• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.1
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• pp.13-19
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• 2017

The use of ultrasonic surgery units and scalers are steadily increasing in the field of dentistry. Such units and scalers should be evaluated before they are commercialized because the mechanical performance and stability of equipment is crucial for patients. Hence, we created a hand-piece moving system that can test bone cutting and teeth scaling. The purpose of this study was to evaluate the teeth scaling performance of ultrasonic scaler unit. Additionally, we measured the temperature distribution and noise during the test. through an experimental test, we found that a high output of an Ultrasonic NX device can cause serious damage to the teeth surface, and it was not within range in heat generation distribution and noise test.

• Journal of Biosystems Engineering
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• v.31 no.2 s.115
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• pp.121-127
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• 2006

An Altari radish pre-processing system, which feasible to process automatically such operations as leaf and root tail cutting and root peeling, for kimchi production was accomplished based on the foregone serial studies. In this study, the performances of the developed prototype machine, considered as a commercializing level, were analyzed and evaluated. The prototype machine attached Tiny PLC automatic control system was performed the sequent function as the rate of successful peeling was more than 98% for the Altari radish less than 70 mm diameter of a radish. The operating efficiency of this was 9 see/each, 128 kg/h, and it means as much as $5{\sim}6$ times that of a woman labor's. The sanitation and taste of the mechanized-processed Altari radish kimchi was almost same as that of the handmade. And they were suitable for manufactory of kimchi as the both short term ripening and storing kimchi. Developed machinery with one peeling device and two peeling devices that compared with hand processing, it was analyzed that the break-even yearly working days were 28 days and 19 days, and the break-even yearly processing amount were 28,700 kg, 32,400 kg, respectively.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1998.04b
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• pp.6-6
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• 1998

In 1957, the first magnetic disk drive compatible with a movable head was introduced as an external file memory device for computer system. Since then, magnetic disks have been improved by increasing the recording density, which has brought about the development of a high performance thin film magnetic head. The thin film magnetic head has a magnetic circuit on a ceramic substrate using IC technology. The physical property of the substrate material is very important because it influences the tribology of head/disk interface and also manufacturing process of the head. $Al_{2}O_{3}$-TiC ceramics, so called ALTIC, is known to be one of the best substrate materials which satisfies this property requirement. Even though the head is not in direct contact with the disk, frequent instantaneous contacts are unavoidable due to its high rotating speed and the close gap between them. This may cause damage in the magnetic recording media and, thus, it is very important that the magnetic head has a good wear resistance. $Al_{2}O_{3}$-TiC ceramics has an excellent tribological property in head/disk interface. Manufacturing process of thin film head is similar to that of IC, which requires extremely smooth and flat surface of the substrate. The substrate must be readily sliced into the heads without chipping. $Al_{2}O_{3}$-TiC ceramics has excellent machineability and mechanical properties. $Al_{2}O_{3}$-TiC ceramics was first developed at Nippon Tungsten Co. as cutting tool materials in 1968, which was further developed to be used as the substrate materials for thin film head in collaboration with Sumitomo Special Metals Co., Ltd. in 1981. Today, we supply more than 60% of the substrates for thin film head market in the world. In this paper, we would like to present the sintering process of $Al_{2}O_{3}$-TiC ceramics and its property in detail.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.2
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• pp.364-370
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• 2002

A banknote counter is a machine that automates counting the money in some agencies to treat much banknotes as well as general banking agencies. The banknote counter materialized in this paper is the machine that adds the function of banknote sorting, detecting plural banknote and detecting counterfeit banknote to an existing banknote counter. The technique of sensor signal processing are used for banknote sorting. The technique of sensor application and data processing are used for detecting counterfeit banknote. The technique of precision equipment design and microprocessor application are used for high speed count. Software improved in debugging and difficulties to link with additional hardware. It was materialized through effective control algorithm and real-time signal processing with C-language on the basis of RTOS(real-time operating system) Photodiode, its applications and a magnetic resistance sensor are used as a sensor device with regard to hardware cost -cutting and process velocity. PCF80C552-24 of Philips using Intel I8051 core is used as a control microprocessor. As the results so far achieved, counterfeit banknotes made by the use of a color duplicator and a color Printer, are distinguished from real banknotes through mixing an optical with a magnetic sensor. and, in case that there are some different banknotes while counting, it is prevented for them to be counted without discriminating from the same kind of banknotes in addition to the fu notion of banknote sorting.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.7
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• pp.1026-1033
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• 2009

Fine ceramics have high strength, excellent wear resistance, chemical stability and high strength at high temperature and are receiving attention in various fields such as construction, engineering, aerospace and marine science. Finish machining process is required to obtain precise ceramics components because sintering process necessary for obtaining high strength and high quality ceramics reduces the dimensions of components and precision of shape. But high strength and brittleness of ceramics materials cause difficulty in processing. So a process for obtaining wanted dimensions is studying using high temperature which makes ceramics softened and thermal affected recently. Laser beam is a very useful optical device for these kinds of processes. Laser process such as laser cutting, laser machining, laser heat treatment and laser-assisted machining(LAM) is researching to manufacture practical ceramics components using intense laser source which can cause local softening and damage of workpiece. In this paper, microstructural and mechanical properties of silicon nitride heated are studied as a basic study for researching of ceramics process by laser beam. The surface variation of HIP and SSN-silicon nitride was analyzed with SEM and EDS. A processing at $1,300^{\circ}C$ or above causes N element to combine into $N_2$ gas and the gas busts from surface. These phenomena make bloat, craters and heat defects on the surface of silicon nitride. Also, oxygen content is largely increased to oxidize the surface and it causes changing of phases and reducing of hardness of surface.

• Journal of Advanced Navigation Technology
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• v.21 no.5
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• pp.466-471
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• 2017

SOTM is a device for the satellite communication on the move. Many studies are conducted on microstrip, waveguide and array antenna for the low profile of the SOTM's antenna. But those antennas have a problem that is difficult to adjust the polarization, and for that reason we have studied the parabolic antenna structure. The general form of parabolic reflector structure is circular, but we used cut-off shape reflector by cutting the upper and lower reflector for low profile antenna. Accordingly, this results in the decrease of reflector area which causes reduced gain and G/T ratio. In order to solve this problem, we have transformed and designed the sub reflector for improving the efficiency and gain of the cut- off shape parabolic antenna.

• Restorative Dentistry and Endodontics
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• v.14 no.1
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• pp.179-188
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• 1989

The purpose of this study was to measure Micro vicker's hardness of 4 kinds of anterior Composite resins (Pyrofil light bond anterior, Lite-fil anterior, Photo clear fil anterior, Silux) and 6 kinds of posterior Composite resin (Pyrofil light bond posterior. Lite-fil posterior, Photo clear fil posterior, Occlusin posterior, Palfique light posterior, P-30, posterior) according to deference of depth and distance of light tip from surface of composite resin. Each composite resin was filled into Teflon tube of 5mm in diameter and 5mm in depth, celluloid matrix was covered and the light in accordance with each composite resin was irradiated in distance of zero millimeter and 1 cm from light tip to surface of composite resin for 30 seconds. Specimens were sectioned longitudinally with cutting device. Microvicker's hardness measurements ware made at the depth of surface, 1mm, 2mm, 3mm, 4mm and 5mm from the surface to deep portion. Vicker's hardness numbers were taken on each depth under 200gm load for 30 seconds with MVK-E. The following results were: 1. The highest hardness value was measured at 1 mm depth. Then the deeper the depth, the lesser the hardness was observed. 2. The hardness value of anterior composite resins is lower than one of posterior composite resins. 3. Hardness number of composite resin irradiated in distance of zero millimeter from surface of composite resin was higher than one of 1 cm from surface of composite resin. 4. The pattern of hardness change at varying depth was similar to all the experimental material with no relation to distance of light from specimen.

• Journal of Mechanical Science and Technology
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• v.19 no.5
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• pp.1158-1168
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• 2005

A shunt from the left ventricle to the left anterior descending artery is being developed for coronary artery occlusive disease, in which the shunt or conduit connects the the left ventricle (LV) with the diseased artery directly at a point distal to the obstruction. To aid in assessing and optimizing its benefit, a computational model of the cardiovascular system was developed and used to explore various design conditions. Computational fluid dynamic analysis for the shunt hemodynamics was also done using a commercial finite element package. Simulation results indicate that in complete left anterior descending artery (LAD) occlusion, flow can be returned to approximately 65% of normal, if the conduit resistance is equal for forward and reverse flow. The net coronary flow can increase to 80% when the backflow resistance is infinite. The increases in flow rate produced by asymmetric flow resistance are enhanced considerably for a partial LAD obstruction, since the primary effect of resistance asymmetry is to prevent leakage back into the ventricle during diastole. Increased arterial compliance has little effect on net flow with a symmetric shunt, but considerably augments it when the resistance is asymmetric. The computational results suggest that an LV-LAD conduit will be beneficial when the resistance due to artery stenosis exceeds 27 PRU, if the resistance is symmetric. Fluid dynamic simulations for the shunt flow show that a recirculating region generated near the junction of the coronary artery with the bypass shunt. The secondary flow is induced at the cutting plane perpendicular to the axis direction and it is in the attenuated of coronary artery.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.8
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• pp.590-596
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• 2016

Biopsy is a typical needle type intervention procedure performed under radiographic image equipment such as computed tomography (CT) and cone-beam CT. This minimal invasive procedure is a simple and effective way for identifying cancerous condition of a suspicious tissue but radiation exposure for the patients and interventional radiologists is a critical problem. In order to overcome such trouble and improve accuracy in targeting of the needle, there have been various attempts using robot technology. Those devices and systems, however, are not for full procedure automation in biopsy without consideration for tissue sampling task. A robotic end-effector of a master-slave tele-operated needle type intervention robot system has been proposed to perform entire biopsy procedure by the authors. However, motorized sampling adopted in the device has different cutting speed from that of biopsy guns used in the conventional way. This paper presents the design of a novel robotic mechanism and protocol for the automation of biopsy procedure using spring-triggered biopsy gun mechanism. An experimental prototype has been successfully fabricated and shown its feasibility of the automated biopsy sequence.

• Journal of Technologic Dentistry
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• v.38 no.4
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• pp.255-262
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• 2016

Purpose: This study examined the effect of wettability of gypsum materials and rubber impression material on the marginal fitness of zirconia copings. Methods: Three commercially available gypsum materials(Fugirock EP, Snow Rock, Tuff Rock) and three zirconia blocks(iJAM Emerald, LUXEN Smile block, ICE Zirkon transluzent) were studied. The zirconia copings were fabricated by using dental CAD/CAM system. Contact angles on the impression materials were measured with contact angle measuring device. Silicone replica method was used to measure the marginal fitness and cutting was performed on the bucco-lingual and mesio-distal sides. It were observed with a stereomicroscope at °ø40 magnification. The data were statistically analyzed with One-way ANOVA. Results: Mean values of contact angles were $58.3{\pm}0.7^{\circ}$ for Tuff Rock, $77.5{\pm}0.5^{\circ}$ for Fugirock EP and $87.8{\pm}0.5^{\circ}$ for Snow Rock and the difference between them was statistically significant(p<0.05). The smallest values of marginal fitness for the JF groups were $30.7{\pm}3.0{\mu}m$ for bucco-lingual direction, $29.3{\pm}3.0{\mu}m$ for mesio-distal direction. One-way ANOVA showed statistically significant difference between groups for marginal fitness(p<0.05). Conclusion: Tuff rock gypsum material had superior wettability to others. The mean marginal fitness of the Tuff rock gypsum material group were significantly better than other groups. Thus they can be also expected to show clinically satisfactory marginal fitness.