• Journal of Industrial Convergence
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• v.22 no.5
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• pp.39-48
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• 2024

Due to COVID-19, much research has been conducted on learning loss and educational gaps due to the postponement of the start of school and prolonged online distance learning, and most of the research has focused on the phenomenon of educational gaps. If a pandemic situation like this occurs in the future, fundamental policies are needed to resolve the educational gap. A fundamental solution requires not only an understanding of the educational gap phenomenon, but also the structure behind the phenomenon. Therefore, from a structuralist perspective, this study sought to model the educational gap caused by COVID-19 as a prototype of systems thinking and identify its structure. In addition, we looked at the unintended consequences resulting from policies aimed at resolving existing educational gaps. In order to respond to similar disaster situations in the future, policies for resolving the digital gap, support for basic academic skills, quality improvement for distance learning, and self-directed learning were discussed based on the structure of this study.

• Journal of the Korean Electrochemical Society
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• v.2 no.2
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• pp.88-92
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• 1999

The apparent density. self-separation of the electrode composite from current collector in the electrolyte solution and specific resistance of electronic conduction of the electrode composite were examined by the variation of content of conductive material such as graphitic and black carbons in $LiCoO_2$ composite electrode for lithium ion battery. Increasing the content of conductive material, the apparent density of Lico02 composite electrode was decreased and that of $LiCoO_2$ in composite electrode was only rapidly decreased compared to that of composite. $LiCoO_2$ composite electrodes containing more than 4.1 weight percent of super s black as a conductive material were seU-separated by the immersion into 1 mol/I $LiPF_6$ in propylene carbonate and diethyl carbonate (1:1 volume ratio). Specific resistances related to the electronic conduction of composite electrode were decreased by the increasing the content i)f conductive material. Specific resistance of the composite electrode including $2\~3\%w/w$ of super s black as conductive material was similar to that of $12\%w/w$ of Lonza KS6. In the range of this study, super s black as conductive material is better than Lonza KS6 on battery capacity because of apparent density of $LiCoO_2$ in electrode composite including super s black is higher than that of Lonza KS6.

• Journal of Veterinary Clinics
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• v.22 no.4
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• pp.322-327
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• 2005

DLA class I complement-dependent cytotoxicity (CDC) cross-match method was established to control hyperacute rejections in organ transplantation. The aim of the present study is to investigate if DLA class 1 CDC corssmatch method is effective to prevent hyperacute rejections in canine renal allografts. Seven mongrel dogs of similar age and weight were used. Erythrocyte crossmatch was first performed and only the negatives were used. Among the same blood types, CDC cross-match was performed. Anti-dog serum, Hank's balanced salt solution(HBSS), and tile self-serum was used as a positive-, a negative-, and all auto-control respectively. After the reaction with class I complement, it was stained with eosin and scored by international cytotoxicity scoring system under inverted phase microscope. According to these results, kidneys oi CDC negatives among same blood types were cross-transplanted to observe the incidence of hyperacute rejections. One of four 1.2 B blood type dogs had autoantibodies. here were negative CDC results among each blood type, and also there were negative results between different blood types. Two pairs with the same blood types and negative CDC results underwent allo-transplantation each other. There were no hyperacute rejections. DLA cross-match method studied in this experiment for canine renal allograft can be effective to prevent hyperacute rejections. it may be applicable for the future studies of histocompatibility testing in canine renal allografts.

• Journal of agricultural medicine and community health
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• v.35 no.3
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• pp.314-325
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• 2010

Objectives: The purpose of this study was to investigate the effects of pet dog-assisted activities on self-esteem, depression and cognitive function of elderly people Method: The experimental group(pet dog-assisted group) consisted of 22 people over 65 years old out of about 90 elderly people registered with a home for the aged and the control group(non-pet dog assisted group) consisted of 22 people over 65 years old out of about 90 elderly people registered with another home for the aged in Daegu. Both groups had similar general characteristics, state of health, conduct on health and self-esteem, depression and cognitive abilities. Nineteen people who participated in the program at least 10 times out of 12, were chosen for the final analysis from the experimental group. For the control group, 20 people who responded to all three tests, which had been conducted before, 1 week after, and four week after the experiment, were analyzed. Result: Mean(${\pm}SD$) differences between before and 1 week after the experiment for self-esteem, depression, and cognitive function were 5.84(${\pm}3.06$), -3.26(${\pm}1.76$), 1.47(${\pm}1.26$), respectively. Those between before the experiment and 4 weeks after the experiment was 5.68(${\pm}3.64$), -3.94(${\pm}2.32$), 1.63(${\pm}0.96$), respectively. Those for control group between before and after the experiment were -0.40(${\pm}1.27$), 0.00(${\pm}0.92$), 0.15(${\pm}0.93$), respectively. Those for control group between before and 4 weeks after the experiment were -0.45(${\pm}2.24$), 0.25(${\pm}1.68$), 0.15(${\pm}0.93$), respectively. All the differences between experiment and control group in mean differences between before and 1 week after experiment, between before and 4 weeks after experiment were statistically significant(p<0.05). Conclusion: This study suggests that the pet-assisted activities can be useful solution for elderly people who have psychological and emotional problems caused by retrogression of physical, mental and social ability.

• Journal of the Korean Electrochemical Society
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• v.19 no.1
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• pp.21-27
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• 2016

Vanadium redox flow batteries (VRFBs) using the electrolytes containing various vanadium ions in sulfuric acid as supporting solution are one of the energy storage devices in alternatively charging and discharging operation modes. The positive electrolyte contains $V^{5+}/V^{4+}$ and the negative electrolyte $V^{2+}/V^{3+}$ depending on the operation mode. To prevent the mixing of two solutions, proton exchange membranes are mainly used in VRFBs. Nafion 117 could be the most promising candidate due to the strong oxidative property of $V^{5+}$ ion, but causes high crossover of electroactive species to result in a decrease in coulombic efficiency. In this study, the composite membranes using Nafion ionomer and porous polyethylene substrate were prepared to keep good chemical stability and to decrease the cost of membranes, and were compared to the properties and performance of the commercially available electrolyte membrane, Nafion 117. As a result, the water uptake and ionic conductivity of the composite membranes increased as the thickness of the composite membranes increased, but those of Nafion 117 slightly decreased. The permeability of vanadium ions for the composite membranes significantly decreased compared to that for Nafion 117. In a single cell test for the composite membranes, the voltage efficiency decreased and the coulombic efficiency increased, finally resulting in the similar energy efficiency. In conclusion, the less cost of the composite membranes by decreasing 6.4 wt.% of the amount of perfluorinated sulfonic acid polymer due to the introduction of porous substrate and lower vanadium ion permeability to decrease self-discharge were achieved than Nafion 117.

• Korea Journal of Hospital Management
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• v.12 no.4
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• pp.96-118
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• 2007

This study were tried to suggest basic materials for making education and training plan, and members of organization were researched about thinking of education and training effectiveness and perceptible level. The subjects of this study were 762 hospital employee selected from ten of university hospitals in Seoul, Incheon, and Kyung Gi which are doing an education and training, and conducted a self-completion questionnaire. As a result of study and plan for raising the effectiveness were indicated following statements. Firstly, according to the general specific, training effectiveness was appeared similar. So, it requires suitable alternatives to make educational programs. Secondly, according to analysis of education and training necessity, achieving a goal for education and training have difference. it needs to be scientific analysis about necessity of education and training. Thirdly, when contents of education and training program are satisfied to educatee and fit for them, thinking of education and training effectiveness is higher. Therefore, establishing the goal of education training is concrete, realistic, and measurable for increasing learning motivation. Next to, thinking of education and training effectiveness is higher, when education and training person in charge taught to educatee very well, and they were satisfied about teaching. Consequently, they who nourishment of education and training person in charge within company have to improve their ability. And then, when educatee fit for teaching technique and satisfied about it, thinking of education and training effectiveness is higher. So, education and training were tried to find many of technique for fitting the desire of educatee. Sixth, the more education and training environment is satisfactory, the more educatee have high thinking of education and training effectiveness. CEO in hospitals have to think about many-sided solution for employee. Seventh, the more education and training have correct achieving organizational goal, the more educatee have high thinking of education and training effectiveness. Accordingly, hospital management should make up for education and training system. Then, thinking of education and training effectiveness is higher, when education and training measure an effect, and reflect to personnel management and assessment of an employee's performance. It should be the feedback for using information which is planning education and training. In conclusion, when result of measurement of education and training reflect to make a education and training plan, thinking of education and training effectiveness is higher, and result of measurement of education and training should reflect to make a education and training plan.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.12
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• pp.549-564
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• 2017

Not only services that are provided by a single system have been various with the development of the Internet of Things and autonomous software but also new services that are not possible before are provided through collaboration between systems. The collaboration between autonomous systems is similar to the ecosystem configuration in terms of biological viewpoints. Thus, it is called the IT Ecosystem, and this concept has arisen newly in recent years. The IT Ecosystem refers to a concept that achieves a mission of each of a number of heterogeneous systems rather than a single system utilizing their own autonomy as well as achieving the objectives of the overall system simultaneously in order to meet a single common goal. In our previous study, we proposed architecture of elementary level and as well as basic several meta-models to implement the IT Ecosystem. This paper proposes comprehensive reference architecture framework to implement the IT Ecosystem by cleansing the previous study. Among them, a utility function based on cost-benefit model is proposed to solve the dynamic re-configuration problem of system components. Furthermore, a measure of using genetic algorithm is proposed as a solution to reduce the dynamic re-configuration overhead that is increased exponentially according to the expansion of the number of entities of components in the IT Ecosystem. Finally, the utilization of the proposed orchestration framework is verified quantitatively through probable case studies on IT Ecosystem for unmanned forestry management.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1775-1781
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• 2008

The effects of the type of curing agent on the swelling of the natural rubber(NR) sponge applicable to the self-sealing layer of a helicopter fuel tank were investigated. The curing systems employed were peroxide and mixed ones of sulfur and peroxide. The NR compounds were prepared in a kneader and a roll-mill. The compounds were partially cured in a press at high pressure and subsequently cured fully with expansion in another press at atmospheric pressure. The apparent density of the NR sponge was measured and the cell structure was observed with scanning electron microscopy. The swelling experiments were performed at room temperature using toluene, iso-octane, and an aircraft fuel as a solvent. More rapid volume swelling of the NR sponge cured by peroxide was achieved than cured by sulfur and peroxide with similar amount of curing agent added in rubber compounds. The apparent density and cell structure of the sponge were extremely sensitive to the amount of peroxide, which influences again the swelling behavior of the NR sponge. It is important to control properly two reactions of decomposition of foaming agent and crosslinking of NR in the mold to obtain rapid swelling of the NR sponge on contact of the fuel.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.1
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• pp.5-14
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• 2023

In this study, LiDAR-reflective black hollow-structured silica/titania(B-HST) materials are successfully synthesized by employing the NaBH₄ reduction and etching method on silica/titania core/shell(STCS) materials, which also effectively enhance near-infrared(NIR) reflectance. Moreover, core-etched supernatant solutions are collected and recycled for the synthesis of extracted silica(e-SiO₂) process, which successfully applies as filler materials for semiconductor epoxy molding compound(EMC). In detail, B-HST materials, fabricated by the sequential experimental steps of sol-gel, reduction, and sonication-mediated etching method, manifest blackness(L^*) of 13.2 similar to black paint and excellent NIR reflectance(31.1%). Consequently, B-HST materials are successfully prepared as LiDAR-reflective black materials. Additionally, core-etched supernatant solution with silanol precursors are employed for synthesis of homogeneous silica filler materials via sol-gel method. As-synthesized silica fillers are incorporated with epoxy resin and carbon black for the preparation of semiconductor EMC. Experimentally synthesized EMC exhibits comparable mechanical-chemical properties to commercial EMC. Conclusively, this study successfully proposes designing procedure and practical experimental method for simultaneously synthesizing the NIR-reflective black materials for self-driving vehicles and EMC materials for semiconductors, which are materials suitable for the industrial 4.0 era, and presented their applicability in future industries.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.1
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• pp.8-14
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• 1990

Retardation and hydrodynamic dispersion coefficient necessary for model of water and solute movement in a soil were determined for horizontal soil column with different initial soil water conditions. The soil columns were compacted with sandy loam soil. The bulk density was $1,350+50kg/m^3$, and initial water contents were 0.05, 0.08 and 0.14. Advancement of 0.05% $CaSO_4$ solution was used as the standard and advancements of 0.5% KCl, $CaCl_2$ and $KH_2PO_4$ were compared. Retardation of non-reactive $Cl^-$ was related with the initial soil water content, ${\theta}n$, as ${\theta}/({\theta}-{\theta}n)$, and anion exclusion was ignored. Retardations of active $K^+$, $Ca^{{+}{+}}$ and $H_2PO_4{^-}$ were related as 1/(R+1) $^*{\theta}/({\theta}-{\theta}n)$, in which R was retardation coefficient. Measured R was 0.64 for $K^+$, 0.80 for $Ca^{{+}{+}}$ and 2.6 for $H_2PO_4{^-}$, respectively. Calculated R using Langmuir adsorption isotherm showed fair degree of applicability. Soil water diffusivity, $D({\theta}),m^2/sec$, calculated for different initial water content showed unique function as $$log(D({\theta}))=13.448{\theta}-9.288$$ Hydrodynamic dispersion coefficient of $Cl^-$ above soil water content 0.36 was similar to soil water diffusivity and decreased to near self diffusion coefficient at soil water content near 0.2. Those of $K^+$, $Ca^{{+}{+}}$ $H_2PO_4{^-}$ at soil water content of 0.38 were $5.5{\times}10^{-6}$, $2.4{\times}10^{-6}$ and $7.1{\times}10^{-7}m^2/sec$ and decreased rapidly with decreasing soil water content lower than 0.36.