• Journal of Power System Engineering
• /
• v.21 no.3
• /
• pp.37-44
• /
• 2017

In this study, failure analysis of the angular pin for molding machines to aluminum component molding was carried out. SM45C steel was used for the angular pin, it was surface hardened by the induction surface hardening heat treatment. The cross section of damaged angular pin was observed, and micro Vickers hardness value from the fractured part was measured. Brittle fracture was occurred from the fracture surface of angular pin, therefore, impact toughness value was evaluated by V-notch Charpy impact test. It was confirmed that the impact absorption energy was high when was tempered at a high temperature for a long time, and the toughness was slightly increased. Also, 2-parameter Weibull statistical analysis was investigated in order to evaluate the reliability of the measured micro Vickers hardness values and absorbed energy. The micro Vickers hardness and absorbed energy well followed a two-parameter Weibull probability distribution, respectively. The reverse design against angular pin was proposed as possible by using test results.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.11
• /
• pp.1840-1848
• /
• 2003

This paper presents the structural analysis and optimum design of a vertical micro-gyroscope with decoupled 2 degrees of freedom (DOF), driven by electrostatic force. Simplified beam models were presented to derive the structural stiffness of the driving spring of the U shape and the sensing spring of I shape. A finite element analysis (FEA) was performed to validate each derivation. A total mass and a polar mass moment of inertia were also obtained and used in calculating the resonance frequency at each mode of the 2 DOF. The resonance frequencies of the total system were calculated using the proposed models and it has been found that they were in excellent agreement with those of the FEA. Finally, the developed analysis program was then linked to an optimum design module, and an optimum design of the micro-gyroscope was successfully performed.

• Journal of Power System Engineering
• /
• v.20 no.5
• /
• pp.5-13
• /
• 2016

This study is on wear damage of the material for a molding machine that be used at finally cutting of metal beam made in roll forming process of vehicle bump beam process line. SKD11 steel was used with the material for cutting mold jig. In the cutting mold jig, Ti diffusion heat treatment after vacuum heat treatment was carried out for upgrade of surface hardness and anti-wear. Also, the heat treatments by various methods were performed to compare the wear damage degree against above the existing heat treatment. Wear loss and friction coefficient were obtained from wear test. And, micro Vickers hardness values were compared with damaged parts or not of cutting mold jig. Micro Vickers hardness value appeared higher at the undamaged part by Ti diffusion heat treatment. The micro Vickers hardness well followed a two-parameter Weibull probability distribution.

• Advances in concrete construction
• /
• v.10 no.3
• /
• pp.257-269
• /
• 2020

The aim of this study is to investigate the flexural performance of hybrid fiber reinforced self-compacting concrete (HFRSCC) having different ratio of micro and macro steel fiber. A total of five mixtures are prepared. In all mixtures, the sum of the steel fiber content is 1% and also water/binder ratio is kept constant. The amount of high range water reducer admixture (HRWRA) is arranged to satisfy the workability criteria of self-compacting concrete. Four-point bending test is carried out to analyze the flexural performance of the mixtures at 28 and 56 curing days. From the obtained load-deflection curves, the load carrying capacity, deflection and toughness values are investigated according to ASTM C1609, ASTM C1018 and JSCE standards. The mixtures containing higher ratio of macro steel fiber exhibit numerous micro-cracks and, thus, deflection-hardening response is observed. The mixture containing 1% micro steel fiber shows worst performance in the view of all flexural parameters. An improvement is observed in the aspect of toughness and load carrying capacity as the macro steel fiber content increases. The test results based on the standards are also compared taking account of abovementioned standards.

• The Journal of Asian Finance, Economics and Business
• /
• v.9 no.9
• /
• pp.205-216
• /
• 2022

This study investigates the effect of serv-qual and reputation on customer loyalty through the trust of deposit customers in Micro Finance Institutions. The population was deposit customers at BMT distributed into 5 provinces of the Special Region of Yogyakarta, and a survey was conducted from January 2021 to February 2022. The probability random sampling technique was used to select the final sample, and a total of 221 responses were collected using a questionnaire. Technical data analysis was done using the Structural Equation Modeling (SEM), supported by AMOS 22.0 program. The results showed that serv-qual and reputation have a positive and significant impact on the trust and loyalty of deposit customers at BMT. Customers positively and significantly impact the relationship between serv-qual and reputation on customer loyalty. The biggest contribution to loyalty was generated by the variable customer trust (0.399), followed by service quality (0.359) and reputation (0.166). Micro Finance Institution needs to improve the management of deposit customers by improving serv-qual, reputation, and customer trust and conduct comparative research between conventional financial institutions and other informal financial service institutions.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.6 no.4
• /
• pp.325-330
• /
• 2005

A lever type CO micro gas sensor was fabricated by MEMS technology. In order to heat up the gas sensing material, $SnO_2$, to a target temperature, a micro heater was built on the gas sensor. The heater and electrodes were hanged on the air as a bridge type to minimize the heat loss to the silicon base. The sensing material laid on the heater and electrodes and did not contact with the silicons base. The temperature distribution of micro gas sensor was analyzed by a CFD program, FLUENT. The results showed that the temperature of silicon wafer base was almost similar to that of the room temperature, which indicates that the heat generated at the micro heater heated up effectively the sensing material. The required electric current of micro heater to heat up the sensing material to the target temperature could be predicted.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.834-836
• /
• 2008

We demonstrated micro-scale conducting polymer patterning based on a selective surface treatment. A substrate with a patterned photoresist was immersed into OTS (Octadecyltrichlosilnae) solution. The protected substrate areas were hydrophilic after removing the PR resist, where a conducting polymer solution was coated selectively by spin-coating method.

• Fire Science and Engineering
• /
• v.31 no.2
• /
• pp.113-118
• /
• 2017

The purpose of this study was to compare the ventilatory volume and airway pressure using Oxylator EM-100, MicroVenT CSI-3000, OXY-LIFE II. The data were obtained from February 13 in 2017 andanalyzed using the SPSS WIN 18.0 program. The results of theventilatory volume showed the Oxylator EM-100 551.44 ml (${\pm}18.70$), MicroVenT CSI-3000 527.26 ml (${\pm}17.98$), and OXY-LIFE II 369.46 ml (${\pm}12.30$). The airway pressure showed the Oxylator EM-100 $11.89cmH_2O$ (${\pm}.41$), MicroVenT CSI-3000 $11.66cmH_2O$ (${\pm}.34$), and OXY-LIFE II $8.02cmH_2O$ (${\pm}.25$). This study will provide the basic data for an appropriate ventilation method by an oxygen supply device including Oxylator EM-100, MicroVenT CSI-3000, and OXY-LIFE II.

• Food Science of Animal Resources
• /
• v.35 no.4
• /
• pp.459-465
• /
• 2015

Bovine milk provides essential nutrients, including immunologically important molecules, as the primary source of nutrition to newborns. Recent studies showed that RNAs from bovine milk contain immune-related microRNAs (miRNA) that regulate various immune systems. To evaluate the biological and immunological activity of miRNAs from milk products, isolation methods need to be established. Six methods for extracting total RNAs from bovine colostrums were adopted to evaluate the isolating efficiency and expression of miRNAs. Total RNA from milk was presented in formulation of small RNAs, rather than ribosomal RNAs. Column-combined phenol isolating methods showed high recovery of total RNAs, especially the commercial columns for biofluid samples, which demonstrated outstanding efficiency for recovering miRNAs. We also evaluated the quantity of five immune-related miRNAs (miR-93, miR-106a, miR-155, miR-181a, miR-451) in milk processed by temperature treatments including low temperature for long time (LTLT, 63℃ for 30 min)-, high temperature for short time (HTST, 75℃ for 15 s)-, and ultra heat treatment (UHT, 120-130℃ for 0.5-4 s). All targeted miRNAs had significantly reduced levels in processed milks compared to colostrum and raw mature milk. Interestingly, the amount of immune-related miRNAs from HTST milk was more resistant than those of LTLT and UHT milks. Our present study examined defined methods of RNA isolation and quantification of immune-specific miRNAs from small volumes of milk for use in further analysis.

• Journal of Sensor Science and Technology
• /
• v.6 no.3
• /
• pp.228-236
• /
• 1997

Radioactive materials need to control, measure and protect precisely the overflow because they are dangerous. In this paper, GM-counter type radiation detector system, that can precisely measure the quantity of radioactivity using improved counting program is designed and program that can store and transfer the counted data is studied. The manufactured system, counting system of GM-counter type radiation detector, and counter program can be utilized to measure them at various methods in an atomic power plant and research centers.