• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.36 no.5
• /
• pp.505-512
• /
• 2023

This study investigated crystal structures, microstructures, and electric-field-induced strain (EFIS) properties of Bi-based lead-free ferroelectric/relaxor composites. Bi_1/2Na_0.82K_0.18)_1/2TiO₃ (BNKT) as a ferroelectric material and 0.78Bi_1/2(Na_0.78K_0.22)_1/2TiO₃-0.02LaFeO₃ (BNKT2LF) as a relaxor material were synthesized using a conventional solid-state reaction method, and the resulting BNKT2LF powders were subjected to high-energy ball milling (HEBM) after calcination. As a result, HEBM proved a larger average grain size of sintered samples compared to conventional ball milling (CBM). In addition, the increased sintering time led to grain growth. Furthermore, HEBM treatment and sintering time demonstrated a significant effect on EFIS of BNKT/BNKT2LF composites. At 6 kV/mm, 0.35% of the maximum strain (S_max) was observed in the HEBM sample sintered for 12 h. The unipolar strain curves of CBM samples were almost linear, indicating almost no phase transitions, while HEBM samples displayed phase transitions at 5~6 kV/mm for all sintering time levels, showing the highest S_max/E_max value of 700 pm/V. These results indicated that HEBM treatment with a long sintering time might significantly enhance the electromechanical strain properties of BNT-based ceramics.

• Journal of Powder Materials
• /
• v.30 no.3
• /
• pp.242-248
• /
• 2023

The Ag/WC electrical contacts were prepared via powder metallurgy using 60 wt% Ag, 40 wt% WC, and small amounts of Co₃O₄ with varying WC particle sizes. After the fabrication of the contact materials, microstructure observations confirmed that WC-1 had an average grain size (AGS) of 0.27 ㎛, and WC-2 had an AGS of 0.35 ㎛. The Ag matrix in WC-1 formed fine grains, whereas a significantly larger and continuous growth of the Ag matrix was observed in WC-2. This indicates the different flow behaviors of liquid Ag during the sintering process owing to the different WC sizes. The electrical conductivities of WC-1 and WC-2 were 47.8% and 60.4%, respectively, and had a significant influence on the Ag matrix. In particular, WC-2 exhibited extremely high electrical conductivity owing to its large and continuous Ag-grain matrix. The yield strengths of WC-1 and WC-2 after compression tests were 349.9 MPa and 280.7 MPa, respectively. The high yield strength of WC-1 can be attributed to the Hall-Petch effect, whereas the low yield strength of WC-2 can be explained by the high fraction of high-angle boundaries (HAB) between the WC grains. Furthermore, the relationships between the microstructure, electrical/mechanical properties, and deformation mechanisms were evaluated.

• Journal of the Korean Society of Food Culture
• /
• v.23 no.6
• /
• pp.779-792
• /
• 2008

The consumption of a wide variety of food groups is considered one of the key components of nutritional adequacy. The 2005 Dietary Guidelines for Koreans includes the consumption of a variety of foods from diverse food groups as a component of a normal diet. A survey was conducted to evaluate the relationship between the dietary diversity of food groups and nutrient intake in elderly patients (age 65 and above) at a rural area in Korea (Inje). 296 subjects (111 male and 185 female) were probed in a 3 day 24-recall dietary survey. Subjects were grouped according to food group intake frequency, based on six food groups (grain, meat/fish/legume/egg, vegetable, fat/oil, dairy, fruit). Nutritional quality was evaluated according to the numbers of nutrients under EAR (Estimated Average Requirements), and MAR (mean adequacy ratios). The frequency of elderly subjects consuming a meat/fish/legumes/egg food group less than once per day was 29.4%. The frequency of elderly subjects consuming fat/oil food group less than once per day was 65.8%. The percentage of subjects who did not eat dairy food was 88.8%, and that of subjects who did not eat fruit was 57.5%. A stepwise multiple regression analysis was used to develop models relating nutritional quality to possible food group intake frequency factors. Using the number of nutrients under EAR as a dependent variable, the meat/fish/legume/egg food group intake frequency explained 9.9% of variance, followed by the grain group, fat/oil group, dairy group, and vegetable and fruit group (Model $R^2$=0.260). For mean nutrient adequacy ratio as a dependent variable, the model $R^2$ was 0.326. The results of this study suggest that a highly varied diet in elderly might be associated with better nutritional quality, as assessed by nutrient intake. Accordingly, dietary guidelines should take into consideration nutritional characteristics in order to improve intake from all major food groups and to provide a variety of foods in the diet.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.183-183
• /
• 2022

This study was aimed to investigate the content of avenanthramides(AVNs) and other phenolic compounds in the grains of a naked oat cultivar, Daeyang, which were seeded in the fall and spring, and examine the effects of alcohol extracts from the grains on natural killer(NK) cell activity in vitro. The content of AVN-A, AVN-B, and AVN-C in the spring-seeded oat grains was 2.2 folds higher than the fall-seeded oat grains on average. Among these AVNs, the content of AVN-C was 1.9-folds higher in the spring-seeded oat grains(66.1㎍/g), comparing to the content in the fall-seeded oat grains(34.8㎍/g). The content of other phenolic compounds, such as phenolic acids and flavonoids in the spring-seeded oat grains was 1.1~4.7-folds higher than the fall-seeded oat grains. In particular, sinapinic acid was the most abundant phenolic acid in the spring-seeded oat grains(50.0㎍/g) and its content was 2.4-folds higher than its content in the fall-seed oat grains. Furthermore, NK cell activity in vitro treated with the spring-seeded oat grain extracts was 158%, and it was 18%p higher than NK cell activity treated with the extracts from the fall-seeded oat grain extracts. Our finding suggest that the bioactive properties of naked oat grains would be enhanced by spring seeding.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.252-252
• /
• 2022

Genotype-by-environment interaction (GEI) refers to the comparative response of genotypes to different environments conditions. Thus, understanding GEI is a fundamental component for selecting superior genotypes for breeding programs. The significance of utilizing early maturing cultivars not only provides flexibility in planting dates, but also serves as an effective strategy to reduce methane emission from the paddy fields. In this study, we conducted multi-environment trials (METs) to evaluate yield-related traits such as culm length, panicle length, panicle number, spikelet per plant, and thousand grain weight. A total of eighty-one Korean commercial rice cultivars categorized as early maturing cultivars, were cultivated in three regions, two planting seasons for two years. The genotype main effect plus genotype-by-environment interaction (GGE) biplot analysis of yield-related traits and grain yield explained 70.02-91.24% of genotype plus GEI variation, and exhibited various patterns of mega-environment delineation, discriminating ability, representativeness, and genotype rankings across the planting seasons and environments. Moreover, simultaneous selection using weighted average of absolute scores from the singular value decomposition (WAASB) and multi-trait stability index (MTSI) revealed six highly recommended genotypes with high stability and crop productivity. The winning genotypes under specific environment can be utilized as useful genetic materials to develop regional specialty cultivars, and recommended genotypes can be used as elite climate-resilient parents to improve yield-potential and reduce methane emission as part to accomplish carbon-neutrality.

• Progress in Superconductivity and Cryogenics
• /
• v.6 no.1
• /
• pp.12-17
• /
• 2004

High critical current density. $J_c$ over $1MA/cm^2$ at 77 K in a self field was successfully achieved from the YBCO film prepared on (100) $SrTiO_3$ single-crystal substrates by the TFA-MOD process. Unlike a normal TFA-MOD process, we prepared the TFA precursor solution by dissolving YBCO powder into the trifluoroacetic acid. A significant amount of the second phases, including $BaF_2$, was observed in the films fired at $700-725^{\circ}C$ for 2 h under $P(O_2)=10^{-3}$ atm and $P(H_2O)=4.2%$, most probably due to an insufficient reaction time, and hence $T_c$ was greatly degraded. However the films fired at $750-800^{\circ}C$ for 2 h were composed of strongly c-axis oriented YBCO grams without any second phases. and exhibited the $T_c$ values of 89.5 ~ 91 K with a sharp transition. With increasing the firing temperature from 750 to $800^{\circ}C$ average grain size of YBCO was increased and grain connectivity was enhanced. The highest $J_c$ value of $1.1MA/cm^2$ was obtained from the YBCO film fired at $800^{\circ}C$.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.44 no.3
• /
• pp.179-184
• /
• 2024

Corn is essential for both humans and animals. The crop is the third most important food crop after rice and wheat. A rise in farming is resulting in a lack of self-sufficiency of high quality forages. Therefore, corn cultivars in Korea must be optimized to increase productivity and yield. A study was conducted in Pyeongchang, South Korea between 2021-2022 to evaluate the characteristics and productivity of three corn cultivars: Kwangpyeongok, AGR 41, and Nero IT. Different varieties of corn were sown in Pyeongchang on April 29 and April 27 of 2021 and 2022, respectively. The productivity and characteristics of the cultivars Kwangpyeongok, AGR 41, and Nero IT were evaluated during the yellowing ripening stage. The characteristics included the leaves, stems, grain, and stover content. Across different corn cultivars, there was no significant difference in stem height, diameter, forage or grain quantity based on an average of two years. Yet, significant differences were noted in the stem heights of all cultivars between 2021 and 2022 (p<0.05). There was a significant difference in the diameters of Kwangpyeongok and Nero IT between 2021 and 2022. A significant difference in forage yield was observed for Nero IT between 2021 and 2022. The yield of grains and forages was higher in 2021 than in 2022, which could be attributed to temperature and precipitation variations. We can conclude from these data that all cultivars in Pyeongchang showed significant productivity and yield, which could be useful to produce nutrient rich silage for livestock.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.323-323
• /
• 2017

In many sub-Saharan African countries, boosting rice production is a pressing food security issue. To contribute to the increase in rice production, we have developed lines of NERICA 1 introgressed with the gene for spikelet number, Gn1a, and the gene for primary rachis-branch number, WFP by cross breeding. The performance of rice lines introgressed with the genes for yield related traits can be affected by cultivation environment and management. Thus, in this study, we aimed to evaluate the lines of NERICA 1 introgressed with Gn1a or/and WFP for yield and yield components under different nitrogen fertilization conditions in Kenya. A field trial was conducted at a paddy field in Kenya Agricultural and Livestock Research Organization-Mwea, Kirinyaga County ($0^{\circ}39^{\prime}S$, $0^{\circ}20^{\prime}E$) from August 2016 to January 2017. Eight lines of NERICA 1 introgressed with Gn1a and/or WFP, and their parents, NERICA 1 and ST12, were grown under 0 (NF) and $75(SF)kg\;N\;ha^{-1}$. At maturity, five hills per plot were harvested to determine the yield and yield components. The number of primary and secondary rachis-branches per panicle was measured on the longest panicle in each hill. Under SF, the introgression of WFP to NERICA 1 increased the number of primary and secondary rachis-branches by 27 and 25%, respectively. On the other hand, Gn1a did not increase the number of primary rachis-branches, whereas the number of secondary rachis-branches was increased by 38% on average. The number of primary and secondary rachis-branches of the lines introgressed with both genes increased by 25 and 56%, respectively. Although grain number per panicle increased 33% by Gn1a, 34% by WFP, and 43% by Gn1a+WFP, the yield increase by Gn1a, WFP, and Gn1a+WFP was only 14, 7, and 14%, respectively. The suppression of the yield increase was mainly attributed to the decline in the filled grain ratio. Under NF, WFP increased the number of primary and secondary rachis-branches by 20 and 19%, respectively. The introgression of both genes increased the former and the later by 19 and 35%, respectively. However, Gn1a did not change them under NF. Thus, even under NF, grain yield increased 11% by WFP and 24% by Gn1a+WFP due to the increased grain number although filled grain ratio declined. Our findings suggest that the introgression of Gn1a and WFP could contribute to the rice productivity improvement in sub-Saharan Africa even under low fertility conditions. Improving filled grain ratio of the lines introgressed with these genes by further breeding and fertilization management will be the focus of subsequent work.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.63 no.3
• /
• pp.205-209
• /
• 2018

'Saemimyeon,' a Tongil-type rice variety (Indica x Japonica), containing high amylose content, is suitable for rice noodle production. Currently, the major parts of the rice processing industry that include products such as rice flour and noodles are expected to partially replace the wheat flour market. The volume of the rice noodle market is growing and can contribute to the rice surplus problems and farmer's income. This study was carried out to promote productivity of 'Saemimyeon' by finding the most suitable transplanting times in Youngnam Province. The transplanting times were May $10^{th}$, May $17^{th}$, May $24^{th}$, May $31^{th}$, June $7^{th}$, and June $14^{th}$ and the planting distance was $30{\times}12cm$. The field experiment was conducted in the Miryang region (southern plain region of Korea) from 2015 to 2017. Our results suggested that the optimum transplanting dates were from May $17^{th}$ to May $31^{th}$, which resulted in an average yield of 750 kg/10 a. The average grain filling rate before May $31^{th}$ was more than 83% and it declined to 75% after June $7^{th}$. The average temperature range from heading to harvesting time was $21{\sim}25^{\circ}C$ and the estimated optimal temperature was $24^{\circ}C$, which is similar to that of May $24^{th}$ by regression equation. It is suggested that low temperature at seed maturation time caused the lower grain filling rate, and therefore 'Saemimyeon' needed to be transplanted before May $31^{th}$ for higher productivity. Estimated optimal transplanting time based on temperature was 1 ~ 2 weeks earlier than the optimum transplanting time for common japonica rice cultivars in Youngnam Province.

• Journal of Animal Science and Technology
• /
• v.45 no.3
• /
• pp.397-408
• /
• 2003

This study was conducted to examine the feeding effects of FFWBG (fermented feedstuff with wet brewer’s grain) and GS(grinding soybean) in Hanwoo steers. For this research, total twenty steers(average body weight : 455.7$\pm$25.9kg) were grouped into control(formula feed), T1(formula feed:FFWBG=60:40), T2(formula feed:GS=80:20), T3(formula feed:FFWBG:GS=50:40:10), and T4(formula feed: FFWBG:GS=40:40:20), each treatment was allocated to four steers. There was a tendency to be increased average daily gain in T1, T2, T3 and T4 compared with the control even though no statistical significance was found. The feed conversion of T1, T2, T3 and T4 were beneficially better than that of control(P<0.05; 8.25, 9.44, 6.69 and 7.71 vs 11.90, respectively). The blood urea nitrogen concentration of T4 was higher than that of control(P<0.05), but the creatinine concentration of T4 was lower than that of control(P<0.05). The glucose concentration of T1, T2, T3 and T4 were higher than that of control(P<0.05; 59.39, 62.44, 62.17 and 54.00 vs 51.00mg/$d\ell$, respectively). The back-fat thickness of T3 was thicker than that of control, T1, T2 and T4. The rib-eye area of T1, T3 and T4 was wider than that of control. Appearances percentage of ‘A’ ranked meat quantity were 66, 33, 75 and 33% in control, T1, T2 and T4, respectively.