• Journal of the Korean Magnetic Resonance Society
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• 제7권1호
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• pp.37-45
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• 2003

Human CD99 is a ubiquitous 32-kDa transmembrane protein encoded by mic2 gene. Recently it has been reported that expression of a splice variant of CD99 transmembrane protein (Type I and Type II) increases invasive ability of human breast cancer cells. To understand structural basis for cellular functions of CD99 Type II, we have initiated studies on hCD99$\^$TMcytoI/ using circular dichroism (CD) and multi-dimensional NMR spectroscopy. CD spectrum of hCD99$\^$TMytoI/ in the presence of 200mM DPC and CHAPS displayed an existence ${\alpha}$-helical conformation, showing that it could form an ${\alpha}$-helix under membrane environments. In addition, we have found that the cytoplasmic domain of CD99 would form symmetric dimmer in the presence of transmembrane domain. Although it has been rarely figured out the correlation between structure and functional mechanism of hCD99$\^$TMcytoI/, the dimerization or oligomerization would play an important role in its biological function.

• Journal of Ocean Engineering and Technology
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• 제10권4호
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• pp.10-16
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• 1996

The vibration due to progressive ocean waves is analyzed for a typical footing-type offshore airport platform. The platform is modelled as a spring-supported Euler beam and buoyancy change due to wave is considered as excitation force, under the assumption that the wave propagates without distortion by the structure. The results show that the natural frequencies of this structure are distributed very closely and are little affected by boundary conditions and that the response charateristics due to ocean waves are quite different according to the wave frequency. In this study, the wave frequencies are divided into three regions; the resonance region at which the response is governed by the resonance between the natural mode at the wave frequency and the corresponding modal component of the wave excitation force, the bending governed region at which the response is governed by the bending stiffness, and the spring (buoyancy) governed region at which the response is governed by the spring constant ahd therefore is same as the incident wave form.

• Journal of radiological science and technology
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• 제23권2호
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• pp.21-26
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• 2000

The classification of herniated intervertebral cervical disc types are clinically important, as treatment methods would be slightly different according to the specific type of the herniated disc. 423 patients who suffered from herniated intervertebral cervical discs were tested with Magnetic Resonance Imaging (MRI), to distinguish the type of the herniated discs. The followings are the results ; 1) The age of the patients tested ranged from 16 to 75 years old and the mean age of the patients was 41.4 years of age. 2) There were twice as many male patients, with a ratio of 288 : 135 men to women. 3) 101 patients suffered from single herniated discs, while 322 patients suffered from multi-herniated discs. 4) Of single herniated disc injuries, 52 patients had protruded discs (52%), while 25 patients had extruded discs (25%). 21 Patients (21%) had herniated intervertebral discs between $C_4{\sim}C_5$, and 51 patients (50%), and had the same injury between $C_5$ and $C_6$. 5) Of multi-herniated disc injuries, 140 patients had protruded discs(44%). while 45 patients had extruded discs (14%). 54 patients had both protruded and extruded discs(17%). 36 patients(11%), herniated discs $C_3{\sim}C_6$ ; 69 patients (21%), herniated discs $C_3{\sim}C_7$ ; 47 patients(15%) herniated discs $C_4{\sim}C_6$ and 67 patients(20%) herniated discs $C_5{\sim}C_7$.

• Proceedings of the KIEE Conference
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1324-1326
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• 2000

This paper proposes a Current-Fed Push Pull type DC-DC converter using LCCC Resonant circuit and Zero Voltage Switching function to reduce turn on and off loss at the switching instants. This paper have the advantage which is able to operating safely in load short, because of DC reactor is connected with resonance reactor in order to supply a fixed current with low ripple from DC Power supply. The capacitor ($C_1$, $C_2$) connected in switch are common using as resonance capacitor and ZVS capacitor. The analysis of the proposed Current-Fed Push Pull type DC-DC converter is generally described by using normalized parameter, and we have evaluated characteristic values which is needed to design a circuit. We confirm a rightfulness theoretical analysis by comparing a theoretical values and experimental values obtained from experiment using MOSFET as switching devices.

• The Bulletin of The Korean Astronomical Society
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• 제37권2호
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• pp.73.1-73.1
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• 2012

We use hydrodynamic simulations to study the physical properties of gaseous structures in barred galaxies and their relationships with the bar strength. We vary the bar mass fbar relative to the spheroidal component as well as its aspect ratio. We derive expressions for the bar strength Qb and the radius where the maximum bar torque occurs. When applied to observations, these expressions suggest that bars in real galaxies are most likely to have fbar = 0.25-0.5. Dust lanes approximately follow one of x1-orbits and tend to be more straight under a stronger and more elongated bar. A nuclear ring of a conventional x2 type forms only when the bar is not so massive or elongated. The radius of an x2-type ring is generally smaller than the inner Lindblad resonance, decreases systematically with increasing Qb, evidencing that the ring position is not determined by the resonance but by the bar strength. Nuclear spirals exist only when the ring is of the x2-type and sufficiently large in size. Unlike the other features, nuclear spirals are transient in that they start out as being tightly-wound and weak, and then due to the nonlinear effect unwind and become stronger until turning into shocks, with an unwinding rate higher for larger Qb.

• Journal of Power Electronics
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• 제19권4호
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• pp.1034-1044
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• 2019

In medium-voltage and high-voltage high-power converters, the switching devices need to operate at a low switching frequency to reduce power loss and increase the power capacity. This increases the delay of the signal sampling and PWM. It also makes the cross-couplings of the d-q current components more severe. In addition, the LCL filter has three cross-coupling loops and is prone to resonance. In order to solve these problems, this paper establishes a complex vector model of an LCL type grid-connected converter. Based on this model, two multiple decoupling current control strategies with passive damping / notch damping are proposed for the LCL type grid-connected converter. The proposed strategies can effectively eliminate the cross-couplings of the converter, achieve independent control of the d-q current components, expand the stable region and suppress the resonance of the LCL filter. Simulation and experimental results verify the correctness of the theoretical analysis and the feasibility of the proposed strategies.

• Journal of Power Electronics
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• 제19권3호
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• pp.655-664
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• 2019

In order to analyze the nonlinear phenomena of the bifurcation and chaos caused by the switching of nonlinear switching devices in inductively coupled power transfer (ICPT) systems, a Jacobian matrix model, based on discrete mapping numerical modeling, is established to judge the system stability of the periodic closed orbit and to study the nonlinear behavior of Hopf bifurcation in a system under full resonance. The general flow of the parameter design, based on the stability principle for ICPT systems, is proposed to avoid the chaos and bifurcation phenomena caused by unreasonable parameter selection. Firstly, based on the state equation of SS-type compensation, a three-dimensional bifurcation diagram with the coupling coefficient as the bifurcation parameter is established with a numerical simulation to observe the nonlinear phenomena in the system. Then Filippov's method based on a Jacobian matrix model is adopted to deduce the boundary of stable operation and to judge the type of the bifurcation in the system. Then the general flow of the parameter design based on the stability principle for ICPT systems is proposed through the above analysis to realize stable operation under the conditions of weak coupling. Finally, an experimental platform is built to confirm the correctness of the numerical simulation and modeling.

• Journal of Cardiovascular Imaging
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• 제30권3호
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• pp.202-211
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• 2022

BACKGROUND: This study aims to investigate normal changes throughout aging of the heart in cardiac magnetic resonance (CMR) imaging in healthy volunteers. While type 2 diabetes mellitus is a frequent finding in the elderly population, also the influence of this circumstance in otherwise healthy persons is part of our study. METHODS: In this prospective single-center trial, 75 healthy subjects in distinct age groups and 10 otherwise healthy diabetics were enrolled. All subjects underwent functional, flow sensitive, native T2- and T1-mapping in a 1.5T CMR scanner. RESULTS: No differences in right and left ventricular ejection fractions were observed between aging healthy groups. Bi-ventricular volumes lowered significantly (p<0.001) between the age groups. There was also a significant decrease in myocardial T1 values, aortic distensibility, and left ventricular peak diastolic strain rates. There were no differences in T2 mapping and the other deformation parameters. Patients with type 2 diabetes mellitus had lower end-diastolic volume indexes; all the other measurements were comparable. CONCLUSIONS: Aging processes in the healthy heart involve a decrease in ventricular volumes, with ejection fractions remaining normal. Stiffening of the myocardium and aorta and a decrease in T1 values are potential indications of age-related remodeling. Type 2 diabetes mellitus seems to have no major influence on aging processes of the heart.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제30권1호
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• pp.29-38
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• 2018

In order to evaluate the performance of the floating wave power, which is an axisymmetric oscillating water column type, linearized free surface boundary condition considering the influence of PTO (power takeoff) was derived and a finite element numerical model was established. Numerical experiments were carried out by varying cylinder length, skirt length, and depth of water, which are design parameters that can change the resonance of water column in cylinder and heave resonance of the float, which is considered to affect the power generation efficiency. Finally, the basic data necessary for the optimum design of the power generation system were obtained. As a result, the efficiency of the power generation system is dominated by the heave motion resonance of the float rather than the water column resonance in the cylinder, and the resonance condition for the heave motion can be changed efficiently by attaching the skirt to the outside of the buoy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.674-677
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• 2002

In this paper, two kinds of windmill type motors which have a disk shape and a ring shape piezoelectric ceramics were studied. And characteristics of two models were compared with each others. A windmill type ultrasonic motor is composed of a stator, a rotor, and a ball bearing. The stator is made of a piezoelectric ceramics and two metals endcaps. When the piezoelectric ceramics vibrate, displacement of torsonal vibration appear at metal endcaps. The motor with 11.0[mm] diameter was studied by finite element analysis. The voltage of 100[V] was supplied at each model. Resonance frequency of 206.875[KHz] was obtained at the disk type, but ring type was 137.562[KHz]. The maximum torsonal displacement of $1.112[{\mu}m]$ was obtained at the disk type, but ring type was $1.698[{\mu}m]$.