• Journal of Industrial Technology
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• v.19
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• pp.67-74
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• 1999

The mechanical properties including forming limit and deep-drawability of commercially-used sheet metals were experimentally estimated in this study. Uniaxial tensile test to obtain basic mechanical properties was carried out, followed by limiting dome height (LDH) test and forming limit diagram (FLD) test to quantitatively evaluate the sheet-formability. Deep drawing and reverse drawing tests were also performed to find out the critical values of the blank holding force and the gap between the die and the blank holder which enabled the deep drawing and reverse drawing of a successful cop without any wrinkle or fracture. The thickness of the cup wall along the rolling-, transeverse- and $45^{\circ}$-directions was measured and compared with one another. And the punch force-stroke curve and the critical punch force expected from the theory coincided with the experimental result very well for mild steel while not for aluminium alloy.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.9
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• pp.157-165
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• 2002

The design of hydraulic & control system has been developed for the disc spinning machine. The hydraulic system has been designed in the overall system including the vertical & horizontal slide fur spinning works which are controlled by hydraulic servo valves in right & left side, and the clamping slide for holding & pressing blank material in center during spinning process. Based on the design concept of this hydraulic system, model test experiments for hydraulic servo control system is tested to conform confidence and applying possibility. The control system is introduced with the fuzzy-sliding mode controller for the hydraulic force control reacting force as a disturbance, because a fuzzy controller does not require an accurate mathematical model for the generation of nonlinear factors in the actual nonlinear plant with unknown disturbances and a sliding controller has the robustness & stability in mathematical control algorithm. We conform that the fuzzy-sliding mode controller has a good performance in force control for the plant with a strong disturbance. Also, we observe that a steady state error of the fuzzy-sliding mode controller can be reduced better than those of an another controllers.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.918-920
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• 2003

This paper presents the analysis of the permanent magnet overhang effect for permanent magnetic actuator. Generally, The overhang is often used to increase the force density in permanent magnet machineries. The overhang is especially profitable to reduce the volume after increasing the force density per volume when using the overhang effect of the permanent magnet. Therefore, 3D Equivalent Magnetic Circuit Network Method (3D EMCNM) has been used in this paper. According to the plunger position, flux distribution per the overhang length, and the holding force are quantitatively compared. Furthermore, an appropriate length of the overhang has been proposed. To confirm the accuracy of the analysis method, the results of 3D EMCNM and FEM(2D, 3D) are compared for the basic model.

• Food Science of Animal Resources
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• v.39 no.4
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• pp.668-676
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• 2019

This study aimed to investigate the effect of an electric field refrigeration (EFR) on the quality characteristics of pork loin including dry aging loss, pH, water holding capacity (WHC), cooking loss, color, shear force, thiobarbituric acid reactive substances (TBARS), and microbial growth during dry aging (0, 1, 2, 3, 4, 7, and 9 wk) in comparison with a commercial refrigerator (CR). Total plate counts (TPC) of the CR group approached 8.07 Log CFU/g at 2 wk of dry aging, thus indicating meat spoilage. Cooking loss, lightness, and shear force of EFR were significantly decreased (p<0.05) at subsequent aging weeks in both the EFR and CR. Aging loss, TPC, TBARS levels increased at subsequent aging weeks; however, pH values were not influenced by aging. At the same aging weeks (1 or 2 wk), the EFR group displayed significantly lower values (p<0.05) of aging loss, pH, TPC, and TBARS levels than the CR group. No significant differences in WHC, cooking loss, and shear force was observed until 2 wk of aging between the EFR and CR groups. The present results show that application of the EFR system improves the tenderness, color, and lipid oxidation stability of pork loin and extends its shelf life in comparison with a commercial refrigeration.

• Transactions of Materials Processing
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• v.24 no.1
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• pp.5-12
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• 2015

In the current study, fundamental deep drawing characteristics of Ti-6Al-4V alloy sheets were investigated to establish the effect of processing conditions on large size square deep drawn cups. To accomplish this study, FE-simulations (Abaqus) were performed to determine optimum blank size, friction coefficient, the gap between punch and die, etc. The simulated processing parameters were verified experimentally. Based on the FE-simulation results, deep drawing was performed with various blank holding loads and sample sizes. In order to improve the formability of Ti-6Al-4V sheet, various lubricant methods were evaluated. Tensile tests and thickness measurements were conducted on the formed sheets. Processing parameters including blank holding force, lubricants, and optimum blank size, were selected to achieve improved drawing quality. With the optimum processing condition, a $200mm{\times}200mm$ cup was deep drawn successfully.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.646-653
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• 2018

Marine accidents caused by dragging anchors occur constantly due to enlargement of ships' size and unusual weather conditions. Nevertheless, vessel operators rely on their experience because the calculations of actual holding power and external forces are complex and inconvenient. The purpose of this study was to propose a program for the anchor dragging risk assessment in order to provide crew and VTSO with the information to determine easily the danger of dragging and take appropriate action. The input data in this program were composed of the ship's basic particulars, anchoring condition, and external environment etc. on calculating for the wind pressure, frictional force, drift force, and holding power. Three dragging anchor accidents were applied to the program's data input at the time of the day, then the result was assessed by 'warning', which was verified with a high confidence. As a result, the risk of dragging anchors can be predicted in advance through this program. In further studies, it is necessary to simplify the input data and improve user convenience through automatic input from various equipment.

• Korean Journal of Food Science and Technology
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• v.39 no.6
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• pp.608-613
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• 2007

This study was conducted to evaluate the meat quality of pork produced by feeding fermented rice bran (FRB) (10 to 20%). In the proximate composition analysis there were no significant differences, but the FRB treated groups showed a tendency for higher moisture content and a lower fat content. There were no significant changes found in the physicochemical property analysis, except for cooking loss and water holding capacity, which are the most important factors for estimating meat quality. The cooking loss of the FRB pork was significantly lower than that of the control group (p<0.01). The water holding capacity of the 20% FRB roup was higher than that of the control group (p<0.01). The shear force value of the 20% FRB group was also higher than that of the control group, but the 10% FRB group showed no difference from the control group. The total free amino acid volume of the meat increased, depending on the volume of FRB added. The contents of glutamic acid, glycine, and alanine, which are important factors for taste and flavor, were higher in the FRB groups an the control group. In the sensory analysis, the FRB groups showed high scores for color, aroma, flavor, juiciness, taste, and overall acceptability. Taken together, adding FRB to the feed improved the quality of pork.

• Food Science of Animal Resources
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• v.36 no.1
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• pp.29-36
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• 2016

This study was performed to investigate the role of pH and temperature postmortem, and to demonstrate the importance of these factors in determining meat quality. Postmortem pH_45min (pH at 45 min postmortem or initial pH) via analysis of Pearson’s correlation showed high positive correlation with pH change pH_c24 (pH change from pH_45min to pH_24h postmortem). However, postmortem pH after 24 h (pH_24h or ultimate pH) had a high negative correlation with pH change, pH_c24, CIE L*, and protein content. Initial temperature postmortem (T_1h ) was positively associated with a change in temperature from 45 min to 24 h postmortem (T_c24) and cooking loss, but negatively correlated with water holding capacity. Temperature at 24 h postmortem (T_24h) was negatively associated with T_c24. Collectively, these results indicate that higher initial pH was associated with higher pH_c24, T_1h, and T_c24. However, higher initial pH was associated with a reduction in carcass weight, backfat thickness, CIE a* and b*, water holding capacity, collagen and fat content, drip loss, and cooking loss as well as decreased shear force. In contrast, CIE a* and b*, drip loss, cooking loss, and shear force in higher ultimate pH was showed by a similar pattern to higher initial pH, whereas pH_c24, carcass weight, backfat thickness, water holding capacity, fat content, moisture content, protein content, T_1h, T_24h, and T_c24 were exhibited by completely differential patterns (p<0.05). Therefore, we suggest that initial pH, ultimate pH, and temperatures postmortem are important factors in determining the meat quality of pork.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.2
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• pp.119-124
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• 2015

The purpose of this research is a verification of the current equation for calculating equipment number and a suggesting a method for development of a rational new equation. The equation for calculating equipment number consists of total surface area of a ship that fluid resistance act on. Equipment number determines the specification of anchoring and mooring equipment such as anchor weight, anchor chains length and diameter, the number, length and breaking load of tow lines and mooring lines. The equation for equipment number calculation is basically derived considering x, y components of a wind and current force acting on a ship. But this equation is only based on a tanker, which was main type of ships when the equation was derived. Therefore, verification of the equation is required for other types of ships, such as container carrier, LNG carrier, etc. Therefore, in this research, we find out the equation for equipment number calculation should be revised for other types of ships especially the container carrier, by comparing wind and current force acting on a ship to holding force of an anchor and anchor chains, which are selected based on the equipment number.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.2
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• pp.26-31
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• 2007

A novel scanning probe measurement system was developed to enable precise profile measurements of microaspheric surfaces. An air-bearing stylus with a microprobe was used to perform the surface profile scanning. The new system worked in a contact mode and had the capability of measuring micro-aspheric surfaces with large tilt angles and complex profiles. Due to limitations resulting from the contact mode, such as possible damage caused by the contact force and lateral resolution restrictions from the curvature of the probe tip, several system improvements were implemented. An air bearing was used to suspend the shaft of the probe to reduce the contact force, enabling fine adjustments of the contact force by changing the air pressure. The movement of the shaft was measured by a linear encoder with a scale attached to the actual shaft to avoid Abbe errors. A $50-{\mu}m-diameter$ glass sphere was bonded to the tip of the probe to improve the lateral resolution of the system. The maximum contact force of the probe was 10 mN. The shaft was capable of holding the probe continuously if the contact force was less than 40 mN, and the resolution of the probe could be as high as 10 nm, The performance of the new scanning probe measurement system was verified by experimental data.