• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.3
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• pp.333-339
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• 2015

Fish exportation using airplanes incurs sizable logistics costs (12,000KRW/kg), according for more than 45% out of the total export cost. Thus, it is unreasonable to quantitatively expand fish exportation by means of air transport. In addition, cases of failing to deliver fish at the right time to the right place occurs frequently due to the limited cargo capacity and insufficient cargo space of airplanes, especially during the peak season. Therefor, a technology that not only minimizes the logistics costs but also transports fish freshly and safely, in the case of long distance exportation to countries such as the United States and Taiwan, should be developed. In this study, a live fish container control system for long distance transportation was designed and implemented. Live flatfish (2,000kg) were selected as the target fish, were transported to the United States to analyze and verify the performance of the a live fish container control ystem and transportation ability.

• Membrane and Water Treatment
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• v.11 no.1
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• pp.1-10
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• 2020

An understanding of particle-particle interactions in filtration requires studying the detachment as well as the attachment of nanoparticles. Nanoparticles captured in a granular media filter can be released by changing the physicochemical factors. In this study, the detachment of captured silver nanoparticles (AgNPs) in granular media filtration was examined under different ionic strengths, ion type, and the presence or absence of natural organic matter (NOM). Filtration velocity and ionic strength were chosen as the physical and chemical factors to cause the detachment. Increasing filtration velocity caused a negligible amount of AgNP detachment. On the other hand, lowering ionic strength showed different release amounts depending on the background ions, implying a population of loosely captured particles inside the filter bed. Overall detachment was affected by ionic strength and ion type, and to a lesser degree by NOM coating which resulted in slightly more detachment (in otherwise identical conditions) than in the absence of that coating, possibly by steric effects. The secondary energy minimum with Na ions was deeper and wider than with Ca ions, probably due to the lack of complexation with citrate and charge neutralization that would be caused by Ca ions. This result implies that the change in chemical force by reducing ionic strength of Na ions could significantly enhance the detachment compared to that caused by a change in physical force, due to a weak electrostatic deposition between nanoparticles and filter media. A modification of the 1-D filtration model to incorporate a detachment term showed good agreement with experimental data; estimating the detachment coefficients for that model suggested that the detachment rate could be similar regardless of the amount of previously captured AgNPs.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.5
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• pp.383-389
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• 2016

In this paper, we present the hull blasting machine with vision-based weld bead recognition device for cleaning shipment exterior wall. The purpose of this study is to introduce the mechanism design of the high efficiency hull blasting machine using the vision system to recognize the weld bead. Therefore, we have developed a robot mechanism and drive controller system of the hull blasting robot. And hull blasting characteristics such as the climbing mechanism, vision system, remote controller and CAN have been discussed and compared with the experimental data. The hull blasting robots are able to remove rust or paint at anchor, so the re-docking is unnecessary. Therefore, this can save time and cost of undergoing re-docking process and build more vessels instead. The robot uses sensors to navigate safely around the hull and has a filter system to collect the fouling removed. We have completed a pilot test of the robot and demonstrated the drive control and CAN communication performance.

• Journal of the Korea Safety Management & Science
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• v.15 no.1
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• pp.51-60
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• 2013

As the human demand or desire on brand new systems otherwise equipped with new functions grows drastically, so does the complexity of the systems. With this trend, the systems are becoming bigger in scale and at the same time the safety requirements are more stringent in the development. Typical systems examples in such a situation may include high-speed railway systems, aero and space systems, marine systems, etc. Failure of those systems can cause serious damages on both the human being and wealth with social infrastructure. As such, it is quite necessary to ensure that the safety requirements be satisfied in the system development. To achieve this need, there could be a lot of solutions to take. In this paper, regarding safety, a special attention is given to the verification phase process, which is one of the intermediate phases of whole systems development process. More specifically, the ultimate concern is placed on how to carry out the design verification while ensuring the safety requirements. To do so, some improvements in the verification phase were proposed first. Then, the outcomes were combined with the systems safety process by generating an integrated process model to reach the goal. As a case study, application to a railway system was discussed, where strict safety requirements are usually necessary. It would be expected that the potential likelihood of failure with rail systems could be reduced if the results obtained are used effectively with some enhancement from further study.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.2
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• pp.188-198
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• 2013

In constructing a collision avoidance system, it is important to determine the time for starting collision avoidance maneuver. Many researchers have attempted to formulate various indices by applying a range of techniques. Among these indices, collision risk obtained by combining Distance to the Closest Point of Approach (DCPA) and Time to the Closest Point of Approach (TCPA) information with fuzzy theory is mostly used. However, the collision risk has a limit, in that membership functions of DCPA and TCPA are empirically determined. In addition, the collision risk is not able to consider several critical collision conditions where the target ship fails to take appropriate actions. It is therefore necessary to design a new concept based on logical approaches. In this paper, a collision ratio is proposed, which is the expected ratio of unavoidable paths to total paths under suitably characterized operation conditions. Total paths are determined by considering categories such as action space and methodology of avoidance. The International Regulations for Preventing Collisions at Sea (1972) and collision avoidance rules (2001) are considered to solve the slower ship's dilemma. Different methods which are based on a constant speed model and simulated speed model are used to calculate the relative positions between own ship and target ship. In the simulated speed model, fuzzy control is applied to determination of command rudder angle. At various encounter situations, the time histories of the collision ratio based on the simulated speed model are compared with those based on the constant speed model.

• Fire Science and Engineering
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• v.17 no.4
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• pp.28-35
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• 2003

To analyze the transfer characteristics of $CO_2$ extinguishant when extinguishant is injected into a closed space similar to a marine engine room, a numerical simulation was performed. Flow and Concentration fields are calculated according with the variation of the fire plume,s location. The results show that tile variation of fire plumes, location greatly effected on the flow patterns and the characteristics of $CO_2$ extinguishant transfer. In case of the fire plume located at left region of the 2nd floor center in the engine room consisted of first and second floor, The effects similar to the air curtain is found and cut off the mass transfer. In the characteristics with hight, the iso-concentration line below the extinguishable limit is formed in the left region of the 1st and 2nd floor center after the $CO_2$ extinguishant is completely injected. therefore I think that the results of this study are considered to arrange the $CO_2$ injection nozzles for the $CO_2$ fire fighting equipments.

• Journal of National Security and Military Science
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• s.2
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• pp.121-163
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• 2004

Science technique development expanded into, not only land, sea, and air operations but also those of airspace, and cyber battle spaces. It is generally accepted at this time that space centric operations currently cannot be effectively divided from air operations. However, science and technology advancements make it possible to integrate Army, Navy, Airforce, and Marine forces into effective operations as never before. The Republic of Korea Armed Forces needs to establish a more effective joint concept. The US military, considered by many experts as the most effective in the world, understands the necessity of joint operations and accordingly has highly developed its own concept of joint operations. The US joint operational concepts demonstrated their effectiveness during the Iraqi War by dominating the battlefield through effective use of all combat and non-combat power. Following the US Iraqi War experience, the US Department of Defense continued to enhance Joint Capability through the acceleration of US Military Transformation involving all components. The future national security of the Republic of Korea, faced with the peculiarity of communist threat in the form of North Korea, and the conflicting interest of four strong powers; the United States, China, Japan, and Russia, depends on small but strong armed forces employing all available combat power through effective National and Military Strategy, and considering domestic and international constraints. In order to succeed in future wars, military operations following joint operational concepts must effectively employ all available combat power in a timely manner. The Republic of Korea Armed Forces must establish a joint forces concept in order to integrate all available combat power during employment. Therefore we must establish military operations that develop the military structure and organization, doctrine, weapon systems, training and education of our armed forces based on the key concept of joint operations.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1037-1040
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• 2008

In order to predict the remaining life of marine concrete structures under climatic loads, it is necessary to develop an analytical approach to predict the time and space dependent deterioration of concrete structures due to mainly chloride attack up to corrosion initiation and additional deterioration like cracking of cover concrete. This study aims to introduce FEM model for life-time simulation of concrete structures subjected to chloride attack. In order to consider uncertainties in materials as well as environmental parameters for the prediction, Monte Carlo Simulation is integrated in that FEM modeling for reliability-based remaining service life prediction. The paper is organized as follows: firstly general scheme for reliability-based remaining service life of concrete structures is introduced, then the FEM models for chloride penetration, corrosion product expansion and cover cracking are briefly explained, finally an example is demonstrated and the effects of localization of chloride concentration and corrosion product expansion on service life using above model are discussed.

• Korean Journal of Construction Engineering and Management
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• v.12 no.2
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• pp.12-20
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• 2011

Recently, construction site scale has been growing larger along with the growth of national economy. As construction market requires time reduction, cost saving, and improving quality, a cutting-edge technology applied research has been gradually studied for more efficient project management. In particular, the Real Time Location System (RTLS) technology, a real-time location tracking system of construction resources, can be effectively used in safety management. This technology has been studied and applied in various industries including architectural, marine, urban, and other industries. However, although tunnel construction in civil engineering has a narrow space and many safety risks, there are not researched about this content. Therefore, this study proposes an advanced safety management model for tunnel construction using the RTLS technology and a measurement method of the feasibility of this model in the construction site.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.11 s.114
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• pp.1105-1111
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• 2006

In this paper, using low-temperature co-fired ceramic(LTCC) based system-in-package(SiP) technology, a very compact power amplifier LTCC module was designed, fabricated, and then characterized for 60 GHz wireless transmitter applications. In order to reduce the interconnection loss between a LTCC board and power amplifier monolithic microwave integrated circuits(MMIC), bond-wire transitions were optimized and high-isolated module structure was proposed to integrate the power amplifier MMIC into LTCC board. In the case of wire-bonding transition, a matching circuit was designed on the LTCC substrate and interconnection space between wires was optimized in terms of their angle. In addition, the wire-bonding structure of coplanar waveguide type was used to reduce radiation of EM-fields due to interconnection discontinuity. For high-isolated module structure, DC bias lines were fully embedded into the LTCC substrate and shielded with vias. Using 5-layer LTCC dielectrics, the power amplifier LTCC module was fabricated and its size is $4.6{\times}4.9{\times}0.5mm^3$. The fabricated module shows the gain of 10 dB and the output power of 11 dBm at P1dB compression point from 60 to 65 GHz.