• Nuclear Engineering and Technology
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• 제9권2호
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• pp.75-81
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• 1977

This experiment has been carried out to determine the pH dependent cation exchange capacity concerning the sorption phenomenon of long-lived radionuclides contained in low-level liquid radioactive waste on various clay minerals. The pH dependent cation exchange capacity determined by Sawhney's method are used to the analysis of sorption phenomenon. About 70 percent of the total cation exchange capacity is contributed by the pH dependent CEC due to the negative charge originated naturally in clays in case of clinoptilolite, vermiculite and sodalite. It is sugested in this test that the high neutral salt CEC, that is, highly charged clays would show good fixation yield. The removal of radionuclides at the pH range more than pH 9 is considered the hydroxide precipitation of metal ion rather than the cation exchange. The Na-clay prepared by the method of successive isomorphic substitution with electrolyte showed a considerable improvement in removal efficiency for the decontamination.

• Journal of The Korean Astronomical Society
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• 제24권1호
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• pp.25-53
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• 1991

The evolution of the Galaxy is examined by the halo-disk model, using the time-dependent bimodal IMF and contraints such as cumulative metallicity distribution, differential metallicity distribution and PDMF of main sequence stars. The time scale of the Galactic halo formation is about 3Gyr during which the most of halo stars and metal abundance are formed and ${\sim}95%$ of the initial halo mass falls to the disk. The G-dwarf problem could be explained by the time-dependent bimodal IMF which is suppressed for low mass stars at the early phase (t < 1Gyr) of the disk evolution. However, the importance of this problem is much weakened by the Pagel's differential metallicity distribution which leads to less initial metal enrichment and many long-lived metal-poor stars with Z < $1/3Z_{\odot}$ The observational distribution of abundance ratios of C, N, O elements with respect to [Fe/H] could be reproduced by the halo-disk model, including the contribution of iron product by SNIs of intermediate mass stars. The initial enrichment of elements in the disk could be explained by the halo-disk model, resulting in the slight decrease and then the increase in the slopes of the [N/Fe]- and [C/Fe]-distributions with increasing [Fe/H] in the range of [Fe/H] < -1.

• The Korean Journal of Ceramics
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• 제2권2호
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• pp.95-101
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• 1996

Variations of the leakage current behaviors and interface potential barrier $({\Phi}_B)$ of rf-sputter deposited (Ba, Sr)$TiO_3$ (BST) thin films with thicknesses ranging from 20 nm to 150nm are investigated as a function of the thickness and bias voltages. The top and bottom electrodes are dc-sputter-deposited Pt films. ${\Phi}_B$ critically depends on the BST film deposition temperature, postannealing atmosphere and time after the annealing. The postannealing under $N_2$ atmosphere results in a high interface potential barrier height and low leakage current. Maintaining the BST capacitor in air for a long time reduces the ${\Phi}_B$ from about 2.4 eV to 1.6 eV due to the oxidation. ${\Phi}_B$ is not so dependent on the film thickness in this experimental range. The leakage conduction mechanism is very dependent on the BST film thickness; the 20 nm thick film shows tunneling current, 30 and 40 nm thick films show Shottky emission current.

• World Technopolis Review
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• 제8권1호
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• pp.21-42
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• 2019

The purpose of this research was to investigate the factors influencing global expansion/scalability of Kenyan Small and Medium Enterprises (SMEs). Factor analysis and multiple/multivariate regression analysis to determine the functional relationship between independent variables (factors) and the dependent variable was used. The independent variables were: innovation & technology, fitness/appropriateness of management, global marketing strategy; and support environment and the dependent variable, global expansion/scalability. Data was collected from a survey of randomly selected firms of 205, drawn from a population of 440 firms from Kenya Manufacturers Directory, with 175 firms responding. The key findings from the research in relation to Kenyan SMEs were that: there is a functional relationship between global market strategy and global expansion; there is a functional relationship between innovation and technology orientation and global expansion, there is no significant functional relationship between supportive environment of firms and their global expansion; and there is no significant functional relationship between fitness/appropriateness of management and global expansion/scalability. The implications for practice is that the ranking of the factors in order of priority supports focusing concern on the orientation of business strategy toward global market strategy, market research geared at obtaining foreign market intelligence, innovation and technology, product adaptation, service orientation, collaborative ventures, and long-range vision as key factors in making Kenyan firms successful in the international market. The implication for policy and practice is that there is need for collaboration between industry and government in pursuing policies for global expansion/scalability and among SMEs and large enterprises particularly in areas of rapid technological change.

• Journal of the Korean Society for Precision Engineering
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• 제19권12호
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• pp.163-170
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• 2002

The quality of a precision product, in general, relies on the accuracy and precision of its manufacturing and inspection process. In many cases, the level of precision in the manufacturing and inspection system is also dependent on the positioning capability of tool with respect to the work piece in the process. Recently the positioning accuracy level has reached to the level of submicron and long range of motion is required. For example, for 1 GDARM lithography, 20nm accuracy and 300mm stroke needs. This paper refers to the lithography stage especially to fine stage. In this study, for long stroke and high accuracy, the dual servo system is proposed. For the coarse actuator, LDM (Linear DC Motor) is used and for fine one VCM is used. In this study, we propose the new structure of VCM for the fine actuator. It is 3 axis precision positioning stage for an aligner system. After we perform the optimal design of the stage to obtain the maximum force, which is related to the acceleration of the stage to accomplish throughput of product. And we controlled this fine stage with TDC. So we obtained 50nm resolution. So later more works will be done to obtain better accuracy.

• The Korean Journal of Physiology and Pharmacology
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• 제15권5호
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• pp.291-297
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• 2011

The effect of cyclosporin A (CsA), an immunosuppressant, on human ether-a-go-go-related gene (HERG) channel as it is expressed in human embryonic kidney cells was studied using a whole-cell, patch-clamp technique. CsA inhibited the HERG channel in a concentration-dependent manner, with an $IC_{50}$ value and a Hill coefficient of $3.17{\mu}m$ and 0.89, respectively. Pretreatment with cypermethrine, a calcineurin inhibitor, had no effect on the CsA-induced inhibition of the HERG channel. The CsA-induced inhibition of HERG channels was voltage-dependent, with a steep increase over the voltage range of the channel opening. However, the inhibition exhibited voltage independence over the voltage range of fully activated channels. CsA blocked the HERG channels predominantly in the open and inactivated states rather than in the closed state. Results of the present study suggest that CsA acts directly on the HERG channel as an open-channel blocker, and it acts independently of its effect on calcineurin activity.

• Journal of Korean Academy of Nursing
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• 제50권2호
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• pp.286-297
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• 2020

Purpose: This study aimed to identify the effects of myofascial pain syndrome on shoulder pain, range of motion, and body composition around the shoulder in middle-aged women. Methods: A total of 72 women participated in the randomized controlled trial. The subjects were grouped into an experimental group (n=39) and a control group (n=33). The experimental group received a resistance exercise program using an elastic band for 8 weeks, 3 days a week. The control group followed a normal daily for 8 weeks. Measurements were conducted three times; before the experimental treatment (pre-test), the 2nd and 8th weeks after treatment. Results: Regarding the general characteristics and homogeneity of the dependent variables, there were no significant differences between the two groups, except for the thickness of the left and right muscles and the left fat. After treatment, shoulder pain was significantly different between the two groups (F=18.54, p<.001) and the range of shoulder motion was significantly different (left, F=86.70, p<.001; right, F=98.66, p<.001). Furthermore, there were a significant differences in the thickness of muscles between the two groups (left, F=40.20, p<.001; right, F=29.57, p<.001); however, the thickness of fat was not significantly different. Conclusion: The resistance exercise program reduces shoulder pain and improves the range of motion of the shoulder joint and increases muscle mass on around the shoulder. It suggests to conduct a study to confirm the long-term exercise effect.

• Journal of Environmental Impact Assessment
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• 제18권3호
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• pp.161-170
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• 2009

As urban growth continues, the earth ecosystem is increasingly dependent on the patterns of urban growth. The impact intensity from urban growth is expected to change predictably with distance from the urban center. However we can't fully understand yet how urban development pattern affects urban ecosystem. In researches about urban ecosystem, it is important to relate the spatial pattern of urbanization to ecological processes. So we used gradient analysis with time data; 1980's, 1990's and 2000's. We attempted to quantify the urban spatiotemporal impacts in Daejeon-city and Cheonan-city, Korea, along a 75km long and 3km wide transect. Through the results, we found the impacts range of urbanization with urban development process of two cities. When the urban growth was concentrated on in both cities, the impacts intensity and range were much stronger and wider. As a result, in urban planning or green space planning, we have to consider suitable urban development forms with surrounding areas, and make legal clauses which limits landuse change. This quantifying the urban gradient is an important step in understanding urban ecology.

• Toxicological Research
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• 제31권1호
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• pp.77-88
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• 2015

Lithospermum erythrorhizon has long been used in traditional Asian medicine for the treatment of diseases, including skin cancer. The oral toxicity of a hexane extract of Lithospermum erythrorhizon root (LEH) was investigated in Beagle dogs by using single escalating doses, two-week dose range-finding, and 4-week oral repeat dosing. In the single dose-escalating oral toxicity study, no animal died, showed adverse clinical signs, or changes in body weight gain at LEH doses of up to 2,000 mg/kg. In a 2 week dose range-finding study, no treatment-related adverse effects were detected by urinalysis, hematology, blood biochemistry, organ weights, or gross and histopathological examinations at doses of up to 500 mg LEH/kg/day. In the 4 week repeat-dose toxicity study, a weight loss or decreased weight gain was observed at 300 mg/kg/day. Although levels of serum triglyceride and total bilirubin were increased in a dose dependent manner, there were no related morphological changes. Based on these findings, the sub-acute no observable adverse effect level for 4-week oral administration of LEH in Beagles was 100 mg/kg/day.

• Biomolecules & Therapeutics
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• 제18권3호
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• pp.235-245
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• 2010

Mitochondria have long been recognized as ATP engines for the cell and recently as a dynamic and mobile organelles that control cell death and life. This exquisite organelle is the site of reactive oxygen species production and is highly vulnerable to exogenous stresses, resulting in catastrophic damage to the cell. Mitochondrial dysfunction is linked to a wide range of age-associated degenerative diseases, such as metabolic syndrome, cardiovascular disease, and neurodegenerative diseases. Understanding the molecular mechanisms of mitochondria-dependent pathogenesis may provide important strategies to treat these diseases. Indeed, mitochondria are emerging therapeutic targets for the mitochondria-related diseases. In this paper, we review the recent concepts of mitochondrial biology and how mitochondria are involved in age-associated degenerative diseases. Furthermore, we summarize the therapeutics which target to improve mitochondrial functions.