• Journal of Korean Library and Information Science Society
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• v.51 no.2
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• pp.355-379
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• 2020

Digital Library System(DLS) for the school library is a key access tool for school library materials. The purpose of this study was to find ways to improve the accessibility of materials through analysis of students' information search behavior in DLS. Data were collected through recording of 42 participants' DLS search process, and questionnaire. As a result, the search success rate and search satisfaction were found to be lower when the main purpose of DLS is simple leisure reading, information needs are relatively ambiguous, and when user experiences the complicated situations in the search process. The satisfaction level of search time sufficiency was the highest, and the search result satisfaction was the lowest. Besides, there was a need to improve DLS, such as integrated search of other library collection information, the recommendation of related materials, the print output of collection location, voice recognition through mobile apps, and automatic correction of search errors. Through this, the following can be suggested. First, DLS should complement the function of providing career information by reflecting the demand of education consumers. Second, improvements to DLS functionality to the general information retrieval system level must be made. Third, an infrastructure must be established for close cooperation between school library field personnel and DLS management authorities.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.1
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• pp.8-16
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• 1981

A mathematical model based on the water flow equation was developed with the Ohm's analogy and the partial differential equations. Simulation of water uptake was performed by numerically solving the equations with the aid of a differential equation solver, DGEAR in IMSL package, in FORTRAN version. The input data necessary were climatological parameters (temperature, solar radiation, humidity and wind speed). plant parametors (leaf water potential, leaf area, root conductivity and root length density) and soil parameters (hydraulic conductivity and The graphical comparison of the simulated and measured water contents as the functions of time showed good agreement, but there still was some disparity due to possible inacouracy of the field measured parameters. The simulated soil evaporation showed about 2 mm/day early in the growing period and dropped to about 0.4 mm/day as the full canopy developed and the soil water depleted. During the dry period, soil evaporation was as low as 0.1 mm/day. The transpiration was as high as 5mm/day. Deep percolation calculated from the flux between the 180-cm layer was about 0.2mm/day and became smaller with time. After the soil water of upper layers depleted, the flux reversed showing capillary rise. The rate of the capillary rise reached about 0.07mm/day, which was too low to satisfy water uptake of the root system. Therefore, to increase use of water in deep soil, expansion of the root system is necessary.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.4
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• pp.423-430
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• 2019

The convergence of the automotive industry and the ICT technology can be broadly divided into the commercial service sector and the Cooperative-ITS (C-ITS) service sector. The C-ITS service sector is using V2X communication technology as a field that aims to provide safer transportation, more green and efficient transportation, and more predictable and productive mobility. The recent convergence of self-driving cars and connected cars requires high data rates, low transmission delays, and low transmission error rates. Interest in comparison of performance between WAVE and C-V2X (LTE-V2X, 5G-V2X) has been amplified and application services by communication technology are being studied. In this paper, we design the application performance evaluation method of Hybrid V2X communication system and confirm that the decrease of packet error rate (PER) performance is caused by the increase of communication distance, not the vehicle speed.

• Korean Journal of Culture and Social Issue
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• v.12 no.1
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• pp.103-128
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• 2006

The present study investigated individuals' perception of important social issues in Korea. Based on previous research(Hahn, 1994; Hahn & Kang, 2000), a checklist containing 370 social issues was created. This checklist was administered to 1600 Koreans(812 college students, 788 adults) residing in 5 regional areas in Korea during the period of December 2004 and February 2005. Data were analyzed by the respondents' age, sex, and residing areas, and findings were compared to those of the two previous studies conducted in 1994 and 1999. Major findings of the study are as follows. First, across the three surveys, over 50% of the respondents consistently indicated the following four items as important social issues in the Korean society: political corruption, environmental pollution, the education system that is driven too much for college entrance, employment difficulty for local college graduates. Second, more than 50% of the respondents in the current survey indicated the following 12 items as important social issues that must be resolved: high unemployment rate, political corruption, environmental pollution, education system, overall difficulty of getting jobs, the nation's distrust in politics, hardships of life among the working classes, political incompetence, people with defective personal credit standings, employment difficulty for local college graduates, political instability, corruption of public servants. Third, analyses on the top 30 social issues across the three surveys revealed a positive and significant rank-order correlation for a five-year period(i.e., 1994-1999, 1999-2004), but not for a ten-year period(i.e., 1994-2004). Implications of the study and directions for future research are discussed.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.93-102
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• 2016

Vehicle-to-Grid (V2G) system, bi-direction power trading technology, enables drivers possessing electric vehicle to sell the spare electricity charged in the vehicle to power distribution company. The drivers gain profit by charging electricity in the day time of high electricity rate. In this regard, the government is preparing the policies of building and supporting V2G infrastructure and demanding the potential consumers' preference for the V2G system. This paper attempts to analyze the consumers' preference using the data from obtained a survey of randomly selected 1,000 individuals. To this end, choice experiment, an economic technique, is employed here. The attributes considered in the study are residual amount of electricity, electricity trading hours, required plug-in time, and price measured as an amount additional to current gasoline vehicle price. The multinomial logit model, which requires the assumption of 'independence of irrelevant alternatives', is applied but the assumption could not be satisfied in our data. Thus, we finally utilized nested logit model which does not require the assumption. All the parameter estimates in the utility function are statistically significant at the 10% level. The estimation results show that the marginal willingness to pay (MWTP) for one hour increase in electricity trading hours is estimated to be KRW 1,601,057. On the other hand, a one percent reduction in residual amount of electricity and one hour reduction in required plug-in time in V2G system are computed to be KRW -91,911 and -470,619, respectively. The findings can provide policy makers with useful information for decision-making about introducing and managing V2G system.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.31-38
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• 2020

The characteristics of ship traffic routes and the long term fluctuation in marine traf ic volume of the incoming and outgoing routes of the Yeosu Gwangyang Port were analyzed using vessel traffic data from the past 22 years and a real-time vessel traffic volume survey performed for 72 hours per year, for three years, between 2015 and 2017. As of 2017, the number of vessels passing through Yeosu Gwangyang Port was about 66,000 and the total tonnage of these ships was about 804,564 thousand tons, which is a 400 % increase from the 189,906 thousand tons shipped in 1996. Specifically, the dangerous cargo volume was 140,000 thousand tons, which is a 250 % increase compared to 1996. According to the real-time vessel traffic volume survey, the average daily number of vessels was 357, and traf ic route utilization rates were 28.1 % in the Nakpo sea area, 43.8 % in the specified sea area, and the coastal area traf ic route, Dolsan coastal area, and Kumhodo sea area showed the same rate of 6.8 %. Many routes meet in the Nakpo sea area and, parallel and cross passing were frequent. Many small work vessels entered the specific sea area from the neighboring coastal area traffic route and frequently intersected the path of larger vessels. The anchorage waiting rate for cargo ships was about 24 %, and the nightly passing rate for dangerous cargo ships such as chemical vessels and tankers was about 20 %. Although the vessel traffic volume of Yeosu Gwangyang Port increases every year, the vessel traffic routes remain the same. Therefore, the risk of accidents is constantly increasing. The route conditions must be improved by dredging and expanding the available routes to reduce the high risk of ship accidents due to overlapping routes, by removing reefs, and by reinforcing navigational aids. In addition, the entry and exit time for dangerous cargo ships at high-risk ports must be strictly regulated. Advancements in the VTS system can help to actively manage the traffic of small vessels using the coastal area traffic route.

• Progress in Medical Physics
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• v.21 no.3
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• pp.253-260
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• 2010

Most brachytherapy treatment planning systems employ a dosimetry formalism based on the AAPM TG-43 report which does not appropriately consider tissue heterogeneity. In this study we aimed to set up a simple Monte Carlo-based intracavitary high-dose-rate brachytherapy (IC-HDRB) plan verification platform, focusing particularly on the robustness of the direct Monte Carlo dose calculation using material and density information derived from CT images. CT images of slab phantoms and a uterine cervical cancer patient were used for brachytherapy plans based on the Plato (Nucletron, Netherlands) brachytherapy planning system. Monte Carlo simulations were implemented using the parameters from the Plato system and compared with the EBT film dosimetry and conventional dose computations. EGSnrc based DOSXYZnrc code was used for Monte Carlo simulations. Each $^{192}Ir$ source of the afterloader was approximately modeled as a parallel-piped shape inside the converted CT data set whose voxel size was $2{\times}2{\times}2\;mm^3$. Bracytherapy dose calculations based on the TG-43 showed good agreement with the Monte Carlo results in a homogeneous media whose density was close to water, but there were significant errors in high-density materials. For a patient case, A and B point dose differences were less than 3%, while the mean dose discrepancy was as much as 5%. Conventional dose computation methods might underdose the targets by not accounting for the effects of high-density materials. The proposed platform was shown to be feasible and to have good dose calculation accuracy. One should be careful when confirming the plan using a conventional brachytherapy dose computation method, and moreover, an independent dose verification system as developed in this study might be helpful.

• Journal of Korean society of Dental Hygiene
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• v.8 no.4
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• pp.19-30
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• 2008

This study reached the following conclusions as a result of carrying out the questionnaire survey of self-descriptions for the satisfaction after the citizens of Daejon uses the dental clinics, in order to identify the factors of satisfaction to the medical services of such dental clinics to be utilized in the patient management by dental hygienists, provide the basic data to provide the medical services desired by patients. 1. 43.9% men responded to the facilities and 56.1% women to the atmosphere for the standards of selection of dental clinics by general characteristic, and the college graduates or more to the kindness (38.2%), high-school graduates (43.2%) and middle-school graduates (25.9%) or less to the close distance for the level of educational attainment (p=0.009), which was meant to have a statistical significance. 2. The execution of reservation system for the dental clinics showed 54.7%, the reserved time was observed upon the execution of such reservation system, the dental clinics where they practice such system were 40.6%, and the confirmation methods was done through the telephone with 62.5%. 3. The experience of fear upon the dental treatment showed 74.6%. The type of fear showed the machine sound (48.7%) for men and cry of others for women (70.8%) at the highest. 70% of those under 30 at the age responded to the sharp instruments at the highest. 83.3% of Yousung-gu showed the highest by responding to the cry of others for the residential areas. The statistically significant difference was shown in both the age and residential area (p=0.000). 4. Women showed higher in the distribution of gender for the sterilization of instruments for the external satisfaction of dental clinics(p=0.000) and those under 30 at the age showed the highest with 2.98${\pm}$0.95(p=0.001). Seo-gu (3.48${\pm}$0.77) was the highest for the residential area (p=0.000), and there was statistically significant differences in the gender, age and residential area. 5. Men showed higher satisfaction than women in the clean state and the statistically significant differences were shown (p=0.000) at the age as the high satisfaction was shown for those under 30 at the age (2.35${\pm}$0.79), those having the income not less than 10 million won and not more than 20 million won (2.43${\pm}$0.78), and Seo-gu (2.63 ${\pm}$0.69) for the residential area. 6. For the internal satisfaction of dental clinic by users for the medical services in the dental clinics, 61.1% women responded to no in the ability of solving the inconvenience in the service process, and showed low ability of solving the inconvenience from 30 at the age (26.2%) and by responding to Dong-gu (22.1%) for the residential area, showing statically significant differences(p=0.000). For the re-use of dental clinics, 46.6% men (p=0.043) for the gender, 24.3% under 30 at the age and 22.9% of Dong-gu for the residential area responded to the re-use, showing statistically significant differences for the gender and residential area (p=0.000). 7. The dissatisfaction showed a high rate of 69.5% for the satisfaction to the medical services of dental clinics. 46.2% men responded to the pain and women to the feeling of foreign substance for the reason of dissatisfaction while those under 30 at the age showed 55.6% for others, those between 50 and 59 41.7% for the feeling of foreign substance. 86.3% carried out the education for cautions after the treatments and most people turned out that they do not carry out the continuous health management of mouth as 20.5% responded to that they carry out such health management.

• Membrane Journal
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• v.22 no.2
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• pp.95-103
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• 2012

To treat nitrate and non-biodegradable organics effectively in sewage, industrial wastewater and livestock wastewater, the activated sludge process integrated by a membrane separation and a porous electrode- electrolysis was proposed and its efficiency was investigated. The proposed system was consisted of 3 processes; activated sludge, membrane filtration and electrolysis. In the study, the membrane filtration played a role in reducing the load of the electrolysis to operate the proposed process stably. The electrolysis consisted of a porous electrode to increase the efficiency due to the extension of the specific surface area. Additionally, redox reaction in the electrolysis was induced by decomposing influent water as current was applied. As a result, hydrogen free radicals and oxygen radicals as intermediates were produced and they acted as oxidants to play a role in decomposing non-degradable organics. It was environmentally-friendly process because intermediates produced by porous electrode were used to treat waste matters without supplying external reagent. Experimental data showed that the proposed process was more excellent than activated sludge process. SS removal efficiencies of the proposed process, membrane filtration and activated sludge process were about 100%, about 100% and about 90%, respectively. COD removal efficiencies of the proposed system, membrane filtration and activated sludge process were about 92%, about 84% and about 78%, respectively. T-N removal efficiencies of the proposed system, membrane filtration and activated sludge process were about 88%, about 67%, and about 58%, respectively. The SS data showed that SS was efficiently removed in the single of the membrane filtration. The COD/T-N data showed that COD/T-N of membrane hybrid process was treated by removing a little soluble organics and SS, and that COD/T-N of electrolysis hybrid process was treated by oxidize organics with high removal rate.

• Journal of Korea Water Resources Association
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• v.47 no.2
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• pp.145-159
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• 2014

This study is to evaluate the future climate change impact on turbidity water and eutrophication for Chungju Lake by using CE-QUAL-W2 reservoir water quality model coupled with SWAT watershed model. The SWAT was calibrated and validated using 11 years (2000~2010) daily streamflow data at three locations and monthly stream water quality data at two locations. The CE-QUAL-W2 was calibrated and validated for 2 years (2008 and 2010) water temperature, suspended solid, total nitrogen, total phosphorus, and Chl-a. For the future assessment, the SWAT results were used as boundary conditions for CE-QUAL-W2 model run. To evaluate the future water quality variation in reservoir, the climate data predicted by MM5 RCM(Regional Climate Model) of Special Report on Emissions Scenarios (SRES) A1B for three periods (2013~2040, 2041~2070 and 2071~2100) were downscaled by Artificial Neural Networks method to consider Typhoon effect. The RCM temperature and precipitation outputs and historical records were used to generate pollutants loading from the watershed. By the future temperature increase, the lake water temperature showed $0.5^{\circ}C$ increase in shallow depth while $-0.9^{\circ}C$ in deep depth. The future annual maximum sediment concentration into the lake from the watershed showed 17% increase in wet years. The future lake residence time above 10 mg/L suspended solids (SS) showed increases of 6 and 17 days in wet and dry years respectively comparing with normal year. The SS occupying rate of the lake also showed increases of 24% and 26% in both wet and dry year respectively. In summary, the future lake turbidity showed longer lasting with high concentration comparing with present behavior. Under the future lake environment by the watershed and within lake, the future maximum Chl-a concentration showed increases of 19 % in wet year and 3% in dry year respectively.