• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.7
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• pp.561-568
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• 2013

After we designed Bearingless rotor hub system for 7,000lb class helicopter, flexbeam fatigue analysis was conducted for validation of requirement life time 8,000 hours. sectional structural analysis method applying elastic beam model was used. Fatigue analysis for two sections of flexbeam which were expected to weak to fatigue damage from result of static analysis was conducted. Extension, bending and torsion stiffness of flexbeam section shape was calculated using VABS for structure analysis. S-N curve of two composite material which composed flexbeam was generated using wohler equation. Load analysis of bearingless rotor system was conducted using CAMRAD II and load analysis result was applied HELIX/FELIX standard load spectrum to generate bearingless rotor system load spectrum which was used flexbeam fatigue safe life analysis.

• Journal of Fashion Business
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• v.7 no.2
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• pp.55-68
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• 2003

The purpose of this research is to expand the realm of a button for a decorative purpose through embossing the effect and gravity of a button in fashion by designing the new ceramic buttons which are mainly used for decorative function in costume. In order to acquire a motif for the design, I analyzed several works of Gustav Klimt. As the result, those feature can be classified into the use of decorative lines, mosaic forms, and harmony of golden yellow and black, and it can be applied to buttons and clothes design. The sort of clay used in manufacturing the ceramic buttons was white clay to have high density and to diffuse light well, and press shaping techniques using plaster mold were employed. The baking was performed in an electronic kiln at $800^{\circ}C$ for the first time and at $1250^{\circ}C$ for the second time. Based on wearable designs in 2002/2003 F/W Trend of Interfashion Planning, I made three pieces of dress which could express the button's capability of decoration with effect. This is expressing a simplified form which shows up in details of and yellow and red pink were used to harmonize with golden yellow clothes. As an application of shapes of foliage in I transformed its size and form to be consistent with a jacket and a tube top. To accord with golden beige costume, I made a curve, showing up in Klimt's paintings, with golden color on a circle shape which was also a main motif in his paintings.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.4
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• pp.318-327
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• 2012

The operating sound radiated from a laser printer includes tonal noise components caused by the rotating mechanical parts such as gear, shaft, motor, fan, etc. The negative effects of the tonal noise components need to be considered in the process of developing a sound quality index for the quantitative evaluation of the emotional satisfaction in terms of psycho-acoustics. However, in a previous paper, it was confirmed that the Aures tonality did not have enough correlation with the results of jury evaluation. The sound quality index based on loudness, articulation index, fluctuation strength has a little problem in considering the effects of rotating mechanical parts on the sound quality. In this paper, to solve the tonality evaluation problem, the calculation algorithm of Aures tonality was investigated in detail to find the cause of decreasing the correlation. The new tonality evaluation model was proposed by modifying and optimizing the masking effect, loudness ratio, and shape of weighting curve based on the basic algorithm of Aures tonality, and applied to two kinds of operating sound groups in order to verify the usefulness of proposed model. As a result, it is confirmed that the proposed tonality evaluation model has enough correlation and usefulness for expressing the tonalness in the operating sounds of laser printers. In the following paper, this results will be used to model the sound quality index as the input data by using the classification algorithm.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4A
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• pp.279-286
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• 2011

FRP (Fiber Reinforced Polymer) tendons can be used as an alternative to solve the corrosion problem of steel tendons. Material properties of FRP tendons-bond strength, transfer length, development length-must be determined in order to apply to concrete structures. First of all, in case of application for pretension concrete members with CFRP tendons, transfer length is an important characteristic. The bond of the material characteristics should be demanded clearly to apply to PSC structures prestressed with FRP tendons. This paper investigated on the bond characteristics of FRP reinforcements with various surface-type. To determine the bond characteristics of FRP materials used in place of steel reinforcement or prestressing tendon in concrete, pull-out testing suggested by CAN/CSA S806-02 was performed. A total of 40 specimens were made of concrete cube with steel strands, deformed steel bar and 6 different surface shape FRP materials like carbon or E-glass. Results of the bonding tests presented that each specimen showed various behaviors as the bond stress-slip curve and compared with the bond characteristic of CFRP tendon developed in Korea.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.4
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• pp.437-445
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• 2015

A design method for a perforated panel is suggested to reduce the level of incident noise without obstructing the flow of incoming fluid. The key idea was to insert an array of 1/4 wavelength tubes around the holes of the perforate panel. First, various case studies were performed for a unit model with only one hole. In order to avoid any increase in the panel thickness, the unit model was vertically divided into three layers, and only the middle layer was used as the design domain. The number and array of 1/4 wavelength tubes connected to the hole were optimized to obtain the widest effective frequency range in the transmission loss curve as possible. Then, the optimally designed unit model was converted to a periodic array in the perforated panel to achieve the design goals. Even if the target frequency and the target transmission loss were set to 1000 Hz and 10 dB, respectively, the suggested design method for the a perforated panel could achieve noise reduction for various target values.

• Journal of Preventive Medicine and Public Health
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• v.50 no.4
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• pp.278-281
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• 2017

Since 2006, type 1 diabetes in Finland has plateaued and then decreased after the authorities' decision to fortify dietary milk products with cholecalciferol. The role of vitamin D in innate and adaptive immunity is critical. A statistical error in the estimation of the recommended dietary allowance (RDA) for vitamin D was recently discovered; in a correct analysis of the data used by the Institute of Medicine, it was found that 8895 IU/d was needed for 97.5% of individuals to achieve values ${\geq}50nmol/L$. Another study confirmed that 6201 IU/d was needed to achieve 75 nmol/L and 9122 IU/d was needed to reach 100 nmol/L. The largest meta-analysis ever conducted of studies published between 1966 and 2013 showed that 25-hydroxyvitamin D levels <75 nmol/L may be too low for safety and associated with higher all-cause mortality, demolishing the previously presumed U-shape curve of mortality associated with vitamin D levels. Since all-disease mortality is reduced to 1.0 with serum vitamin D levels ${\geq}100nmol/L$, we call public health authorities to consider designating as the RDA at least three-fourths of the levels proposed by the Endocrine Society Expert Committee as safe upper tolerable daily intake doses. This could lead to a recommendation of 1000 IU for children <1 year on enriched formula and 1500 IU for breastfed children older than 6 months, 3000 IU for children >1 year of age, and around 8000 IU for young adults and thereafter. Actions are urgently needed to protect the global population from vitamin D deficiency.

• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.4
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• pp.71-80
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• 1990

Model tests for the ultimate pullout resistance of anchorages and investigation of failure behaviors in cohesionless soil have been conducted. The factors affecting the anchorage are mostly the geometry of the system, and soil properties of sands. The main conclusions of the experimental work were as follows. 1. The load - displacement relationship can be a form of parabolic curve for all plates. 2. The change in ultimate pullout resistance of anchor is mostly affected by embedment ratio and size of anchor, and influenced to a lesser degree by its shape. 3. Critical embedment ratio which is defined as the failure mode changes from shallow to deep mode is increased with increasing height of anchor. 4. For a constant anchor height, as the width of anchor increases the ultimate pullout resistance also increases. However, considering the efficiency of anchor for unit area, width of anchor does not appear to have any sigrnificant contribution on increasing anchor city. 5. Anchor capacity has a linear relation to sand density for any given section and the rate of change increases as the section increases. Critical depth determining the failure patterns of anchor is decreased with a decrease of sand density. 6. With increasing inclination angle, size of anchor, and decreasing embedment ratio, the ultimate pullout resistance of anchor under inclined loading is significantly decreased. 7. The ultimate pullout resistance of double anchor, a method of improving single of anchor capacity, is influenced by the center - to - center spacing adjacent anchors. It is also found that tandem and parallel anchor rigging arrangements decrease the anchor system capacity to less than twice the single anchor capacity due to anchor interference.

• Journal of Powder Materials
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• v.20 no.4
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• pp.280-284
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• 2013

Stress-strain curves are fundamental properties to study characteristics of materials. Flow stress curves of the powder materials are obtained by indirect testing methods, such as tensile test with the bulk materials and powder compaction test, because it is hard to measure the stress-strain curves of the powder materials using conventional uniaxial tensile test due to the limitation of the size and shape of the specimen. Instrumented nanoindentation can measure mechanical properties of very small region from several nanometers to several micrometers, so nanoindentation technique is suitable to obtain the stress-strain curve of the powder materials. In this study, a novel technique to obtain the stress-strain curves using the combination of instrumented nanoindentation and finite element method was introduced and the flow stress curves of Fe powder were measured. Then obtained stress-strain curves were verified by the comparison of the experimental results and the FEA results for powder compaction test.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.4
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• pp.243-250
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• 2011

Noise levels of the three subway lines of Busan city have been investigated. Averaged cabin noise of the train has been measured during the train trip for each station. It has been measured with separation of day time (9:00~18:00) and night time (18:00~22:00) measurements but there was no big difference on the measured data. Repeating for the measured data has been confirmed with twice measurements in May and June 2010. Several noise effects to the subway noise levels of Busan are explained. Those are screen door effect, rail road surface condition, subway train type and curvature of railway. Among three subway lines of Busan city, the line 2 is relatively noisy and its reasons are studied. It has been shown that the screen door effect is 10 dB(A) and S shape of sharp curve contributes in high noise level.

• Journal of Biomedical Engineering Research
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• v.33 no.4
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• pp.169-176
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• 2012

Tumor cell morphology is closely related to its migratory behaviors. An active tumor cell has a highly irregular shape, whereas a spherical cell is inactive. Thus, quantitative analysis of cell features is crucial to determine tumor malignancy or to test the efficacy of anticancer treatment. We use 3D time-lapse phase-contrast microscopy to analyze single cell morphology because it enables to observe long-term activity of living cells without photobleaching and phototoxicity, which is common in other fluorescence-labeled microscopy. Despite this advantage, there are image-level drawbacks to phase-contrast microscopy, such as local light effect and contrast interference ring. Therefore, we first corrected for non-uniform illumination artifacts and then we use intensity distribution information to detect cell boundary. In phase contrast microscopy image, cell is normally appeared as dark region surrounded by bright halo ring. Due to halo artifact is minimal around the cell body and has non-symmetric diffusion pattern, we calculate cross sectional plane which intersects center of each cell and orthogonal to first principal axis. Then, we extract dark cell region by analyzing intensity profile curve considering local bright peak as halo area. Finally, we calculated the Fourier descriptor that morphological characteristics of cell to classify tumor cells into active and inactive groups. We validated classification accuracy by comparing our findings with manually obtained results.