• 한국가시화정보학회:학술대회논문집
• /
• 2004.04a
• /
• pp.29-36
• /
• 2004

A numerical study is carried out on the detonation wave propagation through a T-shaped flame tube, which represents a crucial part of the combustion wave ignition (CWI) system aimed for simultaneous ignition of multiple combustion chambers by delivering detonation waves. The formulation includes the Euler equations and an induction-parameter model. The reaction rate is treated based on a chemical kinetics database obtained from a detailed chemistry mechanism. A second-order implicit time integration and a third-order TVD algorithm are Implemented to solve the theoretical model numerically. A total of more than two-million grid points are used to provide direct insight into the dynamics of the detonation wave. Several important phenomena including detonation wave propagation, degeneration, and re-initiation are carefully examined. Information obtained can be effectively used to facilitate the design and optimization of the flame tubes of CWI systems.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.10 no.2
• /
• pp.62-69
• /
• 2006

In transversely isotropic composite laminates, the velocities, the particle directions and the amplitudes of reflected and transmitted waves were obtained using the equation of motion, the constitutive equation, and the displacement equation expressed by wave number and frequency. Eigenvalue problem involving a velocity was solved by Snell's law. Finally, the results were confirmed by 7300 Carbon fiber/5208 Epoxy materials. This approach could be applied to the detection of flaws in transversely isotropic composite laminates by the water immersion C-scan procedure.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.12
• /
• pp.22-27
• /
• 2015

Conoscopic holography, which consists of two linear polarizers and two wave plates, and an uniaxial crystal, is incoherent holographic technology for three-dimensional display. In the uniaxial crystal, the wave from object divides into extraordinary and ordinary waves and phase difference between two waves is caused by the different refractive index of two waves. Four intensity patterns, which are made by phase difference, are obtained using LCLV(liquid crystal light valve) and conoscopic holography system. By combining four intensity patterns, the complex hologram without bias and conjugate image. In this paper, we propose the optimized system, which consists of a wave plate and a linear polarizer, and uniaxial crystal. In the proposed system, it doesn't need LCLV. By adjusting the azimuth angle of a linear polarizer and a wave plate, we derive four intensity patterns in recording plane. We demonstrate theoretically that the complex hologram with bias and a conjugate image is obtained using the proposed system.

• ETRI Journal
• /
• v.26 no.1
• /
• pp.61-64
• /
• 2004

We have explored the fabrication of an InP/InGaAs single heterojunction bipolar transistor (HBT) and a wave guide p-i-n photodiode (PD) on two kinds of double stacked layers for the implementation of an optoelectronic millimeter-wave monolithic integrated circuit (OEMMIC). We applied a photosensitive polyimide for passivation and integration to overcome the large difference between the HBT and PD layers of around $3{\mu}m$. Our experiment showed that the RF characteristics of the HBT were dependent on the location of the PD layer, while the dc performances of the HBTs and PDs were independent of the type of stacked layer used. The $F_t$ and $F_{max}$ of the HBTs on the HBT/PD stacked layer were 10% lower than those of the HBTs on the PD/HBT stacked layer.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2001.05b
• /
• pp.1133-1138
• /
• 2001

The focus of this paper is on the numerical investigation of obliquely incident wane interactions with a system composed of full submerged and floating dual buoy/vertical-flexible-membrane breakwaters placed in parallel with spacing. The fully submerged systems allow surface and bottom clearances to enable wave transmission over and under the system. The problem is formulated based on the two-dimensional multi-domain hydro-elastic linear wave-body interaction theory. The hydrodynamic interaction of oblique incident waves with the combination of the rigid and flexible bodies was solved by the distribution of the simple sources (modified Bessel function of fille second kind) tat satisfy the Helmholz governing equation. Using this computer program, the performance of various dual systems varying buoy radiuses and drafts, membrane lengths, clearances. spacing, mooring-lines stiffness, mooring types, water depth, and wave characteristics is thoroughly examined. It is found that the fully submerged and floating dual buoy/membrane breakwaters call, if it is properly tuned to the coming waves, have good performances ill reflecting the obliquely incident waves over a tilde range of wave frequency and headings.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.29 no.2
• /
• pp.93-97
• /
• 2009

An advantage of a magnetostrictive strip transducer for a long-range guided wave inspection is that the wave patterns are relatively clear and simple when compared to a conventional piezoelectric ultrasonic transducer. Therefore, if we can characterize the evolution of defect signals, it could be a promising tool for a structural health monitoring of pipes for a long period of time as well as an identification of flaws. However, when evaluating a signal during a realistic field examination, it should be careful because of some spurious signals or false indications, such as signals due to a directionality, multiple reflections, mode conversion, geometrical reflections etc. Mode converted signals from a realistic piping mockup were acquired and analysed. We found mode conversions between a torsional guided wave T(0,1) mode and a flexural F(1,3) or longitudinal L(0,2) mode generated by a magnetostrictive strip transducer. Based on the experimental observations, an interpretation of the source of the mode conversion is discussed in a viewpoint of electromagnetic properties and structure of the strip transducer.

• Journal of The Korean Society of Integrative Medicine
• /
• v.4 no.1
• /
• pp.85-97
• /
• 2016

Purpose : The purpose of this study was to investigate the effects on the muscle thickness and contraction time using sound wave vibrator and swiss ball. Methods : This study was performed on 20 subjects. 20 subjects were divided into two groups; Lumbar stability exercise using sound wave vibrator exercise(n=10)(Group1), Lumbar stability exercise using Swiss ball exercise(n=10)(Group2). Both of the group performed the exercise 3 times a week for 5 weeks. The data was analyzed by the paired t-test to compare before and after difference of factors on each group and the Independent t-test to compare the between groups. Results : Both group were increased muscle contracture time on Straight Leg Rise(SLR) test (p<0.05). It means both group were increased lumbar stability. However, by comparing the between groups, there were no statistically significant difference about muscle thickness of multifidus and transverse abdominal.(p>0.05). Conclusion : As a result of this study, we suggest that the sound wave vibrator may be effective exercise tool for lumbar stability exercise like a swiss ball.

• Journal of Biomedical Engineering Research
• /
• v.39 no.1
• /
• pp.55-61
• /
• 2018

The purpose of this study was to investigate the effect of a pillow simulated with cranial sacral therapy (CST) on sleep induction using electroencephalography (EEG). This study included 12 voluntary participants divided into experimental group (CST group) and control group (Non-CST group) to observe EEG changes. The position of the electrode for EEG measurement consists of 8 channels electrodes (Fp1, Fp2, F3, F4, T3, T4, P3 and P4). In this study, we measured the fall asleep time, change of brain activity and sleep wave ratio using EEG wave (${\delta}$, ${\theta}$, ${\alpha}$, ${\beta}$ and ${\gamma}$). As a result, the mean fall asleep time of the experimental group was shorter than that of the control group significantly (p < 0.001). Also in comparison with the control group, both the delta (d) and theta (q) wave corresponding to the slow waves showed a larger increase and the alpha (a) wave showed a larger decrease significantly. The slow waves of experimental group showed a higher rate of significant increase than the control group (p < 0.001). Therefore this study showed that pillow based on CST had an effective in improving sleep induction and quality.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.10
• /
• pp.5097-5104
• /
• 2013

To derive implication for marketing strategy for Korean cosmetic products in China, an analysis was conducted on the difference in quality perception and purchase behavior between two groups of Chinese women classified by their awareness of Korean Wave. Analytical methods including k-means clustering method, independent samples t-test, factor analysis were applied on the survey results of Chinese women residing in Guangzhou city. The positive impact of Korean Wave on quality perception and brand image is much stronger for higher awareness group, compared against for lower awareness group, that leads to higher product satisfaction and willingness to recommend purchases. Thus, marketing strategies need to be adjusted based on the difference in customers awareness of Korean Wave. However, the low price is the primary inducement for purchases for both groups, increased efforts to enhance brand image and product quality as premium products is strongly required, together with the utilization of Koran Wave.

• Korean Journal of Acupuncture
• /
• v.28 no.4
• /
• pp.101-112
• /
• 2011

Objectives : This study was done to investigate the degree of the pulse wave parameter of post-mastectomy women and to identify the relationships between each of them. Methods : Data were obtained from public health center in Busan Metropolitan city. Participants were 82 post-mastectomy women aged 31-82. the data collection was from Oct, 1, 2010 to Oct, 31, 2010. the data were analyzed with descriptive statistics, one-way ANOVA, Duncan test. A p-value less than .05 was considered significant by 2-tailed test. All statistical analyses were performed with SPSS/Win(ver 12.0). Results : As for the difference in the pulse wave by the general characteristics. The pulse energy was showed highly in the order of Chon, Quan and Chuk of left and right pulse respectively. In the pulse energy of left Quan and right Chon, the case of both mastectomy was showed highly and in the pulse energy of left Chuk, the case of right mastectomy was showed highly. Left and right pulse energy of menopause female were significantly higher than normal range except left Chon and Chuk. In h1, h2, h4, h5, t1, t2, AP and Aw, the pulse energy of left Chon was showed the largest significantly. In As, the pulse energy of right Chon was showed the smallest and in Ad, right Chuk was showed the largest. In RAI, right and left Chuk was showed the highest respectively. Conclusions : From these result, we can see that there are relation between women's age, area of operation breast and menopause after mastectomy in pulse wave. The result of this study will become basic data necessary for the Oriental Medicine treatment to reduce or prevent women's functional difficulties, symptomatology after mastectomy.