• ALGAE
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• v.19 no.4
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• pp.329-337
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• 2004

Monthly variations of phytoplankton communities were conducted to the investigation at five stations in mid and lower parts of the Nakdong River from December 1995 to November 1996. The phytoplankton communities were identified a total 456taxa which were composed of 136 genera, 427 species, 27 varieties and 2 forma. The standing crops of phytoplankton communities ranged from 2.7 to 52.8 (${\times}$10³)cells·ml$^{-1}$ during the investigation periods. Bacillariophyceae was the dominant classes at all stations. The dominant species were 7taxa and the standing crops of these ranged from 18.3 to 95.1% of the standing crops of phytoplankton communities. The dominant species in the mid parts (st. 1, 2) of this river system were benthic species such as Navicula gregaria, N. viridula var. rostellata and Nitzschia palea, however it was planktonic species (Stephan discus hantzschii, Golenkinia radiata) and meroplanktonic species (Aulacoseira ambigua, A. granulata) in the lower parts (st. 3, 4, 5). The seasonal variations of the dominant species in the lower parts were appeared to the planktonic species (S. hantzschii) from winter to spring, and were the meroplanktonic species (A. ambigua and A. granulata) in from summer to fall. The lower parts of the Nakdong river were entropic states because the dominant species were composed A. ambigua, A. granulate and S. hantzschii which were indicators of entropic water quality. The interrelationships between total standing crops and environmental factors(water temperature, pH, NH$_4$, NO$_2$, NO$_3$ and PO$_4$) were low positive or negative coefficients. S. hantzschii had low positive or negative relations with water temperature, NH$_4$, NO$_2$, NO$_3$ and PO$_4$. As the result, the variations of standing crops of phytoplankton were not caused by a single factor but controlled by the complex factors.

• Ocean and Polar Research
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• v.24 no.1
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• pp.19-31
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• 2002

Precipitation variability around King Sejong Station related with E1 $Ni\~{n}o$/Southern Oscillation (ENSO) is evaluated using the gauge-based monthly data of its neighboring stations. Though three Ant-arctic Stations of King Sejong (Korea), Frei (Chile), and Artigas (Uruguay) are all closely located within 10 km, their precipitation data show mostly insignificant positive or rather negative correlations among them in the annual, seasonal and monthly precipitation. This result indicates that there are locally large variations in the distribution of precipitation around King Sejong Station. The monthly data of Frei Station for 31 years (1970-2000) are analyzed for examining the ENSO signal in precipitation because of its longer precipitation record compared to other two stations. From the analysis of seasonal precipitation, it is seen that there is a tendency of less precipitation than the average during E1 $Ni\~{n}o$ events. This dryness is more distinct in fall to spring seasons, in which the precipitation decreases down to about 30% of seasonal mean precipitation. However, the precipitation signal related with La $Ni\~{n}a$ events is not significant. From the analysis of monthly precipitation, it is found that there is a strong negative correlation during 1980s and in the late 1990s, and a weak positive correlation in the early 1990s between normalized monthly precipitation at Frei Station and Sea Surface Temperature (SST) anomalies in the $Ni\~{n}o$ 3.4 region. However, this relation may be not applied over the region around King Sejong Station, but at only one station, Frei.

• ALGAE
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• v.27 no.3
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• pp.215-224
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• 2012

Growth dynamics of the seagrass, Zostera marina were examined at the two stations (Myungju and Dagu) in Jindong Bay on the southern coast of Korea. Eelgrass leaf productivities, underwater irradiance, water temperature, dissolved inorganic nitrogen (DIN) in water column and sediments, and tissue carbon (C) and nitrogen (N) content were monitored monthly from March 2002 to January 2004. Underwater irradiance fluctuated highly without a clear seasonal trend, whereas water temperature showed a distinct seasonal trend at both study stations. Water column DIN concentrations were usually less than $5{\mu}M$ at both study sites. Sediment pore water $NH_4{^+}$ and $NO_3{^-}+NO_2{^-}$ concentrations were higher at the Myungju site than at the Dagu site. Eelgrass leaf productivity at both study sites exhibited a distinct seasonality, increasing during spring and decreasing during summer. Seasonal variation of eelgrass productivity was not consistent with seasonal patterns of underwater irradiance, or water temperature. Eelgrass tissue C and N content at both study sites also showed significant seasonal variations. Relationships between tissue C and N content and leaf productivities exhibited usually negative correlations at both study sites. These negative correlations implied that the growth of Z. marina at the study sites was probably limited by C and N supplies during the high growth periods.

• Journal of Fashion Business
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• v.19 no.2
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• pp.103-117
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• 2015

The purpose of this study was to examine the uniform image of Korean herbal cosmetic brands amongst Korean and Chinese consumers. This study would enable us to explore a BI strategy to enhance international competitiveness of Korean herbal cosmetics brands. The results were as follows. The key words of BI pursued by Sulwhasoo were dignified, novel, graceful, soft, gaily, natural, Korean, modern, and international. Korean people felt that the uniform was graceful and soft, which accorded with Sulwhasoo BI, but also it was trite and dingy, indicating a negative and opposing image. On the other hand, Chinese people felt that the uniform was dignified, novel, graceful, natural, modern, and international, indicating that it matched with Sulwhasoo BI. In The History of Whoo, the key words of BI pursued by the brand were precious, soft, gorgeous, gaily, and natural. The Koreans felt that the uniform was intelligent, and decent, but conversely, it was also austere and dingy, indicating a negative image. The Chinese felt that the uniform was common, hard, austere, dingy, and unnatural, indicating an opposing image to BI. Finally, a uniform design was developed to improve on its problems, establish The History of Whoo's brand identity, and its brand image. First of all, 'The Quintessence : noble passion' was set up as a developmental concept. The textiles, clothing, and accessories were designed using the symbolic elements from The History of Whoo as a motif. Uniforms were developed for spring, fall, and summer.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.4
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• pp.177-183
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• 2015

Incremental sheet metal forming is a manufacturing process to produce thin parts using sheet metals by a series of small incremental deformation. The process rarely needs dedicated dies and molds, thus, preparation time for the process is relatively short as to be compared to conventional metal forming. Spring back in sheet metal working is very common, which causes critical errors in dimensions. Incremental sheet metal forming is not fully investigated yet. Hence, incremental sheet metal forming frequently produces inaccurate parts. This paper proposes a method to minimize dimensional errors to improve shape accuracy of products manufactured by incremental forming. This study conducts experiments using an exclusive incremental forming machine and the material for these experiments are sheets of aluminum AL1015. This research defines a process parameter and selects a few factors for the experiments. The parameters employed in this paper are tool feed rate, tool diameter, step depth, material thickness, forming method, dies applied, and tool path method. In addition, their levels for each factor are determined. The plan of the experiments is designed using orthogonal array $L_8$ ($2^7$) which requires minimum number of experiments. Based on the measurements, dimensional errors are collected both on the tool contacted surfaces and on the non-contacted surfaces. The distances between the formed surfaces and the CAD models are scanned and recorded using a commercial software product. These collected data are statistically analyzed and ANOVAs (analysis of variances) are drawn up. From the ANOVAs, this paper concludes that the process parameters of tool diameter, forming depth, and forming method are the significant factors to reduce the errors on the tool contacted surface. On the other hand, the experimental factors of forming method and dies applied are the significant factors on the non-contacted surface. However, the negative forming method always produces better accuracy than the positive forming method.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.4
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• pp.81-94
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• 2006

The water quality impacts of forest fragmentation at the Doam-dam watershed were evaluated in this study. For this ends, the watershed scale model, Soil and Water Assessment Tool (SWAT) model was utilized. To exclude the effects of different magnitude and patterns in weather, the same weather data of 1985 was used because of significant differences in precipitation in year 1985 and 2000. The water quality impacts of forest fragmentation were analyzed temporarily and spatially because of its nature. The flow rates for Winter and Spring has increased with forest fragmentations by $8,366m^3/month$ and $72,763m^3/month$ in the S1 subwatershed, experiencing the most forest fragmentation within the Doam-dam watershed. For Summer and Fall, the flow rate has increased by $149,901m^3/month$ and $107,109m^3/month$, respectively. It is believed that increased flow rates contributed significant amounts of soil erosion and diffused nonpoint source pollutants into the receiving water bodies. With the forest fragmentation in the S1 watershed, the average sediment concentration values for Winter and Spring increased by 5.448mg/L and 13.354mg/L, respectively. It is believed that the agricultural area, which were forest before the forest fragmentation, are responsible for increased soil erosion and sediment yield during the spring thaw and snow melts. For Spring and Fall, the sediment concentration values increased by 20.680mg/L and 24.680mg/L, respectively. Compared with Winter and Spring, the increased precipitation during Summer and Fall contributed more soil erosion and increased sediment concentration value in the stream. Based on the results obtained from the analysis performed in this study, the stream flow and sediment concentration values has increased with forest fragmentation within the S1 subwatershed. These increased flow and soil erosion could contribute the eutrophication in the receiving water bodies. This results show that natural functionalities of the forest, such as flood control, soil erosion protection, and water quality improvement, can be easily lost with on-going forest fragmentation within the watershed. Thus, the minimize the negative impacts of forest fragmentation, comprehensive land use planning at watershed scale needs to be developed and implemented based on the results obtained in this research.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.3
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• pp.36-45
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• 2010

To analyze the relationship between climatic factors (monthly mean temperature and total precipitation) and tree-ring growths of Quercus mongolica Fischer (Mongolian oak) with different topographic sites in Mt. Worak, more than 10 trees were selected from each of seven stands. Two cores from each tree were measured for ring width. After crossdating, each ring-width series was double standardized by fitting first a negative exponential or straight regression line and secondly a 60-year cubic spline. Seven stands were categorized in two groups using cluster analysis for tree-ring index patterns. Cluster I (four stands) was located in higher elevation (550-812 m) with aspects of east, west and northwest, and cluster II (three stands) was located in rather lower election (330-628 m) with aspects of north and northwest. The aspects of two clusters were not significantly different. Response-function analysis showed a significant positive response to March precipitation for both clusters. It indicates that moisture supply during early spring season is important to radial growth because the cambial growths of ring-porous species, such as Mongolian oak, start before leaf growth. Cluster II showed a positive response to the precipitation of middle and late growing season, too.

• Steel and Composite Structures
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• v.35 no.5
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• pp.635-640
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• 2020

The buckling analysis of the embedded sinusoidal piezoelectric beam is evaluated using numerical method. The smart beam is subjected to external voltage in the thickness direction. Elastic medium is simulated with two parameters of spring and shear. The structure is modelled by sinusoidal shear deformation theory (SSDT) and utilizing energy method, the final governing equations are derived on the basis of piezo-elasticity theory. In order to obtaining the buckling load, the differential quadrature method (DQM) is used. The obtained results are validated with other published works. The effects of beam length and thickness, elastic medium, boundary condition and external voltage are shown on the buckling load of the structure. Numerical results show that with enhancing the beam length, the buckling load is decreased. In addition, applying negative voltage, improves the buckling load of the smart beam.

• Journal of Environmental Impact Assessment
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• v.15 no.3
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• pp.207-215
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• 2006

The purpose of this paper is to analyze the spatial distribution and change of the frequency of Yellow Sand days and to examine their relationship with atmospheric circular characteristics at the surroundings of the Korean peninsula. Yellow Sand days data are used by intensity, Siberian High Index and monthly mean temperature of the Northern Hemisphere. In the Middle-western region, the occurrence frequency of Yellow Sand days was higher during the study period (1973-2004). Also, the occurrence frequency of Yellow Sand days increased to latter half 16 years compared with the first half 16 years, and be clearer in Middlewest regions. Yellow Sand days frequency increased, and the trend was distinct in the Jungbu region during the study period. Increasing trend of Yellow Sand days frequency was significant for the recent 22 years. Yellow Sand days had a negative relationship with Siberian High Index in February and March. Therefore, Siberian High Index became weaker in the spring, and possibility for the occurrence of Yellow Sand days was generating larger. Yellow Sand days had a positive relationship in monthly mean temperature of the Northern Hemisphere. Especially, the case of the strong Yellow Sand days is significant. Recently, global warming might be affecting the occurrence of strong Yellow Sand days.

• ALGAE
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• v.19 no.2
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• pp.129-137
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• 2004

Since cultural eutrophication has the detrimental effects on estuarine and coastal ecosystems, recognition of early stage of nutrient over-enrichment is critical for effective managements of the ecosystems. Since released nutrients into coastal ecosystems are diluted and dissipated through tidal action and rapid uptakes by marine plants, monitoring of in situ nutrient concentrations may not be useful for detecting early eutrophication on coastal and estuarine ecosystems. To develop an effective indicator of cultural eutrophication using marine plants, tissue N content and area normalized leaf mass of eelgrass, Zostera marina were examined in Kosung Bay and Koje Bay on the south coast of Korea from June 2001 to April 2003. Eelgrass tissue N content exhibited obvious seasonal variations. Leaf N content was highest during winter and early spring and lowest during summer. Eelgrass tissue N content was higher at Kosung Bay site, which has higher sediment organic content, than at Koje Bay site. Area normalized leaf mass showed reverse trend of leaf N content, and consequently, eelgrass leaf N content and leaf mass exhibited strong negative correlation at both study sites. The results of the present study suggested that the ratio of eelgrass leaf N content to area normalized leaf mass can be applied to assess environmental nitrogen conditions on the coastal and estuarine ecosystems.