• Journal of Navigation and Port Research
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• v.37 no.3
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• pp.299-307
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• 2013

The purpose of this study were to analyze the effects of a marine leisure exhibition event(MLEE)'s service quality dissatisfaction levels on complaining behaviors and repurchase intentions and thus to provide fundamental marketing information for the event to be more successful. In order to accomplish such study purposes, this study employed a survey method with a total of 350 visitors to a MLEE hosted by G Province in 2012. The data collected were analyzed using multiple regression analysis and following findings were derived from current study. First, levels of service quality dissatisfaction were ranged from 3.29 point to 3.85 point at 7 point Likert scale. Second, both environment and exhibition facility had a positive effect on visitors' complaining behaviors, and both employee and environment factors had a positive effect on non complaining behavior. Third, only exhibition facility had a negative effect on repurchase behaviors including revisit intention and recommendation intention. Finally, complaining behavior had a negative effect on recommendation intention as well as revisit intention. Such findings provide important marketing information for induce more visitors to a MLEE, which are an index for the event's performance.

• The Journal of Engineering Geology
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• v.15 no.2 s.42
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• pp.155-168
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• 2005

The behavior of earth retention wall installed in a cut slope is different from the behavior of retention wall applied in an urban excavation. In order to establish the design method of anchored retention wall in the cut slope, the behavior of anchored retention wall needs to be investigated and checked in detail. In this study, the behavior of anchored retention wall was investigated by the instrumentation installed in the cut slope, where was stabilized by a row of piles in an apartment construction site. The horizontal displacement of anchored retention wall was larger than the displacement of slope soil behind the wall at the early stage of excavation. As the excavation depth became deeper, the horizontal displacement of slope soil was larger than the displacement of anchored retention wall. It means that the horizontal displacement of anchored retention wall due to excavation is restrained by soldier pile stiffness and jacking force of anchor at the early stage of excavation. lacking force of anchor was mainly influenced on the horizontal displacement of anchored retention wall. The displacements of anchored retention wall and slope soil were affected mainly by rainfall infiltrated from the ground surface. Meanwhile, the horizontal displacement of anchored retention wall with a sloped backside was about $2\~6$ times larger than the displacement of anchored retention wall with a horizontal backside of excavation.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.4
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• pp.239-247
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• 2013

Recently renewable energy such as offshore wind energy takes a higher interest due to the depletion of fossil fuel and the environmental pollution. This paper deals with multi-body dynamics (MBD) analysis technique for offshore wind turbine system considering aerodynamic loads and Thevenin equation used for determination of electric generator torque. Dynamic responses of 5MW offshore wind turbine system are evaluated via the MBD analysis, and the system is the horizontal axis wind turbine (HAWT) which generates electricity from the three blades horizontally installed at upwind direction. The aerodynamic loads acting on the blades are computed by AeroDyn code, which is capable of accommodating a generalized dynamic wake using blade element momentum (BEM) theory. In order that the characteristics of dynamic loads and torques on the main joint parts of offshore wind turbine system are simulated similarly such an actual system, flexible body modeling including the actual structural properties are applied for both blade and tower in the multi-body dynamics model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.330-338
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• 2018

The proportional-integral-derivative(PID) controller has been widely used in the industry because of its robust performance and simple structure in a wide range of operating conditions. However, the AVR(Automatic Voltage Regulator) as a control system is not robust to variations of the power system parameters. Therefore, it is necessary to use PID controller to increase the stability and performance of the AVR system. In this paper, a novel design method for determining the optimal PID controller parameters of an AVR system using the particle swarm optimization(PSO) algorithm is presented. The proposed approach has superior features, including easy implementation, stable convergence characteristic and good computational efficiency. In order to assist estimating the performance of the proposed PSO-PID controller, a new performance criterion function is also defined. This evaluation function is intended to reflect when the maximum percentage overshoot, the settling time are given as design specifications. The ITAE evaluation function should impose a penalty if the design specifications are violated, so that the PSO algorithm satisfies the specifications when searching for the PID controller parameter. Finally, through the computer simulations, the proposed PSO-PID controller not only satisfies the given design specifications for the terminal voltage step response, but also shows better control performance than other similar recent studies.

• Journal of the Korean Society of Marine Environment & Safety
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• v.10 no.2 s.21
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• pp.7-15
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• 2004

To maintain and improve seafarers oral health, I investigated and analyzed the oral health status of seafarers: who are safety training at Korea Institute of Maritime and Fisheries Technology located in Busan. The results of the investigation and analysis are as follows: Two times of brushing teeth a day occupied $51.0\%$ the largest percentage, mixed brushing method was the highest as $39.0\%$, $64.2\% of respondents have recieved teeth scaling. Two or three of times snack intake per day occupied $62.6\%$ the largest percentage. Based on the objects' answer on oral status, the persons answered that my oral status is 'good' $25.9\%$ 'bad' $38.3\%$ occupied The persons with a decayed tooth occupied $78.1\%$ and as for the subjective symptoms of oral disease, $25.6\%$ of respondents answered that I felt sensitivity. Intraoral discomfortable symptoms in the respect of each age, under forty age had dental decay, over forty age had sensitivity of teeth. The more has a intake snack, the more has an oral disease and oral decayed tooth. As a whole of the above results in order to control oral health of the seafarers reasonably, time and economic limiting factors must be solved in the first. In planning oral health education, practicability should be emphasized especially.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.600-606
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• 2016

Seafarers are often placed in circumstances that require emergency evacuations due to various causes, including ship collisions, sinking, stranding, and fires. Achieving shorter evacuation time is an important factor in increasing the survival rate during these circumstances, but the narrow and complicated structure of ships is an obstacle when it comes to executing a quick evacuation. Also, unpredictable restrictions may be imposed by bad sea or weather. In this study, various experiments were conducted with sailors currently on board ships in order to examine factors that increase evacuation time. The data was then and analyzed. Evacuation time was measured by dividing crews into groups: sailors that were given an explanation of the ship's structure and those that were not. Furthermore, the visibility range was divided into 0 m, 3 m, and 5 m. The results indicated that, having an explanation of the ship structure did not have much of an effect on evacuation time but visibility conditions led to an increase in evacuation time with a maximum of 2.5 to 2.6 times longer when the visible distance was 5 m, 0 m and 3 m. Therefore, ensuring a visible distance of over 5 m was determined to be the most important factor for reducing evacuation time. In the future, effort should be made to ensure a greater visible distance to improve the survival rate of seafarers and passengers on board ships that encounter incidents.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.606-614
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• 2020

The administrative ship, Chuja-ho, is the only mode of transportation between manned islands in the Chuja-do, Jeju. Chuja-ho is a 25-year-old age, which is identified to pass the persisting period (25 years) for public ships, and there is an urgent need for a replacement. The residents of the island are also requesting that the new administrative ship be outfitted with medical functions because there is no sea transportation system for medical emergencies in Chuja-do. The purpose of this study is to examine the required functions of a new administrative ship outfitted with medical functions and to suggest a conceptual design. In order to review the necessity of an emergency patient transport system, user requirements were surveyed and analyzed, and the ship's condition assessed by ship experts who carried out an on-site survey and analysis of ship survey data. Thereafter, a conceptual design for a new administrative ship with medical functions was presented. The results of this study can be used during a review of a new budget plan and for basic ship designs during the replacement project by the local government. It is also expected to improve the safety and medical environment of Chuja-do residents.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.689-697
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• 2020

Hazardous and noxious substances (HNS) may cause maritime incidents during marine transportation, which are liable to lead to a large amount of spillage or discharge into the sea. The damage to the marine environment caused by the HNS spill or discharge is known to be much greater than the damage caused by oil spill. Particularly dangerous is HNS, which is deposited or buried in the seabed, as it can damage the organisms that live on, in, and near the bottom of the sea, the so-called "benthos," forming the benthic ecosystem. Therefore, it is vital that the HNS deposited on the seabed be recovered. In order to do so, procedures and equipment are required for accurate detection, stabilization treatment, and recovery of HNS in subsea sediment. Thus, when developing a mechanical recovery system, the performance requirements should be selected using performance indices, and the conceptual design of the mechanical recovery system should be based on performance requirements decided upon and selected in advance. Therefore, this study was conducted to arrive at a conceptual design for a mechanical recovery system for the recovery of HNS deposited on the seabed. In the design of the system, based on the fundamental scenario, the method of suction foundation with the function of self enclosing was adopted for recovering the HNS sediment in the subsea sediment. The mechanical recovery system comprises the suction foundation, pollution prevention, a pump system, control system, monitoring device, location information device, transfer device, and tanks. This conceptual design is expected to be reflected and used in the basic design of the components and shapes of the mechanical recovery system.

• Strategy21
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• s.45
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• pp.5-32
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• 2019

The paper introduces US Indo-Pacific Strategy and discusses its meanings and implications for international security and our strategy. It tries to look at the Indo-Pacific strategy(IPS) through the lenses of international political theories. The paper provides three important observations. First, the US Indo-Pacific strategy is a declaration of the national identity of the US as an Indo-Pacific nation. The paper argues that the IPS reflects the US leadership that would facilitate the formation of, so called, the Indo-Pacific community. In arguing these points, the paper notes that the IPS has rich elements of constructivist approaches including norms and national identity. Second, the paper observes that the IPS report serves as an effective deterrent strategy. The IPS does not call out China as an enemy. But, it tries to deter against a range of actors including China by warning that whoever violates the rules-based order in the region would have consequences. Third, the paper maintains that the IPS is an effort by the US to mitigate the risk of a great power war between the US (an established power) and China (a challenging power) because the IPS articulates the United States's willingness to work with China as long as it plays by the rules. There will be challenges to the US and other countries in the region including South Korea particularly because of economic interdependence. However, the paper argues that the IPS stands for an optimistic sign of the future security in the Indo-Pacific region because it is a manifestation of the US for its national will to defend the status quo characterized as Pax Americana which has been maintained since the end of the Second World War. It also argues that South Korea also can, and should make the most of this opportunity by enhancing our capacity in national defense.

• Journal of Navigation and Port Research
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• v.36 no.6
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• pp.475-480
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• 2012

In order to establish eLoran (enhanced Long Range Navigation) system, it needs the advancement of receiver, transmitter, data channel addition for Loran information, differential Loran sites for compensating Loran-c signal and ASFs (Additional Secondary Factors) database, etc. In addition, the precise synchronization of transmitting station to the UTC (Coordinated Universal Time) is essential if Loran delivers the high absolute accuracy of navigation demanded for maritime harbor entrance. For better timing synchronization to the UTC among transmitting stations, it is necessary to measure and monitor the transmission delay of the station, and the correction information of the transmitting station should be provided to the user's receivers. In this paper we presented the measurement method of absolute delay of Pohang Loran transmitting station and developed a time delay measurement system and a phase monitoring system for Loran station. We achieved -2.23 us as a result of the absolute phase delay of Pohang station and the drift of Loran pulse of the station was measured about 0.3 us for a month period. Therefore it is necessary to measure the delay offset of transmitting station and to compensate the drift of the Loran signal for the high accuracy application of PNT (Positioning, Navigation and Timing).