• The korean journal of orthodontics
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• v.34 no.4 s.105
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• pp.351-362
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• 2004

Orthodontic band cements are widely used in the fields of orthodontics, but they are commonly known as cytotoxic material. Within an oral cavity several ions and components are released from orthodontic band cements, thus causing inflammation or injury to the Periodontal tissue. Therefore, it is very important to estimate the biocompatibility of orthodontic band cements. The purpose of this study was to assess the cytotoxic effect of orthodontic band cements to HGF cells. A zinc phosphate cement, a glass ionomer, a resin modified glass ionomer, and compomer were used to evaluate three cytotoxicity assays: cell proliferation assay, MTT assay, and agar ovelay assay The results were as follows: 1. In the cell proliferation assay, Gl>ZPC, RMGI, RMGI24, GI24>compomer24, ZPC24, compomer>metal ring lined up in order of cytotoxicity 2. In the MTT assay, GI>ZPC, RMGI>GI24>ZPC24, compomer, metal ring, RMGI24, compomer24 lined up in order of cytotoxicity. 3. In the agar overlay test, GI>GI24, ZPC, ZPC24, RMGI>RMGI24, compomer, compomer24, metal ring lined up in order of cytotoxicity.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.7
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• pp.682-687
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• 2011

Calibration mirror mechanism has been widely used for on-board calibration with black body. The calibration mirror is deployed to reflect the radiation energy from the black body to the image sensor for calibrating the sensor system. After the calibration, the calibration mirror is stowed not to hide a main optical path. It also has a fail-safe function which can stow the mirror by just removing the input power of motor when the calibration mirror is stopped at certain position during the calibration. In the present work, the operation concept, design, torque analysis and functional test results of the calibration mirror mechanism with the aforementioned function have been introduced and investigated.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.2
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• pp.183-188
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• 1993

This experiment was conducted to investigate the effect of sulfur containing fertilizers on growth, yield and nutritive quality of soybean as affected by lime application at reclaimed soil. Lime application for neutralization requirements showed the effect of increased grain yield about 32% compared to the non application at newly opened land of red and yellow soil. In case of lime application, the sulfur containing fertilizers combined with super phosphate, ammonium sulfate, and gypsum increased the grain yield by 31%, 11%, and 3%, respectively. When lime was not applied, magnesium carbonate application increased the yield by 47%, super phosphate by 22%, and gypsum by 15%. The protein content of grain was higher at lime application than those of non lime application and was increased by the application of sulfur containing fertilizer. But lipid content was not affected by lime or sulfur application. From the above results obtained it was concluded that sulfur fertilizer effect under lime application was significant when combined with super phosphate or ammonium sulfate application. Magnesium carbonate or super phosphate application was the best combination with sulfur-containing fertilizer.

• The Journal of the Korea Contents Association
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• v.10 no.9
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• pp.309-317
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• 2010

The stainless steel wire is extensively used for the orthodontic treatment. But, the stainless steel wire that has commonly superior corrosion resistance has caused hypersensitive reaction or allergy as side effects because of corrosion in the oral environment. For improving the problem of corrosion, we was evaluated the suitability of the duplex stainless steel(DSS) as orthodontic wire through this study. The DSS wire was evaluated the mechanical strength and bio-stability for suitability and bio-compatibility as orthodontic wire. In this work, the DSS and stainless steel(SS) as common use of medical grade were prepared for the tensile strength test. The DSS wire were treated by heat. and Temperature conditions of the heat treatment were $28^{\circ}C$, $500^{\circ}C$, $600^{\circ}C$, $700^{\circ}C$, $800^{\circ}C$, $900^{\circ}C$, respectively. And the DSS wires that treated by heat on the optimum temperature condition were conducted the bending moment test and calculated the S-Max value and the modulus of elasticity. For evaluating the bio stability, each materials were conducted in vitro test for measuring the cell survival rate. The most interesting results was that the tensile strength test of SS wire($8.17\times10^4\;N/mm^2$) and DSS wire($8.05\times10^4\;N/mm^2$) that treated at $500^{\circ}C$ by heat were similar in mechanical strength. In the bio-stability study, the DSS has no cytotoxicity (p=0.05) Thus, we could make a conclusion that the duplex stainless steel wire has vastly superior corrosion resistance was suitable as orthodontic wire.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1188-1191
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• 2017

Thrust is one of the crucial performance parameter of a combustion chamber in the combustion chamber development test. So it is very important to measure an accurate thrust. Thrust calibration test was performed to identify the system characteristics, resistance and linearity of a vertical thrust measurement system(TMS) for accurate thrust measurement. It has been found 6.9% ~ 8.6% errors between the measured thrust by TMS calibration equations and theoretical thrust. It has been confirmed that the TMS calibration is necessary to be performed with the propellant lines connected to the combustion chamber for accurate thrust measurement.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1221-1229
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• 2014

This paper proposes an approach for predicting the fatigue life of a propeller shaft of a forklift truck by an accelerated life test method. The accelerated life test method adopted in this study is the calibrated accelerated life test, which is highly effective in the prediction of the lifetime and enables significant reduction of the test time as well as a quantification of reliability in the case of small sample sizes. First, the fatigue test was performed under two high stress levels, and then, it was performed by setting low stress levels in consideration of the available test time and extrapolation. Major reliability parameters such as the lifetime, accelerated power index, and shape parameter were obtained experimentally, and the experimentally predicted lifetime of the propeller shaft was verified through comparison with results of an analysis of load spectrum data under actual operating conditions.

• 치위협보
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• s.40
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• pp.1-8
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• 2000

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.1 s.61
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• pp.43-50
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• 2007

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.1
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• pp.25-30
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• 2010

Purpose: This study was conducted to estimate the changes of corrected diopter and corrected visual acuity with the change in vertex distance. Also we aimed to provide basic data for refraction test. Methods: Using the trial lens, we measured the corrected diopter and corrected visual acuity after performing binocular balance test. We measured the changes of corrected diopter and corrected visual acuity in change of vertex distance. We analyzed statistical significance and relations between vertex distance and corrected diopter and corrected visual acuity. Results: There was no difference in corrected diopter with the change of vertex distance within -1.00D, but the corrected diopter increased with it over - 1.25D. In particular, the change of diopter was largest when the vertex distance increased 15 mm. At over 11.00D, there was large changes of diopter with the changes of vertex distance at 5 mm, 10 mm and 15 mm. On correlation analysis between the vertex distance and the corrected diopter, there was strong correlation (r=0.999 at 5 mm increase of vertex distance, r=0.982 at 10 mm increase and r=0.957 at 15 mm increase) and also there was significant (p<0.01). At the change of visual acuity in increased of vertex distance, the range of a decrease in visual acuity was large when the changes of vertex distance was largest. On correlation analysis between the vertex distance and the corrected visual acuity, there was strong correlation (r=0.969 at 5 mm increase of vertex distance, r=0.985 at 10 mm increase and r=0.994 at 15 mm increase) and also there was significant (p<0.01). Conclusions: The vertex distance was very important at the refraction test and at wearing spectacle. On correlation analysis between the vertex distance and the corrected diopter, and the corrected visual acuity, there was strong correlation and statistically significant. Therefore, the vertex distance should be kept at the refraction using trial lens, and the best fitting was made not to slipping forward, and so we suggested regular refitting of spectacle and the managing method of spectacle were educated to the spectacle wearers.

• Journal of Astronomy and Space Sciences
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• v.19 no.4
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• pp.293-304
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• 2002

This paper describes the re-design and the calibration results of the MAG digital circuit onboard the KSR-3. We enhanced the sampling rate of magnetometer data. Also, we reduced noise and increased authoritativeness of data. We could confirm that AIM resolution was decreased less than InT of analog calibration by a digital calibration of magnetometer. Therefore, we used numerical-program to correct this problem. As a result, we could calculate correction and error of data. These corrections will be applied to magnetometer data after the launch of KSR-3.