• 한국지반신소재학회논문집
• /
• 제14권3호
• /
• pp.21-29
• /
• 2015

인공어초는 해양환경을 개선하고 어류와 해양생물들에게 주거지를 제공하는 인공 수중 구조물이다. 특히 인공어초가 느슨한 모래, 연약한 점성토와 같은 연약지반에 설치될 경우 인공어초의 자중에 의해 인공어초의 침하가 발생하게 된다. 본 연구에서는 관입실험을 통해 토목섬유 보강 넓이에 따른 인공어초의 지지력 보강효과를 확인하였고, 실내 대형 토조 실험을 통해 침하 저감효과를 확인하였다. 관입실험과 실내 대형 토조 실험을 통해 지오그리드와 같은 토목섬유를 인공어초 하부에 포설하게 되면 지지력이 증가하며, 침하가 감소하는 경향을 나타내었다.

• 한국생산제조학회지
• /
• 제26권1호
• /
• pp.74-81
• /
• 2017

A crane is typically used as a means to lift and load equipment or materials. A surface vessel uses a towed object for underwater activity. Such a mechanism for dropping and lifting of equipment is necessary, and is called an overboarding unit. The present study is focused on the overboarding unit used for a crane structure. This paper deals with new overboarding mechanism design and GA-based $MATLAB^{(R)}$ optimization. By using a quadrilateral link mechanism, it is possible to set the constraint function for optimizing the GA method. The optimization with $MATLAB^{(R)}$ is followed by the $SolidWorks^{(R)}$ simulation and verification. When applying the proposed mechanism, the operator is expected to have a big advantage in safety and efficiency of operations. Furthermore, the technology developed in this study will be helpful in similar circumstances and in the proposed mechanism.

• 수산해양기술연구
• /
• 제46권1호
• /
• pp.20-31
• /
• 2010

In this research, the submersible fish cage was designed to avoid structural and biological damage during harsh sea conditions. The submersible cage system consists of netting, mooring ropes, a floating collar, floats, sinkers and anchors. Whole elements of the cage were modeled on the mass-spring model. The computer simulations were carried out to investigate the dynamic behavior of the cage and to calculate mooring line tension subjected to tidal currents and waves. As expected, the tension values in the mooring line of the submerged position are 36% less compared to that of the surface cage under the same loading conditions. As the wave was used in combination with the current velocity of 1m/s, the average tensile load for the submerged cage showed 85% of the value for the floating cage. The simulation results provide an improved understanding of the behaviors of the structure and valuable information on the optimized design of the cage system exposed to open ocean environmental factors.

• 한국군사과학기술학회지
• /
• 제18권5호
• /
• pp.594-601
• /
• 2015

The purpose of this research is to propose a maintenance support system for deciding assembly sequence of the product and appropriate tools that are used to assembly and disassembly of parts in the product when geometric properties of the product. The digital maintenance system (DMS) is developed to generate the maintenance guideline and the initial experiment is conducted especially for an underwater weapon system with cylindrical structure. DMS considers four factors to find the efficient assembly and disassembly procedure automatically: (1) assembly tree, (2) properties of each part, (3) distance from the center of the product, and (4) volume. Based on the factors, DMS simulate the movement of each tool virtually and the properties of tools are investigated to find an appropriate tool for using assembly and disassembly of each part in the product. The proposed approach integrates modeling, simulation, data configuration, and virtual reality to allow a development of preliminary maintenance guidance.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2016년도 춘계학술대회
• /
• pp.93-95
• /
• 2016

최근 물동량 하락으로 인해 선박의 에너지 절감에 대한 선주들의 관심이 모아지고 있다. 선박용 HVAC은 선박 구조상 거주구역이 수밀형 창문으로 구성되고 폐쇄적이기 때문에 승무원의 쾌적한 환경 조성을 위해 사용된다. 또한 생활수준의 향상과 더불어 승무원들의 쾌적함에 대한 요구는 더욱 강해지고 있어 HVAC의 기능 향상이 요구되고 있다. 따라서 본 논문에서는 변풍량 방식의 선박용 HVAC 구조를 사용하여 HVAC 제어기능 향상 및 에너지를 절감할 수 있는 방법을 제시한다.

• 상하수도학회지
• /
• 제24권6호
• /
• pp.713-722
• /
• 2010

This paper has assessed the flow patterns and settling efficiency in the sedimentation basin using the particle tracking method of the CFD code and has reached the following conclusions: In the original design where no baffle is installed in the sedimentation basin, a large recirculating area where the flow stagnates is created in the right side of the sedimentation basin, with most of the particles moving to the left side of the sedimentation basin following the flow. This biased flow structure in the sedimentation basin reduces the residence time of particles and thereby undermines settling efficiency. The biased flow toward the left side of the sedimentation basin is alleviated by installing a baffle in the sedimentation basin, promptly reducing the fast flow of over 0.7 m/s in the inlet of the sedimentation basin to the rate below 0.2 m/s. In this paper's simulation conditions, if a one-sided baffle is to be installed in the sedimentation basin, placing it 15 meters away from the basin's inlet leads to the best settling efficiency; it has also been analyzed that installing a two-sided baffle-rather than a one-sided one-is a better option in terms of settling efficiency. The highest settling efficiency of 96.2% is achieved when the underwater length of the two-sided baffle is set at 8 meters.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 춘계 학술발표회
• /
• pp.338-350
• /
• 2010

As existing materials for ground reinforcement, chemical grout material using cementitous materials and waterglass was used. But many problems in terms of ground reinforcement effects were implicated. In this study, for development and applicability verification of new materials, viscosity, fluidity, permeability, Self-Leveling, keeping of drilled hole, antiwashout underwater, resistance of water (groundwater dilution and minimize material eluting) and the early strength and long-term strength characteristics of developed materials was confirmed, and material standards, and establishing construction standards for the various model tests were conducted. As a result, high viscosity, flowability, permeability and keeping of drilled hole characteristics are excellent, in addition to the early strength properties, dilution does nat occur to groundwater, including groundwater is available for dealing with environmental issues. Application of basic and reinforcement method by Filler function in addition to structure can also or development of a new concept can be expected. In addition, middle and large-diameter drilled shaft, micropile, ground anchors, soil-nailing, steel pipes multi-grouting reinforcement for cement injection process could be used enough to even be considered.

• Journal of Advanced Marine Engineering and Technology
• /
• 제32권6호
• /
• pp.989-996
• /
• 2008

Recently, a few types of fish-cage in open sea are researched. This fish-cage has to operate monitoring system for keeping an optimum living condition for fish. The most efficient monitoring system is WVMS(Wireless Vision Monitoring System) for fish-cage in open sea. WVMS should be able to transmit video signal and communicate with each controller. So. it needs to be based on WLAN(Wireless LAN) which has characteristic of higher transfer-rate, In this paper, we propose a structure of WVMS using WLAN equipments for maritime environment and prove its effectiveness. We present the propagation loss model of WVMS's communication channel. measured by field test, and discuss its validity compared with the predictive value based on the Friss propagation model and Plane earth reflection model. We present the number of frames that is received from WLAN modem connecting with underwater-camera in field test spots. As a result, we confirmed that proposed WVMS is suitable for maritime environment and it is possible to be applied to fish-cage in open sea on 'seogwipo'.

• 대한조선학회논문집
• /
• 제52권4호
• /
• pp.283-289
• /
• 2015

RGT(Riser Guide Tube) is a part of mooring on the bottom of a turret system to be connected with a production riser, and DBSC(Diverless Bend Stiffener Connector) is a latching component between them. In this paper, appropriate lug arrangement is decided mathematically for the case that a DBSC is lifted and installed on a RGT under the water while FPSO is under construction. Considering asymmetric arrangement & position of RGT and initial lug position, additional lug positions are determined by using an optimization method. The modified installation scheme with new lug points is investigated with a lifting simulation system, SIMSON. The simulation result shows that the installation of DBSC on RGT under the given conditions is quite feasible; therefore the mathematical method is proven to be appropriate.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
• /
• pp.331-334
• /
• 2006

This paper deals with the ways how the AUV is composed of sub-modules to be fault-tolerant during the mission. The emergency situations can be classified into several parts according to the zones where the situations take place - sensor zone, actuator zone, interpreter zone, and communication zone. This paper explains how each element of emergency situation is detected, contained and treated, and as a result, introduce the modular structured AUV controller for the autonomous cruising.