• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.2
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• pp.1-7
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• 2008

To improve the performance of the bent axis type axial piston pump driven by the tapered piston, it is necessary to know the driving characteristics and mechanism of the tapered piston and the cylinder block. Since each piston not only rotates on its axis and reciprocates in the cylinder bore, but also revolves around the axis of the driving shaft, it is difficult to analyze the driving mechanism theoretically. The theoretical mechanism far the bent axis type axial piston pump is studied by using the geometrical method. The driving range of the tapered piston is determined by theoretical equations. The results show that the cylinder block is driven by one tapered piston in a limited range and the core parameters such as driving factor of the piston and the ahead delay angle influenced performance of the bent axis type axial piston pump.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.2
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• pp.223-231
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• 1997

A variety of approaches have been investigated for the application of spark-ignition engine knock control. The control method implemented, here as "Fuzzy Control", has the advantage of not requiring the knowledge of a mathematical model of the controlled object and is more robust and flexible than conventional approaches. Knock control in this study is performed using vibration signal which is measured with accelerometer attached to the cylinder block of a 1498cc four-cylinder spark-ignition engine. The experimental results obtained with this method are compared with those obtained with a knock interval controller and with those of a conventional controller. Those results illustrate better performance in torque than knock interval controller and conventional controller.ontroller.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.2
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• pp.252-257
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• 2011

Magnesium thin films for marine engine parts such as the engine block and the cylinder head cover etc. were prepared on the magnesium alloy(AZ91D) substrate by Thermo-electron activated Ion-plating method. The influence of gas pressure and substrate bias voltages on the crystal orientation and morphology of the films was investigated with X-ray diffraction and field emission scanning electron microscope(FE-SEM), respectively. Moreover, the effect of crystal orientation and morphology of the magnesium films on the its hardness property was investigated as well. From the results, the hardness of the films was increased in Ar gas pressure due to the grain boundary strengthening and occlusion effects.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.4
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• pp.39-48
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• 2005

Finite element analyses have been performed for the purpose of obtaining the robust and reliable design of engine cylinder block. Fatigue under high cycle operating loads is a primary concern and is evaluated by a probabilistic method. The robust and reliable design by a probabilistic method can provide satisfactory design conditions for the performance of the system under the influence of noise factors. Therefore, the design by this method will be desensitized to the uncontrollable noise factors. The simple methodology evaluates the distortion of main bore is proposed for the purpose of maintaining a well-controlled clearance between the crankshaft and main bores. The proposed methodology has proven a capability of predicting the distortion of the main bore under assembly, thermal, and firing loads. The calculated results are correlated well with the experimental ones.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.4_2
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• pp.649-656
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• 2023

Recently, global warming has become severe, and regulation is established for carbon savings each field. its regulation is applied to various fields using IC engine such as automobile, ship, agricultural machine. Therefore engine block applied Common Rail Direct Injection(CRDI) technology, that carry out thermal-structure analysis to examine design. The thermal load about 900℃ by explosion was applied in cylinder. And pressure about 9 MPa(90 Bar) was applied to structure analysis. As a result, it was the highest at 185.99℃ at the top of cylinder. Static-structure analysis applied thermal load, that was shown maximum equivalent stress at 142.59 Mpa and Maximum principal stress 145.03 MPa, Minimum principal stress -149 MPa. When compare analysis results to material property, it design is safety structurally.

• Tunnel and Underground Space
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• v.21 no.3
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• pp.181-191
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• 2011

It is very difficult to prepare a lab. test specimen from weak rock masses affected by faults, highly fractured zone or weathered zone. In conventional method of in situ direct shear test a rock block is sheared inside galleries, where reactions for the hydraulic jacks are available. A new in situ direct shear test apparatus has been developed in this study to perform the test inside galleries as well as open pit conditions. The apparatus is composed of normal and shear reaction plates including load transfer plates, hydraulic cylinder systems, load cells, multistage shear boxes with fixing devices, and needle rollers. Maximum size of the test block is $400{\times}400{\times}460$ mm, and procedures of the test block preparation has been suggested. To explore the field applicability of in situ direct shear test apparatus, proper test block site was investigated by extensive geological field survey. In situ direct shear test has been successful in producing most of information related to strength and deformability of the weak rock.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.3 s.40
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• pp.13-17
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• 2006

Dense and periodic arrays of holes and tungsten none dots were fabricated on silicon oxide and silicon. The holes were approximately 25 nm wide, 40 nm deep, and 60 nm apart. To obtain nano-size patterns, self-assembling resists were used to produce layer of hexagonally ordered parallel cylinders of polymethylmethacrylate(PMMA) in polystyrene(PS) matrix. The PMMA cylinders were degraded and removed with acetic acid rinse to produce a PS mask for pattern transfer. The silicon oxide was removed by fluorine-based reactive ion etching(RIE). Selectively deposited tungsten nano dots were formed inside nano-sized trench by using a low pressure chemical vapor deposition(LPCVD) method. Tungsten nano dot and trenched silicon sizes were 26 nm and 30 nm, respectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.6
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• pp.1-6
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• 2002

Micro engine that includes Micro scale combustor is fabricated. Design target was focused on the observation of combustion driven actuation in MEMS scale. Combustor design parameters are somewhat less than the size recommended by feasibility test. The engine structure is fabricated by isotropic etching of the photosensitive glass wafers. Electrode is formed by electroplating of the Nickel. Photosensitive glass can be etched isotropically with almost vertical angle. Bonding and assembly of structured photosensitive glass wafer from the engine. Combustor size was determined to be 1mn scale. Piston in cylinder moves by fuel injection and reaction. In firing test, adequate engine operation including ignition, flame propagation and piston motion was observed. Present study warrants further application research on MEMS scale internal combustion power units.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.205-210
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• 2006

The impact forces of the highly nonlinear waves are one of the important factors in designing the ocean structures. The impact forces are very difficult to analyze numerically and experimentally because they are impulsive in magnitude and occur instantaneously. In this study the numerical program based on N.S. equations are used to investigate the impact forces of steep waves where the waves are gene rated by the wave maker in the numerical wave basin. The arbitrary steep waves are generated by the superposition of waves of single frequency and the impact forces on vertical cylinder are simulated on the multiblock grids. V.O.F. and the local height function methods are used to track the free surfaces. To validate the numerical analysis the numerical results are compared with the experimental ones and the acceptable agreements are found. It is thought that more studies on the simulations of the incoming breaking waves and the impact forces on the vertical cylinder should be made to obtain the useful results to be applied in the offshore design.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.2 s.43
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• pp.17-21
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• 2007

Dense and periodic arrays of holes and Si nano dots were fabricated on silicon substrate. The nanopatterned holes were approximately $15{\sim}40nm$ wide, 40 nm deep and $40{\sim}80\;nm$ apart. To obtain nano-size patterns, self?assembling diblock copolymer were used to produce layer of hexagonaly ordered parallel cylinders of polymethylmethacrylate (PMMA) in polystyrene(PS) matrix. The PMMA cylinders were degraded and removed with acetic acid rinse to produce a PS. $100\;{\AA}-thick$ Au thin film was deposited by using e-beam evaporator. PS template was removed by lift-off process. Arrays of Au nano dots were transferred by using Fluorine-based reactive ion etching(RE). Au nano dots were removed by sulfuric acid. Si nano dots size and height were $30{\sim}70\;nm$ and $10{\sim}20\;nm$ respectively.