• Transactions of the Korean hydrogen and new energy society
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• v.34 no.1
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• pp.26-31
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• 2023

In this study, in order to propose a modular method for type IV high aspect ratio modular hydrogen storage vessel, a numerical analysis was conducted on the heat transfer behavior in series and parallel connection methods, and the differences according to each connection method were reviewed. Computational fluid dynamics software was used to check the internal temperature and pressure values of the hydrogen storage container under charging conditions. In terms of thermal safety when charging hydrogen gas, it was confirmed that the parallel modularization method was superior.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.3
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• pp.7-13
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• 2019

Recently, an automobile market used to natural gas has emerged as fast-growing as the several countries, who holds abundant natural fuel resources, has promoted to supply the national agency for an automobile car. LNG fuel vessel is more efficient in another way as the energy density is high, but it requires a high technology and investment to maintain extreme low temperature. CNG fuel vessel are relatively low-cost alternative to LNG, but poorly economical in terms of energy density as well as showing safety issues associated with compressed pressure. The development of adsorbed natural gas (ANG) has emerged as one of potential solutions. Therefore, it is desirable to reduce the weight of vessel by applying light-weighed a composite carbon fiber in order to response to the regulation of $CO_2$ emission. Herein, this study make the prototype ANG vessel not only based on the optimal design and analysis of material characteristic but also based on the shape design, and it suggest a new type for the composite carbon fiber vessel which verified functional test. Moreover, the detail shape design is analyzed by a finite element analysis, and its verifies the ANG vessel.

• Journal of Ocean Engineering and Technology
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• v.21 no.6
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• pp.1-6
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• 2007

A study on the new active circulation type oil-water separation system including buoyancy type guidance system was carried out in this paper. Newly developed oil-water separation system is composed of several oil separation steps. In the beginning of these steps, buoy type separation system would be used. Buoy type oil guiding system was developed based on the difference of density of water and oil.

• Journal of the Korean Institute of Gas
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• v.24 no.6
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• pp.61-69
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• 2020

This paper is a study of the behavior characteristics that occur in the hydrogen storage vessel TYPE 1 according to pressure and temperature conditions by FEM(Finite element method). Von Mises stress (VMS) generated at the highest pressure was compared with Yield strength (YS) of the material for structural safety assessment of the container, and the results of plastic strain energy density (PSED) were analyzed as basic data for life expectancy. According to the analysis results, the safety of the hydrogen gas storage vessel is not ensured due to the occurrence of VMS higher than the yield strength on the bottom of the storage container at a gas pressure of 40 Mpa or higher. In addition, the results of VMS caused by temperature conditions are very low and the behavior by temperature can be ignored. The maximum pressure of VMS/YS below 1 is calculated to be about 30 Mpa, indicating that the hydrogen storage container subject to this paper should be managed with a gas charging pressure of less than 30 Mpa.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.3
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• pp.524-531
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• 2011

The cryogenic vessel, storing a liquified solutions as LOX and $LN_2$, consists of a external vessel, internal vessel, thermal insulator and internal support. The internal support should be satisfied with mechanical strength not only to support weight of internal tank but also to maintain uniform space between external and internal tank in spite of external mechanical shock. However, excessive structure design of internal supports is able to increase the amount of heat conduction and the rate of vaporization. The thermal insulator, filled with space between a external and internal vessel, reduces the rate of heat transfer and guarantees the standing time of cryogenic vessel. Especially powder type of insulator has low thermal conductivity and reduce the specification of structure design. In order to evaluate the effect of insulator on structure design, the experiment set-up simulated cryogenic vessel was tested in shock environment according to thermal insulator. As a result, the behavior of internal support under external shock was understood and the design criteria was able to be suggested.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.1
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• pp.98-118
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• 2014

An auto weather-vaning system for a Dynamic Positioning (DP) vessel is proposed. When a DP vessel is operating, its position keeping is hindered by ocean environmental disturbances which include the ocean current, wave and wind. Generally, most ocean vessels have a longitudinal length that is larger than the transverse width. The largest load acts on the DP vessel by ocean disturbances, when the disturbances are incoming in the transverse direction. Weather-vaning is the concept of making the heading angle of the DP vessel head toward (or sway from) the disturbance direction. This enables the DP vessel to not only perform marine operations stably and safely, but also to maintain its position with minimum control forces (surge & sway components). To implement auto weather-vaning, a nonlinear controller and a disturbance observer are used. The disturbance observer transforms a real plant to the nominal model without disturbance to enhance the control performance. And the nonlinear controller deals with the kinematic nonlinearity. The auto weather-vaning system is completed by adding a weather-vaning algorithm to disturbance based controller. Numerical simulations of a semi-submersible type vessel were performed for the validation. The results show that the proposed method enables a DP vessel to maintain its position with minimum control force.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.4
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• pp.97-103
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• 2017

The objective of this study is to develop and commercialize an on-board fuel storage system for CNG vehicles. A type 4 vessel is made of resin-impregnated continuous filament windings on a polyamide (PA6) liner. In particular, this study localized the PA6 liner's fabrication and development. To analyze the filament winding, a specimen test was performed, and the results were verified values obtained using finite element analysis. In this study, the filament winding and fibers were optimized for a 207 bar composite cylinder in a compressed natural gas vehicle.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.2
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• pp.183-187
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• 2011

As larger the commercial vessel is, and rougher the marine environment becomes nowadays, drag embedment type anchor (DEA) of more stable performance and higher holding power is requested to be applied on the vessel. But, the performance of DEA has not become well known to academy and industries so far, that the basic study of DEA performance and holding force for the development of new DEA of higher performance is insufficient that required. In this paper, three types of same holding category DEA model (HALL, AC-14, POOL-N, scale 1/10), which are generally applied on the commercial vessel nowadays, were tested by being horizontally dragged on the test tank, on which sand was being floored with sufficient depth, and measured the holding force of each anchor simultaneously using load cell and D/A converter. With the test results, the embedding motion was analyzed to have three different stages and the holding force of each anchor was analyzed with respect to the anchor geometry, such as shape and weight of each type of anchors, and final embedding depth.

• Journal of Power System Engineering
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• v.16 no.2
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• pp.66-74
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• 2012

In this paper, the authors propose a new approach to control a barge type surface vessel. It is based on the Dynamic Positioning System(DPS) design. The main role of barge ship is to carry and supply the materials to the floating units and other places. To carry out this job, it should be positioned in the specified area. However sometimes the thrust systems are installed on it, and in general the rope control by mooring winch system is used. It may be difficult to compare the control performances of two types. If we consider this problem in point of usefulness, we can easily find out that the winch control system is more useful and applicable to the real field than the thrust control system except a special use. Therefore, in this paper we consider a DPS design problem which can be extended to the many application fields. The goal of this paper is twofold. First, the sliding mode controller (SMC) for positioning the our vessel is proposed. Especially, in this paper, a robust stability condition is given based on descriptor system representation. In the result, the sliding mode control law guarantees to keep the vessel in the defined area in the presence of environmental disturbances. And second, the thrust allocation problem is solved by using redistributed pseudo-inverse (RPI) algorithm to determine the thrust force and direction of each individual actuator. The proposed approach has been simulated with a supply vessel model and found work well.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.5
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• pp.120-125
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• 2015

This research aims to increase the reliability and reproducibility of the ambient cycling test by properly making corrections to the test procedure. The vessel (106 L) is initially filled with 70 L of water and horizontally placed on a balance. The pressure range inside the vessel varies from 2.5 to 25.9 MPa at the frequency of 6 cycles per minute. After reviewing the results, there was a temperature difference of approximately $10^{\circ}C$ between the air pocket and the water, and the upper part of the liner faced a repeated temperature change of $40^{\circ}C$. It is possible for the aluminum liner of the composite vessel to be damaged by such a sharp change in temperature. Additionally, as a result, no pass having anything to do with the purpose of the test would occur. Therefore, it is suggested that the air pocket be completely removed.