• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.337-348
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• 2017

The tension of warp from trawler and sea-floor contact can generate tilt and wake turbulence around otter boards. Preliminary measurements of otter board tilt and 3-D flow velocity during bottom trawl operations were taken using a vector instrument to investigate the effects of wake turbulence at the trailing edge of the otter board. Tilt data (i.e., yaw, pitch, and roll) at 1 Hz and flow data (velocities in the towing, lateral, and vertical directions) at 16 Hz were analyzed to determine their periods and amplitudes using global wavelet and peak event analyses. The mean period (${\pm}standard$ deviation) of the tilt from the peak event analysis ($5{\pm}2s$) was longer or double than that of flow velocity ($3{\pm}2s$). The two periods also had a significant linear relationship. The turbulence rate of flow was 30-50% at the trailing edge and was closely related to roll deviation. The frequency of phase difference ratios (i.e., peak time differences between tilts and flow periods) was significantly different from random occurrence in two trials, possibly due to side tidal effects. However, in the other trials, flow peaks were random, as shown by the even peak times between tilts and flows. Future studies should focus on reducing tilt variation, wake turbulence, and bottom contact to stabilize otter board motion.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.1
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• pp.223-235
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• 2014

The purpose of this study is to investigate school administrators' perceptions of school evaluation, examining the current situation in the hope of finding solutions to the problems caused by current evaluation. The subjects of this research were consisted of 230 middle and high school administrators in Busan. The instrument used for the study were the questionnaire included 27 questions concerning the current situation, the problems and improvements of school evaluation. The results of this study were as followed: (1) school administrators generally have a positive attitude toward school evaluations. But, they thought need to enhance their leadership qualities so that teachers can feel more positive about participating in school evaluation. (2) school administrators have to show more of an interest in the planning, performance and the use of the results of evaluation. (3) to enhance the quality of teaching practices in school they have to improve their methods for providing feedback of the results of evaluations. (4) the biggest problem related to school evaluation is the lack of quality and professional knowledge of the evaluation teams. And each school develops a unique curriculum and focuses on the improvement of instruction methods.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.1
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• pp.260-273
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• 2013

This study aims to reflect experts' opinions in analyzing a design thinking as foundation of multidisciplinary education. For this purpose, a delphi survey was conducted with 20 experts in three sessions from May 1 to June 25, 2012. To analyze the collected data, descriptive statistics, including frequency, percentage, the mean, and standard deviation were implemented, and internal reliability test on the survey instrument was carried out for statistical processing. The main results are as follows : First, the delphi analysis on intuitive thinking of design thinking suggested 7 items(to pursue the possibility of outside, to pursue the possibility of applying new forms of technology, content planning, facing a complex real-world phenomena etc.). Second, the delphi analysis on logical thinking of design thinking suggested 7 items(executed repeatedly, reasoning and verification, artificial intelligence, a decision support system etc.) Third, the delphi analysis on subjective thinking of design thinking suggested 9 items(user experience measuring, user satisfaction ratings, user requirements analysis, user interface design, behavioral responses of the human etc.). Fourth, the delphi analysis on objective information of design thinking suggested 8 items(information management system, simulation, production process, information exchange and sharing etc.). According to the results of the delphi analysis, design thinking can be seen as the foundation of multidisciplinary education. Suggestions were made for discussion about the main results and further researches.

• Journal of Fisheries and Marine Sciences Education
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• v.19 no.2
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• pp.288-300
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• 2007

The study was designed to lay the ground for effective guidance toward adaptive coping behavior by finding out differences in ego-resiliency in terms of personality types in the Murphy-Meisgeier Type Indicator for Children(MMTIC). For the study, personality types and ego-resiliency of 180 fifth- and sixth-grade students from 3 elementary schools located in Busan were measured. The instrument for personality types was MMTIC, which was developed by Meisgeier and Murphy in the US in 1990 and standardized in Korea in 1993 by Jungtaek Kim and Hyesook Shim. In order to measure Ego-Resiliency, Block & Kremen(1996)'s Ego-Resiliency scale translated and remodified by Sungkyung Yoo(2004) was used. The collected data were analyzed using ANOVA. The study found the followings: Firstly, according to the children's preference for personality types, participants' ego-resiliency scores appeared significantly higher in 'Extraversion', 'iNtuition', and 'Feeling' than in 'Introversion', 'Sensing', and 'Thinking' respectively. There was no significant difference in the score between in 'Judging' and 'Perceiving'. Secondly, according to function types of MMTIC, the participants' ego-resiliency score in 'iNtuition-Feeling' type showed the highest among scores in the other three types. The score in 'iNtuition-Feeling' type was significantly higher than 'Sensing-Thinking', 'Sensing-Feeling', and 'iNtuition-Thinking' type respectively.

• Journal of Fisheries and Marine Sciences Education
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• v.19 no.1
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• pp.91-100
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• 2007

The purpose of this study was to compare personality existed in the populations of the mentally retarded with and without Down syndrome. For this purpose, two research questions were proposed. (a) Is there any difference of personality existed between two groups? (b) Is there any difference of sub-personality existed between two groups by disability degree? Participants in this are 159 people with mental retardation(the mentally retarded with Down syndrom: 82, the mentally retarded without Down syndrom : 77) in P and S cities. First of all, the reliability in measurement instrument was verified through a pre-study. For the first research question, t-test was used. And two way ANOVA was used to investigate the second research question. The results of this study were as follows:First, according to the result of t-test, there were significant differences of personality scores between two groups. And there were significant differences between the mentally retarded with and without Down syndrome regard to expectation of success, outerdirectedness, positive or negative responding tendency, curiosity among sub-personality factors. Second, the result of the two way ANOVA analysis, no meaningful statistically difference in personality by degree of the impairment. But It showed difference regard to effectancy motivation, expectation of success, curiosity among sub-personality factors between the mentally retarded with and without Down syndrome by impairment degree.

• Journal of Fisheries and Marine Sciences Education
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• v.23 no.4
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• pp.648-661
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• 2011

The purpose of this study was to examine the school parent and student's perception of Practical Arts and Technology Home Economics and to suggest plan to school parent of multicultural and learning disability families. The subjects of this study were elementary and secondary teachers who teaching Practical Arts or Technology Home Economics. The instrument of this study was questionnaire including five sections: influence on students by Practical Arts and Technology Home Economics, interest in Practical Arts and Technology Home Economics to school parents, school support with learning ability improvement, school parents support with home in Practical Arts and Technology Home Economics, data form of school parents support with home in Practical Arts and Technology Home Economics. The findings of this study were as follows; Sociality development of students is influential by Practical Arts and Technology Home Economics. School parents and students believe important subjects in Practical Arts and Technology Home Economics. Teachers ask for support with learning ability improvement for practical training space and programs in Practical Arts and Technology Home Economics. School parents ask for support with learning ability improvement of programs of teaching learning method for home education on Practical Arts and Technology Home Economics.

• Journal of Sensor Science and Technology
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• v.31 no.1
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• pp.64-68
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• 2022

Herein, we propose a LoRaWAN-based small draft system that can measure the ocean current flow (speed, direction, and distance) in real time at the request of the Coast Guard to develop a device that can promptly find survivors at sea. This system has been implemented and verified in the early stages of rescue after maritime vessel accidents, which are frequent. GPS signals often transmit considerable errors, so correction algorithms using the improved triangulation method algorithm are required to accurately indicate the direction of currents in real time. This paper is structured in the following manner. The introduction section elucidates rescue activities in the case of a maritime accident. Chapter 2 explains the characteristics and main parameters of the GPS surveying technique and LoRaWAN communication, which are related studies. It explains and expands on the critical distance error correction algorithm for GPS signals and its improvement. Chapter 3 discusses the design and analysis of small draft buoys. Chapter 4 presents the testing and validation of the implemented system in both onshore and offshore environments. Finally, Section 5 concludes the study with the expected impact and effects in the future.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.898-904
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• 2021

This experimental study aims to investigate the use of a wet electrostatic precipitator as a post-treatment device to satisfy the strict emission regulations for sulfur oxides and particulate matter (PM). The inlet/outlet of a wet electrostatic precipitator was installed in a funnel using a marine four-stroke diesel engine (STX-MAN B&W) consuming marine heavy fuel oil (HFO) with a sulfur content of about 2.1%. Measurements were then obtained at the outlet of the wet electrostatic precipitator; an optical measuring instrument (OPA-102), and the weight concentration measurement method (Method 5 Isokinetic Train) were used for the PM measurements and the Fourier transform infrared (FT-IR; DX-4000) approach was used for the sulfur oxide measurements. The experimenst were conducted by varying the engine load from 50%, to 75% and 100%; it was noted that the PM reduction efficiency was a high at about 94 to 98% under all load conditions. Additionally, during the process of lowering the exhaust gas temperature in the quenching zone of the wet electrostatic precipitator, the sulfur dioxide (SO₂) values reduced because of the cleaning water, and the reduction rate was confirmed to be 55% to 81% depending on the engine load.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.55-60
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• 2004

In this study, the configuration and tension of a towing cable for side-scan sonar are predicted in an ambient flow and at an unsteady towing condition. The governing equation of three-dimensional dynamic analysis for a flexible cable is solved using a finite difference method. We successfully predict the configuration and tension of a side-scan sonar and designed the towing system. It is found in static analyses that the side-scan sonar must be towed to keep a its stable depth at a reasonable speed. The study also reveals in the transient analyses that the dominant component affecting the top tension is the tangential drag force for the larger towing speed than the critical speed, and the self weight of a towed instrument for the smaller towing speed than. It should be maneuvered for a towing vessel with good consideration for the impact effect in a cable due to tension peak when a towing speed is suddenly increase. The developed program can be applicable for three-dimensional dynamic analysis of a towing system for various marine survey instruments.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.32-44
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• 2015

In general, a series of ship steering motion is represented by the combination of translational motion and rotational motion of the ship. Especially, special-functioned ships such as large-scale cruises, ships for installing underwater optical cable, and diver ships must be able to reveal only a translational motion without the change of orientation. In this paper, a method to comprise an integrated control system based on the joystick as a command instrument for translational motion control is suggested. In order to realize the translational motion control system, several algorithms are suggested including the velocity command generation, the selection of motional variables, and the generation and tracking of reference inputs for the selected motional variables. A simulation bench is composed to execute simulations for several translational motion commands. At last, the effectiveness of the proposed method is verified by analyzing the simulation results.