• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.488-491
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• 2005

Abrasive Jet Micromachining (AJM) is a process that uses high pressure air with micron-sized particles to erode a substrate. It has been considered as the most economic and appropriate technique to pattern glass surfaces for the flat panel applications. To accelerate the industrialization of AJM, it is necessary to understand the erosion mechanisms thoroughly. Thus, this paper introduces a new method to model the erosion mechanism in AJM. The model is developed by using the concept of the accumulation of the microdeformation caused by each particle. And this paper proposes the model added the effects of second impact. The developed model is used to simulate the erosion profile, and is compared with the model considered only first impact. It can be concluded that the proposed model predicts the erosion profile more accurately.

• Korean Journal of Medicinal Crop Science
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• v.26 no.5
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• pp.391-400
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• 2018

Background: Atractylodes radix is a well-known medicinal crop having many physiological effects. This study was conducted to select useful Atractylodes japonica ${\times}$ Atractylodes macrocephala (AJM) cultivars by comparing anti-oxidative and anti-inflammatory efficacies. Methods and Results: Seven extracts from AJM cultivars were used to treat lipopolysacchride (LPS)-treated BV2 cells, and the effects on cell viability and inhibition on reactive oxygen species (ROS) and nitric oxide (NO) production were analyzed. In vitro scavenging activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and peroxynitrite ($NOO^-$) radicals were also investigated. Contents of total phenol, atractylenolide I, and atractylenolide III in the AJM extracts were measured using high performance liquid chromatography (HPLC) or spectrophotometry. The experiments show that none of the seven extracts was cytotoxic above 89.2% at $20-250{\mu}g/m{\ell}$. Extracts of Gowon, Dawon, Sangchul, and Huchul inhibited ROS generation in a dose-dependent manner, and Sangchul extract showed the highest inhibition on ROS production. All the AJM extracts showed effective inhibitory activity after on NO release in the LPS-treated BV2 cells, and Sangchul extract showed the highest activity. Sangchul extract had the most potent scavenging activities for $NOO^-$ and had some DPPH radical scavenging effect. Sangchul extract also had the highest content at total phenol and atractylenolide I content. Atractylenolide III was not detected in the AJM extracts. Conclusions: The results suggested that Sangchul was the most useful anti-oxidative and anti-inflammatory resource among the AJM cultivars.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.162-162
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• 2017

Atractylodes japonica and Atractylodes macrocephala belongs to Atractylodes genus and theirs roots are used as 'Baek-chul'(White atractylodes rhizome) in Korea Pharmacopoeia. 'Baek-chul' widely used in traditional herbal remedies in Asia. Concurrently, the 'Baek-chul' demand enormously increased in the market due to the growing interest in favoring health benefits but it is depend on import from China. Thus we conducted breeding research to solve the problems associated with domestically cultivated 'Baek-chul' such as low productivity and low disease tolence. We crossed A. japonica (female parent) and A. macrocephala (male parent) in the greenhouse in September 2000. the next season 119 crossed line seeds were collected and germinated in the green house. Among them we selected the good lines in the same season. then conducted replicated yield trials (RYT) in 2014 to local adaptability test (LAT) in 2015-2016. The results showed that the 'AJM16' line has beneficial charactersitcs like, increased plant height, large rhizome diameter, narrow leaf width compared with a 'Sang-chul' (check cultivar) and varied flower color from A. japonica (female parent). The line 'AJM16' was also exhibited decreased anthracnose symptoms(Colletotrichum gloeosporides Penz.). Simultaneously the root yield of AJM16 was 2,409 kg per are, which was increased 130% higher yield compared to 'Sang-chul' (check cultivar) at three various regions from 2015 to 2016. Therefore, we named AJM16 as new cultivar 'Man-chul'. According the results, we have developed a new Atractylodes spp. hybrid cultivar 'Macn-chul' with high yielding and disease tolerance by National Institute of Horticulture and Herbal Science, RDA, in 2016.

• Journal of Welding and Joining
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• v.6 no.3
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• pp.37-42
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• 1988

The Hole Drilling Method(HDM) is widely used to measure residual stresses in the welded structures. The purpose of this study is to evaluate the accuracy fo measuring residual stresses when drilling the hole by Air-abrasive Jet machine(AJM). Simulated residual stresses wre introduced by applying known stresses to steel bars. These known streses were then compared with measured stresses relaxed from hole drilling. the obtained results are summarized as follows; 1) It was possible to obtain well defined holes with the nozzle designed for this study. 2) If the hole shape is not cylindrical, critical may occur. 3) In the uniaxial strain field, the measurement error of the maximum principal stress was within .+-.10 percent. The orientation angle of the maximum principal stress was within 8.deg. from the given directioin. 4) meausrements were made varying hole depths. Little or no change of stresses occurs since holse were drilled more than the depth of the 0.6 times diameter. 5) The air-abrasive jet machining for drilling holse does not cause appreciable apparent stresses which si critical to measure residual stresses.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.535-536
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.503-504
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.663-664
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• 2007

• Korean Journal of Medicinal Crop Science
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• v.14 no.2
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• pp.107-112
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• 2006

Two Atractylodes species, A. japonica Koidz. ex Kitam. (AJ) and A. macrocephala Koidz (AM) were used in this study. AJ population had higher amounts of Sesquiterpenoids and stronger tolerance to root rot but less vigor of root growth than AM population. Two populations (AJ and AM) were crossed to make interspecific hybrid population. A total of 98 lines propagated clonally were selected from a cross of AJ and AM, and evaluated for contents of sesquiterpenoids, atractylon (ATLN) and atractylenolide III (AT3) using high performance liquid chromatography (HPLC), and growth characters such as plant height, stem number and root weight. HPLC profiles of the hybrids were compared with those of parent plants, and it demonstrated the production of introgression hybrid by crossing between AJ and AM. Of 98 clonal lines,10 lines were selected by 10% level based on the growth vigor and tolerance to root rot, and AJM2102-51 line showed the heaviest root weight (117.1 g/plant) among them. A total of 98 hybrid lines contained on average $0.16\;{\pm}\;0.10\;mg/g$ of $AT3,\;2.00\;{\pm}\;1.37\;mg/g$ of ATLN, and $2.16\;{\pm}\;1.40\;mg/g$ of total sesquiterpenoids, showing high coefficients of variation (above 65%). Ten lines having high contents of sesquiterpenoids were selected, and AJM2101-15 had the highest amount (9.83 mg/g) of ATLN, and showed 40.8 g/plant of root weight similar to mean value (39.9 g/plant) of hybrid lines. The result showed that the introgression of both characters of vigorous growth from AM and high sesquiterpenoids content from AJ could be possible to make new hybrid lines by crossing between AJ and AM.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.379-382
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• 2004

Abrasive jet machining (AJM) has a large number of parameters such as powder flow rate, air pressure, diameter of abrasive, stand off distance, material hardness and fracture toughness, etc. It is not easy matter to control those parameter. To achieve high accurate machining, in this study, Taguchi method was used to select process parameters. The objective of the optimization was to get higher material removal rate (MRR). From the experiments and analysis, some process parameters were found to make efficient machining.

• Journal of Welding and Joining
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• v.8 no.4
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• pp.76-82
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• 1990

Lots of research works have been done to improve the accuracy of the hole drilling method to measure residual stress by many investigators. In this study, first, size effect of specimen was analyzed based on the solution of hole in a strip under tension. If the ratio of hole diameter tothe strip width is less than 0.2, the stress distribution around hold may be given from the solution of hole in an infinite plate. Second, the residual stress above $0.6{\sigma}_y$(yield stress) may be measured less than the actual stress by 10-15 percent. Third, eccentricity of hole relative to the rosette center effects on the accuracy of residual stress measurements by 10 percent. The error due to eccentricity of hole can be corrected by the iteration method or the direct method.