• Fashion & Textile Research Journal
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• v.8 no.5
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• pp.577-584
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• 2006

The binding of heavy metal ions onto cross-linked chitosan in dilute aqueous solution has been investigated as a function of pH (4.0 and 7.0), agitation period (10-180min) and concentration of various metal cations (5, 10, 50 and 100ppm). In order to obtain adsorbents that are insoluble and stable, and prevent the dissolution loss of chitosan into an acidic aqueous solution, chitosan flakes were cross-linked with epichlorohydrine (ECH) and its adsorption behavior was compared with that of the non cross-linked chitosan. An advantage of ECH is that it does not eliminate the cationic amine functional group of chitosan. In terms of adsorption ratio, the chitosan cross-linked at an ECH was inferior to original chitosan and was found that chitosan has a selectivity much remarkable than the cross-linked chitosan in low concentrated metal solutions. However, no significant decreases in the adsorption ratios were observed between the cross-linked ECH-chitosan and the non cross-linked chitosan concerning the adsorption of $Ni^{2+}$, $Co^{2+}$, $Pb^{2+}$ and $Zn^{2+}$ acidic solution.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.4
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• pp.53-62
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• 2009

Lee[15] examined quantity discount contracts between a manufacturer and a retailer in a stochastic, two-period inventory model where quantity discounts are provided based on the previous order size. During the two periods, the retailer faces stochastic (truncated Poisson distributed) demands and he/she places orders to meet the demands. The manufacturer provides for the retailer a price discount for the second period order if its quantity exceeds the first period order quantity. In this paper we extend the above two-period model to a k-period one (where k < 2) and propose a stochastic nonlinear mixed binary integer program for it. In order to make the program tractable, the nonlinear term involving the sum of truncated Poisson cumulative probability function values over a certain range of demand is approximated by an i-interval piecewise linear function. With the value of i selected and fixed, the piecewise linear function is determined using an evolutionary algorithm where its fitness to the original nonlinear term is maximized. The resulting piecewise linear mixed binary integer program is then transformed to a mixed binary integer linear program. With the k-period model developed, we suggest a solution procedure of receding horizon control style to solve n-period (n < k) order decision problems. We implement Lee's two-period model and the proposed k-period model for the use in receding horizon control style to solve n-period order decision problems, and compare between the two models in terms of the pattern of order quantities and the total profits. Our computational study shows that the proposed model is superior to the two-period model with respect to the total profits, and that order quantities from the proposed model have higher fluctuations over periods.

• Journal of Biosystems Engineering
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• v.23 no.2
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• pp.167-178
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• 1998

An Aero-NFT nutriculture system using microcomputer for cultivation of greenhouse melon was developed and the performance of the system was evaluated through experiments. The system could control temperature, EC and pH of the nutrient solution within the error ranges of $\pm$ 0.2$^{\circ}C$, $\pm$ 0.2 mS/cm, $\pm$ 0.1 pH, respectively. The results of cultivation experiment showed that temperature, EC and pH of the nutrient solution were generally controlled within the setting ranges during cultivation period. The growth results were good until pinching, but the fruit quality of melons was not high except sweetness and shape. To optimize performance of the system, more techlical information for nutriculture of greenhouse melon was needed.

• Journal of Korean Institute of Industrial Engineers
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• v.2 no.1
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• pp.85-92
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• 1976

In this paper, the employment planning model is developed which is a decision-making model for determining the optimum employment level with respect to varying net manpower requirement for each planing period such that total cost in a planning horizon is minimized. It is constructed as a nonlinear programming model and a dynamic programming model on the basis of studies in the areas of production smoothing and manpower scheduling. Costs for a planning period are categorized into regular wage cost, hiring cost, and overtime cost. The first is a linear function. The other two cost functions are of quadratic nature. The planning horizon of this planning model is intermediate range (five years) for which a fair planning accuracy can be guaranteed. The model considers learning period for each job class. It is simple and an optimum solution can be easily obtained by direct search techniques.

• Journal of Korean Institute of Industrial Engineers
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• v.12 no.2
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• pp.77-87
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• 1986

This paper presents a heuristic method for solving the discrete-time ordering problem with quantity discounts and deterministic, time-varying demand. This algorithm utilizes a variation of the incremental cost approach(ICA) to determine a near optimal solution. The ICA is the method which reduces the total cost with reduction of the number of orders by one. In order to reduce the number of orders, if the incremental cost for one of the periods is negative, the demand of the period should be purchased in its immediate preceding period. In order to test the performance of this algorithm, an experiment is conducted that involves a large number of test problems covering a wide variety of situations. The result of the experiment shows that the proposed algorithm has 80.5% better solutions than the adjusted part period algorithm(APPA), which is known to be the best heuristic method.

• Clean Technology
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• v.18 no.4
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• pp.390-397
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• 2012

Removal characteristics of lead-contaminated soil at the military shooting range located in the Changwon city were studied experimentally using soil washing process. As a washing solution, hydrogen chloride (HCl) concentrations of 0.001, 0.01, 0.1 and 0.2 N were used, and soil : solution ratios were 1 : 2, 1 : 3, 1 : 4, and 1 : 5. Particle diameter of contaminated soil of 4-0.075 mm, and washing period of 5, 10, 15, 20, 30, 60, and 120 min were used as operating parameters. The optimum concentration of HCl solution was 0.1 N (56.3% of Pb removal efficiency) with 15 minutes operation period in views of economics, and the optimum soil : solution ratio was determined as 1 g : 3 mL for 69.7% of Pb removal efficiency with 0.1 N HCl and 15 minutes washing period. As washing period increased, removal efficiency was increased until 20 min of the removal efficiency of 75.3%, and then almost stable. Pb removal efficiency in soil particle diameters of 0.075 mm or more was ranged from 77.0% to 82.0%, but it was decreased to 52.8% in diameter of less than 0.075 mm. Therefore, the optimum cut-off size of the soil particle diameter was found less than 0.075 mm. Combined HCl solution and ultrasonic washing method showed better removal efficiency compared to only water or HCl washing method for particle sizes above 0.075 mm.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.3
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• pp.216-221
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• 2004

Treatment effect of benzyladenopurine (BA) used to block the lateral roots formed on soybean sprouts should be influenced by its applying methods. This study was done to check the effects of temperature and period from seed imbibition into 2 ppm BA solution to the first watering for sprout culture on growth and morphology of soybean sprouts. Imbibed three cultivar (cv. Pungsannamulkong, Sowonkong and Junjery) seeds for 5 houys into 2 ppm BA solution were placed under different temperatures (AT; 20, 30, $40^{\circ}$) and periods (AP; 0, 1, 2, 3, 4 hours). On the 6th day, the soybean sprouts were classified by 4 categories on the base of hypocotyl length; ＞7cm, 4 to 7cm), ＜ 4cm and non-germination to calculate their composition rates, number of lateral roots, lengths of hypocotyl and root diameters at middle and hook of hypocotyl, and fraction dry weights were measured. Germination and growth responses of the cultivars were changed by AT and AP treatments. The responses, lateral root formation and fresh weights were, however, mainly affected by the cultivars used rather than Af treatment. Rate of the sprouts which formed lateral roots was decreased with increased periods to 4 hours, but their number per sprout was not different between the treatments of longer than 3 hours. Lengths of hypocotyl and root organ and total fresh weights were the highest in an hour AP treatment although longer than 3 hour AP treatments did not showed the significant difference in the lengths. Conclusionally AP treatment was more important than Af one in seed aeration for soybean sprout culture immediately after imbibition into BA solution, and was done at least for 3 hours.

• Korean Journal of Veterinary Research
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• v.27 no.1
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• pp.27-34
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• 1987

To verify the direct effects of the thyroid hormone ($T_3$) on the rabbit heart, $T_3$-Tyrode solution in vitro was perfused on the normal atrial muscles and enzymatically isolated ventricular myocytes of the rabbit. All the experimental procedures were conducted at $35^{\circ}C$ and the same procedures were repeated after Ca. 120 minutes from the beginning of $T_3$-Tyrode perfusion. Compared to the state between the normal Tyrode solution and $T_3$-Tyrode solution, results were observed on the same cells by electrophysiological methods (conventional intracellular recording and whole cell patch clamping) as soon as possible. The results obtained were as follows : 1. Action potential duration (APD) on the left atrial muscle was reduced under the perfusion of $T_3$-Tyrode. 2. Absolute refractory Period was shortened by $T_3$-Tryrode perfusion. (117 msec./114 msec., 90 msec./78 msec.) 3. Maximal Ca currents ($i_{Ca}$) were decreased in single: ventricular myocytes under the $T_3$-Tyrode (2.98 nA) than under the normal Tyrode (6.65 nA) 4. On I-V relation, reversal potential was shifted to lower membrane potential and membrane potential showing maximal $i_{Ca}$was lowered from +10mV to -20mV by $T_3$ effect. 5. Above results were likely to explain that tachycardia in the hyperthyroid state was caused in part by the reduced repolarization phase and the reduced refractory period due to the decrease of the Ca current.

• Food Science and Preservation
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• v.10 no.3
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• pp.401-405
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• 2003

The antibiotic and antioxidant effect of botanical antimicrobial agent-citrus product(BAAC) prepared from citrus fruits were investigated by using fishmeats made from pollack and ascidian fillet. We inoculated Salmonella typhi into fishmeats that were aferwards treated with BAAC varying the concentration level (50-500ppm) including the control not-treated with BAAC. While specimens were stored at 5$^{\circ}C$ for designated period, we measured changes of total number of bacteria, peroxide level and textural properties. In addition, we performed organoleptic examination, focusing on appearance, texture and odor for fishmeats treated with BAAC and stored for designated period. For pollack and ascidian fishmeats, the initial total number of bacteria were 3.7${\times}$l0$^4$CFU/g and 7.5${\times}$l0$^4$CFU/g, respectively. After they were treated with 250 ppm of BAAC solution and stored for 5 days at 5$^{\circ}C$, the figures reduced to 2.5${\times}$l0CFU/g and 8.4${\times}$10CFU/g. No bacteria were found in fishmeats treated with above 500 ppm of BAAC, which remarkably proved antibiotic effect of BAAC solution. Furthermore, all the BAAC-treated specimens exhibited notable antioxidant effect. Fishmeats which were previously treated with 500 ppm of BAAC solution and stored for 30 days at 5$^{\circ}C$, showed the lower peroxide level of 16.5 meq/kg than 68.9 meq/kg in the control of pollack and 21.2 meq/kg than 80.7 meq/kg in the control of ascidian. In the results of texture and organoleptic evaluation we could also observe good effects of BAAC on maintaining the freshness of fisher products.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.2
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• pp.42-51
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• 2010

Herbs and shrubs are employed for environmental restoration purposes. Among common herbs and shrubs, few species with low germination rates were selected and studied for enhanced germination rates and decreased germination times via soaking treatment. Rhus chinensis, incubator grown samples treated with the bacterial solution for 72hrs followed by immediate seeding showed the highest germination rate of 26.7% and germination period of 5.7 days, 3 days decrease from the control. Treatment of distilled water (t=3.79, p<0.01), nutrient broth (t=4.44, p<0.00) and bacterial solution (t=4.42, p<0.00) showed highly significant difference. In the case of soil tests, treating in the nutrient broth for 72 hrs followed by immediate seeding yielded the the highest germination rate of 23.3% with 7.3 days to initial germination, a decrease of 14.7 days with respect to the control. All the samples followed by immediate seeding showed significant difference (t=2.13, p<0.05). Incubator grown samples of Lespedeza cyrtobotrya showed different results. The incubator samples suspended for 48 hrs in distilled water followed by immediate seeding and 1 day drying displayed the highest germination rate of 96.7%, surpassing that of the control by 33.4%. The incubator samples treated with the distilled water and nutrient broth showed enhanced germination. But only the samples treated with distilled water and nutrient broth for 48hrs showed the increased germination in soil tests. All the sample treated for 24 hrs followed by immediate seeding or dried for 1 day showed initial germination as early as 1 day in incubator. The initial germinations were shortened in the samples treated with distilled water and nutrient broth for 48hrs in soil tests. Lespedeza cuneata incubator sample treated with nutrient broth for 24 hrs and dried for 1 day exhibited the highest germination rate of 83.3%, a 31.1% improvement over the control. The incubator samples treated with distilled water for 48 hrs (t=4.20, p<0.01) showed effective increase of germination. The treatment of distilled water (t=2.96, p<0.05) and bacterial solution (t=2.24, p<0.05) showed significant difference. The germination rates in soil were less than those of incubator and the control. The incubator samples treated with distilled water and bacterial solution displayed 1 day germination period, shortened by 1.3 days compared to the control. For soil grown samples, the samples treated with distilled water showed delayed initial germination and those treated with nutrient broth for 48hrs and bacterial solution for 72hrs shortened initial germination.