• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.415-417
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• 2002

Images of microcalcification specks showed large variation in conventional radiographs of phantoms which are approved for mammography image quality standard by the American College of Radiology (ACR). This kind of variation is not appropriate for image quality standards because the number of specks are visually counted in images and that number is important in image quality evaluation. Our study using synchrotron radiation (SR) imaging revealed the overlapping of micro-sized air bubble(s) to some specks, and also the structural deformation or crackings. Eight phantoms approved by ACR from two different makers and an air-bubble phantom were examined. SR imaging was performed at a synchrotron radiation facility, SPring-8, in Japan. The image-detector was a fluorescent-screen optical-lens coupling system using a CCD camera with a spatial resolution of 6 $\square$m. Objects when imaged with longer sample-to-detector distance show edge enhancement due to a difference in refraction indices, that is refraction enhancement. Refraction-enhanced SR images revealed that some of specks carried foreign objects, which were proven to be air. In phantoms provided by one maker, attaching/overlapping airs were observed for 62 out of 150 specks (41%) , with a higher incidence for the smallest specks. A speck becomes hardly visible in a conventional radiograph when air(s) overlaps the majority part of a speck, though depending on the size of the air-inclusion and on its configuration. Those airs might have been adsorbed on a speck surface before being embedded and then introduced into the matrix together with specks. Our study using SR imaging has clearly shown the nature of defects in some mammography phantoms which seriously degrade the quality as an image standard.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.1
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• pp.29-38
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• 2019

In order to investigate the behavioral characteristics of Pacific cod (Gadus macrocephalus) released at the entrance of Jinhae Bay, Korea, the direction and range of movement, swimming speed of the fish were measured with an acoustic telemetry techniques in winter, 2015. Three wild Pacific codes WC1 to WC3 (total length 66.0, 75.0, 76.0 cm; body weight 2.84, 2.79, 3.47 kg, respectively) were tagged with the acoustic transmitter. WC1 tagged with an acoustic transmitter internally by surgical method, WC2 and WC3, externally with the acoustic data logger and a micro data logger for recording audible sound waves including timer release unit. The movement routes of the tagged fish were measured more than five hours using VR100 receiver and a directional hydrophone. The directionality of the fish movement was tested by Rayleigh's z-Test, the statistical analysis, and a statistical program SPSS. Three tagged fishes were individually released on the sea surface around the entrance to the Jinhae Bay on 10 to 24 January 2015. WC1 moved about 13.32 km with average swimming speed of 0.63 m/s for six hours. The average swimming depth and water depth of the seabed on the route of WC1 were 7.2 and 32.9 m, respectively. The movement range of WC2 and WC3 were 7.95 and 11.06 km, approximately, with average swimming speed of 0.44 and 0.58 m/s for 5.1 and 5.3 hours, respectively. The average swimming depth of WC2 and WC3 were 18.7 and 5.0 m, and the water depth on the route, 34.4 and 29.8 m, respectively. Three fishes WC1 to WC3 were shown significant directionality in the movement (p < 0.05). Movement mean angles of WC1 to WC3 were 77.7, 76.3 and $88.1^{\circ}$, respectively. There was no significant correlation between the movement direction of fish (WC1 and WC2) and the tidal currents during the experimental period (p >= 0.05). Consequently, three tagged fishes were commonly moved toward outside of the entrance and headed for eastward of the Korean Peninsula, approximately, after release. It may estimate positively that the tidal current speed may affect to the swimming speed of the Pacific cod during the spring tide than the neap tide.

• Korean Journal of Environmental Biology
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• v.40 no.1
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• pp.54-69
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• 2022

We conducted a field survey from 2018 to 2020 to analyze the spatial distribution of phytoplankton communities at 13 stations in the East Sea. The diatom Chaetoceros curvisetus appeared as the dominant species in winter, and small flagellates less than 20 ㎛ prevailed in all seasons except winter. The seasonal average range of the micro (>20 ㎛), nano (20 ㎛≥Chl-a>3 ㎛), and picophytoplankton (≤3 ㎛) was 20.6-26.2%, 27.1-35.9%, and 40.8-49.0%, respectively. The composition ratio of nano and picophytoplankton was high at the surface mixed layer from spring to autumn when the water columns were strongly stratified. Especially, the stability of the water mass was increased when the summer surface water temperature was higher than that of the previous year. As a result, the nutrient inflow from the lower layer to the surface was reduced as the ocean stratification layer was strengthened. Therefore, the composition ratio of nano and picophytoplankton was the highest at 77.9% at the surface mixed layer. In conclusion, the structure of the phytoplankton community in the East Sea has been miniaturized, which is expected to form a complex microbial food web structure and lower the carbon transfer rate to the upper consumer stage.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.4
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• pp.333-341
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• 2008

Three embankments are located in the Chunggye Bay, each named as Changpo, Bokkil and Kuil and environmental changes are expected due to freshwater input. To investigate this phenomenon, three sample sites in front of each embankment gate were selected in Nov. 2006(autumn), Feb. 2007(winter), May. 2007(spring) and Aug. 2007(summer). At every point of embankment spot, large cells(micro-size, >$20\;{\mu}m$) of phytoplankton were turned out to be a major cause of algal bloom in Feb. 2007 and nano-size($2-20\;{\mu}m$) phytoplankton became dominant during rainy season. In rainy season, each point of embankment showed low salinity and transparency with higher ammonium and phosphorus concentrations than dry season. However, the number of phytoplankton has decreased and it is expected that freshwater influx has more influence on high turbidity and radical decrease of salinity than nutrient. According to the results of this study, therefore, nutrient could have more influence on growth of phytoplankton in dry season, but high turbidity and radical changes of salinity have more influence in rainy season.

• Journal of Korean Society of Forest Science
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• v.13 no.1
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• pp.1-24
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• 1971

In order to elucidate the feasibility to identify the plant species through the photographic tone this study was made. In this study the author made photographs of Juniperus chinensis L., and Populus glandulosa Uyeki, with the panchromatic film using either yellow filter or red filter in different seasons respectively. The author analyzed the value of tone variation at the level of stereoscopic view of the same photographs by using tone scale and Automatic Micro-Photo-Densitometer. The results obtained are summarized as follows: A. Tone scale reading 1. The tone of Populus glandulosa Uyeki was darker than that of Juniperus chinensis L. in a photograph. 2. Regardless of the tree species, tone of photographs obtained with yellow filter was darker than that with red filter. 3. Along the progresses of seasons, the photographic tone was changed. That is, from the spring to the summer it showed darker and than, from the summer to winter it changed lighter. 4. During winter and spring the discrimination between the both species of trees can be easily made by stereoscopic view whether there are leaves on the tree or not rather than by tone observation. 5. Regardless of tree species, variation of tone due to the age was noticed. The older trees have darker tone than the younger one. 6. It is recognized that the yearly difference depends on insolation quantities. 7. The highest reflex light-waves were in between $600m{\mu}$ and $660m{\mu}$ for both species of trees. B. Density reading 1. For the density reading, there was the same tendency as in tone scale reading. 2. The changes of peaks of the scanning curves with Populus glandulosa Uyeki is smoother and takes place in lower position than with Juniperus chinensis L. 3. The scanning curves on the 20th May was smoothest, and change of peaks increased gradually according to the season progresses. 4. In relation to the types of filter the photographs with yellow filter showed less changes of peaks then that with red filter.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.3
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• pp.63-75
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• 2015

As forest therapy is getting more attention than ever, it is important to organize time for activity and location based on spatio-temporal distribution of weather condition in forest. This study aimed to analyze precise spatio-temporal distribution of weather condition by installing long-term weather monitoring device in Yonghyun national natural recreation forest and using acquired weather data in order to support forest recreation and therapy activity. First, we statistically compared 4 models of semi-variogram and the results were all similar. We selected and analyzed the circular model for this study because it was presumed to be the best model for this case. We derived 128 results from the circular model and through semi-variogram, we identified seasonal and temporal distributions of temperature and humidity. Then, we used boxplot, made of partial sill level, to identify significant differences in seasonal and temporal distributions. As a result, in spring and early morning, both temperature and humidity showed equalized result. On the other hand, in summer and early afternoon, both temperature and humidity showed uneven result. In spring and early morning, changes in weather condition are shown little from spatial shifting, it is ideal to perform recreational activities and forest therapy but in summer and early afternoon, it is unadvisable to do so as the changes in weather condition could be harmful unless any other means of preparations are made. This study proposes its significance by analyzing seasonal micro-weather of single recreation forest and presenting seasonal and temporal outcomes.

• Horticultural Science & Technology
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• v.28 no.5
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• pp.836-844
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• 2010

This study was carried out to investigate plant characteristics and nutritional components of the genetically modified (GM) Chinese cabbage and its control line grown in the central and northern parts of Korea in order to establish the evaluating protocol and standard assessment. The GM and non-GM Chinese cabbage was planted with normal and concentrated density at two locations in spring and fall of 2008 and 2009. From the statistic analysis on plant characteristics and nutritional components, there were not many significant differences between GM and non-GM Chinese cabbage. Only few differences in the plant characteristics were found between the dense and normal planting. In the dense planting, there was no significant difference between GM and non-GM Chinese cabbages except for three out of 18 plant traits, such as leaf shape, hairiness and midrib length. On the other hand, nine plant traits including leaf length, leaf width, leaf color, leaf shape, fresh weigh of ground part, number of leaf, midrib length, midrib width and root diameter were slightly different between GM and non-GM Chinese cabbage in the normal planting. In case of leaf length, midrib length, midrib width and fresh weigh of ground part, there were significantly differences not only between two lines, but also between two locations. From nutritional component analysis, only five fatty acids were identified in the Chinese cabbage: palmitic acid, oleic acid, stearic acid, linoleic acid and linolenic acid. Except linoleic acid, four fatty acids in one gram of dried sample from GM line were little higher than those from non-GM line. However, there were no significant differences in total contents of fatty acids not only between GM and non-GM Chinese cabbage line, but also between northern and central cultivating areas in the normal and dense planting. According to the composition of inorganic elements identified in the samples from both lines, there were six macro-elements, such as N, P, Ca, K, Mg and Na, and four micro-elements, Cu, Fe, Mn and Zn. Based on the result from PCA analysis, specific clusters were not found between GM Chinese cabbage and the control line, but found between two regions.

• Korean Journal of Environment and Ecology
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• v.34 no.4
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• pp.294-303
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• 2020

This study aimed to examine was conducted to the ability of microclimate control in old pine forests by surveying pine forest in Buddhist temples, where the pine forest are stably growing through active protection in the Gyeongnam region, and comparing variation characteristics of microclimate characteristics (temperature and humidity) and distribution of vegetation type. The study sites were pine forests protected well by Buddhist temples (Haein-sa, Beomeo-sa, Tongdo-sa, and Bulguk-sa) in the southeast region of Korea and thus known for stably growing young pine trees. According to the vegetation distribution status analysis, these pine forests did not have a high ratio of pine trees. Except for Tongdo-sa, the ratio of deciduous forest and mixed (deciduous and pine trees) forest had a much larger presence than that of pine forest. Measured data of microclimate showed that the Tongdo-sa area had significantly different characteristics compared to the other three areas. Tongdo-sa area showed a significantly higher diurnal range of temperatures and humidity than the other three areas, in both spring and summer. It is due to the difference in vegetation management. The forests around Tongdo-sa are mostly pine forests, except for the developed areas, while those in the other three areas have a dominant ratio of deciduous brad-leaved forests. Intensive control of pine forest is not effective in mitigating microclimate, i.e., temperature and air humidity. Stress caused by rising temperatures and decreasing air humidity is blamed for the decline of pine forests. Thus, the current active management of pine forests, such as the Tongdo-sa case, has been found to have a greater negative impact on the temperature and humidity stress. Therefore, we believe that a new change in forest management is necessary to increase the effect of mitigating the microclimate of pine forests.

• Korean Journal of Environment and Ecology
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• v.28 no.6
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• pp.762-768
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• 2014

The purpose of this study is to analyze the soil $CO_2$ efflux and micro-climate of a preserved forest area located in a Mt. bulam urban nature park Quercus acutissima stand from June 2013 to May 2014. The research showed that the soil and heterotrophic $CO_2$ efflux were $28.14{\pm}7.99$ to $582.47{\pm}318.51$ and $12.32{\pm}8.04$ to $415.71{\pm}159.92mg\;CO_2{\cdot}m^{-2}{\cdot}h^{-1}$, respectively. In addition the seasonal soil $CO_2$ efflux of summer, autumn, winter, spring were 1169.1, 454.81, 72.08 and $494.23g\;CO_2{\cdot}m^{-2}{\cdot}month^{-1}$, respectively. On the other hand, the seasonal heterotrophic $CO_2$ efflux were 526.20, 340.09, 45.13 and $374.9g\;CO_2{\cdot}m^{-2}{\cdot}month^{-1}$, respectively. Moreover, the annual soil and heterotrophic $CO_2$ efflux was found to be 2190.22 and $1286.33g\;CO_2{\cdot}m^{-2}{\cdot}yr^{-1}$, respectively. The exponential function was also utilized for the regression analysis in order to correlate the environmental factors with the soil and heterotrophic $CO_2$ efflux. It was found out that both air and soil temperatures were positively correlated with the soil and heterotrophic $CO_2$ efflux. However, the amount of solar radiation and soil moisture has showed low correlation for both types of $CO_2$ efflux. Contribution of root $CO_2$ efflux to total soil $CO_2$ efflux in this Quercus acutissima stand was 33.60%.