• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.304-307
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• 2002

High speed machining was accomplished. through the technological advances which covers the whole field of mechanical industry. But tapping have many troubles because of its complicate cutting mechanism, for example. tool damage, chip elimination and synchronization between spindle rotation and feed motion. But High speed tapping is so important that it marches in step with the flow of the times and make improvement in the productivity. In this paper we analyze mechanism of high speed synchronized tapping with the signal of tapping torque and spindle speed obtained through the newly developed high speed tapping machine(NTT-30B). We made an experiment with this machine on condition of various speed from 1000rpm to 10000rpm. As one complete thread is performed through the whole chamfer cutting, cutting torque increases highly in chamfer cutting, but smoothly in full thread cutting functioning of the threads guide. And the size of cutting torque according to spindle speed(rpm) was not enough of a difference to be conspicuous.

• Korean Journal of Environmental Biology
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• v.20 no.1
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• pp.35-39
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• 2002

The significance of cell ploidy and repair ability for the radioprotective efficiency of cysteamine was studied in DNA repair - proficient and repair - deficient yeast cells irradiated $^{60}C0\;\gamma-rays.$ Results have been obtained for the cell survival of two groups of yeasts-diplont and haplont cells, both in haploid and diploid states. For diploid Saccharomyces cerevisiae yeast cells, the correlation between the radio-protective action of cysteamine and the cell repair capacity was demonstrated. Such a correlation was not clearly expressed for haploid yeast cells. In addition, evidence was obtained indicating that the degree of the radioprotective action was independent of the number of chromosome sets in haplont yeast Pichia guilliermondii cells and in some radiosensitive mutants defective in the diploid-specific recovery. It is concluded on this basis that the radioprotective action may involve the cellular recovery process, which may be mediated by a recombination-like mechanism, for which the diploid state is required. The results obtained clearly show that the radioprotective effect was dependent on DNA repair status and indicate that the mechanism of the radioprotective action may be realized on the level of primary radiation damage production as well as on the level of postradiation recovery from potentially lethal radiation damage.

• Proceedings of the Botanical Society of Korea Conference
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• 1999.07a
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• pp.79-84
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• 1999

Oxidative stress is one of the major environmental stresses to plants. Reactive oxygen species (ROS) generated during metabolic processes damage cellular functions and consequently lead to cell death. Fortunately plants have in vivo defense system by which the ROS is scavenged by enzymes such as superoxide dismutase (SOD) and ascorbate peroxidase (APX). In attempts to understand the protection mechanism of plant against oxidative stress, we developed transgenic tobacco (Nicotiana tabacum cv. Xanthi) plansts thet expressed both SOD and APX in chloroplast using Agrobacterum-mediated transformation and evaluated their protection capabilities against methyl viologen (MV, paraquat) -mediated oxidative damage. Three double transformants (CAI, CA2, and CA3) expressed the chimeric CuZnSOD and chimeric APX in chloroplast, and one transformant (AM) expressed the chimeric APX and chimeric MnSOD in chloroplast. In addition, we obtained three lines of transformants (C/Al, C/A2, and A/C) that expressed the APX and SOD than control plants, and more resistant to oxidative stress caused by MV. TRansformants (C/A and A/C) overexpressing MnSOD, CuZnSOD and APX at the same time showed the highest resistance to MV-mediated oxidative stress among the transformants.

• Composites Research
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• v.13 no.4
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• pp.1-10
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• 2000

SiC particulate reinforced metal matrix composites(MMCs) are emerging as candidate materials for the automobile and aerospace industries due to their significant increase in elastic modulus and strength compared to conventional metallic materials. However, in order to make successful application of MMCs, it is very important to understand micro-failure mechanism under cyclic loading because failure mechanism of MMC is dominated by accumulation of micro-failure due to applied loading. In this study, ultrasonic Lamb wave and acoustic emission(AE) have been used to monitor microscopic damage accumulation under cyclic loading for SiC particulate reinforced metal matrix composite(SiCp/A356). It was found that the change in velocity and attenuation of ultrasonic Lamb wave due to the increase of loading cycles could be characterized by three different stages corresponding to the microscopic fracture processes. The characteristic of AE signal at each stage was analyzed and discussed by comparing with the change of ultrasonic characteristic in MMCs.

• Earthquakes and Structures
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• v.13 no.2
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• pp.211-220
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• 2017

Observations from past strong earthquakes revealed that near-fault ground motions could lead to the failure, or even collapse of electricity transmission towers which are vital components of an overhead electric power delivery system. For assessing the performance and robustness, a high-fidelity three-dimension finite element model of a long span transmission tower-line system is established with the consideration of geometric nonlinearity and material nonlinearity. In the numerical model, the Tian-Ma-Qu material model is utilized to capture the nonlinear behaviours of structural members, and the cumulative damage D is defined as an index to identify the failure of members. Consequently, incremental dynamic analyses (IDAs) are conducted to study the collapse fragility, damage positions, collapse margin ratio (CMR) and dynamic robustness of the transmission towers by using twenty near-fault ground motions selected from PEER. Based on the bending and shear deformation of structures, the collapse mechanism of electricity transmission towers subjected to Chi-Chi earthquake is investigated. This research can serve as a reference for the performance of large span transmission tower line system subjected to near-fault ground motions.

• Herbal Formula Science
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• v.30 no.4
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• pp.225-231
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• 2022

Objectives : Oxidative damage has a variety of mechanism in the human organs including brain and liver. The purpose of this study is to examine the prevention against cellular damage, and the inhibitory effect on lipogenesis of the water extract of Eriobotrya japonica (EJE). Methods : The effect of EJE on cell viability was assessed using the MTT assay. To investigate the mechanism of EJE's inhibition of lipogenesis, we analyzed the relevant proteins using immunoblot analysis. Results : Induction of T0901317, a LXR agonist, significantly increased SREBP-1c expression, which was blocked by the pretreatment of EJE in the dose-dependent manners. This beneficial herb also regulated the genes related with SREBP-1c such as the acetyl-CoA carboxylase. Conclusion : These results suggested that EJE might have a possibility of the treatment of chronic diseases as mediated with the inhibition of LXRα/SREBP-1c pathway.

• Journal of Korean Medical classics
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• v.36 no.3
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• pp.27-54
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• 2023

Objectives : To determine the background against which Zhishi has been applied to treat Pi pattern, through examination of changes in Pi pattern treatments in a historical context. Methods : The properties and nature of Zhishi as written in multiple bencao texts were analyzed. In addition, understanding of the Pi pattern, the changes in its treatment were examined diachronically based on opinions of Zhang Zhongjing, Zhugong, and Li Dongyuan. Examples of Zhishi application in Pi pattern treating formulas were collected and their mechanisms analyzed. Results : Zhishi is strongly effective in relieving accumulation and stagnation, due to its properties of dispersing and lowering. The early view of contrasting Pi with Jiexiong shifted to viewing the Pi pattern as an inner damage, from the perspective of rising and lowering of the Qi mechanism based on the Spleen and Stomach. As a result, Zhishi became a key ingredient in the treatment of the Pi pattern. Conclusions : As the perspective of seeing Pi as one end of the Yin-Yang coupling with Jiexiong from the Shanghanlun shifted to seeing it as a problem of Qi mechanism of the Spleen and Stomach, Zhishi became a key ingredient in the formulas to treat Pi pattern. The complexity of Zhishi's direction made it appropriate to treat the changed Pi pattern.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.489-497
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• 2000

Since Chinese cabbages weigh 3 to 5kgf and are big in size at the time of harvest, handling operations such as harvesting, loading and unloading including transportation require the highest labor demand among all other cultivation processes. Recently, though several cabbage harvesters were developed in Japan and Europe, those harvesters were not suitable for Chinese cabbages cultivated in Korea because of the size and shape. The cabbage harvester is almost meaningless without any proper cabbage piling and pallet unloading mechanism. Most harvesters developed so far adopted a sort of slide and free falling way in collecting cabbages into the pallet. Three or four labors are usually required for cleaning incoming cabbages and loading those in the pallet. Because of the required time for piling cabbages without severe damage and the required space capacity to carry empty and loaded pallets, harvesting speed should be adjusted in accordance with time required for consecutive operations. Up to now, any automatic or semi-automatic collecting device has not been developed in the world to pile cabbages on the layer one by one into the pallet in the ordered way with little damage and to unload pallet from the harvester continuously during the harvest process. To compromise system expenses and function, Semi-automatic cabbage piling and pallet unloading mechanism was devised and it required one labor. The foldable mesh pallet with a size of 1050mm x 1050mm x 1000mm and holding capacity of around 70 cabbages was utilized. The prototype for piling and unloading mechanism was composed of three parts such as feeding device, automatic piling device with retractable bellows, and pallet unloading device. Prior to developing the prototype, the geometric properties and the amount of the damage of the cabbage caused during the piling operation were investigated. Considering the height of the pallet, a series of cabbage carrying plates were mounted to the bracket chain to lift and to carry cabbages to the loading device. Indoor laboratory experiments showed that the cabbage carrying chain conveyor worked successfully. Considering the conveying speed 0.46m/sec of the pull up belt from the cabbages on the ground, the speed of cabbage carrying chain conveyor worked property in the range of 0.26m/sec to 0.36m/sec. The system allowed the operator to modify the position of cabbage slightly. Overall system worked successfully resulting into almost same capacity without severe damage to the cabbage as human did.

• The Korean Journal of Air & Space Law and Policy
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• v.23 no.1
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• pp.33-54
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• 2008

The damage to the third parties caused by aircraft in flight shall be fully compensated to the extent that the damage didn't occur unless the damage is caused by innocent victims. However, related international Conventions limit operator's liability of compensation to certain levels, which is one of the main reasons that such international Conventions have not been ratified by many aviation leading States. However, international community has agreed, since 9/11, that the accidents caused by terrorists and the protection of the third parties need to be addressed more actively. And the amendment of the related Rome Conventions has been drafted under the ICAO leadership by the special committee that was organized to modernize the related international Conventions. This study addresses the issues related to the draft Conventions, the draft Convention for Damage caused by Aircraft to Third Parties, in case of Unlawful Interference and the draft Convention on compensation for Damage caused by Aircraft to Third Parties. It is expected that it takes considerable time to reach an agreement on all the issues from appropriate apportionment of liability between the government and operator to the details regarding the management of Supplementary Compensation Mechanism. Under the circumstances where the needs for the air transportation as well as threats of terrorism increase, the new international Convention should be prepared taking into consideration the balance between the protection of the innocent third parties and that of air transport industry including air carriers. Along with this, the Republic of Korea should actively participate in the process of amendment to the related international Conventions to protect the life and property of the people from anticipated damages.

• The Journal of Korean Medicine
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• v.26 no.4
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• pp.39-45
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• 2005

Objectives: The study investigated the efficacy of oral Korean red-ginseng (RG) on sCRP response mediated by eccentric contraction-induced muscle damage and discussed its mechanism. Methods: Nineteen healthy young subjects (aged 24.4$\pm$2.07 yr) volunteered for this double blind test. They were classified into either the RG group (N=10) or placebo (P) group (N=9) during the 10-d experimental protocol. Blood samples were collected on T1 (baseline), T1 (1h), T2 (1d), T3 (2d) and T4 (3d) after eccentric contraction-induced injury on the seventh day. Statistical analyses were conducted using nonparametric methods (p<0.05). Results: The RG group increased sCRP more than P group and didn't increase soreness peak at T2, not significant. There were no correlations between soreness intensity and sCRP. Oral RG had little efficacy for reducing sCRP at the muscle damage-mediated acute phase; rather, it increased because of its proinflammatory cytokine production. Conclusions: Oral RG could stimulate proinflammatory cytokine production, and occasionally bal-pyo-beob could be helpful for the efficient recovery of muscle injury.