• Korean Journal of Food Science and Technology
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• v.38 no.2
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• pp.249-255
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• 2006

The optimum culture conditions for the ice nucleating activity and the cell growth of Xanthomonas translucens KCTC 2751 were investigated. The optimum initial pH and temperature for the cell growth and the ice nucleating activity were 6.5 and $25^{\circ}C$, respectively. The optimum culture medium for the ice nucleating activity was composed of 1.0% maltose, 1.4% yeast extract, 0.8% digested of gelatin, and 0.03% KCI in distilled water. Freezing operations carried out on distilled water showed that the degrees of supercooling were $-7.90^{\circ}C$ without ice nucleators, $-1.56^{\circ}C$ with silver iodide as a commercial ice nucleator, and $-1.36^{\circ}C$ when Xanthomonas translucens KCTC 2751 were added. During progressive freeze-concentration assays, the addition of Xanthomonas translucens KCTC 2751 led to lower saccharose concentrations in the crystals, while the cells led to higher saccharose concetrations in the concentrated phase.

• Journal of Biosystems Engineering
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• v.41 no.4
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• pp.328-336
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• 2016

Purpose: The heat culture areas of greenhouses have been continuously increasing. In the face of international oil price fluctuations, development of energy saving technologies is becoming essential. To save energy, auxiliary heat source and thermal insulation technologies are being developed, but they lack cost-efficiency. The present study was conducted to save energy by developing a conceptually new semi-basement type greenhouse. Methods: A semi-basement type greenhouse, was designed and constructed in the form of a three quarter greenhouse as a basic structure, which is an advantageous structure to inflow sunlight. To evaluate the performance of the developed greenhouse, a similar structured general greenhouse was installed as a control plot, and heating tests were conducted under the same crop growth conditions. Results: Although shadows appeared during the winter in the semi-basement type greenhouse due to the underground drop, the results of crop growth tests indicated that there were no differences in crop growth and development between the semi-basement type greenhouse and the control greenhouse, indicating that the shadows did not affect the crop up to the height of the crop growing point. The amount of fuel used for heating from January to March was almost the same between the two greenhouses for tests. The heating load coefficients of the experimental greenhouses were calculated as $3.1kcal/m^2{\cdot}^{\circ}C{\cdot}h$ for the semi-basement type greenhouse and $2.9kcal/m^2{\cdot}^{\circ}C{\cdot}h$ for the control greenhouse. Since the value is lower than the double layer PE (polyethylene) film greenhouse value of $3.5kcal/m^2{\cdot}^{\circ}C{\cdot}h$ from a previous study, Tthe semi-basement type greenhouse seemed to have energy saving effects. Conclusions: The semi-basement type greenhouse could be operated with the same fuel consumption as general greenhouses, even though its underground portion resulted in a larger volume, indicating positive effects on energy saving and space utilization. It was identified that the heat losses could be reduced by installing a thermal curtain of multi-layered materials for heat insulation inside the greenhouse for the cultivation of horticultural products by installing thermal curtain of multi-layered materials for heat insulation inside the greenhouse, it was identified that the heat losses could be reduced.

• Journal of agriculture & life science
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• v.46 no.1
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• pp.29-34
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• 2012

To examine possibilities to make use of woodceramics for the lower material of hot-floored ondol boards, woodceramics made from sawdust board with Pinus densiflora, put them in a wood frame and concrete block and heated them sending an electric current, and measured changes in surface temperature of a laminated floor board and a plywood floor board. As the sending an electric current to time passed, their surface temperature increased rapidly up to 20 minutes, and then gradually ascended. In terms of the surface temperature in the wood frame, the beginning temperature of a plywood floor board was higher than that of laminated floor one; however, as time passed, a laminated floor board's temperature rose, and after 60 minutes, it showed similar to the temperature of a floor board of lamination. On the other hand, the surface temperature in a concrete block showed that the laminated floor board was higher than the plywood floor board in both early and 60-minute later temperatures. With the lapse of time after switching off, the surface temperature of floor boards slowly dwindled up to 9 minutes, and from that time on, began to drop sharply. In terms of the descent speed of surface temperature, when woodceramics' surface temperature was adjusted at $70^{\circ}C$, the laminated floor board was the highest; when it was at $80^{\circ}C$, the plywood floor board was the highest, resulting in rapid descent speed of heat.

• Journal of agriculture & life science
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• v.43 no.1
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• pp.35-41
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• 2009

This study was conducted to analyze the phenotypic trends and environmental factors affecting the following carcass traits : slaughter weight, backfat thickness and carcass grade, in 1,251,572 commercial pigs for 7 years from 1999 to 2005. The average slaughter weight of female, male and barrow were $82.97{\pm}0.008$ $82.00{\pm}0.090$ and $82.79{\pm}0.008$, respectively. The average backfat thickness of female, male and barrow were $19.27{\pm}0.006$, $15.99{\pm}0.072$ and $22.49{\pm}0.006mm$, respectively. The slaughter weight tended to increase over the slaughter years, for backfat thickness remained, even though a significant drop of backfat thickness on 2002($18.75{\pm}0.027$). The slaughter weight was significantly higher in winter($83.29{\pm}0.032$), while the backfat thickness was significantly lower in summer($19.10{\pm}0.026$). The carcass grade A increased from 2000 to 2003, but decreased slightly after 2003. On the contrary, the carcass grade B decreased from 2000 to 2003, but increased slightly after 2003.

• Korean Journal of Remote Sensing
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• v.37 no.6_1
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• pp.1669-1683
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• 2021

AI intelligent agriculture and digital agriculture are important for the science of agriculture. Leaf chlorophyll contents(LCC) are one of the most important indicators to determine the growth status of vegetable crops. In this study, a support vector machine (SVM) regression model was produced using an unmanned aerial vehicle-based RGB camera and a multispectral (MSP) sensor for onions and garlic, and the LCC estimation applicability of the RGB camera was reviewed by comparing it with the MSP sensor. As a result of this study, the RGB-based LCC model showed lower results than the MSP-based LCC model with an average R² of 0.09, RMSE 18.66, and nRMSE 3.46%. However, the difference in accuracy between the two sensors was not large, and the accuracy did not drop significantly when compared with previous studies using various sensors and algorithms. In addition, the RGB-based LCC model reflects the field LCC trend well when compared with the actual measured value, but it tends to be underestimated at high chlorophyll concentrations. It was possible to confirm the applicability of the LCC estimation with RGB considering the economic feasibility and versatility of the RGB camera. The results obtained from this study are expected to be usefully utilized in digital agriculture as AI intelligent agriculture technology that applies artificial intelligence and big data convergence technology.

• Journal of Environmental Impact Assessment
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• v.28 no.3
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• pp.245-262
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• 2019

The objectives of this study were to construct a three-dimensional water quality model (EFDC) for the river reach between Chilgok Weir and Gangjeong-Goryong Weir (GGW) located in Nakdong River, and evaluate the effect of hydraulic changes, such as water level and flow velocity, on the control of water quality and algae biomass. After calibration, the model accurately simulated the temporal changes of the upper and lower water temperatures that collected every 10 minutes, and appropriately reproduced changes in organic matter, nitrogen, phosphorus, and cyanobacteria. However, the simulated values were overestimated for the diatoms and green algae cell density, possibly due to the uncertainties of the parameters associated with algae metabolism and the lack of zooplankton predation function in the simulations. As a result of scenario simulation of running the water level of GGW from EL. 19.44 m to EL. 14.90 m (4.54 m drop), Chl-a and algae cell density decreased significantly.In particular,the cyanobacteria on the surface layer, which causes algal bloom, declined by 56.1% in the low water level scenario compared to the existing management level. The results of this study are in agreement with the previous studies that maintenance of critical flow velocity is effective for controlling cyanobacteria, and imply that hydraulic control such as decrease of water level and residence time in GGW is an alternative to limit the overgrowth of algae.

• Korean Journal of Heritage: History & Science
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• v.48 no.1
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• pp.80-95
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• 2015

The purpose of this study was to reduce the drop out rates and enhance the quality of docent training education program in the Nature Heritage Center by providing educational services appropriate to the docents' needs based on the docents satisfaction survey. In this research, we conducted the survey to analyze the importance-satisfaction of natural heritage docent satisfaction in natural heritage docent training programs. The subjects of this survey were 30 docent in Natural Heritage Center. To develop a questionnaire, a factor analysis was conducted, as a result, 6 factors and 22 questions were presented. They are 'curriculum and instruction', 'advice for docent', 'educational environments', 'administrative services', 'support for docents', 'docent life'. The results of t-test, there was a significant difference between importance and satisfaction of the every 22 questions, the mean score of satisfaction(M=3.87, SD=.08) was lower than that of importance(M=4.10, SD=.20). According to ISA, the items located in "concentrate here" were deduced. They are 3 items from administrative services, device for docent, curriculum and instructions. To put in concretely, They were 'lecture content(subject)', 'teaching method', 'service attitude of personnel', 'interest in a docent' Based on these results and descriptive responses from the docents, the strategies for docent satisfaction in natural heritage docents training programs were suggested.

• Journal of Industrial Convergence
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• v.19 no.1
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• pp.117-127
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• 2021

The purpose of this study was to identify the relationship between social support, academic self-efficacy, and learning agility on intention of academic dropout among nursing students. Data collection was conducted online surveys from November 9 to 27, 2020. The 363 students were conveniently sampled from the school of nursing in K-do in Korea. The contents of the self-reported questionnaire included social support, academic self-efficacy, learning agility, intention of academic dropout. As a result, The score of each variables were like this: social support 4.32, academic self-efficacy 3.66, learning agility 3.40, intention of academic dropout 2.08. The factors that affecting intention of academic dropout among nursing students are academic self-efficacy, learning agility, satisfaction on major, perceived mental health status, grade in score and grade, which explained 30.4% of the variances. Therefore in order to lower the intention of dropping out of nursing students, it is considered that the development of programs considering individual characteristics and systematic support are necessary.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.6
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• pp.163-179
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• 2020

With the expansion of platform-based taxi service, mobility and convenience of users are getting better. However, due to profitability problem, marginalized areas in the supply of the service are expected to appear. As such, this study analyzed spatial marginalization of taxi service caused by imbalance in supply and demand during the night-time when public transportation service is suspended. According to hot-spot analysis of taxi, outskirt of a city and residential areas showed high vacancy and greater number of drop-offs compared to the number of pick-ups. On the contrary, they were confirmed low in the center and sub-centers of a city. Centrality analysis also showed a similar pattern with hot-spot analysis. Due to this, drivers may refuse to pick up a customer bound for an area with lower out-degree centrality compared to in-degree centrality as it might be difficult for the drivers to pick up another customer after dropping off the current customer. Thus, customers may need to wait for a taxi for a longer time. For this reason, improvement in spatial marginalization caused by mismatch of supply and demand is required. Also, the outcome of this study is expected to be utilized as a basic data.

• KDI Journal of Economic Policy
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• v.45 no.4
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• pp.57-77
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• 2023

The Chonsei component holds the highest level of weight (5.4%) in the composition of the Korean consumer price index (CPI). The variations in Chonsei prices are directly reflected in the CPI as a representation of cost swings. The Chonsei refers to a deposit that accumulates the costs related to housing services and is mostly affected by variations in rental rates. Nevertheless, it is important to note that Chonsei prices are also susceptible to fluctuations in interest rates, regardless of the rent prices. Therefore, if Chonsei were directly and one-to-one indexed to the CPI, they could include changes other than residential service prices. After analyzing the time series data of the Chonsei index and rent index inside the CPI, it becomes apparent that the Chonsei index displays an average annual growth rate of 2.3%, whilst the rent index reveals a growth rate of 0.9%. The observed disparity in growth rates indicates a divergence in trends between the two indices. It is posited that the Chonsei index, when capitalized, has had a more rapid increase compared to the rental index, owing to the gradual drop in interest rates. To effectively reflect fluctuations in the housing service costs, proxies for the Chonsei index were utilized in the construction of a consumer price index. The findings of our study suggest that, overall, the newly developed CPI demonstrates a comparatively lower rate of inflation when compared to the official CPI. Furthermore, the inclusion of imputed rents for owner-occupied housing in CPI amplifies this effect.