• Proceedings of the KIEE Conference
• /
• 2003.04a
• /
• pp.289-291
• /
• 2003

This paper deals with the design of a spiral micro inductor using LTCC(Low Temperature Cofired Ceramics) technology. The inductors using the LTCC technology have some prominent properties of high integration of circuits, high confidence and low cost comparing with previously fabricated thick-film inductors. In this paper, we designed a new spiral-type micro inductor comprising a magnetic material to improve the inductance and leakage flux. we, in addition, presented the simulation results for various shapes of the magnetic material in the micro inductor, Finally application of the micro inductor to the boost DC-DC converter is investigated.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.46 no.4
• /
• pp.382-391
• /
• 2019

This study was aimed to assess the new trial for minimal cavity preparation in composite restoration combined with resin infiltration, focusing at application sequence. 32 human primary molars with early carious lesions around small cavity were selected and randomly divided into two groups, according to the sequence of cavity preparation (P), composite filling (F) and resin infiltration (I) as IPF and PFI group. Each group was assessed about amount of tooth reduction, features of resin infiltration, and marginal leakage around restoration. Amount of tooth reduction evaluated using micro-CT was decreased compared with the original lesion size in both groups. Features of resin infiltration were verified under confocal laser scanning microscopy. In both groups, infiltrant resin was found on all around the composite and maintained in spite of extent of decalcification even after artificial caries induction. Marginal micro leakage assessed with silver nitrate immersion and micro-CT was found more frequently in PFI group. The technique combining resin infiltration and composite restoration might ensure better adhesion prognosis as applied by the sequence of resin infiltration, cavity preparation, and composite filling. This new trial was thought meaningful in minimizing the cavity size and contributing to minimal invasive dentistry.

• Journal of dental hygiene science
• /
• v.11 no.4
• /
• pp.333-337
• /
• 2011

The purpose of this experiment was to examine possibility of microleakage by water, temperature change, and bite force inside the mouth during the period of using light-activated temporary filling materials. 2 kinds of light-activated temporary filling materials were used in order to measure weight and compressive strength and to evaluate microleakage between filling material and cavity wall according to frequency of thermal circulation. First, Light-activated temporary filling material was increased the weight, which was measured according to the period of using. As for the result of comparing between products, the weight of Quicks was indicated to be higher. Second, Compressive strength of Spacer had significant difference depending on period of using. However, significant difference wasn't shown in the compressive strength of Quicks. In Spacer that showed significant difference, the compressive strength increased greatly in the difference of 3 days. Third. As for micro-leakage according to frequency of thermal circulation, the microleakage was indicated to be the highest in the group that carried out 7,000 times. The group with operation of 1,000 times and the group with operation of 3,000 times were indicated the statistically lower micro-leakage than the group with operation of 7,000 times. This study brought about a rise in micro-leakage depending on the passage in the period of using. However, it is obvious fact that micro-leakage increases according to the passage of time after restoration.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.1
• /
• pp.115-121
• /
• 2005

Micromachines are extremely novel artifacts with a variety of special characteristics. Utilizing their tiny dimensions ranging roughly from 10 to $10^3$ micro-meters, the micromachines can perform tasks in a revolutionary manner that would be impossible for conventional artifacts. Micromachines are in general related to various coupled physical phenomena. They are required to be evaluated and designed considering the coupled phenomena. This paper describes finite element analysis (FEA) simulation of practical behaviors for the micro actuator. Especially, electric field modeling in micro actuators has been generally restricted to in-plane two-dimensional finite element analysis because of the complexity of the micro actuator geometry. However, in this paper, the actual three-dimensional geometry of the micro actuator is considered. The starting torque obtained from the in-plane two-dimensional analytical solutions were compared with that of the actual three-dimensional FE analysis results. The starting torque is proportional to $V^2$, and that the two-dimensional analytical solutions are larger than the three- dimensional FE ones. It is found that the evaluation of micro actuator has to be considered electrical leakage phenomenon.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.1045-1048
• /
• 2002

Micromachines are extremely novel artifacts with a variety of special characteristics. Utilizing their tiny dimensions ranging roughly from 10 to $1O^3$ micro-meters, the micromachines can perform tasks in a revolutionary manner that would be impossible for conventional artifacts. Micromachines are in general related to various coupled physical phenomena. They are required to be evaluated and designed considering the coupled phenomena. This paper describes finite element analysis (FEA) simulation of practical behaviors for the micro actuator. Especially, electric field modeling in micro actuators has been generally restricted to in-plane two-dimensional finite element analysis because of the complexity of the micro actuator geometry. However, in this thesis, the actual three-dimensional geometry of the micro actuator is considered. The starting torque obtained from the in-plane two-dimensional analytical solutions were compared with that of the actual three-dimensional FE analysis results. The starting torque is proportional to $V^2$, and that the two-dimensional analytical solutions are larger than the three-dimensional FE ones. It is found that the evaluation of micro actuator has to be considered electrical leakage phenomenon.

• Tribology and Lubricants
• /
• v.24 no.6
• /
• pp.285-290
• /
• 2008

The purpose of this paper is to present the case study of tribological failure analysis on the gear damages, oil leakage, and sealant sealing in a manual transmission of front engine and front wheel drive vehicle. The manual transmission is to change the speed range and direction of the engines depending on the driving conditions by friction driving forces with input and output gear system. The material property and surface roughness of the gears are strongly related to the gear noise and micro-vibration, oil leakage and wear, which may decrease the real contact area of the gear and the strength of the oil film thickness between the driving gear and driven one. The O-ring damage of speedometer driven gear and bad sealant sealing of oil pan may produce oil leakage through the contact surfaces, which cause the oil shortage and seizure on the sliding surfaces of the transaxle gears. In the failure case study, the proper repair working and good lubrication are very important for the long life of the transaxle without any tribological failures and oil leakage.

• Proceedings of the KIEE Conference
• /
• 1995.07b
• /
• pp.631-633
• /
• 1995

In this paper, the results of development of arrester leakage current detector using micro computer are described. This detector is based on harmonic analysis of the leakage current by FFT. For low sensitivity to disturbance, this device used optical fiber. This will be a great benefit of detecting deterioration ZnO arrester.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2019.11a
• /
• pp.241-242
• /
• 2019

This technology is a water leak repair technology using composite materials of concrete structures that block leakage of structures by injecting rapid microcement into the face of underground concrete to block water and injecting flexible glycidylacrylate. Rapid micro cement system repair materials are mixed with fine fibers to improve the flexural sensitivity of the material and to form a layer that blocks stabilized water at the back of the structure by allowing rapid and tight spatial filling during injection with high cohesion The glycidylacrylate repair material can control the expansion rate, and the external stress also has the characteristic that the form of the material is not destroyed or separated, which can also be applied to vibrating induced structures that produce repetitive fatigue loads, and has an effective durability in saline, alkali, acid (chloric acid, sulfuric acid, nitric acid).

• Journal of the Korean Society of Safety
• /
• v.26 no.4
• /
• pp.34-40
• /
• 2011

This paper is purposed to develop an leakage current detecting system(LCDS) which can prevent electrical fires on breaker capacity expansion as well as ruptures of XL(Extra long) pipelines and power failure by operation of ELB(Earth leakage breaker) at auto water machine in winter. In order to develop LCDS, this paper studied field state investigation, field state experiment, development of leakage alarm system and verification experiments. Field states investigation at livestock companies(10 companies) in cheong-won location to deduce the problems of auto water machine is analyzed. The field state experiment is conducted at B livestock company in cheong won location. The field state experiment method is measured with leakage current when ELB tripped by environment factor(fine, cloudy, and rainy day). The LCDS is developed as MCU(Micro Control Unit) part applied leakage current values at B livestock company. Verification experiments for the leakage current detecting system were conducted by two methods of current supply and field test. Results show that LCDS suggested in this paper are valuable and usable in auto water machine based on environment factor, which will prevent severe damage to human beings and properties and reduce the electrical fires in livestock.

• Journal of the Korean GEO-environmental Society
• /
• v.2 no.1
• /
• pp.67-79
• /
• 2001

The objective of this study is to determine the engineering properties of micro fine hybrid silicate grout materials that were developed recently. In this study, MSG-N type was mainly used as grout materials, and the chemical components, grain size distribution, mineral characteristics were analyzed. Moreover, the properties of active silica and ordinary portland cement acting as coagulating agent were analyzed and compared with each other. To determine the engineering properties, the bleeding test, viscosity test, coagulation test, examination with naked eye, photographing by using SEM, uniaxial compression test and in-situ application test for reclaimed ground were carried out. A series of test results showed that the strength of micro fine hybrid silicate grout materials was about twice that of ordinary sodium silicate grout materials, and alkali leakage decreased dramatically when MSG method was utilized. Especially, based on the evaluation of the application of the MSG method to field, this method would be very effective in reducing coefficient of permeability due to its excelent permeability.