• Journal of Korean Society of Environmental Engineers
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• v.22 no.11
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• pp.1985-1994
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• 2000

This research was designed to investigate the effect of initial adsorbed amount of phenol, temperature, and pH on the desorption reaction of phenol from spent activated carbon loaded with phenol. Methanol, acetone, and N,N-dimethylformamide( DMF) were used as test organic solvents. The initial adsorbed quantities of phenol investigated here were 166.1mg/g, 180.7mg/g, and 197.9mg/g. The effect of temperature was evaluated from 15 to $55^{\circ}C$ with an interval of $10^{\circ}C$, while that of pH was investigated under acidic. neutral. and alkaline conditions. The extent of phenol desorption was proportional to the strength of dipole moment such as methanol < acetone < DMF. Over 90% desorption of phenol was achieved by acetone and DMF. The quantity of des orbed phenol by the organic solvents decreases with increasing the initial adsorbed amount of phenol. DMF is affected least by the initially adsorbed amount of phenol. An increase in reaction temperature leads to higher desorption of phenol. Desorption reaction by methanol is most sensitive to the temperature. As the pH of solvents increases. the desorption rate is also increasing. At pH=12. the desorption rate of phenol by methanol increases sharply by 10%. Although methanol demonstrated the weakest desorption power. the desorption capacity of methanol would approach that of acetone and DMF by adjusting temperature and pH. Methanol may emerge as a promising solvent for removing phenol from activated carbon because of acceptable regeneration efficiency as well as relatively cheap price.

• Korean Journal of Environmental Agriculture
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• v.19 no.5
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• pp.401-418
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• 2000

1. Production of the artificial zeolite from coal ash Coal fly ash is mainly composed of several oxides including $SiO_2$ and $Al_2O_3$ derived from inorganic compounds remained after burning. As minor components, $Fe_2O_3$ and oxides of Mg, Ca, P, Ti (trace) are also contained in the ash. These components are presented as glass form resulting from fusion in the process of the combustion of coal. In other word, coal ash may refer to a kind of aluminosilicate glass that is known to easily change to zeolite-like materials by hydrothermal reaction. Lots of hot seawater is disposing near thermal power plants after cooling turbine generator periodically. Using seawater in the hydrothermal reaction caused to produce low price artificial zeolite by reduction of sodium hydroxide consumption, heating energy and water cost. As coal ash were reacted hydrothermally, peaks of quartz and mullite in the ash were weakened and disappeared, and new Na-Pl peaks were appeared strengthily. Si-O-Si bonding of the bituminous coal ash was changed to Si-O-Al (and $Fe^{3+}$) bonding by the reaction. Therefore the produced Na-Pl type zeolite had high CEC of 276.7 $cmol^+{\cdot}kg^{-1}$ and well developed molecular sieve structure with low concentration of heavy metals. 2. Utilization of the artificial zeolite in agro-environment The artificial zeolite(1g) could remove 123.5 mg of zinc, 164.7 mg copper, 184.4 mg cadmium and 350.6 mg lead in the synthetic wastewater. The removability is higher 2.8 times in zinc, 3.3 times in copper, 4.7 times in cadmium and 4.8 times in lead than natural zeolite and charcoal powder. When the heavy metals were treated at the ratio of 150 $kg{\cdot}ha^{-1}$ to the rice plant, various growth inhibition were observed; brownish discoloration and death of leaf sheath, growth inhibition in culm length, number of panicles and grains, grain ripening and rice yield. But these growth inhibition was greatly alleviated by the application of artificial zeolite, therefore, rice yield increased $1.1{\sim}3.2$ times according to the metal kind. In addition, the concentration of heavy metals in the brown rice also lowered by $27{\sim}75%$. Artificial Granular Zeolites (AGZ) was developed for the purification of wastewater. Canon exchange capacity was 126.8 $cmol^+{\cdot}kg^{-1}$. AGZ had Na-Pl peaks mainly with some minor $C_3S$ peaks in X-ray diffractogram. In addition, AGZs had various pore structure that may be adhere the suspended solid and offer microbiological niche to decompose organic pollutants. AGZ could remove ammonium, orthophosphate and heavy metals simultaneously. Mixing ratio of artificial zeolite in AGZs was related positively with removal efficiency of $NH_4\;^+$ and negatively with that of $PO_4\;^{3-}$. Root growth of rice seedling was inhibited severely in the mine wastewater because of strong acidity and high concentration of heavy metals. As AGZ(1 kg) stayed in the wastewater(100L) for 4days, water quality turned into safely for agricultural usage and rice seedlings grew normally.

• The Journal of the Korea Contents Association
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• v.8 no.6
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• pp.175-185
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• 2008

This study would be research for correlations between ethical factors and company's competitiveness of small and medium enterprises thorough recognizing of important company ethic and approaching to them theoretically. This study has collected all information which small and medium enterprises around Seoul and Kyounggi province and employing more than 5, which 134- survey are used totally. Study reveals that firstly customer and social responsibility provide Positive effects on the organization Dust, secondly CEO's views serve those positive effects as well, thirdly it is not preyed that ethical capacity of company have a positive effect on organization trust. Fourthly, organization trust has good effects on competitiveness of product and price. This results lead to some suggestions as follows. First of all, company should serves systemized value to customers and their societies. For that, it is necessary to analyse their needs and to reflect them into corporate management to build close relationship with customers and reliable marketing activities, efforts to enhance corporate images. This chain of work can make employees feel proud themselves. Secondly, supervisors including CEO should set the pace with high-consensus for ethical behaviour. Thirdly, ethical factors should be improved for improving organization trust simultaneously. Every customer, no matter they are inner or outer, should have highly required ethical understandings for their networks. Furthermore, they have to enhance organization trust and to strengthen company competitiveness through stimulating employee's courages and contribution.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.1
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• pp.73-82
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• 2020

This study was conducted to investigate the differences in carbon storage capacity of soil between the conventional and the organic agricultural cultivation followed by the assessment of their economic values. An analysis of 107 samples in the organic and the conventional rice cultivation soils in six regions across South Korea showed that the five regions, Buyeo-II, Gimhae, Sancheong-I, II and Suncheon, had higher organic soil carbon contents than those of values observed on the conventional soils with the exception of the Buyeo-I areas. Based on the results from soil carbon contents, the carbon storage were estimated to be 36.1 megagram carbon (MgC) per ha in the organic paddy soils, while its conventional paddy soils were 29.4 MgC per ha. It showed that the organic paddy soils were 23 % greater than that of its conventional paddy soils. It was estimated that the carbon trading price for economic assessment was ￦758,100 per ha in the organic paddy soil and ￦617,400 per ha in the conventional paddy soil.

• Journal of Cadastre & Land InformatiX
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• v.48 no.1
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• pp.169-186
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• 2018

The social influence of the elderly population will accelerate in a rapidly aging society. The purpose of this study is to establish a methodology for extracting vulnerable districts of the welfare of the aged through machine learning(ML), artificial neural network(ANN) and geospatial analysis. In order to establish the direction of analysis, this progressed after an interview with volunteers who over 65-year old people, public officer and the manager of the aged welfare facility. The indicators are the geographic distance capacity, elderly welfare enjoyment, officially assessed land price and mobile communication based on old people activities where 500 m vector areal unit within 15 minutes in Yongin-city, Gyeonggi-do. As a result, the prediction accuracy of 83.2% in the support vector machine(SVM) of ML using the RBF kernel algorithm was obtained in simulation. Furthermore, the correlation result(0.63) was derived from ANN using backpropagation algorithm. A geographically weighted regression(GWR) was also performed to analyze spatial autocorrelation within variables. As a result of this analysis, the coefficient of determination was 70.1%, which showed good explanatory power. Moran's I and Getis-Ord Gi coefficients are analyzed to investigate spatially outlier as well as distribution patterns. This study can be used to solve the welfare imbalance of the aged considering the local conditions of the government recently.

• Journal of Global Scholars of Marketing Science
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• v.17 no.1
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• pp.51-75
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• 2007

Dongdaemun fashion market has been successfully positioned as a main hub for non-brand fashion product distribution in Korea. One of important competitive advantages of Dongdaemun market often quoted by retail researchers is an efficiently managed network system among supply chain members. This study aimed to examine the importance of buyer-supplier relationship elements and supplier properties from buyers' perspectives (small & very small-sized fashion stores in Dongdaemun market), and to identify the determinants of the relationship length between suppliers and buyers. Survey responses of 233 stores were analyzed using EQS 6.1 for Window and SPSSWIN 10.0. The findings could be summarized as follows: First, fashion stores perceived that right delivery as the most important factor, and geographically closeness, design capability, quality, and lower price followed in order. Second, the characteristics of stores such as location, wholesaling versus retailing focusing, monthly sales, and total business length all affected the perceived importance of buyer-supplier relationship. Third, design capacity, communication, power was identified as determinants of actual relationship length with a supplier, while communication and trust were found to be determinants of future expected relationship length.

• Journal of Forest and Environmental Science
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• v.23 no.1
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• pp.11-19
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• 2007

This study was designed to analyze the economic efficiency that is needed to develop and make practical application of a mobile carbonization apparatus, which are able to make wood charcoals and pyroligneous liquid at the logging field with debris. B/C ratio was employed to make an economic analysis, and sensitivity analysis with respect to change in price and interest rates also was made. Cylindrical type is the proper type for the mobile carbonization apparatus, when important factors such as handling capacity, a carbonization time, quality of products and assembling ability were considered. It weighs 400 kg, and a three-step fold-up equipment. The size of 2 (diameter) by 2.4 m (height) carbonization equipment required 1,500 kg wood debris per batch. A forty-eight to fifty-two carbonization time produced 300 kg of wood charcoal and $45{\ell}$ of pyroligneous liquid. The average life span of the apparatus was 5 years. If the private enterprise operated 100 batch, 80 batch, and 70 batch with one apparatus, the B/C ratio of them was greater than 1, indicating that the production is economically feasible. The period to achieve a break-even point required to be 4 years in case of 100 and 80 batches to 5 years in case of 70 batch. But the private enterprises should operate at least two apparatus for the profits. Also, if the production was to be profitable, the prices of wood charcoals and pyroligneous liquid should be at least 750 won per kg and 700 won per liter.

• Safety and Health at Work
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• v.10 no.4
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• pp.452-460
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• 2019

Background: Monitoring and control of PM_2.5 are being recognized as key to address health issues attributed to PM_2.5. Availability of low-cost PM_2.5 sensors made it possible to introduce a number of portable PM_2.5 monitors based on light scattering to the consumer market at an affordable price. Accuracy of light scatteringe-based PM_2.5 monitors significantly depends on the method of calibration. Static calibration curve is used as the most popular calibration method for low-cost PM_2.5 sensors particularly because of ease of application. Drawback in this approach is, however, the lack of accuracy. Methods: This study discussed the calibration of a low-cost PM_2.5-monitoring device (PMD) to improve the accuracy and reliability for practical use. The proposed method is based on construction of the PM_2.5 sensor network using Message Queuing Telemetry Transport (MQTT) protocol and web query of reference measurement data available at government-authorized PM monitoring station (GAMS) in the republic of Korea. Four machine learning (ML) algorithms such as support vector machine, k-nearest neighbors, random forest, and extreme gradient boosting were used as regression models to calibrate the PMD measurements of PM_2.5. Performance of each ML algorithm was evaluated using stratified K-fold cross-validation, and a linear regression model was used as a reference. Results: Based on the performance of ML algorithms used, regression of the output of the PMD to PM_2.5 concentrations data available from the GAMS through web query was effective. The extreme gradient boosting algorithm showed the best performance with a mean coefficient of determination (R²) of 0.78 and standard error of 5.0 ㎍/㎥, corresponding to 8% increase in R² and 12% decrease in root mean square error in comparison with the linear regression model. Minimum 100 hours of calibration period was found required to calibrate the PMD to its full capacity. Calibration method proposed poses a limitation on the location of the PMD being in the vicinity of the GAMS. As the number of the PMD participating in the sensor network increases, however, calibrated PMDs can be used as reference devices to nearby PMDs that require calibration, forming a calibration chain through MQTT protocol. Conclusions: Calibration of a low-cost PMD, which is based on construction of PM_2.5 sensor network using MQTT protocol and web query of reference measurement data available at a GAMS, significantly improves the accuracy and reliability of a PMD, thereby making practical use of the low-cost PMD possible.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.6
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• pp.136-150
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• 2010

Due to the effect of indoor coverage problem, the QoS of the indoor users will be degraded dramatically, with the number of indoor users. The femto cell is a popular solution for such problems. Since the price of the femto base station is usually cheap enough, one can sets up huge number of base stations in a small indoor area to reduce the size of communication cell. In this way, the QoS of the indoor users can be improved significantly. Moreover, the data rate can also be increased. However, how to decide an ideal transmitting power according to the surrounding radio environment is not a trivial problem, that still has not been addressed well. If the transmit power of femto base station is too large, the interference to the macro users will be increased. Conversely, if the transmit power of femto base station is too small; the coverage of femto base station will be reduced. To address this problem, we propose a power configuration method in femto base station using Genetic Algorithm by investigating a new fitness function. Furthermore, we adopt the weighted sum approach to improve the user performance in different modes. The simulation results show that the proposed power configuration method can not only improves the downlink SINR, but also enhance the channel capacity for both the Macro cell systems and Femto cell systems compared with some conventional methods.

• Journal of Bio-Environment Control
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• v.10 no.4
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• pp.213-218
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• 2001

In 2000, domestic protected cultivation area was about 52,189 ha including 13,621 ha of heating greenhouses. Recently, heating cost accounts for 25 to 30% of total production cost which has been increased due to the rise of oil price, while the heating cost was about 15% in other advanced countries. To reduce the heating energy cost, the study of minimizing the heating space of greenhouse have been conducted from 1998 to 1999. The system was developed to control the heating space according to crop growth by moving horizontal curtain up and down. Installation of the heating space-control curtain in greenhouse decreased heating capacity to 264 m$^3$compared to 661.5 m$^3$in the traditional curtain, and consumpted fuel was saved about 56% point in semiforcing culture and 28% point in retarding culture of pepper. In addition, uniform distribution of air temperature and relative humidity in greenhouse environment resulted in earlier flowering and higher yields in hot pepper.