• Journal of the Korea Concrete Institute
• /
• v.14 no.2
• /
• pp.137-147
• /
• 2002

Maturity models involving curing temperature and curing ages have been widely used to predict concrete strength, which can accurately estimate concrete strength. However, they may not consider physical quantities such as the characteristics of hydrates and the capillary porosity of microstructures associated with strength development. In order to find out the effects of both factors on a strength increment, the hydration model and the estimation method of the amount of capillary porosity were established, and the compressive strength test of concrete nth various water/cement ratios was carried out considering two test parameters, curing temperature and curing age. In this study, by analyzing the experimental results, a strength estimation model for early-age concrete that can consider the microstructural characteristics such as hydrates and capillary porosity was proposed. Measured compressive strengths were compared with estimated strengths and good agreements were obtained. Consequently, the proposed strength model can estimate compressive strength of concrete with curing age and curing temperature within an acceptable error.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.44 no.2
• /
• pp.149-153
• /
• 1999

Prediction of rice developmental stage is necessary for proper crop management and a prerequisite for growth simulation as well. The objectives of the present study were to find out the relationship between the plastochrone index(PI) and the developmental index(DVI) estimated by non-parametric phenology model which simulates the duration from seedling emergence(DVI=0) to heading(DVI=l) by employing daily mean air temperature and daylength as predictor variables, and to confirm the correspondency of developmental indice to panicle developmental stages based on this relationship. Four japonica rice cultivars, Kwanakbyeo, Sangpungbyeo, Dongjinbyeo, and Palgumbyeo which range from very early to very late in maturity, were grown by sowing directly in dry paddy field five times at an interval of two weeks. Data for seedling emergence, leaf appearance, differentiation stage of primary rachis branch and heading were collected. The non-parametric phenology model predicted well the duration from seedling emergence to heading with errors of less than three days in all sowings and cultivars. PI was calculated for every leaf appearance and related to the developmental index estimated for corresponding PI. The stepwise polynomial analysis produced highly significant square-rooted cubic or biquadratic equations depending on cultivars, and highly significant square-rooted biquadratic equation for pooled data across cultivars without any considerable reduction in accuracy compared to that for each cultivar. To confirm the applicability of this equation in predicting the panicle developmental stage, DVI at differentiation stage of primary rachis branch primordium was calculated by substituting PI with 82 corresponding to this stage, and the duration reaching this DVI from seedling emergence was estimated. The estimated duration revealed a good agreement with that observed in all sowings and cultivars. The deviations between the estimated and the observed were not greater than three days, and significant difference in accuracy was not found for predicting this developmental stage between those equations derived for each cultivar and for pooled data across all cultivars tested.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.17 no.3
• /
• pp.261-269
• /
• 2015

The purpose of this research is to identify the significance of climate factors related to the significance of change of dry matter yield (DMY) of whole crop maize (WCM) by year through the exploratory data analysis. The data (124 varieties; n=993 in 7 provinces) was prepared after deletion and modification of the insufficient and repetitive data from the results (124 varieties; n=1027 in 7 provinces) of import adaptation experiment done by National Agricultural Cooperation Federation. WCM was classified into early-maturity (25 varieties, n=200), mid-maturity (40 varieties, n=409), late-maturity (27 varieties, n=234) and others (32 varieties, n=150) based on relative maturity and days to silking. For determining climate factors, 6 weather variables were generated using weather data. For detecting DMY and climate factors, SPSS21.0 was used for operating descriptive statistics and Shapiro-Wilk test. Mean DMY by year was classified into upper and lower groups, and a statistically significant difference in DMY was found between two groups (p<0.05). To find the reasons of significant difference between two groups, after statistics analysis of the climate variables, it was found that Seeding-Harvesting Accumulated Growing Degree Days (SHAGDD), Seeding-Harvesting Precipitation (SHP) and Seeding-Harvesting Hour of sunshine (SHH) were significantly different between two groups (p<0.05), whereas Seeding-Harvesting number of Days with Precipitation (SHDP) had no significant effects on DMY (p>0.05). These results indicate that the SHAGDD, SHP and SHH are related to DMY of WCM, but the comparison of R2 among three variables (SHAGDD, SHP and SHH) couldn't be obtained which is needed to be done by regression analysis as well as the prediction model of DMY in the future study.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.24 no.3
• /
• pp.164-178
• /
• 2022

Uncertainties in weather forecasts would affect the reliability of yield prediction using crop models. The objective of this study was to compare uncertainty in crop yield prediction caused by the use of the weather forecast data. Daily weather data were produced at 10 km spatial resolution using W eather Research and Forecasting (W RF) model. The nearest neighbor method was used to downscale these data at the resolution of 5 km (W RF5K). Parameter-elevation Regressions on Independent Slopes Model (PRISM) was also applied to the WRF data to produce the weather data at the same resolution. W RF5K and PRISM data were used as inputs to the CROPGRO-SOYBEAN model to predict crop yield. The uncertainties of the gridded data were analyzed using cumulative growing degree days (CGDD) and cumulative solar radiation (CSRAD) during the soybean growing seasons for the crop of interest. The degree of agreement (DOA) statistics including structural similarity index were determined for the crop model outputs. Our results indicated that the DOA statistics for CGDD were correlated with that for the maturity dates predicted using WRF5K and PRISM data. Yield forecasts had small values of the DOA statistics when large spatial disagreement occured between maturity dates predicted using WRF5K and PRISM. These results suggest that the spatial uncertainties in temperature data would affect the reliability of the phenology and, as a result, yield predictions at a greater degree than those in solar radiation data. This merits further studies to assess the uncertainties of crop yield forecasts using a wide range of crop calendars.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.19 no.4
• /
• pp.246-251
• /
• 2017

Crop models have been used to predict a heading date for efficient management of fertilizer application. Recently, the ORYZA (v3) model was developed to improve the ORYZA2000 model, which has been used for simulation of rice growth in Korea. Still, little effort has been made to assess applicability of the ORYZA (v3) model to rice farms in Korea. The objective of this study was to evaluate reliability of heading dates predicted using the the ORYZA (v3) model, which would indicate applicability of the model to a decision support system for fertilizer application. Field experiments were conducted from 2015-2016 at the Rural Development Administration (RDA) to obtain rice phenology data. Shindongjin cultivar which is mid-late maturity type was grown under a conventional fertilizer management, e.g., application of fertilizer at the rate of 11 Kg N/10a. Another set of heading dates was obtained from annual reports at experiment farms operated by the National Institute of Crop Science and Agricultural Technology Centers in each province. The input files for the ORYZA (v3) model were prepared using weather and soil data collected from the Korean Meteorology Administration (KMA) and the Korean Soil Information System, respectively. Input parameters for crop management, e.g., transplanting date and planting density, were set to represent management used for the field experiment. The ORYZA (v3) model predicted heading date within 1 day for two seasons. The crop model also had a relatively small error in prediction of heading date for three ecotypes of rice cultivars at experiment farms where weather input data were obtained from a near-by weather station. Those results suggested that the ORYZA (v3) model would be useful for development of a decision support system for fertilizer application when reliable input data for weather variables become available.

• Journal of the Korea Society of Computer and Information
• /
• v.18 no.4
• /
• pp.97-112
• /
• 2013

The quality of the data is the most basic prerequisite for effective use of data. Problems and the resulting loss due to error data has emerged using case studies and a number of, to a national, quality certification system of the data has been enforced, you must manage to generate data study on the method for selecting the point of view of an organization's data CTQ is a very unsatisfactory state of affairs. Selected CTQ main data is subject to quality control in the organization, to develop criteria for CTQ data side of the business and IT so that it can be managed in a systematic manner, the proposed model, to filter the data accordingly presented in detail how to manage enterprise-wide CTQ data that can be quantified Te. By utilizing SPSS, factor analyzes, for which I used the AHP method for quantification. In particular, we present a framework of management measures along the maturity of the data in the organization due to the enforcement of authentic quality certification system of DB, utilizing the CTQ-DSMM model readily applicable to practice.

• The Journal of the Korea Contents Association
• /
• v.9 no.12
• /
• pp.710-717
• /
• 2009

The researchers and planners are using patent/paper map system to analyze the research trend, but we can't use the existing analysis system because of the specialty of korean traditional medicine. Thus we deduced the analysis models from preceding research and system and designed 14 analysis models which are composed of basic, detail and complex models. We verified the analysis models using papers which has 'meridian' keyword among 16,000 papers stored in OASIS. From the analysis result, we know that the meridian study has just entered in the maturity and is closely related with other parts of korean traditional medicine as physiology etc. And we verified the proposed analysis model from the comparison with the analysis models of preceding systems. The analysis model will be used for the development of Korean traditional medicine paper map analysis service scenario and system.

• The Journal of the Korea Contents Association
• /
• v.8 no.1
• /
• pp.27-38
• /
• 2008

Since the current mobile web market is already in its maturity, a research concerning the continued behavior of mobile Internet users should be carried out. The purpose of this research is to understand user's continued behaviors by theoretically constructing and empirically testing a continued model using real usage data. The model consists of four post-expectation factors (usefulness, ease of use, enjoyment, and perceived value) as well as user satisfaction, continuance intention, and the actual usage amount. To test the model, an on-line survey had been conducted, and we collected the actual usage data of survey respondents via the support of telecommunication companies. The study results indicate that post expectation variables were found to influence satisfaction, continuance intention, and actual usage amount of mobile web users. This paper ends with study limitations and implications on mobile web industry.

• Journal of the Korean Home Economics Association
• /
• v.33 no.4
• /
• pp.173-188
• /
• 1995

This study examined the characteristics of the relationship of HOME, sociodemographic variables and children's verbal ability at age four, five, six, Expecially this study investigated causal relationships amoong the variables which are supposed to affect children's verbal ability by children's age and sex. The subject of this study were 180 children and their mothers. Instruments included inventory of home stimulation(HOME), inventory of socio-demographic variables, inventory of the children's verbla ability. The results obtained from this study were as follows : 1. For the most part, HOME and socio-demographic variables had a significant positive correlation with children's verbal ability. 2. The variables that significantly predicted children's verbal ability differed according to children's age and sex. That is, play materials, breadth of experience and economic status of the home were predictive of boy's verbal ability at age four, while aspects of physical environment, breadth of experience were predictive at age five, fostering maturity and independence, parent's education were predictive at age six. And developmental stimulation and breadth of experience were predictive of girl's verbal ability at age four, while developmental stimulation, economic status of the home were predictive at age five, developmental stimulation and play materials were predictive at age six. 3. the results of the analysis of the causal model showed that the kind of variables that affected children's verbal ability directly differed according to children's age and sex. That is, indirect stimulation and direct stimulation affected boy's verbal ability directly at age four and five, while indirect stimulation and parent's education affected boy's verbal ability at age six. And indirect stimulation, direct stimulation, emotional climate of the home affected girl's verbal ability directly at age four, while direct stimulation, economic status of the home, indirect stimulation affected directly at age five, parent's education, indirect stimulation and direct stimulation affected girl's verbal ability at age six. 4. Another causal model of the HOME, socio-demographic variables affecting children's verbal ability showed that total HOME scores more significantly affected boys and girl's verbal ability directly than socio-demographic variables at all ages.

• Journal of Plant Biotechnology
• /
• v.5 no.4
• /
• pp.221-224
• /
• 2003

Leaf explants of Ixeris sonchifolia produced adventitious shoots at a frequency of 100% when cultured on MS medium supplemented with combinations of various concentrations of 6-benzyladenine (BA) (0.44, 4.44, or 8.87 ${\mu}M$) and 0.54 ${\mu}M$ NAA, or MS medium supplemented with 22.19 ${\mu}M$ BA and 2.69 ${\mu}M\;\alpha$-naphthaleneacetic acid (NAA) after four weeks of culture. Each explants (approximately $3{\times}6mm$) produced greater than 70 shoots at a combination of 0.44 ${\mu}M$ BA and 0.54 ${\mu}M$ NAA. Leaf explants produced shoots at a frequency of greater than 80% even at as low as 0.13 ${\mu}M$ BA as the sole growth regulator. Upon transfer to one-third strength MS with 0.54 ${\mu}M$ NAA, excised adventitious shoots were rooted at a frequency of 100%. Regenerated plantlets were transplanted to potting soil and grown to maturity in a greenhouse. The competence of I. sonchifolia for plant regeneration via organogenesis appears to be greater than the competence of tobacco, currently the best model plant for organogenesis.