• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.4
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• pp.319-328
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• 2005

This paper describes a compartment dynamic model for evaluating the contamination level of kritium in agricultural plants exposed by accidentally released tritium. The present model uses a time-dependent growth equation of plant so that it can predict the effect of growth stage of plant during the exposure time. The model including atmosphere, soil and plant compartments is described by a set of nonlinear ordinary differential equations, and is able to predict time-dependent concentrations of tritium in the compartments. To validate the model, a series of exposure experiments of HTO vapor on Chinese cabbage and radish was carried out at the different growth stage of each plant. At the end of exposure, the tissue free water(TFWT) and the organically bound tritium(OBT) were measured. The measured concentrations were agreed well with model predictions.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.355-356
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• 2022

The pilot GOBT program was carried out from November 17th - December 17th 2021 at KIMFT; self-isolation for 10 days, Basic Safety Training(BST) for 5 days and 2 weeks of on-board training(OBT) were conducted during the period. Total 20 cadets from 5 different Countries were participated under the financial support of IMO ITCP and Korean ODA program. The program aims to provide capacity-building courses focusing on on-board training and assisting future maritime officers in meeting the minimum standard of seagoing experience in accordance with the STCW Convention. In the meantime, the program itself can serve as a platform to share best practices of how the training including the curriculum can be organized on specialized training vessels. The questionnaire survey was carried out to evaluate the GOBT program, and the overall average score was 96.4 points which seems that the cadets were very satisfied with the Global On-Board Training program provided by KIMFT in 2021.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.10
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• pp.1509-1516
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• 2004

During fuel irradiation tests, all parts of cylindrical structure with multiple holes act as heat sources due to fussion heat and ${\gamma}$-flux. The high temperature is especially generated in the center of pellet. Because of the high temperature, many problems occur, such as melting of pellet and declining of heat transfer between cladding and coolant. In this paper, it is attempted to minimize the temperature of pellet using optimization method. For thermal and optimization analysis of structure, the finite element method code, ANSYS 5.7 is used. Through the optimum design process, the temperature of SBT diminished 10％ and the temperature of OBT diminished 18％.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2682-2684
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• 1999

This paper presents design and stability analysis of the constant frequency Flyback type converter using average current-mode control. The average current-mode control has been recently reported, and superior characteristics over a peak current-mode control such as a good tracking performance of an average current, no slope compensation and noise immunity. By the improvement of PM(Phase Margin) obt from applying the compensator in the current loop, the stability of designed flyback convert more improved. The validity of designed convert confirmed by simulation and experimental result

• East Asian mathematical journal
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• v.39 no.2
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• pp.229-250
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• 2023

The purpose of this study is to investigate the impact of project learning using chatbots on artificial intelligence literacy. The subjects of the study were a total of 41 students from 1st to 3rd grade of general high school in Gyeonggi-do. Classes were held after school for a total of 6 hours, and the contents of the classes consisted of the concept and characteristics of artificial intelligence, the concept and expression of knowledge, OBT application for Kakao i open builder, guidance on how to create chatbots, and chatbot production practice. As a result of the pre- and post-test of the experimental group, the quantitative value of artificial intelligence literacy increased in all three grades. In the case of second-year students who set up a comparison group, when compared with the results of the comparison group, there was a significant positive effect on the AI literacy result, and female students were found to be more effective than male students.

• KSBB Journal
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• v.17 no.3
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• pp.295-301
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• 2002

The effects of nonionic surfactant (SPAN 20) on the desulfurization process by Rhodococcus sp. strain IGTS8 have been investigated at various oil/water ratios, pHs and concentrations of surfactant. The hexadecane containing DBT was employed as model oil. The presence of surfactant in the oil/water mixture stabilized the oil/water interface, thus enhanced the efficiency of desulfurization. The volume percentages of oil in the oil/water mixture were 30, 50 and 70%. The concentrations of surfactant were varied from 0 to 0.33 wt% relative to water phase. In general, the biodesulfurization efficiencies were decreased as the concentration of SPAN 20 and the volume percentage of oil phase increased.

• Magazine of the Korean Society of Agricultural Engineers
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• v.24 no.1
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• pp.53-62
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• 1982

This study was attempted to find best fitted distribution and the equations for probable maximum flow with the evaluation of parameters by the method of moment for the rat- ional design of hydraulic structures in the annual exceedance series. Six subwatersheds were selected as studying basins along Geum River basin. The results obtained through this study were analyzed and summarized as follows. 1. Fitted probability distribution was showed in the order of Three Parameter Lognorm al, Type 1 Extremal, Exponential, Pearson Type III, and Log Pearson Type I distribu- tion as the results of x$^2$ goodness of fit test. 2. Kolmogorov-Smirnov test showed in the order of Three Parameter Lognormal, Exp- onential' Pearson Type III, Log Pearson Type III and Type 1 Extremal distribution for the fitted probability distribution. 3. It can be concluded that Three parameter Lognormal distribution is a best fitted one among some other distributions out of respect for each both tests. An Exponential distribution was proposed as a suitable one by Chow, V.T. showeci lower fittness than that of Three Parameter Lognormal in Geum River basin. 5. Probable flood flow equations followins the return periods for each station were obt- ained by Three Parameter Lognormal distribution. 6. It is urgently essential that best fitted probability distribution should be established for the annual exceedance series in the main river systems of Korea.

• Textile Coloration and Finishing
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• v.3 no.1
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• pp.17-24
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• 1991

Polyesteramide(PEA) has been synthesized with different molar ratio of 6-aminocaproic acid(ACA) and oligo butylene terephthalate(OBT) prepared from Dimethyl terephthalate(DMT) and 1, 4-butanediol(BD) by the melt polymerization. Oligomer and polymer molecular structure were characterized by IR spectra, H'-NMR spectra. Also the thermal properties were examined by thermogravimetric analysis(TGA) and differential scanning calorimetry(DSC). DSC and TGA results exhibited that the$ T_m$ s were detectable in the vicinity of $170-220^{\circ}C$ and the Ta's were detectable in the vicinity of $380-390^{\circ}C$ . X-ray diffraction analysis results show that the synthesized polyesteramide has high degree of crystallinity.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.109-116
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• 2004

In a satellite time management system, the GPS-based clock synchronization technique[1] has the merits of precision time management by knowing the time difference or the error between the OBT(On Board Time) of the internal processors and GPS time every second. It can be realized employing the DPLL(Digital Phase Loop Lock) and FEP(Front End Processor) circuitry for the clock synchronization[2]. In this paper, a refined DPLL & FEP scheme is proposed to provide the precision, stability and robustness of the operation, which is to compensate the errors and noise of the GPS signal, and also to cope with the case when the GPS signal is lost due to several reasons. The simulation and HIL (Hardware In the Loop) test results using the FM(Flight Model) in the course of KOMPSAT-2(Korea Multi Purpose Satellite-2) design and development are illustrated to demonstrate the salient features of this methodology.

• Journal of Radiation Protection and Research
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• v.23 no.2
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• pp.75-82
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• 1998

Tritium concentration in the atmosphere during HTO exposure was different between two experiments due to different velocity of HTO evaporation. Assimilation rate of the rice plant was considered to be higher than that of Chinese cabbage The uptake of atmospheric HTO into tissue free water tritium(TFWT) was higher in rice plants than in Chinese cabbage. However, organically bound tritium(OBT) concentration is relatively higher in Chinese cabbage than in rice. The specific activity ratio(SAR) increased slowly after HTO exposure and decreased gradually with time. The behaviour of HTO in the soil was affected by the environmental conditions.