• Journal of the Korean Society for Heat Treatment
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• v.4 no.1
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• pp.1-12
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• 1991

This study has been performed to find out the effect of austenitizing temperature, austempering temperature and its holding time, and tempering cycle on the mechanical properties such as impact resistance, hardness etc. of AISI $M_2$ Mo series high speed tool steel austempered or tempered after austempering treatment. The results obtained from the experiment are as follows ; (1) Optical micrograph has revealed that the transformation rate of bainite is delayed as the austenitizing temperature increases and that bainite is most apparently transformed at an austempering temperature of $290^{\circ}C$. (2) The amount of retained austenite during austempering has been analysed to be increased by the X-ray diffraction technique as the transformation product of bainite is increased. It has also been shown that the longer the holding time of austempering, the more the transformation quantity of bainite is formed, exhibiting, however, that the rate of bainitic transformation is considerably retarded after a certain period of holding time elapses. (3) Hardness measurement has shown that hardness values obtained after austempering increase with decreasing the amount of retained austenite. (4) The austempering and then tempering cycle has been formed to give hardness values which are more greatly improved as austenitizing temperature is increased. (5) The mechanical property of the specimen primary-tempered for 1 hour at $550^{\circ}C$ after austempering for 2 hours at $290^{\circ}C$ from the austenitizing temperature range of $1180^{\circ}C$ to $1210^{\circ}C$ have been estimated to be good values.

• Corrosion Science and Technology
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• v.16 no.4
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• pp.175-182
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• 2017

Galvanic current measurement, polarization curves, electrochemical impedance spectroscopy and weight loss test were used to study the corrosion behavior of carbon steel before and after carbon fibers coupling to the carbon steel in simulated concrete pore solutions, and the film composition on the steel surface was analyzed using XPS method. The results indicate that passive film on steel surface had excellent protective property in pore solutions with different pH values (13.3, 12.5 and 11.6). After coupling with carbon fibers (the area ratio of carbon steel to carbon fiber was 12.31), charge transfer resistance $R_{ct}$ of the steel surface decreased and the $Fe^{3+}/Fe^{2+}$ value in passive film decreased. As a result, stability of the film decreased and the corrosion rate of steel increased. Decreasing of the area ratio of steel to carbon fiber from 12.3 to 6.15 resulted in the decrease in $R_{ct}$ and the increase in corrosion rate. Especially in the pore solution with pH 11.6, the coupling leads the carbon steel to corrode easily.

• Plant Resources
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• v.8 no.3
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• pp.202-208
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• 2005

Osmotic stress is one of major limiting factors in crop production. In particular, seasonal drought often causes the secondary disease in the field, resulting in severe reduction in both quality and productivity. Recent efforts have revealed that many genes encoding protein kinases play important roles in osmotic stress signal transduction pathways. Previously, the AtSIK (Arabidopsis thaliana Stress Inducible Kinase) mutants have shown to enhance tolerance to abiotic stresses, accompanying with higher expression of abiotic stress-related genes than did the wild-type plants. In this study, we have transformed potato (cv. Taedong Valley) with the AtSIK expression cassette. Both PCR and RT-PCR using AtSIK-specific primers showed stable integration and expression of the AtSIK gene in individual transgenic lines, respectively. Foliar application of herbicide ($Basta^{(R)}$) at commercial application rate (0.3% (v/v)) revealed another evidence of stable gene introduction of T-DNA which includes the bar gene for herbicide resistance. Overexpression of the AtSIK gene under dual CaMV35S promoter increased sensitivity to salt stress (300 mM NaCl), which was demonstrated by the reduction rate of chlorophyll contents in leaves of transgenic potato lines. These results suggest that possible increase of osmotic tolerance in potato plants may be achieved by antisense expression of AtSIK gene.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.6
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• pp.402-411
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• 2023

In order to examine the effect of cementite precipitated on the steel surface on the carburizing rate, the carburizing process was carried out at various boost times to measure the mass gain and carbon flux, phase analysis and carbon concentration analysis were performed on the surface of the carburized specimen. In the case of the only boost type, the longer the boost time, the more the mass gain by the diffused carbon follows the parabolic law and tends to increase. In particular, as the boost time increased, the depth of cementite precipitation and the average size of cementite on the steel surface increased. At a boost time of 7 min, the fraction of cementite precipitated on the surface is 7.32 vol.%, and the carburizing rate of carbon into the surface (surface-carbon flux) is about 17.4% compared to the calculated value because the area of the chemical (catalyst) where the carburization reaction takes place is reduced. The measured carbon concentration profile of the carburized specimen tended to be generally lower than the carbon concentration calculated by the model without considering precipitated cementite. On the other hand, in the pulse type, the mass gain by the diffused carbon increased according to the boost time following a linear law. At a boost time of 7 min, the fraction of cementite precipitated on the surface was 3.62 vol.%, and the surface-carbon flux decreased by about 4.1% compared to the calculated value. As a result, a model for predicting the actual carbon flux was presented by applying the carburization resistace coefficient derived from the surface cementite fraction as a variable.

• Journal of Biosystems Engineering
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• v.24 no.4
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• pp.309-316
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• 1999

This study was conducted to develop a large-scale rice polisher with double polishing stages for producing clean rice with high quality in rice processing complexs. The performance of the developed rice polisher was evaluated and improved. The results obtained from this study were as followings : 1. A large-scale rice polisher with double polishing stages was developed, which consisted of two polishing chambers(polishing part I and II), two spraying parts, a feeding part, power of 37kW, control panel, etc. Especially, the purpose of polishing part Iwere to uniformly mix white rice sprayed with water and to remove bran particles from the rice. the roller surface of the polishing part I was coated with chromium. 2. The capacity of the developed rice polisher was 4t/h. The broken rice rate of the polisher was less than 0.2%, compared with about 1% of others. 3. The whiteness increment of the developed polisher was 2.6~3.0% compared with about 2.3~2.5% of others. 4. The energy consumption of the developed polisher was 0.5kWh/100kg. 5. The developed polisher was improved with the angle change of screen slot of the polishing chamber I. The broken rice rate was reduced from about 0.5% to about 0.2% as the max. internal pressure of the polishing chamber II decreased by 0.4kg/$\textrm{cm}^2$ due to the increase of resistance in the polishing chamber I. The whiteness of the polisher showed more than 38~39. 6. The developed rice polisher showed high performance, compared with other domestic and foreign polishers.

• Tribology and Lubricants
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• v.31 no.6
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• pp.258-263
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• 2015

Biodiesel is an environmentally-friendly fuel with low smoke emission because it contains about 10% oxygen. Biodiesel fuel prepared by transesterification of vegetable oil or animal fats is susceptible to auto-oxidation. The rate of auto-oxidation depends on the number of methylene double bonds contained within the fatty acid methyl or ethyl ester groups. Biodiesel may be easily oxidized under several conditions, i.e., upon exposure to sunlight, temperature, oxygen environment. Maintenance of the fuel quality of biodiesel requires the development of technologies to increase the resistance of biodiesel to oxidation. Treatment with antioxidants is a promising approach for extending the shelf-life or storage time of biodiesel. The chemical properties of various amine-based antioxidants were evaluated after synthesis of the antioxidants by condensation of phenylenediamine with alkylamines at room temperature. In general, the oxidative stability can be assessed based on various experimental parameters. Such parameters may include temperature, pressure, and the flow rate of air through the samples. The Rancimat method (EN14112) was selected because it is a rapid technique that requires very little sample and provides good precision for oxidative degradation analysis. Specifically, the EN 14112 technique provides enhanced efficiency for oxidative stability evaluation when a larger ester head group is utilized. Therefore, this technique was employed for evaluation of the oxidation stability of biodiesel by the Rancimat method (EN14112).

• Current Research on Agriculture and Life Sciences
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• v.2
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• pp.42-55
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• 1984

The direction of scientific researches on tree improvement and forest management in several universities and research institutes in Japan can be summarized as follows: They put a great emphasis on sugi, Cryptomeria japonica and cypress, Chamaecyparus oblusa which are two major conifer species largerly planted in the Japanese forestry. In the research of sugi, a great concern has been made in evaluating inheritance of forest tree, quantitative characters and genetic parameter of growth, and in breeding for resistance to diseases and insects and to all the natural calamities. Interaction between environmental conditions and genetic nature of tree can be concerned factors in relation with forest damage, together with silvicultural conditions and pest infestation. Selfing hybrids of $F_1$ made from crossing twisted-leaf sugi, defomity leaf type and midori sugi, normal leaf type segregated the normal needle, twisted needle, green leaf and albino leaf type. It seemed that separation of many defomity individuals can be governed by two dominant complementary genes and from the near loci of which it was detected lethal genes. 52% of Japanese forestry is occupied by the small forest landowners like Korean forestry. This made difficulty for forest improvement such as progressive afforestation and for capital accumulation form forestry. The Forest Corporation was established at first in 1959 to aming at productive forestry structure and forest management, and afforestation. For these purpose, 35 Forest Corporations are at moment operating throughout Japan. However, investment in forestry business becomes less attractive since the wage in forest production duction increased in higher trend. than timber price. Therefore, an artifical afforestation becomes yearly decreased. At present. the self-sufficient rate of timber production in Japan is about 35%, and so a great effort is being made to increase self-sufficient rate of timber production.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.8
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• pp.693-701
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• 2016

In this study, notch defects are evaluated using fracture mechanics. To understand the effects of notch defects, FE analysis is conducted to predict the limit load and J-integral for middle-cracked and single-edge cracked plates with various sizes of notch under tension and bending. As the radius of the notch increases, the energy release rate also increases, although the limit load remains constant. The values of fracture toughness($J_{IC}$) of SM490A are determined for various notch radii through FE simulation instead of conducting an experiment. As the radius of the notch increases, the energy release rate also increases, together with a more significant increase in fracture toughness. To conclude, as the notch radius increases, the resistance to crack propagation also increases.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.12-12
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• 2017

Genetic improvement in potato can be carried out through several approaches, as sexual crosses, somatic hybridization, mutation and genetic engineering. Although the approach is different, but the goal is the same, to get a superior cultivar. Mutation and genetic engineering are very interesting methods for genetic improvement of potato plants. Mutation by gamma-ray irradiation have been performed to get some new potato cultivars which are more resistant to disease and have higher productivity. We have carried out a mutation of some potato cultivars and obtained some excellent clones to be potentially released as new superior cultivars. By the mutation method, we have released one potato cultivar for the French fries industry, and we registered one cultivar of potato for chips, and two cultivar for vegetable potatoes. Actually we are doing multi-location trial for three clones to be released as new cultivars. Through genetic engineering, several genes have been introduced into the potato plant, and we obtained several clones of transgenic potato plants. Transgenic potato plants containing FBPase gene encoding for fructose bisphosphatase, have a higher rate of photosynthesis and higher tuber productivity than non-transgenic plants. This result suggests that FBPase plays an important role in increasing the rate of photosynthesis and potato tuber productivity. Some transgenic potatoes containing the Hd3a gene are currently being evaluated for their productivity. Over expression of the Hd3a gene is expected to increase tuber productivity and induce flowering in potatoes. Transgenic potato plants containing MmPMA gene encoding for plasma membrane ATPse are more tolerant to low pH than non-transgenic plants, indicating that plasma membrane ATPase plays an important role in the potato plant tolerance to low pH stress. Transgenic potato plants containing c-lysozyme genes, are highly tolerant of bacterial wilt diseases caused by Ralstonia solanacearum and bacterial soft rot disease caused by Pectobacterium carotovorum. Expression of c-lyzozyme gene plays an important role in increasing the resistance of potato plants to bacterial diseases.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.6
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• pp.405-411
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• 2013

A sediment transport calculation considering cohesive force is proposed to deal with the transport phenomena of cohesive sediment. In the proposed calculation, each sand particle is assumed to be surrounded by a thin layer of mud. The critical Shields parameter and bed-load sediment transport rate are modified to include the cohesive force acting on the sand particle. The proposed calculation is incorporated into a two-way coupled fluid-structure-sediment interaction model, and applied to wave-induced topographic change of artificial shallows. Numerical results show that an increase in the content ratio of the mud, cohesive resistance force per unit surface area and water content cause increases in the critical Shields parameter and decreases in the bed-load sediment transport rate, reducing the topographic change of the shallow without changing its trend. This suggests that mixing mud in the pores of the sand particles can reduce the topographic change of shallows.