• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.12
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• pp.1004-1011
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• 2018

Recently, pyrotechnic separation nut has attracted a considerable attention because of its shock reduction effect among various pyrotechnic mechanical devices. However, its bolt loosening behavior under transverse vibration has not been studied sufficiently, since segmented nuts are utilized instead of conventional nut in pyrotechnic separation nut. With the background, bolt loosening analyses are carried out referring to Junker vibration test. The analysis procedure consists of two steps. The first step is the bolt fastening step, screwing the bolt by fastening torque. The second step is the bolt loosening step under transverse vibration. Through the procedure, bolt loosening behaviors are obtained, and the effect of clearance on loosening behavior is closely investigated for reliable design of pyrotechnic separation nut.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.9
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• pp.617-628
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• 2019

The currently considered pyrotechnic separation nut is separated through the complicated process, because it has many internal moving parts and two variable-volume chambers connected by the vent hole. Therefore, it has many design parameters. Some of these are the contact angles between internal moving parts, the masses of the internal moving parts, the inner diameter of the push rod protrusion, the initial volumes of the chambers, the mass of the explosive charge, and the diameter of the vent hole. To improve the pyrotechnic separation nut, it is necessary to understand how the behavior of the separation nut is changed according to design parameters. In this point of view, parametric studies are carried out using the previously proposed prediction model for pyrotechnic separation nut behaviors. In each case, the parameter of the interest is changed while the others are kept unchanged. From the results, it is investigated how each design parameter influences the separation behavior.

• Korean Journal of Food Science and Technology
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• v.17 no.5
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• pp.331-335
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• 1985

Series of study were conducted to develop a method for longterm storage of chest-nut with preserving it's taste and freshness. Experiments were carried out with Korean chest-nut (Castanea crenata var. Okkwang) sealed in polyethylene (P.E) film stored under the ambient and low temperature. Summarized results are as follow: After the harvest, $CO_2$ produced by chest-nut at the early storage was increased with temperature increase. Q10 mg/kg/day, the temperature index of $CO_2$production, by chest-nut ranged 2.4-2.7. It was available to store chest-nut in good condition with 8-15% total loss upto the following may at the ambient temperature sealed in 0.03 mm P.E. film, and upto the following july at the low temperature if sealed in 0.03 or 0.05 mm P.E. film. Throughout the period from one month after the innitiation upto the end of the storage, the rate of $CO_2$and $O_2$ was maintained near the optimum condition for the CA storage of chest-nut. The taste of chest-nut was improved during the storage due to increased reducing-sugar and decreased wate soluble tannin. However, the taste become bitter and unacceptable from the early stage of the storage when used the thicker P.E. film (than above mentioned) for the sealing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.35-42
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• 2019

Nut fasteners that require ultra-precise control are required in the overall manufacturing industry including electronic products that are currently developing with the automobile industry. Important performance factors when tightening nuts include loosening due to insufficient fastening force, breakage due to excessive fastening, Tightening torque and angle are required to maintain and improve the assembling quality and ensure the life of the product. Nut fasteners, which are now marketed under the name Nut Runner, require high torque and precision torque control, precision angle control, and high speed operation for increased production, and are required for sophisticated torque control dedicated to high output BLDC motors and nut fasteners. It is demanded to develop a high-precision torque control driver and a high-speed, low-speed, high-response precision speed control system, but it does not satisfy the high precision, high torque and high speed operation characteristics required by customers. Therefore, in this paper, we propose a control technique of BLDC motor variable speed control and nut runner based on vector control and torque control based on coordinate transformation of d axis and q axis that can realize low vibration and low noise even at accurate tightening torque and high speed rotation. The performance results were analyzed to confirm that the proposed control satisfies the nut runner performance. In addition, it is confirmed that the pattern is programmed by One-Stage operation clamping method and it is tightened to the target torque exactly after 10,000 [rpm] high speed operation. The problem of tightening torque detection by torque ripple is also solved by using disturbance observer Respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.461-462
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.149-150
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• 2009

• Proceedings of the Korean Society of Crop Science Conference
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• 2003.05a
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• pp.37-37
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• 2003

• Korean Journal of Food Science and Technology
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• v.35 no.3
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• pp.393-398
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• 2003

Effects of convection oven dehydration conditions on the physicochemical and sensory properties of ginkgo nut powder were examined using three types of pre-treatment on ginkgo nuts: coarse grinding of ginkgo nut (GR); coarse grinding followed by 1 min blanching (GB); 3 min blanching followed by coarse grinding (BG). Pretreated ginkgo nuts were dried in convection oven at 70 and $80^{\circ}C$ to the moisture content of approximately 5%. Rehydration rate, swelling power, solubility, lightness, and greenness of GB ginkgo nut powder dried at $70^{\circ}C$ were the most similar to those of freeze dried one. GR and GB samples dried at $70^{\circ}C$ had higher sensory values of green color and ginkgo nut flavor. Ginkgo nut powder with desirable quality attributes could be produced by drying GB in convection oven at $70^{\circ}C$ for 10 hr.

• Korean Journal of Food Science and Technology
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• v.37 no.5
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• pp.702-708
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• 2005

Cholesterol-lowering effect of pine nut on mice was investigated by examining changes in body weight, feed intake, and triglyceride, total cholesterol, high density liporotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), and very low density lipoprotein cholesterol (VLDL-C) contents in mice plasma. Changes in body weight and feed intake between pre-designed experimental animal groups fed various contents of cholesterol and pine nut and control group fed basal diet were not significantly different. Food efficiency ratio of experimental groups fed higher than 10% pine nut was significantly higher than that of control group. Apparent differences in atherogenic index representing cholesterol-lowering effect in plasma were not found among all groups fed 0-20% pine nut. Inhibition activities of water and hexane extracts of pine nut on HMG-CoA reductase and cholesterol esterase were examined in vitro. Hexane extract showed 66% inhibition effect on HMG-CoA reductase, whereas none was observed with water extract.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.140-146
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• 2000

The physicochemical properties, such as retrogradation, fat acidity and viscosity, on the pine nut's gruel at various contents of pine nut (0, 1, 3 and 5%) during storage at 4, 25 and $40^{\circ}C$ were investigated. The degree of retrogradation was increased rapidly at the initial storage stage. The lowest value (about 10%) of the degree of retrogradation was observed in the gruel sample containing 3% of pine nut. Also, the rate constant of retrogradation was showed the lowest value (0.0422) in the gruel containing 3% of pine nut regardless of storage temperatures. The fat acidity was showed the lower value than 30 mg KOH in all samples. The viscosity increasing velocity(RVU/min) between holding strength and final viscosity was decreased as the pine nut's content was increased. However, it was not affected by the storage temperatures.