• Journal of Life Science
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• v.18 no.12
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• pp.1644-1650
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• 2008

The essential oil of tea tree (Melaleuca alternifolia) is widely used in traditional Australian medicine for skin lesions and infected injuries. In the present study, we investigated the chemical composition, cytotoxicity and its biological activities. The composition of the oil was analyzed by GC-MS. ${\beta}$-Terpinene (20.87%), ${\alpha}$-pinene (17.60%), p-cymene (11.23%), 3-carene (10.40%), trans-anethole (8.47%) and limonene (4.65%) were the major components in the oil. The results tested by MTT assay indicated that the oil showed no cytotoxic effect, at concentrations up to 5%, for less than 3h. The antiradical capacity was evaluated by measuring the scavenging activity of the essential oil on the 2,20-diphenylpicrylhydrazyl (DPPH) and 2,2'-azino-bis 3-ethyl benzothiazoline-6-sulfonic acid (ABTS) radicals. The oil was able to reduce the both radicals dose-dependently, and the concentration required for 50% reduction ($RC_{50}$) against ABTS radicals ($1.6{\pm}0.02%$) was slightly lower than DPPH radicals ($2.6{\pm}0.29%$). The direct contact and vapor-phase antibacterial activity of the oil were also evaluated using disc diffusion method against Staphylococcus aureus, Streptococcus mutans, Listeria monocytogenes, Acinetobacter baumannii, Escherichia coli, and Vibrio parahaemolyticus. All the Gram-negative bacterial strains tested showed more sensibility to the oil than the Gram-positive strains when compare to the effect of gentamycin. On the other hand, the vapor phase of the essential oil against S. aureus exhibited strongest inhibitory effect.

• Proceedings of the Korean Geotechical Society Conference
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• 1995.10a
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• pp.15.2-22
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• 1995

Evaluating stiffness of near-surface materials has been one of the critically important tasks in many civil engineering works. It is the main goal of geotechnical characterization. The so-called deflection-response method evaluates the stiffness by measuring stress-strain behavior of the materials caused by static or dynamic load. This method, however, evaluates the overall stiffness and the stiffness variation with depth cannot be obtained. Furthermore, evaluation of a large-area geotechnical site by this method can be time-consuming, expensive, and damaging to many surface points of the site. Wave-propagation method, on the other hand, measures seismic velocities at different depths and stiffness profile (stiffness change with depth) can be obtained from the measured velocity data. The stiffness profile is often expressed by shear-wave (S-wave) velocity change with depth because S-wave velocity is proportional to the shear modulus. that is a direct indicator of stiffiiess. The crosshole and downhole method measures the seismic velocity by placing sources and receivers (geophones) at different depths in a borehole. Requirement of borehole installation makes this method also time-consuming, expensive, and damaging to the sites. Spectral-Analysis-of-Surface-Waves (SASW) method places both source and receivers at the surface, and records horizontally-propagating surface waves. Based upon the theory of surfacewave dispersion, the seismic velocities at different depths are calculated by analyzing the recorded surface-wave data. This method can be nondestructive to the sites. However, because only two receivers are used, the method requires multiple measurements with different field setups and, therefore, the method often becomes time-consuming and labor-intensive. Furthermore. the inclusion of noise wavefields cannot be handled properly, and this may cause the results by this method inaccurate. When multi-channel recording method is employed during the measurement of surface-waves, there are several benefits. First, usually single measurement is enough because multiple number (twelve or more) of receivers are used. Second, noise inclusion can be detected by coherency checking on the multi-channel data and handled properly so that it does not decrease the accuracy of the result. Third, various kinds of multi-channel processing techniques can be applied to f1lter unwanted noise wavefields and also to analyze the surface-wavefields more accurately and efficiently. In this way, the accuracy of the result by the method can be significantly improved. Fourth, the entire system of source, receivers, and recording-processing device can be tied into one unit, and the unit can be pulled by a small vehicle, making the survey speed very fast. In all these senses, multi-channel recording of surface waves is best suited for a routine method for geotechnical characterization in most of civil engineering works.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.6 no.2
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• pp.331-346
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• 1999

Many studies have reported that a lot of nursing colleges do not have good facilities for the nursing practice in hospitals, so many students do not have the good ability which is needed to be a competent nurse. The purpose of this study was to develop a program in which students could improve their ability in fundamental nursing skills before the graduation. This study was primarily designed to identify items of the fundamental nursing practice in which nursing college students have perceived deficiencies. According to previous studies, a total 75 items were presented. In Identifying them, a modified Porter format was used. The questionnaire contained three sections. A. How well do you think you can/could perform the item when you graduate/graduated the college? B. How well do you think you should perform/should be able to perform the item when you graduate/graduated the college? C. How important do you think the item is? For each of the 75 items, the respondents were instructed to answer the above three questions, by circling a number on a rating scale extending from 1 to 5, where low numbers represented a low degree of performance or minimum amount, and high numbers represented a high degree of performance or maximum amount. The perceived degree of deficiency in performance on each questionnaire item was obtained by subtracting the answer to Part A of an item from that to of Part B. The larger difference means a larger perceived degree of deficiency in performance. This method of measuring the perceived degree of deficiency in performance is an indirect measure derived from two direct answers by the respondent for each item. From this result Part C of each item was used to rank the items, and the items were prioritized. The items which had the highest priority were IV injection, simple catheterization, indwelling catheterization, CPR, and nurse recording. By this method, through these results from a nursing college, and the items which will be used first in developing the supplementation program for nursing college students can be identified.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.3 s.168
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• pp.115-122
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• 2005

As the digital TV markets rapidly growing, many manufacturers introduce large size flat screen TV units. There are two different display types available to large size models which are plasma and TFT-LCD. Since both are constructed with thin large panels that are mostly fragile to even moderate mechanical shock inputs. Some large size panels are severely resonated by the acoustic sound generated TV which deteriorates video quality. Recognizing the potential problems of large displays, accurate measurement of the panels is to be an essential task for the reliable design. Measurement of mechanical properties of a thin large crystallized panel such as TFT-LCD display with traditional material testing equipments is challenging. Since TFT-LCDs are constructed with combination of brittle glass panels, polymer sheets, and liquid crystal, their properties are not only anisotropic but also usually non-linear. Accurate measurement of the properties often requires very expensive facilities. Especially when the size of the test sample is as large as 40-inch or wider, direct measurement cost is prohibitive. Even worse, machining of the large TFT-LCD to make a smaller size specimen that could be fit into a material tester is not possible because of liquid crystal leakage. A new method fer the measurement of elastic modulus of large TFT-LCD panel is presented in this article. The suggested method provides a simple, economic, and user-friendly way fer measuring the elastic modulus of large panels with considerable level of accuracy.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.938-946
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• 2008

This study is on sealing leakage holes where are in landfills to make clay cakes with clay particles, which have a negative surface charge using the method of electrophoresis. Generally, electrophoresis is the motion of charged particles in a colloid under the influence of an electric field; particles with a positive charge go to the cathode and negative to the anode. In this study in order to develop the prevention system of leakages of the leachate in landfills, one-dimensional electrophoresis tests were conducted for determining the properties of the motion of the electrophoresis and cutoff using the method of electrophoresis depending on various the effect factors such as types of clays, concentrations of the clays, and applied electric field. In case of the experiments of determining the optimum clays, Na and Ca-Bentonite, Na and Ca-Montmorillonite, which have greater zeta-potential, cation, exchange capacity as well as ability of cutoff, and Micro-cement inducing cementation were chosen and then the effect of those clays was investigated. Moreover, the properties of the motion and settling of the clays were investigated following electric field varied from 0 to 1V/cm at different concentration of the clays in order to determine both the properties of the motion of the clays and the efficiency of electric field when applying different direct current. Ultimately, the ability of cutoff was examined through measuring the permeability of the clay cakes derived from the one-dimensional electrophoresis tests.

• Food Science of Animal Resources
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• v.40 no.3
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• pp.350-361
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• 2020

Quality control of meat products is one of the main concerns of consumers, governmental control authorities, and retailers. The purpose of this study was to employ ribose-induced Maillard reaction in detection of meat adulteration and differentiation of fresh-chilled from frozen-thawed minced veal. The browning intensity was assessed through measuring the absorbance at 420 nm with a spectrophotometer as well as the direct analysis of the color and pH. The results showed that CIE b*, CIE a*, and A_420* values in the extract of fresh-chilled veal were significantly (p<0.05) higher than frozen-thawed samples. The extract of frozen meat samples stored at -18℃ became significantly darker and more yellowish compared to -4℃. The results showed that the A_420* value in the frozen-thawed veal stored at -4℃ and -18℃ was reduced by approximately 17.22±3.53% and 11.68±2.49%, respectively, compared with fresh-chilled veal. The findings also showed that the storage temperature of minced veal and the heating time in this reaction had a significant effect on all tested variables (p<0.0001). The proposed method can be considered as an easy, quick, and inexpensive test for differentiating between the fresh-chilled and frozen-thawed minced veal.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2173-2178
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• 2008

Railroad is the major factor of vibration source in railway vehicles, and it must carefully maintained the original condition to secure the safety and good ride comfort of passenger. Measuring the condition of rail irregularities such as surface, alignment, gauge, twist and cant etc is required to maintain the good performance of railroad. Currently, the various rail irregularity measurement systems(EM120, ROGER1000K and the Total Rail Irregularity Measurement system of Korea High Speed Train) are operated in Korea to estimate the rail irregularity. It is hard to verify the correlation of one rail irregularity data of a measurement system with the other, because they have been adopted different rail irregularity estimation methods. The best method securing the reliability of the irregularity data is the direct confirmation on the ground where the measurement system had detected as a fault section, but it is impossible to apply all sections simultaneously due to limitation of time, labor, cost and equipments. There is a method to secure the reliability of the data by using acceleration values. Rail irregularities, the major factor of vibration in railway vehicle, are transmitted to the vehicle acceleration through masses, springs, dampers and joints as the system dynamic formation. In this study, Transition Function has been adopted by using the rail irregularity and the acceleration value regarding as input & output parameters respectively. It has been verified by comparing the analyzed results with real measured irregularity data from the Total Rail Irregularity Measurement system of Korea High Speed Train. Also various methods has been accomplished to verify the correlation between rail irregularities and acceleration values.

• Journal of radiological science and technology
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• v.45 no.1
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• pp.57-67
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• 2022

CZT detectors, which are compound semiconductors that have been widely used recently for gamma-ray detection purposes, are difficult to detect neutrons because direct interaction with them does not occur unlike gamma-rays. In this paper, a method of detecting and determining energy levels (fast neutrons and thermal neutrons) of neutrons, in addition of identifying energy and nuclide of gamma-rays, and evaluating gamma dose rates using a CZT semiconductor detector is described. Neutrons may be detected by a secondary photoelectric effect or compton scattering process with a characteristic gamma-ray of 558.6 keV generated by a capture reaction (¹¹³Cd + ¹n → ¹¹⁴Cd + 𝛾) with cadmium (Cd) in the CZT detector. However, in the case of fast neutrons, the probability of capture reaction with cadmium (Cd) is very low, so it must be moderated to thermal neutrons using a moderator and the material and thickness of moderator should be determined in consideration of the portability and detection efficiency of the equipment. Conversely, in the case of thermal neutrons, the detection efficiency decreases due to shielding effect of moderator itself, so additional CZT detector that do not contain moderator must be configured. The CZT detector that does not contain moderator can be used to evaluate energy, nuclide, and gamma dose-rate for gamma-rays. The technology proposed in this paper provides a method for detecting both neutrons and gamma-rays using a CZT detector.

• Imaging Science in Dentistry
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• v.35 no.1
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• pp.15-23
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• 2005

Purpose : To compare cephalometric measurement between measuring methods in digital and conventional lateral cephalometric radiograph. Materials and Methods : Twenty digital and conventional lateral cephalometric radiographs were selected. In digital group, cephalometric measurements were performed manually using hardcopies and automatically using $V-Ceph^{TM}$ program on the monitor. In conventional group, the same measurements were performed manually on conventional films, and for automatic measurement conventional films were digitized by scanner. All measurements were performed twice by 4 observers, and 24 cephalometric variables were calculated and the time spent for each measurement was recorded. The differences in measurements data and the time spent for each measurement were compared within each group. Intra-observer and inter-observer comparisons were performed. Results : In both groups, no statistically significant difference between manual and automatic measurements was observed and most of the variables didn't show statistically significant differences between methods. The observer with less experience tended to show statistically significant differences of measurements between methods, and differences from other observers. The differences of measurements between methods in digital group were lesser than those of conventional group with statistical significance in 8 variables out of 24. With automatic method and in digital group, the spent time was shorter. Conclusion : With direct digital radiograph, automatic method using manually idenitified landmarks can be preferable in cephalometric analysis. (Korean J Oral Maxillofac Radiol 2005; 35 : 15-23)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.475-480
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• 2017

In this paper, the conductivity of the fine pattern is improved in the insulating substrate by laser-induced forward transfer (LIFT) process. The high laser beam energy generated in conventional laser induced deposition processes induces problems such as low deposition density and oxidation of micro-patterns. These problems were improved by using a polymer coating layer for improved deposition accuracy and conductivity. Chromium and copper were used to deposit micro-patterns on silicon wafers. A multi-pulse laser beam was irradiated on a metal thin film to form a seed layer on an insulating substrate(SiO2) and electroless plating was applied on the seed layer to form a micro-pattern and structure. Irradiating the laser beam with multiple scanning method revealed that the energy of the laser beam improved the deposition density and the surface quality of the deposition layer and that the electric conductivity can be used as the microelectrode pattern. Measuring the resistivity after depositing the microelectrode by using the laser direct drawing method and electroless plating indicated that the resistivity of the microelectrode pattern was $6.4{\Omega}$, the resistance after plating was $2.6{\Omega}$, and the surface texture of the microelectrode pattern was uniformly deposited. Because the surface texture was uniform and densely deposited, the electrical conductivity was improved about three fold.