• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.9
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• pp.733-738
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• 1998

본 논문에서는 고체 리듐 전지를 개발하기 위하여 poly(ethylene oxide) [PEO] 에 $LiClO_4$, poly (vinylidene fluoride) [PVDF] 및 가소제로 propylene carbonate [PC] 와 ethylene carbonate[EC] 등을 혼합여 고분자 저해질을 제조하였다. 또한 고체 리듐 전지용 정극으로써 우수한 특성이 기대되는 $Li_xV_3O_8$을 졸-겔법에 의해 합성하여 $Li_xV_3O_8$SPE/Li cell 의 전기화학적 특성을 측정하였다. 고분자 matrix는 PEO와 PVDE를 혼합 사용한 결과 $PEO_4 PVDF_4LiCIO_4PC_5EC_5$ 고분자 전해질이 상온에서 $5.2 {\times} 10{-3}$ S/cm 의 높은 이온 전도도를 나타냈으며 리듐 이온 transference number는 0.3이었다. 졸-겔법에 의해 제조된 $Li_xV_3O_8$을 사용한 $Li_xV_3O_8$SPE/Li cell의 방전시 cell 저항이 방전 초기에는 비소한 증가를 하다가 방전 말기 전압인 2.0V에서 크게 증가하였다. $Li_xV_3O_8$ composite 정극의 첫 번째 방전 용량은 295㎃h/g이었으며 8번째 충방전 싸이클부터 방전 용량이 안정화 되었고 15번째 방전 용량도 212㎃h/g으로 고체 전지용 정극으로써 우수한 특성을 보였다.

• Corrosion Science and Technology
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• v.19 no.1
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• pp.31-36
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• 2020

An efficient wet process approach to modifying natural graphite (NG) electrodes for Li-ion batteries is introduced in this paper. With homogeneous mixing and thermal decomposition of NG with diammonium phosphate ((NH₄)₂HPO₄), phosphorus and nitrogen were successfully incorporated into the surface layer of NG particles. Electron microscopy and X-ray photoelectron spectroscopy analyses demonstrated that the surface was well modified by this process. As a result, the treated NG electrodes exhibited much improved electrochemical performance over pristine NG at two different temperatures: 25 ℃ and 50 ℃. Excellent capacity retention of 95.6% was obtained after 100 cycles at 50 ℃. These enhanced properties were confirmed in a morphology analysis on the cross-sections of the NG electrodes after galvanostatic cycling. The improved cycle and thermal stabilities can be attributed to the surface treatment with phosphorus and nitrogen; the treatment formed a stable solid electrolyte interphase layer that performed well when undergoing Li insertion and extraction cycling.

• Steel and Composite Structures
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• v.24 no.4
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• pp.409-423
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• 2017

This paper presents an experimental study on damage evolution laws of solid-web steel reinforced concrete (SRC) T-shaped columns along the direction of the web under various loadings. Ten specimens with a scale ratio of 1/2 and a shear span ratio of 2.5 were designed and fabricated. The influences of various parameters, including the axial compression ratio, steel ratio, and loading mode, were examined. The mechanical performances including load-displacement curve and energy dissipation capacity under the monotonic and low cyclic loadings were analyzed. Compared with the monotonic loading, bearing capacity, ultimate deformation capacity, and energy dissipation capacity of the specimens decrease to some extent with the increase of the displacement amplitude and the number of loading cycle. The results show that the damage process of the SRC T-shaped column can be divided into five stages, namely non-damage, slight-damage, steadily-developing-damage, severe-damage and complete-damage. Finally, based on the Park-Ang model, a modified nonlinear damage model which combines the maximum deformation with hysteretic energy dissipation is proposed by taking into account the dynamic influence of the aforementioned parameters. The results show that the modified model in this paper is more accurate than Park-Ang model and can better describe the damage evolution of SRC T-shaped columns.

• Journal of the Korean Home Economics Association
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• v.34 no.5
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• pp.183-196
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• 1996

The purposes of this study were to review the effects of textiles production on the environment, and to investigate the environmental consciousness and environmental preservation behavior of textile producers. This study was conducted by reference analysis and empirical research. To develope theoretical framework of dimensions of environmental behavior, references concerned were analyzed. And for empirical study, researcher developed a questionnaire based on the free writing by producers and references. The questionnaire included problems about environmental consciousness, environmental behavior, demographic variables, and environmental variables. 135 questionnaires were used for final data analysis. ANOVA and factor analysis were used. The results were as follows: First, the level of global environmental problem consciousness was relatively high. The conscious level of water pollution caused by the waste water from textile mills was the highest, and that of desertation of mountain caused by timber cutting was the lowest. The effects of textile dyers and finishers on the environment were the highest, and that of designers were the lowest. Second, the results of reference analysis showed that the dimensions of textile producers environmental behavior were resource and energy saving, solid waste reduction, and green product production. And the results of empirical study were resource and energy saving, resource reuse or recycling, solid waste reduction, and green product production, and total variances was 62.3%. The practice was the lowest. Third, global environment problem consciousness, environment problem consciousness caused by the textile life-cycle concerned, and clothing seperate-collection or not at residing place were effective on environmental behavior, and 52.45% of environmental behavior was explained with above variables.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.569-581
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• 2020

Since the dehydration packages of offshore plant deal directly with oil & gas, there is a great risk of fire and explosion during operation. Therefore, this study performed risk assessment through HAZard & OPerability (HAZOP) for solid desiccant dehydration package that can remove water component of natural gas in offshore floating liquefied natural gas (LNG) production facilities below 0.1 ppmv. The risk matrix was determined by dividing the likelihood and the severity into five levels separately by asset, life, environment and reputation. The piping & instrumentation diagram (P&ID) of the dehydration package was divided into 9 nodes. Total 22 deviations were assessed in consideration of the adsorption and desorption conversion cycle. A risk assessment based on deviations revealed 14 major hazards. Three representative types of hazards were open/close failure of the control valve, control failure of the heater, and abnormal operation of the regeneration gas cooler. Finally, we proposed the installation of additional safety devices to improve safety against these major hazards, such as safety instrumented functions, alarms, etc.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.1
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• pp.9-27
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• 2021

As an example of research activities in decontamination for decommissioning, new data are presented on the options for corrosion layer dissolution during the decommissioning decontamination, or persulfate regeneration for decontamination solutions re-use. For the management of spent decontamination solutions, new method based on solvent extraction of radionuclides into ionic liquid followed by electrodeposition of the radionuclides has been developed. Fields of applications of composite inorganic-organic absorbers or solid extractants with polyacrylonitrile (PAN) binding matrix for the treatment of liquid radioactive waste are reviewed; a method for americium separation from the boric acid containing NPP evaporator concentrates based on the TODGA-PAN material is discussed in more detail. Performance of a model of radionuclide transport, developed and implemented within the GoldSim programming environment, for the safety studies of the LLW/ILW repository is demonstrated on the specific case of the Richard repository (Czech Republic). Continuation and even broadening of these activities are expected in connection with the approaching end of the lifespan of the first blocks of the Czech NPPs.

• Journal of Electrochemical Science and Technology
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• v.12 no.4
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• pp.398-405
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• 2021

To fabricate a full-scale pilot model of the cost-effective Na-(Ni,Fe)Cl₂ cell, a Na-beta-alumina solid electrolyte (BASE) was developed by applying a one-step synthesis cum sintering process as an alternative to the conventional solid-state reaction process. Also, Fe metal powder, which is cheaper than Ni, was mixed with Ni metal powder, and was used for cathode material to reduce the cost of raw material. As a result, we then developed a prototype Na-(Ni,Fe)Cl₂ cell. Consequently, the Ni content in the Na-(Ni,Fe)Cl₂ cell is decreased to approximately (20 to 50) wt.%. The #1 prototype cell (dimensions: 34 mm × 34 mm × 235 mm) showed a cell capacity of 15.9 Ah, and 160.3 mAh g^-1 (per the Ni-Fe composite), while the #2 prototype cell (dimensions: 50 mm × 50 mm × 335 mm) showed a cell capacity of 49.4 Ah, and 153.2 mAh g^-1 at the 2^nd cycle.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.3
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• pp.397-410
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• 2023

This study examined the efficacy of various chlorinating agents in partitioning light water reactor spent fuel, with the aim of optimizing the chlorination process. Through thermodynamic equilibrium calculations, we assessed the outcomes of employing MgCl₂, NH₄Cl, and Cl₂ as chlorinating agents. A comparison was drawn between using a single agent and a sequential approach involving all three agents (MgCl₂, NH₄Cl, and Cl₂). Following heat treatment, the utilization of MgCl₂ as the sole chlorinating agent resulted in a moderate separation. Specifically, this method yielded a solid separation with 96.9% mass retention, 31.7% radioactivity, and 44.2% decay heat, relative to the initial spent fuel. In contrast, the sequential application of the chlorinating agents following heat treatment led to a final solid separation characterized by 93.1% mass retention, 5.1% radioactivity, and 15.4% decay heat, relative to the original spent fuel. The findings underscore the potential effectiveness of a sequential chlorination strategy for partitioning spent fuel. This approach holds promise as a standalone technique or as a complementary process alongside other partitioning processes such as pyroprocessing. Overall, our findings contribute to the advancement of spent fuel management strategies.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.2
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• pp.85-93
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• 2013

This study has been carried out to elucidate the characteristics of the dissolution for Thermal Decomposed Solid Waste of uranium-bearing sludge (TDSW), the removal of impurities by an alkalization in a nitric acid dissolving solution of TDSW, and the selective removal (/recovery) of uranium by an acidification in an carbonate alkali solution, respectively. TDSW generated by thermal decomposition of U-bearing sludge which was produced in the uranium conversion plant operation, was stored in KAERI as a solid-powder type. It is found that the dissolution of TDSW is more effective in nitric acid dissolution than oxidative-dissolution with carbonate. At 1 M nitric acid solution, TDSW was undissolved about 30wt% as a solid residue, and uranium contained in TDSW was dissolved more than 99%. In order to the alkalization for the nitric acid dissolving solution of TDSW, carbonate alkalization is more effective with respect to remove the impurities. At the carbonate alkali solution controlled to about 9 of pH, Al, Ca, Fe and Zn co-dissolved with U in dissolution step was removed about $98{\pm}1%$. On the other hand, U could be recovered more than 99% by an acidification at pH about 3 in a carbonate alkali solution, which was nearly removed the impurities, adding 0.5M $H_2O_2$. It was found that uranium could be selectively recovered (/removed) from TDSW.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1267-1269
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• 2010

The pure crystalline $Li_{1.1}V_{0.9}O_2$ powder has been prepared by a simple solid state reaction of $Li_2CO_3$ and $V_2O_3$ precursors under nitrogen gas containing 10 mol % hydrogen gas flow. The structure of $Li_{1.1}V_{0.9}O_2$ powder was analyzed using Xray diffraction (XRD) and scanning electron microscope (SEM). The stoichiometric $Li_{1.1}V_{0.9}O_2$ powder was used as anode active material for lithium secondary batteries. Its electrochemical properties were investigated by cyclic voltammetry and constant current methods using lithium foil electrode. The observed specific discharge capacity and charge capacity were 360 mAh/g and 260 mAh/g during the first cycle, respectively. In addition, the cyclic efficiency of this cell was 72.2% in the first cycle. The specific capacity of $Li_{1.1}V_{0.9}O_2$ anode rapidly declines as the current rate increases and retains only 30 % of the capacity of 0.1C rate at 1C rate. The crystallinity of the $Li_{1.1}V_{0.9}O_2$ anode decrease as discharge reaction proceeds. However, the relative intensity of main peaks was almost recovered when the cell was charged up to 1.5 V.