• Investigative Magnetic Resonance Imaging
• /
• v.23 no.3
• /
• pp.259-263
• /
• 2019

Although many imaging modalities can play some roles in the diagnosis of vertebral artery dissection (VAD), digital subtraction angiography (DSA) remains the gold standard method, with the highest detection rate and ability to assist in planning for endovascular treatment. However, this tool is often avoided in children because its invasive nature and it exposes them to radiation. High resolution magnetic resonance imaging (HR-MRI) have been suggested to be a reliable and non-invasive alternative, but it has never been discussed in children in whom vertebral artery dissection is a rare condition. In this report, we evaluate a case of a 2-year-old child who initially presented with cerebellar symptoms, and was early diagnosed with vertebral artery dissection using HR- MRI and was successfully treated.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.32 no.10
• /
• pp.112-117
• /
• 2004

This work is on numerical and experimental studies on the new type igniter using aerodynamic energy. The aerodynamic igniter consists of a nozzle and a resonance tube. The supersonic jet from a nozzle coming into the resonance tube generates pressure oscillation between the nozzle and the resonator. This oscillation changes the kinetic energy to thermal energy in the resonator under a certain condition. In this study, sonic and supersonic nozzles were tested in two different resonators, results has been compared. And geometrical optimum values of a supersonic nozzle has been suggested to reduce aerodynamic loss and friction in the expanded surface of the nozzle.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.3
• /
• pp.44-49
• /
• 2007

This paper proposes converter that new soft switching active snubber circuit is added, the resonance energy return to life rate doing maximum whole efficiency increase. Proposed converter adds auxiliary switch and resonance inductor, resonance capacitor, two diodes to existing converter, all switch elements play turn-on/turn-off under soft switching condition and minimized switching losses. Conduction loss department is that watch layer bringing back to life resonance energy by input perfectly. These result proved through simulation and an experiment.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2006.06a
• /
• pp.39-40
• /
• 2006

Diesel power plant(DPP) with the medium speed diesel engine is operated under the very severe condition in aspect of load and operating time as compared with the marine diesel generator set. So, minimized vibration level have to be insured for the more stable operation of engine and generator. The vibration of generator set mainly comes from the resonance between the rigid modes by resilient mount or distortion modes by structural stiffness and the excitation forces of engine. Then, avoidance of resonance with structural modification is generally well known. In this paper, the first order vibration in non-resonance range and local vibration modes were investigated by impact test, response/ODS(operational deflection shape) measurement and 3D finite element analysis for the additional reduction of vibration. The proposed countermeasures were actually applied and their final effects were verified through the in-situ measurement.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.324-324
• /
• 2008

Piezoelectric ceramics is an active element that makes stator to vibrate to generate rotational force in ultrasonic motors. In drive of ultrasonic motors, many factors that affect to the resonance characteristics of piezoelectric ceramics exist. For example, those factors are bonding condition with elastic body, the magnitude of electric field, the normal force for frictional drive and the emission of heat due to vibration and friction and so on. Therefore, it is important to research the inclination of property variation of piezoelectric ceramics in circumstance that has complex elements. In this paper, we focused and analyzed the resonance characteristics of ultrasonic motor due to the magnitude of the driving voltage and normal force.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.63 no.6
• /
• pp.776-779
• /
• 2014

In this paper, we analyzed the efficiency of magnetic resonance wireless power transmission (WPT) using superconductor coil according to the changing position of transmission and receiving coils. We implemented a WPT system using a magnetic resonance at a frequency of 63.1 kHz. Transmission and receiving coils using superconductor coil were wound on a spiral manner of diameter 100mm. For comparison, transmission and receiving coils using normal conductor coil were designed under the same condition. At a distance of 50mm, we measured efficiency when transmission-receiving coils were matched 25%, 50%, 75% and 100%. When a superconductor coil was applied to the transmission and receiving units, efficiency of WPT was very high. In addition, in the case of the superconducting transmission-receiving coils, when coils matched 100% the efficiency was 30% and matched 25% the efficiency was 8%.

• Korean Journal of Mathematics
• /
• v.25 no.4
• /
• pp.495-511
• /
• 2017

In this paper, we consider the system of three elliptic equations using two critical point theorem. We prove the existence of two solutions for suitable forcing terms, under a condition on the linear part which prevents resonance with eigenvalues of the operator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2010.05a
• /
• pp.614-615
• /
• 2010

• Korean Journal of Mathematics
• /
• v.16 no.4
• /
• pp.511-526
• /
• 2008

In this paper, we consider an elliptic system of three equations using the minimax theorem. We prove the existence of two solutions for suitable forcing terms, under a condition on the linear part which prevents resonance with eigenvalues of the operator.

• Korean Journal of Biological Psychiatry
• /
• v.15 no.2
• /
• pp.110-117
• /
• 2008

Objectives : Posttraumatic stress disorder(PTSD) has been primarily associated with emotional problems. Recently, however, the impact of PTSD on cognitive processes has interested a growing number of researchers. The current study is aimed at investigating the cognitive aspects of PTSD at both behavioral and neurological levels. Methods : We recruited individuals with PTSD who survived the Daegu subway explosion in 2003 as well as non-PTSD individuals as a control group. To evaluate the inhibitory processes and the neural mechanisms, we had these individuals perform the negative priming task simultaneously with functional MRI scanning. Results : Behaviorally, the negative priming effect was intact in the control group but was not evident in the PTSD group. In the imaging results, only the PTSD group showed the negative priming effect (i.e., increased activation of the negative priming condition as opposed to the neutral condition) in the dorsolateral prefrontal cortex, anterior cingulate cortex, and inferior temporal gyrus. The PTSD group also showed increased activity for the positive priming condition as opposed to the neutral condition in the claustrum. These results confirm and extend the previous findings that the integrity of the ACC is compromised in the trauma survivors due to disrupted white matter tract. Conclusions : The current results suggest that deteriorated performance of the PTSD group may be due to the functional problem as well as the structural abnormalities.