• Journal of Electrochemical Science and Technology
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• v.15 no.1
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• pp.152-160
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• 2024

In this study, ZnCo₂O₄ nanoparticles were synthesized via the coprecipitation method using different annealing temperatures from 200℃ to 800℃. By varying the treatment temperature, the morphology changed from amorphous to tetragonal, and finally to polygonal particles. As temperature increased, the sizes of the nanoparticles also changed from 5 nm at 200℃ to approximately 500 nm at 800℃. The fabricated material was used to modify the working electrode of a screen-printed carbon electrode (SPE), which was subsequently used to survey the detection performance of the antibiotic, chloramphenicol (CAP). The electrochemical results revealed that the material exhibits a good response to CAP. Further, the sample that annealed at 600℃ displayed the best performance, with a linear range of 1-300 μM, and a limit of detection (LOD) of 0.15 μM. The sensor modified with ZnCo₂O₄ also exhibited the potential for utilitarian application when the recovery in a real sample was above 97%.

• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.40-41
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• 2005

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.91.1-91.1
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• 2008

• Journal of the Ergonomics Society of Korea
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• v.31 no.1
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• pp.185-189
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• 2012

Objective: The aim of this paper is to introduces Hyundai Heavy Industry's ergonomic risk assessment tool, H-OWAS, which is considering work load and frequency compared to the OWAS. Background: As prevalence of work-related musculoskeletal disorders(WMSDs) in ship building industries has been much higher than that in other industries, most of the large scaled corporations have implemented their own prevention program since legislation on the prevention of WMSDs had introduced in 2003. Method: This paper introduces WMSDs prevention program, HEMP(HHI Ergonomics Management Program) which consists of risk assessment, improvement efforts of working environments, medical treatment and training/evaluation and describes how to operate the program. We also describe application of OWAS method considering work load and frequency for risk factor analysis(H-OWAS) and shows methodology for assessing the ergonomic risk factor. And comparison of the assessment results between OWAS and H-OWAS is carried out by statistical analysis. Result: There was statistically significant difference in the assessment results between OWAS and H-OWAS, and regression shows H-OWAS explains the borg's scale of perceived exertion more clearly than OWAS. Conclusion: H-OWAS has been proved more effective tool than OWAS to evaluate ergonomic risk factor under real working condition. Application: H-OWAS can be widely applied to the many other companies when implementing the ergonomics risk assessment.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1110-1116
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• 1993

A study on optimum operation performances of power efficiency, economy and exhaust emissions for a tractor was conducted. A mathematical model of multiple degree polynomial equation was applied to established the function of solid multiple parameter curves for specific fuel consumption (ge), cabon monoxide (CO) ,hydrcarbons (HC) and cabonaceous smoke (Rb). The optimum operation theorems for economy operation indicated by ge and for exhaust emissions described by Co , HC and Rb were obtained from analytical method and performance test data. The optimum operation theorems could exhibit optimum operation working points, curves, and regions. The optimum matching relations of engine speed and transmission parameters were analyzed by using computer simulation methods in accordance with the tractor specifications , actual farm working conditions in a typical drawbar pull work such as plowing , the optimum operation objective function, the ideal transmission ratio, practical gear shif ing positions and practical travel speed of the tractor TN55 medel. The results of the anlayzes indicated clearly that the optimum power efficient operation, energy saving and pollution reducing would be realized if the tractor would be operated according to theoptimum operation methods.

• Journal of Korean Society of Forest Science
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• v.98 no.6
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• pp.690-695
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• 2009

The purpose of this research is to revealed the relationship between job satisfaction and turnover of forest workers. Data had obtained through a questionnaire, in which 155 forest workers at three national forestry cooperative federation training centers are questioned. The data had been analyzed using the factor analysis and multiple regression method. The results of the factor analysis were found 'Relation with the boss', 'Wage & safety', 'relation with co-workers', 'Job specifications', and 'Working hours'. As the result of the regression, turnover was affected by only 'Job specification', however turnover was not affected by 'Relation of the boss', 'Wage & safety', 'relation of co-workers', and 'Working hours'.

• Journal of the Korean Home Economics Association
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• v.45 no.6
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• pp.61-75
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• 2007

This paper examines the intergenerational time transfers between married women and their co-residing elderly parents, and how they affect married women's labor force participation and work hour. The sample was drawn from the "2004 Time Use Survey" conducted by Korea National Statistical Office and the Heckman's 2-step model was estimated to examine these relationships. We find that women's caregiving time for their elderly parents reduces their likelihood of participating in the labor force. On the contrary, parental time transfers for married women increases the probability of their labor force participation. We find no evidence that the actual hours of paid work is related to the time transfers between married women and their elderly parents. In other words, after married women decide to participate in the labor force, their work hours are not affected by the time spent for parents and time gained from parents to them. Parental income is positively associated with the married women's labor force participation whereas husband's income is negatively related. The married women working in service occupation and earn salaries work longer hours than those employed as laborer and wage workers. Having older parents and owning the second home reduce working hours of married women.

• Journal of Drive and Control
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• v.11 no.2
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• pp.22-29
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• 2014

This paper presents simulation-based analysis of energy flow of a wheel loader. The objective of this study is to analyze the energy flow of a wheel loader during driving and working. Because the wheel loader powertrain consists of a mechanical and hydraulic powertrain, the generated power from the engine is divided into 2 powertrains. Further, a virtual prediction of energy flow in the powertrains is a key factor in terms of optimal design. Accordingly, the simulation model that is able to predict the virtual energy flow is developed and analyzed in this study. The proposed wheel loader simulation model has been constructed in the Matlab/Simulink environment. It is expected that the developed simulation model will analyze the energy flow and efficiency in the design stage.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1874-1889
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• 2022

In this study, we evaluate the thermal-hydraulic performance and economics of Printed Circuit Heat Exchanger (PCHE) according to the channel types and associated shape variables for the design of recuperators with Sodium-cooled Fast Reactors (SFRs). To perform the evaluations with variables such as the Reynolds number, channel types, tube diameter, and shape variables, a code for the heat exchanger is developed and verified through a comparison with experimental results. Based on the code, the volume and pressure drop are calculated, and an economic assessment is conducted. The zigzag type, which has bending angle of 80° and a tube diameter of 1.9 mm, is the most economical channel type in a SFR using CO₂ as the working fluid. For a SFR using N₂, we recommend the airfoil type with vertical and horizontal numbers of 1.6 and 1.1, respectively. The airfoil type is superior when the mass flow rate is large because the operating cost changes significantly. When the mass flow rate is small, volume is a more important design parameter, therefore, the zigzag type is suitable. In addition, we conduct a sensitivity analysis based on the production cost of the PCHE to identify changes in optimal channel types.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1279-1281
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• 1998

The Co-Cr thin films are one of the most suitable candidates for perpendicular magnetic recording media. The facing targets sputtering(FTS) method has a advantage of preparing films over a wide range of working gas pressure on plasma-free substrates. In this study, we investigated the possibility of employing FTS system for depositing Co-Cr films, Co-Cr thin films were deposited with continuously sputter gas pressure ($P_{Ar}$ = 0.1 mTorr) by FTS method at temperature of $40^{\circ}C$. We find that the change of thickness and deposition rate of sputtered Co-Cr thin films affect crystal orientation and magnetic properties. Crystallographic and magnetic properties were evaluated by x-ray diffractometry(XRD) and vibrating sample magnetometer(VSM) respectively. It has been confirmed that the FTS method is very useful for preparing Co-Cr thin film recording media.