• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 1994.11a
• /
• pp.21-26
• /
• 1994

Conventional electroexplosive devices (EED) commonly use a very small metal bridgewire to ignite explosive materials i.e. pyrotechnics, primary and secondary explosives. The use of semiconductor devices to replace “hot-wire” resistance heating elements in automotive safety systems pyrotechnic devices has been under development for several years. In a typical 1 amp/1 watt electroexplosive devices, ignition takes place a few milliseconds after a current pulse of at least 25 mJ is applied to the bridgewire. In contrast, as for a SCB devices, ignition takes place in a few tens of microseconds and only require approximately one-tenth the input energy of a conventional electroexplosive devices. Typically, when SCB device is driven by a short (20 $\mu\textrm{s}$), low energy pulse (less than 5 mJ), the SCB produces a hot plasma that ignites explosive materials. The advantages and disadvantages of this technology are strongly dependent upon the particular technology selected. To date, three distinct technologies have evolved, each of which utilizes a hot, silicon plasma as the pyrotechnic initiation element. These technologies are 1.) Heavily doped silicon as the resistive heating initiation mechanism, 2.) Tungsten enhanced silicon which utilizes a chemically vapor deposited layer of tungsten as the initiation element, and 3.) a junction diode, fabricated with standard CMOS processes, which creates the initial thermal environment by avalanche breakdown of the diode. This paper describes the three technologies, discusses the advantages and disadvantages of each as they apply to electroexplosive devises, and recommends a methodology for selection of the best device for a particular system environment. The important parameters in this analysis are: All-Fire energy, All-Fire voltage, response time, ease of integration with other semiconductor devices, cost (overall system cost), and reliability. The potential for significant cost savings by integrating several safety functions into the initiator makes this technology worthy of attention by the safety system designer.

• Archives of Pharmacal Research
• /
• v.28 no.7
• /
• pp.784-790
• /
• 2005

In this study, we evaluate the effects of (-)-epigallocatechin-3-gallate (EGCG) on ultraviolet B(UVB)-irradiated living skin equivalents (LSEs). Histologically, UVB irradiation induced thinning of the LSE epidermis, whereas EGCG treatment led to thickening of the epidermis. Moreover, EGCG treatment protected LSEs against damage and breakdown caused by UVB exposure. Immunohistochemically, UVB-exposed LSEs expressed p53, Fas, and 8-hydroxy-deoxyguanosine (8-OHdG), all of which are associated with apoptosis. However, EGCG treatment reduced the levels of UVB-induced apoptotic markers in the LSEs. In order to determine the signaling pathways induced by UVB, Western blot analysis was performed for both c-Jun $NH_2$-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), which are associated with UVB-induced oxidative stress. UVB activated JNK in the epidermis and dermis of the LSEs, and EGCG treatment reduced the UVB-induced phosphorylation of JNK. In addition, p38 MAPK was also found to have increased in the UVB-exposed LSEs. Also, EGCG reduced levels of the phosphorylation of UVB-induced p38 MAPK. In conclusion, pretreatment with EGCG protects against UVB irradiation via the suppression of JNK and p38 MAPK activation. Our results suggest that EGCG may be useful in the prevention of UVB-induced human skin damage, and LSEs may constitute a potential substitute for animal and human studies.

• Journal of the Korean Ceramic Society
• /
• v.48 no.5
• /
• pp.439-446
• /
• 2011

Yttria stabilized zirconia (YSZ) coating was formed on AA1050 Al alloys by aerosol deposition (AD), and its electrochemical corrosion properties were investigated in 3.5 wt% NaCl and 0.5M $H_2SO_4$ solutions. The crack-free, dense, and ~5 ${\mu}m$ thick YSZ coating was successfully obtained by AD. The as-deposited coating was composed of cubic-YSZ nanocrystallites of ~10 nm size. The potentiodynamic test indicated that the YSZ coated Al alloy had much lower corrosion current densities (2 nA/$cm^2$) by comparison to uncoated sample and exhibited a passive behavior in anodic branch. Particularly, a pitting breakdown potential could not be identified in $H_2SO_4$. EIS tests revealed that the impedance of YSZ coated sample was ${\sim}10^6{\Omega}cm^2$ in NaCl and ${\sim}10^7{\Omega}cm^2$ in $H_2SO_4$, which was about 3 or 4 orders of magnitude higher than that of uncoated sample. Consequently, the corrosion resistance of Al alloy had been significantly enhanced by the YSZ coating.

• Preventive Nutrition and Food Science
• /
• v.9 no.3
• /
• pp.253-258
• /
• 2004

Stress is a global menace exacerbated by the advancement of industrialization. Failure of stress management is to a breakdown of the psychological and physiological protection mechanisms against stress. The aim of present study was to investigate the anti-stress potential of ginseng against immobilization stress. Male Sprague-Dawley rats (n=24) were divided into three groups; (i) control, (ii) immobilization stress (2hr daily, for 2 weeks), and (iii) immobilization stress (2 hr daily, for 2 weeks) plus oral administration of ginseng (200 mg/kg BW Id). Immobilization stress resulted in a significant inhibition of body weight gain by 45 % and a significant decrease in the tissue weights of thymus and spleen (p < 0.05). The concentrations of blood GOT and GPT were significantly increased in the immobilization-stressed group compared to the control group (p < 0.05). There were no differences in the blood cholesterol levels among groups. Ginseng administration in the immobilization-stressed group tended to reverse the lack of body weight gain and food intake, though not significantly. The ginseng-administered group showed a significant reversal in the stress-induced effect on spleen and thymus weight, increasing the tissue weights by 16% and 20%, respectively, compared to immobilization-stressed group (p<0.05). The plasma corticosterone level was significantly increased in the stressed group by 39 % compared to the control group (p<0.05), but ginseng administration significantly reversed the stress-induced increase in plasma corticosterone by 15 % compared to the immobilization-stressed group. The present study suggests that the anti-stress effect of ginseng is mediated by normalization of stress-induced changes in the circulating hormones and a reversal of tissue weight loss, thereby returning the body to normal homeostasis.

• International conference on construction engineering and project management
• /
• 2013.01a
• /
• pp.634-639
• /
• 2013

The aim of the study is to develop the 3D visualization of Building Information Model and integrated 4D model for optimization of resources in the construction project. This study discuss the process of methodology and creation of 4D model of the project and simulate it to monitor the workflow at the site. Different stages of the construction process and activities are generated by using Revit and MS Project. MS project has been used for creation of the schedules and these are linked with the Revit for 3D modeling. The time used as the fourth dimension and 4D model created by using Navisworks Time liner software. Narges shopping center is presented as a case study to realize the actual uses and benefits of Building Information Model (BIM). Narges shopping mall is located in Tehran, Iran. As a part of Hekmat master plan, Narges shopping center is an 11 stores building with a total area of 30000 Sq.m. This shopping and entertainment center is comprised of 150 retails and two multi-use public halls with a capacity of 400 persons each and underground parking with total 400 parking space. The main purpose of architecture was to create an urban public center along with its revolving, spiral like form and an ever changing continuous façade by means of different colors, materials, which is in harmony with the other building of the master plan. The approximate cost of the project is $17 million and duration of the project schedule is 30 months. The developed Building Information Model enabled us to identify the potential collisions or clashes between various structural and architectural systems. 4D model has been used for limiting the interaction between subcontractors installing the different systems so rework could be avoided and productivity maximized. It is also observed that the utility of BIM for construction stimulation and clash detection is the best suitable method. Clash detection before the implementation of work is highly recommended to avoid rework.

• The Korea Journal of Herbology
• /
• v.38 no.1
• /
• pp.31-43
• /
• 2023

Objective : Alcoholic liver disease (ALD) is caused by excess alcohol intake. In the liver, alcohol breakdown results formation of toxic byproducts that lead to damage to tissue. This study is to investigate the therapeutic effects of Paeoniae Radix Alba and Puerariae Radix combination (PP) on ALD. Methods : PP was analyzed for polyphenolic compounds and free radical scavenging activity. ALD mouse model was induced by feeding ethanol and water (Control), silymarin (50 mg/kg), low-dose (PP: 100 mg/kg) or high-dose (PP: 200 mg/kg) was orally administrated to ALD mice for 14 days. The serum was assessed with levels of AST, ALT, total bilirubin, total cholesterol, and triglyceride. Liver tissues were evaluated for ROS levels, degree of liver damage and protein expression. Results : The 3:1 (Paeoniae Radix Alba:Puerariae Radix) ratio showed the best antioxidant values for the experiment. In ALD model, levels of AST, ALT, total bilirubin, total cholesterol, and triglyceride were significantly increased in the Control and the levels were decreased by treatment of PP. In addition, increased ROS, ONOO^- and MDA levels in the Control were reduced in the PP groups. Western blot analysis figured out that proteins related to ROS and cholesterol metabolism were higher in ALD than in PP-treated ALD. Antioxidant enzyme expression was low in the control group and increased by PP treatment. Conclusion : Our results suggest that PP has the potential to be a medicine in ALD in terms of regulating oxidative stress and adjusting lipid metabolism.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.30 no.2
• /
• pp.233-238
• /
• 2024

The pipe cleaning process is a crucial step in the shipbuilding process of a shipyard. It involves removing foreign substances from the inside of the pipes before moving on to the stage of testing equipment after installing the pipes. If there are foreign substances inside the pipes and the equipment is tested, the foreign substances can enter the high-priced equipment and become a factor in the breakdown of pumps, gears, bearings, and other components. Especially in the case of pumps or hydraulic valves, even small foreign substances can lead to major accidents if they enter the equipment, and such equipment accidents can be a potential cause of major disasters, leading to accidents involving workers operating the equipment in the vicinity. Therefore, it is a process that shipyard customers, who are shipowners, also focus on and manage very intensively. To solve these problems, this study developed a system that can increase the cleaning effect of the cleaning fluid inside the pipes by increasing the flow of the cleaning fluid inside the pipes in the existing pipe cleaning method.

• Horticultural Science & Technology
• /
• v.31 no.3
• /
• pp.289-298
• /
• 2013

Effects of curing treatments and storage temperature on the quality of Chinese yams (Dioscorea polystachya Turcz.) were investigated stepwise in three consecutive years for the optimization of postharvest handling procedures. Tuberous roots were harvested in early to mid November and cured under ambient or $29^{\circ}C$ heated air conditions for various periods according to the treatment conditions. Storage temperatures in the range of 0.5 to $7.5^{\circ}C$ were phased in to avoid chilling injury while examining storage potential from 4 to 7 months. As poststorage technology, short-term $60^{\circ}C$ hot-air exposure or low shelf temperature treatments were additively imposed. Curing treatments, especially heated air curing for 3-5 days tended to reduce the respiration and weight loss during storage while maintaining flesh firmness. Storage at $0.5^{\circ}C$ brought out typical chilling injury symptoms on the shelf with increases in respiration and lower flesh firmness by tissue breakdown resulting in the rapid loss of marketability. Optimum storage temperature appeared to be the $3-4^{\circ}C$ range which suppresses quality deterioration while avoiding chilling injury. Low shelf temperature seemed to be a necessary part of postharvest handling system to keep marketability through control of poststorage disorders such as rooting and decay. Overall results suggested that optimized postharvest program consisting of heated-air curing, storage at $3-4^{\circ}C$, and low shelf temperature could extend storage potential of Chinese yam to longer than 7 months.

• The Journal of Internal Korean Medicine
• /
• v.25 no.2
• /
• pp.202-213
• /
• 2004

Object : Objective: This study was conducted to investigate the anti-cancer effects of Mylabris phalerata (반모) in some kinds of cancer cells. Materials and Methods: Some kinds of cancer cells lines were treated. We used nine kinds of cancer cell lines, such as stomach cancer cells (Kato), lung cancer cells (Calu-1, NCI-H 1395), urinary bladder cancer cells (HS789T), bone cancer cells (Saos-2), brain cancer cells (SK-N-MC), liver cancer cells (Hep-G2), skin cancer cells (Mo-1) and prostate cancer cells (PC-3) with the water decoction of Mylabris phalerata. The histological changes of all cell lines in the media (RPMI-1640) containing the decoction of Mylabris phalerata were observed and we examined cell death assay by trypan blue exclusion testing was examined. Finally, the change of mitochondrial membrane potential was measurd and the inhibitory effect of Mylabris phalerata on cell increase was examined by analyzing the cell cycle. Results: In histologic change all cancer cell lines showed withdrawn and floating appearance that is typical in cellular impairment. Most of the cell lines showed over 50% death rate after 24 hours in trypan blue exclusion tests. Especially the stomach, urinary bladder. brain and liver cell lines showed over 30% death rate after 12 hours. All cell lines treated with Mylabris phalerata were less stained than the control group and the mitochondrial membrane potential in the Mylabris phalerata treated cell lines was markedly lower than that in the control group. The measurement of DNA quantity in all cell lines showed the disappearance of the peak and the thickened left axis, which suggests that all cellular DNA degraded. Conclusion: Mylabris phalerata had cytotoxicity on various kinds of cancer cell lines and the mechanism of that was the impairment of mitochondria by the breakdown of the mitochondrial cell membrane. We propose that this is in part attributable to the destruction of DNA in cancer cells.

• Journal of the Korean institute of surface engineering
• /
• v.41 no.6
• /
• pp.292-300
• /
• 2008

Dental implant system is composed of abutment, abutment screw and implant fixture connected with screw. The problems of loosening/tightening and stability of abutment screw depend on surface characteristics, like a surface roughness, coating materials and friction resistance and so on. For this reason, surface treatment of abutment screw has been remained research problem in prosthodontics. The purpose of this study was to investigate the stability of TiN and WC coated dental abutment screw, abutment screw was used, respectively, for experiment. For improving the surface characteristics, TiN and WC film coating was carried out on the abutment screw using EB-PVD and sputtering, respectively. In order to observe the coating surface of abutment screw, surfaces of specimens were characterized, using field emission scanning electron microscope(FE-SEM) and energy dispersive x-ray spectroscopy(EDS). The stability of TiN and WC coated abutment screw was evaluated by potentiodynamic, and cyclic potentiodynamic polarization method in 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. The corrosion potential of TiN coated specimen was higher than those of WC coated and non-coated abutment screw. Whereas, corrosion current density of TiN coated screws was lower than those of WC coated and non-coated abutment screw. The stability of screw decreased as following order; TiN coating, WC coating and non-coated screw. The pitting potentials of TiN and WC coated specimens were higher than that of non-coated abutment screw, but repassivation potential of WC coated specimen was lower than those of TiN coated and non-coated abutment screws due to breakdown of coated film. The degree of local ion dissolution on the surface increased in the order of TiN coated, non-coated and WC coated screws.