• Korean System Dynamics Review
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• v.15 no.3
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• pp.37-59
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• 2014

This paper is to study dynamics of populations of religions. As human population is a crucial source of social dynamics, the religious population is a driving force that changes political and cultural landscape of society. Although many christian scholars have reported important causal factors in changing population of christian world, there are few studies on the dynamics of religious population in system dynamics. This paper interprets these dynamic mechanisms in terms of feedback loops and constructs a basic system dynamic model to forecast future trend of religious population in Korean society.

• Korean System Dynamics Review
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• v.13 no.4
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• pp.5-31
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• 2012

This paper aims at investigating the dynamics between aging population and local finance. In recent years, the aging rate has been accelerating the pace. The trend implies that Korea is moving towards the aging society, presumably, with unprecedented speed in the world. Aging society's biggest problems are centered around the explosive growth of the financial needs. In particular, these problems are apt to appear more seriously in local governments, as most of them are confronted with high level of aging population and poor financial bases. Firstly, it analyzes how the population structure in the local government impacts local finance, income and expenditure. Based upon in-depth literature reviews, this study examines variables related to aging population and local fiance. Secondly, it focuses on a series of positive and negative feedback loops which would reveal the essence of the mutual interaction structure between aging population and local governments' fiscal behaviors.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.6
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• pp.820-824
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• 2010

Genetic algorithm is known to be an effective method to solve a global nonlinear optimization. However, a huge amount of calculation is needed to improve the dependability of the solution and thus Ga is not adequate for online implementation. In this paper, we propose an online nonlinear system identification scheme which employs population feedback genetic algorithm. The effectiveness of our scheme is shown by several simulations.

• Korean System Dynamics Review
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• v.11 no.3
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• pp.105-126
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• 2010

The ecology of house swallow is closely related to the humans life because their life depend on the human settlements conditions and environments. 30 years ago house swallows are very common at the country side, but recently they are very rare. Almost the number of house swallows decrease as 1 of hundredth during 20 years. Why this dramatic population decrease are happening in the ecology of house swallow? The Population size impacted by many factors such as nesting, breeding, feeding, returning. The objective of this paper is to analyse the population dynamics of the ecology of House Swallow. This paper focuses on the important ecological changes-nests, foods, and return rates from wintering area-associated with recent country side development. In this paper, we explore the feedback loops of population dynamics and simulate the policy scenario model.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.4
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• pp.67-75
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• 1998

In general, Evoluationary Algorithm(EAs) are refered to as methods of population-based optimization. And EAs are considered as very efficient methods of optimal sytem design because they can provice much opportunity for obtaining the global optimal solution. This paper presents a co-evolution scheme of artifical neural networks, which has two different, still cooperatively working, populations, called as a host popuation and a parasite population, respectively. Using the conventional generatic algorithm the host population is evolved in the given environment, and the parastie population composed of schemata is evolved to find useful schema for the host population. the structure of artificial neural network is a diagonal recurrent neural netork which has self-feedback loops only in its hidden nodes. To find optimal neural networks we should take into account the structure of the neural network as well as the adaptive parameters, weight of neurons. So we use the genetic algorithm that searches the structure of the neural network by the co-evolution mechanism, and for the weights learning we adopted the evolutionary stategies. As a results of co-evolution we will find the optimal structure of the neural network in a short time with a small population. The validity and effectiveness of the proposed method are inspected by applying it to the stabilization and position control of the invered-pendulum system. And we will show that the result of co-evolution is better than that of the conventioal genetic algorithm.

• Journal of Ecology and Environment
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• v.33 no.4
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• pp.317-323
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• 2010

Nutrient availability is a critical component of agroecosystems, and is relevant to both above- and below- ground interactions. The principal objective of this study was to determine how the cessation of fertilization affects the communities of weeds and soil organisms in a corn/wheat field. Changes in dominant weed species, substrate-induced respiration, and the population density of nematodes and microarthropods were evaluated. Microbial substrate-induced respiration (SIR) and the population density of microarthropods decreased following the cessation of fertilization and were partly correlated with the aboveground weed biomass. The cessation of organic fertilizer application but continuing application of inorganic fertilizer reduced the population density of nematodes. In response to the cessation of fertilization, weed communities were dominated by species with little dependency on fertilization. Amaranthus retroflexus was identified as the most dominant species in the corn field; however, it was replaced by Digitaria ciliaris after the cessation of fertilization. In the wheat field, the cessation of fertilization led to a rapid reduction in the biomass of most weeds, except for Vicia angustifolia, supposedly as the result of symbiotic nitrogen fixation. Additionally, the fact that weed biomass was partially correlated with SIR or the population density of microarthropods may reflect a mutual feedback between soil organisms and weeds. The results indicate that the cessation of fertilization alters communities of weeds and soil organisms through changes in weed biomass and interactions with symbiotic microorganisms.

• Journal of applied mathematics & informatics
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• v.29 no.5_6
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• pp.1193-1204
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• 2011

In the present paper we consider a differential-algebraic prey-predator model with stage structure for prey and harvesting of predator species. Stability and instability of the equilibrium points are discussed and it is observed that the model exhibits a singular induced bifurcation when the economic profit is zero. It indicates that the zero economic profit brings impulse, i.e. rapid expansion of the population and the system collapses. For the purpose of stabilizing the system around the positive equilibrium, a state feedback controller is designed. Finally, numerical simulations are given to show the consistency with theoretical analysis.

• Korean journal of applied entomology
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• v.38 no.3
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• pp.231-240
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• 1999

The long-term tend an pattern changes of Chilo suppressalis(Walker) occurrence in Suwon were analyzed and the forecasting models for spring emergence of C. suppressalis in Suwon were developed. From 1965 to 196, the population dynamics of C. suppressalis in Suwon shows a cyclic fluctuation with one large peak an one small peak, and its periodicity was ca. 36 generations(18 years). C. suppressalis population dynamics in Suwon was characterized as controlled by the endogenous dynamics dictated by the 1st order negative feedback mechanism (fast density dependence). The dynaics mechanism of C. suppressalis populations was not changed although its population density decreased drastically over the years. Using th dta of C. suppressalis spring occurrence in Suwon, forecasting models for spring emergence of C.supressalis were developed based on temperature-dependent development model or degree days. In general, these models well described the C. suppressalis spring emergence pattern in Suwon. Also, forecasting problems in spring moth emergence related with C. suppressalis population dynamics were discussed.

• Parasites, Hosts and Diseases
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• v.54 no.4
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• pp.399-405
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• 2016

Poor subsistence farmers who live in a semi-arid area of northern Ethiopia build irrigation systems to overcome water shortages. However, there is a high risk of malaria transmission when increased standing water provides more favorable habitats for mosquito breeding. This is a serious problem because there are many barriers to malaria control measures and health care systems in the area. Using a causal loop diagram and computer simulations, the author attempted to visually illustrate positive and negative feedbacks between mosquito and human populations in the context of Simret, which is a small village located in northern Ethiopia and is generally considered a malaria-free area. The simulation results show that the number of infectious mosquitos increases to 17,215 at its peak, accounting for 3.5% of potentially dangerous mosquitos. At the same time, the number of sick people increases to 574 at its peak, accounting for 15% of local population. The malaria outbreak is controlled largely because of a fixed number of vulnerable people or local population that acts as an intermediate host.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.43.1-43.1
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• 2014

We report on the optical spectroscopic analysis of a Low Luminosity Quasi Stellar Objects (LLQSOs) sample at $z{\leq}0.06$ based on the Hamburg/ESO QSO survey (HES). To better relate the low-redshift Active Galactic Nucleus (AGN) to the QSO population it is important to study samples of the latter type at a level of detail similar to that of the low-redshift AGN. Powerful QSOs, however, are absent at low redshifts due to evolutionary effects and their small space density. Our understanding of the (distant) QSO population is, therefore, significantly limited by angular resolution and sensitivity. The LLQSOs presented here offer the possibility to study the faint end of this population at smaller cosmological distances and, therefore, in greater detail. This, in turn, provides information about the key ingredients with respect to fueling and feedback of QSOs, and their relative importance/strength. Here, we present results of the analysis of visible wavelength spectroscopy provided by the HES and the 6 Degree Field Galaxy Survey (6dFGS). Interesting differences in the taxonomy of the sources having both types of spectra have been noticed and will be discussed.