• Journal of the Society of Naval Architects of Korea
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• v.41 no.1
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• pp.64-69
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• 2004

In recent years, Medium size high speed Ro-Pax vessel has appeared at European sea and especially Agean sea is a center of operating in this type of Ro-Pax. This vessel operates its high Froude number range and requires higher engine power due to considerably increased resistance in comparing to large Ro-Pax in high speed range. SHI has investigated this kind of high speed Ro-Pax in accordance with market requirements and developed more advanced vessel to meet the future market needs. Process of hull form development, model test results and design of general arrangement results are introduced in this paper.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.70-75
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• 2001

Intensive experimental investigations were carried out to provide information of the effects of inflow on the rolling characteristics and stability of ships, which becomes great concern in relation to ship's capsizing. A series of systematic experiments have been performed considering the effects cf combined motion of roll-heave-sway and relevant parameters, such as roll angle and period, tank water height etc. To accommodate this type of experiments with 3-degree of freedom of motion, a bench tester has been developed and verified using existing data. Also, theoretical application of anti-roll tank has been incorporated to support the process of investigation. A model of Ro-Ro ships is used in the present study as this type of vessels, as well as fishing vessels, with large open decks, can loose stability rapidly when there is inflow on the decks.

• Nuclear Engineering and Technology
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• v.31 no.5
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• pp.506-511
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• 1999

The pilot system for radioactive liquid laundry waste was developed with treatment capacity, 1ton/hr and set up in the Yong Kwang unit #4. The system is composed of tank module, RO systems and a UV/$H_2O$$_2$photo-oxidation unit. The RO system consists of the BW unit (low-pressure RO for brackish water desalination) and the SW unit (high-pressure RO for seawater desalination). The BW unit possesses 4 RO membranes and it can reduce the feed water volume down to 1/10. This concentrated feed water can be reduced again up to 1/10 in its volume in the SW unit composed of 4 RO membranes. The UV/$H_2O$$_2$ photo-oxidation process unit was used for the detergent degradation. The operation of the pilot system was carried out and verified in its capability through the continuous operation and concentration operation using the actual liquid waste from the power plant. The design criteria and data for industrialization were yielded. The efficiency of the UV/$H_2O$$_2$ photo-oxidation process and the optimum operational procedure were evaluated. The decontamination factors for radioactive cobalt and cesium were measured. This on-site test showed the experimental result in the DF$\geq$300 and volume reduction factor$\geq$100.

• Membrane and Water Treatment
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• v.5 no.3
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• pp.221-233
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• 2014

Simulations were conducted to predict supersaturation along Reverse Osmosis (RO) modules for seawater desalination. The modeling approach is based on the use of conservation principles and chemical equilibria equations along RO modules. Full Pitzer ion interactive forces model for concentrated solutions was implement to calculate activity coefficients. An average rejection rate for all ionic species was considered. Supersaturation has been used to assess scaling. Supersaturations with respect to all calcium carbonate forms and calcium sulfate were calculated up to 50% recovery rate in seawater RO desalination. The results for four different seawater qualities are shown. The predictions were in a good agreement with the experimental results.

• Membrane Journal
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• v.22 no.4
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• pp.235-242
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• 2012

Ammonium perchlorate (AP) is primarily derived from the process of liquid incineration treatment when dismantling a solid rocket propellant. A series of batch dead-end nanofiltration (NF) and reverse osmosis (RO) membrane experiments were conducted to explore the retention mechanisms of AP under various hydrodynamic and solution conditions. Low levels of silicate type of siloxane had been detected through the GC/MS and FTIR analysis of liquid solutions extracted from solid ammonium perchlorate composite propellant (APCP). It is indicated that NF/RO membranes fouling in the presence of APCP was mainly attributed to the AP interactions because the concentration of silicate type of siloxane was negligible compared to that of AP. The osmotic pressure of AP was presumably resulted in the flux declines ranging from 13 to 17% in the case of the application of low-pressure (551 and 896 kPa for NF and RO) compared to those in application of high-pressure. The retention of AP by NF/RO membranes significantly varied from approximately 10 to 70% for NF and 26 to 87% for RO, depending on the operating and solution water chemistry conditions. The results suggested that retention efficiency of AP was fairly increased by reducing concentration polarization (i.e. application of low-pressure and stirring speed of 600 rpm) and increasing the pH of a solution. The result of this study was also consistent with the previous modeling of 'solute mass transfer of NF/RO membranes' and demonstrated that hydrodynamic and solution water chemistry conditions are to be a key factor in the retention of AP by NF/RO membranes.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.4
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• pp.391-396
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• 2014

Ultrapure water (UPW) is water containing nothing but water molecule ($H_2O$). The use of UPW is increasing in many industries such as the thermal and nuclear power plants, petrochemical plants, and semiconductor manufacturers. In order to produce UPW, several unit processes such as ion exchange, reverse osmosis (RO), ultraviolet (UV) oxidation should be efficiently arranged. In particular, RO process should remove not only ions but also low molecular weight (LMW) organic matters in UPW production system. But, the LMW organic matter removal data of RO membranes provided by manufacturers does not seem to be reasonable because they tested the removal in high concentration conditions like 1,000 ppm of isopropyl alcohol (IPA, MW=60.1). In this study, bench-scale experiments were carried out using 4-inches RO modules. IPA was used as a model LMW organic matter with low concentration conditions less than 1 ppm as total organic carbon (TOC). As a result, the IPA removal data by manufacturers turned out to be trustable because the effect of feed concentration on the IPA removal was negligble while the IPA removal efficiency became higher at higher permeate flux.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.4
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• pp.489-495
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• 2011

Silt Density Index (SDI) has been used as a fouling index for reverse osmosis (RO) processes for decades. In order to decrease RO fouling, feed water should meet SDI standard, which was used to select a proper pretreatment system for RO processes. However, SDI is supposed to be sensitive only to particles larger than 0.45 ${\mu}m$ in terms of diameters while nanoparticles and dissolved organic matter can be potent foulants for RO processes. Our study started from the suspected performance of SDI as a RO fouling index. SDI data from pilot plants located world wide including South Korea were collected and analyzed. Suspended partcle concentration (i.e., turbidity and particle counts), and dissolved organic matter concentration (i.e., dissolved orgnaic carbon (DOC) concentration) data were also collected and compared to SDI values of same water samples. We found that SDI values were not only affected by suspended particle concentration but also by dissolved organic matter concentration. Therefore SDI can be used as a reasonable fouling index for RO feed water because the main foulants for RO processes are suspended particle and dissolved organic matter.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.52-71
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• 2018

RO membranes, the core elements for RO process formed using polyamide, have found prominent space in membrane technology. RO membranes with better application perspective could be achieved by precise controlling the kinetics of IP reaction and surface modification strategy. Despite huge progresses, great challenges still exist in trade-off between flux, rejections and fouling. More works are necessary to enhance the performance and stability of RO membranes via surface modification. Further insights into the use of natural monomers are necessary. It is anticipated that this article can provide clues for further in-depth evaluation and research in exploring more advanced RO membranes.

• Membrane Journal
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• v.1 no.1
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• pp.78-95
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• 1991

Water factory 21(WF 2) in Orange County California, is a advanced wastewater treatment(AWT) plant designed to reclaim biologically treated munidpal wastewater for injection into a seawater barrier system. Processes included are lime treatment air stripping, filtration, activated carbon adsorption, reverse osmosis(RO), and chlorination. The effectiveness of each treatment process is presented including pretreatment, RO dimineralization. The data collected show that the processes, including RO, used at WF-21 are capable of producing a very high quality water on a reliable basis. Treatment reduced all contaminants, to levels below national primary drinldng water regulation maximum contaminant levels. It was found that lime clarified secondary effluent can be used as feedwater to a RO dimineralizer. Experiments with new low pressure membrane(250psi) show great potential for reducing RO cost.

• Membrane Journal
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• v.24 no.5
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• pp.350-357
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• 2014

Pressurized MF membranes are used to remove suspended solid and colloidal materials of wastewater treatment plant effluent as the pretreatment of RO in reuse water production process. Membrane operation data and pollutants removal efficiency are investigated using 100 t/d scale pilot plant in J wastewater treatment plant located in Namyangju city. 40 LMH flux of pressurized MF membrane are obtained in various turbidity and temperature condition. Coagulation of dissolved organic enables flux improvement of MF from 40 LMH to 60 LMH. Pressure drop of 1st RO elements rapidly increased after long-term pause, which is because the complex contamination of organic matter and ionic substances of pluming systems.