• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.9
• /
• pp.4602-4609
• /
• 2013

In summer and winter, the difference between the temperature during the day and that during the night is high, which leads to various problems during concrete placement, such as cracks and defects in the concrete as well as low durability and strength. Although nuclear power plant concrete is widely used for placement in all seasons, particular attention must be paid to its quality during the summer. Therefore, we evaluated the effects of a cooling method for mixing water, which is a commonly used hot weather precooling method, and the use of a retarder, on the characteristics of Nuclear Power Plant concrete. In the cooling method for mixing water, cold water at 5 was used, with 50% of the water content consisting of ice flakes. The effects of using a retarder were evaluated by reviewing the characteristics of the cement at the unset stage and after hardening. To evaluate the characteristics of the unset cement, we measured the slump, air volumes, setting times, and pressure strengths after hardening. Furthermore, we measured the heat of hydration at different temperatures; the loss of heat was minimized using insulation. Both the slump time and the complete ageing time of the air volume were found to be 120 min at $20^{\circ}C$ and 40 min at $40^{\circ}C$. In the case when the cooling method for mixing water was used and in the case when a retarder was used, the initial and final sets by penetration resistance were delayed, and the delay decreased with increasing air temperature. For the heat of hydration, the cooling method for mixing water not only lowered the maximum temperature but also delayed its attainment. However, the use of a retarder had no effect on the maximum temperature. Moreover, in the early ages (e.g., 3 and 7 days), the pressure strength of the concrete was lower than that of plain cement. However, the strength of 28-day concrete met the standard construction specifications.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.3
• /
• pp.47-56
• /
• 2020

In this study, three levels of W/B(Water to Binder) ratio (0.37, 0.42, 0.47) and substitution ratio of GGBFS (Ground Granulated Blast Furnace Slag) rate (0 %, 30 %, 50 %) were considered to perform RCPT (Rapid Chloride Diffusion Test) at the 1,095 aged day. Accelerated chloride diffusion coefficient and passed charge of each concrete mixture were assessed according to Tang's method and ASTM C 1202, and improving behaviors of durability performance with increasing aged days are analyzed based on the test results of previous aged days from the preceding study. As the age of concrete increases, the passed charge and diffusion coefficient have been significantly reduced, and especially the concrete specimens containing GGBFS showed a significantly more reduction than OPC(Ordinary Portland Cement) concrete specimen by latent hydraulic activity. In the case of OPC concrete's results of passed charge, at the 1,095 days, two of them were still in the "Moderate" class. So, if only OPC is used as the binder of concrete, the resistance performance for chloride attack is weak. In this study, the time-parameters (m) were derived based on the results of the accelerated chloride diffusion coefficient, and the deterministic and probabilistic analysis for service life were performed by assuming the design variable as a probability function. For probabilistic service life analysis, durability failure probabilities were calculated using Monte Carlo Simulation (MCS) to evaluate service life. The service life of probabilistic method were lower than that of deterministic method, since the target value of PDF (Probability of Durability Failure) was set very low at 10 %. If the target value of PDF suitable for the purpose of using structure can be set and proper variability can be considered for each design variable, it is believed that more economical durability design can be made.

• Korean Journal of Soil Science and Fertilizer
• /
• v.21 no.3
• /
• pp.272-279
• /
• 1988

A pot experiment was conducted to define the effect of various soil phosphorus fractions for soybean yield and the relations of between various soil phosphorus fraction and each other in 11 upland soils with different capacities of phosphorus fixation and physico-chemical properties of soils. The effect of phosphorus fertilization was high in soils with high capacities of phosphorus fixation and low available phosphorus, and soybean yield was showed significant relationship with available phosphorus and inorganic soil phosphorus fractions. Fractional recovery of added phosphorus in soils were showed various range of 2.5-91.7%, and mean value of soils was 48.5%. In the relationships among the soybean yield, plant phosphorus content, phosphorus uptake and available phosphorus, inoganic phosphorus at flowering stage, soybean yield were showed significant relationship with available phosphorus content, phosphorus uptake were all showed significant correlation without Fe-P, but Fe-P was showed except Jeju soil. Al-P/Fe-P ratio was increased by phosphorus fertilization in soils at flowering stage, and in the relationships between Al-P/Fe-P ratio and soybean yield, phosphorus uptake, soil and plant phosphorus were showed high significant correlation, but Fe-P was not showed at flowering stage. P sorbed by soils from P 20ppm solution was decreased by phosphorus fertilization, and then decreasing rate was higher in soils with low capacity of phosphorus fixation then high phosphorus fixing soils. Also P sorbed was showed negatively high significant correlation with available phosphorus, plant phosphorus, phosphorus uptake and soil inorganic phosphours except Fe-P, and soybean yield was not showed.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.23 no.3
• /
• pp.159-168
• /
• 2003

This pot experiment was conducted in order to find out the effects of boron application($B_{0}$ /; control, $B_1$; 0.2, $B_2$; 2.0,$ B_3$; 6.0, $B_4$; 15.0 B me/pot) on the forage performance of pure and mixed cultures of orchardgrass and white clover. The 2nd part was concerned with the changes in the forage yields and concurrence index. The results obtained are summarized as follows: 1. The optimum boron application($B_2$) generally resulted in the increase of both forage yields, but the effects of boron application on them were different according to the forage species, whether it was a pure or mixed cultures, additional fertilization, and cutting order. The effects of boron application on the forage productivity were more obvious in white clover than in orchardgrass. 2. Owing to the decline of white clover as affected by the application of additional fertilizers, especially N, in the grass-clover mixed cultures, the effects of boron application on the white clover yields showed a numerical inferiority compared with the pure culture. It was recognized that the yield increase and botanical composition of white clover in grass-clover mixed cultures could be regulated by the application of additional fertilizers and boron. 3. The toxic boron application($B_3$ and $B_4$) resulted in a decreased yield of both forages. The yield change of orchardgrass tended to be similar between pure and mixed cultures, whereas it of white clover tended to be more negative in mixed than in pure cultures. 4. With the application of additional fertilizers, especially N, the botanical composition and concurrence index in grass-clover mixed cultures were relatively increased in orchardgrass, and decreased in white clover. The botanical composition of orchardgrass increased from 55% to 75%, whereas it of white clover decreased from 45% in the first half cutting to 25% in the second half cutting, respectively.

• The Korean Journal of Food And Nutrition
• /
• v.28 no.2
• /
• pp.302-312
• /
• 2015

This study was conducted to evaluate the effects of constitutional diets in comparison with general low calorie diets in obese women. The subjects were 52 adult obese women that participated in a calorie restriction diet program (control group, n=16) or a constitutional diet program (experimental group, n=36) for 8 weeks. The subjects in the experimental group were classified as negative (Yin) or positive (Yang) constitution. The obesity management program focused on the calorie restriction diet (300~400 kcal reduction per day) for the control group, whereas, for a constitutional diet without calorie restrictions was allowed for the experimental group. Daily intakes of nutrient and food were assessed using a 24 hr recall method. Body measurements and blood biochemical parameters were measured at baseline and after 8 weeks. After the intervention, weight, body fat, BMI, waist circumference and hip circumference decreased significantly in both the control and experimental group. Energy intake increased from 1,679.6 kcal to 1,810.6 kcal along with significant increase in protein, carbohydrate, fiber, calcium, phosphorus, iron, zinc, vitamin A, vitamin $B_1$, vitamin $B_2$, niacin and vitamin C in the experimental group. Calcium intake increased from 54.0% to 72.4% of DRI in the experimental group. Hemoglobin concentrations were significantly decreased in the control group, but were increased in the experimental group. In addition, blood glucose, serum total cholesterol and triglyceride were significantly decreased in the experimental group. In conclusion, consumption of a constitutional diet without calorie restrictions for 8 weeks was effective for weight reduction with improvement of blood glucose, serum cholesterol and triglyceride.

• Journal of The Korean Ophthalmological Society
• /
• v.59 no.11
• /
• pp.1039-1048
• /
• 2018

Purpose: To evaluate the effects of anti-vascular endothelial growth factor (VEGF) treatment on the healthcare-related finances of patients with age-related macular degeneration. Methods: Changes in health care financing due to newly introduced benefit standards were predicted over the coming 5-year period (2018-2022). We also analyzed the financial impact of scenarios in which agents similar to anti-VEGF, such as the over-licensed drug bevacizumab, were introduced. For this purpose, the future number of patients receiving anti-VEGF treatments was estimated for various scenarios based on National Health Insurance Corporation claims data followed by an estimate of the financial burden. Results: In the case of age-related macular degeneration, the current standard of care (14 times in a lifetime) was maintained in scenario 1. In 2018, the insurance budget for the coming 5-year period was estimated at approximately 440.3 billion won. The insurance cost for that period was estimated at approximately 560.1 billion won under the revised standard of December 2017 (scenario 2). For scenarios wherein, after 2020, similar treatments (scenario 3) and bevacizumab (scenario 4) were introduced, the estimated health insurance costs were 521 billion won and 419.7 billion won, respectively. Conclusions: Health insurance costs are projected to increase substantially due to the elimination of the 14 time pay standard; however, the actual budget will only moderately increase, due to new limitations of visual acuity ${\leq}0.1$ or in case of scarring/atrophic lesions. Clinically similar agents and bevacizumab could be considered as alternatives to anti-VEGF treatment for age-related macular degeneration.

• Korean Journal of Remote Sensing
• /
• v.14 no.3
• /
• pp.213-222
• /
• 1998

Electro-Optical Camera(EOC) is the main payload of the KOrea Multi-Purpose SATellite(KOMPSAT) with the mission of cartography to build up a digital map of Korean territory including a Digital Terrain Elevation Map(DTEM). This instalment which comprises EOC Sensor Assembly and EOC Electronics Assembly produces the panchromatic images of 6.6 m GSD with a swath wider than 17 km by push-broom scanning and spacecraft body pointing in a visible range of wavelength, 510~730 nm. The high resolution panchromatic image is to be collected for 2 minutes during 98 minutes of orbit cycle covering about 800 km along ground track, over the mission lifetime of 3 years with the functions of programmable gain/offset and on-board image data storage. The image of 8 bit digitization, which is collected by a full reflective type F8.3 triplet without obscuration, is to be transmitted to Ground Station at a rate less than 25 Mbps. EOC was elaborated to have the performance which meets or surpasses its requirements of design phase. The spectral response, the modulation transfer function, and the uniformity of all the 2592 pixel of CCD of EOC are illustrated as they were measured for the convenience of end-user. The spectral response was measured with respect to each gain setup of EOC and this is expected to give the capability of generating more accurate panchromatic image to the users of EOC data. The modulation transfer function of EOC was measured as greater than 16 % at Nyquist frequency over the entire field of view, which exceeds its requirement of larger than 10 %. The uniformity that shows the relative response of each pixel of CCD was measured at every pixel of the Focal Plane Array of EOC and is illustrated for the data processing.

• Geophysics and Geophysical Exploration
• /
• v.8 no.1
• /
• pp.50-58
• /
• 2005

Recently, the imaging of geological structures beneath water-covered areas has been in great demand because of numerous tunnel and bridge construction projects on river or lake sites. An electrical resistivity survey can be effective in such a situation because it provides a subsurface image of faults or weak zones beneath the water layer. Even though conventional resistivity surveys in water-covered areas, in which electrodes are installed on the water bottom, do give high-resolution subsurface images, much time and effort is required to install electrodes. Therefore, an easier and more convenient method is sought to find the strike direction of the main zones of weakness, especially for reconnaissance surveys. In this paper, we investigate the applicability of the streamer resistivity survey method, which uses electrodes in a streamer cable towed by ship or boat, for delineating a fault zone. We do this through numerical experiments with models of water-covered areas. We demonstrate that the fault zone can be imaged, not only by installing electrodes on the water bottom, but also by using floating electrodes, when the depth of water is less than twice the electrode spacing. In addition, we compare the signal-to-noise ratio and resolving power of four kinds of electrode arrays that can be adapted to the streamer resistivity method. Following this numerical study, we carried out both conventional and streamer resistivity surveys for the planned tunnel construction site located at the Han River in Seoul, Korea. To obtain high-resolution resistivity images we used the conventional method, and installed electrodes on the water bottom along the planned route of the tunnel beneath the river. Applying a two-dimensional inversion scheme to the measured data, we found three distinctive low-resistivity anomalies, which we interpreted as associated with fault zones. To determine the strike direction of these three fault zones, we used the quick and convenient streamer resistivity.

• Journal of Sericultural and Entomological Science
• /
• v.50 no.2
• /
• pp.63-70
• /
• 2012

This study was conducted to investigated the distribution, ecological character and life cycle of Black Soldier Fly(BSF), Hermetia illucens, to determine effects of BSF on composing ability to the livestock feces. The distribution of BSF was defined in all parts of the country in Korea. Its main habitat was found to be areas near cattle sheds, feces sheds, living waste dump grounds, and food waste dump grounds. Excellent species of the bio-conversion using the livestock feces were selected out of two kinds of solider flies(Hermetia illucens and Ptecticus tenebrifer). And effects of BSF on composing ability to the livestock feces were pig feces 0.5 g, cattle feces 0.43 g and chicken feces 0.3 g per a larvae of BSF. In the examination of the ability of BSF to decompose food waste, volume of the livestock feces decreased by weight pig feces 77, cattle feces 83.62 and chicken feces 80%. Observed characteristics of BSF larvae and pupae stage were by developmental stage may be summarized as follows: size and length of larvae and pupae of BSF were higher than in pig feces and mixed sawdust treatments. In order to develop artificial indoor rearing techniques, The pupation and emergence rate were not visible the difference but important factor of the mating and egg-laying was a sun light. And it was visible the difference in mating ratio. Mating rate of H. illucens by seasonal change was the highest from May to July. Mating mostly occurred between 10 : 00 and 12 : 00 during which light intensity is high. As the egg-laying medium for artificial egg collection, calf feed and food waste were most effective. The ratio of egg-laying medium is waste food : sawdust(1 : 1) in volume. For egg-laying materials, flower foam and wood with holes were used; holes sized 3 ~ 5 mm in diameter, 7 ~ 10 mm in depth were most preferred for egg-laying.

• The Journal of Society for e-Business Studies
• /
• v.26 no.3
• /
• pp.33-53
• /
• 2021

In the crossroads of social change caused by the spread of the Fourth Industrial Revolution and the prolonged COVID-19, the Korean government announced the Digital New Deal policy on July 14, 2020. The Digital New Deal policy's primary goal is to create new businesses by accelerating digital transformation in the public sector and industries around data, networks, and artificial intelligence technologies. However, in a rapidly changing social environment, information asymmetry of the future benefits of technology can cause differences in the public's ability to analyze the direction and effectiveness of policies, resulting in uncertainty about the practical effects of policies. On the other hand, the media leads the formation of discourse through communicators' role to disseminate government policies to the public and provides knowledge about specific issues through the news. In other words, as the media coverage of a particular policy increases, the issue concentration increases, which also affects public decision-making. Therefore, the purpose of this study is to verify the dynamic relationship between the media coverage and the stock market on the Korean government's digital New Deal policy using Granger causality, impulse response functions, and variance decomposition analysis. To this end, the daily stock turnover ratio, daily price-earnings ratio, and EWMA volatility of digital technology-based companies related to the digital new deal policy among KOSDAQ listed companies were set as variables. As a result, keyword search volume, daily stock turnover ratio, EWMA volatility have a bi-directional Granger causal relationship with media coverage. And an increase in media coverage has a high impact on keyword search volume on digital new deal policies. Also, the impulse response analysis on media coverage showed a sharp drop in EWMA volatility. The influence gradually increased over time and played a role in mitigating stock market volatility. Based on this study's findings, the amount of media coverage of digital new deals policy has a significant dynamic relationship with the stock market.