• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.1
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• pp.113-127
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• 2008

The purpose of this study was to evaluate effect of application of $ZirLiner^{(R)}$ and blasting treatments on shear bond strength of zirconia-veneered porcelain interface. 60 uncolored zirconia plates and 30 colored zirconia plates were fabricated and divided into nine groups of 10 according to blasting treatment such as as-ground, glass blasting and alumina blasting and zirliner application. Veneering porcelains were built up over the center of the treated zirconia ceramic surface using jig and fired according to the manufacturers' instructions. Each specimen was completely embedded in acrylic resin. The specimens were placed in a mounting jig and subjected to shear force by a universal testing machine. Load was applied at a crosshead speed of 0.5㎜/min until failure. Average shear strengths were analyzed with two-way analysis of variance and one-way analysis of variance and the Duncan's post-hoc test. The fracture surfaces of the failed specimens were examined by SEM. The obtained results were as follows: 1. Depending on surface treatment by blasting, the degree of roughness is revealed in the order of Glass-blasted, As-ground, and Alumnia-blasted. The roughness average of uncolored and colored zirconia ceramic were not significantly different from blasting treatments. 2. In uncolored zirconia ceramic, the shear bond strength were not significantly different from blasting treatments. However, the shear bond strength were significantly different from Zirliner application. 3. Used ZirLiner, mean shear bond strength of colored zirconia was lower than uncolored zirconia. Especially, mean shear bond strength of colored zirconia was quite low with alumina-blasting treatment. 4. SEM analysis showed that veneered porcelain failed in zirconia ceramic interface and there was no cohesive failure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4081-4086
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• 2014

Cellulose acetate butyrate (CAB) is a biodegradable resin with excellent optical properties, but it is difficult to apply film process. In this study, an attempt was made to improve the processability of CAB using polyactic acid and the mechanical properties using an impact modifier. Polylacitc acid (PLA)/Cellulose acetate butyrate (CAB) blends with an impact modifier were prepared using a twin screw extruder. The temperature range was $140^{\circ}C$ to $200^{\circ}C$, and the screw speed was fixed to 200 rpm. To evaluate the miscibility of impact modified CAB/PLA, the glass transition behavior and morphology were observed by DSC and FE-SEM. The mechanical properties were investigated by dynamic mechanical analysis (DMA) and a Universal Testing Machine (UTM). In addition, the effect of an impact modifier in the polymer matrix was determined using a notched Izod impact strength tester. Finally, the PLA/CAB/impact modifier 75/25/10 ratio was found to be a compatible system. In the 10wt.% impact modifier, the sample had a 4 times higher izod impact strength than the non-toughening composition.

• Research in Plant Disease
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• v.18 no.4
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• pp.298-303
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• 2012

Tomato yellow leaf curl virus (TYLCV), transmitted exclusively by the whitefly (Bemisia tabaci) in a circulative manner is one of the most important virus in tomato. Since the first report of TYLCV incidence in Korea in 2008, the virus has rapidly spread nationwide. TYLCV currently causes serious economic losses in tomato production in Korea. Early detection of TYLCV is one of the most important methods to allow rouging of infected tomato plants to minimize the spread of TYLCV disease. We have developed an ultra-rapid and sensitive real-time polymerase chain reaction (PCR) using a new designed real-time PCR system, GenSpectorTM TMC-1000 that is a small and portable real-time PCR machine requiring only a $5{\mu}l$ reaction volume on microchips. The new system provides ultra-high speed reaction (30 cycles in less than 15 minutes) and melting curve analysis for amplified TYLCV products. These results suggest that the short reaction time and ultra sensitivity of the GenSpector$^{TM}$-based real-time PCR technique is suitable for monitoring epidemics and pre-pandemic TYLCV disease. This is the first report for plant virus detection using an ultra-rapid real-time PCR system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.482-489
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• 2020

This study conducted a prototype development and evaluation by performing die-casting mold design, mold manufacturing, and injection condition optimization based on flow and solidification analysis to meet the needs of the coupling parts produced by die casting. Through flow analysis, the injection conditions suitable for 100% filling in the cavity were found to be a molten metal temperature of 670 ℃, injection speed of 1.164 m/s, and filling pressure of 6.324~18.77 MPa. In addition, solidification close to 100 % occurred in all four cavities when the solidification rate was 69.47 %. A defect inspection on the surface and inside the product revealed defects, such as poor molding and pores. In addition, the dimensions of the injected product were within the target tolerance and showed good results. Through the feedback of the results of flow and solidification analysis, it was possible to optimize the mold design, and the injection optimization conditions were confirmed to be a total cycle time of approximately 6.5 seconds. Good quality carrier parts with an average surface hardness of approximately 45 mm from the gate measured at 97.48(Hv) could be produced.

• Korean Journal of Agricultural Science
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• v.43 no.4
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• pp.650-655
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• 2016

Gears are components of transmission which transmit the power of an engine to a machine and offer numerous speed ratios, a compact structure, and high efficiency of power transmission. Gear train design in the automotive industry uses simulation software. However, PTO (Power Take-Off) gear design for agricultural applications uses the empirical method because of the wide range of load fluctuations in agricultural fields. The PTO is an important part of agricultural tractors which transmits the power to various tractor implements. Therefore, a simulation was essential to the optimal design of the PTO. When the PTO gear is optimally designed, there are many advantages such as low cost, reduced size, and light weight. In this study, we conducted the bending and contact safety factor simulation for the PTO gear of an agricultural tractor. The bending and contact safety factors were calculated on ISO 6336 : 2006 by decreasing the face widths of the PTO pinion and wheel gear from 18 mm at an interval of 1 mm. The safety factor of the PTO gear decreased as the face width decreased. The contact safety factors of the pinion and wheel gear were 1.45 and 1.53, respectively, when the face width was 18 mm. The simulation results showed that the face width of the PTO gear should be greater than 9 mm to maintain the bending and contact safety factors higher than 1. It would be possible to reduce the weight of the PTO gear for different uses and working conditions. This study suggests that the possibility of designing an optimal PTO gear decreases as its face width decreases.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.3
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• pp.8-14
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• 2012

Improving the speed of image processing is in great demand according to spread of high quality visual media or massive image applications such as 3D TV or movies, AR(Augmented reality). SIMD computer attached to a host computer can accelerate various image processing and massive data operations. MAMS is a multi-access memory system which is, along with multiple processing elements(PEs), adequate for establishing a high performance pipelined SIMD machine. MAMS supports simultaneous access to pq data elements within a horizontal, a vertical, or a block subarray with a constant interval in an arbitrary position in an $M{\times}N$ array of data elements, where the number of memory modules(MMs), m, is a prime number greater than pq. MAMS-PP4 is the first realization of the MAMS architecture, which consists of four PEs in a single chip and five MMs. This paper presents implementation of image processing algorithms and performance analysis for MAMS-PP16 which consists of 16 PEs with 17 MMs in an extension or the prior work, MAMS-PP4. The newly designed MAMS-PP16 has a 64 bit instruction format and application specific instruction set. The author develops a simulator of the MAMS-PP16 system, which implemented algorithms can be executed on. Performance analysis has done with this simulator executing implemented algorithms of processing images. The result of performance analysis verifies consistent response of MAMS-PP16 through the pyramid operation in image processing algorithms comparing with a Pentium-based serial processor. Executing the pyramid operation in MAMS-PP16 results in consistent response of processing time while randomly response time in a serial processor.

• The Journal of the Korea Contents Association
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• v.20 no.6
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• pp.433-438
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• 2020

The aim of this study was to investigate the mechanical properties of pit and fissure sealant containing cerium oxide nano particles(CNP). Used to mix with pit and fissure sealant (Concise^TM, USA). CNP was added into liquid (0- 4.0 wt%) of pit and fissure sealant. The specimens for the vickers hardness (VHN; 10 × 2 mm), Three-point flexure (FS; 2 × 2 × 25 mm) with flexure modulus (FM) were obtained from cements at 1, 7, and 14 days after storing in (37±1)℃ distilled water. All mechanical strength tests were conducted using machine (Instron 3344) with a cross-head speed of 1 mm/min. Data were statistically analyzed by one-way ANOVA and Duncan posthoc test(p<0.05). Mechanical properties of conventional pit and fissure sealant could be enhanced by addition of CNP. Three-point flexure and modulus of pit and fissure sealant containing CNP were showed a slightly higher value not significantly with the group(p>0.05). The vickers hardness values were increase significantly with incubation time(p<0.05). Results indicated that CNP can be used considered as potential reinforcing agent for increasing mechanical properties for conventional pit and fissure sealant. Therefore, it was suggest that the additional effects of CNP and research on a wide range of substances.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.61-67
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• 2017

Research into the selection of suitable materials and the development of fast processing methods for press die manufacturing is absolutely necessary to reduce the production time and cost. In particular, knowledge of its heat properties must be considered whendeveloping a long press die. Generally, as the main component materials of press dies, Cr, W low alloy tool steel, high carbon-high chrome steel, high speed steel, etc., are used as thetooling steel for the cold die. Machine tools and wire-cut electric discharge machining are mainly used for processing the press die parts. There are many differences in the machining time and life cycle of die parts depending on the machining process. The parts produced by milling and grinding have a high manufacturing time and cost with a long life cycle, while thosemade by milling and wire-cut discharge machining have areduced manufacturing time and cost,whereastheir die life cycle is reduced. Therefore, in this study, we will discuss amethod of improving the life cycle of the die parts by using heat treatment as a processing method that reduces the manufacturing time and cost. SEM, EDS analysis and the surface roughness analysis of the surface and center of the workpiece are used for analyzing the specimens produced by three machining methods, viz. milling - grinding, milling - wire cut discharge, and milling - wire cut discharge - heat treatment. A method of making die parts having the same life cycle as those produced by milling - grinding is developed with the milling - wire cut discharge - high temperature tempering method.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.4
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• pp.243-249
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• 2016

In this paper, we evaluate the effectiveness of mechanical horseback riding exercise training for cardiopulmonary responses in 26 healthy adults (male 14, female 12) and suggest its clinical applicability. Exercise was performed using a mechanical horseback riding machine, JOBA(R) (Panasonic Electric Works, Osaka, Japan) and riding movement speed was increased from level 2 (0.73Hz), to 4 (0.9Hz), to 6 (1.03Hz), to 8 (1.2Hz), to 9 (1.3Hz) and maintained 3minutes in each level. Heart rate, blood pressure, maximum oxygen consumption (VO2max) were measured by respiratory gas analysis system (TruOne 2400, Parvo Medics, USA) and exercise tolerance test system(Q Stress, Cardiac Science, USA). To measure exercise intensity, metabolic equivalent (MET) were measured and percent of Heart rate reserve (%HRR), percent of peak heart rate (%peak HR) and calorie consumption were calculated. The results were analysed by SPSS 18.0. We found that the exercise intensity of mechanical horseback riding exercise using JOBA(R) for 15 minutes is moderate in healthy adult who received pre-training.

• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.175-182
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• 2015

Objective : The purpose of this study was to investigate difference in fascicle behavior of the medial gastrocnemius during the locomotion with varying intensities, such as gait and one-legged and two-legged vertical jumping. Methods : Six subjects (3 males and 3 females; age: $27.2{\pm}1.6yrs.$, body mass: $62.8{\pm}9.8kg$, height: $169.6{\pm}8.5cm$) performed normal gait (G) at preferred speed and maximum vertical jumping with one (OJ) and two (TJ) legs. While subjects were performing the given tasks, the hip, knee and ankle joint motion and ground reaction force was monitored using a 8-infrared camera motion analysis system with two forceplates. Simultaneously, electromyography of the triceps surae muscles, and the fascicle length of the medial gastrocnemius were recorded using a real-time ultrasound imaging machine. Results : Comparing to gait, the kinematic and kinetic parameters of TJ and OJ were found to be significantly different. Along with those parameters, change in the medial gastrocnemius (MG) muscle-tendon complex (MTC) length ($50.57{\pm}6.20mm$ for TJ and $44.14{\pm}5.39mm$ for OJ) and changes in the fascicle length of the MG ($18.97{\pm}3.58mm$ for TJ and $20.31{\pm}4.59mm$ for OJ) were observed. Although the total excursion of the MTC and the MG fascicle length during the two types of jump were not significantly different, however the pattern of length changes were found to be different. For TJ, the fascicle length maintained isometric longer during the propulsive phase than OJ. Conclusion : One-legged and two-legged vertical jumping use different muscle-tendon interaction strategies.