• Earthquakes and Structures
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• 제10권2호
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• pp.329-350
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• 2016

A parametric study was conducted to investigate the seismic deformation demands in terms of drift ratio, plastic base rotation and compression strain on rectangular wall members in frame-wall systems. The wall index defined as ratio of total wall area to the floor plan area was kept as variable in frame-wall models and its relation with the seismic demand at the base of the wall was investigated. The wall indexes of analyzed models are in the range of 0.2-2%. 4, 8 and 12-story frame-wall models were created. The seismic behavior of frame-wall models were calculated using nonlinear time-history analysis and design spectrum matched ground motion set. Analyses results revealed that the increased wall index led to significant reduction in the top and inter-story displacement demands especially for 4-story models. The calculated average inter-story drift decreased from 1.5% to 0.5% for 4-story models. The average drift ratio in 8- and 12-story models has changed from approximately 1.5% to 0.75%. As the wall index increases, the dispersion in the calculated drifts due to ground motion variability decreased considerably. This is mainly due to increase in the lateral stiffness of models that leads their fundamental period of vibration to fall into zone of the response spectra that has smaller dispersion for scaled ground motion data set. When walls were assessed according to plastic rotation limits defined in ASCE/SEI 41, it was seen that the walls in frame-wall systems with low wall index in the range of 0.2-0.6% could seldom survive the design earthquake without major damage. Concrete compressive strains calculated in all frame-wall structures were much higher than the limit allowed for design, ${\varepsilon}_c$=0.0035, so confinement is required at the boundaries. For rectangular walls above the wall index value of 1.0% nearly all walls assure at least life safety (LS) performance criteria. It is proposed that in the design of dual systems where frames and walls are connected by link and transverse beams, the minimum value of wall index should be greater than 0.6%, in order to prevent excessive damage to wall members.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2759-2764
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• 2003

Humans usually employ more joints than they actually need, and thus they can be categorized as a kinematically redundant system. Therefore, the behavior of the human body can be analyzed by several redundancy resolution algorithms. Different from typical industrial robots that are fixed to the ground, the COG/ZMP condition should be taken into account in the human body motion in order not to fall down. Thus a COG/ZMP stability index is employed as a measure of stability. Kinematic redundancy inherent in the human body can be exploited to satisfy the COG/ZMP condition. Simulation result shows that the COG/ZMP condition can be satisfied by exploiting the null space motion of the kinematically redundant human body model.

• 한국물환경학회지
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• 제32권1호
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• pp.1-14
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• 2016

This study was conducted to develop a Benthic macroinvertebrates streambed index (BMSI) based on the response of the community to the substrate type of streambed. Analyzing the seasonal (Spring and Fall) data (11,367 sampling units) surveyed and collected during 2008~2014 at 960 sites in South Korea, we estimated the lithophility of 191 taxa. BMSI was composed of the lithophilic value, indicator weight value and individual abundance frequency. It showed an extremely significant correlation (r = -0.8, p<0.001) with the mean grain size (in phi-value) of the streambed.

• 한국환경생물학회:학술대회논문집
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• 한국환경생물학회 2004년도 학술대회
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• pp.24-24
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• 2004

This study was investigated to the seasonal variation of attached diatoms communities in the Hantan River in November 2001, February, Ma and August 2002. It was identified the total 107 taxa which were composed of 95 species, 11 varieties and 1 unidentified speCies. The standing crops ranged 298,5004,776,000cells${\cdot}cm^{-2}.$and showed marked irregularly seasonal variations. It was higher value at the lower station than the upper station in fall. But it was similar values from the upper to the lower station by the effect of typhoon in summer. Chlorophyll concentrations ranged $13.4~304.2{\mu}m{\cdot}cm^{-2}.$ Standing crops and chlorophyll showed similar trends during investigation. Low diversity index values probably indicated the effects of envi~onmental stresses(water temperature, flow and current velocity) other than organic pollution. An assessment of organic pollution using epilithic diatoms(DAlpo) was $\alpha$-oligosaprobic states at the upper and mid stations, and was $\alpha$-mesosaprobic states at the lower stations.

• Journal of the Korean Statistical Society
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• 제27권3호
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• pp.289-303
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• 1998

For square contingency tables with ordered categories, Tomizawa (1995) considered two kinds of measures to represent the degree of departure from global symmetry, which means that the probability that an observation will fall in one of cells in the upper-right triangle of square table is equal to the probability that the observation falls in one of cells in the lower-left triangle of it. This paper proposes a generalization of those measures. The proposed measure is expressed by using Cressie and Read's (1984) power divergence or Patil and Taillie's (1982) diversity index. Special cases of the proposed measure include TomiBawa's measures. The proposed measure would be useful for comparing the degree of departure from global symmetry in several tables.

• 해양환경안전학회지
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• 제3권2호
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• pp.51-61
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• 1997

The in situ observations and the seawater analyses were conducted in July and Auguse, 1996 for the purpose of evaluating the characteristics of seawater quality centered about eutrophication in Mokpo harbour. By applying the OECD standards of trophic classification to the parameters such as secchi depth, total inorganic nitrogen, phosphate phosphorus and chlorophyll-a, the trophic level of seawater in Mokpo harbour was evaluated to be in eutrophic state in summer. The estimation of pollution index by eutrophication showed the seawater quality of Mokpo harbour to deteriorate and fall under the regular grades. The results of eutrophic index estimation showed the high otentiality of red tide occurrence in Mokpo harbour.

• International Journal of Advanced Culture Technology
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• 제11권2호
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• pp.358-365
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• 2023

As the Internet is used as a major channel for marketing and sales, the top ranking of search engine results is becoming a key competitor among websites. Various methods exist to maintain the top ranking of websites in search engines, typically investing heavily in organic coding or search engine optimization. The purpose of this paper, we present the ranking by recognizing factors that should be removed as negative factors when designing a web page in consideration of website visibility (SEO) because if website visibility is not met, the ranking may fall behind or be completely removed from the search engine index. The experiments that recognized and ranked the negative factors of website visibility proposed in this paper were provided through theory and experiments based on the existing website visibility analysis model. The models analyzed in this paper, we expressed or quantified as scores based on the methodology of each model, and 10 items were selected as negative factors through experiments and ranked as high scores. Therefore, when designing a website, it should be considered that the website is not removed from the search engine index as it is designed by excluding high-ranking items, which are negative factors.

• 천문학회보
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• 제35권1호
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• pp.30.2-30.2
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• 2010

Numerous operational anomalies and satellite failures have been reported since the beginnings of the "space age". Space weather effects on modern spacecraft systems have been emphasized more and more as increasing their complexity and capability. Energetic particles potentially can destroy and degrade electronic components in satellites. We analyzed the geostationary (GEO) satellite anomalies during 1997-2009 to search possible influences of space weather on the satellite anomalies like power problem, control processor problem, attitude control problem, etc. For this we use particle data from GOES and LANL satellites to investigate space weather effects on the GEO satellites' anomalies depending on Kp index, local time, seasonal variation, and high-energy electron contribution. As results, we obtained following results: (1) there is a good correlation between geomagnetic index(Kp) and anomaly occurrences of the GEO satellite; (2) especially during the solar minimum, occurrence of the satellite anomalies are related to electron flux increase due to high speed solar wind; (3) satellite anomalies occurred more preferentially in the midnight and dawn sector than noon and dusk sector; (4) and the anomalies occurred twice more in Spring and Fall than Summer and Winter; (5) the electron with the lowest energy channel (50-75keV) has the highest correlation (cc=0.758) with the anomalies. High association between the anomalies and the low energy electrons could be understand by the facts that electron fluxes in the spring and fall are stronger than those in the summer and winter, and low-energy electron flux is more concentrated in the dawn sector where the GEO satellite anomalies occurred more frequently than high-energy electron flux. While we could not identify what cause such local time dependences, our results shows that low-energy electrons (~100keV) could be main source of the satellite anomaly, which should be carefully taken into account of operating satellites.

• 한국물환경학회지
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• 제36권1호
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• pp.1-13
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• 2020

The purpose of this study was to investigate the thermal and chemical stratification in Lake Paldang 2013-2018 weekly using Schmidt's stability index (SSI) and the index of chemical stratification (IC-i). The annual average for SSI was 19.1 g cm/㎠ with the maximum value of 45.3 g cm/㎠ in the summer and the minimum value of 4.8 g cm/㎠ in fall-winter showing seasonal differences as well as increased vertical mixing in the summer. The lake stability increased higher in 2016 as compared with the other period. The most influential factors of thermal stratification were temperature and heavy rainfall. Especially, high water temperature and a prolonged residence duration caused by reduced rainfall and inflows could result in an increase of the stratification period. While decreasing inflow and outflow at the end of the rainfall, the thermal stratification was restrengthened within 7-14 days, and then stabilized rapidly before the rainfall. IC-DO increased with high air temperature in the spring and fall-winter. However increasing sunshine duration and residence time and decreasing rate of outflow caused an increase of IC-DO in the summer. Rainfall (less than 800 mm/year) and discharge (less than 200 CMS) significantly declined in 2015 resulting in IC-DO (0.77) increased more than three times over the other years and bottom water hypoxia occurred. The SSI and IC-i used in this study could be applied to other lakes to understand changes in stratification and mixing dynamics.

• 대한원격탐사학회지
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• 제32권1호
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• pp.1-11
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• 2016

Since forest is an important part of ecological system, the deforestation is one of global substantive issues. It is generally accepted that the climate change is related to the deforestation. The issue is worse in developing countries because the forest is one of important natural resources. In the case of North Korea, the deforestation is on the rise from forest reclamation for firewood collection and food production. Moreover, a secondary effect from flood intensifies the damage. Also, the political situation in North Korea presents difficulty to have in-situ measurements. It means that the accurate information of North Korea is nearly impossible to obtain. Thus, assessing the current situation of the forest in North Korea by indirect method is required. The objective of this study is to monitor the forest status of North Korea using multitemporal Landsat images, from 1980s to 2010s. Since the deforestation in North Korea is caused by local residents, we selected two study areas of high population density: Pyeongyang and Hyesan. In North Korea, most of clean Landsat images are acquired in fall season. The fall images have an advantage that we can easily distinguish agriculture areas from forest areas, also have an disadvantage that the forests cannot be easily identified because some of trees have turned red. To identify the forests exactly, we proposed a modified Normalized Difference Vegetation Index (mNDVI) value. The deforestation in Pyeongyang and Hyesan was analyzed by using mNDVI. The dimension of forest has decreased approximately 36% in Pyeongyang for 27 years and approximately 25% in Hyesan for 16 years. The results show that the forest areas in Pyeongyang and Hyesan have been steadily reduced.