• Journal of Korea Port Economic Association
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• v.30 no.3
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• pp.59-87
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• 2014

The purpose of this study is to examine the effect of two kinds of Master and Chief Engineer's communication style on group conflicts and members' attitude including job satisfaction and organizational commitment, and to analyze the moderating effect of the isolation from home and community on the relation between the both of communication styles and the several behavioral variables in ship organization. This empirical result demonstrates the fact that Master and Chief Engineer's direct communication with crew has lower conflict and higher job satisfaction and organizational commitment than their indirect one through Chief Officer and First Engineer. In addition, it illustrates the isolation from home only effects moderately on the relation between the communication style and group conflict, and also the direct communication style reduces more the conflict in the group to show less isolation from home. To conclude, this study reveals that job satisfaction and organization commitment could be heightened by proper communication style of Master and Chief Engineer and it would utilize the job performance of ship organization in the long-term.

• Proceedings of KOSOMES biannual meeting
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• 2006.05a
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• pp.41-45
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• 2006

From the 1978 Seasat synthetic aperture radar(SAR) to present systems, spaceborne SAR has demonstrated the capability to image the Earth's ocean and land features over broad areas, day and night, and under most weather conditions. The application of SAR for surveillance of commercial fishing grounds can did in the detection of illegal fishing activities and provides more efficient use cf limited aircraft or patron craft resources. In the area of vessel traffic monitoring for commercial vessels, Vessel Traffic Service (VTS) which uses the ground-based radar system has some difficulties in detecting moving ships due to the limited detection range cf about 10 miles. This paper introduces the field testing results of ship detection by RADARSAT SAR imagery, and proposes a new approach for a Vessel Monitoring System(VMS), including VTS, and SAR combination service.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.551-552
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• 2009

조선산업에서 선박의 건조 과정 중 탑재 공정은 작업자 간의 긴밀한 통신을 필요로 하며 매우 위험한 작업이다. 이러한 작업을 음성 품질이 매우 열악한 무전기나 호접속 지연이 많은 주파수 공용통신(TRS)를 이용하여 통신을 하고 있어 매우 위험하다. 따라서, 이러한 기존 통신방식을 대체하는 IP 기반 그룹통신 시스템과 이에 대한 품질 측정 및 평가가 필요하다. 본고에서는 IP 멀티미디어 시스템의 최초의 서비스인 PoC(PTT over Cellular) 서비스를 기반으로 조선산업에서 통합통신(Unified Communication)을 지향하기 위하여, 강재로 인한 매우 열악한 비가시 거리(NLOS)를 극복하고, 효율적인 통신 서비스를 제공하기 위한 엔터프라이즈 PoC을 기반으로 그룹통신의 품질을 측정하고 평가하였다. WiBro 기반 엔터프라이즈 PoC 서비스는 실제적으로 적용이 가능할 뿐 아니라, 실제의 작업자가 통신할때 지연이 느껴지지 않는 1초 이내의 그룹통신 지연시간에 대해 상기 서비스를 분석하였으며, 이론 상으로는 충분히 제공 가능함을 보이고 있다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.6
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• pp.704-711
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• 2015

In this study, we have conducted a survey of AHP technique through the ocean experts to derive new items and revise assessment items and indices for risk of sunken ships based on the survey results. As a result of the survey, two new items such as accident cause and tidal current are derived. And it shows that existing items such as toxic liquid substance, remaining oil and explosive gas which were evaluated as one group are desirable to be evaluated respectively. Accordingly, we analyze the indices of the new eleven assessment items adjusted from the existing seven assessment items. As a result, the indices are ordered by toxic liquid substance, possibility of leaking, explosive gas, carrying capacity of fuel oil, sensitivity of sea environment, marine traffic environment, cause of accident, tidal current, keel clearance, ship type, and ship size. Especially, as compared with the indices of existing assessment items, the indices of sensitivity of sea environment and possibility of leaking are higher and the index of keel clearance is lower.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2021.11a
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• pp.72-73
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• 2021

As discussions of the International Maritime Organization for the introduction of the Marine Autonomous Surface Ship (MASS) began in earnest, discussions were conducted to prioritize cybersecurity (Cyber Risk Management) when developing a system to support MASS operation at the 27th ENAV Committee Working Group (WG2). Korea launched a technology development project for autonomous ships in 2020, and has been promoting detailed tasks for cybersecurity technology development since 2021. MASS operation in a digital maritime communication system environment requires network security of various digital equipment that was not considered in the existing maritime communication environment. This study introduces the basic concept of network security equipment to support MASS operation in the detailed task of cybersecurity technology development, and defines the network security equipment interface for MASS ship application in the basic stage.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.2
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• pp.172-178
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• 2014

This study suggests the minimum critical external forces based on the assessment of anchoring safety to single anchor situation for representative 8 number of ships in E-group anchorage of Ulsan port. Assessment of anchoring safety is compared holding powers of anchor with external forces of wind, wave and current. Holding powers was reflected materials of seabed, equipment numbers regarding anchor and chain weight, also external forces acting on a hull was calculated considering projected wind area and wetted surface area to the full and ballast conditions respectively. The results of anchoring safety assessments to single anchor showed that the minimum criteria of dragging anchor is a little different from ship's type, size and loading conditions. Bulk carrier can be dragged over the 15m/s of winds and Tanker can be dragged over the 13m/s of winds in case of less than 2knots of currents speed.

• Structural Monitoring and Maintenance
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• v.6 no.4
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• pp.365-387
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• 2019

This study aims to provide useful information on the fatigue assessment of a top-tensioned riser (TTR) subjected to vortex-induced vibration (VIV) by performing parametric study. The effects of principal design parameters, i.e., riser diameter, wall thickness, water depth (related to riser length), top tension, current velocity, and shear rate (or shear profile of current) are investigated. To prepare the base model of TTR for parametric studies, three (3) riser modelling techniques in the OrcaFlex were investigated and validated against a reference model by Knardahl (2012). The selected riser model was used to perform parametric studies to investigate the effects of design parameters on the VIV fatigue damage of TTR. From the obtained comparison results of VIV analysis, it was demonstrated that a model with a single line model ending at the lower flex joint (LFJ) and pinned connection with finite rotation stiffness to simulate the LFJ properties at the bottom end of the line model produced acceptable prediction. Moreover, it was suitable for VIV analysis purposes. Findings from parametric studies showed that VIV fatigue damage increased with increasing current velocity, riser outer diameter and water depth, and decreased with increasing shear rate and top tension of riser. With regard to the effects of wall thickness, it was not significant to VIV fatigue damage of TTR. The detailed outcomes were documented with parametric study results.

• Journal of the military operations research society of Korea
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• v.32 no.2
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• pp.78-91
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• 2006

Recently mass customization has become a new paradigm in the global market to satisfy both the diversified demands of customers but also the efficiency of the mass production system. In this paper, mass customization is embodied by a new product development method with which various product families are produced from standard "product platform" developed from historical data. The product platform, the key concept of this proposed method, is significantly efficient as a solution to the customer demand of high variety and small quantity products. The proposed method is applied to build the platform family of naval ships, utilizing the concept of "Group Technology". In addition, cost effectiveness of the proposed method is analyzed and the applicable range of requirement conditions are presented. In conclusion, some remarkable effects such as reduction in production cost and development time are expected by employing this method to the procurement process of the naval ships.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.7
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• pp.789-796
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• 2012

Radiated noise analysis from a ship structure is a challenging topic owing to difficulties in the accurate calculation of the fluid-structure interaction as well as owing to a massive degree of freedom of the problem. To reduce the severity of the problem, a new fluid-structure interaction formulation is proposed in this paper. The complex frequency-dependent added mass and damping matrices are calculated using the high-order Burton-Miller boundary integral equation formulation to obtain accurate values over all frequency bands. The calculated fluid-structure interaction effects are added to the structural matrices calculated by commercial finite element software, MSC/NASTRAN. Then, the impedance and underwater radiation noise due to an excitation of structure are calculated. The present formulation is applied to a ship to calculate the underwater radiated noise.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.418-430
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• 2014

In this paper, a modelling technique for simulating self-propelled ships in waves is presented. The flow is modelled using a RANS solver coupled with an actuator disk model for the propeller. The motion of the ship is taken into consideration in the definition of the actuator disk region as well as the advance ratio of the propeller. The RPM of the propeller is controlled using a PID-controller with constraints added on the maximum permissible RPM increase rate. Results are presented for a freely surging model in regular waves with different constraints put on the PID-controller. The described method shows promising results and allows for the studying of several factors relating to self-propulsion. However, more validation data is needed to judge the accuracy of the model.