Cracks are an inevitable problem during the use of materials, and flexible sensors with self-healing capability are of great importance for applications in wearable devices and skin-like electronic devices. This paper prepared self-healing flexible strain sensors by compounding self-healing polyurethane with carbon nanotubes. First, by changing the ratio of disulfide bonds, a good balance between mechanical properties and self-healing efficiency was achieved in the prepared self-healing polyurethane. The most balanced sample reached 12.28 MPa in tensile strength, after 24 h of self-repair at 30 °C, the tensile strength was 7.75 MPa, and the self-repair efficiency was 63.11%; after 24 h of self-repair at 80 °C, the tensile strength was 11.64 MPa, and the self-repair efficiency reached 94.79%. Then the sensors prepared by compounding with carbon nanotubes showed a good electrochemical response, and both slow and fast repeated bending of the finger wearing the sensors yielded significantly different electrical signal changes, and the sensors were cut off and still had the same function after self-repair at 30 °C, demonstrating their excellent potential for applications in soft robots, wearable devices, etc.

Carbon nanotubes (CNTs) were added into the self-healing polyurethane materials as conductive filler, the mass fraction of carbon nanotubes was adjusted, and 1% polyaniline was doped. The conductive self-healing polyurethane composites with different carbon nanotubes content (PU)-1/3/5/8/10 were prepared, and analyzed and tested. The result shows that the permeability threshold value of the composite material is 8wt%, and the comprehensive performance of the composite material PU-8 is the best; the resistance of PU-8 is 1278Ω, PU-8P has a resistance of 1400Ω; using an infrared camera, it can be seen that the material can reach 143.3 °C under the DC current of 0.1A, reaching the temperature condition when the material is repaired; the swelling test shows that the PU-8P equilibrium swelling rate is 177%, the gel content is 52.67%, and there is no dissolution in dimethyl sulfoxide. Solvent stability is better than PU-8;DSC test shows that the glass transition temperature of the soft segment of PU-8P is 43 °C, and the glass transition temperature of the hard segment is − 55 °C, which is not much different from that of PU-8; TG test shows that the epitaxial starting temperature of PU-8P is 365 °C; the observation photo is magnified by a stereo microscope at ten times and the PU-8P sample is cut of in the middle at room temperature, applying a constant voltage of 30 V, the cracks disappeared. The material cracks realized self-healing with electricity, and the repair efficiency reached 20.5%.

Isotropic pitch-based carbon fiber was successfully prepared from tetrahydrofuran-soluble fraction of coal tar pitch cocarbonization with petrolatum by air-blowing. The effects of reaction temperature and time, amount of petrolatum added on the composition and spinning properties of resultant pitches were investigated. It indicated that petrolatum could effectively improve the softening point, aromaticity, hydrogen content and molecular weight of the resultant pitches by promoting cross-linking and dehydrogenation polymerization reactions at low air-blowing temperature. Moreover, more aliphatic and naphthenic structures had been introduced into resultant pitches as addition of petrolatum and also inhibited the generation of quinoline-insoluble particles. The obtained green fibers were facile to be stabilized and carbonized and the resultant carbon fibers showed fully isotropic and finer, uniform diameter with smooth surface and higher tensile strength of up to 0.92 GPa. It provided a facile chemical modification method for isotropic pitch-based carbon fiber production.

Hay-making is one of the most common way for forage preservation in livestock industry. The quality and production of hay could be affected by various factors. This experiment was conducted to investigate the effect of tedding time and frequency on drying rate and feed value of forage rye (Secale cereale L.) hay. Rye was harvested on heading stage using mower conditioner. Hay was tedded at each set hour(09:00, 13:00 and 17:00) and sampled at each set hour to determine dry matter (DM) content. After two months’ preservation, CP (crude protein), ADF (acid detergent fiber), NDF (neutral detergent fiber), IVDMD (in vitro dry matter digestibility), TDN (total digestible nutrient), RFV (relative feed value), DM loss, visual scores and total fungi count were determined for estimation of hay quality. Tedding was necessary for both speeding up drying rate and improving forage quality. Tedding at 17:00 showed lower NDF content (p<0.05), and also higher RFV value was found compared with tedding at 9:00 and 13:00 (p<0.05). On the other hand, it was observed that more DM losses would be found when tedding later (p<0.05). Tedding in 1~3 times per day were lower in ADF and NDF content (p<0.05), increased CP, TDN and RFV (p<0.05), got less DM loss (p<0.05), and contained less fungi during conservation compared with no tedding (p<0.05). On the other hand, tedding too frequent caused more DM loss (p<0.05). In conclusion, for shorter drying process and higher quality of forage rye hay, tedding at 13:00∼17:00 for 1∼2 times per day was recommended in this study.

This experiment was carried out to determine the effect of organic fertilizer and seed mixture on productivity, botanical composition and forage quality in middle areas(Geumsan, 250m sea level) pasture. Total six experimental pastures (orchardgrass, timothy and tall fescue based seed mixture and with or without organic fertilizer) were established in autumn, 2014 and evaluated productivity and agronomic characteristics from 2015 to 2016. Plant heigh was higher in orchardgrass based mixture and orchardgrass and tall fescue based mixture were higher in 2nd harvest. There was not found the significant difference among treatment(P<0.05) in dry matter (DM) content. Botanical composition in 1st harvest was higher weed portion in orchardgrass based mixture and legumes was disappeared at 3rd harvest in all treatments. Fresh and dry matter yield was higher in 2nd year than 1st year. In 1st year, orchardgrass based mixture with organic fertilizer plot was the highest(P<0.05) DM yield, but tall fescue based mixture with organic fertilizer was the highest in 2nd year. Content of crude protein (CP) was the highest in tall fescue based mixture and Timothy based mixture showed low in ADF (acid detergent fiber) and NDF (neutral detergent fiber) content. But the content if in virto dry matter digestibility was higher than others. In 2nd year, the nutritive value of 2nd and 4th harvested grasses were higher and average RFV (relative feed value) value was the highest at 4th harvest. According to this result, orchardgrass and tall fescue based mixture would be recommendable for farm who considering productivity and timothy based mixture would be recommendable for considering forage quality in middle areas of Korea.

Hay-making is one of the most common forage preservation practices in livestock operations. The objective of hay-making is to minimize nutrient loss by shortening field drying time. Measuring the impacts of cutting height of forage crop is necessary to optimize hay production balancing yield and quality, in order to obtain substantial biomass increase through harvest of regrowth. This experiment was conducted to investigate the impact of cutting height of rye (Secale cereale L.) on drying rate and hay quality. Heading stage rye was harvested at 8cm or 15cm stubble heights. Hay was daily tedded at 09:00 and sampled at 09:00, 13:00 and 17:00 to determine moisture content (MC). After two month of preservation, CP (crude protein), ADF (acid detergent fiber), NDF (neutral detergent fiber), IVDMD (in vitro dry matter disappearance), TDN (total digestible nutrient), RFV (relative feed value), DM (dry matter) loss, visual scores and total fungi count were determined for estimation of hay quality. Cutting height at 15cm could enhance the drying rate and CP content (p<0.05), but also increases DM loss (p<0.05) compared to cutting at 8cm. Cutting heights did not affect ADF, NDF, IVDMD, TDN and RFV value (p>0.05). Visual scores of rye hays cutting at 8cm and 15cm, ranged from 83 to 85. Cutting at 8cm tended to maintain higher core bale temperature and fungal count than cutting at 15cm during preservation, but there was no significant difference.

This experiment was conducted to comparison study on the productivity for certified varieties of import adaptability of silage corn in Pyeongchang area. Total eight varieties (Gangpyeongok, 31N27, 32P75, 32W86, P3156, P3394, DK 689 및 DK 729) were evaluated. The experimental design was 8 treatment of randomized block with three replications. Corn varieties were cultivated in experimental field of Pyeongchang campus, SNU from 1 May to 2 September, 2015 and plot size was 15㎡. Plant height of 32W86 and ear height of Gwanpyeongok was the highest (p<0.05). Tasseling and silking date was 27 July-3 August and silking occurred after 1-3 day of tasseling. Average day to silking was 92 days and that of 31N27 variety was short (p<0.05). The varieties of DeKalbo Company (DK 689 and DK 729) required more times to silking. Average GDD (growth degree day) of eight varieties was 1,023℃ and P3352 was the lowest GDD. In the trials of resistance evaluation, P3394 was strong in disease, P3156 was the highest in insect. All varieties did not show the lodging and variety of DK 729 showed the highest stay green score (p<0.05). Average dry matter content was 30.77%, it showed higher trend in DM. 32W86 was the highest DM content among the varieties, but there was no significant difference among varieties (p>0.05). The weight per ear was the highest in 32W86 and the lowest in Gwanpyeongok. The ration of ear to whole plant was higher in 32W86 and P3394, but it was not found the significant difference (p>0.05). Average yield of fresh and DM was 59,017 and 13,476 kg/ha, respectively. DK 689 showed higher DM and TDN yield than others, but there was not significant difference (p>0.05). According to results, the difference of productivity was not found among certified variety of import adaptability of silage corn. The varieties Gwanpyeongok, 32W86 and 32P75 would be recommendable in Pyeongchang area for stable cultivation.

This study amied to determine the effect of species and seed mixture on productivity, botanical composition and forage quality in middle mountainous region (Geosan) pasture. Total seven experimental pastures (T1 : Orchardgrass, T2 : Timothy, T3 : Tall fescue, T4 : Perennial ryegrass, T5 : Kentucky bluegrass, T6 : Timothy + Orchardgrass + Tall fescue + Alfalfa, T7 : Timothy + Orchardgrass + Kentucky bluegrass + White clover) were established in autumn, 2014 and evaluated for productivity and agronomic characteristics for 2015. Plant heigh was high in Orchardgrass and Perennial ryegrass pasture. Dry matter (DM) content was high in Kentucky bluegrass. Botanical composition in 1st harvest was high in shrub, but the grass composition was high in 2nd and 3rd harvest. Fresh and DM yield were higher in Orchardgrass and Perennial ryegrass (p<0.05); whreras, Kentucky bluegrass was the lowest. In seed mixture pasture, yields of T6 plot (Tall fescue) were higher than those of T7 (Kentucky bluegrass). Average CP (crude protein) content of 2nd and 3rd cutting time was 16.91 and 14.79%, respectively and Kentucky blue grass was the highest in 3rd cutting time by 17.57%. IVDMD (in vitro dry matter digestibility) showed low in 1st cutting and Kentucky bluegrass was the lowest in every cutting time. TDN (total digestible nutrient) content was the highest in 3rd cutting and the lowest in 1st cutting. These results indicated that Orchardgrass, Perennial ryegrass and T6 are recommendable for productivity and Timothy, Perennial ryegrass and T7 are recommendable for forage quality.

In this paper, fly ash was investigated as a basic Si-Al ingredient of geopolymer. Based on compressive and flexural strength, the replacement percentage of fly ash and 3 types of curing regimes were studied to obtain the optimum synthesis condition. The results showed that geopolymer containing 30% fly ash that was prepared at 80˚C for 8 hours, exhibited high mechanical strength. The compressive and flexural strength of the fly ash based geopolymer were 32.2 and 7.15MPa, respectively. In order to investigate the durability behavior of fly ash based geopolymer concrete, CI permeability, freeze-thaw tests were also carried out. The measured results indicated that fly ash based gopolymer concrete had 2.63 times lower coefficient of chloride-ion diffusion and could withdraw 2.2 times more freeze-thaw cycles as compared to Portland concrete with the same compressive strength.

Soybean has been cultivated in China for 5,000 years. The soybean cyst neamtode (SCN), Heterodra glycines, was recongnized in Northeastern China in 1899. Currently, it is known to occur in 12 provinces. The biology of SCN was investigated in several provinces. Six races of SCN were identified (race 1, 2, 3, 4, 5 and 7). About f10,000 soybean germplasm lines were evaluated for their resistance to race 1, 3, 4 and 5 of SCN. At least two black-seeded cultivars are resistant to all four races. Several tolerant soybean cultivars with yellow seed coat were released and are in production. Additional resistant cultivars are being developed. Nematicides were not applied in production Potential biocontrol agents and related aspects are being investigated.

Although the overall structure of the chloroplast genome is generally conserved, a number of sequence variations have been identified, which are valuable for plant population and evolutionary studies. Here, we constructed a chloroplast variation map of 30 landrace rice strains of Korean origin, using the Oryza rufipogon chloroplast genome (Genbank: NC_017835) as a reference. Differential distribution of single nucleotide polymorphisms (SNPs) and indels across the rice chloroplast genome is suggestive of a region-specific variation. Population structure clustering revealed the existence of two clear subgroups (indica and japonica) and an admixture group (aus). Phylogenetic analysis of the 30 landrace rice strains and six rice chloroplast references suggested and supported independent evolution of O. sativa indica and japonica. Interestingly, two “aus” type accessions, which were thought to be indica type, shared a closer relationship with the japonica type. One hypothesis is that “Korean aus” was intentionally introduced and may have obtained japonica chloroplasts during cultivation. We also calculated the nucleotide diversity of 30 accessions and compared to six rice chloroplast references, which shown a higher diversity in the indica and aus groups than in the japonica group in lower level substitution diversity.