• ETRI Journal
• /
• v.9 no.2
• /
• pp.55-61
• /
• 1987

The effective cutoff wavelength of $LP_11$mode is measured as a function of fiber length for three types of single-mode optical fiber which have different characteristics in the index profile or the coating structure. The measured cutoff wavelength decreased linearly in a logarithmic scale of fiber length as increasing fiber length, and eventually became constant after 3km for two fiber types. It is found that the length dependence of cutoff wavelength is due to a mode coupling between the $LP_01$ and $LP_11$ modes.

• The Journal of the Korea Contents Association
• /
• v.17 no.11
• /
• pp.515-524
• /
• 2017

This study is focused on finding out how Mers affects tourism industry. To achieve the study purpose we analyzed the differences of management performance of hotels, travel agencies and airlines before and after Mers occurrence. As the result of analysis, there were significant differences in the variables of profit margin ratio before income taxes and operating profit ratio as a profit index before and after Mers occurrence in the hotel firms. And in case of travel agencies, there were significant differences in the variables of debt to equity ratio and borrowings dependence ratio as a stability index before and after Mers occurrence. Lastly there were significant differences in the variables of operating profit ratio as a profit index and total assets turnover ratio as an activity index before and after Mers occurrence in the airlines. Therefore the managers should find an way to reduce the negative image of plague through the effective marketing strategy.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.33 no.2
• /
• pp.447-450
• /
• 2004

Overall migration through epoxy layer coated wood was investigated to estimate the coating thickness satisfying the regulatory limit. As an index of overall migration, KMnO$_4$ oxidizable extractives by the food simulant water solution was used. Migration pattern in interest range could described by a simple diffusion model and the temperature dependence of the permeability index could be explained by Arrhenius equation. The thickness of epoxy coating greater than 0.004 mm was analyzed to be required for satisfying the regulatory guideline.

• Korean Journal of Soil Science and Fertilizer
• /
• v.37 no.3
• /
• pp.192-198
• /
• 2004

The heavy dependence of modern science-based agriculture on chemicals such as fertilizers and pesticides, and heavy machinery gave rise to questions about long-term sustainability of agriculture in relation to degradation of soil quality. The research achievements and trends in developing soil quality indicators were introduced and discussed in this report. Organization for Economic Cooperation and Development (OECD) established 13 agri-environment indicators including soil quality indicator in 1994, collected the soil data and methodologies for development of soil quality indicators in OECD member countries responded to OECD questionnaires and published the OECD reports, Environmental Indicators for Agriculture Volume 1, 2, and 3. Leading countries such as USA, Canada and New Zealand collected national data and evaluated the data in aspect of soil quality. They developed the various methods for selecting a minimum data set (MDS), scoring the soil properties and calculating soil quality index integrating the score of each soil property.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2005.05a
• /
• pp.248-253
• /
• 2005

Although DC ground resistance is a good index of grounding performance for grounding electrodes, it does not reflect the grounding performance during transient state. Besides, impulse ground impedance, which is defined by a ratio of the peak value of transient ground potential rise to the peak value of impulse current, cannot be an absolute index due to its dependence on impulse current shape. In this paper, ground impedance of various rod-type ground electrodes has been measured in frequency domain ranging from 1 Hz to hundreds of kHz. Equivalent circuit models of the ground rod have been identified from the measured values of ground impedance in frequency domain.

• Journal of Korean Ophthalmic Optics Society
• /
• v.1 no.1
• /
• pp.65-72
• /
• 1996

The general property of plastic ophthalmic lens has been reviewed by the optical property and polymer structure. A PMMA which is synthesized by the polymerization of monomers of two or more kinds is termed a copolymer, and the main chain composes a skeleton of molecular structure in the polymer. Refraction index of polymer was governed mainly by the polarization of molecular and was followed to increase it conspicuously as Cl, Br, and Iodine was substitude to hydrogen. Thermal dependence of refraction index of polymer show that the higher distinctive characteristic than glass material.

• Proceedings of the KIEE Conference
• /
• 2005.07a
• /
• pp.694-696
• /
• 2005

Although DC ground resistance is a good index of grounding performance for grounding electrodes, it does not reflect the grounding performance during transient state. Besides, impulse ground impedance, which is defined by a ratio of the peak value of transient ground potential rise to the peak value of impulse current, cannot be an absolute index due to its dependence on impulse current shape. In this paper, ground impedance characteristics of ground electrodes has been measured in frequency domain ranging from 1 Hz to hundreds of kHz. Equivalent circuit models and transfer function models of the ground rod have been identified from the measured values of ground impedance in frequency domain.

• Journal of the Korean institute of surface engineering
• /
• v.34 no.3
• /
• pp.240-246
• /
• 2001

The possibility of using a glass block with the composition of sodium borosilicate as starting materials for GRIN glass was examined from the view points of the phase separation of the matrix glass, the effects of leaching and the heating conditions for a porous structure, and the change in the refractive index. Glass specimens with similar compositions were prepared in the form of porous glass using a phase-separation technique. An examination of the heating and leaching conditions and the microstructure dependence of these conditions was made.; Specimens with porous structure were obtained when the heat treatment and leaching conditions were fixed at $540^{\circ}C$ for 30hrs and in a 0.3N$ H_2$$SO_4$ solution at $100^{\circ}C$, respectively. The resultant specimens had some important features on the GRIN glass.; the depth of the gradient and the change in refractive index (Δn) were 4mm and 0.015~0.02, respectively.

• 한국초전도학회:학술대회논문집
• /
• v.14
• /
• pp.81-81
• /
• 2004

• 한국초전도학회:학술대회논문집
• /
• v.14
• /
• pp.40-40
• /
• 2004