• Korean System Dynamics Review
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• 제6권2호
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• pp.25-35
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• 2005

This paper describes the mechanism for new investment to appear in waves of boom and bust causing alternative periods of over and under supply of electricity in Korean market. A system dynamics model was developed to describe the dynamic behavior of new investment in Korean market. The simulation results show the boom and bust cycle in the new investments. When the market price is high, investors decide to build new power plants. However, it takes some delay time to complete new power plants. When the new power plants are being added into the grid, the supply increases and the wholesale price begins to decrease. This causes the cancellation of new power plant or delay the construction. This mechanism causes the boom and bust cycle in new investment.

• Journal of Internet Computing and Services
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• 제19권1호
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• pp.155-166
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• 2018

These days, online media, such as blogospheres, online communities, and social networking sites, provides the uncountable user-generated content (UGC) to discover market intelligence and business insight with. The business has been interested in consumers, and constantly requires the approach to identify consumers' opinions and competitive advantage in the competing market. Analyzing consumers' opinion about oneself and rivals can help decision makers to gain in-depth and fine-grained understanding on the human and social behavioral dynamics underlying the competition. In order to accomplish the comparison study for rival products and companies, we attempted to do competitive analysis using text mining with online UGC for two popular and competing ramens, a market leader and a market follower, in the Korean instant noodle market. Furthermore, to overcome the lack of the Korean sentiment lexicon, we developed the domain specific sentiment dictionary of Korean texts. We gathered 19,386 pieces of blogs and forum messages, developed the Korean sentiment dictionary, and defined the taxonomy for categorization. In the context of our study, we employed sentiment analysis to present consumers' opinion and statistical analysis to demonstrate the differences between the competitors. Our results show that the sentiment portrayed by the text mining clearly differentiate the two rival noodles and convincingly confirm that one is a market leader and the other is a follower. In this regard, we expect this comparison can help business decision makers to understand rich in-depth competitive intelligence hidden in the social media.

• Journal of the Korean Institute of Navigation
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• 제23권1호
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• pp.75-84
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• 1999

Although many studies on modelling of port competitive situation have been conducted, both theoretical frame and methodology are still very weak. In this study, therefore, a new algorithm called ESD (Extensional System Dynamics) for the evaluation of port competition was presented, and applied to simulate port systems in northeast asia. The detailed objectives of this paper are to develop Unit fort Model by using SD(System Dynamics) method; to develop Competitive Port Model by ESD method; to perform sensitivity analysis by altering parameters, and to propose port development strategies. For these the algorithm for the evaluation of part's competition was developed in two steps. Firstly, SD method was adopted to develop the Unit Port models, and secondly HFP(Hierarchical Fuzzy Process) method was introduced to expand previous SD method. The proposed models were then developed and applied to the five ports - Pusan, Kobe, Yokohama, Kaoshiung, Keelung - with real data on each ports, and several findings were derived. Firstly, the extraction of factors for Unit Port was accomplished by consultation of experts such as research worker, professor, research fellows related to harbor, and expert group, and finally, five factor groups - location, facility, service, cargo volumes, and port charge - were obtained. Secondly, system's structure consisting of feedback loop was found easily by location of representative and detailed factors on keyword network of STGB map. Using these keyword network, feedback loop was found. Thirdly, for the target year of 2003, the simulation for Pusan port revealed that liner's number would be increased from 829 ships to 1,450 ships and container cargo volumes increased from 4.56 million TEU to 7.74 million TEU. It also revealed that because of increased liners and container cargo volumes, length of berth should be expanded from 2,162m to 4,729m. This berth expansion was resulted in the decrease of congested ship's number from 97 to 11. It was also found that port's charge had a fluctuation. Results of simulation for Kobe, Yokohama, Kaoshiung, Keelung in northeast asia were also acquired. Finally, the inter port competition models developed by ESB method were used to simulate container cargo volumes for Pusan port. The results revealed that under competitive situation container cargo volume was smaller than non-competitive situation, which means Pusan port is lack of competitive power to other ports. Developed models in this study were then applied to estimate change of container cargo volumes in competitive relation by altering several parameters. And, the results were found to be very helpful for port mangers who are in charge of planning of port development.

• Management Science and Financial Engineering
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• 제16권3호
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• pp.49-70
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• 2010

Customer population management models can be classified into three categories: the first category includes the models that analyze the customer population at cohort level; the second one deals with the customer population at aggregate level; the third one has interest in the interactions among the customer populations in the competitive market. Our study proposes a model that can analyze the dynamics of customer population in consumer-durables market at aggregate level. The dynamics of customer population includes the retention curves from the purchase or at a specific duration time, the duration time expectancy at a specific duration time, and customer population growth or decline including net replacement rate, intrinsic rate of increase, and the generation time of customer population. For this study, we adopt mathematical ecology models, redefine them, and restructure interdisciplinary models to analyze the dynamics of customer population at aggregate level. We use the data of previous research on dynamic customer population management at cohort level to compare its results with those of ours and to demonstrate the useful analytical effects which the precious research cannot provide for marketers.

• Korean System Dynamics Review
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• 제4권1호
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• pp.33-53
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• 2003

How to maintain the optimal electric power generation mix is one of the important problems in electric power industry. The objective of this study is to develop a computer model which can be used to forecast the investment in power generation unit by the plant owners after restructuring of electric power industry. Restructuring of electric power industry will make difference in decision making process of investment in power generation unit. After Privatiazation of Power Industry, Gencos will think that profit is the most important factor among all others attracting the investment in the industry. Coal power generation is better than LNG CCGT in terms of profit. However, many studies show that LNG CCGT will be main electric power generation source because the rest of factors other than profit in LNG CCGT are superior than Coal power generation. Because the nst of factors other than profit in LNG CCGT are superior than Coal power generation. The impacts of the various government policies can be analyzed using the computer model, thus the government can formulate effective policies for achieving the desired electric power generation mix.

• Journal of Ecology and Environment
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• 제30권4호
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• pp.347-356
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• 2007

The structure and dynamics of Korean red pine stands established in the riparian zone were studied in the Tsang stream in Mt. Seorak National Park, in east-central Korea. Pine stands were classified into four successional stages, the initial, establishing, competitive, and stabilizing stages, based on the age distribution of a dominant tree, Pinus densiflora, the vegetation stratification, and the microtopography of the riverine environment. The stages usually corresponded to disturbance frequencies, depending on the horizontal and vertical distances from the watercourse. Stands of the initial and establishing stages lacked tree or subtree layers, or both. As stands progressed through the developmental stages, soil particle size became finer and moisture retention capacity was improved. The stand ordination reflected the developmental stage, and the species ordination differentiated species specializing in relatively dry and wet habitats. The results of the analysis of vegetation dynamics provided ecological information which will be useful for understanding the developmental processes of vegetation established in riparian zones. Species diversity indices usually increased across developmental stages, following the typical pattern for successional processes. We discuss the importance and necessity of riparian vegetation in Korea, where most riparian forests have disappeared due to excessive human land use.

• The Plant Pathology Journal
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• 제17권3호
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• pp.149-153
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• 2001

A total of 2109 isolates of Botrytis cinerea were collected from infected plants fo strawberry, tomato, and cucumber in Korea from 1994 to 1996. Based on in virtotests for mycelial growth on potato-dextrose agar containing fungicides, the esolates were classified into six phenotypic groups : SSR, SRR, RSS, RRS, RSR, and RRR, representing sensitivity (S) or resistance (R) to carbendazim, procymidone, and diethofencarb. In that order the isolation frequencies of the SSR, SRR, RSS, RRS, RSR, and RRR phenotypes were 28.7, 1.1, 28.8, 39.4, 1.0, and 0.9%, respectively. Three isolates from each SSR, SRR, RSS, RRS, and RSR and an isolate of RRR phenotype were selected and evaluated for their fitness-related characteristics such as pathogenic aggressiveness, mycelial growth rate, sporulation, and sclerotial formation. Competitive abilities of the SSR, SRR, RSS, RRS, and RSR phenotypes were also compared by inculating mixtures of conidial suspensions of two phenotypes to cucumber plant, and then determining re-isolation frequencies from lesions. In general, significant differences in fitness-related characteristics, except pathogenic aggressiveness, were found not only between but also within phenotype groups. In the competitiveness tests, carbendazim-sinsitive phenotypes (SSR and SRR) were found to be more competitive than the resistant ones (RSS and RSR), whereas, the procymidone-resistant phenotypes (SRR and RRS) appeared to be more competitive than the sensitive ones (SSR, RSS, and RSR). There was no consistent dominance in competitiveness between the diethofencarb-resistant and sensitive phenotypes. The RSR phenotype was the least competitive among the five phenotypes.

• Journal of Microbiology and Biotechnology
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• 제12권5호
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• pp.801-806
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• 2002

A multiplex competitive polymerase chain reaction (PCR) method was developed for the rapid identification and quantification of Leuconostoc mesnteroides and Lactobacillus plantarum populations which are the key microorganisms in kimchi fermentation. The strain-specific primers were designed to selectively amplify the target genes encoding 165 rRNA of L. plantarum and dextransucrase of L. mesenteroides. There was a linear relationship between the band intensity of PCR products and the number of colony forming units of each model organism. The PCR quantification method was compared with a traditional plate-counting method f3r the enumeration of the two lactic acid bacteria in a mixed suspension culture and also applied to a real food system, namely, watery kimchi. The population dynamics of the two model organisms in the mixed culture were reliably predictable by the competitive PCR analysis.

• Journal of Microbiology and Biotechnology
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• 제17권1호
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• pp.180-185
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• 2007

R-type pyocin is a bacteriophage tail-shaped bacteriocin produced by Pseudomonas aeruginosa, but its physiological roles are relatively unknown. Here we describe a role of R-type pyocin in the competitive growth advantages between P aeruginosa strains. Partial purification and gene disruption revealed that the major killing activity from the culture supernatant of PA14 is attributed to R-type pyocin, neither F-type nor S-type pyocins. These findings may provide insight into the forces governing P aeruginosa population dynamics to promote and maintain its biodiversity.

• Korean Journal of Organic Agriculture
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• 제23권4호
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• pp.683-702
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• 2015

The static status and dynamic trend of the market structure in the international wheat trade market are empirically analyzed. The export inequality level empirically proved to be high compared to import inequality level. And such states have been maintained since 2001 until 2014. Although the concentration level of export side seems to be easing, the international wheat market remains imperfect competitive market. Moreover, overall imperfect competitive status over 2002-2014 has been worsened compared to 2001 level. The main reasons are that the overall trends of the imports concentration is reduced more than those of the export concentration level.