• Korean Journal of Environmental Biology
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• v.19 no.1
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• pp.7-17
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• 2001

Growth optima and tolerance ranges of marine algae species nay vary greatly during the developmental stage. The establishment stage is clearly of great importance for each generation, affecting the performance of the adult population. The present study was aimed to determine the effect of various concentrations of inorganic nutrients and heavy metals on germination and germlings of Ulva pertusa Kjellman (Chlorophyta). Percent germination increased rapidly as irradiance level increased, reaching the maximum at 100 ${\mu}$mol m$\^$-2/s$\^$-1/ in both east and west seawater. Percent germination in the east seawater was higher than that in the west seawater at irradiances lower than 30 ${\mu}$mol m$\^$-2/s$\^$-1/, and there was no difference in percent germination between the two different seawaters at irradiances higher than 60 ${\mu}$mol m$\^$-2/s$\^$-1/. Germling growth increased in the both cases with increasing irradiances but no growth was found in the dark. Overall germling area was larger in the east seawater than in the west seawater. Number of cell increased with increasing irradiance and became light-saturated at 100 ${\mu}$mol m$\^$-2/s$\^$-1/ in the both cases. Germlings grown in the east seawater had more cells than those cultivated in the west seawater at irradiances lower than 60 ${\mu}$mol m$\^$-2/s$\^$-1/. In various combinations of nitrate and phosphate, percent germination increased with increasing nitrate concentrations irrespective of phosphate concentrations. At 3 days after inoculation, nitrate concentration of 2.5 ppm with all phosphate concentrations promoted germination. Area and number of cell of germlings increased with increasing nitrate concentrations in all phosphate concentrations. In various combinations of copper and lead, germination was delayed as copper concentrations increased in all lead concentrations. Percent germination was severely reduced at 1 ppm Cu$\^$2+/. Area and number of cell of germlings decreased with increasing copper concentrations in all lead concentrations. The highest copper concentration (1 ppm) clearly suppressed the germling growth in U. pertusa.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.50-60
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• 2008

We performed the experiment to evaluate the effect of different DO concentrations (0.5, 4.5 and 9.0 $mgO_2L^{-1}$) and water depths (20, 50 and 80 cm) on the filtering rate, mortality, and pseudifeces production of Unio douglasiae against the cyanobacterial bloom (mainly Microcystis aeruginosa). A solitary-living bivalve U. douglasiae was collected in the upstream region of the North Han River (Korea). The harvested mussels were carefully transferred to the laboratory artificial management system, which was controlled temperature $(18{\pm}2^{\circ}C)$, flow rate (10L $h^{-1}$), food $(Chlorella^{TM})$, sediment (pebble and clay), light intensity (ca. $20{\mu}mol$ photons), and photocycle (12 L : 12 D). In the field observation, the mussel mortality was significantly correlated with water temperature, pH and DO concentration (P<0.05). The mortality was decreased with water depth; 65, 90, 80% of mortality at 20, 50, 80 cm water-depth, respectively. Filtering rate (FR) showed the highest value at 50 cm water depth, and thereby the concentration of chlorophyll-${\alpha}$ decreased continuously by 94% of the control at the end of the experiment. In contrast, FR decreased by 34% of the initial concentration at 20 cm water depth. Over the given water-depth range, the mussel FR ranged from $0.15{\sim}0.20L\;gAFDW^{-1}hr^{-1}$ during the 18hrs of experiment, and thereafter, they appeared to be approximately 0.11, 0.26 and 0.30 L $gAFDW^{-1}hr^{-1}$ at 20, 50 and 80cm water depth, respectively. FR was highest with the value of 0.46L $gAFDW^{-1}hr^{-1}\;at\;0.5mgO_2 L^{-1}$ at the early stage of the experiment, while it increased with DO concentration. Maximum pseudofaeces production was 11.2 mg $gAFDW^{-1}hr^{-1}\;at\;9.0mgO_2L^{-1}$. Our results conclude that U. douglasiae has a potential to enhance water quality in eutrophic lake by removing dominant cyanobacteria, but their effects vary with environmental parameters and the water depth at which they are located.

• Economic and Environmental Geology
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• v.36 no.6
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• pp.441-455
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• 2003

The most common water types are found to be Ca-$HCO_3$, Ca-Na-$HCO_3$ and Ca-Na-$HCO_3$-Cl in Gwangju groundwater. Groundwater near the Gwangju stream are characterized Ca-Cl water type, with over 50 mg/L of C1- and 400 ${\mu}$S/cm of EC. The systematic variation of $Cl^-$, $HCO_3^-$,- EC and ${\gamma}^{18}O$ values in groundwater with distance away from drainages is caused by streamwater infiltration. Stable isotope data indicate that ${\gamma}$D and ${\gamma}^{18}O$ values of groundwaters near drainages were enriched by evaporation effect, showing a equation of ${\gamma}$D=7. 1${\times}{\gamma}^{18}O$-1. ${\gamma}^{18}O$ values over -6${\textperthansand}$ are anomalous in the unconfined groundwater zones, which are influenced by the local surface water enriched in $^{18}O$ composition. Groundwater in highland shows remarkably light ${\gamma}^{18}O$ values below -8$\textperthousand$. The infiltration of streamwater is dominant in unconfined alluvium aquifer near drainages. ${\gamma}^{13}$CDIC values (-17.6∼-15.2$\textperthousand$) of groundwaters near drainages revealed that dissolved inorganic carbon (DIC) is predominantly originated from natural soil-derived $CO_2$. ${\gamma}^{15}N$ and ${\gamma}^{18}O$ values of nitrate are 0∼17.0${\textperthansand}$ and 6.6∼17.4${\textperthansand}$, respectively. Relationship between ${\gamma}^{15}N$ and ${\gamma}^{18}O$ shows a systematic isotopic fractionation caused by denitrification of 40∼60%, suggesting that the major source of groundwater nitrate originated from nitrate of soils, and mixing nitrate of soil and sewage or manure.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.4
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• pp.317-326
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• 2019

Salinity which is often detected on reclaimed land is a major detrimental factor to crop growth. It would be advantageous to develop an approach for assessment of salinity and drought damages using a non-destructive method in a large landfills area. The objective of this study was to examine applicability of the decision tree classifier using imagery for classifying for spring potatoes (Solanum tuberosum) damaged by salinity or drought at vegetation growth stages. We focused on comparing the accuracies of OA (Overall accuracy) and KC (Kappa coefficient) between the simple reflectance and the band ratios minimizing the effect on the light unevenness. Spectral merging based on the commercial band width with full width at half maximum (FWHM) such as 10 nm, 25 nm, and 50 nm was also considered to invent the multispectral image sensor. In the case of the classification based on original simple reflectance with 5 nm of FWHM, the selected bands ranged from 3-13 bands with the accuracy of less than 66.7% of OA and 40.8% of KC in all FWHMs. The maximum values of OA and KC values were 78.7% and 57.7%, respectively, with 10 nm of FWHM to classify salinity and drought damages of spring potato. When the classifier was built based on the band ratios, the accuracy was more than 95% of OA and KC regardless of growth stages and FWHMs. If the multispectral image sensor is made with the six bands (the ratios of three bands) with 10 nm of FWHM, it is possible to classify the damaged spring potato by salinity or drought using the reflectance of images with 91.3% of OA and 85.0% of KC.

• Korean Journal of Food Science and Technology
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• v.35 no.5
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• pp.803-811
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• 2003

This study compared the physicochemical characteristics of yellow pigments in domestic and imported yellow croakers during distribution and storage. The croaker is generally adulterated by mixed color product of red and yellow pigment. This study found that the yellow pigment was stable during pH and temperature changes, but the red pigment was less stable than the yellow pigment. As for the light effect on the yellow pigment and the red pigment, there was no change in the remaining rate of the pigment stored in a dark place. The moisture content decreased according to the storage period, and the width of changes was large in the order of croaker stored at $5^{\circ}C$, croaker stored at $15^{\circ}C$ and dried croakers. The yellowness value of the abdomen of the adulterated white croaker did not show any large difference at the initial stage and for a storage period of 10 days at $5^{\circ}C$. However, the yellow croakers showed a decreasing trend according to the storage period at $15^{\circ}C$. The croaker can be generally adulterated by a mixed color of red and yellow pigment. For the texture change in accordance with the storage condition of the croakers, both the yellow and white croakers showed a gradually increasing trend of hardness when stored at $5^{\circ}C$ and $15^{\circ}C$.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.1
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• pp.87-103
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• 1999

Purpose: This study was undertaken to quantitatively estimate the degree of the damage and recovery of the irradiated rat condylar cartilage using the Image Analyzer. Materials and Methods: Experimental animals were 16 male rats of the Sprague-Dawley strain at the age of 20 day irradiated with the dose of 10 Gy in their head and neck region. Four rats were sacrificed at the each of the following time intervals - 1, 4, 7 and 14 days, respectively. The same number of control group animals were sacrificed at the each age of 21. 24, 27 and 34 days, respectively. The specimens were stained with 0.5％ toluidine blue and examined with light microscope. The condylar cartilage was divided into 4 zones; fibrous zone, proliferating zone, upper hypertrophic zone, and lower hypertrophic zone. And then, the proliferating zone was subdivided into 2 layers - upper and lower layer, and upper and lower hypertrophic zone were subdivided into three layers, respectively - upper, middle and lower layer. With the aid of Image Analyzer, morphometric analysis was performed. The thickness, the numerical density of cells, the cell area density, the extracellular matrix area density, the mean area of single cell, the mean area of extracellular matrix per single cell were measured and analysed. Results: In the experimental group, the thickness of the fibrous zone was slightly increased and that of the proliferating zone and the upper and the lower hypertrophic zone was markedly decreased. With time, the thickness of the fibrous zone was gradually increased and that of the proliferating zone and the upper and the lower hypertrophic zone was steadily in the decreased state. The numerical density of cells of the proliferating zone was increased on post-irradiated 1 day, but decreased after post-irradiated 4 day, and that of the upper hypertrophic zone was decreased. The numerical density of cells of the lower hypertrophic zone was decreased in the early stage and then was decreased or not significantly different from that of the control group with time. In the experimental group, the cell area density of the fibrous zone and the proliferating zone was decreased in the early stage and then gradually increased or not significantly different from that of the control group with time. The cell area density of the upper and the lower hypertrophic zone was varied with time. The extracellular matrix area density value were totally opposite to the cell area density values: The mean area of single cell of the fibrous zone and the proliferating zone was .decreased on post-irradiated 1 day, and increased after post-irradiated 4 day. The mean area of single cell of the upper hypertrophic zone was varied with each layer and time. In the experimental group, the mean area of extracellular matrix per single cell of the fibrous zone was not significantly different with control group, and that of the proliferating zone was decreased on post-irradiated 1 day, and increased after post-irradiated 4 day. The mean area of extracellular matrix per single cell of the lower hypertrophic zone was increased in the early stage. and that of upper hypertrophic zone was varied with each layer and time. Conclusion: The condylar cartilages of rats were affected by irradiation, but the changes were vaned with each layer and time. By morphometric analysis. the changes of the cells of the condylar cartilage of irradiated rat could be calculated quantitatively.

• Korean journal of communication and information
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• v.57
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• pp.33-48
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• 2012

Over the last decades, the issue of work or labor has played a critical role in prevailing discourses to represent the changed economic reality. Aesthetic labor, cultural work, network labor, team-work and alike, have played a dazzling role to represent the emerging economic order, employing the word of labor. Certainly, it is not less than a part of a wide range of shifts in order to make capital work with more effect by making up a workable and governable subject. In this article, I try to examine shifts around the media work which has contributed to expand the new discourse of 'labor.' I will say that it is quite crucial for accounting for the reality of media work to shed light on moves to represent media work, and, among others, one to transform the subjectivity involved in it among others. Furthermore, it would be necessary to take a close look at the subjectivity of media work and its modification to deal with and eliminate the precariousness of media work. Saying about media work without paying any attention to heterogenous and various practices to compose a media work, one is forced to regard media work as the matter of economic and legal interests. In addition, it would bring about that the cultural political concerns of media work will be detached from critical sight of the media cultural studies. Referring to major studies around media work in critical media studies, cultural studies and political economy of communication, this article will briefly look into the arrangement of contentions around subjectivity of media work in South Korea. And it will try to suggest what cultural-political strategy we need to investigate, fighting against the hegemonic power to generate and regulate media work and its workers in precarious conditions. It does not intend to search the media work and its complicated realities in detail in South Korea. I wish that it would make a preliminary step to propose and elaborate the critical analysis of media work and its form of subjectivities.

• Journal of the Korean Wood Science and Technology
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• v.43 no.1
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• pp.122-134
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• 2015

This study was conducted to investigate the potential of torrefied larch wood as a raw material of pellets. First of all, larch chip was torrefied at the temperatures of 230, 250 and $270^{\circ}C$ for 30, 50 and 70 min. Secondly, moisture content, moisture absorption, higher heating value and ash content of the torrefied chip were measured to examine the effects of torrefaction conditions on the fuel characteristics of larch. Thirdly, surfaces of the torrefied chip were observed by light microscope (LM), field emission scanning microscope (FE-SEM) and SEM-energy dispersive spectroscopy (EDXS). With the increases of torrefied temperature and time, contents of lignin increased and those of hemicellulose reduced. Moisture content of torrefied larch chip was greatly lower than that of non-torrefied chip. Moisture absorption of the torrefied chip decreased as torrefaction temperature increased. As torrefaction temperature increased, higher heating value and ash content of larch chip increased. However, durability of torrefied-larch pellets was remarkably lower comparing to non-torrefied-larch pellets. When surface of larch chip was observed by LM and FE-SEM, surface color and cell wall of the chip was getting darker and more collapsed with the increases of torrefaction conditions. Through the analysis of SEM-EDXS, distribution and quantity of lignin existing on the surface of larch chip increased with the increases of torrefied conditions. In conclusion, $270^{\circ}C$/50 min might be an optimal condition for the torrefaction of larch with the aspect of fuel characteristics, but torrefaction condition of $230^{\circ}C$/30 min should be considered according to the durability of torrefied-larch pellets.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.2
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• pp.295-305
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• 2002

This paper, in which whose subjects were 43 cerebrovascular accident patients analysed the effects of flood habits and attitudes on the nutrient intake. In respect to energy intake, the subjects took 106% of RDA. The protein intake was on the average of 119.1 g, which was 187% of RDA. The fat intake by the subjects on the whole was 60.5 g. The fiber intake of the subjects was 9.6 g. Those who like sweets took in significantly less energy and carbohydrate and more fat than those who didn't like sweets. Those who liked salty flood took in 7890 mg of sodium while those who didn't like salty food took in 5579 mg of sodium. The former took in significantly more sodium than the latter (p < 0.05). The examination of the amount of nutrient intake in terms of meal pattern, showed that those who had two meals a day were significantly higher in the level of weight and BMI was significantly higher (p<0.05) and the level of energy, protein, calcium, iron, vitamin A, vitamin C and cholesterol was significantly higher. Those who thought they had heavy meals took significantly more energy, protein, calcium iron, vitamin A vitamin B$_1$and vitamin C than those who thought they had light meals. Rapid eaters took more nutrients than slow eaters. The multiple regression analysis has shown that the effect of the independent variables on the energy intake are in the order of eating speed, eating volume and eating frequency. They can explain 24.6% of the energy intake. As a result, the faster is eating speed, the heavier is eating volume, and the lower is eating frequency, the higher is the energy intake (p <0.01).

• Journal of agricultural medicine and community health
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• v.17 no.1
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• pp.34-45
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• 1992

In this county, the gap between the urban 'haves' and the rural 'have-nots' continues to be an increasing problem. WHO and UNICEF see primary health care(PHC) as the key to achieving an acceptable level of health throughout the world as a community development. PHC is essential health care made accessible to individuals and families in the community by means acceptable to them. It is the first level of contact of individual, the family, and community with the national health system. It includes at least education on health system. It includes at least education on health problems, promotion of food supply, MCH including family planning, immunization against infectious diseases, control of endemic diseases, treatment of common diseases and injuries, promotion of mental health, and provision of essential drugs. However, of the aboves, education concerning of mental health problems and the methods to identify, prevent, and control them is the principal step of establishment. In Korea, the category of PHC worker includes the physician as public doctor and nurse as primary health care practitioner and community health leader as village health worker. PHC workers of the aboves will thus function best if they are appropriately trained to respond to the health needs of the community. However in this country, since the national PHC service project launched in 1980, the government has not developed and performed appropriate and enough education and training activities. In light of above reasons, several categories of health education activities had been planned and performed being aimed at above specific target groups and the main focus was on the village health workers for about one year from July 1991 to July 1992 in Yeoju Kun of Kyonki Province. At the end of the period, evaluation of education input was carried out to measure the improvement of healthful life of people in terms of awareness, attitude, and practice. At the end of the period, evaluation of education input was carried out to measure the improvement of healthful life of people in terms of awareness, attitude, and practice. The totals of 80 village health workers, 13 public health practitioners and 9 public docters took in the course of health education for a few hours at every month and the evaluation works of educational effect were taken. The results the study were as follows. 1) Number of persons who realized the maxim "health care of the people is a duty of the government" increased after the education course, On the other hand, the rate of satisfaction on the effort of government for health promotion of the people decreased. 2) Public doctors and primary health care practitioners(nurses) liked and enjoyed the education schedule as a meeting of peer group. It provided chances of communication with staffs of Korea University Hospital. It was said that lectures covered great deal of knowledge and technic they urgently needed in the field. 3) After finishing the education course, more of village health workers(VHW) thought they adapted themselves to their roles and functions showing increased number of home visit and contact with primary health care practitioners by month. 4) In case of patient refer, VHW preferred primary health care practitioners to public doctors. 5) Capability of VHWs in most of their functions increased dramatically after when the education course finished except tuberculosis control.