• Journal of the Korean Society of Marine Environment & Safety
• /
• v.22 no.7
• /
• pp.900-905
• /
• 2016

The field of power system harmonics has been receiving a great deal of attention recently. This is primarily due to the fact that non-linear (or harmonic-producing) loads comprise an ever-increasing portion of what is handled at a typical industrial plant. The incidence rate of harmonic-related problems is low, but awareness of harmonic issues can still help increase offshore power plant system reliability. On the rare occasion that harmonics become a problem, this is either due to the magnitude of harmonics produced or power system resonance. This harmonic study used an electrical configuration for the offloading scenario of a Floating LNG (FLNG) unit, considering power load. This electrical network configuration is visible in the electrical network load flow study part of the project. This study has been carried out to evaluate the performance of an electric power system, focusing on the harmonic efficiency of an electrically driven motor system to ensure offshore plant safety. In addition, the design part of this study analyzed the electric power system of an FLNG unit to improve the safety of operation and maintenance.

• Journal of Digital Convergence
• /
• v.13 no.3
• /
• pp.65-73
• /
• 2015

The purpose of this study is to examine the relationship between sustainable PLM(Product Lifecycle Management) activity and performance. To ensure this purpose, we designed the S-PLM Framework which is consisted of traditional PLM activity and sustainable PLM activity. We also conducted path analysis to investigate PLM success factor on manufacturing company and to understand the relationship between these success factors. First the result of analysis of the relationship between traditional PLM activity and sustainable performance. Second, there is significantly positive relationship between sustainable activity and performance. Third, traditional PLM activity and sustainable PLM activity factor have an influence on the innovation performance factor. Fourth, sustainable performance have an effect on the management and business performance. In conclude we analyzed and verified the influence sustainable PLM establishment mechanism and the sustainable PLM activity factors. Therefore this study is to create innovative performance and to improve efficiency of Convergence PLM establishment and operation.

• Journal of Digital Convergence
• /
• v.14 no.8
• /
• pp.37-46
• /
• 2016

Patent application as achievements from R&D institutions in public sector have quantitatively increased by expanding R&D investment for enhancing competitiveness but there have been few tangible outputs from the investment. From this reason, TLO(Technology Transfer&Licensing Organization) and its operation becomes more important to implement technology transfer and commercialization and to bring success in the related business. To get work done more efficiently and to improve utilizing products of the R&D in the TLO, this research is to draw domains and activities of TLO and establish its task systems by prioritizing activities. From literature reviews and expert interviews, we generated 6 work domains and 21 task items. Applying AHP analysis, we discriminated the relative importance from task items and analyzed its priority. The finding of this research can provide implications for TLO to increase work efficiency and improve its performance.

• Clean Technology
• /
• v.24 no.2
• /
• pp.87-98
• /
• 2018

Phosphorus (P) is an essential and irreplaceable element for all living organisms, and it is widely used as a fertilizer. Unfortunately, it is estimated that phosphate reservoir is depleted within about 100 years. Sewage sludge ash (SSA) is an alternative resource for P recovery because of its high P content. However, SSA cannot be directly used as a fertilizer due to heavy metals in it and low P bioavailability. Thermochemical treatment with Cl donor is known to reduce heavy metal contents and increase P bioavailability of SSA. Literature review on thermochemical technologies of SSA for the reduction of heavy metals and bioavailability enhancement has been carried out to estimate the status of current P recovery technology and to develop strategic future research plan for P recovery. The review showed that $CaCl_2$ and $MgCl_2$ were the most effective Cl donors and reaction temperature (< $1000^{\circ}C$) was the critical operation condition for the reduction. The removal efficiency depends on the species of heavy metals. Thermochemical technology of SSA for P recovery showed the possibility of commercial application in the near future to overcome the coming crisis of human sustainability by P depletion, but it needs cost effectiveness and more ecofriendly process to reduce energy consumption.

• Clean Technology
• /
• v.26 no.2
• /
• pp.96-101
• /
• 2020

In this paper, the commercial feasibility of trigeneration, producing heat, power, and hydrogen (CHHP) and using biogas derived from macroalgae (i.e., seaweed biomass feedstock), are investigated. For this purpose, a commercial scale trigeneration process, consisting of three MW solid oxide fuel cells (SOFCs), gas turbine, and organic Rankine cycle, is designed conceptually and simulated using Aspen plus, a commercial process simulator. To produce hydrogen, a solid oxide fuel cell system is re-designed by the removal of after-burner and the addition of a water-gas shift reactor. The cost of each unit operation equipment in the process is estimated through the calculated heat and mass balances from simulation, with the techno-economic analysis following through. The designed CHHP process produces 2.3 MW of net power and 50 kg hr^-1 of hydrogen with an efficiency of 37% using 2 ton hr^-1 of biogas from 3.47 ton hr^-1 (dry basis) of brown algae as feedstock. Based on these results, a realistic scenario is evaluated economically and the breakeven electricity selling price (BESP) is calculated. The calculated BESP is ¢10.45 kWh^-1, which is comparable to or better than the conventional power generation. This means that the CHHP process based on SOFC can be a viable alternative when the technical targets on SOFC are reached.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.21 no.6
• /
• pp.543-553
• /
• 2008

Shipbuilding is a kind of ETO(Engineering To Order) industry which designs and produces a product in accordance to various requirement of customers, rules and regulations. Recently, the number of ordered ships has been increased by up to two or three times in each domestic shipyards. Most shipyards have been adopted 3D ship CAD, ERP(Enterprise Resource Planning) and APS(Advanced Planning System) to get an efficient product development and manufacturing system. However, not only the effective operation of 3D ship CAD, ERP and APS but also the production efficiency can be achieved only if product information management which can manages the product data is implemented in an integrated environment. Present study has suggested a systematic approach to implement a PLM system to manage the product data in early design shipbuilding. Also, a prototype of PLM is implemented to manage the product data in a basic ship-design. In the prototype system, a product structure and architecture of PLM is considered.

• Plant Journal
• /
• v.12 no.1
• /
• pp.29-36
• /
• 2016

It is becoming increasingly important to make use of alternative energy source. because It is not able to rely on only fossil fuel for the recent increasing demand of energy consumption. With this situation, lots of studies for utilizing low grade energy such as industrial waste heat, solar energy, and geothermal energy have been conducted. The aim of this study is to predict the operation characteristics of working fluid by using performance analysis program (ThermoFlex) through the system analysis which is not mixing district return water but using ORC(Organic Rankine Cycle, hereinafter ORC) as a downstream cycle when accumulating district heating (hereinafter DH). In this study, We conducted the performance analysis for the case which has the district heating water temperature($120^{\circ}C$) and Flow rate of $163m^3/h$ (including District Heating return water flow), and examined several working fluid which is proper to this temperature. The case using R245fa (which is the best-case) showed 269.2kW power output, 6.37% efficiency. Additionally, Cut down on fuel was expected because of the boiler inlet temperature increase by being Formed $57.3{\sim}85^{\circ}C$ in a temperature of district heating return water, depending on a pressure change of a condenser in ORC system.

• Korean Journal of Plant Resources
• /
• v.8 no.3
• /
• pp.297-302
• /
• 1995

The experiment is conducted to reduce the labor and production cost with the labor save of harvest if cultivating the potatoes using the machine and the results are as follows. On labor saving effect in transparent vinyl mulching, digging working hours per 10a in the case of using tractor are 60 min., fixing + turning time is 5 min. and 30sec., the time of harvest is 65 min and 30sec., digging working hours using cultivator are 99 min. and fixing +turning time is 5 min. and 30sec., but the time of hand harvesting is 990 min. and in digging labor saving effect, tractor shows 94% in the harvesting period and harvest by cultivator 90%. On non mulching cases, the harvest by tractor takes 49 min. and 30 sec. and that by cultivator does 87 min. and 30 sec., and digging labor saving effect shows 94% in the tractor harvest and 90% in the cultivator harvest. Therefore, on the operation efficiency per hour, in the case of tractor with digger vinyl mulching and non mulching show, $0.091\sim0.121ha$ and in the case of cultivator with digger both show $0.057\sim0.069ha$, so in the mechanized harvest of potatoes, the harvest by tractor with digger is the best. On the cost and labor save for harvesting the potatoes with labor saving effect, tractor shows 19 hours and 20 min./10a in vinyl mulching and 19 hours. and 54 min./10a in non mulching, so it shows the short hours for harvesting. And labor saving effect shows $42\sim45%$ in comparison with 35 hours and 21 min. $\sim35$ hours and 23 min.($123,113\sim130,613$ won) of the hand harvest, so the cost was reduced to $71,250\sim72,225$ won. On the cultivator with diggers, vinyl mulching takes 19 hours and 55 min. and non mulching 19 hours and 38 min., so the labor saving effect and cost were reduced to $14\sim44%$ ($72,675\sim73,313$ won) in comparison with the hand harvest.

• Korean Journal of Medicinal Crop Science
• /
• v.5 no.4
• /
• pp.284-288
• /
• 1997

In order to study on suitable harvest time of adlay utilizing self-feeding combine harvester with four rows, which is originally designed for rice harvest, harvesting were carried out at four different times (40, 50, 60 and 70 days after anthesis) . For efficient operation, appropriate working rows were 2 rows at 50 days after anthesis and working speed was 0.26m/sec at 60 days after anthesis. Theoretical working capability was 11.23a/hr at 60 days after anthesis. As the harvesting was delayed, water content of adlay decreased. Water content of culm+leaf was $69.7{\sim}55.3%$ and water content of grain was 34.2% at 60 days after anthesis. The later adlay was harvested. the higher the percent of ripened grain was. But the immature grain was decreased. Remnants was less than 1.8% at 60 days after anthesis. The later adlay was harvested, the heavier volume weight was. Yield was the highest at 60 days after anthesis. When utilizing self-feeding combine harvester with four rows, which was originally designed for rice harvest, suitable harvesting time was 60 days after anthesis. Therefore, theoretically suitable harvest time was 68 days after anthesis.

• Membrane Journal
• /
• v.22 no.3
• /
• pp.171-177
• /
• 2012

Effect of humic acid (HA), photo-oxidation and adsorption with periodic $N_2$ back-flushing was investigated in hybrid process of ceramic ultrafiltration and photocatalyst for drinking water treatment. It was compared and investigated with the previous result at water back-flushing in viewpoints of membrane fouling resistance ($R_f$), permeate flux (J), and total permeate volume ($V_T$). As decreasing HA, $R_f$ decreased dramatically and J increased, and finally $V_T$ was the highest at HA 2 mg/L. As HA concentration increased from 2 to 10 mg/L, the membrane fouling resistance after 180 mins' operation ($R_{f,180}$) improved 0.8 times more than that of water back-flushing. Therefore, HA concentration should affect on the membrane fouling at $N_2$ back-flushing than water back-flushing. Turbidity treatment efficiencies were almost constant independent of HA concentration, but HA treatment efficiency was the maximum at HA 2 mg/L. This means that adsorption and photo-oxidation of photocatalyst beads could removed HA at HA 2 mg/L, but it was not enough at 4 mg/L. Beyond HA 6 mg/L, UF could effectively treat HA by thick cake layer on membrane surface and severe inner membrane fouling.