Journal of Marine Science and Technology-Taiwan

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    • Research Article15 September 2026

      Reliable Performance Analysis of Polyurea Coatings Used in Offshore Wind Turbines

      Yu-Chang Lin, Yen-Fu Liu, I-Ming Pan, Ming-Yuan Lin, Kang-Yu Liao, Hung-Hua Sheu, Hung-Bin Lee
          This study explores the weather resistance, mechanical properties and corrosion resistance of polyurea coatings in marine environments. The relevant analysis results can be used as a reliability assessment of offshore wind turbine structural coatings during their service life under the influence of marine environments. The long-term experiment uses seawater and 70°C thermal aging conditions as coating reliability assessment items. The microstructure of the samples that have been immersed in seawater for a long time and thermally aged is observed using a scanning electron microscope (SEM). The results show that the surface of the 100 and 125 series polyurea coatings is flat at the beginning of the seawater corrosion test (96 hours). At this time point, the polyurea coating will be accompanied by the phenomenon of mechanical property recovery (i.e., the mechanical properties are improved). When the test time is increased to 168 hours to 3 months, precipitates will appear on the coating surface and holes will form; when the test time is increased to 5-12 months, wrinkles and holes will appear on the test piece. After the functional group detection by Fourier transform infrared spectroscopy (FTIR), the spectrum shows that the peak at a frequency of 3300 cm⁻¹ belongs to the stretching vibration reaction of the N-H bond, and the peak intensity of the N-H bond will weaken as the test time increases. The peak at a frequency of 1660–1620 cm⁻¹ belongs to the carbonyl bond. The test results show that the carbonyl bond peak will shift as the test time increases. This shift belongs to the reaction of hydrogen bond aging and dissociation. Finally, the mechanical property test results show that the mechanical property retention rate of the coating can be maintained at more than 80% after long-term testing. The results of the QUV test and the marine exposure test show that the corrosion rate of the steel pile coating in the marine environment is only 0.00141 mm/year, the weight loss is 0.076%, and there is no significant peeling on the coating surface, only seaweed and shells are attached. The actual results of marine corrosion show that the polyurea coating has excellent corrosion resistance and has long-term stability in harsh marine environments, and can be used as an outer protective layer for marine structures.
    • Research Article15 September 2026

      Corrosion Testing and Simulation of Taiwan Offshore Wind Foundations

      Yao-Hung Fan, Yen-Fu Liu, I-Ming Pan, Chih-Chung Wen, Hsiu-Chen Yeh, Chien-Ming Lo, Tai-Liang Kuo, Hung-Hua Sheu, Hung-Bin Lee
      Taiwan is located in the subtropical zone, with high relative humidity and high salinity in the air, and there are marine organisms attached to structures in the sea. This study will analyze the durability of the corrosion structure materials of the underwater foundation of offshore wind turbines based on the local chemical environment and paint materials. The offshore wind turbine underwater infrastructure is placed in the small boat dock area of the National Taiwan Ocean University in Taiwan. Nine kinds of coatings certified by NORSOK M501 were used to prepare specimens, and the metal exposure test was carried out by hanging in seawater. The hanging positions were respectively in the atmospheric zone, splash zone and submerged zone to complete the analysis of the effect of the water environment and attached marine organisms on the corrosion of the coatings.  The results show that the growth stage of the oyster shells attached to the steel pile will be more mature. The BEASY simulation software was used to analyze the corrosion voltage, and the results of the simulated cathodic corrosion protection of steel piles were consistent with the in-situ measurement results, so the detection standard is reliable.
    • Research Article15 September 2026

      Can Artificial Seagrass Meadows Reduce Pathogenic Bacteria in Coral Reef Ecosystems- A Mesocosm Study

      Hewa Pathirannahelage Athri Thathsarani Weerakoon, Jimmy Kuo, Pi-Jen Liu, Kwee Siong Tew
      Seagrass meadows provide essential coastal ecosystem functions by stabilizing sediments, enhancing water quality, and shaping nutrient and microbial dynamics. With global seagrass losses accelerating due to climate change and anthropogenic pressures, artificial seagrass (ASG) has been proposed as a nature-based alternative to mimic these functions. However, its ability to replicate biological interactions, particularly microbial regulation and pathogen suppression, remains unclear. In this study, we conducted a six-week mesocosm experiment comparing natural Thalassia hemprichii and ASG within coral reef-associated habitats in southern Taiwan. Physicochemical parameters, sedimentation rates, nutrient concentrations, and planktonic and benthic bacterial communities were analyzed. Sedimentation rates and nutrient levels did not show statistically detectable differences between natural and artificial seagrass treatments, suggesting comparable physical conditions under the experimental scale and replication. Community-level analyses showed that within the planktonic communities, ASG and natural seagrass systems differed significantly, whereas benthic communities did not exhibit statistically detectable treatment effects. Nonetheless, taxon-specific patterns revealed important functional divergences. Natural seagrass mesocosms were associated with higher relative abundance of bacterial taxa commonly link to nutrient cycling and nitrogen transformation, including members of the Alphaproteobacteria. In contrast, ASG mesocosms showed higher relative abundances of potentially pathogenic or opportunistic taxa such as Vibrio spp. and filamentous cyanobacteria (Phormidium). Overall, while ASG reproduced key aspects of the physical habitat structure, the microbial community patterns observed here suggest that artificial substrates may not fully capture the biologically mediated interactions characteristic of living seagrass systems. Within the limits of experimental duration and replication, our results indicate that ASG can approximate structural habitat functions but do not provide evidence of full functional equivalence to natural seagrass meadows. ASG may therefore contribute short-term structural habitat complexity, whereas the broader ecological functions associated with intact seagrass ecosystems likely depend on plant-driven biological interactions that were only partially represented under the present experimental conditions
    • Research Article15 September 2026

      Technical Analysis and Market Liquidity in Sale-and-Purchase Transactions of Second-Hand Oil Tankers

      Chih-Chung Cheng, Po-Yin Wang, Heng-Chih Chou
      In addition to using second-hand oil tankers to fulfil immediate shipping needs, shipowners can leverage price fluctuations in the tanker market to make vessel sale-and-purchase (S&P) transactions. Given that the profitability of vessel S&P transactions depends primarily on timing decisions, in this study, technical analysis was applied to identify the optimal transaction timing for 5-, 10-, and 15-year-old second-hand Aframax tankers. In a simulation, an S&P strategy based on technical analysis outperformed a benchmark buy-and-hold strategy, particularly for newer tankers, possibly due to the higher price volatility and lower market efficiency in the markets for these vessels. However, the lack of liquidity in the second-hand tanker market limited the performance of technical analysis in vessel trading, particularly for older tankers. These findings suggest that shipowners can select an appropriate technical indicator to profit from the lack of efficiency in the tanker market while avoiding the pitfalls caused by insufficient market liquidity.
    • Research Article15 September 2026

      A Resilience Early Warning Assessment of the Maritime Supply Chain: A Case Study of China’s New Energy Vehicle Exports

      Xiuqian Chen, Liangyong Chu, Mengyao Wang, Jiayin Du, Yiming Zhang, Xiyao Xu
      Enhancing resilience through early warning is a critical strategy for mitigating disruption risks in the maritime supply chain (MSC). This study proposes a novel early warning assessment framework to determine the resilience of the MSC. It is referred to as a resilience early warning system. An evaluation index system for shipping enterprises is developed based on four dimensions: withstand capacity, adaptive capacity, learning capability, and the external environment. A resilience assessment model that uses the Bayesian best-worst method (BBWM) and the extension cloud model (ECM) is established to quantify MSC resilience. An early warning evaluation model based on a Bayesian network (BN) is constructed to dynamically link resilience indicators with risk propagation patterns. Empirical validation is conducted using the MSC of China’s new energy vehicle (NEV) exports. The proposed BBWM-ECM-BN resilience early warning model uses BNs to capture complex relationships among indicators, overcoming the limitations of traditional methods that rely on linear assumptions. Using probabilistic early warning thresholds instead of deterministic estimates enables risk prediction. The results show the following. (1) The resilience early warning level of China’s NEV export MSC is moderate. Among primary indicators, withstand capacity has a minor warning level, trending toward moderate. Adaptive capacity and External environment are at a moderate level, trending toward severe. Learning capacity is at a moderate level, trending toward minor. (2) Sensitivity analysis shows that Technology Improvement and Innovation Ability is the most influential secondary indicator (0.7360), followed by Security Risk (0.4310) and Government Risk (0.2310). This study advances theoretical understanding of MSC resilience assessment and provides data-driven tools to mitigate escalating international maritime disruption risks, supporting the stable development of China’s NEV export industry and global MSC networks.
    • Research Article15 September 2026

      Spatiotemporal Variations of Tidal Asymmetry Along the Coast of Taiwan: Characteristics and Implications

      Ting-Chieh Lin, Tai-Wen Hsu, Tzu-Chun Huang, Chun-Yuan Lin
      This study presents the first systematic investigation into the spatiotemporal characteristics and evolutionary trends of tidal asymmetry along the coast of Taiwan from 2003 to 2022, employing a moving window method combined with the S_TIDE toolbox.  By quantifying the skewness of the Main Tidal Asymmetry Combinations (MTAC) and their temporal variations, the study reveals significant regional disparities between the eastern and western coasts.  The western coast is primarily dominated by the M2-M4 combination, with the northwestern region exhibiting a flood dominance pattern and the southwestern region characterized by ebb dominance.  Conversely, the eastern coast, attributed to its open topography and minimal tidal wave deformation, is mainly influenced by the O1-K1-M2 combination and displays weaker overall asymmetry.  Notably, the study identifies that specific regions, such as HsinChu and DongShi, are driven by variations in the amplitude of the shallow-water M4 constituent, leading to a significant intensification of tidal asymmetry over time.  Comparative analysis using satellite imagery demonstrates a strong correlation between shoreline evolution (e.g., erosion and accretion) and the observed trends in tidal asymmetry.  These findings elucidate the regional zonation and evolutionary trends of tidal asymmetry in Taiwan, offering a crucial quantitative scientific basis for coastal defense and adaptation strategies

Most Popular Articles

  • Journal Article
    Monitoring of Sandstorms with ROCSAT-1 OCI Data
    15 December 2002Shih-Jen Huang, Gin-Rong Liu, Tsung-Hua Kuo, Tang-Huang Lin, Chih-Kang Liang
    The Ocean Color Imager (OCI) onboard the ROCSAT-1 Satellite was employed to demonstrate its capability in monitoring sandstorm events around Mongolia and northwestern China where they have been occurring in great frequency over these past few years. The OCI measures the radiance from the visible to near infrared regions in six spectral channels. The radiance can be used to calculate the aerosol optical depth (AOD) of the atmosphere through an atmospheric correction algorithm. The variation in the AOD during January and February of 2001 is investigated in this study. A set of OCI images covering the Yellow Sea was selected for analysis. The results showed that the AOD values increased significantly after the sandstorms erupted, where its value was almost four times higher than before.
  • Journal Article
    Impact of Climate Change on Shihmen Reservoir Water Supply
    15 December 2016Tai-Yi Chu, Jyun-Long Lee, Wen-Cheng Huang
    This study evaluated the impact of climate change on the water supply of the Shihmen reservoir in northern Taiwan. Five downscaled general circulation models that represent the daily meteorological data of 2046-2065 were adopted. The future inflow of the Shihmen reservoir was estimated using the tank model. Subsequently, the water supply risk under the given demand and operating conditions was simulated and assessed. Compared with 2004-2011, the average annual precipitation of the Shihmen watershed in 2046-2065 is lower, particularly during the wet season (May-October). Therefore, the risk to the water supply will increase in the first cropping season (from March to June) in the future. To reduce the risk of water shortage caused by public demand, irrigation fallowing during the cropping season is necessary
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    A Note on Grashof’s Theorem
    15 December 2005Wen-Tung Chang, Chen-Chou Lin, Long-Iong Wu
    In this paper, Grashof’s theorem is justified from the perspective of the occurrence of stationary configurations and uncertainty configurations of four-link chains. The link length relations at stationary configurations and uncertainty configurations are examined in detail based on the triangle inequality, and then the conditions for the existence of a crank and a change point are deduced.
  • Journal Article
    Comparison Between ARPA Radar and AIS Characteristics for Vessel Traffic Services
    15 December 2006Bin Lin, Chih-Hao Huang
    Recently most maritime countries in the world have fitted automatic identification system (AIS) in vessel traffic services (VTS) in compliance with regulations of International Convention in order to identify ship name and collect ship information. Traditionally VTS operators use automatic radar plotting aids (ARPA) to get ship maneuvering information for preventing ships from navigational faults. Although the two equipments can provide similar functions for VTS, the operational theory of them is quite different. In this study an experimental observation was carried out by means of ARPA radar and AIS fitted in the building of Merchant Marine Department, NTOU. The detected information was analyzed for comparison of their difference on characteristics. Results reveal that AIS can detect target ships with wider area coverage, larger quantity and more voyage information than ARPA radar. The latter can provide an active monitor to detect small ships that can not be done by AIS. Consequently for navigation safety VTS operators must concentrate on ARPA radar in priority and use AIS as supplementary installation for identification of ships.
  • Journal Article
    Design and Simulation of A C-band Pyramidal Horn Antenna for Water-Level Radar Sensors
    15 April 2015Ke-Ru Chou, Tzong-Dar Wu, Han-Nien Lin, Tai-Shan Liao, Kwong-Kau Tiong
    A prototype C-band pyramidal horn antenna was fabricated after using High Frequency Structure Simulator (HFSS) software to simulate, analyze, and optimize the design parameters. The pyramidal horn antenna was designed to operate as a key detection component for disaster prevention and warning instruments in the domestic development of water-level radar sensor (WLRS). Experimental measurements showed the horn operating with a bandwidth of ~ 800 MHz from 5.4 GHz to 6.2 GHz with the central frequency at 5.8 GHz. The voltage standing wave ratio (VSWR) in the operating frequency range and the radiation pattern gains were measured to be smaller than 1.2 and larger than 16 dB, respectively. The experimental measurements compared well with the simulated results and met the design requirements.
  • Journal Article
    Analysis of Fuel Cell Applied for Submarine Air Independent Propulsion (AIP) System
    15 October 2018Jen-Chieh Lee, Tony Shay
    In this paper, the performance of a 2000-ton hybrid AIP system submarine is investigated by analyzing the weight, volume and efficiency of its propulsion system. The engine of the investigated AIP system employs a low temperature polymer electrolyte membrane fuel cell which makes use of the hydrogen and oxygen as the reactants. More specifically, the reactants of fuel cell in this study are considered from the combination of three fuel storage systems, methanol (MeOH), liquid hydrogen (LH2) and metal hydride (MH2), and two oxidant storage systems, liquid oxygen (LOX) and compressed oxygen (O2). Based on the assumed various daily propulsion load consumptions, a propulsion system of a 3500 kW diesel generator, a 300 kW fuel cell, and a 7500 kWh energy capacity Li-ion battery bank is determined. With the system installed in the submarine, the maximum designed endurance can reach a total of 26 days for the fuel cell using the combination of reactant LH2 + LOX, and the minimum designed endurance can be up to 10 days for using the reactant MH2 + O2. For submarine cruising at zero speed, the submerged endurance of the AIP system using reactant LH2 + LOX plus battery bank is 22.8 times of that using battery bank alone. This value will increase to 25.0 times for submarine cruising at 7.4 knots. At the cruising speed of 5.5 knots, the maximum submerged range of submarine increases a factor of 24.1 for fuel cell using the reactant of LH2 + LOX as compared with operation on battery bank alone. Therefore, the submerged endurance is substantial enhanced for using the combination of fuel cell and battery. In addition, the indiscretion ratio is zero for the AIP system submarine with a cruising speed below 7.1 knots; this can greatly reduce the submarine vulnerability. Based on the weight and volume analysis of the submarine equipped with a hybrid AIP system, the usage of the reactant LH2 + LOX is well suited for a small- to medium-sized 2000-ton submarine with a fuel cell system. Furthermore, using the reactant MeOH + LOX has the advantage for large-sized LT-PEMFC AIP system submarines.

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