• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.677-680
• /
• 2003

The effect of $B_2O_3$ addition on the sintering behavior and microwave dielectric properties of $(Zn_{0.8}Mg_{0.2})TiO_3$ ceramic system were investigated. Highly dense samples were obtained at the sintering temperatures below $900^{\circ}C$. Temperature coefficient of resonance frequency(${\tau}_f$) changes to a positive value with increasing the amount of $B_2O_3$ because of the increased amount of rutile phase. The $Q{\times}f_o$ values were determined by the microstructures and sintering shrinkages which are affected by the rutile or second phase. When 6.19 mol.% of $B_2O_3$ added and sintered at $900^{\circ}C$ for 5h, it exhibits ${\epsilon}_r$ =23.5, $Q{\times}f_o$= 67,500 GHz, and ${\tau}f=-1.42ppm/^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.05b
• /
• pp.47-50
• /
• 2000

The optical characteristics of merocyanine dyes have been investigated widely due to their possible application to the high efficiency photo-electric devices. The optical systems are mostly fabricated using vacuum evaporation, casting and Langmuir-Blodgett method and the arrangement and orientation of dye molecules is one of the most important factors in the study on the optical characteristics. In this study, we fabricated the molecular systems through the LB techniques and investigated the optical characteristics of merocyanine dye LB film using the oscillation characteristics of quartz crystal. It was quite interesting behavior that the resistance and frequency shift at the parallel resonance under the UV irradiation.

• BMB Reports
• /
• v.49 no.8
• /
• pp.431-436
• /
• 2016

Human papillomavirus (HPV) is the major cause of cervical cancer, a deadly threat to millions of females. The early oncogene product (E7) of the high-risk HPV16 is the primary agent associated with HPV-related cervical cancers. In order to understand how E7 contributes to the transforming activity, we investigated the structural features of the flexible N-terminal region (46 residues) of E7 by carrying out N-15 heteronuclear NMR experiments and replica exchange molecular dynamics simulations. Several NMR parameters as well as simulation ensemble structures indicate that this intrinsically disordered region of E7 contains two transient (10-20% populated) helical pre-structured motifs that overlap with important target binding moieties such as an E2F-mimic motif and a pRb-binding LXCXE segment. Presence of such target-binding motifs in HPV16 E7 provides a reasonable explanation for its promiscuous target-binding behavior associated with its transforming activity.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1995.10a
• /
• pp.197-200
• /
• 1995

Corrugation of railway track can be caused by the various dynamic behavior of travelling wheels and track. In this paper, the coupled vibrations of travelling wheel and railway track are analyzed as the cause of corrugations. To analyze the coupled vibrations, the track supported by the sleepers and the traveling wheel are identified to the elastically supported infinite beam and the spring-mass system which runs at constant speed. The Hertzian contact spring is considered betwen the infinite beam and spring-mass system. The dynamic responses of elastically supported infinite beam and spring-mass system are calculated. The cause and development of rail corrugation are discussed in the view point of contact force fluctuation affected by the elastic supports and the corrugated surface profile of the track. By the obtained results, the possibilities of resonance are checked between the excitation by the corrugated surface profile and the natural frequency of contact spring-moving mass system. It may be thought to a development of railway corrugation.

• Journal of Korean Neurosurgical Society
• /
• v.51 no.1
• /
• pp.47-50
• /
• 2012

We report here one case of rapid and aggressive course of cerebral metastatic angiosarcoma from the heart. A 36-year-old man presented with 10-days history of headache. Magnetic resonance imaging demonstrated subacute hemorrhage with a small region of enhancement in right parietal region and the pathological diagnosis was angiosarcoma. Transthoracic echocardiography demonstrated $3.2{\times}3$ cm sized mass on right atrial wall. Newly developed lesion was reoperated, three and four weeks later respectively, and whole brain radiotherapy of total 30 Gy was done. With the interval of two months, gamma knife surgery was done for new lesions two times, which were well controlled. Newly developed lesions rapidly happened even in the adjuvant treatment. He died 9 months after the diagnosis because of the aggravation of primary cancer. The cerebral metastatic angiosarcoma from the heart showed the rapid aggressive behavior and the closed follow-up could be needed for the adjuvant treatment.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.24 no.6
• /
• pp.589-593
• /
• 2015

The demand of high cycle fatigue behavior on plate material is increasing because of its various applications. However, the high-cycle fatigue life data of the plate material is very rare compared to the rod material. Thus, in this study, a plate specimen is designed for the ultrasonic fatigue test because it is time efficient as compared to the conventional fatigue test. To apply the ultrasonic fatigue test, the specimen design is required to resonate at 20 kHz. Therefore, the dynamic elastic modulus was determined by measuring the resonance frequency with a piezoelectric element and laser doppler vibrometer (LDV). As a result, the plate specimen is designed and demonstrated using the ultrasonic fatigue testing machine. The ultrasonic fatigue test results were compared with the hydraulic fatigue test results.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.12 no.5
• /
• pp.380-388
• /
• 2002

This paper describes the optimum design for low-pressure steam turbine rotor of 1,000 MW nuclear power plant by using a combined genetic algorithm, which uses both a genetic algorithm and a local concentrate search algorithm (e.g. simplex method). This algorithm is not only faster than the standard genetic algorithm but also supplies a more accurate solution. In addition, this algorithm can find the global and local optimum solutions. The objective is to minimize the resonance response (Q factor) and total weight of the shaft, and to separate the critical speeds as far from the operating speed as possible. These factors play very important roles in designing a rotor-bearing system under the dynamic behavior constraint. In the present work, the shaft diameter, the bearing length, and clearance are used as the design variables. The results show that the proposed algorithm can improve the Q factor and reduce the weight of the shaft and the 1st critical speed.

• Journal of Biosystems Engineering
• /
• v.27 no.4
• /
• pp.293-300
• /
• 2002

Surface crack detection is an important aspect in the quality control process of egg markets. The acoustic vibration of an egg could be used as a critical factor in evaluating the eggshell quality. The mode shape indicates the egg vibration behavior at different locations with respect to the input impulse and provides important information for the optimum sensor location to obtain the desired acoustic measurements. Theoretical analysis and experimental measurements were conducted to determine the acoustic vibration modes in eggs. The resonant fiequencies of the first and second resonance mode of intact eggs were found to be distributed between 2kHz and 7kHz range. The measured mode shapes of an egg were similar to theoretical shapes of homogeneous, elastic spheres. An elliptical deformation at the equator ring of the egg was observed. The frequency peak of this mode was dominantly present in the frequency spectrum of an intact egg impacted at its sharp position. The mode shapes related to the first resonant frequency of an egg shelved that the optimum location for the measuring sensor was the 180 degrees position. A optimum location for the egg support was found to be the 90 degrees position having the smallest vibration magnitude.

• Journal of Magnetics
• /
• v.3 no.4
• /
• pp.105-111
• /
• 1998

The low energy excitations of spin waves (SWR) in thin films can be used for determination of the surface anisotropy constant and the nonhomogeneities of magnetization in the close-to-surface layer. The dispersion relation in SWR is sensitive on the geometry of experiment. We report on temperature dependence of surface magnetic anisotropy energy constant in magnetic semiconductor thin films of$ CdCr_{2-2x}In_{2x}Se_4$ at spin glass state. Samples were deposited by rf sputtering technique on Corning glass substrate in controlled temperature conditions. Coexistence of the infinite ferromagnetic network (IFN) and finite spin slusters (FSC) in spin glass state (SG) is know phenomena. Some behavior typical for long range magnetic ordering is expected in samples at SG state. The spin wave resonance experiment (microwave spectrometer at X-band) with excited surface modes was applied to describe the energy state of surface spins. We determined the surface magnetic anisotropy energy constant versus temperature using the surface inhomogeneities model of magnetic thin films. It was found that two components contribute to the surface magnetic anisotropy energy. One originates from the exchange interaction term due to the lack of translation symmetry for surface spin as well as from the originates from the exchange interaction term due to the lack of translation symmetry for surface spin as well as from the stray field of the surface roughness. The second one comes from the demagnetizing field of close-to surface layer with grad M. Both term linearly decrease when temperature is increased from 5 to 123 K, but dominant contribution is from the first component.

• Journal of Power Electronics
• /
• v.16 no.6
• /
• pp.2202-2211
• /
• 2016

In certain applications, such as IPT-based EV charger (IPTEC), any variation in alignment and distance between pickup and charger primary leads to a change in leakage and magnetic impedance magnitudes. The power transmission capacity is not always at the maximum level because of these variations. This study proposes a new low-cost tracking method that achieves the Maximum Inductive Power Transmission Capacity (MIPTC). Furthermore, in the proposed method, the exchange of information between load and source is not required. For an application such as IPTEC, the load detected by the IPTEC varies continuously with time because of the change in state of the charge. This load variation causes a significant variation in IPT resonant circuit voltage gain. However, the optimized charging output voltage should be kept constant. From the analysis of the behavior of the IPT circuit at different working frequencies and load conditions, a MIPTC operation point that is independent of load condition can be identified. Finally, the experimental results of a developed prototype IPT circuit test show the performance of the proposed method.