• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.4
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• pp.466-475
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• 2010

This study intends to present a direction for the better reforming of fishers'onboard living conditions and proposals for preparing for ratification of the Work in Fishing Convention by means of making a comparison between standards on recent national fishing vessel accommodation facilities and standards on the Work in Fishing Convention and Its Recommendation, 2007, ILO. For the most part of standards on national fishing vessel accommodation facilities are somewhat insufficient to satisfy the provisions in Annex III of the Convention. Considering by items on fishing vessel accommodation facilities, the standards on insect protector, noise and vibration, heating and air conditioning, lighting, persons per sleeping room, recreational facility are not provided in national law. Headroom, separation of accommodation, sleeping room floor area, mattress size, mess room, galley and food storage are partially sufficient for the Convention. In case of sanitary facilities, national standards are not sufficient for the Convention. The other side, facilities related safety of ship and crew such as emergency escape etc., are fully sufficient for the Convention. These insufficiencies caused by different types of fishing vessel depend on originality of fishing method and practices. In the comparison between equivalent tonnage about vessel's length on convention and calculated tonnage of national existing fishing vessel, the difference are 226tons about length 24m and 501tons about length 45m. For that reason, headroom, persons per sleeping room, cabin of sicker and injured, sanitary facilities may decide to use gross tonnage in place of length (L) and the alleviating measure basis of convention. But in case of standards on sanitary facilities which are unsufficient for the Convention, specially in coastal fishing vessel length basis should be adopted with alleviating basis for less than length 24m.

• Special Issue of the Society of Naval Architects of Korea
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• 2013.12a
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• pp.35-41
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• 2013

Nowadays, automated modeling system for steel margin based on interactive user interface has been developed and applied to the production design stage. The system could increase design efficiency and minimize human error owing to recent CAD technique. However, there has been no approach to the pre-nesting design stage at all in early modeling process especially where ship model should be handled at more than two design stages using AVEVA Marine. A designer of the design stage needs artificial intelligence system beyond modeling automation when 3D model must be prepared in early modeling process using AVEVA Marine because they have focused on 2D nesting traditionally. In addition, they have a hard time figuring out the model prepared in previous design stage and modifying the model for steel purchase size in early modeling process. In this paper, artificial intelligence modeling system for automated application of steel margin in early modeling process using AVEVA Marine is developed in order to apply to the pre-nesting design stage that can detect effective segments before a calculation to find if a segment locates near block butt boundaries by filtering noise segments among lines, curves and surface intersections based on IT big data analysis.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.3
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• pp.297-307
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• 2020

In the study, energy flow analysis is performed to predict the performance of silencers. To date, deterministic approaches such as finite element method have been widely used for silencer analysis. However, they have limitations in analyzing large structures and mid-high frequency ranges due to unreasonable computational costs and errors. However, silencers used for ships and off-shore plants are much larger than those used in other engineering fields. Hence, energy governing equation, which is significantly efficient for systems with high modal density, is solved for silencers in ships and off-shore plants. The silencer is divided into two different acoustic media, air and absorption materials. The discontinuity of energy density at interfaces is solved via hypersingular integrals for the 3-D modified Helmholtz equation to analyze multi-domain problems with the energy flow boundary element method. The method is verified by comparing the measurements and analysis results for ship silencers over mid-high frequency ranges. The comparisons confirm good agreement between the measurement and analysis results. We confirm that the applied analysis method is useful for large silencers in mid-high frequency ranges. With the proven procedures, energy flow analysis can be performed for various types of silencer used in ships and off-shore plants in the first stage of the design.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.4
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• pp.8-16
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• 1993

Auto-Pilot System uses heading angle information via the position sensor and the rudder device to control the ship direction. Most of the control logics are composed of the state estimation and control algorithms assuming that the measurement device and the actuator have no fault except the measurement noise. But such asumptions could bring the danger in real situation. For example, if the heading angle measuring device is out of order the control action based on those false position information could bring serious safety problem. In this study, the control system including improved method for processing the position information is applied to the Auto-Pilot System. To show the difference between general state estimator and F.D.F., BJDFs for the sensor and the actuator failure detection are designed and the performance are tested. And it is shown that bias error in sensor could be detected by state-augmented estimator. So the residual confined in the 2-dim in the presence of the sensor failure could be unidirectional in output space and bias sensor error is much easier to be detected.

• The Journal of the Acoustical Society of Korea
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• v.27 no.1
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• pp.40-46
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• 2008

Weak target detection and localization in the presence of loud surface ship noise is a critical problem for matched field processing (MFP) in shallow water. For stationary sources, each signal component of received signal can be separated and interference can be suppressed using eigen space analysis schemes. However, source motion, in realistic cases, causes spreading of signal energies in their subspace. In this case, eigenvalues of target and interfere signal components are mixed and hard to be separated with usual phone space eigenvector decomposition (EVD) approaches. Our technique is based on mode space and utilizes the difference in their physical characteristics of surface and submerged sources. Performing EVD for modal cross spectral density matrix, interference components in the mode amplitude subspace can be classified and eliminated. This technique is demonstrated with synthetic data, and results are discussed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.2
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• pp.130-140
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• 2022

Recently, wideband acoustic technology has been introduced and started to be used in fisheries acoustic surveys in various waters worldwide. Wideband acoustic data provides high vertical resolution, high signal-to-noise ratio and continuous frequency characteristics over a wide frequency range for species identification. In this study, the main characteristics of wideband acoustic systems were elaborated, and a general methodology for wideband acoustic data analysis was presented using data collected in frequency modulation mode for the first time in Republic of Korea. In particular, this study described the data recording method using the mission planner of the wideband autonomous acoustic system, wideband acoustic data signal processing, calibration and the wideband frequency response graph. Since wideband acoustic systems are currently installed on many training and research vessels, it is expected that the results of this study can be used as basic knowledge for fisheries acoustic research using the state-of-the-art system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.5
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• pp.321-328
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• 2015

In recent years, there has been an increasing demand to apply the new IACS(International Association of Classification Societies) standards for ice and polar-classed ships. For ice-class vessel propulsion system, the ice impact torque design criterion is defined as a periodic harmonic function in relation to the number of the propeller blades. However, irregular or transient ice impact torque is assumed to occur likely in actual circumstances rather than these periodic loadings. In this paper, the reliability and torsional vibration characteristics of a comparatively large six-cylinder marine diesel engine for propulsion shafting system was examined and reviewed in accordance with current regulations. In this particular, the transient ice impact torque and excessive vibratory torque originating from diesel engine were interpreted and the resonant points identified through theoretical analysis. Several floating ice impacts were carried out to evaluate torque responses using the calculation method of classification rule requirement. The Newmark method was used for the transient response analysis of the whole system.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.3
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• pp.133-139
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• 2020

In order to study the resistance test technique for the submerged body in Large Cavitation Tunnel (LCT), DARPA Suboff, submarine model publicly available was manufactured. DTRC released the resistance test data of DARPA Suboff conducted at ship speeds up to 18.0 knots in high-speed towing tank in 1990. As LCT is considered restricted waterways with walls, the resistance test results must be corrected with three wall blockage effects called buoyancy effect, solid blockage effect and wake blockage effect. Before correction, the resistance of LCT was 16~20 % higher than that of DTRC. After correction, the resistance and the resistance coefficients were compared with those of DTRC. The corrected resistance of LCT shows good agreement with that of DTRC. The residual resistance coefficient shows the difference according to the calculation method of buoyancy and frictional resistance coefficient. This paper suggests the best way for the calculation of residual resistance coefficient, On the basis of the present study, it is thought that the operating conditions for the propeller cavitation and noise tests can be drawn through LCT tests.

• Journal of Internet Computing and Services
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• v.23 no.3
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• pp.57-65
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• 2022

International attempts to smuggle narcotics and explosives using ship or aircraft cargoes are on the rise. With the recent increase in the number of detection cases of narcotics and explosives in Korea, it is important to detect dangerous material (narcotics and explosives) through container searches at ports and airports, which are the main routes. This paper proposes a technique to detect dangerous material in cargo containers using the sampled output signal of ion mobility spectroscopy (IMS). The proposed technique estimates parameters such as a threshold, a window length, and a noise level for ion detection of the target dangerous material by using known materials in the initialization stage. The estimated parameters are used to detect the ions of the dangerous target material inside the containers. The proposed technique can be applied when the peak value of the IMS signal and the ion mobility are varying due to container environments.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.3
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• pp.185-198
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• 2022

Purpose : We conducted a study to propose comparing subjective sleeping states data that was collected through scientifically measuring by using smartwatch and surveys for seafarers. In addition, we conducted a study to provide sleep though analysis of the environmental factors that influence the sleep efficiency of seafarers. Methods : For scientific measurement of seafarers' sleeping states, we measured the sleep hours and sleep efficiency for at least 3 days by using the healthcare function of smartwatches which are wearable devices. As for subjective sleeping states, we collected data on sleep hours and satisfaction rates on the quality of sleep through a survey. Lastly, as for the environmental factors that affect the sleep efficiency which is measured by smartwatches such as physical environment, bedroom space, bedroom furniture, bedding, a survey by self-evaluation method was conducted. Results : There were significant differences in the scientific sleep hours measurement values for all seafarers and the average sleep hours in the subjective survey. There were significant differences in the scientific sleep efficiency measurements of all the seafarers and the sleep satisfaction of the subjective survey, and there was no correlation between the scientific sleep efficiency and the subjective sleep satisfaction of all the seafarers. Among the environmental factors affecting the sleep efficiency of the seafarers, humidity variable had the most influence, and vibration and illuminance variables were also shown to have a very significant effect. Conclusion : We propose the measuring method that can analyze the quantitative and qualitative sleep states of the seafarers by using small activity recorders. In addition, it is very important to control humidity, vibration, and illuminance among ship environmental factors, and comfort, noise and bedroom size should also be reflected.