• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4A
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• pp.360-370
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• 2010

In this paper, a distributed beamforming problem is considered in an amplify-and-forward (AF) wireless relay network consist of multiple source-destination pairs and relaying nodes. To exploit degree of freedom of the number of beamformers, in the first step, we proposed that the sources transmit their signals through orthogonal channels. During the second step, the relays transmit their received signals multiplied by complex weights to amplify and compensate for phase changes introduced by the backward channels through one common channel. The optimal beamforming vectors are obtained through minimization of the total relay transmit power while the signal-to-interference-plus-noise ratios (SINRs) at the destinations are above certain thresholds to meet a quality of services (QoSs) level. In the numerical example, it is shown that the proposed scheme needs less transmit power for moderate network data rates than other schemes, such as space division multiplexing or time-division multiplexing scheme.

• BMB Reports
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• v.37 no.2
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• pp.199-205
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• 2004

The six lumbrokinase fractions (F1 to F6) with fibrinolytic activities were purified from earthworm Lumbricus rubellus lysates using the procedures of autolysis, ammonium sulfate fractionation, and column chromatography. The proteolytic activities on the casein substrate of the six iso-enzymes ranged from 11.3 to 167.5 unit/mg with the rank activity orders of F2 > F1 > F5 > F6 > F3 > F4. The fibrinolytic activities of the six fractions on the fibrin plates ranged from 20.8 to 207.2 unit/mg with rank orders of F6 > F2 > F5 > F3 > F1 > F4. The molecular weights of each iso-enzyme, as estimated by SDS-PAGE, were 24.6 (F1), 26.8 (F2), 28.2 (F3), 25.4 (F4), 33.1 (F5), and 33.0 kDa (F6), respectively. The plasminogen was activated into plasmin by the enzymes. The optimal temperature of the six iso-enzymes was $50^{\circ}C$, and the optimal pH ranged from pH 4-12. The four iso-enzymes (F1-F4) were completely inhibited by PMSF. The two enzymes (F5 and F6) were completely inhibited by aprotinin, TLCK, TPCK, SBTI, LBTI, and leupeptin. The N-terminal amino acid (aa) sequences of the first 20 to 22 residues of each fraction had high homology. All six isoenzymes had identical aa residues 2-3 and 13-15. The N-terminal 21-22 aa sequences of the F2, F3, and F4 isoenzymes were almost the same. The N-terminal aa sequences of F5 and F6 were identical.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.249-253
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• 2006

We propose a new beamforming algorithm, which is based on simplex downhill optimization method in the presence of pilot channels in cdma2000 reverse-link, for the rake structure antenna array in DS/CDMA communication system. Our approach uses the desired signal(pilot) covariance matrix and the interference covariance matrix. The beamforming weights are made according to maximum SINR criteria using simplex downhill optimization procedure. Our proposed scheme provides lower computational load, better convergence speed, better performance than existingadaptive beamforming algorithm. The simplex downhill method is well suited to finding the optimal or sub-optimal weight vector, since they require only the value of the deterministic function to be optimized. The rake beamformer performances are also evaluated under several set of practical parameter values with regard to spatial channel model. We also compare the performance between conventional rake receiver and the proposed one under same receiving power.

• Korean Journal of Medicinal Crop Science
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• v.26 no.6
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• pp.464-470
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• 2018

Background: Ginseng produced by hydroponics can be cultivated without using agricultural chemicals; thus, it can be used as a raw materials for functional foods, medicines, and cosmetics. This study aimed to determine the optimal harvesting time to obtain the highest levels of ginsenoside and ginseng, as this was not previously unknown. Methods and Results: One-year-old organic ginseng seedlings were transplanted and cultivated using hydroponics for 150 days in a venlo-type greenhouse, using ginseng nursery bed soil and a nutrient solution ($NO_3{^-}-N$; 6.165, P; 3.525, K; 5.625, Ca; 4.365, Mg; 5.085, S; $5.31mEq/{\ell}$). Ginsenoside content and fresh and dry weights were higher at 120 days after transplanting than at 30, 60, 90, and 150 days. Total ginsenoside content was 11.86 times higher in the leaf and stem than in the root at 120 days after transplanting. Ginsenosides F1, F2, F3, and F5 were detected in ginseng leaves and stems. These chemical compounds are known to be effective in altering skin properties, including whitening, anti-inflammation, and anti-aging. Conclusions: Optimal harvesting time for ginseng cultivated using hydroponics was 120 days after transplanting when the biomass and ginsenoside content were highest.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.2_2
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• pp.209-218
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• 2022

The purpose of this study is to analyze an economic assessment of PV-ESS systems based on the power generation performance data of solar power (PV) operating in domestic area, and to calculate the optimal capacity of the energy storage system. In this study, PVs in Gyeonggi-do, Jeollabuk-do, and Gyeongsangbuk-do were targeted, and PVs in this area were assumed to be installed on a general site, and the research was conducted by applying weights based on the facility's capacity. All the analysis was conducted using the actual amount of KPX transactions of PVs in 2019. In order to calculate the optimal capacity of PCS and BESS according to GHI, PV with a minimum/maximum/central value was selected by comparing the solar radiation before the horizontal plane between three years (2017-2019) of the location where PV was installed. As a result of the analysis, in Gyeonggi-do, if the REC weight decreases to 3.4 when there is no change in the cost of installing BESS and PCS, it is more economical to link BESS than PV alone operation of PV. In Jeollabuk-do, it was analyzed that if the REC weight was reduced to 3.6, it was more likely to link BESS than PV operated alone. In Gyeongsangbuk-do, it was analyzed that if the REC weight was reduced to 3.4, it was more likely to link BESS than PV operated alone.

• ALGAE
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• v.39 no.2
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• pp.109-127
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• 2024

High production and efficient harvesting of microalgae containing high omega-3 levels are critical concerns for industrial use. Aeration can elevate production of some microalgae by providing CO₂ and O₂. However, it may lower the production of others by generating shear stress, causing severe cell damage. The mixotrophic dinoflagellate Gymnodinium smaydae is a new, promising microalga for omega-3 fatty acid production owing to its high docosahexaenoic acid content, and determining optimal conditions and methods for high omega-3 fatty acid production and efficient harvest using G. smaydae is crucial for its commercial utilization. Therefore, to determine whether continuous aeration is required, we measured densities of G. smaydae and the dinoflagellate prey Heterocapsa rotundata in a 100-L semi-continuous cultivation system under no aeration and continuous aeration conditions daily for 9 days. Furthermore, to determine the optimal conditions for harvesting through centrifugation, different rotational speeds of the continuous centrifuge and different flow rates of the pump injecting G. smaydae + H. rotundata cells into the centrifuge were tested. Under continuous aeration, G. smaydae production gradually decreased; however, without aeration, the production remained stable. Harvesting efficiency and the dry weights of omega-3 fatty acids of G. smaydae + H. rotundata cells at a rotational speed of 16,000 rpm were significantly higher than those at 2,000-8,000 rpm. However, these parameters did not significantly differ at injection pump flow rates of 1.0-4.0 L min^-1. The results of the present study provide a basis for optimized production and harvest conditions for G. smaydae and other microalgae.

• Korean Journal of Food Science and Technology
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• v.36 no.5
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• pp.733-739
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• 2004

Model for optimally dimensioned PE film bag was developed according to fruit size to maintain best quality of 'Fuyu' persimmon in modified atmosphere packaging (MAP) storage based on relationship between quality and oxygen and carbon dioxide in PE film bag. Harvested persimmons were graded into five sizes, and average weights were LL:261, L:217, M:188, S:168, and SS:154 g. Five fruit units of each grade were optimized in five PE film bag sizes of $150{\times}376,\;140{\times}357,\;130{\times}344,\;130{\times}333,\;and\;120{\times}3l8\;mm$. To minimize quality deterioration such as softening and discoloration, optimal oxygen and carbon dioxide concentrations in PE film bag were 0.5-1.0 and 6.0-8.0%, respectively, and optimal thickness of PE film bag according to fruit size were LL:45, L:50, M:55, S:60, and $SS:65\;{\mu}m$. For all fruit sizes, model for PE film bag area $(mm^2)$ was good quadratic simple equation by fruit weight (g): $Y=-4055.707+627.993X_1-0.701{X_1}^2$. Model far optimal oxygen and carbon dioxide (Y) concentration in PE film bag was suited to linear multiple equation by fruit weight $(X_1,\;g)$ and PE film thickness $(X_2,\;{\mu}m)$. Equations for oxygen and carbon dioxide concentrations (%) were $Y=5.798-0.0109X_l-0.0491X_2\;and\;Y=-2.427+0.01927X_l +0.09646X_2$, respectively.

• Applied Biological Chemistry
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• v.49 no.3
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• pp.215-220
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• 2006

Response surface methodology was implemented to determine an optimal extraction condition in Phellinus linteus water extract. Extraction was performed on 10 experimental conditions including independent variables such as extraction time $(1{\sim}5\;hrs)$ and water volume over sample (sample : $H_2O$ = 1 : $40{\sim}200$, W/V), color browning, reducing and total sugar, that were based on the significant levels of 10% of central composition design. Color browning, reducing and total sugar contents were found to be more affected when the water volume was increased rather than extraction time. Maximum extraction condition was acquired at extraction time of $3.0{\sim}4.5\;hrs$ and water volume of $40{\sim}58.2\;ml$. Being extracted at the optimal extraction condition two of the free sugars, sucrose (0.126%) and glucose (0.012%), were detected. Total content of the free amino acids was found to be $503.26\;{\mu}g%$. Among them, essential amino acid contents were revealed as 5.4%. One major peak from gel permeation chromatography contained polysaccharide(s) with the molecular weights of 10 KDa.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.6
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• pp.355-364
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• 2023

The arbitrary Lagrangian-Eulerian (ALE) method has been extensively researched owing to its capability to accurately predict the propagation of blast shock waves. Although the use of the ALE method for dynamic analysis can produce unreliable results depending on the mesh size of the finite element, few studies have explored the relationship between the mesh size for the air domain and the accuracy of numerical analysis. In this study, we propose a procedure to calculate the optimal mesh size based on the mean squared error between the maximum blast pressure values obtained from numerical simulations and experiments. Furthermore, we analyze the relationship between the weight of explosive material (TNT) and the optimal mesh size of the air domain. The findings from this study can contribute to estimating the optimal mesh size in blast simulations with various explosion weights and promote the development of advanced blast numerical analysis models.

• Journal of Microbiology and Biotechnology
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• v.6 no.4
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• pp.238-244
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• 1996

$\gamma$-Glutamyl transpeptidase ($\gamma$-GTP; EC 2.3.2.2) present in the culture filtrate of Bacillus sp. KUN-17 was purified 400-fold through a consecutive procedure including organic precipitation and column chromatography. The enzyme has an estimated molecular weight of 70, 000 and consists of hetero-subunits with molecular weights of 42, 000 and 22, 000. In vitro optimal conditions for those transfer and hydrolysis reactions appeared to be pH 7.0 at $50^{\circ}C$ and pH 8.4 at $40^{\circ}C$, respectively. The denatured enzyme recovered most of its $\gamma$-GTP activity by removing detergents such as sodium dodecyl sulfate (SDS) or urea with dialysis. The enzyme showed higher affinities against a number of amino acids as $\gamma$-glutamyl acceptors than glycylglycine in the following order: L-valine, L-methionine, L-glutamic acid or L-as-paragine, L-alanine. Also, it was shown that L-glutamine was the most suitable $\gamma$-glutamyl donor for the transfer reaction among those tested. Amino acids generally inhibited the enzyme activity for the transfer reaction, but not for the hydrolysis reaction.