Busan, South Korea
Busan, South Korea

Time filter

Source Type

Jang S.-K.,Mokpo Maritime University | Park J.-C.,Korean Register of Shipping | Jeong J.-Y.,Mokpo Maritime University | Han M.-S.,Mokpo Maritime University | Kim S.-J.,Mokpo Maritime University
Science of Advanced Materials | Year: 2014

The reliability for offshore structures is very important since they operate under harsh operating conditions for a long time. Material damage in seawater involves not only physical damage due to cavitation but also corrosion damage by Cl- ions; thus, seawater deteriorates the mechanical performance and lifetime of a ship's components. This study investigated the protection potential of ALBC3 alloy to minimize the cavitation-induced damage by employing the hydrogen overvoltage phenomenon. To achieve this, a hybrid potentiostatic apparatus was devised for the characterization of electrochemical properties of the alloy with cavitation. A cavitation experiment was conducted at 30 μm of amplitude by using an ultrasonic vibratory generator in accordance with modified ASTM G32 regulation. Consequently, the optimum potential range to enhance the cavitation resistance is considered to lie between -2.8 V and -2.2 V, which corresponds to the activation polarization range. © 2014 by American Scientific Publishers.


Cho S.-R.,University of Ulsan | Kim H.-S.,Hyundai Heavy Industries | Doh H.-M.,Korean Register of Shipping | Chon Y.-K.,Korean Register of Shipping
Ships and Offshore Structures | Year: 2013

A robust ultimate strength formulation is proposed for stiffened plates subjected to combined axial compression, transverse compression, shear force and lateral pressure loadings. Before deriving the formulation, a simplified numerical method was developed to trace the structural behaviour of stiffened plates under combined loadings. A rigorous parametric study was then performed using the developed numerical method to predict the ultimate strength of various stiffened plates under various combinations of loadings. The formulation was derived by a regression study using the parametric study results. The accuracy and reliability of the proposed formulation were compared with those of commercial packages, such as ABAQUS and DNV PULS, and experimental results. © 2013 Taylor & Francis.


Oh H.,Korean Register of Shipping | Kim B.,Jeju National University
Energy | Year: 2015

After a wind farm construction is completed, the power performance guaranteed by the wind turbine manufacturer is usually verified based on the international standard IEC61400-12-1. Because of an insufficient project budget and the constraint on the minimum separation distance of the meteorological mast from the installed wind turbines, it is a common practice to verify the power performance of one representative wind turbine and apply the result as the reference power performance guarantee for all the wind turbines. In this study, the power performances of five wind turbines operating at a commercial wind farm located on complex terrain were measured and analyzed. The results showed large power performance differences between the turbines. Because the power performance of one representative wind turbine cannot guarantee the power performances of all the wind turbines in a wind farm located on complex terrain, we submit that it is necessary to carry out power performance verifications on many or all of the wind turbines. © 2015 Elsevier Ltd.


Yun S.,Inha University | Kim J.,Inha University | Lee K.-S.,Korean Register of Shipping
International Journal of Precision Engineering and Manufacturing | Year: 2010

Cellulose has been discovered as a smart material that can be used as sensor and actuator material. In this paper, cellulose smart material termed as electro-active paper (EAPap) is prepared by an automated process that includes tape casting and zone stretching. To evaluate characteristics of the EAPap, its Young's modulus and piezoelectric charge constant are measured depending on the orientation angle, in comparison with the manually fabricated EAPap results. The zone stretching method can effectively align the cellulose fibers in the EAPap so as to improve its Young's modulus as well as piezoelectric charge constant. The 0 degree oriented sample shows its maximum Young's modulus and the 45 degree oriented sample exhibits the maximum piezoelectric charge constant. This 45 degree is associated with its shear piezoelectricity. The actuator performance of EAPap is evaluated by measuring its bending displacement depending on the orientation angle and the excitation voltage. The 45 degree oriented sample exhibits the maximum bending displacement. Details of the material preparation, the automation process, characterization and the actuator performance are addressed. This automated process that includes tape casting and zone stretching is suitable for mass production of the EAPap. © KSPE and Springer 2010.


Lee S.,Korean Register of Shipping | Chu B.,Korea Advanced Institute of Science and Technology | Chang D.,Korea Advanced Institute of Science and Technology
International Journal of Precision Engineering and Manufacturing | Year: 2014

To achieve drilling safety, a risk-based design of the dolly assembly control system is proposed. The risk and cost-benefit assessments are conducted to obtain information needed to make decisions about the safe design of the system. A failure modes and effects analysis (FMEA) is performed to identify and analyze the plausible hazardous scenarios by determining the failure modes of the subcomponents and their effects on the system operation. The priorities of risks are ranked by assigning a risk priority number for further investigation. Appropriate recommendations are made as risk reduction measures to achieve a more intrinsically safe design. A subsequent fault-tree analysis (FTA) is performed to provide a more quantitative risk evaluation. Monte Carlo simulations (MCSs) are conducted to determine the change of the availability between the original design and a system with recommendations adopted. For the sake of decision making, a cost-benefit assessment is performed, which demonstrated that the suggestions provided in this study are highly justifiable and strongly recommendable. © 2014, Korean Society for Precision Engineering and Springer-Verlag Berlin Heidelberg.


Kim S.-J.,Mokpo Maritime University | Jang S.-K.,Korean Register of Shipping | Park J.-C.,Korean Register of Shipping
Microscopy and Microanalysis | Year: 2013

In this study, we replaced the expensive blade material with an aluminum-bronze alloy that has excellent corrosion resistance and cavitation characteristics and developed the corrosion protection method to improve durability using an electrochemical method. The objective of this study was to identify the electrochemical corrosion protection conditions to minimize cavitation damage due to generating hydrogen gas (2H2O + 2e - → 2OH- + H2) by means of hydrogen overvoltage before the impact pressure of the cavity is transferred to the surface. In the constant potential experiment under the cavitation environment, the energy was reflected or cancelled out by collision of the cavities with the hydrogen gas generated by the hydrogen overvoltage. As a result, the optimal corrosion prevention potential in the dynamic state is assumed to be the range of-1.4 to-1.7 V, which is the range at which active polarization took place. © 2013 Microscopy Society of America.


Kim M.,Korean Register of Shipping | Kim M.-E.,Korean Register of Shipping
17th Power Systems Computation Conference, PSCC 2011 | Year: 2011

The small-scaled onsite generators such as photovoltaic power, wind power, biomass and fuel cell belong to decarbonization techniques. In general, these generators tend to be connected to utility systems, and they are called distributed generators (DGs) compared with conventional centralized power plants. However, DGs may impact on stabilization of utility systems, which gets utility into trouble. In order to reduce utility's burdens (e.g., investment for facilities reinforcement) and accelerate DG introduction, the advanced operation algorithms under the existing utility systems are urgently needed. This paper presents the advanced voltage regulation method in distribution systems since the sending voltage of voltage regulators has been played a decisive role restricting maximum installable DG capacity (MaxC-DG). For the proposed voltage regulation method, the difference from existing voltage regulation method is explained and the detailed concept is introduced in this paper. MaxC-DG estimation through case studies based on Korean model network verifies the superiority of the proposed method.


Song K.H.,Korean Register of Shipping | Ha T.B.,Korean Register of Shipping
11th International Symposium on Practical Design of Ships and Other Floating Structures, PRADS 2010 | Year: 2010

The ship motions and wave loads based on 3D linear potential theory are very useful to evaluate structural safety of Tanker or Bulk Carrier of which hull shape over mean water line does not vary significantly but keep almost same shape. However, this linear theory is not valid for container ships which have very large bow and stern flare angle in order to carry more containers. The effect of geometrical nonlinearity due to large flare angle gets more and more important for current very large or ultra large container ships because the depth and draft keeps almost same due to limited depth of harbors, while the breadth gets larger and larger. Therefore, 3D Nonlinear Ship motion and Wave Loads are essential to calculate nonlinear dynamic loads for structural safety evaluation of container ships. In this paper, the theoretical background of 3D Nonlinear ship motion and wave loads is introduced and the verification of the code is carried out through model test. Also, the structural evaluation results for 6,500 TEU Container Carrier are shown based on both of 3D linear theory and nonlinear theory and the effect of 3D Nonlinear effect on ship structure are summarized especially in the view of hull girder strength. © 2010 COPPE/UFRJ.


Kim S.-J.,Mokpo Maritime University | Park J.-C.,Korean Register of Shipping | Jang S.-K.,Mokpo Maritime University
Advanced Materials Research | Year: 2013

The Al alloy is environmental friendly, easy to recycle, and provides a high added value to fishing boats. Aluminum alloy do not corrode due to the formation of an anticorrosive passive film, such as, Al2O3 or Al2O3·3H2O which resists corrosion in neutral solution. In seawater, however, Cl- ions destroy this passive film. We investigated on several electrochemical tests undertaken to determine the optimum conditions in seawater for corrosion protection of casted AC7AV aluminum alloy. The components of casted AC7AV aluminum alloy are similar with Al-Mg alloys(5xxx series) which are used for ship. Result of electochemical experiment, the optimum protection potential range with regards to hydrogen embrittlement and stress corrosion cracking was determined to lie between -1.3 and -0.7 V(vs Ag/AgCl). © (2013) Trans Tech Publications, Switzerland.


Han M.S.,Mokpo Maritime University | Park I.-C.,Mokpo Maritime University | Park J.C.,Korean Register of Shipping | Jeong J.-Y.,Mokpo Maritime University | Kim S.-J.,Mokpo Maritime University
Advanced Materials Research | Year: 2013

The sustainable development of engineering, mechanical instrument requires higher speed and higher power. It cause a physical damage is excessive damage for underwater rotating system as cavitations and erosion, but also electrochemical corrosion by chloride ion and flow of current in marine environment. In this study, we assessed electrochemical corrosion characteristics of aluminum-bronze that are the material for the underwater rotating system used in the ocean industry and studied the complex behavior of electrochemical corrosion and cavitation corrosion through the hybrid test that also included cavitation corrosion environment. After the cavitation hybrid tests, surface of specimens are observed to measurement damage degree using 3D optical microscope and compared the average of damage depth by immersion time. The observation of the surface micro-structure suggested that the corrosion took place initially in β phase that has poor corrosion resistance in spite of high hardness. © (2013) Trans Tech Publications, Switzerland.

Loading Korean Register of Shipping collaborators
Loading Korean Register of Shipping collaborators