• Journal of Wetlands Research
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• v.14 no.1
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• pp.21-33
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• 2012

The dominant land use at the Seonakdong river watershed is paddy and forest areas and the Seonakdong river stands still. Thus, the water pollution in the Seonakdong river is becoming more serious for the non-point source. In this study, SWAT(Soil and Water Assessment Tool) model was evaluated for simulation of flow and water quality behaviors in Seonakdong river. To perform the calibration and verification of the SWAT model, the measurements of discharge and water quality were performed for the period from 2006 to 2007 at 5 gauging stations in Seonakdong river. The $R^2$ value for discharge and water quality were 0.86 and 0.70 respectively for calibration after the sensitive analysis. The $R^2$ value for discharge and water quality were 0.81 and 0.51 respectively for verification. The simulation results show that BOD value in the river tends to decrease after the opening of gates and the patterns of TN and TP concentrations are similar as that of BOD. The gate operators need to determine how to supply water in drought season for effective water quality improvement. This study shows that the SWAT model, which is capable of simulating hydrologic and water quality behaviors temporarily and spatially at watershed scale, could be used to get the gate operation rule for the water quality management in Seonakdong river.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.2B
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• pp.130-137
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• 2012

In this paper, we propose core and edge router architectures with LPI(Low Power Idle) for reducing energy consumption in OBS networks. The proposed core router architecture is comprised of a BCP switch, a burst switch, line cards and sleep/wake controller for LPI. When the offered load of network is low, sleep/wake controller can change the state of the core router line card from active to sleep state for saving the energy after receiving network control packet. The edge router consists of a switch for access line card, a SCU and OBS edge router line cards. The LPI function in edge router line card is performed through network level control by network control packet, individually. Additionally, PHY/transceiver modules can transition active state to sleep state when burst assemble engine generates new bursts. To evaluate the energy saving performance of proposed architecture with LPI, the power consumption of each router is analyzed by using data sheet of commercial router and optical device. And, simulation is also performed in terms of sleep time of PHY/Transceiver through OPNET.

• Journal of the Korean Geosynthetics Society
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• v.12 no.4
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• pp.11-19
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• 2013

Recently despite the development of analysis program and construction technologies, collapse at the many earth retaining wall construction site of the structure due to the economic and human damage has occurred. The results of geothechnical investigation studies field, it was found to differ from the results of the original design. There may be errors parameters calculated from the results of ground investigation in such a case. And it can be estimated that it is irrational to behavior analysis of the earth retaining wall were analyzed by utilizing the parameters. And in this study, parameters that affect the earth retaining wall the correlations were analyzed using elasto-plastic method. Analysis method was changed various parameters (cohesion, subgrade reaction coefficient, load condition) applied to the elasto-plastic method. And due to a change in the behavior of earth retaining wall materials were analyzed. As a result, the cohesion greatly affects the behavior of earth retaining wall materials in various parameters. For this reason, the results of the geothechnical investigation, confirmation of the actual ground is very important in the design of the earth retaining wall. And, calculating accurate and reasonable of the cohesion of the various parameters is very important.

• Journal of The Korean Association of Information Education
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• v.11 no.1
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• pp.21-28
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• 2007

Along with the development of telecommunication technology, educational role has been considerably changed and NEIS is introduced and operated for the digital educational administration. However, the function of NEIS is so limited when operated in each school. As a result, Korean government prepares the plan to install and operate a new School Affairs System by separating 3 areas from 27 areas of NEIS. School Affairs System has been used in schools since March, 2006. In this regard, this study attempts to analyze the current status and tasks of using the system in elementary schools. The result of the study shows that about 67% teachers use the system once or twice a day. Most of teachers answer that they get help from other teachers if they have any problem in operating the system. Many teachers affirmatively answer to the design and function of the system, and they are satisfied with the convenience and efficiency of the system. However, they feel difficulty to be familiar with the system sue to the frequent change. The importance of electronic certificate and personal information is well recognized and managed in terms of the security of the system. Facilities need to be well equipped, and information exchange system need to be developed to accept each school's request to improve the function of the system. In addition, applicable laws need to be arranged, clear guideline of educational administration agency and principal's strong intention are required to relieve teachers' work load.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.1
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• pp.23-29
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• 2018

In knee implants, contact pressure has a significant effect on wear. In this study, finite element analysis is performed using the knee implant model developed in the previous research. The contact pressures for a total of 10 knee implant materials combinations were analyzed using the combinations actually used in research and industry. In order to calculate the contact pressure, The load was applied when the flection angle of knee was $30^{\circ}$, $45^{\circ}$ and $60^{\circ}$. The result of contact pressure revealed the smallest contact pressure in the titanium alloy-UHMWPE combination. In the case of UHMWPE, contact pressure did not change much with any material used in the femur. Compared the combination with the largest contact pressure and the smallest contact pressure, the difference was 0.77%. On the other hand, Carbon / PEEK composites showed 5.3% difference when the contact pressure was the largest and the smallest. It can be seen that when the Carbon / PEEK composite material is used as the bearing part, the material of the femoral part affects the wear. This study will contribute to the prediction of knee implant wear and minimization of wear.

• Journal of the Korea Society of Computer and Information
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• v.25 no.1
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• pp.117-124
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• 2020

In this paper, we proposed a plan to maintain comfortable indoor air quality in nursing homes by suggesting ways to reduce items temporarily exceeding the reference values through real-time concentration variation analysis of indoor air quality. Five items including PM10, CO₂, CO, VOC, and Radon are measured at nursing homes in spring (April) and autumn (September) was carried out and all of the measured items were analyzed to satisfy the criteria set by the Indoor Air Quality Control Act. As a result of the analysis of the real-time concentration change, the concentration of CO₂ was close to the reference value based on the number of occupants in the sick room. Due to the disinfectant (alcohol) used to disinfect and the auxiliary tools (adhesive) used in the operation of the program such as making and coloring, it was analyzed to temporarily exceed the standard value in the hall. In conclusion, it is possible to provide pleasant indoor air quality and contribute to securing the nursing home's competitiveness if periodic ventilation, natural disinfectant and eco-friendly product are used in consideration of the thermal environment.

• Journal of Advanced Navigation Technology
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• v.21 no.4
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• pp.377-385
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• 2017

The solar cell need the characteristic interpreting because the solar cell changes greatly according to the isolation, temperature and load in the photovoltaic development. Moreover, to get many energy in photovoltaic development need the position tracking of the sun according to the environment change. Also, The solar cells should be operated at the maximum power point. In this paper, I used microprocessor and sensor and designed to improve the efficiency of the photovoltaic system the photovoltaic position tracker device, and compared the normal photovoltaic system of fixed form with the photovoltaic system of solar position tracked form. Moreover, compared the catalogue of solar cell module and the simulation through a mathematics modelling with the solar cell's characteristic interpreting and composed an power conversion system with boost converter and voltage source inverter. Used the constant voltage control method for maximum power point tracking in boost converter control and, used the SPWM(Sinusoidal Pulse Width Modulation) control method in inverter control. The result was less then 5% when compared the catalogue of solar cell module and the simulation through a mathematics modelling. The boost rate of boost converter was similar to 167 % with the simulation.

• Journal of the Korean Society for Railway
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• v.20 no.1
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• pp.85-98
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• 2017

In general, under the repetitive dynamic load generated by rail cars running on the track, subgrade soil experiences changes of stress conditions such as deviatoric stress (${\sigma}_d$) and bulk stress (${\theta}$). Due to the repetitive change of deviatoric stress (${\sigma}_d$) with number of loadings, the resilient modulus ($M_R$) can be obtained by using the measured resilient strain (${\varepsilon}_r$) after a sufficient number of loadings. At present, no plausible and unified test method has been proposed to obtain the resilient modulus of railway track subgrade soil. In this study, a possible test method for obtaining the resilient modulus ($M_R$) of railway track subgrade soil is proposed; this test, by utilizing repetitive triaxial compression testing, can consider all the important parameters, such as the confining stress, deviatoric stress, and number of loadings. By adapting and using the proposed test method to obtain $M_R$, $M_R$ values for compacted track subgrade soil can be successfully determined using soil obtained in three field sites of railway track construction with changing water content range from OMC. In addition, shear modulus (G) ~ shear strain (${\gamma}$) relation data were also obtained using a mid-size RC test. A correlation analysis was performed using the obtained G and $M_R$ values while considering the strain levels and modes of strain direction.

• Korean Journal of Food Science and Technology
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• v.47 no.1
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• pp.13-19
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• 2015

The effects of electron beam (e-beam) irradiation at up to 10 kGy on the microbiological and physicochemical properties of dried red pepper powders were studied. Samples from Korea, China, and Vietnam were included in this study. In untreated samples, the total number of microbes, such as total aerobic bacteria, yeasts and molds, was in the range of $10^6-10^7CFU/g$. E-beam irradiation at 5 kGy reduced the microbial load by 2-4 log cycles, thus improving the hygienic quality of the samples. Moisture and pH of the samples were unchanged after e-beam irradiation. Reducing sugar content decreased at 1 kGy, followed by a gradual increase at higher radiation doses. At 5 kGy, no significant changes in the content of capsaicinoids were observed between the irradiated and control samples, while a 10 kGy dose led to a significant decrease. The content of pigments did not exhibit apparent changes with increasing dose of irradiation.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.4
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• pp.301-309
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• 2015

Purpose: When the edentulous area is restored by implant prostheses, the opposing hypofunctioned teeth will receive physiologic mechanical stimuli. This study evaluated the bone changes around the maxillary teeth opposing an implant restoration installed in the mandibular posterior area. Materials and Methods: Radiographs of the opposing teeth were taken at prostheses delivery (baseline), 3 and 6 months later. A customized film holding device was fabricated to standardize the projection geometry for the serial radiographs of the opposing teeth. The gray values of the region of interest of each digital image were compared according to time. Repeated measured analysis of variance was performed at the 95% significance level. Results: The gray values of the alveolar bone around the antagonist teeth of implants increased with time. The changes in gray values of the middle area were greater than those of the crestal area. However, the gray values of the mesial and distal areas were not different. The changes in gray values were different according to the unloaded time. Conclusion: A change in bone tissue will occur if a proper physiologic load is again applied to the bone tissues around a hypofunctioned tooth.