• International Journal of Highway Engineering
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• v.6 no.4 s.22
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• pp.75-89
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• 2004

Long term performance of concrete pavement significantly depends on the given construction and environmental condition. It means that random cracks and extreme crack width due to inappropriate quality control at the early age might lead to decreasing the pavement service life. The temperature and moisture during the construction, cement and aggregate types, curing condition are major components to affect the quality of the concrete pavement at the early age. First of all, the high temperature differential, that is made by increasing air temperature and the heat of cement hydration, is known as the major contributor to severe cracks. In this study, tent covering was used for controlling temperature of the concrete slab. The field measurement data indicates that the effect of the tent covering is very significant to decrease possibilities of random crack occurrence and curling stress and enhance the long-term concrete strength. HIPERPAV(High PERformance PAVing software), a program predicting the strength and stress of an earty-age concrete pavement (72 hour after placement), is used for simulating the effects of tent covering. The HIPERPAVE results showed that the section with the tent covering has higher reliability than the section without the tent covering by 22.5%. In details, reliability is increased 72.5% (without the tent covering) to 95% (with the tent covering).

• Journal of the Korea Convergence Society
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• v.9 no.7
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• pp.87-93
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• 2018

In this study, $^{99m}Tc$, $^{123}I$, $^{201}Tl$, $^{18}F$, and $^{131}I$, which are widely used in nuclear medicine, were transmitted through a bismuth shield. We investigated the shielding rates according to the type of radioisotope and the distance of measurement. For the experiment, 6 sheets of lead equivalent 0.25 mm Pb of bismuth shielding material were stacked one by one up to 1.50 mm as the thickness increased. The distance was 30 cm, 50 cm, and 100 cm, and the transmission dose was measured. As a result, the shielding rates was measured as the thickness increased, and the measured value decreased as the distance increased. The shielding rate of $^{123}I$ and $^{201}Tl$ was higher than $^{99m}Tc$, $^{18}F$ and $^{131}I$ showed lower shielding effect when there is a shielding material than when there is no shielding material due to high energy and ${\beta}$ rays. Based on the results of experiments, it would be helpful to reduce the exposure of nuclear medicine workers and to manage the exposure if bismuth shields are used depending on the type of radioisotope.

• Journal of Oral Medicine and Pain
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• v.33 no.1
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• pp.1-8
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• 2008

It is well known that many antimicrobial proteins in saliva interact with each other. The purpose of the present study was to investigate the interactions of lysozyme with peroxidase in the aspects of enzymatic activity in vitro. The interactions of lysozyme with peroxidase were examined by incubating hen egg-white lysozyme(HEWL) with bovine lactoperoxidase(bLP). The influence of peroxidase system on lysozyme was examined by subsequent addition of potassium thiocyanate and hydrogen peroxide. Lysozyme activity was determined by turbidity measurement of a Micrococcus lysodeikticus substrate suspension. Peroxidase activity was determined with an NbsSCN assay. The Wilcoxon signed rank test was used to analyze the changes of enzymatic activities compared with their controls. bLP at physiological concentrations enhanced the enzymatic activity of HEWL(P < 0.05) and its effect was dependent on the concentration of peroxidase. However, HEWL did not affect the enzymatic activity of bLP. Thiocyanate did not affect the enzymatic activity of HEWL, either. The addition of potassium thiocyanate and hydrogen peroxide did not lead to additional enhancement of the enzymatic activity of HEWL. The changes of hydrogen peroxide concentration in the peroxidase system did not affect the enzymatic activity of HEWL. Collectively, despite an in vitro nature of our study, the results of the present study provide valuable information on the interactions of lysozyme and peroxidase in the aspects of enzymatic activity in oral health care products and possibly in the oral cavity.

• Communications of Mathematical Education
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• v.27 no.4
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• pp.449-472
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• 2013

Instructional materials including problem situations or problems or tasks on real-life situations are considered as an important and significant factor to lead a successful math instruction. MiC Textbook is a representative one showing good examples and tasks including fluent realistic situations on the basis of the background of the Freudenthal's theory. This study explores concretely and in detail the type of level of mathematical tasks, by the subject of MiC Textbook. To accomplish this, this study reconstructs and establishes an elaborated analysis framework using 'the cognitive demand level' suggested by Stein, et, al. The cognitive demand level is comprized of four elements such as Memorization Tasks, Procedures Without Connections Tasks, Procedures With Connections Tasks, and Doing Mathematics Tasks. Memorization Tasks and Procedures Without Connections Tasks are considered as low level tasks, and Procedures With Connections Tasks and Doing Mathematics Tasks are as high level tasks. MiC Textbook is comprized of the four areas of 'number', 'algebra', 'geometry and measurement', and 'data analysis and statistics'. This study deals with the tasks relevant to Function content dealt with in MiC 3 level Textbook, and explore the level of cognitive demands on each task.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.4
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• pp.335-344
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• 2006

The domestic standards which used the standards of Road Association of Japan standards presents the distances of between jet-fans by the caliber of jet-fan. However, the Permanent International Association of Road Congress (PIARC) encourages it to be ten times a diameter of the tunnel. The distance of jet-fans installed in bases of two standards differs as much as two times, as so the proper basis after analysis of internal air current is needed since such difference can lead to disadvantage for selection of ventilation configuration. Based on Froude modeling theory, 1/40 scale acrylic model of a tunnel (215mm in diameter and 6.9m in length) and jet-fan (26.3mm and 31.6mm in caliber) was made for the measurement of changes in pressure and velocity due to the extension of tunnel for analysis of internal air current. And we measured the changes in pressure of surroundings of a jet-fan for confirmation of recirculation due to the exterior airs when the jet-fan is on. The results of the model test show that internal air current was not influenced by the caliber of jet-fan and its changes in pressure and velocity were stable in the point where it was nine times of diameter of the tunnel. Also the recirculation when the jet-fan is on could be verified. According to such results, in the cases of installing jet-fan in tunnels, the distances between jet-fans needs to be more than nine times the diameter.

• Korean Journal of Pharmacognosy
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• v.47 no.2
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• pp.122-127
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• 2016

Methicillin-Resistant Staphylococcus aureus(MRSA) is a multidrug-resistant(MDR) strain. (+)-Usnic acid(UA) is uniquely found in lichens, and is especially abundant in genera such as Usnea and Cladonia. UA has antimicrobial activity against human and plant pathogens. Therefore, UA may be a good antibacterial drug candidate for clinical development. In search of a natural products capable of inhibiting this multidrug-resistant bacteria, we have investigated the antimicrobial activity of UA against 17 different strains of the bacterium. In this study, the effects of a combination of UA and permeable agents against MRSA were investigated. For the measurement of cell wall permeability, UA with concentration of Ethylenediaminetetraacetic acid(EDTA) was used. In the other hand, Sodium azide($NaN_3$) was used as inhibitors of ATPase. Against the 17 strains, the minimum inhibitory concentrations(MICs) of UA were in the range of $7.81-31.25{\mu}g/ml$. EDTA or $NaN_3$ cooperation against MRSA showed synergistic activity on cell wall. UA and in combination with EDTA and $NaN_3$ could lead to the development of new combination antibiotics against MRSA infection.

• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.517-522
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• 2020

Electron beam have many factors that affect dose distribution, so even if identical settings are used, they should be identified and used for radiation treatment, and the effects on the structures in the body are sensitive, making it difficult to investigate uniform dose distribution on tumors. In this study, a dosimeter was produced using PbI₂ which is a photoelectric material, and electrical characteristics were analyzed for 6, 9, and 12 MeV electronics in linear accelerators. The reproducibility test results showed that RSD were 1.1215%, 1.0160%, and 0.05137% respectively at 6, 9, and 12 MeV energies, indicating that the output signals were stable. The linearity evaluation results showed that the R² values of the reliability indicator for straight line trend lines were 0.9999, 0.9999, and 0.9994, respectively, at 6, 9, and 12 MeV, to confirm that the output signal was proportional to PbI₂ as dose increased. The PbI₂ dosimeter in this study is judged to be highly applicable to electromagnet measurement and is thought to be able to be used as a basic study of electron detector through photoelectric material.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.194-201
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• 2012

Moxibustion is utilized not only to cure disease but also to increase immunity. However, it may lead to undesired effects including severe pains(blisters and burns) because of the difficulty of controlling heat intensity. To overcome these problems we developed the RF heat stimulation system which can control stimulus. Also, we developed the RF stimulation protocol for effective heat transfer in subcutaneous tissue of rabbit. RF stimulator consists of a medical RF capacitive heating device, isolation probe, isolation plate, negative pressure control part and temperature measurement part. For the designed stimulus protocol, we measured the temperature distribution on epidermis and in subcutaneous(5mm, 10mm) area of rabbit during moxibustion. A stimulation protocol was designed by controlling the ON/OFF duty ratio, repeating number, and energy of applied pulse to get the temperature distribution similar with that by moxibustion. In results, the correlation coefficients between temperature distribution by moxibustion and that of stimulator were 95% and 91% from 5mm and 10mm thick respectively. However, temperature distribution on epidermis by stimulator was remarkably lower than that of the moxibustion. Finally, the RF stimulation system showed that it can not only transfer effectively heat similar with moxibustion to the subcutaneous area, but also the influence by unwanted side effects can be minimized.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.864-867
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• 2003

GPS (Global Positioning System) made by the Department of Defense in U.S.A is positioning system to use satellite and initially it has been used only for the military forces but open to civilian in about 1987. This system has widely been used for not only surveying land, but also car navigation on the street and means to build up the data of the GIS. With GPS, recently our country is accelerating to make imbeded system and also the study on imbeded system is well under way. For example, Car navigation and the construction of the Seokang bridge between Willson Arch at Han river by using DGPS were evaluated as successful model to lead accurate location with the precision of the cm. The examples of the project performance with GPS has gradually been extended to the each department organization of the local and central government. for the example, It is true that BIS(Bus Information System) is widely spreading out. In addition, the study on the Distribution Maintenance System is expected to be well in progress to take advantage of GPS based on the data base of the NGIS(National Geography Institute System) of the NGI(National Geography Institute). This paper shows that we embodied not only the large imbeded system for car and finding the location in Korean Land Corporation but also the protype of the kinematics Wrist Held which is easily portable to pedestrian, climber and marathon runner.

• Progress in Medical Physics
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• v.12 no.1
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• pp.71-77
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• 2001

The region, near the edge of a radiation beam, where the dose changes rapidly according to the distance from the beam axis is known as the penumbra. There is a sharp dose gradient zone even in megavoltage photon beams due to source size, collimator, lead alloy block, other accessories, and internal scatter ray. We investigate dosimetric characteristics on penumbra regions of a standard collimator and compare to those of theoritical model for the optimal use of the system in radiotherapy. Peripheral dose distribution of 6 W Photon beams represents penumbral forming function as the depth. Also we have discussed that the peripheral dose distribution of clinical photon beams, differences between calculation dose use of emperical penumbral forming function and measurements in penumbral region. Predictions by emperical penumbral forming functions are compared with measurements in 3-dimensional water phantom and it is shown that the method is capable of reproduceing the measured peripheral dose values usually to within the statistical uncertainties of the data. The semiconductor detector and ion chamber were positioned at a dmax depth, 5cm depth, 10cm depth, and its specific ratio was determined using a scanning data. The effective penumbra, the distance from 80% to 20% isodose lines were analyzed as a function of the distance. The extent of penumbra will also expand with depth increase. Difference of measurement value and model functions value according to character of the detector show small error in dose distribution of the peripheral dose.