• Journal of the Korean Society for Heat Treatment
• /
• v.11 no.2
• /
• pp.92-98
• /
• 1998

Degradation and recovery of damping capacity in a Cu-65%Mn alloy have been studied. When the alloy was isothermally aged at $400^{\circ}C$, the highest damping capacity was observed after aging for 4 hours. In case when the alloy aged at $400^{\circ}C$ for 4 hours was maintained at $100^{\circ}C$, the damping capacity gradually decreased with time. The microstructural observations showed that the formation of subdomains and ${\alpha}$-Mn precipitates are responsible for the degradation of damping capacity. When the degraded specimen was reheated at $250^{\circ}C$ for 30 minutes, the damping capacity was recovered considerably owing to the redistribution of impurity atoms, the extinction of subdomains and the release of damping sources from ${\alpha}$-Mn precipitates during the repeated transformation, fcc${\leftrightarrow}$fct.

• The korean journal of orthodontics
• /
• v.19 no.2
• /
• pp.75-84
• /
• 1989

The purpose of this experiment was to measure the amounts of nickel and chromium released from a simulated orthodontic appliance in artificial saliva. Simulated mandibular half-arch orthodontic appliances were composed of American Iron and Steel Institute type 304 brackets, Permachrome, Elgiloy, Australian wire, T.M.A. and Nitinol. The amounts of nickel and chromium released from sample were measured with atomic absorption spectrophotometer after 3, 6, 9, 12, 15 days. The cumulative amounts of nickel released from Permachrome, Elgiloy, Australian wire and T.M.A. reached a plateau after 6 days. But the cumulative amounts of nickel released from Nitinol increased continuously. Significant amounts of both nickel and chromium were solubilized from the simulated orthodontic appliances into artificial saliva. After 15 days, total cumulative amounts of nickel were $152.15{\mu}g$, $150.27{\mu}g$, $134.74{\mu}g$, $114.67{\mu}g$ and $93.39{\mu}$ from the Elgiloy, Australian wire, Nitinol, Permachrome and T.M.A., respectively. Total cumulative amounts of chromium from Permachrome, Australian wire, Elgiloy, Nitinol and T.M.A. were $100.83{\mu}g$, $83.64{\mu}g$, $81.61{\mu}g$, $14.90{\mu}g$ and $12.43{\mu}g$, respectively. The result showed that nickel released from Elgiloy and chromium released from Permachrome were more than any others.

• Journal of Electrochemical Science and Technology
• /
• v.9 no.2
• /
• pp.85-92
• /
• 2018

Olivine structure of $LiFePO_4$ (LFP) is one of the most commonly used materials in aqueous rechargeable lithium batteries (ARLBs), and can store and release charge through the insertion/de-insertion of $Li^+$ between LFP and FP. We have fabricated LFP and LFP/FP electrodes on titanium paper and studied their electrochemical properties in 2 M $Li_2SO_4$. The LFP/FP electrode was determined to be a suitable electrode for electo-ostmotic pump (EOP) in terms of efficiency in water and 0.5 mM $Li_2SO_4$ solution. Experiments to determine the effect of cations and anions on the performance of EOP using LFP/FP electrode have shown that $Li^+$ is the best cation and that the anion does not significantly affect the performance of the EOP. As the concentration of $Li_2SO_4$ solution was increased, the current increased. The flow rate peaked at $4.8{\mu}L/30s$ in 1.0 mM $Li_2SO_4$ solution and then decreased. When the EOP was tested continuously in 1.0 mM $Li_2SO_4$ solution, the EOP transported approximately 35 mL of fluid while maintaining a stable flow rate and current for 144 h.

• BMB Reports
• /
• v.35 no.1
• /
• pp.127-133
• /
• 2002

Nitrosative stress can prevent or induce apoptosis. It occurs via S-nitrosylation by the interaction of nitric oxide (NO) with the biological thiols of proteins. Cellular redox potential and non-heme iron content determine S-nitrosylation. Apoptotic cell death is inhibited by S-nitrosylation of the redox-sensitive thiol in the catalytic site of caspase family proteases, which play an essential role in the apoptotic signal cascade. Nitrosative stress can also promote apoptosis by the activation of mitochondrial apoptotic pathways, such as the release of cytochrome c, an apoptosis-inducing factor, and endonuclease G from mitochondria, as well as the suppression of NF-${\kappa}B$ activity. In this article we reviewed the mechanisms whereby S-nitrosylation and nitrosative stress regulate the apoptotic signal cascade.

• The Journal of Korean Medicine
• /
• v.26 no.3 s.63
• /
• pp.162-175
• /
• 2005

Backgrounds : Two stress pathways, the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system, regulate immune system responses through release of corticosteroids, norepinephrine and epinephrine. respectively. These neuromediators act on immune cells via specific receptors on their surface to modulate the production of key regulatory cytokines. Objectives : To evaluate the preventive effects of oriental medicine Hyeolbuchukyeo-tang (HC) on stress. Methods : Mice were divided into three groups: nounal group, control group under immobilization stress and HC group which received Hyeolbuchukyeo-tang (HC) under immobilization stress. following sacrifice, their splenocytes were isolated and splenocyte surface markers were determined. The brains were removed and mRNA determined. In vivo, we separated RNA Iron cultured macrophages (RAW264.7). Results : In our study, immune functions were decreased in stress due mainly to changes of various neuromediators, cytokines and macrophage activities, and the treatment of HC increased those expressions. Conclusions : In summary, the present study documents the anti-stress effects of HC through stress-immune regulation.

• Nuclear Engineering and Technology
• /
• v.53 no.3
• /
• pp.833-841
• /
• 2021

During the postulated severe accident of nuclear reactor, eutectic reaction leads to low-temperature melting of fuel cladding and early failure of core structure. In order to model eutectic melting with the moving particle semi-implicit (MPS) method, the eutectic reaction model is developed to simulate the eutectic reaction phenomenon. The coupling of mass diffusion and phase diagram is applied to calculate the eutectic reaction with the uniform temperature. A heat transfer formula is proposed based on the phase diagram to handle the heat release or absorption during the process of eutectic reaction, and it can combine with mass diffusion and phase diagram to describe the eutectic reaction with temperature variation. The heat transfer formula is verified by the one-dimensional melting simulations and the predicted interface position agrees well with the theoretical solution. In order to verify the eutectic reaction models, the eutectic reaction of uranium and iron in two semi-infinite domains is simulated, and the profile of solid thickness decrease over time follows the parabolic law. The modified MPS method is applied to calculate Transient Reactor Test Facility (TREAT) experiment, the penetration rate in the simulations are agreeable with the experiment results. In addition, a hypothetical case based on the TREAT experiment is also conducted to validate the eutectic reaction with temperature variation, the results present continuity with the simulations of TREAT experiment. Thus the improved method is proved to be capable of simulating the eutectic reaction in the severe accident.

• Tuberculosis and Respiratory Diseases
• /
• v.72 no.2
• /
• pp.163-168
• /
• 2012

Background: Cigarette smoke induced release of iron could alter iron metabolism in the lungs of chronic smokers and contribute to the increase in the total oxidative burden on the lungs of smokers. In previous studies, ferritin levels of bronchoalveolar lavage fluid in smokers were elevated. The aim of the present study was to investigate the relationship between serum ferritin concentration, smoking and lung function in Korean people. Methods: This study was based on the data acquired in the second year (2008) of the Forth National Health and Nutrition Examination Survey that was conducted from 2007 to 2009. The analysis included 2,244 subjects who were older than 20 years and had complete data from both lung function test and serum ferritin concentration. Among participants, 1,076 were male and 1,168 were female. Results: Mean serum ferritin concentrations in males were $120.3{\pm}80.1{\mu}g/L$ and $47.9{\pm}39.8{\mu}g/L$ in females. There were no differences in serum ferritin concentrations between non-smokers and smokers after adjusting for age, body mass index, and amounts of alcohol. Serum ferritin concentrations were associated with smoking amounts by simple linear regression but not associated with smoking amounts after adjustment with age, body mass index, and amounts of alcohol in both males and females. Lung function was not associated with serum ferritin concentrations. Conclusion: Our data suggested that serum ferritin concentrations are not related with smoking and lung function.

• Economic and Environmental Geology
• /
• v.33 no.2
• /
• pp.91-100
• /
• 2000

It has been more than ten years since Dukun mine was abandoned. Tailings of waste deposits and slime dumps in the abandoned Dukum mine have been left to be deserted for fifty years. The results of fifty years of neglecting are nothing short of major environmental problems. Slime dumps have been exposed to air and water in the mine over ten years and then soil profile has been formed well. Soil in the upper layer (A horizon) is the light gray color due to the leaching of cations. Soil in the lower layer (A2 horizon, 0.2∼0.3m)is tinted with reddish brown and yellowish brown color due to the development of iron oxides and iron hydroxides. Soil in the lower part of B horizon of (1.0∼3.0m) with the growth of copper and zinc oxides exposes to the bluish green, light blue, and dark gray. Ranging from 3m to 8m in depth, 85 samples were taken from 22 sampling sites with 50m intervals located on the slime dump area with hand auger and trench (open cut). As tailings was distributed, heavy metal elements extracted by the process of surface water and ground water move and disperse in to the hydrosphere. Waste dumps were distributed in and around the mine and water draining from those dumps be a potential source of contamination. Soils, thus, can be dispersed into downslope and downstream through wind and water by clastic movement. These materials may be deposited in another horizon if the water is withdrawn, or if the materials are precipitated as a result of differences in pH, or other conditions in deeper horizons. These were primarily associated with acid mine drainage. The characteristics and rate of release of acid mine drainage are influenced by various chemical and biological reactions at the source of acid generations. Prolonged extration of heavy metal elements has a detrimental effect on the agricultural land and residental area. Twenty soil samples were collected from the agricultural land in the area (0∼30 cm). Seventeen samples were also taken from the sediment in the stream running alongside the dumps. The dispersion patterns of heavy metal elements are as follows: The content of As ranged 2∼6 ppm in a horizon, 20∼125 ppm in B horizon with large amount of clay mineral is concentrated and the content of Cd ranged 1∼2 ppm in A horizon, 4∼22 ppm in B horizon. Like Cd, the content of As, Cu, Zn, Pb in B horizon is higher than that in A horizon (approximately 5∼100 times). When soil formation proceeds in stages, it is necessary to investicate the B horizon with the concentration of heavy metal and preventive measures will have to established.

• Journal of Korean Society of Environmental Engineers
• /
• v.38 no.1
• /
• pp.1-7
• /
• 2016

In order to treat electrolysis nickel plating pickling wastewater to meet the effluent limit less than 3.0 mg/L, the electrolysis process by using soluble and insoluble electrode were studied. Electrolysis using soluble electrodes has a characteristic of easy elution from the electrode which the insoluble electrodes close not release metal from the electrode. For these reasons, there exist different characteristics in nickel removal efficiency, purity of nickel sludge. With this connection, the feasibility test were concluded to develop optimal conditions for the treatment of pickling wastewater electrolysis by using soluble electrodes, insoluble electrodes. Optimal condition of current density, pH were derived from the pickling wastewater using insoluble electrodes. It was concluded the highest removal efficiency of nickel at the operation condition of at pH 9, current density of $15mA/cm^2$. At these conditions, 95.3% purity of nickel sludge was achieved, iron content was 2.9%. Optimal condition when using soluble electrodes was derived current density of $10mA/cm^2$, pH 9. Purity of nickel sludge was 77.3%, iron content was 21.0%. 50.7% and 24.2% of operating cost can be saved by the use of soluble electrodes and the use of insoluble electrodes, respectively.

• Korean Journal of Food Science and Technology
• /
• v.27 no.5
• /
• pp.742-747
• /
• 1995

The effect of storage temperature and period on the contents of tin, iron, lead and vitamin C, browning index and pH was studied for canned and bottled orange juices currently sold in Korean market, which were stored for 24 weeks at 20, 30, 40 and $50^{\circ}C$ and analyzed at 4 week intervals. The change of metal content in bottled juices was negligible but metal release in canned juices was remarkably affected by storage temperature. Tin content after 16 weeks increased by $2.7{\sim}13.1$ times, iron content after 24 weeks increased by $4.3{\sim}5.2$ times and lead content after 24 weeks increased by $1.1{\sim}2.9$ times. Retention of total ascorbic acid in canned juices after 24 weeks at $30{\sim}50^{\circ}$ decreased to $13{\sim}76%$, while that in bottled juices decreased to $4{\sim}80%$. Browning index in canned juices after 24 weeks below $40^{\circ}C$ increased slightly with serious discoloration at $50^{\circ}C$ while that in bottled juices increased a little rapid. pH change in canned and bottled juices during storage below $40^{\circ}C$ was not observed regardless of container type but a great change of pH was accompanied with swelling of container ends in the case of canned juices after 24 weeks at $50^{\circ}C$.