• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.164-167
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• 1999

This study concerns with the effect of fiber weight fraction on the fracture toughness of long glass-fiber reinforced polypropylene composites. Fracture tests were conducted using compact tension (CT) specimens made of glass fiber polypropylene composites. Three fiber weight fractions of 20%, 30%, and 40% were used. Fracture toughness was determined from the compliance method. Results showed that compliance decreased with increasing fiber weight fraction while critical load increased with fiber weight fraction. Averaged fracture toughness increased 14% as fiber weight fraction increased from 20% to 40%.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.512-517
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• 2003

The repeated loading responses of four shear-critical reinforced concrete beams, with two different shear span-to-depth ratios, were studied. One series of beams was reinforced using pairs of bundled stirrups with $90^{\circ}C$ standard hooks, having free end extensions of $6d_b$. The companion beams contained shear reinforcement made with larger diameter headed bars anchored with 50mm diameter circular heads. A single headed bar had the same area as a pair of bundled stirrups and hence the two series were comparable. The test results indicate that beams containing headed bar stirrups have a superior performance to companion beams containing bundled standard stirrups, with improved ductility, larger energy adsorption and enhanced post-peak load carrying capability. Due to splitting of the concrete cover and local crushing, the hooks of the standard stirrups opened, resulting in loss of anchorage. In contrast, the headed bar stirrups did not lose their anchorage and hence were able to develop strain hardening and also served to delay buckling of the flexural compression steel. Excellent load-deflection predictions were obtained by reducing the tension stiffening to account for repeated load effects.

• Journal of the Korean Society of Safety
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• v.15 no.2
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• pp.13-21
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• 2000

Under the mixed mode loading, it has been known that the influence of non-singular terms in the stress fields is serious, because the critical distance, ${\gamma}_o$ - the distance of nonlinear elastic region near the crack tip has no negligible value. In this paper, it has been studied on the influence of non-singular terms, T-stress, and the case of T=0, ${\sigma}cos^2{\beta}$, ${\sigma}cos(2{\beta})$ and $0.05{\sigma}cos(2{\beta})$, under uniaxial tension and compression. It has been seen that the T-stress of ${\sigma}cos(2{\beta})$ has better than others as comparing to the experimental data.

• Journal of Microbiology and Biotechnology
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• v.15 no.1
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• pp.55-58
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• 2005

Sophorolipid was produced by Candida bombicola ATCC 22214 from soybean dark oil, a byproduct of soybean oil processing. With a fed-batch culture of C. bombicola for 7 days, 90 g/l of sophorolipid was obtained. The CMC (critical micelle concentration) and minimum surface tension of the sophorolipid in aqueous solution were found to be 150 mg/l and 48 mN/m, respectively. The dispersion capability of sophorolipid was higher than that of the chemical surfactants such as SDS and Brij30. The molar solubility ratio (MSR) of 4-methylnaphthalene was 0.2. Linoleic and oleic acids were the main constituents of the fatty acid composition of the sophorolipid. The sophorolipid showed antimicrobial activity against Propionibacterium acne and Bacillus subtilis.

• Korean Journal of Adult Nursing
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• v.26 no.1
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• pp.117-128
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• 2014

Purpose: The views, perceptions, and feelings of nurses themselves would be important to quality of nursing and professionalism, and turnover intentions. The purpose of this study was to identify nurses 'self-image to develop a customized program. Methods: The Q-methodology which is to create a typology was used. The 40 selected Q-statements from each of 35 participants were classified into a shape of normal distribution using a nine point scale. The collected data were analyzed using a PC-QUANL program. Results: Three types of nurses 'self-image were identified: 'proactive self-image', 'critical self-image', and 'adaptive self-image'. Two consensus items in three types were extracted: 'need to develop healing therapies to overcome the constant tension and exhaustion from work', and 'just think as a colleague than the senior-junior relationship. Conclusion: The results is the typology and this leads to further research.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.2
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• pp.294-301
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• 2003

It is of often important to accurately predict the flow-induced vibration or dynamic instability of a pipeline conveying internal high speed flow in advance, which requires a very accurate solution method. In this study, first the dynamic equations for the axial and transverse vibrations of a pipeline are reduced from a set of pipe-dynamic equations derived in the previous study and then the spectral element model is formulated. The accuracy of the spectral element method (SEM) is then verified by comparing its results with the results obtained by finite element method (FEM). It is shown that the present spectral element model provides very accurate solutions by using an extremely small number of degrees-of-freedom when compared with FEM. The dynamics of a sample pipeline is investigated with varying the axial tension and the speed of internal flow.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1672-1677
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• 2003

In this paper, the spectral element model is derived for the vibration and stability analyses of an axially moving viscoelastic beam subjected to axial tension. The viscoelastic material is represented by using a one-dimensional constitutive equation of hereditary integral type. The accuracy of the present spectral element model is first verified by comparing the eigenvalues obtained by the present spectral element model-based SEM with those obtained by the exact theory and the conventional FEM. The effects of viscoelasticity on the vibration and stability of an example moving viscoelastic beam are numerically investigated.

• The Korean Journal of Pain
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• v.9 no.1
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• pp.105-108
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• 1996

Localized or radiating pain in the arm and shoulder joint may result after faulty alignment causing compression or tension on nerves, blood vessels, or supporting soft tissues. The critical site of faulty alignment is the quadrangular space in the axilla bounded by the teres major, teres minor, long head of triceps, and humerus. The axillary nerve emerges through this space to supply the deltoid and teres minor. The activity of the trigger point on teres minor compressing the axillary nerve causes pain to develop through the area of sensory distribution of cutaneous branch of the axillary nerve. Relieving compression on the axillary nerve and suprascapular nerve is the key point to relieving the pain. Spasm of the supraspinatus and infraspinatus compressing the suprascapular nerve caused pain to develop in the shoulder joint and scapular area. We treated those patients experiencing such pain with local anesthetic infiltration or I-R laser stimulation on the identified trigger points.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2001.11a
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• pp.43-47
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• 2001

This paper presents a study of the uniform metal droplet generation using laser. The theoretical model, based on the variational principle instead of solving the Wavier-Stokes equation with moving boundaries, is developed. Our model is considered the Young-Laplace equation and force equilibrium conditions. Surface tension coefficient is determined under the statical condition with induced differential equation by using experimental result. In case of dynamic vibration, metal droplet shape and critical detaching volume are predicted by recalculating of proposed model. The simulation result revealed that the developed model could reasonably describe the molten metal droplet behavior on vibration with metal wire.

• Journal of ILASS-Korea
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• v.12 no.4
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• pp.198-203
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• 2007

In the present work, surface wetting effect on spread-splash regime and transition criterion of the water and ethanol droplets impacting an unheated dry wall has been experimentally investigated. The droplet was directed on a polished STS plate and a glass slide, and the impinging behavior was visualized and recorded using a CCD camera. Droplet diameter and velocity approaching the wall were measured as well. The critical Sommerfeld number representing the spread-splash boundary for the ethanol droplet impinging on the substrates turned out to be smaller compared to that for the water droplet impinging on the substrates with the surface roughness condition remained unchanged. The shift of the transition boundary is considered to be due to the effect of the surface wettability represented by static contact angle and surface tension of droplet.