• 대한전기학회논문지:전력기술부문A
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• 제49권2호
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• pp.78-84
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• 2000

This paper introduces a method of determining the maximum real power transfer limit of interface lines, which connect two areas of a power system, using locally parameterized continuation algorithm. This method traces the path of power flow solutions as interface flow is gradually increased under a certain load demand condition and finds the steady state voltage stability limit, the interface flow limit. Voltage stability index is used to indicate how close the maximum limit is reached. Also, this study presents a procedure to determine the security-constrained interface flow limit using the above method. Contingency ranking index is proposed to identify the severity of contingencies. The case study is performed according to the suggested procedure.

• Journal of Welding and Joining
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• 제16권4호
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• pp.125-135
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• 1998

The shielded metal arc welding (SMAW) by AC power source was performed to evaluate the arc stability by arc monitoring and analysing. In this study, the arc stability index was evaluated quantitatively by using he coefficient of resistance variation for welding time. This coefficient was obtained for the long time (20sec.) by analysing the waveforms of welding current, voltage and resistance. The coefficient was applied to indicate numerically the variation level of arc length and the degree of arc extinction. Using the coefficient of resistance variation in practical welding, the arc stability of the high titanium oxide electrode (KS E4313) turned out to be better than that of the low hydrogen electrode (KS E4316). In evaluating the skill level of welders by the coefficient, the horizontal fillet weaving welding became clear to be very discriminating because the higher level welder could weave in keeping constant arc length, but the lower level welder showed the characteristics of weaving with the unstable arc length. And it was confirmed that the welding defects as blow holes was formed when the arc stability index were high.

• 아동학회지
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• 제27권1호
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• pp.153-166
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• 2006

Stability of the Korean Bayley Scale of Infant Development-II was tested in 305 infants by two measurements of varying intervals over a span of 5-36 months. Stability of K-BSID-II performance was r=.62(p<.01), r=.08(p<.18), r=.69(p<.01), r=.18(p<.01) for mental scale raw scores, mental scale index scores (MDI), psycho-motor scale raw scores and psycho-motor scale index scores(PDI), respectively. Stability was higher for the shorter test-retest interval group. Correlations between raw scores among infants with retest intervals of more than 2 years were stable on both mental and psycho-motor scales. MDI showed higher stability among high-risk infants than normal infants while PDI showed higher stability among normal infants. Testers and researchers should use both raw scores and index scores for better interpretations.

• 대한수학회논문집
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• 제11권4호
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• pp.959-965
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• 1996

In this paper we study the index stability theorem for a bounded linear operator with closed range and extend the Kato's decomposition theorem for an absence of the index.

• 대기
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• 제23권4호
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• pp.443-452
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• 2013

The original Fog Stability Index (FSI) is formulated as FSI=$2(T-T_d)+2(T-T_{850})+WS_{850}$, where $T-T_d$ is dew point deficit (temperature-dew point temperature), $T-T_{850}$ is atmospheric stability measure (temperature-temperature at 850 hPa altitude) and $WS_{850}$ is wind speed at 850 hPa altitude. As a way to improve fog prediction at Incheon International Airport (IIA), we develop the modified FSI for IIA, using the meteorological data at IIA for two years from June 2011 to May 2013, the first one year for development and the second one year for validation. The relative contribution of the three parameters of the modified FSI is 9: 1: 0, indicating that $WS_{850}$ is found to be a non-contributing factor for fog formation at IIA. The critical success index (CSI) of the modified FSI is 0.68. Further development is made to consider the fact that fogs at IIA are highly influenced by advection of moisture from the Yellow Sea. One added parameter after statistical evaluation of the several candidate parameters is the dew point deficit at a buoy over the Yellow Sea. The relative contribution of the four parameters (including the new one) of the newly developed FSI is 10: 2: 0.5: 6.4. The CSI of the new FSI is 0.50. Since the developmental period of one year is too short, the FSI should be refined more as the data are accumulated more.

• 한국환경복원기술학회지
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• 제24권3호
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• pp.33-47
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• 2021

This study was conducted to investigate the influence of eco-friendly restoration in forested bog on the structure of benthic macroinvertebrate community. The benthic macroinvertebrates collected from the surveyed sites were composed of 1,071 individuals, 60 species, 40 families, 13 orders, 6 classes and 5 phyla. At the control and Site 3(small dam), the number of species and individuals were larger than that of other sites, and EPT group ratio was same as well. Considered by index, the dominance index (DI) was found the highest at the biotope area. The diversity index (H') and richness index (RI) were the highest at the control and Site 3. In addition, the ecological score of benthic macroinvertebrate (ESB) showed the highest at site 3, while the lowest at biotope area. The stability and recovery of benthic macrointebrates showed different according to restoration types at forested bog. After restoration project, the benthic macroinvertebrates were observed to get recovery at Site 3, and to have the highest communities stability at control and Site 3. At biotope areas (Site 4, Site 5 and Site 6) communities stability were the lowest, but showed different community stability values according to the presence of water. It is confirmed that the eco-friendly restoration projects indeed provided the better environment for the inhabitation of benthic macroinvertebrate community. The change of community index depending on the restoration projects suggests that the eco-friendly restoration can provide a more suitable environment for benthic macroinvertebrate ecosystem that prefers the stream environment.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1110-1122
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• 2018

This paper proposes an alternative method to evaluate the effect of wind power to the power system stability with small disturbance. Alternatively, available techniques for stability analysis of a power system based on deterministic methods are less accurate for high penetration of wind power. Numerical simulations of random behaviors are computationally expensive. A stochastic stability index (SSI) is proposed for the power system stability evaluation based on the theory of stochastic stability and energy function, specifically the stochastic derivative of the relative well-defined energy function and the critical energy. The SSI is implemented on the modified nine-bus system including wind turbines under different conditions. A doubly-fed induction generator (DFIG) wind turbine is characterized and modeled using measured wind data from several sites in Thailand. Each of the obtained wind power data is analyzed. The wind power effect is modeled considering the aggregated effect of wind turbines. With the proposed method, the system behavior is properly predicted and the stability is quantitatively evaluated with less computational effort compared with conventional numerical simulation methods.

• 대한가정학회지
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• 제44권2호
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• pp.103-112
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• 2006

This study followed the standardization study pool of K-BSID-II to examine the stability of K-BSID-II. One hundred and ninety five infants aged from 1-42 months tested twice with intervals of 5-16 month between tests. All participants had been full-term babies without any medical complications. There were no significant differences between the groups which were divided in terms of demographic variables such as mothers' education, infants' birth order and gender. The stability of K-BSID-II was significant and that of the mental scale was lower than that of the psycho-motor scale: There were high stabilities between raw scores in two sessions(r=.91 for the mental scale and r=.89 for the psycho-motor scale) but there were significant but low correlations between mental index scores(r=.18, p<.05) and psycho-motor index scores(r=.17, p<.05). The stability was increased with initial test age and mothers' education. It was recommended for testers and researchers to use both raw scores and index scores for better interpretations in future research.

• The Journal of Asian Finance, Economics and Business
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• 제7권10호
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• pp.629-639
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• 2020

The current study explains how corruption, terrorism, political stability and oil price has an effect on on the Iraq stock exchange utilizing corruption perception index as a proxy of corruption, global terrorism index as proxy for terrorism, political stability and oil price with ISX60 index as proxy of stock market for the period (2005-2019) using Ordinary Least Square method. The results show that the level of corruption, terrorism activities and political stability coefficient is significantly positive with Iraq stock exchange. In contrast, the oil price coefficient is significantly negative with Iraq stock exchange, which means that lower levels of corruption, less terrorism activities and more stability in political system have strong influence on stock market development in Iraq. The study concludes that the explanatory variables are important for Iraq stock exchange. Hence, the study suggests the policy makers to develop stock market by implementing policies and strategies to overcome high level of corruption, terrorism activities especially after ISIS/ISIL announcement has been made public. There is a need for transparency and creating stable political environment through good governance practices in order to attract more foreign investment and promote economic development. Factors like terrorism and corruption make economic and political systems unstable and has an adverse effect on on Iraq's stock exchange performance.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.782-789
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• 2010

Landslides cause enormous economic losses and casualties. Korea has mountainous regions and heavy slopes in most parts of the land and has consistently built new roads and large-scale housing complexes according to its industrial and urban growth. As a result, the damage from landslides becomes greater every year. In this study, performed a GIS-based landslide hazard analysis by SINMAP(Stability Index MAPping) model in Gyeonggi Icheon area coupling with geomorphological and geological data. SINMAP model has its theoretical basis in the infinite plane slope stability model with wetness obtained from a topographically based steady state model of hydrology. To Gyeonggi Icheon area landslides hazards evaluated, these SINMAP model were analysed results while simultaneously referring to the stability index map, where lines distinguish the zones categorized into the different stability classes and a table giving summary statistics.