• Journal of the Society of Naval Architects of Korea
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• v.36 no.3
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• pp.134-143
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• 1999

The ship's bows and sterns are assembled with the curved blocks. In shipyards, the roller bending and the line heating or others are being used to fabricate such doubly curved shell. Firstly, the cylinder- or cone-type is formed through the roller bending, and then, the line heating is implemented to form the rest. This paper presents an algorithm to determine the direction for the roller bending and the shape to be formed as fabrication information. The direction for the roller bending is determined with Gauss mapping of the desired surface and the shape to form is calculated by comparing the bent shape with the desired shape.

• Publications of The Korean Astronomical Society
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• v.18 no.1
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• pp.87-95
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• 2003

FIMS (Far-ultraviolet IMaging Spectrograph) is the main payload of STSAT-1 satellite which was successfully launched on September 27, 2003. The optical system of FIMS consists of two sets of parabolic cylinder mirror, slit, ellipsoidal reflection grating, and baffle system. We designed two types of baffle system for the FIMS: FOV baffle and order baffle. FOV baffle in the mirror house controls the field of view, and the order baffle in the vacuum box blocks the rays reflected rays by different orders.

• Journal of Welding and Joining
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• v.32 no.5
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• pp.65-71
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• 2014

Atmospheric plasma spraying (APS) is world-widely used process in the automotive industry as a method to provide wear resistance coatings for engine cylinder bore, using various materials. The weight of engine blocks can be considerably decreased by removing cast iron liners, which can finally result in the improvement of fuel efficiency. In this study, five kinds of powder materials, 1.2C steel powder and 1.2C steel powder mixed with 5, 10, 15, 20 wt.%. molybdenum powder, were deposited by atmospheric plasma spraying in order to investigate the effect of molybdenum on the wear resistance of coatings. Microstructural analysis showed that molybdenum splats were well distributed in 1.2C steel matrix with intimate bonding. The molybdenum added coatings showed better tribological properties than 1.2C steel coating. However, above the 15 wt.%. blending fraction, wear resistance was somewhat degraded with poor roughness of worn surface due to the brittle fracture occurred in molybdenum splats. Consequently, compared to conventional liner material, gray cast iron, 10 wt. pct. molybdenum blended 1.2C steel coating showed much better tribological properties and therefore it looks very feasible to replace gray cast iron liner.

• ALGAE
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• v.25 no.1
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• pp.37-44
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• 2010

A tide-simulating apparatus was developed for culturing marine macroalgae. The objective of this study was to introduce a novel tide-simulating apparatus that can simulate a diurnal or semi-diurnal tidal cycle in the laboratory. In this apparatus, the seaweeds are move up and down and the water level remains the same during the simulated tidal cycle. The apparatus consists of 18 cylindrical culture tanks (3 blocks $\times$ 6 culture tanks) with 12 cm diameter and 24.5 cm long containing up to 2.5 L of seawater. There is a horizontal plate which covered all 18 culture tanks, and it is raised and lowered by a programmable motor that can regulate exposure time. In one application, seaweeds are attached to braided twine hung on Plexiglas air-tubing. The air-tubing is attached to a lid that is set on a horizontal plate. This apparatus is made of colorless Plexiglas to maximize light transmittance. This apparatus is easily disassembled and transportable to any indoor laboratory, wet laboratory, greenhouse, etc. This apparatus also offers considerable flexibility in terms of design. The size of culture tank can be redesigned by either increasing the height of cylinder or/and using a different diameter of cylindrical Plexiglas, therefore, larger/taller thalli can be cultivated. Growth rates of three eulittoral Porphyra species from different tidal elevations have been compared using this device.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.1
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• pp.26-34
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• 2008

This paper summarizes a design procedure of radiated noise from engine blocks of marine engines. This air-borne noise is one of the significant noise contributors including the aeroacoustic noise due to intake and exhaust and the re-radiation due to structure-borne noise. Excitation forces by engine operations are evaluated taking into account the power generation mechanism from the burning process to the subsequence motion of internal parts; piston, connecting rod, and crank shaft. The acoustic transfer vector method is incorporated to effectively simulate the radiated noise field under the various operation conditions. A contribution analysis for the various excitations to the radiated noise is conducted. It is found that the firing pressure is the main source of the radiated noise, and so the structure of the cylinder can be modified to significantly reduce the radiated noise from the engine block.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.1
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• pp.14-22
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• 2010

Hybrid Electronic Vehicle (HEV) is one of the solutions of high oil price and environment problem. Recently, study of HEV is important for automobile industry. However HEV has a lot of components and there are many cases for assembling, it's impossible to test results from assembling by using real vehicles. To solve this problem, hybrid system simulator is required. The purpose of this study is to develop and optimize of engine module for hybrid system simulator. The commercial 1-D engine simulation program, WAVE is used to get the engine capacity and performance data and 1-D simulation model of base engine is compared with engine experiment results. Using the data, the engine module is developed based on the MATLAB Simulink. There are blocks of base engine, Single-CVVT engine and Dual-CVVT engine. The effect of acceleration and deceleration is applied to each engine block. In addition, the control and processing logics for CIS technology are developed. Finally the simulator operates FTP-72 mode test.

• Smart Structures and Systems
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• v.26 no.5
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• pp.657-666
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• 2020

A rotational pulse-echo ultrasonic propagation imager that can inspect cylindrical specimens for material nondestructive evaluations is proposed herein. In this system, a laser-generated ultrasonic bulk wave is used for inspection, which enables a clear visualization of subsurface defects with a precise reproduction of the damage shape and size. The ultrasonic waves are generated by a Q-switched laser that impinges on the outer surface of the specimen walls. The generated waves travel through the walls and their echo is detected by a Laser Doppler Vibrometer (LDV) at the same point. To obtain the optimal Signal-to-Noise Ratio (SNR) of the measured signal, the LDV requires the sensed surface to be at a right angle to the laser beam and at a predefined constant standoff distance from the laser head. For flat specimens, these constraints can be easily satisfied by performing a raster scan using a dual-axis linear stage. However, this arrangement cannot be used for cylindrical specimens owing to their curved nature. To inspect the cylindrical specimens, a circular scan technology is newly proposed for pulse-echo laser ultrasound. A rotational stage is coupled with a single-axis linear stage to inspect the desired area of the specimen. This system arrangement ensures that the standoff distance and beam incidence angle are maintained while the cylindrical specimen is being inspected. This enables the inspection of a curved specimen while maintaining the optimal SNR. The measurement result is displayed in parallel with the on-going inspection. The inspection data used in scanning are mapped from rotational coordinates to linear coordinates for visualization and post-processing of results. A graphical user interface software is implemented in C++ using a QT framework and controls all the individual blocks of the system and implements the necessary image processing, scan calculations, data acquisition, signal processing and result visualization.

• Applied Microscopy
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• v.25 no.1
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• pp.1-14
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• 1995

The purpose of this study was to investigate the main sensory trigeminal nucleus in the aging rat brain by means of electron microscope. Male Sprague-Dawley rats, two (control group) and thirty six (aging group) months of age, were used. These animals were sacrificed by perfusion fixation with 2.5% glutaraldehyde-2.0% paraformaldehyde (0.1M phosphate buffer, pH 7.4) under sodium pentobarbital. The objective area was punched out with a sharp-edged metal cylinder of 0.8 mm in diameter. These blocks of tissue were then washed in 0.1M phosphate buffer, postfixed in 2% osmium tetroxide, dehydrated in a graded series of ethyl alcohol, and embedded in Epon 812. Thin sections were cut with Super Nova ultramicrotome, pick up on grids and double stained with lead citrate and uranyl acetate, and observed in JEOL 100B electron microscope. The results were as follows: 1. In the control group, the neuronal cell body of the main sensory trigeminal nucleus was filled with nucleus, Golgi complex, Nissl substance, mitochondria, microfilaments and microtubules. However, few Nissl substances are seen in neuronal cell body. Axoaxonic synapse, axodendritic synapse, axosomatic synapse, axospinous synapse, myelinated and unmyelinated nerve fibers were well organized around cell bodies. Neurons with abnormal changes were not seen. 2. In the aging group, the neuronal cell body of the main sensory trigeminal nucleus contained large number of lipofuscin granules, dense body and swollen mitochondria. Terminal boutons contained glycogen, crystal-like vesicle and membranous indicating first signs of degeneration. The dendrites were found to be in synaptic contact with altered axon terminals. Frequently axons filled with dark axoplasn and splitted myelin sheath were noticed.

• Journal of Technologic Dentistry
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• v.38 no.3
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• pp.135-142
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• 2016

Purpose: The aim of this research was to evaluate the influence of different surface treatments on the shear bond strength of zirconia ceramic to composite resin. Methods: Seventy two cylinder-shape (diameter: 5 mm; height: 12 mm) blocks of experimental industrially manufactured Y-TZP ceramic were abraded with $125{\mu}m\;Al_2O_3$ particles and randomly divided into 4 groups. All the materials were categorized as group Gc(control group - composite resin veneering on zirconia surface), Gr - composite resin veneering after surface treatment of Rocatec system (3M ESPE, Seefeld, Germany) group; Gz - composite resin veneering after surface treatment of Zirconia primer (Z-primer, Bisco, U.S.A) group; Gm - composite resin veneering after surface treatment of zirconia primer (Monobond plus, ivoclar vivadent AG, Liechtenstein) group. Two different zirconia primers and Rocatec system were used to zirconia cylinders (n=16) onto the zirconia surface. Zirconia specimens, polished and roughened, were pretreated and composite bilayer cylinders bonded using conventional adhesive techniques. Results: Shear bond strengths were analyzed using single-factor ANOVA(p<0.05). Bond strength values achieved after airbone particle abrasion and zirconia surface pre-treatments(p<0.05). Conclusion: Shear bond strength tests denmonstrated that zirconia primer is a viable method to improved bond strength between zirconia ceramic core and veneering composites.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.10
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• pp.921-927
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• 2012

In this paper we deal with a hydraulic tilting actuator to make a diagnosis of load characteristic acting on the tilting actuator of the tilting train. Tilting actuator in the tilting train plays a role of making tilt of the train when the train runs a curve section to make the train run without deceleration. However in the process of tilt the tilting actuator is affected by the load acting on the actuator, which has a possibility to make bogie vibration. In order to figure out the effect of the load on the tilting actuator a hydraulic tilting devices that are capable of tilting the train is proposed. The proposed devices are installed in the front bogie and in the rear bogie to make tilting of the train. The devices are consist of sensors that measure the load capacity of the actuator and displacement of the hydraulic cylinder stroke, control blocks to make synchronization of the two actuators, user interface block to monitor the status of the actuators. The effectiveness of the proposed hydraulic tilting actuators is presented by the experimental evaluation using actual tilting train.