• Journal of Bio-Environment Control
• /
• v.10 no.2
• /
• pp.125-131
• /
• 2001

The objective of this study was to estimate the amount of nutrient and water taken up at different growth stages by cucumber (Cucumis sativus L. cv. Eunsung Backdadagi) grown in a closed substrate culture system. The amount of nutrient solution absorbed increased in proportion to days from planting at the first stage of growth and depended on the level of radiation after the mid stage of growth. After the mid growth stage, the amount of nutrient solution absorption was maintained at 80-100 mg.MJ$^{-1}$ . Total amount of absorbed inorganic ions except S increased since the nutrient solution absorption increased with the level of radiation, although the absorption rate of each inorganic ion declined. A highly significant correlation ($R^2$>0.9) was found between amount of inorganic ions absorbed and days after planting, LAI, total dry weight and leaf dry weight, but not with CGR. Correlation coefficient between days after planting and the amount of nutrient solution absorbed per unit radiation level was 0.92. Correlation coefficient between leaf area an the amount of nutrient solution absorbed per unit radiation level was 0.97. Regression of the amount of nutrient solution absorbed per unit radiation level and nutrient ions uptake showed a high significance ($R^2$>0.9).

• Korean Journal of Weed Science
• /
• v.30 no.2
• /
• pp.94-102
• /
• 2010

Field and pot experiments were conducted to investigate seedling emergence and early growth of Eleocharis kuroguwai panted on different dates. Non-linear regression analyses of observed data against effective accumulated temperature (EAT) with the Gompertz model showed that the Gompertz model works well in describing seedling emergence and early growth of E. kuroguwai regardless of planting date and soil burial depth. EATs required for 50% of the maximum seedling emergence of E. kuroguwai planted at 1, 3 and 5 cm soil burial depth in the pot experiment were estimated to be 54.5, 84.0 and $118.0^{\circ}C$, respectively, and $56.7^{\circ}C$ when planted at 1 cm in the field experiment. EATs required for 50% of the maximum leaf number of E. kuroguwai planted at 1, 3 and 5 cm soil burial depth in the pot experiment were estimated to be 213.3, 249.0 and $291.6^{\circ}C$, respectively, and $239.5^{\circ}C$ when planted at 1 cm in the field experiment. Therefore, models developed in this study thus predicted that if rotary tillage with water is made on 27 May under $+2^{\circ}C$ elevated temperature condition, dates for 50% of the maximum seedling emergence, 5 leaf stage and 5 cm plant height of E. kuroguwai buried at 3 cm soil depth were predicted to be 2 June, 10 June and 12 June. These dates are 1 day earlier for the seedling emergence and 3 days earlier for the early growth as compared with current temperature condition, suggesting that earlier application of herbicides is required for effective control of E. kuroguwai.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.35 no.4
• /
• pp.386-394
• /
• 2002

Carrying capacity model focused on interactions between the filter-feeder growth and their environments is presented, and differences among existing various carrying capacity models are reviewed. For carrying capacity modeling of shellfish system, we constructed a new numerical model coupled oyster growth model with an ecosystem model (EUTRP2). Physical and biological processes such as water transport and mixing, primary production, feeding and growth of the cultivated oyster, Crassostrea gigas and benthic-pelagic exchange were included in the model, Simulated results for validation showed that the more phytoplankton biomass decreased, the more oyster meat weight and nutrients increased, suggesting a powerful tool for reasonable management of shellfish aquaculture. The model was sensitive to parameters controlling the primary production. Among the ecosystem compartments, the oyster growth is highly influenced by small changes in the physiological parameters of phytoplankton and oyster. This sensitivity analysis indicated the importance of experimental data on biological parameters for calibration of the model.

• Education of Primary School Mathematics
• /
• v.24 no.1
• /
• pp.1-20
• /
• 2021

Factors influencing mathematics academic achievement are constantly changing and have direct and indirect effects on mathematics achievement, so longitudinal studies that can predict and analyze their growth are needed. This study uses longitudinal data on students from 2011 (5th grade of elementary school) to 2015 (2nd grade of middle school) of the Seoul Education Longitudinal Study, and divides them into groups with similar longitudinal changes in mathematics academic achievement. The direct and indirect effects of learning attitudes and achievement goals were examined. As a result of the study, it was found that learning effort and learning attitude had a direct effect on mathematics achievement in 1 group (2277 students, 67.7%), and learning attitude had a direct effect on mathematics achievement in 3 groups (958 students, 28.5%). And it was found that learning effort h ad an indirect effect. In addition, it was found that both learning attitudes, learning efforts, and achievement goals had no effect on the academic achievement of mathematics in the second group (127 students, 3.8%).

• The Journal of the Korea Contents Association
• /
• v.14 no.4
• /
• pp.325-335
• /
• 2014

This study provides an overview of instruments for mobile contents start-up companies promotion that are currently available in Seoul. It includes a brief description of several different types of start-up companies and development processes for each of those companies so that it can analyze and figure out critical success factors for sustainable growth. In addition, the case studies of five mobile contents related companies are used to obtain more detailed insights into the development processes. The study focuses on mobile contents startups promotion used as a public policy for encouraging more productive and knowledge-intensive ventures, with the aim of upgrading management activities and creating more startups-friendly business environment. Consequently, the key target groups of the measures discussed in the study include mobile contents start-ups and start-ups that exploit new business opportunities in Seoul.

• Journal of the Korea Society of Computer and Information
• /
• v.25 no.3
• /
• pp.65-72
• /
• 2020

With the development of information technology and the growth of the scale of system and network, cyber threats and crimes continue to increase. To cope with these threats, cybersecurity training based on actual attacks and defenses is required. However, cybersecurity training requires expert analysis and attack performance, which is inefficient in terms of cost and time. In this paper, we propose a cyber attack simulator that automatically executes attack techniques. This simulator generates attack scenarios by combining attack techniques modeled to be implemented and executes the attack by sequentially executing the derived scenarios. In order to verify the effectiveness of the proposed attack simulator, we experimented by setting an example attack goal and scenarios in a real environment. The attack simulator successfully performed five attack techniques to gain administrator privileges.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.14 no.1
• /
• pp.57-65
• /
• 2011

The composition of species for each community of Quercus by vegetation and soil survey, the community classification by TWINSPAN, the structural characteristics of communities were used and analyzed during the period of 2000~2004 for Quercus mongolica forest. And the resulting suggestions for a subsequent planting model for forest are as follows. The Quercus mongolica community had the highest importance value for Quercus mongolica followed sequentially by Acer pseudosieboldianum, Acer mono, Rhododendron schlippenbachii, Tilia amurensis, Fraxinus rhynchophylla, and Fraxinus sieboldiana. As a result of suggesting a planting modeling for the Quercus mongolica communities in the areas with the warmth index of both $60.90{\sim}79.79^{\circ}C$ and $53.96{\sim}64.82^{\circ}C$, Quercus mongolica was absolutely dominant in case of the subtree layer for the accompaniment species of distribution in the planting modeling by tree layer in the two areas depending on the warmth index, while there were distinct differences shown in case of the lower tree layer. While Acer pseudosieboldianum, Tilia amurensis, Fraxinus rhynchophylla, Sorbus alnifolia, Acer mono, etc. were appeared in the subtree layer for the areas with the warmth index of $60.90{\sim}79.79^{\circ}C$. Cornus controversa, Quercus mongolica, Fraxinus sieboldiana, etc. were many appeared in the subtree layer for the areas with the warmth index of $53.96{\sim}64.82^{\circ}C$. And, when we made ecological Quercus mongolica community, subtree layer planting is different by warmth index.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.12
• /
• pp.3821-3828
• /
• 2000

Many software projects collect grouped failure data (failures in some failure interval or in variable time interval) rather than individual failure times or failure count data during the testing or operational phase. This paper presents the neural network (NN) modeling that is dble to predict cumulative failures in the variable future time for grouped failure data. ANN's predictive ability can be affected by what it learns and in its ledming sequence. Eleven training regimes that represents the input-output of NN are considered. The best training regimes dre selected rJdsed on the next' step dvemge reldtive prediction error (AE) and normalized AE (NAE). The suggested NN models are compared with other well-known KN models and statistical software reliability growth models (SHGlvls) in order to evaluate performance, Experimental results show that the NN model with variable time interval information is necessary in order to predict cumulative failures in the variable future time interval.

• Journal of Korean Society on Water Environment
• /
• v.23 no.5
• /
• pp.581-590
• /
• 2007

A float-type weir has been proposed for the control of algal blooms in some of eutrophic reservoirs recently. It is known as a costly and ecologically sound method, but there is little understanding about the sustainability of this low-cost technology for reservoirs that are located in monsoon climate areas where large flood events during the summer cause high water surface fluctuations. The objective of this study was to assess the effectiveness of a skimmer weir aimed at controlling algal blooms in the lacustrine zone and near the drinking water withdrawal structures of Daecheong Reservoir under various hydrodynamic flow conditions. The effect of weir on the control of algal blooms was simulated using a laterally averaged two-dimensional hydrodynamic and eutrophication model that can accommodate vertical displacement of the weir following the water surface fluctuations. Numerical simulations were performed for two different hydrological conditions, 2001 and 2004 for representing drought year and normal year, respectively. The results showed that the weir is very effective method to control algal blooms in the reservoir by curtailing the transport of phosphorus and algae from contaminated inflow to the downstream lacustrine epilimnion during the draught year. However, large flood events occurred in 2004 transported nutrients and algae built upstream of the weir into the downstream euphotic zone by strong entrainments.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.1 no.1
• /
• pp.20-26
• /
• 2006

One of the computer application fields which started showing noticeable new growth trends in recent years is the real time communication distributed computing application field. Object -oriented(OO) real time(RT) distributed computing is a form of real-time distributed computing realized with a distributed computer system structured in the form of an object network. In this paper, we describes the application environment as the DHS (distributed high-precision simulation) with TMO structure. The TMO scheme is aimed for enabling a great reduction of the designer's effort in guaranteeing timely service capabilities of distributed computing application systems. It has been formulated from the beginning with the objective of enabling design-time guaranteeing of timely action. In the real time simulation techniques based on TMO object modeling, we have observed several advantages to the TMO structuring scheme. TMO object modeling has a strong traceability between requirement specification and design, cost-effective high-coverage validation, autonomous subsystems, easy maintenance and flexible framework for requirement specification.