• Journal of Power System Engineering
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• v.22 no.6
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• pp.58-66
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• 2018

The use of external gear pumps is an effective way to achieve adequate performance at low cost when composing hydraulic systems. The biggest drawback, on the other hand, is the accompanying noise. Gears of continuous contact shape are actively used for the pump recently. The continuous contact shape must be the helical type due to the nature of the gear pump that is driven only by the drive gear. In this paper the theoretical shape of continuous contact gear is analyzed using simple rack shape of straight lines and two circular arcs. Using such geometry, the theoretical equation will be developed by envelope curves according to the conjugate gear shape rules. After checking the validity of the theory by the shape of gear rules, the grinding shape was also developed. The 3D shapes using equation can be also drawn. It was also shown that contact ratio and radius of curvature are easily developed by the theoretical equations.

• Transactions of Materials Processing
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• v.28 no.5
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• pp.239-246
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• 2019

Various surface texturing techniques have been studied because of the effective applicability of micro or nano scale surface patterns. Particularly, the most promising types of patterns include the hierarchical patterns, which consists of micro/nano structures. Different processes such as MEMS, laser machining, micro cutting and micro grinding have been applied in the production of hierarchical patterns on various material surfaces. This study demonstrates the process of hot imprinting to induce the hierarchical patterns on the Al alloy surfaces. Wire electrical discharge machining (WEDM) process was used to imprint molds with micro scale sinusoidal pattern. In addition, the sinusoidal pattern with rough surface morphology was obtained as a result of the discharge craters. Consequently, the hierarchical patterns consisting of the sinusoidal pattern and the discharge craters were prepared on the imprinting mold surface. Hot imprinting process for the Al plates was conducted on the prepared mold, and the replication performance was analyzed. As a result, it was confirmed that the hierarchical patterns of the mold were effectively duplicated on the surface of Al plate.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.1
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• pp.147-154
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• 2020

The exterior finishing of reinforced concrete buildings is one of the important factors to prevent durability and prevent natural environment or disaster such as temperature, snow, wind, rain from the outside as well as external design of buildings. Finishing methods can be divided into wet and dry methods. The wet method using paint is relatively easy to construct, but it requires repair and reinforcement every 1 to 5 years and requires a lot of LCC for maintenance. Finishing method using panel has good durability, but it is difficult to install and expensive. Therefore, in this paper, we evaluate the bond strength for the application of the metal spray method in order to overcome the problems of existing methods. Experimental results show that the sandblast + surface roughness agent(S-R(Y)) has a roughness of 41.16 ㎛ and the bond strength is about 3.19 MPa, which is the highest bond strength. In addition, the grinding + surface roughness agent(G-R(Y)) application showed roughness of about 36.59 ㎛ and secured the bond strength performance of 2.94 MPa.

• Journal of Practical Agriculture & Fisheries Research
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• v.3 no.1
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• pp.102-115
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• 2001

Through out the last few decades, processing methods for ingredients of feed grains, such as grinding, flaking, extrusion, soaking, cracking etc., have been adopted in order to improve the nutrient digestibility in ruminants. Among feed grains, processing methods for whole corns have been the most frequently studied since corns are utilized as the thumb ingredients in formulating feeds. In these days, flaking of whole corns is the most incessantly used in formulation feeds, resulting in enhancing the performance of ruminants. Recently formulating non-forage feed for beef cattle, especially Holsteins, without processing whole corns is carrying out through various feed companies with expectations of whole corns acting like forages. However, it can not be ruled out that whole corns might possibly result in decreasing the productivity due to the depression of nutrient utilizations. Therefore, one must reevaluate the non-forage feeds as well as makes an effort to develop the rational and effective methodology in processing whole corns with the consideration of rumen eco-system.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.1
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• pp.123-128
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• 1994

A high speed spindle system for machine tools can be used to reduce the machining time, to improve the machining accuracy, to perform the machining of light metals and hard materials, and to unite the cutting and grinding processes. In this study, a high speed spindle system is developed by applying the oil-air lubrication method, angular contact ball bearings, injection nozzles with dual orifices, cooling jacket and so on. And an air cooling experiment for evaluating the performance of the spindle system is carried out. Especially, in ofder to establish the air cooling conditions related to the development of a high speed spindle system, the effects of cooling air pressure, oil supply rate, air supply rate and rotational spindle speed are studied and discussed on the bearing temperature rise and frictional torque. Also the effects of cooling air pressure, rotational spindle speed and spindle system structure is investigated on the bearing temperature distribution. The experiment on the test model reveals the usefulness of the air cooling method.

• Design & Manufacturing
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• v.18 no.2
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• pp.9-16
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• 2024

Recently, there has been extensive research conducted on the miniaturization of semiconductors and the improvement of their integration to achieve high-quality and high-performance electronic devices. To integrate and miniaturize multiple semiconductors, thin and precise wafers are essential. The backgrinding process, which involves high-precision processing, is necessary to achieve this. The backgrinding system is used to grind and polish the back side of the wafer to reduce its thickness to ㎛ units. This enables the high integration and miniaturization of semiconductors and a flattening process to allow for detailed circuit design, ultimately leading to the production of IC chips. As the backgrinding system performs precision processing at the ㎛ unit, it is crucial to determine the stability of the equipment's rigidity. Additionally, the flatness and surface roughness of the processed wafer must be checked to confirm the processability of the backgrinding system. IIn this paper, the goal is to verify the processability of the back grinding system by analyzing the natural frequency and resonance frequency of the equipment through computer simulation and measuring and analyzing the flatness and surface roughness of wafers processed with backgrinding system. It was confirmed whether processing damage occurred due to vibration during the backgrinding process.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.10
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• pp.1405-1409
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• 2017

Objective: This experiment was to determine proper physical traits in the diet for goats by investigating the effects of physically effective neutral detergent fiber (peNDF) content on dry matter intake (DMI), digestibility, and chewing activity in black goats fed with total mixed ration (TMR). Methods: Six growing wethers of Korean native black goats (Capra hircus coreanae) aged 8 months and weighing between 26.9 kg and 27.1 kg ($27.03{\pm}5.05kg$) were used in this experiment. Three diets of varying peNDF content were obtained by original TMR (T1), 12,000 rpm grinding (T2), and 15,500 rpm grinding (T3) of the same TMR diet. The $peNDF_{1.18}$ content of the experimental diets was 23.85%, 21.71%, and 16.22% for T1, T2, and T3, respectively. Results: Average daily gain (ADG) was higher in T2 group compared to those of the control and T3 groups, but ADG and DMI were not affected by the dietary particle size and peNDF content. Also, there was no difference between apparent nutrient digestibility of dry matter, crude fiber, ether extract, neutral detergent fiber, and acid detergent fiber. Although there was no significant difference, rumination and total chewing time were associated with decreased peNDF content. Conclusion: The feeding of peNDF-based TMR showed no impact on apparent nutrient digestibility and nitrogen balance. Further studies are required with a wider range of dietary peNDF level and particle size to better identify the effect of dietary peNDF and particle size on chewing activity and performance in goats.

• Korean Journal of Construction Engineering and Management
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• v.7 no.6
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• pp.79-89
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• 2006

Current removing process is labor intensive and time consuming, employing a conventional grinding type manual machine. From a social and economic point of views, these kinds of manual tasks bring about social inconvenience and economic loss including traffic jam and high labor costs. The objective of the study was to develop and evaluate a road stripe removal equipment using water jet technology. The following shows the results. First, It was analyzed that the obtainable productivity from the equipment developed in the study is 280% compared to the current equipment. In this study, it was also calculated the Benefit/Cost Ratio and the result showed that the ratio is 3.28, so it is expected that the equipment can produce great benefits for the relevant companies. Second, an analysis was also conducted on the traffic congestion cost, and the equipment could save about \2,550 million per day compared to the conventional equipment. Therefore, it is analyzed that the economic viability of the equipment is sufficient.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.6
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• pp.737-745
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• 2008

Recent developments of process and measurement technology bring much interest to the online monitoring of process operations such as milling, grinding, broaching, etc. The objective of online monitoring systems is to detect process changes as early as possible. This is helpful in protecting facilities against unexpected failures and then preventing unnecessary loss. This paper investigates, when the process monitoring data are obtained as a profile, the monitoring performances of a statistical $T^2$-statistic and a feedforward neural network by using a wavelet transform. Numerical experiments using cutting force data presented by Axinte show that the proposed wavelet based $T^2$-test has an acceptable power in detecting profile changes. However, its operating characteristic is very sensitive to autocorrelation. On the contrary, compared with $T^2$-test, the neural network has more stable performance in the presence of autocorrelation. This indicates that an adaptive feature to analyze noises should be incorporated into the wavelet based $T^2$-test.

• Tribology and Lubricants
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• v.39 no.1
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• pp.28-34
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• 2023

Because of their cleanliness, low friction, and high stiffness, aerostatic bearings are used in numerous applications. Aerostic bearings that use porous materials as means of flow restriction have higher stiffness than other types of bearings and have been successfully applied as guide bearings, which have high motion accuracy requirements. However, the performances of porous bearings exhibit strong nonlinearity and can vary considerably depending on design parameters. Therefore, accurate prediction of the performance characteristics of porous bearings is necessary or their successful application. This study presents a porous bearing design and performance analysis for a spindle used in wafer polishing. The Reynolds and Darcy flow equations are solved to calculate the pressures in the lubrication film and porous busing, respectively. To verify the validity of the proposed analytical model, the calculated pressure distribution in the designed bearing is compared with that derived from previous research. Additional parametric studies are performed to determine the optimal design parameters. Analytical results show that optimal design parameters that obtain the maximum stiffness can be derived. In addition, the results show that cross-coupled stiffness increases with rotating speed. Thus, issues related to stability should be investigated at the design stage.