• Korean Journal of Human Ecology
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• v.17 no.5
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• pp.1027-1035
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• 2008

Essentail oils and carrier oils are generally used for Aromatherapy. Therefore the toxicity, possibilities of irritations and sensitive reactions and injury of essential oils must be considered for clients and therapists. So that, in this studies a toxicity of jojoba and 4 species essential oils (fennel, mandarine, tea tree and cedarwood) were investigated by the measurement of MTT-assay and sirius red staining. Liver, kidney and brain tell were chosen for the cell viability assay and observation of morphological change. In the result, no cytotoxicity was observed on live., kidney and brain cell at concentration of 0.01 $\mu\el/m\el$ jojoba oil. And lysis and nucleus breaking were not observed at same concentration of jojoba oil on live., kidney and brain cell. fennel oil was showed 50% of cell viability and inhibited cell growth on liver, kidney and brain cell at relatively high concentration compared with the other oils. 50% of liver, kidney and brain cell viability and delayed cell growth of tea tree and mandarine oil were revealed at lower concentration than fennel oil. In cedarwood oil, 50% of liver cell viability at concentration of 0.00067 $\mu\el/m\el$ was showed, but cell viability and cell growth of kidney and beam cell were effected at the lowest concentration compared with other oils. So that, jojoba oil as using of carrier oil may be not harmful. And 3 essential oils from the fennel, tea tree and mamdarine may have very low toxicity, but cedarwood may be used carefully for inhalation. And over dosage of concentrated cedarwood oil should be not directly touched and exposured, and absolute essential oils must be diluted with carrier oils for topical and systematic massage.

• Korean Journal of Food Science and Technology
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• v.30 no.3
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• pp.509-516
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• 1998

Thermoluminescence measurements were applied to the detection of seasoned-powered foods such as shellfish extract powder, seasoned marine products, Ramen soup powder and sardine extract powder whether they are irradiated or not. Correlation coefficients $(R^2)$ between irradiation doses and corresponding TL responses were more than 0.5966 in all samples and 0.9500 in Ramen soup powder. TL threshold value was pre-established for the detection of unknown Ramen soup powders by verifying TL responses with a re-irradiation step. Threshold values were maximum 1.37 for the nonirradiated samples and minimum 6.06 for the 2.5 kGy-irradiated samples. The samples showing values between 1.37 and 6.06 were subjected to a re-irradiation step for their detection, which results were reconfirmed by enumerating the total bacterial load of the detected samples. Pre-established threshold values were successfully applicable to the detection of 167 coded unknown samples, both nonirradiated and irradiated with gamma or electron-beam energy. In the assessment of irradiated doses, three calibration curves were pre-established by plotting TL intensity versus applied doses, of which a quadratic equation was obtained for the potential estimation of irradiated doses with some variations from the real doses.

• International Journal of Oral Biology
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• v.42 no.4
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• pp.155-161
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• 2017

Teeth and bones are highly mineralized tissues containing inorganic minerals such as calcium phosphate, and a growing number of evidences show that their mineral content is associated with many diseases. Although the quantification of mineral contents by micro-computed tomography(micro- CT) has been used in diagnosis and evaluation for treating bone diseases, its application for teeth diseases has not been well established. In this study, we attempted to estimate a usefulness of a high-resolution micro-CT in analysis of human teeth. The teeth were scanned by using the Skyscan 1172 micro-CT. In order to measure tooth mineral content, beam hardening effect of the machine was corrected with a radiopaque iodine-containing substance, iodoacetamide. Under the maximum resolution of $6.6{\mu}m$, X-ray densities in teeth and hydroxyapatite standards were obtained with Hounsfield unit (HU), and they were then converted to an absolute mineral concentration by a CT Analyzer software. In enamel layer of cusp area, the mean mineral concentration was about $2.14mg/mm^3$ and there was a constant mineral concentration gradient from the enamel surface to the dentinoenamel junction. In the dentin of middle 1/3 of tooth, the mean mineral concentration was approximately $1.27mg/mm^3$ and there was a constant mineral concentration gradient from the outer of root to the pulp side, ranging from 1.3 to $1.06mg/mm^3$. In decay region of dentin, the mineral content was gradually decreased from the intact inner side to the decayed surface. These results suggest that high-resolution micro-CT can be as a useful tool for non-invasive measurement of mineral concentration in teeth.

• Journal of the Korean Ceramic Society
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• v.38 no.11
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• pp.973-979
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• 2001

Tin-doped indium oxide (ITO) thin films were deposited using r.f. magnetron reactive sputtering and the electrical properties, such as the resistivity, carrier concentration and mobility, were investigated as a function of the sample position under a given magnetron sputtering condition. The nonhomogeneity of the electrical properties with the sample position was observed under a given magnetron sputtering condition. The resistivity of ITO thin film on the substrate which corresponded to the center of the target had a minimum value, 2∼4$\times$10$\^$-4/$\Omega$$.$cm, and it increased symmetrically when the substrate deviated from the center. The density measurement result also showed that ITO thin film deposited at the center has a maximum density of 7.0g/cm$^3$, which was a relative density of about 97%, and the density decreased symmetrically as the substrate deviated from the center. The nonhomogeneity of electrical properties with the deposition position could be explained with the incidence angle of the source beam alpha, which is related with an atomic self-shadowing effect. It was confirmed experimentally that the density in film affect both the carrier mobility and the conductivity. In the case where the density of ITO thin film is 7.0g/cm$^3$, the magnitude of the mean free path was identical with that of the grain size(the diameter of column). However, in the other cases, the mean free path was smaller than the grain size. These results showed that the scattering of the free electrons at the grain boundary is the major factor for the electrical conduction in ITO thin films having a high density, and there exists other scattering sources such as vacancies, holes, or pores in ITO thin films having a low density.ing a low density.

• Steel and Composite Structures
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• v.13 no.3
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• pp.239-258
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• 2012

In this paper, experimental investigations on high strength steel (HSS) stud connected steel-concrete composite (SCC) girders to understand the effect of shear connector density on their flexural behaviour is presented. SCC girder specimens were designed for three different shear capacities (100%, 85%, and 70%), by varying the number of stud connectors in the shear span. Three SCC girder specimens were tested under monotonic/quasi-static loading, while three similar girder specimens were subjected to non-reversal cyclic loading under simply supported end conditions. Details of casting the specimens, experimental set-up, and method of testing, instrumentation for the measurement of deflection, interface-slip and strain are discussed. It is found that SCC girder specimen designed for full shear capacity exhibits interface slip for loads beyond 25% of the ultimate load capacity. Specimens with lesser degree of shear connection show lower values of load at initiation of slip. Very good ductility is exhibited by all the HSS stud connected SCC girder specimens. It is observed that the ultimate moment of resistance as well as ductility gets reduced for HSS stud connected SCC girder with reduction in stud shear connector density. Efficiency factor indicating the effectiveness of high strength stud connectors in resisting interface forces is estimated to be 0.8 from the analysis. Failure mode is primarily flexure with fracturing of stud connectors and characterised by flexural cracking and crushing of concrete at top in the pure bending region. Local buckling in the top flange of steel beam was also observed at the loads near to failure, which is influenced by spacing of studs and top flange thickness of rolled steel section. One of the recommendations is that the ultimate load capacity can be limited to 1.5 times the plastic moment capacity of the section such that the post peak load reduction is kept within limits. Load-deflection behaviour for monotonic tests compared well with the envelope of load-deflection curves for cyclic tests. It is concluded from the experimental investigations that use of HSS studs will reduce their numbers for given loading, which is advantageous in case of long spans. Buckling of top flange of rolled section is observed at failure stage. Provision of lips in the top flange is suggested to avoid this buckling. This is possible in case of longer spans, where normally built-up sections are used.

• Progress in Medical Physics
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• v.15 no.4
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• pp.237-246
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• 2004

Even though the wedge factor was defined by ICRU, RTPS uses other definition different from the wedge factor to consider the wedge effect to correct dose. Because the factors with different concept are defined in a very different way, replacement of different factor could make severe error of dose and is unacceptable because their values are very different from each other. Radiotherapy machine installed in department includes physical wedges and function of dynamic wedge by upper jaws, and Eclipse and Pinnacle$^{3}$ such as RTPS are used. The wedge factors, relative wedge output factors and wedge field output factors of physical wedges and dynamic wedges were measured by an ionization chamber in water phantom. They are analyzed and compared in according to wedge position, field size, wedge angle, X-ray quality, measurement condition. Wedge factor, relative wedge output factors and wedge field output factors of dynamic wedges comparing physical wedges have an effect of several factors. Main factors effecting to the factors of dynamic wedges were field size and wedge angle. Beam quality of X-ray introduces a few effect to the factors. Because the factors related to wedge and defined with different concepts are different from each other, to reduce dose error it should be input by values proper to RTPS.

• Journal of IKEEE
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• v.21 no.4
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• pp.368-374
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• 2017

In this Paper, we developed a low power type LED security light using LED lighting that substitutes a 220[V] commercial power source for a solar cell module instead of a halogen or a sodium lamp. in addition, a PWM type drive control circuit is designed to minimize the heat generation problem and the drive current of the LED drive controller. in developed system, The light efficiency measurement value is 93.6[lm/W], and a high precision temperature sensor is used inside the controller to control the heat generation of the LED lamp. In order to eliminate the high heat generated from the LED lamp, it is designed to disperse quickly into the atmosphere through the metal insertion type heat sink. The heat control range of LED lighting was $50-55[^{\circ}C]$. The luminous flux and the lighting speed of the LED security lamp were 0.5[s], and the beam diffusion angle of the LED lamp was about $110[^{\circ}C]$ by the light distribution curve based on the height of 6[m].

• Korean Journal of Optics and Photonics
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• v.4 no.1
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• pp.15-21
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• 1993

This paper describes the design and development of a KrF excimer laser stepper and discusses the detailed system parameters and characterization data obtained from the performance test. We have developed a deep UV step-and-repeat system, operating at 248 nm, by retrofitting a commercial modules such as KrF excimer laser, precision wafer stage and fused silica illumination and 5X projection optics of numerical aperture 0.42. What we have developed, to the basic structure, are wafer alignment optics, reticle alignment system, autofocusing/leveling mechanisms and environment chamber. Finally, all these subsystem were integrated under the control of microprocessor-based controllers and computer. The wafer alignment system comprises the OFF-AXIS and the TTL alignment. The OFF-AXIS alignment system was realized with two kinds of optics. One is the magnification system with the image processing technique and the other is He-Ne laser diffraction type system using the alignment grating on the wafer. 'The TTL alignment system employs a dual beam inteferometric method, which takes advantages of higher diffraction efficiency compared with other TTL type alignment systems. As the results, alignment accuracy for OFF-AXIS and TTL alignment system were obtained within 0.1 $\mu\textrm{m}$/ 3 $\sigma$ for the various substrate on the wafers. The wafer focusing and leveling system is modified version of the conventional systems using position sensitive detectors (PSD). This type of detection method showed focusing and leveling accuracies of about $\pm$ 0.1 $\mu\textrm{m}$ and $\pm$ 0.5 arcsec, respectively. From the CD measurement, we obtained 0.4 $\mu\textrm{m}$ resolution features over the full field with routine use, and 0.3 $\mu\textrm{m}$ resolution was attainable under more strict conditions.

• Korean Journal of Materials Research
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• v.10 no.4
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• pp.290-294
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• 2000

ZnS:Mn TFEL devices were fabricated by electron-beam evaporation method and then the electro-optical properties were investigated. To investigate the capacitance which was due to oxygen vacancy at the $Ta_2O_5$ thin film, AES(Auger Electron Spectroscopy) and C-F(capacitance-frequency) measurements were used. It was found that the capacitance was decreased by annealing the $Ta_2O_5$ film in oxygen ambience. From EL emission measurement, we observed the EL emission spectrum which had the peak range from 550nm and 650nm. This emission is associated with the transition from $^4T_1(^4G)$ first excited state to $^6A_1(^6S)$ ground state in the $3d^5$ energy level configuration of $Mn^{2+}$ occurs. The threshold voltage of EL device with $Ta_2O_5$ insulator layer was found to be 24V~28V. The CIE color coordinates of these emission are X=0.5151, Y=0.4202 which is yellowish orange emitting. The EL device using $Ta_2O_5$ insulator layer can be driven with a low voltage which is beneficial to the practical application.

• The Journal of Korean Society for Radiation Therapy
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• v.29 no.1
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• pp.93-101
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• 2017

Purpose: In breast cancer radiotherapy, brass mesh bolus has been recently studied to overcome disadvantage of conventional bolus. The purpose of this study is to investigate the stability of first introduced the brass mesh in the country, and evaluate the skin surface dose of that. Materials and Methods: The measurement of skin surface dose was evaluated to verify similar thickness of the Brass mesh bolus that compared conformal tissue equivalent bolus with 5 mm thickness. We used 6 MV photons on an ELEKTA VERSA linear accelerator and optically stimulated luminescent dosimeter (OSLD). In addition, two opposed beam using IMRT phantom was applied to comparative study of brass mesh bolus between tissue equivalent bolus. Results: The results showed that similar thickness of the Brass mesh bolus was 3 mm compared with 5 mm tissue equivalent bolus by measuring the skin surface dose of solid phantom. The surface dose for IMRT thorax phantom using 3 mm brass mesh bolus was about 1.069 times greater than that using tissue equivalent bolus. Conclusion: In this study, we found that the brass mesh bolus improved better reduction of skin sparing effect and dose uniformity than tissue equivalent bolus. However evaluation for various clinic cases should be investigated.