• Korean Journal of Soil Science and Fertilizer
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• v.48 no.4
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• pp.240-245
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• 2015

The monitoring of soil fertility changes in orchard is very important for agricultural sustainability. Field monitoring was performed to evaluate the soil chemical properties of 140 orchard (23 sites for sandy loam, 88 sites for loam, 28 sites for silt loam, and 1 site for loamy fine sand) in Gyeongnam province every 4 years from 2002 to 2014. Soil chemical properties such as pH, electrical conductivity, amount of organic matter (OM), available phosphate ($P_2O_5$), lime requirement (LR), exchangeable potassium (K), calcium (Ca), magnesium (Mg), and sodium were analyzed. The amount of OM, exchangeable K, Ca, and Mg were significantly increased as cultivation year increases. The frequency distribution within optimum range of subsoil chemical properties in 2014 was 34.3% for pH, 35.0% for OM, 17.1% for available $P_2O_5$, 22.9% for exchangeable K, 15.7% for exchangeable Ca, and 22.1% for exchangeable Mg. In addition, the available $P_2O_5$ and exchangeable calcium were excess level with portions of 69.3% and 48.6%, respectively. The soil chemical properties in the topsoil and subsoil showed that soil pH was significantly higher in sandy loam soil than those from the loam and silt loam soils. The OM, exchangeable K, Mg, and LR of loam soil were higher than those from the sandy loam soil. These results indicated that a balanced management of soil chemical properties as affected by soil texture can improve the amount of fertilizer applied for sustainable agriculture in orchard field.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.5
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• pp.675-682
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• 2021

Fire accidents on land and at sea can cause serious casualties; specifically, owing to the nature of marine plants and ships, the mortality rate at sea from suffocation in confined spaces is significantly higher than that on land. To prevent such cases of asphyxiation, it is essential to install ventilation fans that can outwardly direct these toxic gases from fires; however, considering the scale of marine fires, the installation of large ventilation fans is not easy owing to the nature of marine structures. Therefore, in this study, we developed a new concept for fire safety technology to control toxic gases generated by fires from applied direct current (DC) electric fields. In the event of a fire, most flames contain large numbers of positive and negative charges from chemi-ionization, which generates an "ionic wind" by Lorentz forces through the applied electric fields. Using these ionic winds, an experimental study was performed to artificially control the fire smoke caused by burning paper and styrofoam, which are commonly used as insulation materials in general buildings and ships. The experiments showed that a fire smoke could be artificially controlled by applying a DC voltage in excess of ±5 kV and that relatively effective control was possible by applying a negative voltage rather than a positive voltage.

• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.3
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• pp.41-57
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• 2021

This study evaluated the application of water quality management measures using the SWAT model and the effectiveness of the measures using the load duration curve targeting the Seohwacheon watershed located upstream of Daecheongho. As water quality management measures, artificial wetlands, reduction of neglected livestock, reduction of runoff from greenhouses, restoration of ecological rivers, application of LID technology, and management of point sources were applied. The applied technology evaluated the efficiency of water quality improvement measures by using the target water quality excess rate and the degree of load reduction for each sulfur through the load duration curve. The load duration curve was created by creating a long-term flow duration curve using SWAT and multiplying it by the target water quality. For the target water quality, the value corresponding to the 60th percentile was set as the target water quality using the 10-year data from the Okcheoncheon water quality observation point located in the downstream of Seohwacheon. Through this study, it was possible to confirm the applicability of various water quality measures through the SWAT model, and to examine the applicability of each period according to the sulfur through the load retention curve.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.3
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• pp.5-16
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• 2021

In this study, the applicability of the MBR(Membrane Bio Reactor) process of oxygen dissolve was evaluated through comparison and evaluation of the efficiency of oxygen dissolve device and conventional aeration device in the explosive tank within the MBR process. The organic matter and ammonia oxidation by oxygen dissolve device were evaluated, and the efficiency of persaturation was evaluated by applying real waste water (anaerobic digester effluent treatement from food waste). SCOD and ammonia removal rates for oxygen dissolve device and conventional aeration device methods were similar. However, it was determined that the excess sludge treatment cost could be reduced as the yield of microorganisms by oxygen dissolve device is about 0.03 g MLSS-produced/g SCOD-removed lower than that of microorganisms by conventional aeration device. The removal rates of high concentrations of organic matter (4,000 mg/L) and ammonia (1,400 mg/L) in anaerobic digester effluent treatment from food waste were compared to the conventional aeration device and the oxygen dissolve device organic matter removal rate was approximately 13% higher than that of the conventional aeration device. In addition, for MLSS, the conventional aeration device was 0.3 times higher than for oxygen dissolve device. This is believed to be due to the high progress of sludge autooxidation because the dissolved oxygen is sufficiently maintained and supplied in the explosive tank for oxygen dissolve device. Therefore, it was determined that the use of oxygen dissolve device will be more economical than conventional aeration device as a way to treat wastewater containing high concentrations of organic matter.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.114-126
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• 2021

This paper compared bridge maintenance in United Stated, United Kingdom, Japan, and Korea. Bridges play an essential role in transportation network and in the economic production process. To provide a desirable level of service to the public within limited budgets, it is required to provide effective bridge maintenance activities (e.g. inspection and repair/rehabilitation) at acceptable level of bridge service. A number of bridges are expected to age rapidly in Korea, which will be the excess burden of government. Since several countries have experienced a number of deteriorated bridges because of aging, the countries aforementioned in this study have already developed comprehensive bridge maintenance programs such as inspection practice and repair/rehabilitation techniques. Therefore, the goal of this paper is to synthesize and to compare useful knowledge on bridge maintenance and bridge crack repair/restoration of deteriorated concrete bridge in the four countries. Finally, recommendations that will serve as guidance to transportation agencies for potential enhancements to bridge maintenance and bridge repairs are presented.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.201-206
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• 2019

This report constitutes the first demonstration in Korea of single-crystal lateral gallium oxide ($Ga_2O_3$) as a metal-oxide-semiconductor field-effect-transistor (MOSFET), with a breakdown voltage in excess of 480 V. A Si-doped channel layer was grown on a Fe-doped semi-insulating ${\beta}-Ga_2O_3$ (010) substrate by molecular beam epitaxy. The single-crystal substrate was grown by the edge-defined film-fed growth method and wafered to a size of $10{\times}15mm^2$. Although we fabricated several types of power devices using the same process, we only report the characterization of a finger-type MOSFET with a gate length ($L_g$) of $2{\mu}m$ and a gate-drain spacing ($L_{gd}$) of $5{\mu}m$. The MOSFET showed a favorable drain current modulation according to the gate voltage swing. A complete drain current pinch-off feature was also obtained for $V_{gs}<-6V$, and the three-terminal off-state breakdown voltage was over 482 V in a $L_{gd}=5{\mu}m$ device measured in Fluorinert ambient at $V_{gs}=-10V$. A low drain leakage current of 4.7 nA at the off-state led to a high on/off drain current ratio of approximately $5.3{\times}10^5$. These device characteristics indicate the promising potential of $Ga_2O_3$-based electrical devices for next-generation high-power device applications, such as electrical autonomous vehicles, railroads, photovoltaics, renewable energy, and industry.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.406-414
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• 2018

The objective of this study was to analyze the effect of characteristics of maritime telemedicine (service quality, recognition or not of service, health counselling service experience or not) on seafarer's satisfaction, and also analyze the effect of seafarer's satisfaction on loyalty. This study's data was collected from the Research Report of Survey of telemedicine service subjects in 2017 conducted in the maritime telemedicine pilot project. However, only 103 seafarers who received maritime telemedicine (Tele-Monitering) services were analyzed statistically. The main results of this study were as follows. ⅰ) Better service quality led to higher levels of satisfaction, ii) High levels of seafarer's satisfaction led to high levels of loyalty, iii) Seafarers whose age is under 50 than 30 years old are less satisfied, ⅳ) In total boarding career, Seafarers with more than 5 years but less than 10 years were more satisfied than seafarers with less than 5 years, ⅴ) Seafarers with more than 10 years but less than 15 years were more satisfied than seafarers with less than 5 years, ⅵ) Seafarers with more than 15 years but less than 20 years were more satisfied than seafarers with less than 5 years, ⅶ) Also, Seafarers in excess of 20 years were more satisfied than seafarers with less than 5 years, In conclusion, ⅰ) Better service quality led to higher levels of satisfaction and loyalty. Accordingly, the improvement of service quality is not only an important factor in improving satisfaction and loyalty, but also plays an important role in forming a positive image of maritime telemedicine. ⅱ) Seafarers with younger age and lower overall total boarding career were more satisfied. It is believed that the seafarer who are willing to use telemedicine and who are willing to refer to others are young.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.9
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• pp.1397-1406
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• 2019

Objective: Feed energy required for pigs is first prioritized to meet maintenance costs. Additional energy intake in excess of the energy requirement for maintenance is retained as protein and fat in the body, leading to weight gain. The objective of this study was to estimate the metabolizable energy requirements for maintenance ($ME_m$) by regressing body weight (BW) gain against metabolizable energy intake (MEI) in growing pigs. Methods: Thirty-six growing pigs ($26.3{\pm}1.7kg$) were allotted to 1 of 6 treatments with 6 replicates per treatment in a randomized complete block design. Treatments were 6 feeding levels which were calculated as 50%, 60%, 70%, 80%, 90%, or 100% of the estimated ad libitum MEI ($2,400kJ/kg\;BW^{0.60}\;d$). All pigs were individually housed in metabolism crates for 30 d and weighed every 5 d. Moreover, each pig from each treatment was placed in the open-circuit respiration chambers to measure heat production (HP) and energy retained as protein ($RE_p$) and fat ($RE_f$) every 5 d. Serum biochemical parameters of pigs were analyzed at the end of the experiment. Results: The average daily gain (ADG) and HP as well as the $RE_p$ and $RE_f$ linearly increased with increasing feed intake (p<0.010). ${\beta}$-hydroxybutyrate concentration of serum tended to increase with increasing feed intake (p = 0.080). The regression equations of MEI on ADG were MEI, $kJ/kg\;BW^{0.60}\;d=1.88{\times}ADG$, g/d+782 ($R^2=0.86$) and $ME_m$ was estimated at $782kJ/kg\;BW^{0.60}\;d$. Protein retention of growing pigs would be positive while REf would be negative at this feeding level via regression equations of $RE_p$ and $RE_f$ on MEI. Conclusion: The $ME_m$ was estimated at $782kJ/kg\;BW^{0.60}\;d$ in current experiment. Furthermore, growing pigs will deposit protein and oxidize fat if provided feed at the estimated maintenance level.

• Journal of Wetlands Research
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• v.21 no.3
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• pp.244-250
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• 2019

Due to the industrial development and population growth, it has recently been shown that there are many problems caused by the rinked treatment water in local goverments and sewage treatment plants. The rinked treatment water has a characteristic of low flow rate and high concentration unlike general sewage. These characteristics increase sewage treatment difficulty and sewage treatment fee of sewage treatment facilities. Among the many influencing factors that increase sewage treatment unit cost, 'linked treatment load/design inflow load (%)' was derived as the most correlated factor. Through the selection and modeling of sewage treatment plants, the excess scope of design discharge water quality was investigated under the conditions of temperature and the conditions of 'linked treatment load/design inflow load (%)' taking into account the effects of the four seasons. The study found that for TN, 'linked treatment load/design inflow load (%)' was 19.7%, 22.6%, 25.1%and 27.7%, respectively, under conditions of $5^{\circ}C$, $10^{\circ}C$, $20^{\circ}C$ and $25^{\circ}C$. In case of TP, 'rinked treatment load/design inflow load (%)' was 10.7%, 12.2%, 15.6% and 17.5% at $5^{\circ}C$, $10^{\circ}C$, $20^{\circ}C$, and $25^{\circ}C$, respectively, under conditions of $5^{\circ}C$, $10^{\circ}C$, $20^{\circ}C$ and $25^{\circ}C$.

• The Journal of the Korea Contents Association
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• v.19 no.9
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• pp.122-134
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• 2019

This study aims to conceptualize characteristics of the Korean traditional dance, and to categorize and analyze the recognition of experience of passing down education of Seungmu(Buddhist Dance), Salpurichum(Exorcism Dance) and Taepyeongmu(Dance of Peace). Dividing into groups of two: an experienced person twenty years or more in the Korean dance and a person who completed the traditional dance three years or more, three groups were selected. We connected the characteristics of the traditional dance experienced in passing down education with the recognition experience in the training courses. Categorizing thematically the process and the recognition of experience in the passing down education program, we attempted mutual group discussion and inductive area analysis on the basis of in-depth interview, tutorial discussion and analysis contents. As a result of this study, first, the characteristics of the Korean traditional dance that graduates of the program by repertory empathize were the experience of the sinmyung(the excess of mirth) and improvisation, the supreme self-controlling beauty and the best beauty of expression. Second, the recognition of experience in the passing down education program runs as follows: Interacting in the centre of the process, new education system for transmission, and formation of social discourse for appreciation. Conclusionally, the experience and the new vision for transmission of passing down education of the traditional dance are required to be based on the appreciation of the rationality of mutual communication and recognition of experience.