• 한국기계연구소 소보
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• s.15
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• pp.91-103
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• 1985

In this paper, temperature distribution and thermal stress are investigated considering engine peak pressure and the time average temperature distribution in the piston under running conditions for the diesel engine. The induced stress are calculated by the Finite Element Method(FEM). The results obtained are summerized as follows. 1) The results calculated by the FEM present good agreement with other numerical solution in literature. 2) It is confirmed that maximum compressive stress are induced in the part of outside wall between the piston crown and the pin bush. 3) In the axial direction, the hoop stresses are changed its sigh at the portion of crown near the inner wall side 4)Large gradient of temperature is shown in the piston crown near the side wall in the axial direction, in the part between the piton crown and the pin bush in radical direction 5)in case of stress distribution of piston wall surface in the axial direction, the hoop stress is a little greater than axial stress, and the latter is greater than the radial stress

• Journal of Advanced Marine Engineering and Technology
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• v.9 no.2
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• pp.143-152
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• 1985

In this paper, temperature distribution and thermal stress are investigated considering engine peak pressure and the time average temperature distribution in the piston under running conditions for the marine diesel engine. The induced stress are calculated by the Finite Element Method (FEM). The results obtained are summerized as follows. 1) The results calculated by the FEM present good agreement with other numerical solution in literatures. 2) It is comfirmed that the maximum compressive stresses are induced in the part of outside wall between the piston crown and the pin bush 3) In the axial direction, the hoop stresses are changed its sign at the portion of crown near the inner wall side. 4) Large gradient of temperature is shown in the piston crown near the side wall in the axial direction, in the part between the piston crown and the pin bush in radial direction. 5) In case of stress distribution of piston wall surface in the axial direction, the hoop stress is a little greater than axial stress, and the latter is greater than the radial stress.

• ETRI Journal
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• v.32 no.3
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• pp.468-471
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• 2010

A compact square patch antenna with reconfigurable circular polarization (CP) at 2.4 GHz is proposed. Circular polarization is generated by an arc-shaped slot on the ground plane. In order to switch the CP orientation, the current flow direction of the patch is reconfigured via the PIN diodes mounted on the slot. As the slot and bias circuit are not placed on the patch side, the proposed antenna radiates a CP wave without alteration in the main beam direction. From the experimental results, the impedance and CP bandwidths of the proposed antenna have been demonstrated for up to 80 MHz and 25 MHz, respectively.

• ETRI Journal
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• v.13 no.4
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• pp.52-57
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• 1991

We fabricated very high. speed PIN Photodiode module for the application of high speed optical receiver. OMVPE was used for the growth of InP layer on InGaAs absorption layer. The structure was the combination of mesa and planartype. Fabrication procedure was more complicated than simple mesa or simple planar type structure because we used semiinsulating InP substrate in order to reduce stray capacitance. The results at-5V were as follows : dark current was less than 1nA, capacitance was 0.55pF, and cutoff frequency was above 3GHz, and rise and fall time was about 100ps.

• Journal of Information Display
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• v.12 no.2
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• pp.109-113
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• 2011

This paper summarizes the recent fabrication and characterizations of flexible high-speed radio frequency (RF) transistors, PIN-diode single-pole single-throw switches, as well as flexible inductors and capacitors, based on single-crystalline Si nanomembranes transferred on polyethylene terephthalate substrates. Flexible thin-film transistors (TFTs) on plastic substrates have reached RF operation speed with a record cut-off/maximum oscillation frequency ($f_T/f_{max}$) values of 3.8/12 GHz. PIN diode switches exhibit excellent ON/OFF behaviors at high RF frequencies. Flexible inductors and capacitors compatible with high-speed TFT fabrication show resonance frequencies ($f_{res}$) up to 9.1 and 13.5 GHz, respectively. Robust mechanical characteristics were also demonstrated with these high-frequency passives components.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.1
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• pp.50-55
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• 2020

Porcelain insulators have been used for a long time in 154 kV power transmission lines. They are likely to be exposed to sudden failure because of product deterioration. This study was conducted to evaluate the quality of porcelain insulators. After stresses were applied, the damaged regions of aged insulators were investigated in terms of chemical composition, material structure, and other properties. For porcelain insulators that were in service for a long time, the mechanical failure load was 126 kN, whereas the average mechanical failure load was 167.3 kN for new products. It was also determined that corrosion occurred at the metal pin part due to the penetration of moisture into the gap between the pin and the ceramic. Statistical analyses of failure were performed to identify the portion of the insulators that were broken. Cristobalite porcelain insulators fabricated without alumina additives had a high failure rate of 54% for the porcelain component. In the case of the addition of Alumina (Al₂O₃) to the porcelain insulators to improve the strength of the ceramic component, a more frequent damage rate of the cap and pin of 73.3% and 27%, respectively, was observed. This study reports on the material component of SiO₂ and the percentage of alumina added, with respect to the mechanical properties of porcelain insulators.

• Korean journal of food and cookery science
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• v.30 no.3
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• pp.262-270
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• 2014

This study was conducted in order to investigate the properties of bread making and quality improvement when wheat flour is replaced with whole waxy sorghum flour. Sorghum flour, which was prepared with two types of milling methods of pin mill and ultra fine pulverization, was used at different levels ranging from 10, 20 and 30%, respectively. The pasting properties of peak viscosity, setback viscosity and pasting temperature of the composite flour containing pin-milled sorghum flour were higher than those of ultra fine pulverized sorghum flour. The volumes of sorghum bread were lower than that of wheat bread; moreover, they gradually decreased with increasing amounts of sorghum flour, which has inferior dough properties and therefore collapses in the oven. The use of vital gluten (12% based on sorghum flour weight) and emulsifier (SSL; sodium stearoyl lactylate) increased the extensibility and resistance to the extension of the dough, thereby improving its rheological properties. Thus, the oven spring of bread containing sorghum was improved, demonstrating as loaf volume increase up to 15%. However, in the case of breads containing 30% sorghum flour, the loaf volumes were still unacceptably low. Therefore, the formula and the bread making process were further modified as follows: An increase of vital gluten ($12%{\rightarrow}18%$) and shortening ($3%{\rightarrow}6%$), a decrease of mixing time and dough fermentation temperature, and the addition of sorghum flour after gluten development during mixing. The above modifications resulted in the improvement of sorghum bread quality. Therefore, we suggest that pin-milled sorghum flour is more appropriate than ultra fine pulverized sorghum flour for making bread.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.12
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• pp.2503-2510
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• 2015

This paper presents a single-phase energy measurement IC to measure electric power quantities. The entire IC includes two programmable gain amplifiers (PGAs), two ${\sum}{\Delta}$ modulators, a reference circuit, a low-dropout (LDO) regulator, a temperature sensor, a filter unit, a computation engine, a calibration control unit, registers, and an external interface block. The proposed energy measurement IC is fabricated with $0.18-{\mu}m$ CMOS technology and housed in a 32-pin quad-flat no-leads (QFN) package. It operates at a clock speed of 4,096 kHz and consumes 10 mW in 3.3 V supply.

• Imaging Science in Dentistry
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• v.43 no.3
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• pp.191-196
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• 2013

Purpose: This study assessed the accuracy of linear and angular measurements on panoramic radiographs taken at different positions in vitro. Materials and Methods: Two acrylic models were fabricated from a cast with normal occlusion. Straight and $75^{\circ}$ mesially and lingually angulated pins were placed, and standardized panoramic radiographs were taken at standard position, at an $8^{\circ}$ downward tilt of the occlusal plane compared to the standard position, at an $8^{\circ}$ upward tilt of the anterior occlusal plane, and at a $10^{\circ}$ downward tilt of the right and left sides of the model. On the radiographs, the length of the pins above (crown) and below (root) the occlusal plane, total pin length, crown-to-root ratio, and angulation of pins relative to the occlusal plane were calculated. The data were subjected to repeated measures ANOVA and LSD multiple comparisons tests. Results: Significant differences were noted between the radiographic measurements and true values in different positions on both models with linear (P<0.001) and those with angulated pins (P<0.005). No statistically significant differences were observed between the angular measurements and baselines of the natural head posture at different positions for the linear and angulated pins. Conclusion: Angular measurements on panoramic radiographs were sufficiently accurate and changes in the position of the occlusal plane equal to or less than $10^{\circ}$ had no significant effect on them. Some variations could exist in the pin positioning (head positioning), and they were tolerable while taking panoramic radiographs. Linear measurements showed the least errors in the standard position and $8^{\circ}$ upward tilt of the anterior part of the occlusal plane compared to other positions.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.121-126
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• 2015

This paper proposes a novel reconfigurable microstrip antenna based on alternating a perturbation structure to achieve circular polarization diversity. The proposed antenna consists of an annular ring microstrip radiator for simultaneously loading stub and slot perturbations which support right- and left-handed circular polarization senses and two PIN diodes for choosing the operating polarization sense. By controlling the states of two PIN diodes between perturbing slot and stub at one diagonal corner of the radiator, reconfigurable circular polarization senses of the proposed antenna are successfully obtained and alternated. The proposed antenna has been theoretically analyzed and experimentally demonstrated at 2.4 GHz of S-band for satellite communication system. The simulation and measurement results of the proposed antenna show in good agreement with the reflection coefficients, axial-ratios, realized antenna gains, and radiation patterns.