• 대한기계학회논문집A
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• 제20권2호
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• pp.450-460
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• 1996

To investigate the effect of stress wave propagation for crack tip, impact responses of two-dimensional plates with oblique cracks are investigated by a numerical method. In the numerical analysis, the finite element method is used in space domain discretization and the Newmark constant acceleration algorithm is used in time integration. According to the numerical results from the impact response analysis. it is found that the stress fields are bisected at the crack surface and the parts of stress intensity are moved along the crack face. The crack tip stress fields are yaried rapidly. The magnitude of crack tip stress fields are converted to dynamic stress intensity factor. Dynamic sress intensity factor appears when the stress wave has reached at the crack tip and the aspect of change of dynamic stress intensity factor is shown to be the same as the part of the flow of stress intensity.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 추계학술대회 논문집
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• pp.303-308
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• 2003

In this paper, wave numerical modeling was experimented for the analysis of impact factors for the wave transmission as the incident wave and topographic conditions in the narrow channel sea. Recently, Although the results of many researcher for the wave modelling, numerical equations have limited to simulation of wave transformation effects. Despite of thispresent problems, the models was used to design the coastal structures in barrow channel sites. Finally, this paper estimated the wave model(mild slope eq. model) as the analysis of the wave energy transmission according to changing of impact factors(width of channel, bottom slope in channel, incident wave angle, wave period). As the results of numerical experiment, the major impact factors which influence to wave energy transmission were the width of channel and incident wave direction. But in the case that the width of channel is larger than 3L(L=Length of wave), the reduction of wave energy was small.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1995년도 정기학술강연회 발표논문 초록집
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• pp.120-121
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• 1995

In the design of mixed type breakwater, the most important factor to be considered is the wave pressure. In particular, the standing wave pressure has a significant effect on the vertical wall breakwater or mixed type breakwater. Many wave pressure formulas were developed and the Goda's formula［1］ was very frequently used among them by the coastal engineers due to its simplicity and accuracy. (omitted)

• 한국해안·해양공학회논문집
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• 제20권3호
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• pp.300-309
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• 2008

지금까지 연구된 피복석의 부분안전계수는 각 확률변수가 독립이라고 가정하여 계산하였다. 하지만 피복석의 안정공식 중 van der Meer 공식에서 파형경사와 파고는 독립이 아니며 상관성을 가지고 있다. 본 연구에서는 이들의 상관성을 고려한 부분안전계수를 산정하였고 이를 상관성을 고려하지 않은 다른 연구자들의 결과와 비교하였다. 파고와 파형경사의 상관성은 주기의 변동성과 밀접한 관계가 있다. 주기의 변동성이 작아짐에 따라 파고와 파형경사의 상관성은 커지며, 상관성 고려 여부에 따른 계산 결과의 차이가 커진다. 따라서 주기의 변동성이 작은 지역에서는 상관성을 충분히 검토하여 부분안전계수를 산정해야 할 것이다.

• 비파괴검사학회지
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• 제11권1호
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• pp.23-30
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• 1991

In this study the bonding quality evaluation of FRP honeycomb structure was performed by the ultrasonic C-Scan method and stress wave factor measurements. These NDT techniques could be well applied to the disbonding detection of FRP honeycomb structures. Especially, stress wave factor (SWF) measurement is expected to be a useful technique in field applications.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2562-2564
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• 1999

We have development the electronic ballast for metal halide discharge (MHD) lamp. The ballast consists of the boost pre-converter for power factor correction (PFC), a flyback a converter, half-bridge inverter and ignitor. To reject acoustic resonance phenomena, we have designed electronic ballast driving with the low frequency square wave. As results of this study, the ballast had not flicker phenomena and promoted corrected the factor (PF) highly

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
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• pp.191-199
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• 2000

The reflection-amplitude approximation is used to calculate the interlayer exchange coupling in (001) Co/Cu/Co multilayers. The dependence of the phase factor of the reflection amplitude on the energy and wave vector is included. The contribution of each period is calculated and the results are compared with those from the asymptotic behavior. It is shown that the energy and wave-vector dependence of the phase factor may affect the interlayer exchange coupling significantly.

• 복식
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• 제56권4호
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• pp.124-133
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• 2006

Human hair could be damaged by various physicochemical conditions and treatment. Permanent and decoloring treatment were the most serious factor on hair damage. The new permanent wave lotion containing Permeation enhancers such as Cremophor EL, Transcutol and propylene glycol based on cysteine permanent wave lotion were prepared. Efficiency of permanent wave and hair damage following pH of permanent wave lotion and addition of permeation enhancer were investigated. PH of solution, wave efficiency, loss of protein from hair, morphology of hair by SEM and solubility of alkaline solution were evaluated. The addition of Cremophor EL and Transcutol with ethanol increased permanent wave efficacy and decreased hair damage effectively. They diminished permanent wave lotion's pH and augmented permanent wave lotion's penetration compare to cysteine permanent wave lotion. new permanent wave lotion containing permeation enhancers such as Cremophor EL could be a good candidate for a new permanent wave lotion.

• 대한한의학회지
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• 제29권5호
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• pp.104-110
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• 2008

Objectives : The purpose of this study is to develop the method of selecting representative pulse wave. Methods : The pulse waves were acquired at the right and the left Guan point(關部) with 1420 people who were apparently healthy. The shape agreement of right and left pulse wave and the floating-sinking ratio were compared with three cases, which were the pulse height based method, the pulse area based method, and the pulse time based method. Results : In the point of the shape accordance, the pulse time based method was the best, and the pulse area based method was the worst. In the point of the floating-sinking ratio, the pulse height based method was the worst, and the pulse time based method was the best. Conclusions : So, the pulse time based method was recommended for selecting the representative pulse wave. This study compared the selection methods of representative pulse using the physiological characteristics of pulse wave. Further studies are required, because the representative pulse wave is the main factor of determining the shape and the floating-sinking characteristic of the pulse wave.

• International Journal of Aeronautical and Space Sciences
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• 제7권2호
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• pp.26-32
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• 2006

This paper targets a direct and quantitative prediction of characteristics of unstable waves in a combustion chamber, which employs the governing equations derived in terms of amplification factors of flow variables. A freshly formulated nonlinear acoustic equation is obtained and the analysis of unsteady waves in a rocket engine is attempted. In the present formalism, perturbation method decomposes the variables into time-averaged part that can be obtained easily and accurately and time-varying part which is assumed to be harmonic. Excluding the use of conventional spatially sinusoidal eigenfunctions, a direct numerical solution of wave equation replaces the initial spatial distribution of standing waves and forms the nonlinear space-averaged terms. Amplification factor is also calculated independently by the time rate of changes of fluctuating variables, and is no longer an explicit function for compulsory representation. Employing only the numerical computation, major assumptions inevitably inherent, and in erroneous manner, in up to date analytical methods could be avoided. With two definitions of amplification factor, 1-D stable wave and 3-D unstable wave are examined, and clearly demonstrated the potentiality of a suggested theoretical-numerical method of combustion instability.