• Journal of the Korea Convergence Society
• /
• v.8 no.5
• /
• pp.1-11
• /
• 2017

With a given spring-mass-damper system, $H_{\infty}$ and ${\mu}$-synthesis control methods are used to build system controllers which minimize vibrations at two major natural frequencies in two cases; without uncertainty; with 20% uncertainty. In order to check the stability and performance of two controllers, those are examined using GM and PM values. The signal strength of output responses is compared using the concept of central numerical differentiation and then results are quantified using the RMS method. Lastly, 40 random samples of $H_{\infty}$ and ${\mu}$-synthesis controllers are obtained for three different $W_{per\;f1}$ weighting functions and drawn in the time domain in order to compare the stability. Overall, ${\mu}$-synthesis controller manages the vibrations much better than $H_{\infty}$ controller according to the robust stability and performance values obtained by simulating random samples of 40 plant models.

• The Journal of the Korea Contents Association
• /
• v.15 no.6
• /
• pp.267-275
• /
• 2015

This study has been implemented to check the effect of roughness on the color stability according to the surface treatment of artificial teeth. 20 units of 3 groups with the different surface treatment of artificial teeth have been precipitated in the soy sauce, the red pepper paste, the coffee and the cola, measure equipment was used for Shade-eye(Chroma Meter, Shofu, U.S.A). The value of L*, a*, b* using its average value after measuring 3 times per 1 point by selecting 3 points randomly out of central parts of teeth on a cycle of each 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks after precipitation in terms of precipitated specimens. As a result of Multiple regression analysis, the value of ${\Delta}E*$ of artificial teeth according to the surface treatment showed the significant negative(-) effect in the Group 2(p<0.001) and the red pepper paste had the biggest effect on the color change of artificial teeth out of pollution source.

• The Journal of Engineering Geology
• /
• v.20 no.1
• /
• pp.13-23
• /
• 2010

Toppling failure of a slope is defined as failure behavior accompanying the rotation of rock block which is different from other failure such as sliding along with discontinuities and so on. It generally occurs in the region that discontinuities were developed with inverse dip direction to a slope and it could play a critical role in judging stability of slope. In this study, the stability evaluation was performed about toppling failure on a jointed road cut-slope. To check the deformation behavior, numerical analysis is widely used. However common analysis programs are based on continuum model. Recently, many methods that discontinuity properties can be considered in continuum analysis are suggested. In this study, numerical analysis based on FEM(Finite Element Method) was performed using interface element applied in heterogeneous boundary to simulate effects of discontinuities.

• Journal of the Korean Ceramic Society
• /
• v.34 no.6
• /
• pp.652-658
• /
• 1997

The phase stability in the interface of Sr-doped LaMnO3(LSM)/Gd-doped CeO2(CGO) was examined in this study in order to check the feasibility of using LSM as the cathode material in a low-temperature SOFC(solid oxide fuel cell) using CGO as the electrolyte. For the purpose, CGO powders of Ce0.82Gd0.18O0.91 and two LSM powders having different compositions, La0.9Sr0.1MnO3(LSM10) and La0.5Sr0.5MnO3(LSM50), were synthesized using Pechini method. Then, specimens having the LSM/CGO interface were prepared, heat-treated at 130$0^{\circ}C$ for up to 3 days, and analyzed by XRD and STEM/EDX. Face-centered cubic CGO powders of less than 10 nm size were obtained by calcination of polymeric precursor formed in the process at 45$0^{\circ}C$. Higher calcination temperature of $700^{\circ}C$ was necessary for monoclinic LSM10 and cubic LSM50 powders. LSM powders were coarser than CGO and observed to be in the range of 50~100 nm. No trace of LSM-CGO interaction product was found in the XRD pattern. Also it was known from the concentration profile in the vicinity of the interface that interdiffusion was occurred over only a small penetration depth of ~100 nm order.

• Management & Information Systems Review
• /
• v.19
• /
• pp.49-81
• /
• 2006

The private college education plays a crucial role both in training and supplying manpower needed for national economic growth and in increasing employability and personal labor earnings of individual workers. In oder for private college education to effectively respond to the rapid changes in industrial and occupational structures, it is necessary to secure appropriate level of investment funds and manage them efficiently. For this, it is required to discuss the structure, magnitude and management mechanism of the current private college education finance, changes in future demand for private college education and resultant changes in budget estimates, and new financial resources and allocation schemes. This study attempted to analyze current status and problems of private college education finance in Korea and, based on this analysis, to suggest future policy directions to improve private college education finance system. In order to make the private college education system in Korea competent and competitive enough to survive in international market, it is prerequisite to provide enough budget for the private college education and to manage the private college education finance in more efficient ways. First, for securing the adequacy and stability of investment budget for the private college education, it is recommended to 1) increase the government budget and put emphasis on the private college education; 2) diversify financial resources and induce financial contribution from private sector such as school juridical persons and enterprises. Second, for higher efficiency of financial management, it is recommended 1) make valid allocation standards and mechanism; 2) introduce competition system; 3) develop and utilize evaluation mechanism for the private college education finance to check adequacy, efficiency, accountability, and effectiveness; 4) apply consumer-oriented financial management scheme. In addition to the above policy measures, it is necessary to 1) make scientific forecasts of industrial and occupational structures periodically and apply these analyses to medium & long-term the private college education planning; and 2) redesign budget accounting system and develop the private college education performance indicators for the evaluation of accountability of the private college education institutions and administration institutes.

• Atmosphere
• /
• v.24 no.2
• /
• pp.197-206
• /
• 2014

The effects of different averaging operators and atmospheric stability on the turbulent fluxes are investigated using the vertical velocity, air temperature, carbon dioxide concentration, and absolute humidity data measured at 10 Hz by a 3-dimensional sonic anemometer and an open-path $CO_2/H_2O$ infrared gas analyzer installed at a height of 18.5 m on the rooftop of the Jungnang KT building located at a typical residential area in Seoul, Korea. For this purpose, 7 different averaging operators including block average, linear regression, and moving averages during 100 s, 300 s, 600 s, 900 s, and 1800 s are considered and the data quality control procedure such as physical limit check and spike removal is also applied. It is found that as the averaging interval becomes shorter, turbulent fluxes computed by the moving average become smaller and the ratios of turbulent fluxes computed by the 100 s moving average to the fluxes by the 1800 s moving average under unstable stability are smaller than those under neutral stability. The turbulent fluxes computed by the linear regression are 85~92% of those computed by the 1800 s moving average and nearly the same as those computed by 900 s moving average, implying that the adequate selection of an averaging operator and its interval will be very important to estimate more accurate turbulent fluxes at urban area.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.30 no.6
• /
• pp.1147-1151
• /
• 2001

We investigated stabilities of blue pigment extracted from Gardenia jasminoides at various conditions to check its applicability for beverages. Gardenia blue pigment with maximum absorption at 587 nm was obtained from the reaction of glycine and genipin (aglycone of geniposide). The blue pigment was found to be relatively unstable at acidic pH but very stable at alkaline conditions with half-life values of 102 days and 126 days at PH 9.0 and PH 11.0, respectively. The pigment also showed high thermal stability with half-life value of 55, 18, and 2 days at 50, 70, and 9$0^{\circ}C$, respectively. The addition of inorganic ions, sugars, and amino acids to model beverage containing this blue pigment increased retention rate at room temperature while addition of vitamin C decreased the stability. The sensory evaluation of the model beverage showed that inorganic ions and amino acids increased overall acceptability, indicating that the blue pigments of Gardenia jasminoides can be used as a natural colorant for leverage.

• Journal of rehabilitation welfare engineering & assistive technology
• /
• v.4 no.1
• /
• pp.1-8
• /
• 2010

The combination of medical devices and IT convergence technology has made it possible to check health whenever and wherever people want. The recent development of various Ubiqutous Healthcare medical devices ensures the convenient measurements of health variations in daily lives and at home. However, considering that there is a growing prevalence of the devices and a great interest in the development of Ubiqutous Healthcare device, it is urgent to secure the stability and to establish performance evaluation. Therefore, it is needed to develop standard testing methods for the stability and the performance evaluation on before and after selling products. In this paper, I studied the standard testing method of both compulsory tests and performance evaluation which are for the electric stability evaluation on Ubiqutous Healthcare devices.

• 한국지구물리탐사학회:학술대회논문집
• /
• 1999.08a
• /
• pp.217-239
• /
• 1999

Investigation methods of cut slope are conducted generally only geological surface survey to gain engineering geological data of cut slopes. These methods have many problems such as limitation of investigation for a special area. So geophysical investigations such as geotomography, seismic and electrical resistivity methods have been used to search for failure surface in potential failure slopes or failed slopes. But investigation method using the borehole camera is recently a used method and it is thought that this method is more reliable method than other investigation methods because of being able to see by the eyes. Therefore, this paper was conducted investigations of 4 boleholes and BIPS (Borehole Image Processing System) to search for potential sliding surfaces and was applied to obtain information of discontinuity on failed highway slope. As the results of BIPS, we could decide potential sliding surface in the slope and conducted to check slope stability. And decided slope stability measures.

• Journal of Korea Water Resources Association
• /
• v.36 no.4
• /
• pp.623-631
• /
• 2003

A large scale hydrological laboratory model tests for the geotextile tube were conducted to investigate the stability of geotextile tube and the capability of breakwater with variations of significant wave height, percentage of soil filling, and the water level above geotextile tube. The sliding displacement of geotextile tube is measured to check the stability of geotextile tube for given the various significant wane heights. The marked mash was laid out at the bottom of water channel to measure the displacement of geotextile tube. The bench mark was furnished in the upper part of water channel and the initial location was marked every 10cm interval to measure the displacement of geotextile tube. The wane transmit ratios are analyzed with the variations of soil filling of tube and of the top crown height wave above the geotextile tube in order to study the performance of brekwater before and after the installation of geotextile tube.