• 수산해양기술연구
• /
• 제16권1호
• /
• pp.23-26
• /
• 1980

The pure polypropylen rope has been used for the head rope, and the lead cored polypropylen rope for the ground rope in the anchovy boat seine. These ropes revealed the disadvantage that deforms the net shape due to their elongation. Te improve the disadvantage, authors developed the rope of new construction which is cored by wires and wrapped by polypropylene fibers, 20mm in diameter for the head rope and 40tnm for the ground rope. To compare the physical properties of the improved rope with the conventional ones, some factors are valued and the following results are found. 1. The improved ropes rev~al some disadvantages, such as the head rope is heavier, the ground rope lighter, and both of them are stiffer than the conventional ones, contrary to the required condition of ropes) However no special difficulties are found in practical use. 2. The improved ropes display much advantages, such as elongation is 30 percent less, breaking strength is 35 precent greater, and elastic recovery is 10 percent greater than the conventional ones. Thus, it is considered that the improved ropes are more suitable for the head rope and the ground rope of the anchouy boat seine net than the conventional ones.

• 국제학술발표논문집
• /
• The 9th International Conference on Construction Engineering and Project Management
• /
• pp.929-936
• /
• 2022

In the U.S., the state, local, tribe, and territorial governments seek funding from the federal government through the Public Assistance program to carry out these recovery works. In this paper historic public assistance data between 1998 and 2021 have been analyzed to derive several insights such as: types of disasters causing the most damage, states requiring more support, net present value of the federal expense etc. This paper has found that the states requiring more support from the federal government are not always the states suffering the maximum losses from the disasters. It has also found that the net present value of the federal expense between 1998 and 2020 to restore, repair, reconstruct, or replace disaster damaged roads and bridges across the U.S. is $15 billion in 2021 values. Moreover, this paper has tested the correlation between the states' public assistance funds requirements and the existing condition and performance of roads and bridges as revealed by the American Society of Civil Engineer's infrastructure grade card. It has found a weak correlation between these two. The outcomes of this paper can be used by the decision makers to analyze the viability of any possible alternative to the exiting public assistance program. The insights can also help in better decision making in pre-disaster preparation and post-disaster funds allocation.

• 상하수도학회지
• /
• 제20권1호
• /
• pp.138-146
• /
• 2006

The characteristics of backwash and concentrate discharges depend upon the quality of the water being treated and the net recovery of the membrane system. This paper is to indicate a design methods on the capacities of residuals treatment facilities in membrane processes for drinking water. We operated a demonstration membrane plant with a recovery rate of 90% for designing G-water treatment plant. We investigated on design parameter (optimum coagulant dosage and surface loading rate etc.) to design efficiently the residuals treatment facilities. The settling test was conducted with 1m columns dosing PACl to kaolin and membrane residuals under the experimental condition that discharge permit was under a 60mg/L. When the quantity of membrane residuals was $1,575m^3/day$, the estimated results for 1st thickener demonstrated the surface loading rate of 14.4m/day, detention time of 5.83hr, available depth of 3.5m.

• 설비공학논문집
• /
• 제27권1호
• /
• pp.39-43
• /
• 2015

The Energy and Green House Gas target management system was launched by the Korean Government in 2010. The Korea Emission Trading System will start in 2015. Therefore, simultaneous pursuit of energy saving and greenhouse emission reduction through energy use rationalization is an important obligation of Korean engineers, who import about 97% of domestic energy consumption. Economic analysis of the GHG emission reduction methodologies registered and approved by Korea Voluntary Emission Reduction (KVER) program was conducted. The results for waste heat recovery employed in an energy intensive pulp, paper and wood industry were reported. The emission reduction intensities were 9.7 kg $CO_2$/ton_pulp production. Net Present Value analysis showed that the GHG emission reduction was economically beneficial with an internal rate return of 60%. The results of exergy analysis indicated that the second law efficiencies of waste heat recovery system employed in KVER program were 77.3% and 53.6%. NPV decreased as the exergy decreased.

• Nuclear Engineering and Technology
• /
• 제41권8호
• /
• pp.1101-1108
• /
• 2009

The ocean contains around eighty elements of the periodic table and uranium is also one among them, with a uniform concentration of 3.3 ppb and a relative abundance factor of 23. With a large coastline, India has a large stake in exploiting the 4 billion tonnes of uranium locked in seawater. The development of radiation grafting techniques, which are useful in incorporating the required functional groups, has led to more efficient adsorbent preparations in various geometrical configurations. Separation based on a polymeric adsorbent is becoming an increasingly popular technique for the extraction of trace heavy metals from seawater. Radiation grafting has provided definite advantages over chemical grafting. Studies related to thermally bonded non woven porous polypropylene fiber sheet substrate characterization and parameters to incorporate specific groups such as acrylonitrile (AN) into polymer back bones have been investigated. The grafted polyacrylonitrile chains were chemically modified to convert acrylonitrile group into an amidoxime group, a chelating group responsible for heavy metal uptake from seawater/brine. The present work has been undertaken to concentrate heavy metal ions from lean solutions from constant potential sources only. A scheme was designed and developed for investigation of the recovery of heavy metal ions such as uranium and vanadium from seawater.

• 신재생에너지
• /
• 제6권3호
• /
• pp.22-29
• /
• 2010

The concept of Ocean Thermal Energy Conversion (OTEC) is simple and various types of OTEC have been proposed and tried. However the location of OTEC is limited because OTEC requires $20^{\circ}C$ of temperature difference as a minimum, so most of OTEC plants were constructed and experimented in tropical oceans. To solve this we proposed the modified OTEC which uses condenser discharged thermal energy of existing fossil or nuclear power plants. We call this system CTEC (Condenser Thermal Energy Conversion) as this system directly uses $32^{\circ}C$ partially saturated steam in condenser instead of $20{\sim}25^{\circ}C$ surface sea water as heat source. Increased temperature difference can improve thermal efficiency of Rankine cycle, but CTEC should be located near existing plant condenser and the length of cold water pipe between CTEC and deep cold sea water also increase. So friction loss also increases. Calculated result shows the change of efficiency, pumping power, net power and other parameters of modeled 7.9 MW CTEC at given condition. The calculated efficiency of CTEC is little larger than that of typical OTEC as expected. By proper location and optimization, CTEC could be considered another competitive renewable energy system.

• Nuclear Engineering and Technology
• /
• 제45권1호
• /
• pp.61-66
• /
• 2013

Among the radioactive wastes generated from the nuclear power plant, a radioactive nuclide such as $^{129}I$ is classified as a difficult-to-measure (DTM) nuclide, owing to its low specific activity. Therefore, the establishment of an analytical procedure, including a chemical separation for $^{129}I$ as a representative DTM, becomes essential. In this report, the adsorption and recovery rate were measured by adding $^{125}I$ as a radio-isotopic tracer ($t_{1/2}$ = 60.14 d) to the simulation sample, in order to measure the activity concentration of $^{129}I$ in a pressurized-water reactor primary coolant. The optimum condition for the maximum recovery yield of iodine on the anion exchange resins (AG1 x2, 50-100 mesh, $Cl^-$ form) was found to be at pH 7. In this report, the effect of the boron content in a pressurized-water reactor primary coolant on the separation process of $^{129}I$ was examined, as was the effect of $^3H$ on the measurement of the activity of iodine. As a result, no influence of the boron content and of the simultaneous $^3H$ presence was found with activity concentrations of $^3H$ lower than 50 Bq/mL, and with a boron concentration of less than 2,000 ${\mu}g/mL$.

• Nuclear Engineering and Technology
• /
• 제40권7호
• /
• pp.581-592
• /
• 2008

In this study, a conceptual pyroprocess flowsheet has been devised by combining several dry-type unit processes; its applicability as an alternative fuel cycle technology was analyzed. A key point in the evaluation of its applicability to the fuel cycle was the recovery yield of fissile materials from spent fuels as well as the proliferation resistance of the process. The recovery yields of uranium and transuranic elements (TRU) were obtained from a material balance for every unit process composing the whole pyroprocess. The material balances for several elemental groups of interest such as uranium, TRU, rare earth, gaseous fission products, and heat generating elements were calculated on the basis of the knowledge base that is available from domestic and foreign experimental results or technical information presented in open literature. The calculated result of the material balance revealed that uranium and TRU could be recovered at 98.0% and 97.0%, respectively, from a typical PWR spent fuel. Furthermore, the anticipated TRU product was found to emit a non-negligible level of $\gamma$-ray and a significantly higher level of neutrons compared to that of a typical plutonium product obtained from the PUREX process. The results indicate that the product from this conceptual pyroprocessing should be handled in a shielded cell and that this will contribute favorably to retaining proliferation resistance.

• Nuclear Engineering and Technology
• /
• 제49권3호
• /
• pp.541-548
• /
• 2017

Uranium metal used for fabrication of fuel for research reactors in India is generally produced by magnesio-thermic reduction of $UF_4$. Performance of magnesio-thermic reaction and recovery and quality of uranium largely depends on properties of $UF_4$. As ammonium diuranate (ADU) is first product in powder form in the process flow-sheet, properties of $UF_4$ depend on properties of ADU. ADU is generally produced from uranyl nitrate solution (UNS) for natural uranium metal production and from uranyl fluoride solution (UFS) for low enriched uranium metal production. In present paper, ADU has been produced via both the routes. Variation of uranium recovery and crystal structure and composition of ADU with progress in precipitation reaction has been studied with special attention on first appearance of the precipitate Further, ADU produced by two routes have been calcined to $UO_3$, then reduced to $UO_2$ and hydroflorinated to $UF_4$. Effect of two different process routes of ADU precipitation on the characteristics of ADU, $UO_3$, $UO_2$ and $UF_4$ were studied here.

• 수산경영론집
• /
• 제50권1호
• /
• pp.17-37
• /
• 2019

The purpose of this study is to estimate the resource recovery effect and the economic effect of the fishermen by the fisheries vessel buy-back program. First, this study standardizes the fishing efforts of coastal gill net, coastal trap, and coastal composite fisheries using Gavaris general linear model. Second, the resource evaluation is performed by using vessel buy-back program data, and also the CYP model based on exponential growth function is applied. In order to derive the effect of the vessel buy-back program, the MSY with the vessel buy-back program is compared with the MSY without the vessel buy-back program. Finally, we compare and analyze producer surplus under the equilibrium of the MEY and the OA using bioeconomic model. In conclusion, the vessel buy-back program has shown an increase in resource growth and economic improvement for the remaining fishermen. The result shows that the remaining fishermen are able to obtain an increase in producer surplus of about 53% due to the vessel buy-back program under equilibrium levels of the open access and the maximum economic yield.