating conditions. Commercial CFD codes and model test materials were used to assess effective power. An optimized hull form with minimum resistance was selected given real operating conditions. The effective horsepower of existing and optimized vessels was estimated at three speeds. Resistance performance for an optimized vessel showed a 6 % improvement in effective horsepower at design speed (12 knots) compared to existing vessels. Quasi-propulsive efficiency employed experimental data, while energy efficiency performance was analyzed based on operating days, bunker fuel oil C cost, daily fuel oil consumption and specific fuel oil consumption. Energy efficiency performance for an optimized vessel showed a gain of 30 million won per year in reduced costs at design speed (12 knots) compared to existing vessels.

• Journal of the Korean Data and Information Science Society
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• v.23 no.6
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• pp.1055-1064
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• 2012

This research was to count and quantify relative importance through analytic hierarchy process on checkups items in order to solve the questions raised by uniformalized numbering in the established athletes self management test. This study has the following results. The relative importance in priority factors of the test is in following order of training management, mental care, body care and interpersonal management. It was also confirmed that relative importance varied according to every checkup item in the lower factors. Consequently, the new result from this study, as an initial research for the relative importance of athletes self management test, supplied the possibility in which the sports-field expert's opinion was reflected. It was expected that this study would be helpful for enhancing athletes' competence in the sports field.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.539-547
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• 2016

The study is conducted to investigate the prevalence of a yips phenomenon in high school baseball players and provide the basis of its origin and an effective treatment intervention. Therefore, we survey 320 high school baseball players registered at Korea Baseball Association, excluding poorly answered 30 questionnaires. Utilizing PASW 20.0, the analysis of yips experiences and a coping method is carried out with descriptive statistics and ratio analysis. The results from the process above are as follows. The ratio of high school baseball players who experience yips reaches 64%, which is significantly high; experiencing yips, they have both physical and psychological problems; although they would have psychological trainings, few of them work, which implies that the discussion on yips prevention and coping methods for high school baseball players is imperative.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.233-241
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• 2022

The purpose of this study is to verify the relationship between sports players' SNS interaction, relationship commitment, relationship satisfaction, and loyalty. To this end, a total of 000 copies of data were obtained by conducting a survey on the online community of sports stars who followed or subscribed to sports stars through the 2022 Beijing Winter Olympics, and the results were as follows. First, it was found that sports players' SNS interaction had a positive effect on relationship commitment. Second, it was found that sports players' SNS interaction had a positive effect on relationship satisfaction. Third, it was found that relationship commitment had a positive effect on relationship satisfaction. Fourth, it was found that relationship commitment had a positive effect on loyalty. Fifth, relationship satisfaction was found to have a positive effect on loyalty.

• 대한정형외과스포츠의학회:학술대회논문집
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• 2001.11a
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• pp.38-38
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• 2001

• Journal of Digital Convergence
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• v.10 no.11
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• pp.395-402
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• 2012

This study has been conducted to design and implement smart phone-based application which can keep records effectively to improve athletes' ability. To boost their performance, they need to receive training as realistic as possible. As a way to do that, training should be performed with some fitness equipments, sporting apparatus, facilities, and conditions. However, it is also possible to improve their ability by motivating athletes with checking and recording their performance. This study ascertains that using scoring records actually motivates athletes when comparing the result of youth basketball team using the records keeping system with that of not using it. Accordingly, smart phone-based records keeping application has been designed and developed. Also, through a survey targeting athletic coaches who have used the system, training efficiency has been measured and it turns out that it actually motivates athletes to improve their abilities.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.1
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• pp.15-20
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• 2017

The International Maritime Organization(IMO) has adopted and implemented compulsory regulation for reducing greenhouse gas emission that cause global warming. However, with global warming underway, the IMO plans to enforce voluntary carbon dioxide emissions reduction based on the Ship Energy Efficient Management Plan and the Energy Efficiency Operational Indicator(EEOI) in the near future. Large container ships sail at low speeds in order to save fuel and reduce carbon dioxide emissions. However, bulbous bows designed for high-speed ships decrease fuel efficiency by acting as resistance when reduced speeds are adopted by large container ships. In order to adopt low-speed operations and increase fuel savings, the bulbous bow of a large container ship was modified into the proper shape and size. Fuel consumption was compared for checking the result of EEOI before and after modifying the bulbous bow adopted on low speed operation of large high-speed ships. The results confirmed much larger carbon dioxide emissions reduction than expected. If EEOI would be implemented as compulsory regulation for reducing carbon dioxide emissions, bulbous bow modification can be considered as one of the fuel saving methods for the high-speed ships.