• Korean Journal of Soil Science and Fertilizer
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• v.21 no.4
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• pp.373-379
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• 1988

This experiment was carried out to investigate the effects of long-term applications of rice straw and compost on the physical and mechanical properties of paddy fields and the yearly variation of rice yield in Fluvio-Marine plain of Jeonbug series. Amounts of rice straw and compost applied in this experiment were 500kg/10a, 1,000kg/10a respectively, and the nitrogen levels were 0, 15 and 20kg/10a. This experiment were continued for 9 years from 1979 to 1987. The results are summarized as follows: 1. Clay and silt ratios were decreased but versa in sand ratio, by the long-term application of rice straw and compost. 2. Bulk density in the long-term application of organic matter was lower in surface soil of non-application than nitrogen application (15kg/10a) and in rice straw than compost. 3. Solid ratio went down, but liquid and gaseous ratio went up especially, by organic matter application liquid ratio were increased by compost and gaseous ratio were increased by in rice straw. 4. Aggregates of bigger than 2mm were increased by long-term application of organic matter, and the effects was better in rice straw than compost. Accumulative aggregate of 2mm was 66.5% in nitrogen of 15kg/ 10a with rice straw, which showed the increase of 9.1% in comparison with the non-application of nitrogen and organic matter. 5. Liquid limit, plastic limit and plastic index were high in order of rice straw, compost and control, and liquid index was lower in compost than in rice straw. 6. Cole value was higher in vertical than horizontal and highest in the application of rice straw with nitrogen of 15kg/10a. Cone and shearing resistance were lowest in the application of rice straw with nitrogen. In total vertical pressure friction was higher in the long-term application of organic matter than control. 7. The change of yield index was higher in the long-term application of compost than rice straw in non-nitrogen and it showed the yearly competitive variation between the long-term application of compost and rice straw in nitrogen of 10kg/10a. In nitrogen application of 20kg/10a, it was increased from 6th year by rice straw application.

• Korean Journal of Animal Reproduction
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• v.24 no.3
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• pp.249-254
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• 2000

This study was carried out to investigate the possibility of dehydroepiandrosterone sulphate(DHEAS) as a stress hormone. Experiment 1) We evaluated the variation of DHEAS levels of long-term(30minutes a day fur 3 weeks) 37$^{\circ}C$ thermal stressed mice compared with that of cortisol. Serum concentrations of cortisol and DHEAS were measured by radioimmunoassay(RIA). Cortisol levels were not significantly altered both LW(Long-term stressed group, mice were killed without rest) and LR(Long-term stressed group, mice were killed after 4 days' rest) compared with control group, but DHEAS levels were decreased in LW compared with control group(p<0.05), and it kept a sustained difference after 4 days' rest(LR)(p<0.05). Experiment 2) We evaluated the changes of DHEAS levels on term of stress and rest. As stress term was longer, serum DHEAS levels were decreased and also kept a sustained difference after 10 days' rest compared with control group(p<0.05). These results suggest that cortisol has difficulty in taking an accurate measurement after extinction of stimuli, whereas DHEAS is more accurate and stable. Thus, this study implies that DHEAS is a stress-related hormone.

• Korean Journal of Environmental Agriculture
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• v.36 no.3
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• pp.141-146
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• 2017

BACKGROUND: Phosphorus(P) is a vital factor for rice but excess input of phosphorus fertilizer can cause environmental risk and waste of fertilizer resources. We studied to assess the change of available phosphate, P balance, critical concentration of available phosphate under a rice single system. METHODS AND RESULTS: The changes of available phosphate of paddy soil were examined from long-term fertilization experiment which was started in 1954 at the National Academy of Agricultural Science. The treatments were no phosphate fertilization(No fert., and N), phosphate fertilization(NPK, NPKC, and NPKCLS). The available phosphorus concentrations in treatments without phosphate fertilizer (No fert. and N) were decreased continuously. But, after 47 years, available phosphate content in phosphate fertilizer treatment (NPK, NPKC, and NPKCLS) reached at the highest ($245{\sim}331mg\;kg^{-1}$), showing a tendency to decrease afterward. The mean annual P field balance in these treatments (NPK, NPKC, and NPKCLS) had positive values that varied from 16.6 to $17.5kg\;ha^{-1}year^{-1}$, and ratio of residual P were increased. These showed that phosphate fertilizer in soil were converted into the form of residual phosphorus which was not easily extracted by available phosphate extractant. Also, It was estimated that the critical value of available phosphate for rice cultivation was $120mg\;kg^{-1}$ using Cate-Nelson equation. CONCLUSION: We concluded that no more phosphate fertilizer should be applied in rice single system if soil available phosphate is higher than the critical P value.

• Journal of Korean society of Dental Hygiene
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• v.2 no.2
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• pp.145-158
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• 2002

This is a section study for research of main cause and coping ways caused by stresses during the clinical experiment. It was researched by 231 students of third grade have finished clinical experiment until September though questionnaire. The methods for this study used the a stress measuring instrument thai was used by Hoa-Yun Jun and coping ways of stresses devised by Bell. We computed the frequency and the mean value by the SPSS 10.0 statistical data and we got the following result that from the experiment with t-test and the ANOVA analysis. 1. The mean value of stresses indicated rather higher states in figures 2,855 and the figures that were classified by each areas, indicated highest figures are affected by circumstances, that is 3.065. 2. As higher as the degree of satisfactions in their major, students feel stress less so, the result was not quite different between each of them (p=0.007). 3. The copping ways of stresses indicated, similar differences by using of long-term copping ways and short-term copping ways to cope with stresses(p=0.000). 4. In case of the students who failed college entrance exams and prepared for the next chance for more than one year, indicated highest figures that is 2.57 in short-term ways to cope with stresses, so it showed slightly differences between them(p=0.014). 5. According to the satisfactions of clinical experiments, there were not any statistical differences in long-term coping ways but, as smaller as the satisfactions, in that evidence of the students use short-term copping ways, it showed slightly differences between them(p=0.041). 6. According to the degree of stresses, low-stress groups use short-term coping ways more than high-stress groups, so it showed slightly differences between them(p=0.001). 7. As far as the using of long-term coping ways, the figures of between the lower stress groups and the higher stress groups indicated 2.89 and 2.97 respectably so, the figures were not so closed.

• Korean Journal of Environmental Agriculture
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• v.20 no.5
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• pp.325-329
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• 2001

Soil enzyme and microbial activities are affected by fertilizer and compost applications and can be used as sensitive indicators of ecological stability. Microbial population and soil enzymes viz., dehydrogenase, urease, acid phosphatase and aryl-sulphatase were determined in the long-term fertilizer and compost applied paddy soil. Soil samples were collected from the four treatments (control, compost, NPK and compost+NPK). Long-term NPK+compost application significantly increased activities of urease, dehydrogenase and acid phosphatase than all other treatments. The compost application enhanced activities of urease, dehydrogenase and acid phosphatase than the NPK application. However, arylsulfatase activity was not significantly different between compost and fertilizer application. The highest microbial population was recorded in the NPK+compost treatment. The compost application also resulted in higher microbial population than the NPK application. The above results indicate that ecological stability could be maintained by application of compost alone or with NPK.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.689-692
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• 2008

The purpose of this study was to analyze mechanical properties through an experiment of concrete that reinforced PET fiber, blast furnace slag and Hwangtoh. As admixture that is substitute material of cement for environmental concrete development In order to measure compressive strength, the experiment has executed to concrete, Hwangtoh concrete and a mixture specimen of Hwangtoh and PET reinforcement fiber. Also, creep and drying shrinkage experiment have executed to analyze long-term quality of specimens. Test results, compressive strength by age was not much of difference as a substitute, however, compressive strength of HTC specimen was the strongest of the three specimens. In the case of creep and drying shrinkage, long-term quality of HTC specimen was distinguished.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.4
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• pp.455-468
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• 2022

Colloid Formation and Migration (CFM) project is being carried out within the Grimsel Test Site (GTS) Phase Ⅵ. Since 2008, the Korea Atomic Energy Research Institute (KAERI) has joined CFM to investigate the behavior of colloid-facilitated radionuclide transport in a generic Underground Research Laboratory (URL). The CFM project includes a long-term in-situ test (LIT) and an in-rock bentonite erosion test (i-BET) to assess the in-situ colloid-facilitated radionuclide transport through the bentonite erosion in the natural flow field. In the LIT experiment, radionuclide-containing compacted bentonite was equipped with a triple-packer system and then positioned at the borehole in the shear zone. It was observed that colloid transport was limited owing to the low swelling pressure and low hydraulic conductivity. Therefore, a postmortem analysis is being conducted to estimate the partial migration and diffusion of radionuclides. The i-BET experiment, that focuses more on bentonite erosion, was newly designed to assess colloid formation in another flow field. The i-BET experiment started with the placement of compacted bentonite rings in the double-packer system, and the hydraulic parameters and bentonite erosion have been monitored since December 2018.

• International journal of advanced smart convergence
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• v.8 no.2
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• pp.18-29
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• 2019

In the field of Human-Computer Interaction design, persuasive design has gradually been applied to the system development and design process, especially for mobile application design. However, most mobile applications have hitherto a very short using lifecycle. Especially, design features with long-term persuasive effectiveness remain to be further researched and developed. In this study, we focused on investigating and identifying the durative persuasive design characteristics through a data mining process and evaluating the durative effectiveness through a long-term observation process. Total five hundred healthcare-related mobile applications were selected from Apple iTunes Store and a mixed method was conducted to extract the most common persuasive design characteristics. Based on the results of extraction, a representative healthcare-related mobile application was selected as experimental subject. Total one hundred and twenty participants were observed during a six-months experiment and the monitoring data of app usage of all participants was collected once a week. According to the evaluation model for behavior change identification process, participants with habit formation features were proved to have a significant long-term perception level for ten persuasive design characteristics. Further interview research was performed to investigate the participant's long-term perceptions on those characteristics for the purpose of identifying the durative persuasions. The results indicated that a long-term durative effectiveness can be observed and healthcare-related apps designed with those characteristics could have durative effectiveness. This study may contribute to the improvement of future mobile application designs in user experience and durative persuasion, as well as bringing future benefits for both mobile application developers and users.

• Journal of the Korea Society of Computer and Information
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• v.28 no.2
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• pp.201-207
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• 2023

In this paper, we propose an optimal model for mid to long-term price prediction of agricultural products using LGBM, MLP, LSTM, and GRU to compare and analyze the three strategies of the Multi-Step Time Series. The proposed model is designed to find the optimal combination between the models by selecting methods from various angles. Prior agricultural product price prediction studies have mainly adopted traditional econometric models such as ARIMA and LSTM-type models. In contrast, agricultural product price prediction studies related to Multi-Step Time Series were minimal. In this study, the experiment was conducted by dividing it into two periods according to the degree of volatility of agricultural product prices. As a result of the mid-to-long-term price prediction of three strategies, namely direct, hybrid, and multiple outputs, the hybrid approach showed relatively superior performance. This study academically and practically contributes to mid-to-long term daily price prediction by proposing an effective alternative.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.24 no.63
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• pp.13-21
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• 2001

The present study compared the two experimental methods on inquiring the image structure of odors: Presenting a stimulus is one, and not presenting a stimulus is the other. For experiment one, five odors were presented, and the subjects were instructed to evaluate the odors on 7-point scale for each of the 25 adjectives. For experiment two, no odor was presented, and the subjects were instructed to perform the pair-wise comparisons for the each pair of two adjectives on their similarities on 7-point scale. The data from the two experiments were analysed and compared using MDS(Multi-Dimensional Scaling), Correlation, Cluster Analysis. The results showed that there was no structural differences between two experimental methods in term of the Image structure of odors. But, minor disparity was found between two methods in terms of density of distribution of the adjectives. It was construed that the difference came from the difference of the memory that was used for each of the experiments; that is, short term memory for experiment one and long-term memory for experiment two.