• Korean Journal of Microbiology
• /
• v.53 no.2
• /
• pp.83-96
• /
• 2017

A constructed sea stream in Yeongdo, Busan, Republic of Korea is mostly static due to the lifted stream bed and tidal characters, and receives domestic wastewater nearby, causing a consistent odor production and water quality degradation. Bioaugmentation of a microbial consortium was proposed as an effective and economical restoration technology to restore the polluted stream. The microbial consortium activated on site was augmented on a periodic basis (7~10 days) into the most polluted site (Site 2) which was chosen considering the pollution level and tidal movement. Physicochemical parameters of water qualities were monitored including pH, temperature, DO, ORP, SS, COD, T-N, and T-P. COD and microbial community analyses of the sediments were also performed. A significant reduction in SS, COD, T-N, and COD (sediment) at Site 2 occurred showing their removal rates 51%, 58% and 27% and 35%, respectively, in 13 months while T-P increased by 47%. In most of the test sites, population densities of sulfate reducing bacterial (SRB) groups (Desulfobacteraceae_uc_s, Desulfobacterales_uc_s, Desulfuromonadaceae_uc_s, Desulfuromonas_g1_uc, and Desulfobacter postgatei) and Anaerolinaeles was observed to generally decrease after the bioaugmentation while those of Gamma-proteobacteria (NOR5-6B_s and NOR5-6A_s), Bacteroidales_uc_s, and Flavobacteriales_uc_s appeared to generally increase. Aerobic microbial communities (Flavobacteriaceae_uc_s) were dominant in St. 4 that showed the highest level of DO and least level of COD. These microbial communities could be used as an indicator organism to monitor the restoration process. The alpha diversity indices (OTUs, Chao1, and Shannon) of microbial communities generally decreased after the augmentation. Fast uniFrac analysis of all the samples of different sites and dates showed that there was a similarity in the microbial community structures regardless of samples as the augmentation advanced in comparison with before- and early bioaugmentation event, indicating occurrence of changing of the indigenous microbial community structures. It was concluded that the bioaugmentation could improve the polluted water quality and simultaneously change the microbial community structures via their niche changes. This in situ remediation technology will contribute to an eco-friendly and economically cleaning up of polluted streams of brine water and freshwater.

• Journal of Navigation and Port Research
• /
• v.37 no.1
• /
• pp.113-121
• /
• 2013

IMO(International Maritime Organization) is existed the movement for revising ISM Code so that the maintenance history and the trouble information given trading in a ship can be transferred. An empirical analysis was made on the influence that will have upon shipping industry through surveying on the recognition on ISM Code revision in employees of the relevant field and on the expected problems given being amended ISM Code as the above. In conclusion, the positive effect is judged to be more in the aspect of ship safety, which is the aim of ISM Code, rather than the negative effect, which may take place given being revised ISM Code. In other words, the clean market can be formed through this because fairness is maintained on both sides given trading in a ship by which opening the maintenance record and the trouble history is applied equally to a buyer and a seller. Ships can be reduced a loss of time and cost in preventing similar problems and seeking solution that may appear in important equipments, through this maintenance record. Also, based on these materials, it comes to be available for analyzing a risk of ship and preventing and managing a risk, thereby being increased ability of maintenance and repair in a ship, resulting in being judged to likely contributing to ship safety and environmental-pollution prevention.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.25 no.3
• /
• pp.128-137
• /
• 2013

Due to the global warming and air pollution, interest in renewable energies has increased in recent years. In particular, the crisis of the depletion of fossil energy resources in the near future has accelerated the renewable energy technologies. Among the renewable energy resources, oceans covering almost three-fourths of earth's surface have an enormous amount of energy. For this reason, various approaches have been made to harness the tremendous energy potential. In order to achieve two purposes: to improve harbor water quality and to use wave energy, this study proposed a sea water exchange structure applying an Oscillating Water Column (OWC) wave generation system that utilizes the air flow velocity induced by the vertical motion of water column in the air chamber as a driving force of turbine. In particular, the airflow velocity in the air chamber was estimated from the time variations of water surface profile computed by using 3D-NIT model based on the 3-dimensional irregular numerical wave tank. The relationship of the frequency spectrums between the computed airflow velocities and the incident waves was analyzed. This study also discussed the characteristics of frequency spectrums in the air chamber according to the presence of the structure, wave deformations by the structure, and the power of the water and air flows were also investigated. It is found that the phase difference exists in the time series data of water level fluctuations and air flow in the air chamber and the air flow power is superior to the fluid flow power.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.16 no.4
• /
• pp.393-399
• /
• 2010

Recently, a vessel's maneuvering performance is considered to be an important subject as marine pollution from the ships that stranded on a rock becomes more severe. So, IMO(International maritime organization) has adopted Resolution MSC.l37 to enhance international standards of ship's maneuverability. There's more than one way to improve ship's maneuverability. This research focused on improving ship's maneuverability by high-lift rudder. To predict the maneuverability, the numerical simulation model was used. The evaluation of maneuverability was carried out by turning test and zig-zag test. The results obtained with these simulation showed that the high-lift rudder would be effective in improving the turning ability of the ship. But it was clarified that there Has a possibility that course changing ability night become bad through an increase of rudder lift.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.11 no.2 s.23
• /
• pp.41-49
• /
• 2005

In general, the criminal responsibility of seaman should always be directly assumed by the seamen, according to the principle of self-incrimination. Therefore, the only possible countermeasures for the criminal responsibility of seamen may be to reduce the responsibility by using criminal procedures (ex. the warrant substance examination system, the review system of legality for confinement as much as possible. Another possibility is to reduce the penalty through the revision of the law. In detail, concerning the problem of fine, the maximum fine for oil spill accidents by criminal negligence is KRW 30,000,000 under the current Ocean Pollution Prevention Act, and when an oil spill occurs, the maximum fine tends to be levied regardless of the amount of the spilled oil; thus, it is judged that grading the fine according to the amount of spilled oil may be worth considering. Regarding P & I's payment of fine, contrary to general belief, it is only possible to make up the loss when P & I takes up the legal responsibility or acknowledges its payment. In order to solve the problem, it is possible to consider the option of introducing new collective insurance program or mutual aid system. Also, as seamen are not specialists in legal issues, the ship owners' association or the marine afficers' association need to develop some program through which they can receive systematic assistance from legal specialists including lawyers when they encounter any legal problems (ex. free legal aid programs for farmers and fishermen). Finally, it may be possible to establish enact new laws or revise the existing Act on Special cases Concerning the Settlement of Traffic Accidents to insert a new section on marine accidents.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.24 no.6
• /
• pp.694-700
• /
• 2018

Korea has disposed of medium and low level radioactive waste generated by operating nuclear power plants permanently through the radioactive waste repository located in Gyeongju. However, the maritime transport of radioactive waste is exposed to the risk of marine accidents, and it will be necessary to introduce a system to secure safety from the viewpoint of the function and role of the Korea Coast Guard. Especially, Korea is affected by large-scale marine accidents, such as the Hebei Spirit or Sewol accidents. From this point of view, we analyzed the current status of Korea radioactive waste shipping and examined the response systems of major foreign countries. As a result of examining major cases of accidents, we have operated an Emergency Towing Vessel (ETV) fleet centering on European countries in order to respond urgently to marine casualties that may have social, regional and international effects, such as accidents of similar nuclear material carriers and dangerous cargo ships. It proves a partial effect. Based on this, we propose the introduction of the Korean ETV System. In other words, it is necessary to respond to large-scale marine accidents that could lead to enormous environmental, property, and personal damage, such as marine accidents involving nuclear material ships, large oil tankers, and large passenger ships. For this, it seems necessary to introduce Korea ETV, which can carry out emergency towing, oil pollution control function, large - scale rescue equipment and manpower. This will lead to the enhancement of the Korea Coast Guard response to marine accidents, and will not miss the golden time of the initial response to the national disaster, which will help protect precious people, property and the environment.

• Journal of Navigation and Port Research
• /
• v.26 no.1
• /
• pp.137-145
• /
• 2002

Water flow simulations for environmental problems often require local detailed analyses for better understanding and accurate prediction of the fate of pollutant in water bodies. This study deals with the development and application of a two-dimensional flow an dispersion model to the coastal water area to find out possible changes due to the wide port development plan. As far as the spatial discretization is concerned, the finite element method is attractive because of its flexibility and ability to naturally treat complex coastal geometries. The model uses finite element theory and the Galerkin weighted-residual approach as its basis. Developed model is applied to the Busan New harbor Construction site. Results from the model were compared with the measured water level and flows in four stations. The flow pattern by the model shows to be similar to the observed data away from the construction site where the flow is not affected. From the simulation results, it is concluded that the model may be useful for numerous other studies for planning and management purposes, especially flow and pollution dispersion in the coastal water bodies where the flow is so complicated.

• Journal of the Korea Institute of Building Construction
• /
• v.15 no.2
• /
• pp.143-151
• /
• 2015

Many studies have investigated the airborne chlorides that can weaken the overall durability of the concrete structures due to the corrosion of steel materials, but most of the studies have aimed to examine weathering by exposing various construction materials to the actual oceanic environment. However, with the exposure test, it was difficult to find the threshold of precise corrosive amount of airborne chlorides due to diverse deteriorating environmental factors such as ultraviolet ray, acid rain, floating material from industrial pollution as well as airborne chlorides. Therefore, in this study, an airborne chloride simulator was set up, in oder to conduct a corrosion accelerating test for steels coated by five different finishing materials. As results, it was found that the corrosion began to be observed at $0.58{\sim}0.73mg/dm^2$ for no-coated steel, at $7.89{\sim}8.46mg/dm^2$for urethane-coated steel, at $57.95{\sim}69.48mg/dm^2$ for red lead-coated steel, and at $80.73{\sim}89.35mg/dm^2$ for stainless-coated steel, respectively. Hence, these specific data can be considered as the threshold ranges of corrosion for each coating material for steel.

• Journal of Navigation and Port Research
• /
• v.44 no.3
• /
• pp.195-202
• /
• 2020

The production of larger of ships is a survival strategy for global shipping companies to pursue the economics of scale. According to this strategy, to respond to this situation, many containers are loading/unloading simultaneously in the hub port. Additionally, the container terminals are promoting the introduction of automation to expand the terminal facilities and increase efficiency/productivity of the container yards. European ports have introduced automation to address rising labor costs and shortages of labor. Recently, the construction of fully automated container terminals is increasing in the United States and China to resolve problems such as the slow growth of the global economy, the emergence of large ships, air pollution, and safety accidents. Domestic ports are at an early stage compared to the world's advanced container terminals, and countermeasures are being prepared to respond to the changing ports. However, research on the recognition difference analysis that examines the opinions of stakeholders is insufficient. As a result of analyzing the recognition among the groups, it was found that container terminal operators reduced labor costs, improved shipping services for shipping companies, prevented safety accidents for port union labor, and increased service for port authority and government agencies. Thus, to closely examine the perception among the groups, one-way ANOVA was performed, and then the implications were deduced as the basic data for the smooth introduction of automation.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.6
• /
• pp.739-745
• /
• 2017

Many studies have been conducted to reduce environmental pollution by ships and reduce fuel consumption. As part of this effort, research on power conversion systems through DC distribution systems that link renewable energy with conventional power grids has been pursued as well. The diode rectifiers currently used include many lower harmonics in the input current of the load and distort supply voltage to lower the power quality of the whole system. This distortion of voltage waveforms causes the malfunctions of generators, load devices and inverter pole switching elements, resulting in a large number of switching losses. In this paper, a controller is presented to improve DC output waveforms, the input Power Factor and the THD of an AFE type PWM rectifier used for PLL. DC output voltage waveforms have been improved, and the input Power Factor can now be matched to the unit power factor. In addition, the THD of the input power supply has been proven by simulation to comply with the requirements of IEEE Std514-2014.