• Plant Journal
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• v.11 no.2
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• pp.32-38
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• 2015

This study was conducted on combined cycle power plant consisting of HRSG with integral deaerator type to avoid tube failures of low pressure evaporator tubes. Based on the observation of pH variation at the discharge of boiler feed water pump by continuous pH measurement for a period of time, it was identified that pH of feed water is getting reduced as ammonia is distributed into vapor and liquid depending on the distribution ratio of ammonia in the LP drum after the deaerator. To solve this problem, the counterplan was prepared by reexamination of ammonia injection point and quantity. In conclusion, it was accomplished that 9.2~9.6 is the optimized pH range for boiler feed water by arranging additional piping for ammonia to inject directly to LP drum.

• Journal of Advanced Navigation Technology
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• v.17 no.4
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• pp.429-434
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• 2013

In this paper, the TM (Transverse Magnetic) scattering problems by a perfectly conducting strip grating over a grounded two dielectric layers with edge boundary condition are analyzed by applying the FGMM (Fourier Galerkin Moment Method). For the TM scattering problem, the induced surface current density is expected to the very high value at both edges of the strip, then the induced surface current density on the conductive strip is expanded in a series of the multiplication of the Chebyshev polynomials of the first kind and the functions of appropriate edge boundary condition. Generally, when the value of the relative permittivity of dielectric layers over the ground plane increased, the strip width according to the sharp variation points of the reflected power is shifted to a higher value. The numerical results shown the fast convergent solution and good agreement compared to those of the existing papers.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.10
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• pp.823-832
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• 2014

Displaced non-Keplerian orbit, center of mass is displaced from orbit plane, enables special spacecraft missions. It requires continuous thrust to maintain the orbit, and solar sail is useful for this purpose. Equations for feasible region and stability analysis are derived for non-Keplerian orbit for general continuous thrust. Differences for solar sail spacecraft are discussed. Non-keplerian orbits are classified into four types. Location-specific required accelerations for orbit maintenance are calculated. Orbit stabilities of each orbit type are analyzed and verified by numerical simulations. In order to control non-Keplerian orbit in unstable region, a control algorithm using the real-time LQR control is developed and evaluated by numerical simulations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.7
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• pp.709-716
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• 2013

A fan filter unit (FFU) is a device which supplies clean air from the ceiling in a clean room. With an increase in its size, velocity variation occurs within the exhaust plane and this damage the product quality or productivity. Hence, a guide vane is installed inside the device to enhance the velocity uniformity. Because the vane reduces the flow rate for a given pumping power, an optimum design is required to achieve velocity uniformity while minimizing the flow rate reduction at the same time. To find a geometry that satisfies these requirements, a series of numerical simulations has been conducted while changing the angle and length of the guide vanes. By changing the geometry of the side guide vane, the velocity uniformity increased by 3.7% and the flow rate decreased by 1.5%. For the center guide vane, the velocity uniformity increased by 2.9% and the flow rate decreased by 0.7%.

• Geotechnical Engineering
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• v.6 no.3
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• pp.65-76
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• 1990

A series of consolidated drained and untrained cubical triaxial tests were performed to investigate three dimensional strength characteristics of compressible sand. All specimens, which are formed by deposisting a fine sand loosely, were used. Failure strength in terms of effective stress analysis was greatly influenced by the variation of intermediate principal stress and so was failure criterion The adjusted effective frictional angles obtained by the stress state projected on the same octahedral plane showed almost same value, while the measured effective frictional angles showed considerable difference depending on the drainage conditions. Results of total stress analysis in undrained test turned out to fit Tresca's failure criterion well, but results of effective stress analysis turned out to fit Lade's failure criterion well.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.6
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• pp.24-34
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• 2007

Application systems that easy to access a information have been developed by IT growth and a human life variation. In this paper, we propose a application system to register a 3D footwear model using a monocular camera. In General, a human motion analysis research to body movement. However, this system research a new method to use a foot movement. This paper present a system process and show experiment results. For projection to 2D foot plane from 3D shoe model data, we construct processes that a foot tracking, a projection expression and pose estimation process. This system divide from a 2D image analysis and a 3D pose estimation. First, for a foot tracking, we propose a method that find fixing point by a foot characteristic, and propose a geometric expression to relate 2D coordinate and 3D coordinate to use a monocular camera without a camera calibration. We make a application system, and measure distance error. Then, we confirmed a registration very well.

• The korean journal of orthodontics
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• v.21 no.3
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• pp.617-634
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• 1991

The retraction of anterior teeth is one of the fundamental methods in orthodontic treatment and a proper position and angulation of anterior teeth after the retraction are very important for esthetics, stability, and function of teeth. In this research we analyzed, by Finite Element Method, the stress distribution on the periodontal ligament according to the variation of force and moment applied on the crown and predict the pattern of movement of maxillary central incisor. At the same time, the amount of force and moment caused by activation of the loop which was used for retraction of maxillary central incisor was analyzed by Finite Element Method. We observed the following results: 1) We could control the stress distribution on the periodontal ligament by proper moment/force ratio on maxillary right central incisor and predict the pattern of movement of maxillary right central incisor. 2) The amount of stress on the periodontal ligament as well as the moment/force ratio demanded by each pattern of movement increased as the destruction of alveolar bone was worse. 3) The moment/force ratio demanded by each pattern of movement decreased as the angle between the maxillary central incisor and occlusal plane decreased. 4) The force with the open loop was shown to be large compared to that with the closed loop. Also, the force with the helix decreased by 30% compared to that without the helix. 5) Under the same conditions we observed a larger moment/force ratio when the open loop and/or the helix were used.

• Journal of the Korea Convergence Society
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• v.8 no.9
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• pp.9-16
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• 2017

In this paper, sub-microwave oscillator sensor is proposed to non-invasively monitor the glucose concentration level of the human biological tissue by oscillation frequency variation. Inductive slot in the ground plane of the microstrip line is combined with the biological tissue, to realize the resonator as a part of the oscillator sensor. The phantom box mimicking the human tissue is introduced for simulation of the resonator which resonance frequency correspondingly shifts up on three step glucose concentration levels(0, 400, 800 mg/dL). Oscillator sensor circuit is fabricated as a prototype. Pig tissues instead of human is used. Oscillation frequency shift of about 14 MHz per glucose level of 400 mg/dL has been successfully measured around 1,100 MHz. This proves that the proposed sensor is applicable to a blood glucose sensor.

• Korean Journal of Plant Tissue Culture
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• v.24 no.3
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• pp.175-181
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• 1997

Plants were regenerated from hypocotyl protoplast culture of cabbage (F$_1$hybrid Green Challenger) and were transplanted on fields. The ploidy level of regenerated and seed-grown plants was measured by flow cytometry. In total 125 regenerated plant, diploid (2n), tetraploid(4n), and mixoploid (2n+4n) were 72.8%, 25.6%, and 1.6%, respectively. Most of the regenerated plants had normal phenotype, whereas several plane showed abnormal phenotype such as heavy leaf incision, savoy, and wave. The regenerated plants with abnormal phenotype and different ploidy level were analysed by isozyme and RAPD, but no significant difference was found.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.13-18
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• 1976

1) The variation of the reef knot strength $T_r$ and the trawler knot strength $T_\varrho$ with the angle $\varphi$ between the adjacent bars are given by $$T_r=T_{ro}-k_{r\varphi}$$ and $$T_\varrho=T_{{\varrho}o}+k_{\varrho\varphi}$$ where $T_{ro}$ and $T_{{\varrho}o}$ are values of $T_r$ and $T_\varrho$ at $\varphi=0^{\circ}$ respectively, and $k_r$ and $k_\varrho$ constants decided by the fibre materials of netting twines ($\varphi\;is\;0^{\circ}$ when the knot is pulled lengthwise). 2) The variation of the reef knot strength $T_r'$ and the trawler knot strength $T_\varrho'$ with the angle $\varphi'$ between any one bar and the plane made by the other three bars may be expressed by $$T_r'=T_{ro}{'}\varrho^{-c\varphi'}$$ and $$T_\varrho'=T_{{\varrho}o}{'}\varrho^{-c\varphi'}$$ where $T_{ro}{'}$ and $T_{\varrho}o{'}$ are values of $T_r{'}$ and $T_\varrho{'}$ at $\varphi'=0^{\circ}\;{(\varphi=45^{\circ})}$ respectively, and o is the coefficient of attenuation. 3) Knot strength of knotted netting may be expressed by the expression derived in the preyious paper, disregarding its shape and the direction of tensile loads acting on it.