• Journal of the Korean Society for Precision Engineering
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• v.15 no.9
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• pp.43-49
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• 1998

The deep hole drilling has an increasing demands because of its wide range applications and its good productivity. The BTA drills are capable of machining for having a large length to diameter ratio in single pass to higher degree of accuracy and surface finish. It's really necessary that the investigation for the deep hole drilling by the BTA drill because its required quality should be satisfied with single pass. This thesis deal with the experimental results obtained during single tube BTA system machining on SM55C steel for different machining conditions. The results of the investigation on the optimum cutting condition selecting and tool life reveals as follows. (1) The optimum cutting condition was cutting speed, V = 42 m/min and feed speed. F = 90 mm/min and the tool life was about 10 meters. (2) Surface roughness was $12\mum$ and the roundness was less using $16mum$single edge BTA drill in testing cutting condition.

• Journal of Forest and Environmental Science
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• v.36 no.4
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• pp.274-280
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• 2020

As the importance of biological resources increases, the conservation technology is becoming important for rarities. This study was conducted to establish an efficient cryopreservation conditions for the Deutzia paniculata, endangered plant species, by using both cryopreservation methods of vitrification and encapsulation. As a result, the sucrose pretreatment seed viability showed up to 30.7% in the treatments. The cryoprotectant treatment improved the viability of the seeds, and was found to be excellent in the vitrification method using PVS3. The vitrification method had over 10% higher germination rate than the seeds preserved by encapsulation. In addition, the germination rate showed a significant difference according to the cryopreservation treatment time, and the germination rate of seeds decreased very much as the long time became longer. Plants germinated from preserved seed in liquid nitrogen showed poor growth compared to untreated, and good growth in PVS3 120 minutes. In addition, the growth of germinated plants by liquid nitrogen treatment time was better in the vitrification method. These results are expected to be useful for long-term preservation of D. paniculata, endangered plants.

• Korean Journal of Metals and Materials
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• v.50 no.10
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• pp.721-728
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• 2012

This paper evaluates the reliability of creep rupture life under service conditions of Alloy 617, which is considered as one of the candidate materials for use in a very high temperature reactor (VHTR) system. A Z-parameter, which represents the deviation of creep rupture data from the master curve, was used for the reliability analysis of the creep rupture data of Alloy 617. A Service-condition Creep Rupture Interference (SCRI) model, which can consider both the scattering of the creep rupture data and the fluctuations of temperature and stress under any service conditions, was also used for evaluating the reliability of creep rupture life. The statistical analysis showed that the scattering of creep rupture data based on Z-parameter was supported by normal distribution. The values of reliability decreased rapidly with increasing amplitudes of temperature and stress fluctuations. The results established that the reliability decreased with an increasing service time.

• Journal of Plant Biotechnology
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• v.48 no.4
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• pp.228-235
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• 2021

The amino acids found in plants play important roles in protein biosynthesis, signaling processes, and stress responses, and as components in other biosynthesis pathways. Amino acid degradation helps maintain plant cells' energy states under certain carbon starvation conditions. Branched-chain amino acid transferases (BCATs) play an essential role in the metabolism of branched-chain amino acids (BCAAs) such as isoleucine, leucine and valine. In this paper, we performed genome-wide RNA-seq analysis using CsBCAT7-overexpressing Arabidopsis plants. We observed significant changes in genes related to flowering time and genes that are germination-responsive in transgenic plants. RNA-seq and RT-qPCR analyses revealed that the expression levels of some BCAA catabolic genes were upregulated in these same transgenic plants, and that this correlated with a delay in their senescence phenotype when the plants were placed in extended darkness conditions. These results suggest a connection between BCAT and the genes implicated in BCAA catabolism.

• Design & Manufacturing
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• v.17 no.1
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• pp.7-12
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• 2023

Recently, with the emergence of the 4th industrial revolution, the demand for smart factories and factory automation is increasing. In this study, a tool life prediction program was developed to select optimal machining conditions using CNC milling equipment, which is widely used in flexible production and automation. The equipment used in the experiment was Hwacheon Machine Tool's 5-axis machining equipment, and the tool used was a 17F2R tool. For the machining path, the down-milling cutting method was selected and long-term machining was performed. The analysis standard for side wear on the tool was set at 0.1 to 0.2 mm, and tool life data and wear data were obtained in the cutting experiment. The program was created through the data obtained from the experiment, and a prediction rate of over 90% was secured when comparing the experimental data and the predicted data.

• Journal of Drive and Control
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• v.20 no.3
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• pp.42-49
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• 2023

In this study, the safety of fastening device for the agricultural by-product collector was evaluated according to the driving ground conditions by deriving the stress, static safety factor, and fatigue life using dynamic simulation. A 3D modeling of agricultural by-product collector was carried out, and simulation model was developed by applying the material properties. As a result of dynamic simulation, the magnitude of the maximum stress generated in the fastening device was the highest when driving on the flat off-road, followed by sloped pave-road and flat pave-road. Static safety factor and fatigue life were the highest when driving on the flat pave-road, followed by sloped pave-road and flat off-road. The safety of fastening device was confirmed that static safety factor was more than 1.0 and service life exceeded 9 years in all driving ground conditions.

• Journal of Mushroom
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• v.22 no.3
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• pp.81-86
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• 2024

Cordyceps militaris is widely used in China, Korea, and other Asian countries as both a traditional medicinal ingredient and an edible fungus. This study aimed to optimize the growth conditions and fruiting body production of C. militaris by investigating various culture media and physical parameters such as pH, aeration, illumination, temperature, spawn materials, and oat-sawdust-based substrate formulations. After a 7-day incubation period, oats with a pH of 6.0, under sealed and illuminated conditions at 32℃, demonstrated the most effective mycelial growth. Substrates consisting of 70% oat and 30% sawdust had the shortest incubation time of 30.5 days for fruiting body formation. The basidiospores showed a typical germination pattern where the sporidium produced a single germ tube that elongated, and branched to form monokaryotic primary mycelia. In conclusion, using oats as a substrate in the cultivation of C. militaris could reduce production costs and help protect the environment.

• Journal of Mushroom
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• v.22 no.3
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• pp.73-80
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• 2024

We studied the effects of initial pH, different nitrogen sources, and cultivation methods (shake flask and static culture) on biomass production, exopolysaccharides (EPS), and adenosine by Paecilomyces tenuipes. Relatively low pH levels were optimal for mycelial growth and EPS production. Yeast extract was the most effective organic nitrogen source for EPS production, whereas soybean extract was the best for adenosine production. A high C/N ratio was beneficial for adenosine production; however, excessively high C/N ratios reduced adenosine production. Static fermentation significantly increased adenosine production. A Box-Behnken design was used to optimize adenosine production; the optimal conditions for adenosine production by P. tenuipes were pH 7.0, soybean concentration of 3%, and a static culture period of 20 days, with the maximum adenosine production of 141.10 mg/L (predicted value: 128.05 mg/L).

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.6 no.1
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• pp.50-56
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• 2010

Fatigue has been known as a major degradation mechanism of ASME class 1 components in nuclear power plants. Fatigue damage could be accelerated by combined interaction of several loads and environmental factors. However, the environmental effect is not explicitly addressed in the ASME S-N curve which is based on air at room temperature. Therefore many studies have been performed to understand the environmental effects on fatigue behavior of materials used in nuclear power plants. As a part of efforts, we performed low cycle fatigue tests under various environmental conditions and analyzed the environmental effects on the fatigue life of SA508 Gr. 1a low alloy steel by comparing with higuchi's model. Test results show that the fatigue life depends on water temperature, dissolved oxygen and strain rate. But strain rate over 0.4%/s has little effect on the fatigue life. To find the cause of different fatigue life with ANL's and higuchi's model, another test performed with different heat numbered and heat treated materials of SA508 Gr. 1a. On a metallurgical point of view, the material with bainite microstructure shows much longer fatigue life than that with ferrite/pearlite microstructure. And the characteristics of crack propagation as different microstructure seem to be the main cause of different fatigue life.

• Korean Journal of Food Science and Technology
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• v.19 no.6
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• pp.463-470
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• 1987

In order to develop a rapid predicting method of the shelf-life of moisture sensitive foods and establish their proper packaging methods, the qualify changes and shelf-life of dired laver as a model food were studied by the computer simulation. A mathematical model of the relationship between the rate constants of chlorophyll a and water activity was established at $10^{\circ}C,\;25^{\circ}C$ and $40^{\circ}C$. Computer simulation to predict water activity and chlorophyll a was developed by considering the simultaneous influence of storage conditions such as water content of products, storage temperature and relative humidity, packaging materials. Simulated quality changes of dried laver was in good agreement with the experiment data. Chlorophyll a and sensory score decreased as the water activity increased. And correlation coefficient between the sensory scores and the contents of chlorophyll a was very high as 0.991. The critical water activity by sensory evaluation was around 0.55. The shelf-life of dried laver packaged with plastic films could be predicted from the above results in various storage conditions.