• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1276-1277
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• 2006

The ever increasing requirements on today's compacts with regard to their geometry and precision call for flexible high-precision and most capable production systems. DORST Technologies has coped with these requirements by developing the new HP series for pressing forces between 1600 kN and 16000 kN and the new HS series for pressing forces between 150 kN and 1200 kN. These fully hydraulic presses featuring upper ram, lower ram, core rod, filler, up to 4 lower tool levels and up to 4 upper tool levels with closed-loop controlled movements. Thanks to latest servo technology and an electronic bus system it is possible to have all movements closed-loop controlled in the desired relation to each other. Thus, today's hydraulic presses provide high stroke rates, low energy consumption and a user-friendly interface. The input of data is carried out via clearly arranged screen masks on a touch-screen. The innovative DORST $IPG^{(R)}$ (Intelligent Program Generator) has been designed to support the set-up staff in preparing and optimizing the toolprogram. The combination of the machine type with the hydraulic unit determines the productivity in consideration of the specific application and the part to be pressed. Thanks to the closed-loop control circuits, DORST hydraulic automatic presses of the latest generation ensure unmatched precision and repeatability - and consequently process reliability - often without necessitating subsequent machining steps.

• Korean Journal of Food Science and Technology
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• v.28 no.4
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• pp.638-643
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• 1996

The efficiency of dewatering of soybean milk residue was improved by hydraulic pressing after pH adjustment to 4.5 with organic acids such as acetic and lactic acids. Water content of raw soybean milk residue was reduced from 80% to 72% by pressing after pH adjustment, while only to 78% by the conventional hydraulic press. The water content of the residue after pH adjustment was further reduced to 63% by hydraulic pressing with ohmic heating. The pH adjustment facilitated separation of cake from the filter cloth and reduced the solid content of the expressed liquid from 10 to 3%.

• 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.

• Transactions of Materials Processing
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• v.16 no.2 s.92
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• pp.132-137
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• 2007

A double roll rotary forming equipment is presented in this paper. The equipment is developed for joining the socket with the ball of a concave piston assembly with its geometrical tolerance requirements satisfied. The equipment is composed of a lathe, a double roll system and a roll pressing unit driven by the hydraulic system. The workpiece rotates by spindle chuck of the lathe while the double roll system approaches perpendicularly to the central line of the workpiece. The equipment is successfully applied to precision joining of the ball and the socket fur the concave piston assembly of a high pressure hydraulic pump.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.3
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• pp.166-174
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• 2000

Anchovy, EngrauEis japonica scoop nets are used in the coastal of Southern and Cheju of Korea. Especially in the Cheju, the fishing gear of scoop nets consists of upper boom, lower boom, pressing stick and bag net. They are operated by fishing boats of 6 to 10 ton class and 8 persons on board. The booms are controlled by side drum, and the net and pressing stick are hauled by only human power in operating. Therefore this fishery needs to large labor and heavy human power and has much risk. Three kinds of hydraulic winding device which controls two booms was designed and manufactured to reduce heavy labor force of scoop nets, and trial in the sea was carried out to test their performances using the commercial fishing boats of 6 ton class. The proper capacity of hydraulic pump and motor were determined by model test of boom 1/5 scale. The results obtained are as follows, 1. Tension of boom which is being drawn was the strongest and 187.5kgf when the boom's end is in the depth of 4m under the water. 2. The hydraulic motor of the fittest kind of winder has the least leakage per time than the other kinds. 3. In the best type of several winder devices, when the pressure difference was fixed $130kg/^2$ for the safe fishery, the winding velocity of boom line was 2m/sec, is faster 0.48/sec than traditional fishing method and this winder can catch the anchovy of 1.6 tonnage. 4. As a result, the crew were decreased from 8 to 6 and the problem of heavy human power and risk on fishing operation were solved by using the this winder.

• Korean Journal of Food Science and Technology
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• v.28 no.2
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• pp.324-329
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• 1996

In order to develop a novel dewatering process for soybean milk residue, hydraulic press with ohmic heating was built and its expression conditions were examined. The electric conductivity of raw soybean milk residue was 0.128 S/m and increased linearly with increasing temperature. Water content of the residue could be reduced to 74% with the conventional hydraulic press, but to less than 70% by applying ohmic heating to the hydraulic press. The most effective dewatering was achieved by applying alternative current with 5 kHz frequency at 60 V during expression. The solid content of the expressed liauid was markedly reduced from 10% to 3.3% by ohmic heating during expression. Temperature of the cake rose to above $95^{\circ}C$ during the dewatering due to ohmic heating.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.11
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• pp.880-885
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• 2010

The Angle Ring and Cap which is called pressboard are settled at the primary and secondary coil winding of 154 kV transformer that can reduce effectively distance of insulation. As it has not manufactured pressboard of Angle Ring and Cap for high voltage grade, insulation components industry especially high voltage transformer has not participate in a competition with worldwide yet. That's why is difficult to make an specialized shape of insulation components of high voltage grade. Therefore it has finally completed to make an deformation manufacturing utility using an bellowed special analysis tools. This study that uses various analysis program determining optimum shape about insulation of Angle Ring and Cap which is related life of high voltage transformer. In addition to develop forming equipment with an specialized five steps pressing. That is also based on the mechanical strength evaluation and test, it is investigated optimized processing components.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.101-106
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• 2012

The press bulging process is very useful and productive method to produce round-type mechanical components which have not been able to be manufactured because of limitation of the conventional press technology. The application of the press bulging process has expanded very quickly in the hydraulic and electronic industry and more recently it has been used to produce other mechanical parts such as the automobile and shipping parts. This expanding application also has brought some unsolved problems and leads many researchers to put their effort into the die design of the press bulging process. In this study, to obtain the optimum die shape for the press bulging process, various process parameters have been considered such as corner radius, bulging height, pressing length, and forming load, etc. The main interest of this paper is to verify the press bulging process which has more than 4.0 in height-length ratio. From this aspect, Finite Element analysis shows great ability to simulate the precise deformation process and gives us manufacturing database. Consideration of strain, stress, and strain-rate for the various cases has been also taken to keep the forming load within a particular range.

• Journal of the Korea Safety Management & Science
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• v.16 no.2
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• pp.211-216
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• 2014

Using a high-rise building water piping after hydrostatic test of the reliability of the leak to be completed if the pressure is maintained until the leak is not commercially available considered. Due to the nature of high-rise buildings and the construction period will take several years from the lower levels of use of the water supply and fire fighting water pipe construction is in progress, the order of which I do most of the first pipe to the construction and more than three years. So kind of riser pipe is complete, install the valve in the basement by installing an automatic pump to maintain a constant pressure after hydrostatic test and after each floor plumbing piping is complete, the progress of the hydrostatic test without undergoing a separate branch pipe the valve is opened automatically when the number of the pressing pressure of the structure. I kind of do and keep working pressure of pipe until the completion of the construction work to keep the damage to human error when it is intended to prepare. In winter, the frost protection and an alternative to drainage water pipe is damaged or deformed, even if unaware of the finishing work to the building, the use of the damage caused by a leak in a after construction of finish work to be expected. Alternative to reduce this damage if the pressure test without fear of freezing to help maintain long-term commercial pressures may be considered.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.415-427
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• 2021

This technical report briefly introduced the rock cutting splitting method under development. This method is a method of excavating the rock by splitting the block after the rock cutting process. After designing the cutting geometry of the rock face, the chisel is press-fitted to remove the rock block. At this time, when the cutting block is properly designed, the tensile crack propagates smoothly at the bottom of the rock block. An analytical solution was devised to estimate the indentation force required for splitting rock blocks using fracture toughness mode 1 required for tensile crack growth. The impact force of the hydraulic breaker of the excavator was analyzed, and the grade of the excavator that can be constructed according to the rock block design geometry was analyzed.