• Korean Journal of Organic Agriculture
• /
• 제28권4호
• /
• pp.605-614
• /
• 2020

This study was conducted to investigate the effects of TMR on in vitro rumen fermentation and methane production of goat with different forage sources. The experiment was arranged 4×2 factorial design. The different forage sources were rice straw (RS), Italian rye grass (IR), timothy (TI) and alfalfa (AL), respectively. There were two different forage : concentrate ratios such as 20:80 (20) and 50:50 (50), respectively. Therefore, totally 8 treatments were used: 1) RS20, 2) RS50, 3) IR20, 4) IR50, 5) TI20, 6) TI50, 7) AL20, and 8) AL50, respectively. The rumen fluid of goat was collected from the slaughterhouse. For fermentation parameters, ruminal pH, total gas, methane, hydrogen, ammonia nitrogen, and volatile fatty acid were determined. The pH values were within an optimal range across all treatments. Total gas productions at TI20 and AL50 were significantly greater than others (p<0.05). Methane production was significantly lower in TI and AL compared with other treatments (p<0.05). The relatively high dietary NDF content in treatments showed significantly lower methane production (p<0.05). Significant alterations treatments were detected at ammonia nitrogen concentration according to the ratio of forage : concentrate (p<0.05). AL treatment showed greater total volatile fatty acid production compared with other treatments (p<0.05). Therefore, the present study suggests that both Timothy and Alfalfa could be recommendable forage sources for goat based on results with volatile fatty acid as an energy source and methane as an index for energy loss and environmental issues. Also, the 50:50 (forage : concentrate) ratio would prefer to 20:80.

• The Journal of Korean Association of Computer Education
• /
• 제22권3호
• /
• pp.55-65
• /
• 2019

In programming language learning system of flip learning methods, the evaluation of cyber lectures generally proceeds from online to multiple choice questions. In this case, the questions are randomly extracted from the question bank and given to individual learners. In order for these evaluation results to be reflected in the grades, the equity of the examination question is more important than anything else. Especially in the programming language subject, the degree of difficulty that learners think can be different depending on the type of problem. In this paper, we classify the types of multiple-choice problems into two categories, and manage the difficulty level by each type. And we propose a question selection algorithm that considers both difficulty level and type of question. Considering the characteristics of the programming language, experimental results show that the proposed algorithm is more efficient and fair than the conventional method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 한국정보통신학회 2014년도 추계학술대회
• /
• pp.569-572
• /
• 2014

This paper presents a CMOS switched-capacitor interface circuit for MEMS capacitive sensors. It consist of a capacitance to voltage converter(CVC), a second-order ${\Sigma}{\Delta}$ modulator, and a comparator. A bias circuit is also designed to supply constant bias voltages and currents. This circuit employes the correlated-double-sampling(CDS) and chopper-stabilization(CHS) techniques to reduce low-frequency noise and offset. The designed CVC has a sensitivity of 20.53mV/fF and linearity errors less than 0.036%. The duty cycle of the designed ${\Sigma}{\Delta}$ modulator output increases about 5% as the input voltage amplitude increases by 100mV. The designed interface circuit shows linearity errors less than 0.13%, and the current consumption is 0.73mA. The proposed circuit is designed in a 0.35um CMOS process with a supply voltage of 3.3V. The size of the designed chip including PADs is $1117um{\times}983um$.

• Journal of the korean academy of Pediatric Dentistry
• /
• 제46권2호
• /
• pp.183-189
• /
• 2019

The purpose of this study was to investigate the changes of the position of the mental foramen according to age by using panorama of children with mixed and early permanent dentition. 180 panorama of 6 to 13-year-old boys and girls were analyzed and PiView(Infinitt, Korea) program was used. The horizontal position of the mental foramen was evaluated by the relative position of the teeth. The vertical position of the mental foramen was evaluated by the ratios between the distance from the center of the mental foramen to the inferior border of the mandible and the distance from to the alveolar crest to the inferior border of the mandible. The mental foramen was horizontally located in the anterior aspect of the second primary molar(premolar), and vertically slight below the half of mandibular body. As the age increased, it moved to the posterior and the downward and showed a significant correlation with age.

• Food Engineering Progress
• /
• 제23권1호
• /
• pp.69-75
• /
• 2019

This study investigated the effects of blanching conditions on the quality characteristics of burdock, lotus root, and garlic scape. The selected plants were blanched at varying temperatures (70-100℃) for 1-5 min, and moisture content, shear force, color, and total microbial count were analyzed. Burdock exhibited browning discoloration when it was blanched at a relatively low temperature (70-80℃). In addition, thermal tenderization of burdock was not evident in the blanching conditions adopted in this study. Blanching affected the tenderness and moisture content of lotus root without deteriorative discoloration. In particular, low temperature blanching (80℃) was favorable to blanching lotus root. Alternately, thermal tenderization of garlic scape was possible by blanching at 80-100℃ for 3-5 min, while discoloration of the blanched garlic scape dominated at high-temperature blanching (100℃). Consequently, the result indicated that low temperature for a long time (80℃ and 3-5 min) provided a better blanching condition for lotus root and garlic scape than high temperature applied at a short time (100℃ and 1-3 min).

• Journal of Korea Society of Industrial Information Systems
• /
• 제27권2호
• /
• pp.11-24
• /
• 2022

For the questions asked for LMS-based online evaluation the professor directly set exam questions, or use the automatic question-taking method according to the level of difficulty using the question bank divided by category. Among them, it is important to manage the difficulty of questions in an objective and efficient way, above all, in the automatic question-taking method according to difficulty. Because the questions presented to the evaluators may be different. In this paper, we propose an difficulty re-adjustment algorithm that considers not only the correct rate of a problem but also the time taken to solve the problem. For this, a logistic regression classification algorithm was used of machine learning, and a reference threshold was set based on the predicted probability value of the learning model and used to readjust the difficulty of each item. As a result, it was confirmed that there were many changes in the difficulty of each item that depended only on the existing correct rate. Also, as a result of performing group evaluation using the adjustment difficulty problem, it was confirmed that the average score improved in most groups compared to the difficulty problem based on the percentage of correct answers.

• Journal of the Korean School Mathematics Society
• /
• 제24권4호
• /
• pp.349-367
• /
• 2021

In this study, 85 studies on probability education from 2000 to 2020 were analyzed by publishing year, journals, research subjects, and research topics. Especially, fundamental probabilistic ideas presented by Batanero et al.(2016) were applied to examine which topics were dominant in domestic probability education research. As a result, it was found that there has been a few research in probability education in Korea during the past 20 years, and the number of human subject studies was slightly more than the number of non-human subject studies. In addition, the analysis of research topics according to the fundamental probabilistic ideas showed that two topics, conditional probability and independence and combinatorial enumeration and counting, were dominant in domestic probability education research. However, while both conditional probability and independence and combinatorial enumeration and counting are introduced to young children using intuitive manners in international probability education research, subjects related to these topics were primarily high school students and pre and in-service teachers. Based on the results of this study, the implications for the goal and the direction of future probability education research were discussed.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• 제50권10호
• /
• pp.709-716
• /
• 2022

In this paper the Gamma guidance law, which was used for IUS (Inertial Upper Stage), is applied for solid-motor guidance of a upper stage of a satellite launch vehicle. The RCS (Reaction Control System), which activates after burnout of the upper stage, is employed for the convergence of the guidance algorithm and compensation of velocity errors induced by the solid motor. The algorithm is also simplified by replacing the time-consuming numerical integration process to predict final vehicle states with Keplerian trajectories. The performance of the algorithm is evaluated by conducting 3-DOF computer simulations for off-nominal flight conditions. The numerical results show that Gamma guidance can reduce the orbit injection accuracy in comparison with that obtained by applying open-loop commands.

• Education of Primary School Mathematics
• /
• 제25권4호
• /
• pp.361-375
• /
• 2022

In this study, the vocabularies in elementary mathematics textbooks for grade 1-2 were analyzed according to 9-degree of semantic system. Also, the types of vocabulary were analyzed using general academic words, mathematics specific concept words, and mathematics general concept words. As a result, percentages of 1-degree and 2-degree vocabulary was the most in both grade 1 and 2 mathematics textbooks. It also shows that some of general academic words were 3-degree vocabulary and some of mathematics specific concept words were either unregistered or 1-degree vocabulary. In particular, general academic words, which are 3-degree vocabulary, may be unfamiliar to 1^st and 2^nd grade students. Therefore, students should be given the opportunity to guess and understand the contextual meaning of general academic words from the given contexts in textbooks. The frequency of use of mathematics general concept words in grade 2 textbook increased significantly compared to grade 1 textbook. Since mathematics general concept words are academic and technical vocabulary they should be taught explicitly. Based on the results of this study, implications for vocabulary instruction in mathematics textbooks were discussed.

• Journal of Urban Science
• /
• 제11권2호
• /
• pp.45-54
• /
• 2022

Recently, regulations on automobile exhaust gas emission are being strengthened. Accordingly, automobile exhaust gas emissions are expected to decrease and continue to decrease. On the other hand, many countries do not yet consider the emission of non-exhaust air pollutants from automobiles as important. Automobile non-exhaust substances are classified into three categories: tire dust emissions, brake wear emissions, and road scattering dust. In particular, in the case of tire dust, research results exist that pollutant emissions increase as the weight of a vehicle increases. Since the weight of trucks varies according to the load and the load along the axles is also different, it can be expected that the emission of PM10 from the tire dust will be different depending on the loading method. Therefore, this study was conducted on the amount of PM10 generated in tire dust considering the axle load of the truck according to the loading method. However, it was confirmed that the total amount of PM10 was less than that all loads are loaded in the front or rear when the load was evenly distributed in the front and rear of the cargo compartment. In particular, if the load is distributed evenly in the front and back of the cargo compartment and the load in the front part is divided into 2 to 6 and loaded, as the number of divided loading increases the amount of PM10 generated decreases. And when the load is divided into 6 pieces, the total amount of PM10 generated is 0.3952g, the minimum value. If the load is divided into 6 or more and loaded evenly, the total PM10 generated continuously increases and converges to about 0.3964g.