• The Journal of the Korea Contents Association
• /
• v.13 no.12
• /
• pp.1048-1057
• /
• 2013

This study aims to evaluate the effect on the academic achievement and satisfaction of the learner's prior knowledge level and segmenting time of video lectures in an learning environment using smartphones. Depending on the level of prior knowledge, learners were divided into two groups of the upper 35% and the lower 35%. Each group was offered video lectures by a 5-min, 10-min, 15-min, and 20-min length. As a result, a high level of prior knowledge only had a positive effect on the academic achievement. With respect to the segmentation time of video lectures, 10-min, 15-min lectures were effective to the academic achievement and 15-min, 20-min lectures influenced positively the learners' satisfaction. Moreover, the interaction between the level of learners' prior knowledge and the segmentation time of video lectures only had an impact on their academic achievement. The results of the simple effect analysis conducted to examine the effect of interaction carefully show that 15-min, 20-min video lectures are more effective for the upper 35% in prior knowledge and 10-min ones are better for its' lower 35%. In a nutshell, these findings suggest that the high-prior knowledge groups could be provided with a longer video lectures, and furthermore, 5-min video lectures are not adequate in a mobile learning environment with smartphones.

• Fisheries and Aquatic Sciences
• /
• v.22 no.10
• /
• pp.23.1-23.10
• /
• 2019

Background: Taurine is a conditional essential amino acid for fish. A study was conducted to investigate the compensating effect of supplemental taurine in diets for red seabream (Pagrus major) on impaired growth performance by fish meal (FM) replacement with soybean meal (SM) at low water temperature (14.15 ± 1.95 ℃). Methods: A FM-based diet was considered as a high FM diet and three other experimental diets were formulated to replace FM with SM by 20, 35, or 50% (HFM, SM20, SM35, or SM50, respectively) without taurine and other four diets were formulated by adding 1% taurine to the diets (HFM-T, SM20-T, SM35-T, or SM50-T, respectively). Triplicate groups of fish (108.9 ± 1.58 g/fish) were distributed into 24 polyvinyl circular tanks (215 L) with 20 fish per tank and fed one of the diets to satiation for 20 weeks. Results: Growth performance and feed utilization of red seabream were significantly improved by the dietary taurine supplementation. SM20-T and SM35-T diets increased fish growth that are comparable to HFM diet. Feed intake, feed conversion ratio, and protein efficiency ratio of fish fed SM20-T and SM35-T diets were not significantly different from those of HFM group. Dietary taurine supplementation in each FM replaced group numerically increased innate immunity of the fish. Lysozyme and superoxide dismutase activities were significantly decreased in fish fed SM35, SM50, and SM50-T diets compared to those of fish fed HFM diet while they were not significantly lower in SM20, SM20-T, SM35, and SM35-T groups. Glutathione peroxidase activity was significantly lower in fish group fed SM50 diet while SM50-T group did not significantly lower compared to that of HFM group. The relative expression level of hepatic IGF-1 mRNA was improved in fish fed taurine-supplemented diets compared to their respective SM diets. Conclusions: Growth performance and feed utilization of red seabream can be accelerated or restored by 1% taurine supplementation when they are fed high level of SM up to 35% in diets during low water temperature season.

• Honam Mathematical Journal
• /
• v.35 no.3
• /
• pp.329-342
• /
• 2013

We study lightlike hypersurfaces M of a semi-Riemannian space form $\tilde{M}(c)$ with a semi-symmetric non-metric connection whose structure vector field is tangent to M. Our main result is two characterization theorems for such a lightlike hypersurface.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.5
• /
• pp.1541-1544
• /
• 2014

• Honam Mathematical Journal
• /
• v.35 no.4
• /
• pp.679-681
• /
• 2013

In this paper, we raise a question regarding existence and uniqueness of the steady-state solution of a type of Kolmogorov forward equation. We prove that the question has a positive answer for trivial vector fields, and also provide examples which show that the compactness assumption is necessary.

• Proceedings of the Korean Society of Sericultural Science Conference
• /
• 2004.10a
• /
• pp.35-35
• /
• 2004

• Journal of the Chungcheong Mathematical Society
• /
• v.35 no.3
• /
• pp.197-204
• /
• 2022

In this article, we define a modified Koszul complex, which we call a quantized Koszul complex, on a quantum space ring, and we also prove that it is an acyclic complex.

• Journal of the Chungcheong Mathematical Society
• /
• v.35 no.1
• /
• pp.13-23
• /
• 2022

Let G be a semialgebraic group not necessarily compact. Let M be a proper semialgebraic G-set whose orbit space has a semialgebraic structure. In this paper, we prove the embeddability of M into a G-representation space when G is linear.

• Journal of Convergence Society for SMB
• /
• v.6 no.4
• /
• pp.25-30
• /
• 2016

This paper presents on the development of a compact anti-lost device requested recently. The proposed device consists of the master and slave modules based on Bluetooth4.1 technology. To implement a low-power characteristic, an algorithm has been also developed. The transmitting and receiving circuits are designed by using BoT CLE110 module supporting Bluetooth 4.1. The ATmega 328P-AU was used for the control and LP3874EMP was used as a linear regulator. Power consumption of the fabricated product in operating mode is only 10mAh and 35mAh for MCU operating state. Alarm operation distance is $10m{\pm}30%$, the effective radiated power is less than 10mW, the frequency band is designed to operate in the Bluetooth band with 26MHz bandwidth. And algorithms have been developed to extend the battery life. The size of the product was obtained as $45{\times}45{\times}15mm$ for master and $35{\times}35{\times}10mm$ fr slave. After the optimization process, it is expected to be commercialized as a wristwatch for anti-lost device.

• Fire Science and Engineering
• /
• v.18 no.4
• /
• pp.86-92
• /
• 2004

We tested five specimens of each species at each of five constant external heat flux levels (10, 15, 20, 25. and 35㎾/㎡). An Cone heater was used to expose the wood specimens to the heat flux. The 100-by 100-by 50-㎜ specimens were of four species: Redwood, White oak, Douglas fir, Maple. In result of test, charring of wood exposed to a constant external heat flux can be considered a linear with function of time. As compared with the charring rates Redwood is most rapidly, but on the other hand Douglas fir is most slowly. When the external heat flux is 35㎾/㎡, the charring rate is rapidly about twice then 10㎾/㎡. Using the Equation (2), the estimates for u were 1.02, 1.16, 1.23, 1.32, and 1.44 for the 10, 15, 20, 25, and 35 kw/m2 constant external exposure levels, respectively.