• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.19-26
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• 2024

In this study, the electrochemical properties of SiOx@C composite materials were prepared to alleviate volume expansion and cycle stability of silicon and to increase the capacity of anode material for LIBs. SiO₂ particles of 100, 200, and 500 nm were synthesized by the Stӧber method, and reduced to SiOx (0≤x≤2) through the magnesiothermic reduction method. Then, SiOx@C anode materials were synthesized by carbonization of PVC on SiOx. The physical properties of prepared SiOx and SiOx@C anode materials were analyzed by XRD, SEM, TGA, Raman spectroscopy, XPS and BET. The electrochemical properties were investigated by cycling performance, rate performance, CV and EIS test. As a result, the SiOx@C-7030 manufactured by coating carbon at SiOx : C = 70 : 30 on a 100 nm SiOx with the smallest particle size showed the best electrochemical properties with a discharge capacity of 1055 mAh/g and a capacity retention rate of 81.9% at 100 cycles. It was confirmed that cycle stability was impoved by reducing particle size and carbon coating.

• Journal of the Korea Society of Computer and Information
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• v.29 no.4
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• pp.115-123
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• 2024

In this paper, we propose a vibration notification system that combines navigation information and wearable bands to ensure safe driving for the transportation vulnerable. This system transmits navigation driving information to a linked application, converts it into a vibration signal, and provides notifications through a wearable band. Existing navigation systems focus on providing route guidance and location information, so the driver's concentration is dispersed, and safety and convenience are deteriorated, especially for those with mobility impairments, due to standard vision and delayed recognition of stimuli, resulting in an increasingly high traffic accident rate. To solve this problem, navigation driving information is converted into vibration signals through a linked application, and vibration notifications for events, left turns, right turns, and speeding are provided through a wearable band to ensure driver safety and convenience. In the future, we will use cameras and vehicle sensors to increase awareness of safety inside and outside the vehicle by adding a function that provides notifications with vibration and LED when the vehicle approaches or recognizes an object, and we will continue to conduct research to build a safer driving environment. plan.

• Journal of the Mineralogical Society of Korea
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• v.21 no.2
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• pp.139-159
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• 2008

Geochemical analysis of the various kinds of water including observation borehole groundwater was carried out for the assessment of the hydrological safety of the underground oil storage cavern and the potentiality of mineralogical and microbiological clogging was estimated. Most of water samples belonged to $Ca-HCO_3$ and $Ca-HCO_3-SO_4$ types. There was no distinct chemical difference in the various kinds of water. All kinds of water are undersaturated with the calcite which is the major clogging mineral. Most water samples have low Fe and Mn concentrations. However, they are saturated or oversaturated with the iron-oxide/hydroxide minerals and have high dissolved oxygen contents which suggests the possibility of clogging by the iron-oxide/hydroxide minerals as a long-term aspect. Several water samples from the ground observation borehole also show the high saturation indices far the clay minerals, which can fill up the fractures, indicating the possibility of clogging by the clay minerals. Statistical analysis shows the degree of mineral precipitation or dissolution is mainly controlled by pH, Eh and DO of water samples. According to the microbial analysis, the aerobic microbes and slime forming bacteria are dominant in most water samples and anaerobic microbes including sulfate reducing bacteria are very low or not detected. Although the slime forming bacteria which are known as a main microbial cause of the clogging is lower than $10^5\;CFUs/mL$ in all water samples, because the slime forming bacteria are dominant microbe in several observation boreholes, the clogging can be caused by it as a long-term aspect. In addition, the possibility of clogging can be increased if the microbial effect is combined with the mineralogical effect such as iron oxide/hydroxide minerals for the possibility of clogging. Therefore, the systematic and long-term program for the assessment of clogging is required for the safe operation of underground oil storage cavern.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.4
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• pp.181-186
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• 2011

Thermal stability of the $TiO_2$ SCR catalyst with W03 loading was investigated in terms of structural and morphological analyses. The $TiO_2$ catalysts with 10 w% $WO_3$ content and without $WO_3$ were prepared. which were heat-treated at $800^{\circ}C$ for 5 h. It was found that the catalytic acidity was decreased by thermal degradation in the $WO_3-TiO_2$ specimen that relatively less than the $TiO_2$ specimen from FT-IR analysis. The phase transition of the $TiO_2$ catalyst from anatase to rutile was increased by heal-treatment, and the percentage of the rutile phase was 28.4 % in the $WO_3-TiO_2$ and 22.9 % in the $TiO_2$. A shell region of $WO_3$ distinguished from a $TiO_2$ particle was also observed in the grain boundary region, and the $WO_3$ led to the suppression of grain growth. It could be confirmed that the suppression of grain growth can contribute to the improvement of catalytic properties for thermal stability more than the increase of anatase-rutile phase transformation which cause the reduction of the catalytic activity in the $TiO_2$ SCR catalyst by the presence of $WO_3$.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.4
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• pp.307-327
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• 2008

Geochemical study on the rocks and minerals of the Gyeongju low and intermediate level waste repository was carried out in order to provide geochemical data for the safety assessment and geochemical modeling. Polarized microscopy, X-ray diffraction method, chemical analysis for the major and trace elements, scanning electron microscopy(SEM), and stable isotope analysis were applied. Fracture zones are locally developed with various degrees of alteration in the study area. The study area is mainly composed of granodiorite and diorite and their relation is gradational in the field. However, they could be easily distinguished by their chemical property. The granodiorite showed higher $SiO_2$ content and lower MgO and $Fe_2O_3$ contents than the diorite. Variation trends of the major elements of the granodiorite and diorite were plotted on the same line according to the increase of $SiO_2$ content suggesting that they were differentiated from the same magma. Spatial distribution of the various elements showed that the diorite region had lower $SiO_2,\;Al_2O_3,\;Na_2O\;and\;K_2O$ contents, and higher CaO, $Fe_2O_3$ contents than the granodiorite region. Especially, because the differences in the CaO and $Na_2O$ distribution were most distinct and their trends were reciprocal, the chemical variation of the plagioclase of the granitic rocks was the main parameter of the chemical variation of the host rocks in the study area. Identified fracture-filling minerals from the drill core were montmorillonite, zeolite minerals, chlorite, illite, calcite and pyrite. Especially pyrite and laumontite, which are known as indicating minerals of hydrothermal alteration, were widely distributed in the study area indicating that the study area was affected by mineralization and/or hydrothermal alteration. Sulfur isotope analysis for the pyrite and oxygen-hydrogen stable isotope analysis for the clay minerals indicated that they were originated from the magma. Therefore, it is considered that the fracture-filling minerals from the study area were affected by the hydrothermal solution as well as the simply water-rock interaction.

• Economic and Environmental Geology
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• v.28 no.3
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• pp.185-197
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• 1995

Tungsten skarns in the Chungju mine which consists mainly of strata-bound type iron ore deposits are found in the vicinity of the contact between the age-unknown Kyemeongsan Formation and granitic rock intrusions of Mesozoic age($134{\pm}2Ma$). Tungsten skarns were formed extensively from alumina and silica-rich schistose rocks by the introduction of calcium and iron from hydrothermal solution. The skarns comprise a metasomatic column and are subdivided into four facies; garnet facies, wollastonite facies, epidote facies and chlorite facies. The skarn process in time-evolutional trend can be divided broadly into the four facies in terms of the paragenetic sequence of calc-silicates and their chemical composition. Skarn and ore minerals were formed in the following sequence; (1) garnet facies, adjacent to biotite granite, containing mainly garnet(>Ad96) and magnetite, (2) wollastonite facies containing mainly wollastonite and garnet(Ad95~60), (3) epidote facies, containing mainly epidote(Ps35~31), quartz, andradite-grossular(Ad63~50), and scheelite, (4) chlorite facies, adjacent to and replacing schist, containing mainly chrolite, muscovite, quartz, calcite, epidote(Ps31~25), hematite and sulfides. The mineral assemblage and mineral compositions. suggest that the chemical potentials of Ca and Fe increased toward the granitic rock, and the component Al, Mg, K, and Si decreased from the host rock to granitic rock. The homogenization temperature and salinity of fluid inclusion in scheelite, quartz and epidote of epidote facies skarn is $300-400^{\circ}C$ and 3-8wt.% eqiv. NaCl, respectively. ${\delta}^{34}S$ values of pyrite and galena associated with chlorite facies skarn is $9.13{\sim}9.51%_{\circ}$ and $5.85{\sim}5.96%_{\circ}$, respectively. The temperature obtained from isotopic com· position of coexisting pyrite-galena is $283{\pm}20^{\circ}C$. Mineral assemblages and fluid inclusion data indicate that skarn formed at low $X_{CO_2}$, approximately 0.01. Temperature of the skarn mineralization are estimated to be in the range of $400^{\circ}C$ to $260^{\circ}C$ and pressure to be 0.5 kbar. The oxygen fugacity($fo_2$) of the skarn mineralization decreased with time. The early skarn facies would have formed at log $fo_2$ values of about -25 to -27, and late skarn facies would have formed at log $fo_2$ values of -28 to -30. The estimated physicochemical condition during skarn formation suggests that the principal causes of scheelite mineralization are reduction of the ore·forming fluid and a decrease in temperature.

• Korean Journal of Child Education & Care
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• v.18 no.2
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• pp.85-102
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• 2018

The purpose of this study is to determine the working conditions and demands of the assistant workforce at childcare centers, and to provide suggestions on policies for childcare teachers. To achieve the purpose of the study, a total of 190 assistant teachers, nursing helpers, alternative teachers and others were surveyed online during the month of August 2017. The survey examined the employment route and working motives, working conditions and environment, job and educational difficulties for analyzing the work conditions and demands of ancillary staff. For the analysis method, SPSS 12.0 was used to analyze frequency and difference. The main findings are as follows. First, childcare center assistants were able to work at their respective times, making it mandatory for them to enter the workforce, and making job openings for ancillary teachers. Second, 73.7% said the daily working hours were '4 hours to 8 hours' under the conditions and 57.9% said 'More than 510,000 won to less than 1 million won.' Average amount of rest time per day was about 30 minutes, and 17% had no rest periods. Third, based on the job and education status, ancillary personnel performed "infant and child guidance and interaction", "Cleaning and cleanliness related tasks" most actively, and "care for cleaning and cleanliness" and "care for morning and night care". Fourth, in the job trouble and difficulty, ancillary staff found it difficult to satisfy with wage related complaints and job insecurity, and the reason for agreeing to the non-regular workforce becoming a regular worker was found to be due to the stability of employment. Lastly, the most urgent tasks to solve the problem of non-regular workers were to fill the wage gap between regular and irregular workers, shorten the working hours and improve the working conditions. The policy implications are presented based on the above findings.

• Journal of the Korean Electrochemical Society
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• v.22 no.1
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• pp.36-42
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• 2019

A macroporous Sn thick film as a high capacity negative electrode for a lithium ion secondary battery was prepared by using a chemical etching method using nitric acid for a Sn film having a thickness of $52{\mu}m$. The porous Sn thick film greatly reduced the over-voltage for the alloying reaction with lithium by the increased reaction area. At the same time. The porous structure of active Sn film plays a part in the buffer and reduces the damage by the volume change during cycles. Since the porous Sn thick film electrode does not require the use of the binder and the conductive carbon black, it has substantially larger energy density. As the concentration of nitric acid in etching solution increased, the degree of the etching increased. The etching of the Sn film effectively proceeded with nitric acid of 3 M concentration or more. The porous Sn film could not be recovered because the most of Sn was eluted within 60 seconds by the rapid etching rate in the 5 M nitric acid. In the case of etching with 4 M nitric acid for 60 seconds, the appropriate porous Sn film was formed with 48.9% of weight loss and 40.3% of thickness change during chemical acid etching process. As the degree of etching of Sn film increased, the electrochemical activity and the reversible capacity for the lithium storage of the Sn film electrode were increased. The highest reversible specific capacity of 650 mAh/g was achieved at the etching condition with 4 M nitric acid. The porous Sn film electrode showed better cycle performance than the conventional electrode using a Sn powder.

• Korean Journal of Labor Studies
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• v.24 no.2
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• pp.95-136
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• 2018

As the number of precariats grows, their poor labor rights and working conditions are becoming issues of major concern all over the world but how to represent their interests is still controversial. Basically, the union is the institutional mechanism for representing the labor rights. However, it is difficult for workplaceand enterprise-based unions to fully represent the labor rights of precarious workers. Recently, so-called community unions have emerged in the United States, the United Kingdom, and Japan as independent organizations representing the rights of non-standard workers. Community unions refer to labor unions which organize precarious workers across firms at the regional level. They are known to be suitable for covering the unemployed, job seekers, indirect employment workers, short-term contract workers, and small-firm workers. In South Korea, since the financial crisis in 1997, a dramatic increase in the number of precariats leads to emergence of new types of trade unions such as the Youth Community Union, the Arbeit Workers' Union, the Artist Social Union and the Korea Musician's Union. They have engaged in various activities to guarantee the labor rights of precariats. Recently, researchers have also tried to identify defining characteristics of these new forms of unionism. To expand research on trade unionism in South Korea, this study compares two different types of community unions: the Youth Community Union and the Arbeit Workers' Union. We believe that this attempt can contribute to the research on the alternative labor movement. For this purpose, this study starts with theoretical discussions on community unions, and compares the Youth Community Union with the Arbeit Workers' Union based on the five characteristics of community unionism: membership and organization structure, the recognition struggle, the type or scope of interest, solidarity with other civic organizations, and the repertoire of resistance strategies. Based on this comparative analysis, this study seeks to foresee the possibility of how community unionism will develop in South Korean in the future.

• Journal of Korea Entertainment Industry Association
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• v.15 no.4
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• pp.167-186
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• 2021

The purpose of this study was to present a new direction for sports talent cultivation, determine the sports talent cultivation status in various types of sports and relevant areas, and present specific plans for activating practical sports talent cultivation in the elderly population in an effort to cope with the rapid changes of times. For this purpose, literature review was performed to analyze the elderly sports and sports talent cultivation status, analyze the problems with elderly sports and sports talent cultivation and development tasks, and present the following comprehensive plan for cultivating elderly sports talent cultivation in pursuit of elderly sports promotion: First, it is necessary to become more competitive in education by developing various programs for convergent and combined elderly sports talent cultivation as well as by changing into a convergent and combined way of thinking in the organizational culture environment of sports. Second, it is necessary to build more career education infrastructures for elderly sports talent cultivation in the elderly sports and relevant departments. Career education may become an issue in every area, which means building comprehensive DBs for undergraduates and graduates. Third, it is necessary to give greater support to research and development in the entire area of elderly sports. This means implementing relevant projects efficiently through governance with the Ministry of Culture, Sports, and Tourism in charge of elderly sports policies, the Ministry of Health and Welfare, and professionals in the private sectors. Fourth, it is necessary to make comprehensive, systematic, and mid- and long-term strategies for cultivating sports talent at the governmental level. This means sports talent cultivation and search, career and employment, reeducation (competence reinforcement training), and job and employment stability in the areas of education, health, and welfare as well as sports. Fifth, it is necessary to operate a tentatively-called elderly health agency under the influence of the Office of the Prime Minister. This requires expansion and qualitative improvement of education on the basis of greater efficiency in preventing any overlapped task from wasting the budget through inter-department cooperation and positive partnership.