• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1033-1039
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• 2012

Artificial joints are used when joints lose their function because of either the destruction or damage of the composing bones of the joints. To evaluate the primary stability of a femur-implant system, the relative displacement caused by a repeated load is measured immediately after the insertion of the artificial joint. For more accurate stability evaluation, the accurate measurement of the penetration displacement of the artificial joint to the bone and the rotation angle of the artificial joint is essential. In this study, to evaluate the primary stability of the femur-implant system, we propose a new relative displacement measurement method. By using this new method, we comparatively evaluate the primary stability for various surgical methods and the varying stiffness of the cadaver femur-implant itself.

• Molecules and Cells
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• v.46 no.8
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• pp.496-512
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• 2023

A fructose-enriched diet is thought to contribute to hepatic injury in developing non-alcoholic steatohepatitis (NASH). However, the cellular mechanism of fructose-induced hepatic damage remains poorly understood. This study aimed to determine whether fructose induces cell death in primary hepatocytes, and if so, to establish the underlying cellular mechanisms. Our results revealed that treatment with high fructose concentrations for 48 h induced mitochondria-mediated apoptotic death in mouse primary hepatocytes (MPHs). Endoplasmic reticulum stress responses were involved in fructose-induced death as the levels of phosho-eIF2α, phospho-C-Jun-N-terminal kinase (JNK), and C/EBP homologous protein (CHOP) increased, and a chemical chaperone tauroursodeoxycholic acid (TUDCA) prevented cell death. The impaired oxidation metabolism of fatty acids was also possibly involved in the fructose-induced toxicity as treatment with an AMP-activated kinase (AMPK) activator and a PPAR-α agonist significantly protected against fructose-induced death, while carnitine palmitoyl transferase I inhibitor exacerbated the toxicity. However, uric acid-mediated toxicity was not involved in fructose-induced death as uric acid was not toxic to MPHs, and the inhibition of xanthine oxidase (a key enzyme in uric acid synthesis) did not affect cell death. On the other hand, treatment with inhibitors of the nicotinamide adenine dinucleotide (NAD)⁺-consuming enzyme CD38 or CD38 gene knockdown significantly protected against fructose-induced toxicity in MPHs, and fructose treatment increased CD38 levels. These data suggest that CD38 upregulation plays a role in hepatic injury in the fructose-enriched diet-mediated NASH. Thus, CD38 inhibition may be a promising therapeutic strategy to prevent fructose-enriched diet-mediated NASH.

• Tuberculosis and Respiratory Diseases
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• v.51 no.2
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• pp.97-107
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• 2001

Background : Tuberculosis itself causes not only lung parenchymal destruction but also pulmonary vascular damage. Secondary emphysema also causes pulmonary vascular damage, which can develop as a late sequela of pulmonary tuberculosis. Therefore, pulmonary circulatory impairment tends to be more severe in post-tuberculosis emphysema than in primary emphysema. In post-tuberculosis emphysema, the right ventricular function may play an important role. However, little information regarding the right ventricular function is available. The purpose of this study was to evaluate and compare the right ventricular function between post-tuberculosis emphysema and primary emphysema. Method: Post-tuberculosis emphysema(PTE) or primary emphysema(PE) was diagnosed by history, HRCT finding and pulmonary function. Twenty patients with post-tuberculosis emphysema were matched with 20 patients with primary emphysema according to both $FEV-1$ and FVC. Arterial blood gas analysis and echocardiography were done at rest and immediately after symptom-limited exercise. The right ventricular function was evaluated with the right ventricular ejection fraction using a modification of Simpson's method. Results : There was no significant difference in the demographics and pulmonary function between the two groups. In post-tuberculosis emphysema, the $PaCO_2$ was higher ($42.9{\pm}4.7$ vs $38.8{\pm}3.1\;mmHg$ at rest; $47.9{\pm}7.0$ vs $41.1{\pm}5.9\;mmHg$ after exercise; p<0.01) and the right ventricular ejection fraction was lower ($57.6{\pm}6.5$ vs $61.4{\pm}4.7%$ at rest; $51.1{\pm}10.8$ vs $59.8{\pm}6.6%$ after exercise; p<0.01) both at rest and after exercise. The $PaCO_2$ after exercise was also lower ($65.7{\pm}12.6$ vs $80.2{\pm}14.4\;mmHg$, p<0.01), while the Pa02 at rest tended to be lower($82.9{\pm}12.0$ vs $87.8{\pm}7.5$, p>0.05). In both groups, right ventricular ejection fraction correlated with the $PaCO_2$ after exercise(PTE r=0.536, PE r=0.557), and the $PaCO_2$ at rest(PTE r=-0.576, PE r=-0.588) and after exercise(PTE r=-0.764, PE r=-0.619). Conclusion : Impairment of the right heart function and gas exchange were more serious in post-tuberculosis emphysema than in primary emphysema, and gas exchange may be influenced by the right ventricular function in post-tuberculosis emphysema.

• Journal of Life Science
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• v.23 no.8
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• pp.963-969
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• 2013

Although it is popularly believed that vitamin C protects cells from various genotoxicants, the degrees and mechanisms of itsprotective actions are not fully understood. In this study, vitamin C's protective effects against various genotoxicants were quantified, together with subsequent analyses on the mechanisms of these protective effects. Comet assay was employed to measure the degree of DNA damage in Chinese hamster ovary cells (CHO-K1) exposed to five genotoxicants, $H_2O_2$, $HgCl_2$, N-methyl-N-nitro-N-nitrosoguanidine (MNNG), 4-nitroquinoline-1-oxide (4NQO), and UV-irradiation. In cases cells were treated with $H_2O_2$, $HgCl_2$, and 4NQO together with vitamin C, the damage to DNA decreased to the level of the control group. In cases of UV-irradiation, the protective effect of vitamin C appeared, but did not reach the control levels. Interestingly, vitamin C did not have protective effects against the genotoxicity of MNNG. The degrees of DNA damage of cells treated with vitamin C prior to exposure togenotoxicants were 28~49% lower than those of cells treated with vitamin C after being exposed to genotoxicants. In conclusion, vitamin C had strong antioxidanteffects against genotoxicants by being a primary antioxidant blocking genotoxicity reaching the cells, rather than being a secondary antioxidant acting on post-exposure DNA repair processes. However, vitamin C's protective effects appearto be limited, as there are genotoxicants, such as MNNG, whosegenotoxicityis not affected by vitamin C. Therefore, the results of this study warrant furtherstudies on toxic mechanisms of genotoxicants and their interactions with protective mechanisms of vitamin C.

• International Journal of Automotive Technology
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• v.4 no.2
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• pp.77-86
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• 2003

How to compare the environmental damage caused by vehicles with different foe]s and drive trains\ulcorner This paper describes a methodology to assess the environmental impact of vehicles, using different approaches, and evaluating their benefits and limitations. Rating systems are analysed as tools to compare the environmental impact of vehicles, allowing decision makers to dedicate their financial and non-financial policies and support measures in function of the ecological damage. The paper is based on the "Clean Vehicles" research project, commissioned by the Brussels Capital Region via the BIM-IBGE (Brussels Institute for the Conservation of the Environment) (Van Mierlo et at., 2001). The VriJe Universiteit Brussel (ETEC) and the universite Libre do Bruxelles (CEESE) have jointly carried out the workprogramme. The most important results of this project are illustrated in this paper. First an overview of environmental, economical and technical characteristics of the different alternative fuels and drive trains is given. Afterward the basic principles to identify the environmental impact of cars are described. An outline of the considered emissions and their environmental impact leads to the definition of the calculation method, named Ecoscore. A rather simple and pragmatic approach would be stating that all alternative fuelled vehicles (LPG, CNG, EV, HEV, etc.) can be considered as ′clean′. Another basic approach is considering as ′clean′ all vehicles satisfying a stringent omission regulation like EURO IV or EEV. Such approaches however don′t tell anything about the real environmental damage of the vehicles. In the paper we describe "how should the environmental impact of vehicles be defined\ulcorner", including parameters affecting the emissions of vehicles and their influence on human beings and on the environment and "how could it be defined \ulcorner", taking into account the availability of accurate and reliable data. We take into account different damages (acid rain, photochemical air pollution, global warming. noise, etc.) and their impacts on several receptors like human beings (e.g., cancer, respiratory diseases, etc), ecosystems, or buildings. The presented methodology is based on a kind of Life Cycle Assessment (LCA) in which the contribution of all emissions to a certain damage are considered (e.g. using Exposure-Response damage function). The emissions will include oil extraction, transportation refinery, electricity production, distribution, (Well-to-Wheel approach), as well as the emission due to the production, use and dismantling of the vehicle (Cradle-to-Grave approach). The different damages will be normalized to be able to make a comparison. Hence a reference value (determined by the reference vehicle chosen) will be defined as a target value (the normalized value will thus measure a kind of Distance to Target). The contribution of the different normalized damages to a single value "Ecoscore" will be based on a panel weighting method. Some examples of the calculation of the Ecoscore for different alternative fuels and drive trains will be calculated as an illustration of the methodology.

• Parasites, Hosts and Diseases
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• v.33 no.1
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• pp.37-44
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• 1995

Neodiplostomum seoulensis, one of the human intestinal trematodes , was reinfected to albino rats, and worm recovery rates, histopathology and activity changes of the intestinal brush border membrane bound enzymes were observed. The experimental groups were three: uninfected, primary infection and reinfection. The worm recovery rate in the reinfection group was much lower than in the primary infection group 14 days after infection. The duodenal histopathology showed villous atrophy during the first and second week in the primary infection group. In the reinfection group, however. villous changes occurred as early as 3 days after the infection, and the lesion was found healed 7 days after infection. The activities of alkaline phosphatase and sucrase in the duodenum of primary infection rats decreased nearly half of the controls 2 weeks after infection, whereas the activities were unchanged in the reinfection group. However, no changes in the activities were observed in the proximal jejunum between the experimental groups. These findings suggested that a secondary infection of N. seouLensis in rats should make less damage on the intestinal mucosa than a primary infection. Key words: Neoniplostomum seoulensis, albino rats, reinfection, worm recovery, histopathology, brush border membrane bound enxyines.

• Journal of Radiation Protection and Research
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• v.30 no.2
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• pp.69-75
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• 2005

Gas avalanche microdetectors, such as micro-strip gas chamber (MSGC), micro-gap chamber (MGC), micro-dot chamber (MDOT), etc., are operated under high voltage to induce large electron avalanche signal around micro-size anodes. Therefore, the anodes are highly exposed to electrical damage, for example, sparking because of the interaction between high electric field strength and charge multiplication around the anodes. Gas electron multiplier (GEM) is a charge preamplifying device in which charge multiplication can be confined, so that it makes that the charge multiplication region can be separate from the readout micro-anodes in 9as avalanche microdetectors possible. Primary electron collection efficiency is an important measure for the GEM performance. We have defined that the primary electron collection efficiency is the fractional number of electron trajectories reaching to the collection plane from the drift plane through the GEM holes. The electron trajectories were estimated based on 3-dimensional (3D) finite element method (FEM). In this paper, we present the primary electron collection efficiency with respect to various GEM operation parameters. This simulation work will be very useful for the better design of the GEM.

• Nuclear Engineering and Technology
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• v.44 no.3
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• pp.331-342
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• 2012

Since the opening of the Shin-Kori #1,2 in 2005, fly ash mixed concrete has been used for NPP concrete structures under construction in Korea with the aim of preventing aging and improving durability. In this paper, the quality suitability of fly ash manufactured in Korea is assessed and the basic physical properties of fly ash mixed concrete and its durability against primary causes of aging are verified through experimental methods. Because of the internal structure filling effect from the pozzolanic reaction of fly ash and the resulting improvements in mechanical performance in such areas as strength and salt damage resistance, the durability of fly ash mixed concrete is shown to be superior. It is judged that this result can be applied in measures not only for improving the safety of NPP structures in operation in Korea but also for implementing effective structure life management should extending the life of structures be needed in the future.

• Journal of the Korean Society for Nondestructive Testing
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• v.9 no.1
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• pp.106-110
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• 1989

Bolting degradation problems in primary coolant pressure boundary applications have become a major concern in the nuclear industry. In the bolts concerned, the failure mechanism was either corrosion wastage(loss of bolt diameter) or stress-corrosion cracking.(3) Here the manual ultrasonic testing of RPV(Reactor Pressure Vessel) and RCP(Reactor Coolant Pump) stud has been performed. But it is difficult to detect indications because examiner can not exactly control the rotation angle and can not distinguish the indication from signals of bolt. In many cases, the critical sizes of damage depth are very small(1-2 mm order). At critical size, the crack tends to propagatecompletly through the bolt under stress, Resulting in total fracture.(3) Automatic stud scanner for studs(bolts) was developed because the precise measurement of bolt diameter is required in this circumstance. By use of this scanner, the rotation angle of probe was exactly controlled and the exposure time of radiations was reduced.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.871-876
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• 2001

Recent earthquakes in California and Japan caused extensive damage to highway bridge structures. It is also thought that during probable earthquakes bridge structures in Korea could be failed due to the structural deficiencies, which were nonseismically designed and constructed before 1992. In these regards, innovative strengthening methods have been developed to repair reinforced concrete bridge columns, especially by glassfiber sheet bonding methods which are widely used today. The primary objective of this research is to investigate the seismic behavior of RC bridge columns retrofitted with composite straps and to propose pertinent guidelines of repair and rehabilitation method for earthquake resistant design procedure of RC bridges which are located in low or moderate seismicity regions. Six scaled-down concrete test specimens were made with test variables such as lap splice ratio, axial force ratio, confinement ratio, composite straps in the plastic hinge region. Pertinent design guidelines could be developed for the earthquake resistant design of RC bridge piers retrofitted with glassfibers in low or moderate seismic region.