• Fibers and Polymers
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• v.7 no.4
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• pp.404-413
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• 2006

This study examines multiple quality optimization of the injection molding for Polyether Ether Ketone (PEEK). It also looks into the dimensional deviation and strength of screws that are reduced and improved for the molding quality, respectively. This study applies the Taguchi method to cut down on the number of experiments and combines grey relational analysis to determine the optimal processing parameters for multiple quality characteristics. The quality characteristics of this experiment are the screws' outer diameter, tensile strength and twisting strength. First, one should determine the processing parameters that may affect the injection molding with the $L_{18}(2^1{\times}3^7)$ orthogonal, including mold temperature, pre-plasticity amount, injection pressure, injection speed, screw speed, packing pressure, packing time and cooling time. Then, the grey relational analysis, whose response table and response graph indicate the optimum processing parameters for multiple quality characteristics, is applied to resolve this drawback. The Taguchi method only takes a single quality characteristic into consideration. Finally, a processing parameter prediction system is established by using the back-propagation neural network. The percentage errors all fall within 2%, between the predicted values and the target values. This reveals that the prediction system established in this study produces excellent results.

• Journal of Korean Society on Water Environment
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• v.20 no.2
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• pp.104-109
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• 2004

Removal of nutrients from domestic sewage or industrial wastewater is needed to protect surface waters from eutrophication. This research was carried out to remove the nitrogen (N) and phosphorus (P) from the wastewater using the iron oxide obtained from the steel industry and the natural zeolite, respectively. This research was conducted in both batch and continuous systems. The removal efficiency of the nutrients was evaluated in the batch system using the varying concentrations of zeolite and iron oxide added. The removal efficiency of N was 60% at the 8g of zeolite added. In the same condition, the removal efficiencies of N were 76% and 82% at 12g and 16g of zeolite added, respectively. Removal efficiency of P was 80% as 8g of iron oxide was added. The removal efficiency of P was correspondingly increased as the concentration of iron oxide was increased. Continuous column system was also used to evaluate the removal efficiency of N and P by the addition of zeolite and ferric oxide, respectively. Removal efficiencies of N were compared in the mixed packing, two stage, and four stage columns, respectively. The removal efficiencies (80%) of N in the separate packed columns (two and four stages) were higher than the mixed packing column (400%) after 90 hr. Whereas, the removal efficiencies of P were similar to each other in the three columns.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.52-63
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• 2009

The problem of scheduling simply periodic task systems upon a uniform multiprocessor is considered. Partitioning of periodic task systems requires solving the bin-packing problem, which is known to be intractable (NP-hard in the strong sense). This paper presents a global scheduling algorithm which transforms a given simply periodic task system into another using a "task-splitting" technique. Each transformed simply periodic task system is guaranteed to be successfully scheduled upon any uniform multiprocessor using a partitioned scheduling algorithm. It is proven that the proposed algorithm achieves the theoretical maximum utilization bound upon any uniform multiprocessor platform.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.2
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• pp.244-252
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• 1999

Intensive selection for muscle development and against fat deposition in pigs during the last 50 years has contributed to the increased incidence of porcine stress syndrome (PSS) and pale soft exudative pork (PSE). Genetics, nutrition and management, preslaughter animal handling, stunning, dehairing and carcass chilling influence the incidence and magnitude of the PSE condition. The normal incidence of PSE has been reported to range from 10 to 30%, but in some isolated instances is up to 60%. The elimination of halothane-positive pigs in breeding programs has reduced PSS and PSE. Further improvements in meat quality by terminal sire evaluation and selection can be achieved within halothane-negative populations because around 20% of the variation in meat color and water binding capacity seems to be genetically related. Pre-slaughter handling on the farm, during transit to the packing plant and at the packing plant can greatly influence the meat quality, contributing 10 to 25% of the variation. An effective stunning method, skinning instead of scalding/dehairing and rapid post-slaughter chilling further reduce the incidence of PSE pork. In addition to proper care and handling a carcass-merit based marketing system, that reflected the value differential between desirable and undesirable meat quality in the pricing system for pigs, would provide a great incentive to change pork production systems in order to improve meat quality, thus improving the image and usefulness of pork as food.

• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.451-457
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• 2007

Four parallel $A^2/O$ systems maintaining an MLSS of 3,000 mg/L were operated to investigate the effects of varying an HRT of anoxic reactors and packing Bio contact media (BCM, fixed beds) in aerobic reactors on organic matter removal and nitrification/denitrification efficiencies. All systems were operated under conditions that the external recycle ratio was kept 0.5 Q while the internal recycle ratio was changed 1.0 Q to 1.5 Q with that $NH_4-N$ concentration of feed was increased to 40 mg/L by adding $NH_4Cl$. In terms of TSS and TCODcr removal efficiency, both systems with BCM and a system without BCM, respectively, had a similar level of the removal efficiency under varied HRTs of anoxic reactors (0.6 hr, 1.3 hr, 2 hr, 2 hr; control, without BC M) showing that varying an HRT of anoxic reactors did not affect the removal efficiency. While SCODcr removal efficiency of systems with BCM was improved approximately 4~5% at the same HRT of anoxic reactor, the removal efficiency of system with BCM was slightly decreased by reducing an HRT of anoxic reactor. The nitrification efficiency for both systems with BCM and a system without BCM was above 94% showing that packing BCM in aerobic reactors and varying an HRT of anoxic reactors did not affect the efficiency significantly despite of increasing $NH_4-N$ concentration of feed. The denitrification efficiency increased from 81.4% to 85.4% at system with BCM while the efficiency decreased when a shorter HRT of anoxic reactors was kept. The excellent effluent quality for $NO_3-N$ concentration was observed although the $NO_3-N$ concentration increased in anoxic reactors that $NH_4-N$ concentration of feed sufficiently converted into nitrate through nitrification. As a result, packing 20% BCM to an aerobic reactor with HRT of 1.3 hr of anoxic reactor in $A^2/O$ system can achieve a similar level of nitrogen removal efficiency in $A^2/O$ system which the aerobic reactor had no BCM and HRT of 2 hr for anoxic reactor is maintained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.272-272
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• 2010

We have fabricated alumina thick films by inkjet printing technology. Two different types of ink system were formulated in order to understand their evaporation behaviors and their evaporation effects on the powder distribution on, the surface during inkjet-printed alumina thick films. Single solvent system was formulated with N,N-dimethylformamide(DMF), which led to coffee ring effects which non-uniformly distributed alumina particles on the substrate during the ink evaporation. However, Co-solvent system which consists of both Water and DMF produced relatively uniform distribution of the particles on the substrate. We believe that these two different distributions of alumina particles are attributed to the ink fluid flow directions in the ink droplets ejected from the different ceramic ink system. We have modulated inkjet parameters such as dot-to-dot distance, line-to-line distance, jetting velocity and jetting drop size in order to find out the optimum condition for the printing of alumina thick films from two different ink systems. The surface roughness, microstructures and dielectric properties of these inkjet-printed alumina thick films were investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.171-171
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• 2009

We have investigated the impact of coffee ring effect on the inkjet-printed $Al_2O_3$ thick films. In a single solvent system such as Dimethylformamide, the coffee-ring-pattern has appeared on the edge of sessile drop after evaporation. The peak-to-valley height difference in $Al_2O_3$ coffee ring is over 2um. This non-uniform deposition of $Al_2O_3$ over the surface leads to sever surface roughness of the inkjet-printed films. However, we have manipulated our printing parameters to improve the surface roughness and the packing density of the printed $Al_2O_3$ films. Our inkjet-printed $Al_2O_3$ films show 10 times smoother surface than the initially printed sample's surface. Also the packing density of the printed Ah03 film becomes 70% of high packed $Al_2O_3$. In this presentation, we would like to present the key process parameters of the inkjet printing process to overcome the genetic coffee ring problem.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.332-332
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• 2010

We have successfully demonstrated the inkjet printing method to create $Al_2O_3$ films withouWe have successfully demonstrated the inkjet printing method to create $Al_2O_3$ films without a high temperature sintering process. In order to remove the coffee ring effect in the ink drop, we have introduced a co-solvent system in order to create Marangoni flow in the ink drop, which leads to the dense packing of ceramic powders on the substrate during inkjet process. The packing density of the Inkjet-printed $Al_2O_3$ films is around 60% (max. 70%) which is very high compared to the value obtained from the same material films by other conventional methods such as film casting, dip coating process, etc. The voids inside the films (which are around 40% of the entire film volume) are filled with the polymer resin (Cyanate ester) by the infiltration process. This resin infiltration is also implemented by the inkjet printing process right after the Ah03 film ink-jetting process. The microstructures of the printed $Al_2O_3$ films are investigated by Scanning Electron Microscope (SEM) to understand the degree of packing density in the printed films. The inkjet-printed $Al_2O_3$ films have been characterized to investigate its thickness and roughness. Quality factor of the printed $Al_2O_3$ film is also measured to be over 300 at 1MHz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1045-1053
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• 2012

Link-16 is a widely used TDL (Tactical Data Link) which uses TDMA (Time Division Multiple Access). Link-16 is a very low rate system, so it supports small size of data like tactical message and voice. However, there are related works to transmit situation awareness information like image due to the increasing interest about EBO(Effect-Based Operation), recently. Special TDMA scheduling is needed not static TDMA of Link-16 for image transmission because image data has much larger size than the existing tactical data. In this paper, we proposed Link-16K which enhances the Link-16 MAC. The proposed Link-16K is compatible with Link-16, and includes dynamic TDMA, new packing method, and an efficient retransmission scheme for image transmission effectively. We can see that image transmission delay is reduced and channel utilization is increased through simulation results of proposed idea.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.1
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• pp.26-33
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• 2020

The plastic waste problem is deepening all over the world. Plastic wastes have serious impacts on our lives as well as environ- mental pollution. The production and use of plastics increases every year, but once they are produced, they usually roam the earth for hundreds or thousands of years to pollute the environment. Although there is growing interest in plastic issues around the world and environmental regulations are being tightened, but no clear solution has yet been found. This study suggests Environmental degradation index (EDI). EDI can help raise consumers' attention to plastic wastes. In addition, EDI will contribute to reduce them in the future. As far as we know, this is the first study. We developed EDI for the confectionery packaging. This study defines four factors that may affect the environment of confectionery packaging: greenhouse gas emissions, energy consumption, methane emissions, and packaging space ratio. Then we quantify the value of each element and compute EDI as the sum of the four component values. In order to evaluate the feasibility of EDI proposed in this study, confectionery-packaging materials distributed in Korea were collected and analyzed. First, the types of confectionery are classified into pies, biscuits, and snacks and basic data was collected. Then the values of the four components were calculated using existing research data on the environment. We can use the proposed EDI to determine how much a product packing affects the environment.