• Research in Plant Disease
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• v.24 no.1
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• pp.26-32
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• 2018

Fusarium wilt on strawberry plants caused by Fusarium oxysporum f. sp. fragariae (Fof) is a major disease in Korea. The prevalence of this disease is increasing, especially in hydroponic cultivation in strawberry field. This study assessed the effect of nutrition solution pH and electrical conductivity (EC) on Fusarium wilt in vitro and in field trials. pH levels of 5.0, 5.5, 6.0, 6.5, 7.0, and 7.5 were assayed in vitro and in field trials. EC levels at 0, 0.5, 0.8, 1.0, and $1.5dS{\cdot}m^{-1}$ were assayed in field trials. Mycelial growth of Fof increased with increasing pH and was highest at $25^{\circ}C$ pH 7 and lowest at $20^{\circ}C$, pH 5.0 in vitro. The incidence of Fusarium wilt was lowest in the pH 6.5 treatment and highest in the pH 5 treatment in field trials. At higher pH levels, the EC decreased in the drain solution and the potassium content of strawberry leaves increased. In the EC assay, the severity of Fusarium wilt and nitrogen content of leaves increased as the EC increased. These results indicate that Fusarium wilt is related to pH and EC in hydroponic culture of strawberry plants.

• Applied Biological Chemistry
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• v.34 no.2
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• pp.134-141
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• 1991

In order to investigate the changes and characteristics of biochemical metabolic substances of soybean tissue culture during the cultural period, immature cotyledons were detached form the plant on 15th days after flowering and cultured in vitro for 3 weeks. The cultures were classified into embryogenic(EC) and non-embryogenic callus(NEC). A part of the EC lines were subcultured for another 3 weeks and classified into root forming(RFC), and shoot forming cultures(SFC). Another part of the EC lines were used for isolation of protoplasts, which were subsequently cultured in vitro for 4 weeks. The cultures were classified into embryogenic(PEC) and non-embryogenic callus(PNEC) derived from the protoplasts. The cultures of EC and PEC lines showed higher phenylalanine content and lower methionine content than those of NEC and PNEC. At organ differentiation stage, both cultures showed the content of aspartic acid decreased, while the other amino acids increased as a whole. The protein pattern analysis of the cultures revealed that EC and NEC lines contained distinctive polypeptides, with mass of ca. 18KD for EC and ca. 22KD for NEC respectively. The EC and PEC lines also showed high activity of peroxidase isozyme A(piA), while the RFC and SFC lines showed that of peroxidase isozyme B(piB).

• Proceedings of the Korea Inteligent Information System Society Conference
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• 1999.10a
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• pp.281-289
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• 1999

The objective of this paper is to propose a brand new interface mechanism to provide more intelligent decision making support for EC problems. Its main virtue is based on a numerical process mechanism by using an Extended AND-OR Graph (EAOG)-based logic algebra. Using this mechanism, decision makers engaged in electronic commerce (EC) can effectively deal with complicated decision making problems. In the field of traditional expert systems research, AND-OR Graph approach has been suggested as a useful tool for representing the logic flowchart of the forward and/or backward chaining inference methods. However, the AND-OR Graph approach cannot be effectively used in the EC problems in which real-time problem-solving property should be highly required. In this sense, we propose the EAOG inference mechanism for EC problem-solving in which heurisric knowledge necessary for intelligent EC problem-solving can be represented in a form of matrix. Finally, we have proved the validity of our approach with several propositions and an illustrative EC example

• Korean Journal of Computational Design and Engineering
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• v.9 no.4
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• pp.315-324
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• 2004

The purpose of this study is to suggest the way of automatic building code checking for architectural drawings in the web environment to enhance the utility of CALS/EC standard drawings and efficiency of construction industry business. To fulfil this aim, the authors seek to standardize the architectural drawing automatic checking system by linked drawing information to the STEP based CALS/EC standard format. Therefore, the automatic building code checking system can represent a way of utilizing the relationship between the construction CALS/EC standard drawings and the related study as well as improve the efficient of the construction work by sharing a variety of drawing information.

• The Journal of Society for e-Business Studies
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• v.9 no.1
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• pp.237-254
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• 2004

A customer satisfaction at business activity has influence on affirmative customer reaction. The customer reaction encouragement system(CRES) is to expand the present customer response concept in this paper. The CRES application can make real-time connection between customers and sellers at EC(B2C) environment, and on the basis of this application, it can derive the positive customer reaction encouragement. In this paper, the comparison results between new EC system applied for the CRES and present EC system are proposed.

• The Journal of the Korea Contents Association
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• v.1 no.1
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• pp.32-40
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• 2001

EC(Electronic Commerce) reduces the middle love of business process and makes the gap doser between suppliers and consumers. EC also makes it possible to products and much more satisfaction to consumers reducing costs. Thus when we study EC, we need to consider business side of EC as well as its technical side. With that point, this study classifies the business factors of EC systematically. This study does not enumerate bits of the factors but present a business technology framework to analyze the mutual relations among the factors.

• Journal of the Korean Society for Library and Information Science
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• v.23
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• pp.1-31
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• 1992

The present study aims at a systematic access to EC information. EC information is the outcome of the complex organizations, the continuous changes in functions and the subsequent changes in policies. An attempt for an effective approach to the information requires the examination of the organizational structures and changes, the processes involved in formulating and implmenting the information policies, and the infrastucture for information. Information activities of the major organizations of EC have been examined with a special reference to the Commission of European Communities. The Commission is the EC institution from which the majority of the EC's documentation originates. The information functions of the Commission have been studied in such categories as information production and distribution, authorizing services, and information services to the public.

• The Journal of Society for e-Business Studies
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• v.3 no.2
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• pp.17-35
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• 1998

Global Electronic Commerce (EC) is currently being pursued by most of the developed countries. Domestically, EC has just started and still has lots of problems to solve in terms of both technology and institutions. EC has a great potential to affect a country's competitive advantage. For EC to be adopted and diffused early, it is necessary to analyze the current status of EC and to establish the strategies to strengthen the competitive position. Therefore, the major objectives of the study are to review the current status of EC in Korea and to propose for both public and private sectors the strategies to strengthen the competitive advantage.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.11a
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• pp.40-43
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• 2000

Groundwater qualities in Nakdong river region were investigated during 1999 and 2000. Groundwater samples were collected twice from about 150 sites over the region. The EC and TDS obtained in first survey (October, 1999) show rather high values than those in second survey(April, 2000) and this seems to be caused by groundwater temperature. There is obvious positive correlation between EC and TDS. For the study area, the following equation can be written : TDS(mg/l) = <0.64~0.70> x EC($mutextrm{s}$/cm). As the concentration of major ions increases in natural condition, there is a tendency that the ratio of TDS and EC has consistent value. This observation suggests that TDS measurement can be replaced by EC measurement in the some ranges.

• Journal of Bio-Environment Control
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• v.1 no.2
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• pp.162-168
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• 1992

As the automation of nutrient solution management proceeds in the field of hydroponics, effective supporting systems to manage the nutrient solution by computer become needed. This study was attempt to predict the EC of nutrient solution using the neural networks. The multilayer perceptron consisting of 3 layers with the back propagation learning algorithm was selected for EC prediction, of which nine variables in the input layer were the concentrations of each ion and one variable in the output layer the EC of nutrient solution. The meq unit in ion concentration was selected fir input variable in the input layer. After the 10,000 learning sweeps with 108 sample data, the comparison of predicted and measured ECs for 72 test data showed good agreements with the correlation coefficient of 0.998. In addition, the predicted ECs by neural network showed relatively equal or closer to the measured ones than those by current complicated models.