• Korean Journal of Soil Science and Fertilizer
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• v.48 no.1
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• pp.1-7
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• 2015

Global population is expected to reach nine billion in 2050 and the total demand for food is expected to increase approximately by 60 percent by 2050 as compared to 2005. Therefore, it is important to increase crop production in order to meet the global demand for food. Slow release fertilizers have been developed and designed in order to improve the efficiency of fertilizers. Mineral-based slow release fertilizers are useful because the minerals have a crystalline structure and are environmentally friendly in a soil. This review focuses on slow release fertilizers based on montmorillonite, zeolite, and layered double hydroxide phases as a host for nutrients, especially N. Urea was successfully stabilized in the interlayer space of montmorillonite by the formation of urea-Mg or Ca complex, $[(Urea)_6Mg\;or\;Ca]^{2+}$ protecting its rapid degradation in soils. Naturally occurring zeolites occluded with ammonium nitrate and potassium nitrate by molten salt treatment could be used as slow release fertilizer because the occlusion process increased the capacity of zeolites to store nutrients in addition to exchangeable cations. Additionally, surface-modified zeolites could also be used as slow release fertilizer because the modified surface showed high affinity for anionic nutrients such as nitrate and phosphate. Moreover, there were attempts to develop and use synthetic layered double hydroxide as a carrier of nitrate because it has positively charged layers which electrostatically bond nitrate anions. Kaolin was also tested by combining with a polymer or through the mechanical-chemical process for slow release of nutrients.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.7
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• pp.706-712
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• 2014

The inverters used to drive Brushless DC motors (BLDC) include switching devices such as FETs and the faults in FETs cause severe performance degradation in systems where a BLDC acts as actuator. This paper presents a fault detection and isolation method for the FETs of an inverter for BLDC motor control systems, which is based on the EKF (Extended Kalman filter). Firstly, an equivalent circuit model for a BLDC motor plus its inverter system was derived. Secondly, a state-space equation was established, where the on-resistance of the FETs is expressed as a state variable and the EKF equation estimates the on-resistance. If the estimated resistance differs greatly from the known value, it can be asserted that there is a fault on that FET. Thirdly, the local convergence of the established EKF was proved. Finally, through the experiments, the performance of the proposed method was verified. The results show that the on-resistance is estimated close to the value specified in the FET data sheet in normal operation, whereas the estimated resistance is a much larger value than the normal one in case an FET fault occurs. Therefore, it is confirmed that the proposed fault detection and isolation method works appropriately in real systems.

• Journal of the Korean Society of Earth Science Education
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• v.8 no.2
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• pp.183-192
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• 2015

The purpose of this study was to identify STEAM education program fit for club activities in consideration of the present curriculum and investigate its effect on science club students' self-efficacy and attitude toward science by applying it to science club students. In consideration of such chapters as 'Solar System' and 'Exosphere and Space Development' in the 2009 Revised Curriculum, this study developed a STEAM education program related to the observation of the solar system and the measurement of a distance of the stars in consideration of the present curriculum. For this study we selected 14 science club students in H Middle School, located in G Province and applied a 7 weeks' program to them. To find out change in their self-efficacy and attitude toward science, this study conducted tests of self-efficacy and attitude toward science for a single group before and after introducing this program and analyzed the results. The results of this study could be summarized as below. Firstly, science club activities with this STEAM education program applied improved students' self-efficacy significantly. Secondly, there was a significant difference found in students' attitude toward science through science club activities with this STEAM education program applied as they showed higher scores in the attitude toward science in the posttest than the pretest. Lastly, despite a research limit that this science inquiry program was conducted for a short period of time, this program was found to have positive effect on the improvement of students' self-efficacy and attitude toward science.

• Journal of Fashion Business
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• v.13 no.1
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• pp.152-166
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• 2009

By virtue of the development of mass media, the cinema, the composite space art taking the visual and auditory elements together, exhibits the actual life of the realities, thereby having a mutually close relationship to social, cultural and economic fields and continuing to generate the fashion code as well as reflecting the image of the times. Especially, fashion style in movies delivers their image and atmosphere and becomes the means for containing the personality, spiritual world and inner thinking of the characters in the movie and inducing its plot. Therefore, this study was intended to make clear that fashion fuses and shares with a diversity of genres such as movies and the like, becomes the cultural model that proceeds to create a new culture in relation to daily life and induces and presents the trend of contemporary fashion. For this purpose, this study attempted to analyze fashion style in the movie. Lolita is the fiction published by the Russian?American writer Vladimir Nabokov($1899{\sim}1977$) in 1954. It is the fiction that portrays the unethical love between Humbert, a middleaged man, and Lolita, a girl in her 10s. It was cinematized by the director Stanley Kubrick for the first time in 1962 and revived by the movie director Adrian Lyne in 1997. The character of Lolita has a younger look like a girl and looks immature in the movie directed by the movie director Stanley Kubrick and the movie director Adrian Lyne. But the character of Lolita has the commonality that she showed an incomplete female image of having a sexually freewheeling thinking. Thereby, this study sought to prove that the created fashion style of the character in the film not only became the clue to enable us to know the time and space background in the film but also helped the film develop effectively by performing a role of portraying the character in the movie. And it attempted to present that it becomes both the foundation for leading the fashion trend shown in contemporary fashion and the code of mass culture. Fashion style of Lolita in the movie appears to be reflected diversely in mass culture as well as fashion style in the contemporary times.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.01a
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• pp.145-150
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• 2001

A Controlled Ecological Life Support System(CELSS) is essential for man to live a long time in a closed space such as a lunar base or a mars base. Such a system may be an extremely complex system that has a lot of facilities and circulates multiple substances,. Therefore, it is very difficult task to control the whole CELSS. Thus by regarding facilities constituting the CELSS as agents and regarding the status and action as information, the whole CELSS can be treated as multi-agent system(MAS). If a CELSS can be regarded as MAS the CELSS can have three advantages with the MAS. First the MAS need not have a central computer. Second the expendability of the CELSS increases. Third, its fault tolerance rises. However it is difficult to describe the cooperation protocol among agents for MAS. Therefore in this study we propose to apply reinforcement learning (RL), because RL enables and agent to acquire a control rule automatically. To prove that MAS and RL are effective methods. we have created the system in Java, which easily gives a distributed environment that is the characteristics feature of an agent. In this paper, we report the simulation results for material circulation control of the CELSS by the MAS and RL.

• Fire Science and Engineering
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• v.19 no.3 s.59
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• pp.13-19
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• 2005

An experimental study is presented for extinguishing characteristics of liquid fuel fire by water mist containing sodium acetate trihydrate. To evaluate the extinguishing performance of water mist containing an additive, the evaporation characteristics of a water droplet on a heated surface was examined. The evaporation process was recorded by a charge-coupled-device camera. Also, small-scale extinguishing tests were conducted for n-heptane pool fire in ventilated space to measure flame temperature variation. The average evaporation rate of a water droplet containing an additive was lower than that of a pure water droplet at a given surface temperature due to the precipitation of salt in the liquid-film and change of surface tension. In case of using an additive, the flame temperature was lower than that of pure water at a given discharge pressure and it was because the momentum of a water droplet containing an additive was increased reducing flame size. And also dissociated metal atoms, sodium, were reacted as a scavenger of the major radical species OH^-,\;H^+$ which were generated for combustion process. Moreover, at a high pressure of 4MPa, the fire was extinguished through blowing effect as well as primary extinguishing mechanisms.

• Radiation Oncology Journal
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• v.24 no.2
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• pp.110-115
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• 2006

Purpose: This study was performed to determine the prognostic factors influencing relapse pattern, overall and disease-free survival in patients treated with postoperative radiotherapy for endometrial carcinoma. Materials and Methods: The records of 54 patients with endometrial adenocarcinoma treated postoperative radiotherapy at Pusan National University Hospital between April 1992 and May 2003 were reviewed retrospectively. Median age of the patients was 55 (range $35{\sim}76$). The distribution by surgical FIGO stages were 63.0% for 0Stage I, 14.8% for Stage II, 22.2% for Stage III. All patients received postoperative external radiotherapy up to $41.4{\sim}54Gy$ (median: 50.4 Gy). Additional Intravaginal brachytherapy was app led to 20 patients (37.0% of all). Median follow-up time was 35 months ($5{\sim}115$ months). Significant factors of this study: histologic grade, Iymphovascular space invasion and myometrial invasion depth were scored (GLM score) and analyzed. Survival analysis was peformed using Kaplan-Meier method. The log-rank test was used for univariate analysis and the Cox regression model for multivariate analysis. Results: 5-year overall and disease-free survival rates were 87.7% and 871%, respectively. Prognostic factors related with overall and disease-free survival were histologic grade, Iymphovascular space invasion and myometrial invasion according to the univariate analysis. According to the multivariate analysis, Iymphovascular space invasion was associated with decreased disease-free survival. GLM score was a meaningful factor affecting overall and disease-free survival (p=0.0090, p=0.0073, respectively) and distant recurrence (p=0.0132), which was the sum of points of histologic grade, Iymphovascular space Invasion and myometrial invasion. Total failure rate was 11% with 6 patients. Relapse sites were 2 para-aortic Iymph nodes, 2 lungs, a supraclavicular Iymph node and a vagina. Conclusion: The prognosos in patients with endometrial carcinoma treated by postoperative radiotherapy was closely related with surgical histopathology. If further explorations confirm the system of prognostic factors in endometrial carcinoma, it will help us to predict the progression pattern and to manage.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.115-119
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• 2010

As the subjects of education has been changed from the instructors to learners, a web-based self-directed learning which can accelerate the initiative of learners and can be free from the restriction of time and space has been received attention. In this paper, the web-based self-directed learning system was designed. For the design, to make the learners build their own lecture plan, the service was designed to provide three kinds of lectures of video clip, slide lecture, and e-text lecture that were focused on various lecture contents. In addition, a learner and an assistant was man to man matched to enable the on-line mentoring for mutual communication between learners and assistants. Implementation was carried out by three sets of module - Manager, Learner and Assistant - that were applied to the real educational activities. The survey on satisfaction for the education, efficiency of ability improvement, and educational intelligibility for the attendants on the education showed more than 67.2% of satisfaction in satisfaction for the education. Furthermore, more than 86.9% of attendants replied that their ability were improved after the education of this system. The educational system realized in this paper shows effectiveness for the self-directed learning.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.2
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• pp.59-68
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• 2009

Currently, building a small dam located 1.16 km downstream from Geumnam Bridge is being considered in order to improve the riverine scenery of the site for Sejong City and to create a hydrophilic space. The purpose of this research is to present the appropriate dimensions of a small dam by reviewing the flood control reliability of the Geum River after the small dam is built. To establish this purpose, changes in the flood water level were compared and analyzed by changing the installation height of a small dam using 1D and 2D models. 1D HEC-RAS and 2D FESWMS models were applied to perform the numerical analysis of the reach. The results showed that flood control reliability was guaranteed when the installation height of the small dam was 5 meters or lower. From the 2D model, a more accurate result can be developed because the model could provide a two dimensional numerical analysis. The results can be used to determine the appropriate dimensions of a small dam for Sejong City.

• Progress in Superconductivity
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• v.13 no.2
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• pp.97-104
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• 2011

In the dielectric resonator method, which has been widely used for measuring the microwave surface resistance of superconductors, accuracies in the geometrical factors (G-factors) affect the uncertainty in the measured surface resistance. We compare the G-factors of short-ended sapphire resonator as obtained by using field analysis with those by using computer simulations: The former is obtained by using the analytic expressions for the electric and the magnetic field components inside the resonator, and the latter by using computer software. The G-factors as obtained by using the latter appear to be closer to those obtained by using the former as the resonator space is divided into larger number of sub-space, i.e., a tighter mesh, with a difference of ~8 % observed for a mesh of 14400 sub-spaces reduced to ~2 % for 114996 sub-spaces. Variations in the relative uncertainty in the surface resistance of typical $YBa_2Cu_3O_{7-\delta}$ superconductor films with those in the G-factors are studied, which provides an upper limit of the relative uncertainty in the G-factors required for realizing the target uncertainty in the surface resistance. These results could be useful in estimating the optimum number of meshes for obtaining the G-factors through computer simulations.