• Journal of Korean Society for Atmospheric Environment
• /
• v.9 no.2
• /
• pp.147-153
• /
• 1993

From March 1990 to August 1991, every each 5mm bulk precipitation samples were collected at one residental area in Taejon City to investigate chemical characteristics of acid rain. Major ion concentrations of rain samples $(pH, SO_4^{2-}, NO_3^-, CL^-, NH_4^+, Na^+, K^+, Ca^{2+}, Mg^{2+})$ were analysed and compared with the concentration of air pollutants (T. S. P, $SO_2, NO_x$) that were measured by Ministry of Environment. The results of statistical analysis are as followings. Rain pH was relatively high on October and January and relatively low on August, November and February. Major anion is sulfate, and it's concentration is 2.36 times higher than nitrate's, and major cations are ammonium, sodium and calcium ion. Monthly variation of sulfate and calcium concentrations are higher than the others. Ion concentration and rain pH were correlated negatively with rainfall amount. Major ions in rain samples were $SO_4^{2-}, NO_3^-, NH_4^+, Ca^{2+}$ and regression equations are proposed by multiple regression of measured data. Also, regression equation between air pollutants(T. S. P, $SO_2$) and $SO_4^{2-}, Na^+, K^+, Ca^{2+}, Mg^{2+} ions in rain samples were made. From this wer can predict rain pH.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.13 no.4
• /
• pp.10-17
• /
• 2010

The objectives of this study were to compare the growth of Vitex rotundifolia as affected by the difference of soil depth and mixture ratio in a shallow-extensive green roof module system, and to identify the level of soil thickness and mixture ratio as suitable growing condition to achieve the desired plant growth in green roof. Different soil thickness levels were achieved under 7cm, 15cm and 25cm of shallow-extensive green roof module systems made by woody frame of $500{\times}500{\times}300mm$. Soil mixture ratio were eight types for perlite : peatmoss : leafmold = 7 : 1 : 2 (v/v/v, $P_7P_1L_2$), perlite : peatmoss : leafmold = 6 : 2 : 2 (v/v/v, $P_6P_2L_2$), perlite : peatmoss : leafmold = 5 : 3 : 2 (v/v/v, $P_5P_3L_2$), perlite : peatmoss : leafmold = 4 : 4 : 2 (v/v/v, $P_4P_4L_2$), only sand ($S_{10}$), sand : leafmold = 7 : 3 (v/v, $S_7L_3$), sand : leafmold = 5 : 5 (v/v, $S_5L_5$) and only leafmold ($L_{10}$). The growth response of Vitex rotundifolia had fine and sustain condition in $P_6P_2L_2$, $P_5P_3L_2$ and $P_4P_4L_2$., Especially, in case of $P_6P_2L_2$, growth response appeared to be good even in soil thickness 7cm, which showed low survival rates of Vitex rotundifolia in other soil mixtures. Tree height, root diameter, photosynthesis and chlorophyll contents tended to increase with increased soil thickness.

• Journal of Korean Society on Water Environment
• /
• v.18 no.2
• /
• pp.169-187
• /
• 2002

The effects of important parameters such as reaction time and pH on the Fenton's process were evaluated using a batch reactor. It was proven that organic materials and heavy metals in leachate could be successfully removed by Fenton's reagent. Favorable operation conditions were investigated. It was observed that the reaction between ferrous iron and hydrogen peroxide with the production of hydroxyl radical was almost complete in 10 minutes. That is, the oxidation of organic materials by Fenton's reagent was so fast that it was complete in 30 minutes with batch experiments. With the formation of carbonic acid, pH of the batch reactor decreased to favorable acidic conditions without acid addition. The oxidation of organic materials in the leachate showed a pH dependence and was most efficient in the pH range of 2-3.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2001.09a
• /
• pp.19-22
• /
• 2001

The effects of pH on the sequential sorption/desorption of chlorinated phenols (2-chlorophenol, 2.4-dichlorophenol and 2,4,5-trichlorophenol) in HDTMA-montmorillonite were investigated by maintaining pH 4.85 or 9.15 in the sequential batch sorption and desorption experiments. The chlorinated phenols are hydrophobic ionizable orginic compounds; they can exist as either neutral (pH << pKa) or anionic (pH >> pKa) forms. Among the tested chlorinated phenols, 2,4,5-trichlorophenol showed the highest sorption affinity at pH 4.85 as expected by the $K_{ow}$ . Neutral speciation at pH 4.85 exhibited higher sorption affinity than anionic speciation at pH 9.15. Our results indicates that desorption of chlorinated phenols is strongly dependent on pH of the aqueous phase. Freundlich model was used to analyze the single-solute sorption/desorption results. The ideal adsorbed solution theory(IAST) was employed to predict the hi-solute sorption/desorption equilibria.

• Journal of Digital Convergence
• /
• v.17 no.10
• /
• pp.37-47
• /
• 2019

The purpose of this study was to examine the relationship between nursing work environment perception, career barriers and career identity of graduating grade nursing college students and factors affecting career identity. The data collection was conducted from June 3 to June 28, 2019 with 212 students in grade 4 of C University in S city. Career identity, $2.65{\pm}0.46$, $3.23{\pm}.57$, and $2.28{\pm}.77$, respectively. Career identity was positively correlated with nursing working environment(r=-.654, p<.001) and career barrier(r=.319, p<.001). The nursing work environment was negatively correlated with career barriers(r=-.216, p<.001). The variables that affect the sense of course are the career barrier(${\beta}=-.527$, p=.000), recognition of nursing work environment(${\beta}=.131$, p=.014), practice satisfaction(${\beta}=-.154$, p=.009), and this variable showed an explanatory power of 50.1% on career identity. Therefore, it is necessary to make efforts at the school to enhance awareness of nursing work environment and satisfaction in practice, improve clinical practice, and lower the career barrier through support and support from hospital and nursing managers.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.8
• /
• pp.1760-1768
• /
• 2004

A P2P is a method that can share and exchange on digital resources through a direct connection on personnel without a central server. In this paper, we apply a P2P technology to a traditional electronic commerce method so that a seller and a customer can perform a commercial transaction through a direct communication. As such a result, we propose a new e-Commerce model on P2P environment to assure fairness in commercial transactions. To achieve our goal, we put an escrow server which is responsible for guarantee fair contents delivery and payment for the contents between a seller and a customer. When a customer buys content, he first obtains reputation values implicating reliability for the content and refers to these values to determine purchase. The proposed scheme, we can improve the reliability for the purchasing content and provide the fairness to both a seller and a customer simultaneously.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.15 no.1
• /
• pp.104-109
• /
• 2005

Context-awareness is an important element that can provide service of good quality according to users' surrounding environment and status in ubiquitous computing environment. Information gathering tools for context-awareness use small size mobile devices which have easy movement and a mobile agent in mobile device. Now, Mobile agents are consuming much times and expense to collect and recognize each users' context information. Therefore, needs research about structure for users' context information awareness in early time to reduce mobile agent's load. This paper proposes a P2P mobile agent structure that mikes filtering techniques and a P2P agent in mobile agent. The proposed structure analyzes each user's context information in same area, and groups users who have similar preference degree. Grouped users share information using a P2P mobile agent. Also this structure observes and learns to continue on users' action and service, and measures new interrelation.

• Journal of Digital Contents Society
• /
• v.14 no.1
• /
• pp.89-95
• /
• 2013

Many peer-to-peer (p2p) systems have been studied in distributed, ubiquitous computing environments. Distributed hash table (DHT)-based p2p systems can improve load-balancing even though locality utilization and user mobility are not guaranteed. We propose a mobile locality-based hierarchical p2p overlay network (MLH-Net) to address locality problems without any other services. MLH-Net utilizes mobility features in a mobile environment. MLH-Net is constructed as two layers, an upper layer formed with super-nodes and a lower layer formed with normal-nodes. The simulation results demonstrate that MLH-Net can decrease discovery routing hops by 13% compared with JXTA and 69% compared with Chord. It can decrease the discovery routing distance by 17% compared with JXTA and 83% compared with Chord depending on the environment.

• Korean journal of food and cookery science
• /
• v.26 no.4
• /
• pp.413-421
• /
• 2010

The purpose of this study was to improve the satisfaction of college foodservice customers by analyzing the correlation between college student satisfaction with foodservice and customer loyalty. The questionnaire was distributed to 480 customers at six universities in Busan. The average customer satisfaction score was 2.76, and customer satisfaction was highest with food, followed by sanitation, environment, and service (in decreasing order). Customers reported the frequency with which they were satisfied when using university foodservice operations (on an increasing scale from "almost never" to "more than five times") in four areas: food (p<0.001), service (p<0.01), sanitation (p<0.05), and environment (p<0.001). The average scores of customer loyalty, intent to purchase again, intent to advertise by word-of-mouth, and intent to switch were 2.67, 2.83, 2.52, and 2.67, respectively, and these scores demonstrated differences according to frequency of foodservice use (p<0.001). Food, service, sanitation, and environment correlated significantly (+) with customer loyalty. Intent to repeat purchase showed the highest correlation with food quality (p<0.05), and intent to advertise by word-of-mouth and to continue patronizing foodservice demonstrated the highest correlations with service (p<0.01). After classifying customers into four groups according to customer satisfaction and loyalty, a comparison was done to determine satisfaction and loyalty by each customer strata. In the "loyalist" group, satisfaction with environment and the intent to advertise by repurchase were significantly higher than in the other groups (p<0.001). In "defectors" group, satisfaction with service and the intent to advertise by word-of-mouth were significantly lower than in the other groups (p<0.001).

• Journal of Digital Convergence
• /
• v.13 no.5
• /
• pp.245-250
• /
• 2015

The P2P technology is becoming a technology for receiving a service, such as the latest YouTube and Facebook. P2P technology can be easily downloaded to a large amount of multimedia content over a distributed environment. However, pictures, music, a large amount of multimedia content such as videos each user is unable to manage the content management operating smoothly because, Song communication processing overhead caused when the reception is likely to remain the problem. In this paper, we propose a convergence content management technique that provides a low communication overhead of the frequency of use of the convergence content when trying to provide a large amount of convergence content to users in a distributed environment. Our method can be used to select the appropriate frequency is high among the shared content on the P2P multimedia environments that are distributed across a frequency of use of the convergence content and provides the service. Experimental evaluation proposed method, the convergence content browsing speed than conventional techniques improved communication about 13.3% and reduced overhead to about 9.5%.