• Korean Journal of Soil Science and Fertilizer
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• v.46 no.1
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• pp.16-22
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• 2013

Water is the most important resource for the maximum water use efficiency and yield of maize. Water has to be applied moderately based on the water requirement of maize. Crop water requirement (WR) is a function of the potential evapo-transpiration (PET) and crop coefficient (Kc). PET can be estimated by the climate data measured at the weather station in the production region. Kc was measured by the NIAST (RDA) through lysimeter experiments. In this study, the growth stage of maize was divided into five ones (G-1: Apr. 25 ~ May 20, G-2: May 21 ~ Jun. 20, G-3: Jun. 21 ~ Jul. 20, G4: Jul. 11 ~ Jul. 25, G5: Jul. 26 ~ Aug. 20). The average PET during maize growing season of the 45 areas was 2.85 mm $day^{-1}$. The highest water requirement was at the G-3 stage among the maize growth stages. The mean water requirement (MWR) according to growth stage was 1.74 ~ 2.42 (average 2.02), 2.99 ~ 4.21 (average 3.41), 3.82 ~ 5.25 (average 4.41), 3.05 ~ 4.31 (average 3.48), and 2.62 ~ 3.49 (average 3.01) mm $day^{-1}$ in the G-1, G-2, G-3, G-4 and G-5 stage, respectively. The total water requirement (TWR) according to growth stage was 45.37 ~ 63.04 (average 52.56), 92.54 ~ 130.59 (average 105.77), 76.46 ~ 105.09 (average 88.14), 45.73 ~ 64.67 (average 52.20), and 68.25 ~ 90.75 (average 78.33) mm in the G-1, G-2, G-3, G-4 and G-5 stage, respectively.

• Korean Journal of Weed Science
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• v.7 no.1
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• pp.52-57
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• 1987

To know the effects of weeding periods (weeding from 12 days, 28 days and 42 days after seeding to harvest, and weeding from seeding to 14 days, 28 days and 42 days after seeding) and growing conditions such as transparent polyethylene film mulch (P.E. mulch) and bare soil on growth and yield of peanuts, "Yeongho-Tangkong" was planted on May 10, 1984. Under P.E. mulch, the number of weeds was higher, but the weed dry weight was lower than in bare soil by the middle of July. Sixty days after seedings, the length of main stems in weedy check plots was longer, but shoot dry weight was lower compared to weed free plot. In the correlation coefficients between weed dry weight and the shoot dry weight of peanut on July 14, the growth retardation of peanuts due to weeds was showed earlier under P.E. mulch than in bare soil. Shoot dry weight, shelling ratio, number of seeds per pod, 100 pod weight, and seed yield were higher under P.E, mulch compared to bare soil. But weed dry weight, length of branches, number of pod bearing branches, number of pods per square meters, and pod yield were similar between P.E. mulch and bare soil. Shoot dry weight of peanuts, length of branches, number of pod bearing branches, number of pods per square meters, pod yield, 100 pod weight, 100 seed weight, and seed yield in weed free plots from 28 days after seeding to harvest (28 DAS-Harvest) were higher compared to weed free plots from 42 DAS-Harvest. However, in the weed free plot from seeding to 42 days after seeding seed yield was lower than that of the continuous weeding plot due to lower number of pod bearing branches and number of pods per square meters. When weed was not controlled at the later growth stages of peanuts, reduction in seed yield due to weeds was greater in bare soil than that under P.E. mulch.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.10
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• pp.905-915
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• 2010

With rising food waste, the management activities have gained growing attention, and the disposal options, particularly utilization of food waste for energy recovery, become central. This research examines the factors affecting food waste generation and the tendency to resource food waste. The self-administered questionnaire survey was conducted in newly built multifamily housing estates to collect data, and 300 responses were analyzed. The statistical analysis showed that most of the respondents purchased food materials in largely franchised grocery stores and discarded food that had been too long refrigerated to edible. The lifecycle of food consumption was divided into three states - food purchase plan, cooking and food waste collection. Regression analysis was employed to find out the relationships between three stages and food waste generation or tendency to resource food waste. The results described that food waste generation being affected by the stage of food purchase plan (food waste removal conditions) was statistically significant while it's statistically significant that the stage of cooking (prepurchase considerations) influenced the attitude toward food waste resource. The research findings indicated that food is overconsumed, and further many viewed food waste resources as a proactive and integrative mode in the global wave of sustainability.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.6
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• pp.614-620
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• 2002

The sea bass, Lateoiabrax japonicus is a highly valued fish in aquaculture in South Korea. For establishment of seedling production of sea bass,1 japonicus, we examined change of gonadal development and plasma steroid levels of sea bass reared in indoor tank. Male matured unsimultaneously faster than females and spawning of females took place between the end of January and March. After the spawning period, and until the following January, all the females were in preyitello genesis and in some males, spermatogenetic activity restarted gradually. In October, under reducing photoperiod, cortical alveoli appeared in growing oocyte and the development of spermatogenesis greatly increased. Between October and february, vitellogenesis and spermatogenesis occurred respectively in female and male and gonadosomatic index increased from 4.31 to $24.07\%$ in female and upper 6o/o in male. Also, two sex hormones were analyzed during the course of a reproductive cycle in the sea bass: plasma levels of the gonadal steroid testosterone (T) and estradiol-l7$\beta$ (E_{2}). Variation of the plasma concentrations of T and E, appeared to depend on gonad stages. Plasma T and E, levels were high from November to January, suggesting that an sufficient gonadal stimulation by both hormones may undergoing a processes for the formation of sperm and oocyte.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4560-4571
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• 2013

Current global issue of climate change is growing and greenhouse gases occur in most cities. To solve the problem of climate change, the city should be changed to low-carbon structure. Low-carbon city planning is a step-by-step plan from the initial establishment, from design and operation of urban structure, to maintenance and management should be considered as an integrated whole process. Under this background, this study evaluated the whole process of low-carbon urban planning ways. For this step, divided into three steps and eight divisions, 30 sub-indicators are derived. Through domestic and foreign cases analysis studies and survey of the relevant experts, results were derived. In order to improve these points, in the intial planning establishment stage, planning of urban policy and institutional steps should be made and the plan should be appropriate to the local characteristics. In the design and operation of urban structure stage, detailed and feasible approach is needed and maintenance and management stage, participation of various stakeholders, including establishing governance and management practices could see the need.

• Korean Journal of Microbiology
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• v.7 no.1
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• pp.10-21
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• 1969

The effect of glucose and 2-thiobarbituric acid on the biosynthesis of cell constituents such as protein, carbohydrate, DNA, RNA, phospholipid and PCA-soluble phosphate compounds in Chlorella duing the life cycle was measured, and the changes in the content of these main cellular components of the algal cell were analyzed in connection with the nuclear and cytoplasmic divison. In the normal autotrophic synchronous culture the contents of protein, RNA, and DNA in the cell showed a chracteristic changes according to the progress of cell development, increasing more or less throughout all the life cycle. The synthesis of protein is more prominent in the division period nad that of DNA is more active in the ripening period, while the synthesis of RNA is more rapid in the growing and ripening periods than other developmental stages. The period of division cycle was little affected by glucose in the medium, although the synchrony of the growth and cellular division was disturbed and the n value increased. The cotents of protein, carbohydrate, RNA nad DNA of the cell were increased by the glucose treatment throughout all the life cycle. On the other hand, both of cellular growth and division were retarded severely and the n value was decreased by the 2-thiobarbituric acid treatment throughout all the life cycle. On the other hand, both of cellular growth and division were retarded severely and the n value was decreased by the 2-thiobarbituric acid treatment. The synthesis of protein, carbohydrate, DNA, RNA and phospholipid of the cell was also retarded by 2-thiobarbituric acid. In the autotrophic, mixotrophic and 2-thiobarbituric acid-treated cultures, each having different mode cytoplasmic division, a common general schema occurring in the cell during the life cycle may be drawn as follows. The ratio of RNA to protein attains maximum value in the $L_1$-cell stage prior to the nuclear division and thereafter decreases during the periods of ripening and division. The ratio of PCA-soluble phosphate compounds to protein increased from the begining of the culture to $L_4$-cell stage successively and thereafter decreased gradually during the division period, while the ratio of protein to DNA kept almost constant up to the division period and thereafter increased during the division period. Therefore, it is presumed that the increase in the ratio of RNA to protein is to be an inducer of nuclear division and that the cytoplasmic division is induced by the increase in the ratio of protein to DNA.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.537-547
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• 2016

Deep Sea Water (DSW) has been exploited mainly by industry in a few countries including the U.S., Japan, Taiwan, and Korea. The development strategy of these states has pursued various goals based on their unique industrial environments and visions. Among them, Taiwan recently started their DSW industrialization, but has rapidly developed a variety of technologies and products. On the contrary, the Korean DSW industry has remained stagnant in the initial and growing stages for years, and now appears to need new plans and strategies for further development. The current literature lacks the strategy and policies required to foster the development of the domestic DSW industry. Relying upon the case of advanced foreign DSW industries, this study delineates the current status of the Korean DSW industry and discusses its future direction. Taiwan in particular has moved forward with policy development, financial and operation systems. This study attempts to provide a set of guidelines for the Korean DSW industry by focusing on the case of its Taiwanese equivalent. The Taiwanese strategical plans include premium drinkable water, government driven industrialization, diversification of DSW technologies and development of value-added products. This study provides a new direction for the DSW industry.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.659-663
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• 1999

Gametogenesis, reproductive cycle, condition factor, and meat weight rate of the surf clam, Tresus Keenae were studied by histological observations and morphometric data based on the samples which have been collected from the south coast of Korea, from January 1995 to February 1996. The annual ranges of the mean seawater temperature and specific gravity in habitat of the surf clam were $4.9\~24.9^{\circ}C$ and 1.0210$\~$1.0266, respectively. Monthly changes in the condition factor showed in a wide range from 0.2381 to 0.2827, began to increase in January and reached the first maximum (0.2827) in April. And then the value rapidly decreased in June, thereafter, reached the second peak (0.2812) in August. The condition factor of this species showed the two peaks, and gonadal development reached sexually mature and ripe conditions during the period of these two peaks. The meat weight rate ranged from $38.0\%$ to $46.4\%$, and its change showed a similar tendency with the condition factor. The reproductive cycle of this species can be divided into five successive stages: in both sex, multiplicative (December to January, July to August), growing (January to February, September to October), mature (February to April, September to November), spawning (April to June, September to November), and degenerative and resting stage (May to July, November to January).

• Journal of Digital Convergence
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• v.19 no.1
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• pp.29-43
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• 2021

Coinciding with the advent of COVID-19, online education is on the rise both domestically and globally, and has become an absolutely necessary and irreplaceable form of education. It is a very curious question what the perception of people about the suddenly growing form of education is, and how it has changed. This study investigated changes in consumers' perception of online education using big data. To this end, we divided the time into four stages: before COVID-19 (November to December 2019), after the triggering of COVID-19 (January to February 2020), right after the online classes started (March to April 2020), after experiencing some online education (May to June 2020). Then we conducted text mining, namely, keyword frequency analysis, network analysis, word cloud analysis, and sentiment analysis were performed. The implications derived as a result of the analysis can help education policy makers and educators working in the field to improve online education quality and establish its future directions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.836-844
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• 2020

In modern society, there is a growing demand for human tissue donation along with organ donation. However, the awareness of tissue donation and actual donation rates remain very low in South Korea. This study was undertaken to evaluate the current status of domestic laws and systems, and to compare them with the operation systems of major foreign countries, by reviewing literature and web sites of organ donation and registration. The authors present three measures to promote human tissue donation in Korea: integration of a dual legal system in a legal aspect, vitalization of the Opt-out system in terms of system operation, and activation of public relations in terms of social and cultural aspects. The Opt-out system, in particular, is the most effective way to activate transplants in the form of presumed consent of countries without undue pressure. However, the presumed consent method requires various stages of social public debate, and the requirement is a proper domestic understanding of the registration system for rejection. In conclusion, we believe the solution towards a positive inclination for organ donation is a public policy to increase the supply for organs and human tissue transplants, and positive perception of donations, public promotion, and support for postmortem donors and their families.