• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.11
• /
• pp.70-75
• /
• 2006

The cabin pressurization system response should be consistent with the design limits such as the cabin pressure schedule, the pressure regulation tolerance, the maximum rate of pressure change during normal and abnormal operation and the maximum cabin air inflow rate change. In this paper, the results of pressure loss analysis and flight test for cabin pressurization system of T-50 advanced trainer are introduced. The pressure tolerance at unpressurized condition using calculated exit area of pressurization components through pressure loss analysis is predicted. Pressurization components of D company are selected and the predicted pressure tolerance is in good agreement with flight test results. Finally, T-50 pressurization system is verified by some flight tests of T-50 advanced trainer to comply with various pressurization design criteria of MIL-E-18927.

• International Journal of Aeronautical and Space Sciences
• /
• v.14 no.2
• /
• pp.122-132
• /
• 2013

In this research the development of unstructured grid discretization solution techniques is presented. The purpose is to describe such a conservative discretization scheme applied for experimental validation work. The objective of this paper is to better establish the effects of mesh generation techniques on velocity fields and particle deposition patterns to determine the optimal aerodynamic characteristics. In order to achieve the objective, the mesh surface discretization approaches used the VLA prototype manufacturing tolerance zone of the outer surface. There were 3 schemes for this discretization study implementation. They are solver validation, grid convergence study and surface tolerance study. A solver validation work was implemented for the simple 2D and 3D model to get the optimum solver for the VLA model. A grid convergence study was also conducted with a different growth factor and cell spacing, the amount of mesh can be controlled. With several amount of mesh we can get the converged amount of mesh compared to experimental data. The density around surface model can be calculated by controlling the number of element in every important and sensitive surface area of the model. The solver validation work result provided the optimum solver to employ in the VLA model analysis calculation. The convergence study approach result indicated that the aerodynamic trend characteristic was captured smooth enough compared with the experimental data. During the surface tolerance scheme, it could catch the aerodynamics data of the experiment data. The discretization studies made the validation work more efficient way to achieve the purpose of this paper.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.40 no.4
• /
• pp.127-134
• /
• 2012

This study was carried out to suggest an experimental base in selecting the cold tolerance of plants. The cold tolerance of the plants were subject to laboratory low temperature treatments and cold processing time were evaluated using both electrolyte leakage and regrowth test. The Logistic model of nonlinear regression analysis was used to evaluate the lethal temperatures that were predicted with the range of $-16.1{\sim}-24.4^{\circ}C$. The order of low-temperature resistance was Sedum reflexum > S. spurium > Ophiopogon japonicus > S. album > S. takevimense > Dianthus chinensis. At the lowest temperature of $13.4^{\circ}C$ the electrolyte leakage value of the plants were lower than 50% demonstrating that they could be applied stably to the roof installed in Korea during the winter with the lowest temperature of $-13.5^{\circ}C$.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.175-175
• /
• 2017

To understand molecular mechanisms underlying adaptation of plant cells to saline stress and stress memory, we developed Arabidopsis callus suspension-cultured cells adapted to high salt. Adapted cells to high salt exhibited enhanced tolerance compared to control cells. Moreover, the salt tolerance of adapted cells was stably maintained even after the stress is relieved, indicating that the acquired salt tolerance of adapted cells was memorized. In order to characterize metabolic responses of plant cells during adaptation to high salt stress as well as stress memory, we compared metabolic profiles of salt-adapted and stress-memorized cells with control cells by using NMR spectroscopy. A principle component analysis showed clear metabolic discrimination among control, salt-adapted and stress-memorized cells. Compared with control cells, metabolites related to shikimate metabolism such as tyrosine, and flavonol glycosides, which are related to protective mechanism of plant against stresses were largely up-regulated in adapted cell lines. Moreover, coniferin, a precursor of lignin, was more abundant in salt-adapted cells than control cells. Cell morphology analysis using transmission electron microscopy indicated that cell wall thickness of salt-adapted cells was significantly induced compared to control cells. Consistently, salt adapted cells contained more lignin in their cell walls compared to control cells. The results provide new insight into mechanisms of plant adaptation to saline stress as well as stress memory in metabolic level.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.111-111
• /
• 2017

The development and productivity of maize (Zea mays L.) is frequently impacted by water scarcity, and consequently to increased drought tolerance in a priority target in maize breeding programs. To elucidate the molecular mechanisms of resistance to drought stress in maize, RNA-seq of the public database was used for transcriptome profiling of the seedling stage exposed to drought stress of three levels, such as moderate, severe drought stress and re-watering. In silico analysis of differentially expressed genes (DEGs), 176 up-regulated and 166 down-regulated DEGs was detected at moderated stress in tolerance type. These DEGs was increasing degradation of amino acid metabolism in biological pathways. Six modules based on a total of 4,771 DEGs responses to drought stress by the analysis of co-expression network between tolerance and susceptible type was constructed and showed to similar module types. These modules were discriminated yellow, greenyellow, turquoise, royalblue, brown4 and plum1 with 318, 2433, 375, 183, 1405 and 56 DEGs, respectively. This study was selected 30 DEGs to predicted drought stress response gene and was evaluated expression levels using drought stress treated sample and re-watering sample by quantitative Real-Time Polymerase Chain Reaction (qRT-PCR). 23 genes was shown increasing with drought stress and decreasing with re-watering. This study contribute to a better understanding of the molecular mechanisms of maize seedling stage responses to drought stress and could be useful for developing maize cultivar resistant to drought stress.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.11
• /
• pp.999-1011
• /
• 2015

In modern electronic warfare, RADAR is under constant threat of ECM(Electronic Counter Measures) signals from nearby jammers. The conventional linear frequency modulated(Linear-FM) waveform is easy to be intercepted to estimate its signal parameters due to its periodical phase transition. Recently, APCN(Advanced Pulse Compression Noise) waveform using random amplitude and phase transition was proposed for LPI(Low probability of Intercept). But random phase code signals such as APCN waveform tend to be sensitive to Doppler frequency shift and result in performance degradation during moving target detection. In this paper, random phase and code rate transition based radar waveform(RPCR) is proposed for Doppler tolerance improvement. Time frequency analysis is carried out through ambiguity analysis to validate the improved Doppler tolerance of RPCR waveform. As a means to measure the vulnerability of the proposed RPCR waveform against LPI, WHT(Wigner-Hough Transform) is adopted to analyze and estimate signal parameters for ECCM(Electronic Counter Counter Measures) application.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.42 no.3
• /
• pp.270-274
• /
• 1997

This experiment was conducted to evaluate the combining ability of japonica rices for improving the salinity tolerance at seedling stage. Nine varieties used in partial diallel analysis included three varieties of each tolerant, moderately tolerant and susceptible one. Twelve-day-old seedlings were grown in saline solution, initially at an EC of 6 dS /m for four days, followed by an EC of 12 dS /m for 20 days. The agronomic characters at seedling stage such as plant height, dry shoot weight and dry root weight were measured to analyze for combining ability of the parents. General combining ability(GCA) and specific combining ability(SCA) effects were highly significant for all tested parameters. However, mean squares for GCA were about five times larger than that for SCA suggesting the preponderance of additive gene action. Among tolerant varieties, Gaori and Namyang 7 were good combiner for improving the salinity tolerance at seedling stage in GCA as well as SCA.

• Journal of Aerospace System Engineering
• /
• v.13 no.5
• /
• pp.65-71
• /
• 2019

In this study, as a part of the aging aircraft performance improvement project for which no design information is provided, a new type of blade antenna is installed on the main part of the aging aircraft, and the method of proving the fatigue life of the main part of the aircraft is reviewed and summarized. There are various methods to prove fatigue life according to the manufacturer and aircraft design conditions. The fatigue life prediction and damage tolerance range of the relevant site were obtained through related regulations and industry examples. From these results, the fatigue life of newly installed antennas around the main parts of the aging aircraft was evaluated and the maintenance period and criteria were set according to the damage tolerance.

• Journal of the Optical Society of Korea
• /
• v.10 no.3
• /
• pp.118-123
• /
• 2006

We present an optical security method for binary data information by using 4-step phase-shifting digital holography and we analyze tolerance error for the decrypted data. 4-step phase-shifting digital holograms are acquired by moving the PZT mirror with equidistant phase steps of ${\pi}/2$ in the Mach-Zender type interferometer. The digital hologram in this method is a Fourier transform hologram and is quantized with 256 gray level. The decryption performance of the binary data information is analyzed. One of the most important errors is the quantization error in detecting the hologram intensity on CCD. The greater the number of quantization error pixels and the variation of gray level increase, the more the number of error bits increases for decryption. Computer experiments show the results for encryption and decryption with the proposed method and show the graph to analyze the tolerance of the quantization error in the system.

• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.1
• /
• pp.72-77
• /
• 2011

The checkpointing scheme is a well-known technique to cope with transient faults in digital systems. This paper proposes an adaptive checkpointing scheme for the reliability improvement of real-time control systems with concurrent fault detection capability. With concurrent fault detection capability the effect of transient faults are assumed to be detected with no latency. The proposed adaptive checkpointing scheme is based on the reliability analysis of an equidistant checkpointing scheme. Numerical data show the proposed adaptive scheme outperforms the equidistant scheme from a reliability point of view.