Jung Min Woo;Hwang Chang Mo;Jeong Gi Seok;Kang Jung Soo;Ahn Chi Bum;Kim Kyung Hyun;Lee Jung Joo;Park Yong Doo;Sun Kyung
Journal of Biomedical Engineering Research
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v.26
no.6
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pp.393-398
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2005
An electromechanical type is the most useful mechanism in the various pumping mechanisms. It, however, requires a movement converting system including a ball screw, a helical cam, or a solenoid-beam spring, which makes the device complex and may lessen reliability. Thus, the authors have hypothesized that an electromagnetic actuator mechanism can eliminate the movement converting system and that thereby enhance the mechanical reliability and operative simplicity of an electropneumatic pump. The purpose of this study was to show a novel application of electromagnetic actuator mechanism in pulsatile pump and to provide preliminary data for further evaluations. The electromagnetic actuator consists of stators with a single winding excitation coil and movers with a high energy density neodymium-iron-boron permanent magnet. A 0.5mm diameter wire was used for the excitation coil, and 1000 turns were wound onto the stators core with parallel. A prototype of extracorporeal electro-pneumatic pump was constructed, and the pump performance tests were performed using a mock system to evaluate the efficiency of the electromagnetic actuator mechanism. When forward and backward electric currents were supplied to the excitation coil, the mover effectively moved back and forth. The nominal stroke length of the actuator was 10mm. The actuator dimension was 120mm in diameter and 65mm in height with a mass of 1.4kg. The prototype pump unit was 150mm in diameter, 150mm in thickness and 4.5kg in weight. The maximum force output was 70N at input current of 4.5A and the maximum pump rate was 150 beats per minute. The maximum output was 2.0 L/minute at a rate of 80bpm when the afterload was 100mmHg. The electromagnetic actuator mechanism was successfully applied to construct the prototype of extracorporeal electropneumatic pump. The authors provide the above results as a preliminary data for further studies.
This study was conducted to investigate the effect on agricultural environment and crop productivity by different amount of applied fertilizer in consideration of irrigation water quality. N, P and K contents of irrigation water used in this experiment were 6.16, 0.26 and 9.37 mg/L, respectively. N, P and K Concentrations of runoff water were lower than those of inflow water during rice cultivation. N, P and K Concentrations of ponded and percolated water were changed according to the amount and time of applied fertilization. During rice cultivation in paddy soil, nitrogen balance was closed to 0 in SFT 50% (50% level of soil testing fertilization), 0.14 kg/ha, but it was 95.3 kg/ha in CF (conventional fertilization) treatment In SW 50% and STF (soil testing fertilization) treatment yield of perfect rice was not greatly different as compared with CF treatment due to the superiority of ripening rate, 1,000 grains weight and milling characteristics. Mechanical paratability of rice was excellent in NF (non fertilization) treatment, STF 50% treatment showed higher in nutrient availability and fertilizers use efficiency than other treatments.
Kim, Dae-Kuk;Kim, Kyo-Tae;Park, Jeong-Eun;Hong, Ju-Yeon;Kim, Jin-Seon;Oh, Kyung-Min;Nam, Sang-Hee
Journal of the Korean Society of Radiology
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v.9
no.2
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pp.67-72
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2015
In diagnostic radiology, the use of automatic exposure control device is internationally recommended for diagnosis and optimization. However, if exposed to prolonged radiation is a complicated manufacturing process, there is a problem that occurs decrease of various performance overall brightness sensor, which is commercially available conventional. Therefore, in this study, absorption of X-ray is high, and I want to evaluate the AEC applicability of the sensor of the photoconductor-based production has an easy advantage. Experimental results confirms the possibility of fabrication of the sensor through an increase in the SNR, with the detection efficiency superior, accurate turn-off. In addition, it is confirmed that the experimental results of the transmittance and the latent image, Ghost effect by the light conductor does not appear, in the case of a photoconductor with the exception of the PbO, 80% - and it was confirmed good transmittance of 90%. Therefore, excellent mechanical stability and poor performance due to a change of the doping concentration than the existing products that have been put to practical use, the sensor easy photoconductor based, fabrication and can be applied as AEC sensor is expected.
Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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2011.10a
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pp.39-41
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2011
The recycling rate of recovered paper in Korea is the highest in the world, 92%, but remanufacturing yield is low due to the extremely poor quality of the paper. The poor quality, in turn, influences to the reject amount in deinking process. To increase the yield of old newspaper recycling process, hydrophobic degree of inorganic pigments of deinking stock must be reduced. To determine the hydrophobicity, Pitch Potential Deposit Tester (PDT) was newly designed and applied with respect to the SB latex property of various quality used in Korea; its hydrophobic degree according to Tg, gel content, charge and particle size of latex and optimum designing condition of SB latex. And below are the conclusions: 1. The reason of excessive reject from old newspaper deinking process for total amount of printed ink is loss of inorganic pigments. When lipase, a biochemical catalyst, was applied with the purpose of preventing inorganic pigments loss about more than 70% of total reject weight and promoting hydration of pulp for deinking, deinking process yield of pre flotation secondary stage increased remarkably without any changes of deinking efficiency. 2. Lipase improved deinking stock by cutting ester linkage on surface of hydrophobic materials to promote its hydration. From this, it reached the conclusion that hydration degree of stock exercises significant effect on flotation deinking process yield. 3. Inorganic alkali promotes hydration of deinking stock. But there have been needs for more fundamental measures other than inorganic alkali of promoting hydration for yield improvement. For this, this study intended to find out reasons of chemical properties change on surface of hydrophobic material by change of pH. 4. Pitch Deposit Test (PDT) was performed for understanding principle of why surface of coating flake from OMG is hydrophobic and why it becomes hydrophilic when pH of stock is alkaline. As a result of this test, it is determined that swelling property by change of pH of latex film, which were used as coating adhesive is the reason for hydrophobic change. 5. Hydrophilicity of coating flake increased with hydrophilic pigments. And as more of SB Latex adhesive was used and higher of calcium hardness of stock became, its hydrophilicity decreased. SB Latex adhesive film is reformed by mechanical friction. For having hydrophilicity under neutral pH, strong bruising action such as kneading is required. 6. Because swelling of adhesive film decreases as Tg of SB latex gets lower and mean diameter gets smaller, it shows hydrophobicity under neutral pH. This lowers hydrophilicity of coating flake, which leads to easy elimination with flotation reject on DIP process. Therefore, for improving future flotation yield, it is necessary to develop to use eco-friendly clean SB latex by raising Tg and increasing mean diameter for recycling, and as a result, to reduce excessive loss of coating flake as a reject from deinking process.
Kim, Junghee;Cho, Sungho;Lee, Choongho;Han, Jaewoong;Hwang, Heon
Journal of Biosystems Engineering
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v.38
no.2
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pp.138-148
/
2013
Purpose: Determining an appropriate path is a top priority in order for a robot to maneuver in a dynamically efficient way especially in a pick-and-place task. In a non-standardized work environment, current robot arm executes its motion based on the kinematic displacements of joint variables, though resulting motion is not dynamically optimal. In this research we suggest analyzing and applying motion patterns of the human arm as an alternative to perform near optimum motion trajectory for arbitrary pick-and-place tasks. Methods: Since the motion of a human arm is very complicated and diverse, it was simplified into two links: one from the shoulder to the elbow, and the other from the elbow to the hand. Motion patterns were then divided into horizontal and vertical components and further analyzed using kinematic and dynamic methods. The kinematic analysis was performed based on the D-H parameters and the dynamic analysis was carried out to calculate various parameters such as velocity, acceleration, torque, and energy using the Newton-Euler equation of motion and Lagrange's equation. In an attempt to assess the efficacy of the analyzed human motion pattern it was compared to the virtual motion pattern created by the joint interpolation method. Results: To demonstrate the efficacy of the human arm motion mechanical and dynamical analyses were performed, followed by the comparison with the virtual robot motion path that was created by the joint interpolation method. Consequently, the human arm was observed to be in motion while the elbow was bent. In return this contributed to the increase of the manipulability and decrease of gravity and torque being exerted on the elbow. In addition, the energy required for the motion decreased. Such phenomenon was more apparent under vertical motion than horizontal motion patterns, and in shorter paths than in longer ones. Thus, one can minimize the abrasion of joints by lowering the stress applied to the bones, muscles, and joints. From the perspectives of energy and durability, the robot arm will be able to utilize its motor most effectively by adopting the motion pattern of human arm. Conclusions: By applying the motion pattern of human arm to the robot arm motion, increase in efficiency and durability is expected, which will eventually produce robots capable of moving in an energy-efficient manner.
In order to overcome these disadvantages, the halogen light source, which was previously used as a vehicle fog light, has increased power consumption and a short lifetime, and thus, an automobile light source is gradually being replaced with an LED. However, when the vehicle LED fog light is turned on, there is a disadvantage in reducing the life of the fog lamp due to the high heat generated from the LED. The heat generated by the LED inside the fog lamp is mainly emitted by the heatsink, but most of the remaining heat is released to the outside through convection. When cooling efficiency decreases due to convection, thermal energy generates heat to lenses, reflectors, and bezels, which are the main parts of lamps, or generates high temperatures in LED, thereby shortening the life of LED fog lights. In this study, we tried to improve the heat dissipation performance by convection in addition to the heat dissipation method by heat sink, and to determine the installation location of vents that can discharge the internal air or intake the external air of LED fog lamp for vehicle. Thermal fluid analysis was performed to ensure that the optimal data were reflected in the design. The average velocity of air increased in the order of Case3 and Case2 compared to Case1, which is the existing prototype, and the increase rate of Case3 was relatively higher than that of other cases. This is because the vents installed above and below the fog lamps induce the convective phenomena generated according to the temperature difference, and the heat is efficiently discharged with the increase of the air speed.
Kim, Jang-Ho Jay;Park, Joon-Hong;Choi, Sung-Uk;Heo, Jun-Haeng;Han, Kyong-Hee
Journal of Engineering Education Research
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v.13
no.6
/
pp.152-163
/
2010
Civil engineering based on construction and maintenance of infrastructures for social and human development, it has a conservative aspects to adopt the high-technology and pace of change from ancient society. Therefore, the education of civil engineering consists of very similar contents from the past until now. Also, civil engineering, area is established the infrastructure widely included structure, geotechnical, hydraulic, environmental, surveying, construction management. Civil engineering have totally difference characteristics compared to manufacturing industry field for market interests such as mechanical engineering, chemical engineering, material engineering etc. Therefore, the capstone design concepts of civil engineering for public interests must be changed and applied unlike any other engineering areas capstone design. In this paper, the modified capstone design contents and instruction in civil engineering of Yonsei University is informed and evaluated using undergraduate students' course evaluations and learning assessment to verify the efficiency of modified capstone design in civil engineering.
Jung, Yeon-Hee;Park, So-Jin;Seo, Bum-Kyoung;Lee, Kune Woo;Han, Myeong-Jin
Applied Chemistry for Engineering
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v.17
no.6
/
pp.604-608
/
2006
Polymer composites for measuring the radioactive contamination are prepared by coating ZnS(Ag) powders as a scintillator on polysulfone base layer. The composites consist of the active layer for a scintillation reaction with radioactive wastes and the transparent support layer for transmittance of light photons emitted by scintillation in the active layer. The binding of the active layer, including ZnS(Ag), on the support layer is proceeded via coating with polysulfone as a binder, without any extra adhesive. The coating was obtained by either casting via a Doctor Blade as applicator or screen printing. The prepared composites feature a monolithic structure, resulting in the complete adhesion between two layers. The composite prepared by the casting technique using an applicator holds a good detection efficiency in measuring the alpha radionuclide, but its structure becomes fragile because of warping in morphology. On the contrary, the composite prepared by the screen printing shows a good detection capacity as well as a good stability in a mechanical shape.
In this study, SiC whiskers were grown in porous alumina substrate in order to enhance the filtering efficiency, performance, and durability by controlling pore morphology. This experiment was performed by Chemical Vapor Infiltration (CVI) in order to obtain the whiskers on the inside of pores as well as on the surface of porous the A1$_2$O$_3$ substrate. The deposition behavior was changed remarkably with the deposition position, temperature, and input gas ratio. First, the mean diameter of whisker was decreased as the position of observation moved into the inside of substrate due to the reactant gas depletion effect'. Second, the deposition temperature caused the changes of the deposition type such as debris, whiskers and films and the change in morphology affect the various properties. When SiC films were deposited. the gas permeability and the specific surface area decreased. However, the whisker showed the opposite result. The whiskers increase not only the specific surface area and minimizing pressure drop but also mechanical strength. Therefore it is expected that the porous alumina body which deposited the SiC whisker is the promising material for the filter trapping the particles.
The Journal of Korean Institute of Electromagnetic Engineering and Science
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v.13
no.10
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pp.1089-1097
/
2002
In this paper, the novel shipboard Active Phased Array Antenna(APAA) system for maritime mobile satellite communications is introduced. The antenna uses novel technologies like wide range hybrid tracking, single antenna elements with both of Rx and Tx, asymmetrical array structure, interference isolation between Rx and Tx, and error correction method from frequency scan effect. The antenna has single aperture for both of Rx and Tx with 32 $\times$ 4 two-dimensional array. The antenna has two beams. Its frequencies are 7.25 ~ 7.75 GHz for Rx and 7.9 ~ 8.4 GHz for Tx. The antenna gains are 35.4 dBi for Rx and 35.7 dBi for Tx, those are 54 % of efficiency. The electrically steering ranges are $\pm$35$^{\circ}$ of elevation direction and $\pm$4$^{\circ}$ of azimuth direction. The mechanical control ranges at hybrid tracking capability are continuous 360$^{\circ}$ of azimuth direction and $\pm$10$^{\circ}$ of elevation direction. The antenna has 2.2$^{\circ}$ of 3 dB beamwidth, -14 dB of sidelobe level, and 21 dB of cross-pol suppression. The antenna performance was measured by near field measurement set. Its system performance was tested on the ship motion simulator and with the satellite transponder simulator. The test result showed that its tracking error was within -3 dB from its peak gain under motion condition. The antenna system was tested by real modulated Direct Broadcasting Satellite(DBS) signals to check its communication processing function.
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