• 한국자기공명학회논문지
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• 제21권1호
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• pp.7-12
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• 2017

The nuclear magnetic resonance (NMR) and atomic magnetic resonance (AMR) plays a fundamental role in achieving a high accuracy of magnetic field measurements. Magnetic field unit (T) was realized based on the shielded proton gyromagnetic ratio (${\gamma}^{\prime}_P$), helium-4 gyromagnetic ratio (${\gamma}_{4He}$) and related techniques. The magnetic field standard system has been disseminated by the NMR magnetometer and electromagnet, a Helmholtz coil system, and AMR magnetometer in the nonmagnetic laboratory. A magnetic field standard below 1 mT has been developed by using Cs and Cs- $^4He$ AMR with automatic compensation of an external magnetic field noise. The standards serve for the calibration of magnetometers and support the test of sensors and materials in the range from $5{\mu}T$ to 2.0 T with (1 to 50) ${\mu}T/T$ uncertainty (k=2).

• 대한방사선기술학회지:방사선기술과학
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• 제22권1호
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• pp.35-42
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• 1999

This study was undertaken to take the correct vocal technique(especially about the resonance of oral cavity). The resonance of oral and pharyngeal cavity is the principle which can vocalize well without any abnormal signs in the throat. Therefore it is important for us to understand how to use the correct resonance of oral and pharyngeal cavity. Shimadzu X-ray remote control TV system and Shimadzu magnet $nex-{\alpha}$ (SMT-50CX/H) were used for checking the movements of T-M joint and diaphragmatic respiration. The results obtained were summerized as follows: 1. While opening T-M joint space like the vowel "A" [a], We should vocalize five fundamental vowel [a,e,i,o,u] with diaphragmatic respiration holded. 2. Diminuendo must be expressed by increasing a breath volume while descending a mandible gradually because we can not ascend maxilla. So we can make a delicate expression. 3. The resonance of oral cavity must be scattered by elevating the soft palatine lightly with relax of throat.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1613-1616
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• 2008

A Transcutaneous Energy Transmission System (TET) has been developed for the wireless energy transmission with two magnetically coupled coils. A resonance circuit is used to raise the induced voltage and current of the secondary coil. Its resonance frequency depends on the internal resistance of circuit and the transferred energy. Because the transferred energy usually changes in wide range, the output voltage is unstable and the energy transferring efficiency decrease. A push-pull class E amplifier is usedto generate high frequency AC voltage. To maintain proper resonance frequency, the voltage output of the amplifier was continuously monitored and adjusted to the optimized resonance frequency. Because of its high frequency (370 kHz), a phase lockedloop circuit and a comparator are used to monitor the output waveform. The results of experimentaldata show that the PLL circuit can increase the transmission efficiency and stabilize the output voltage of TET.

• 치과방사선
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• 제29권1호
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• pp.7-20
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• 1999

Magnetic resonance imaging with its superior soft tissue contrast resolution and absence of beam hardening artifacts, combined with its ability to perform multiplanar imaging, is now effective tool in diagnostic imagings. Magnetic resonance is primarily a phenomenon that involves atomic nuclei. It provides totally new clinical informations with no known hazards through the use of very weak interactions with endogenous stable magnetic atomic nuclei. This article briefly summarizes the basic mechanism of generation and detection of the signals and general sorts of tissue properties which can influence the signals and thereby give rise to tissue contrast. It also describes how the machine-operating parameters can be used to manipulate the tissue contrast observed in the image.

• 한국광학회지
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• 제2권2호
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• pp.59-66
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• 1991

표면 플라즈몬 공명이 일어나는 공명각과 최적 두께를 여러 금속 박막에 대해 어드미턴스 다이어그램을 이용하여 계산하였으며, 표면 플라즈몬 공명에서 측정한 반사율과 이론치를 곡선 맞춤하여 은박막과 알루미늄 박막의 광학 상수와 두께를 결정하였다. 한 파장에 대해 두 개의 해가 존재하므로 알곤 레이저의 두 파장에서 같은 두께를 갖는 해를 광학 상수의 유일 해로 선택하였으며, 금속 박막을 공기 중에 노출시킬 경우, 박막의 표면 변화에 의해 이동된 표면 플라즈몬 공명으로부터 변화된 금속 박막의 광학 상수를 결정하였다.

• 한국자기공명학회논문지
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• 제23권2호
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• pp.40-45
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• 2019

The phase transition temperatures and thermodynamic properties of $(NH_4)_2MnCl_4{\cdot}2H_2O$ grown by the slow evaporation method were studied using differential scanning calorimetry and thermogravimetric analysis. A structural phase transition occurred at temperature $T_{C1}$ (=264 K), whereas the changes at $T_{C2}$ (=460 K) and $T_{C3}$ (=475 K) seemed to be chemical changes caused by thermal decomposition. In addition, the chemical shift and the spin-lattice relaxation time $T_{1{\rho}}$ were investigated using $^1H$ magic-angle spinning nuclear magnetic resonance (MAS NMR), in order to understand the role of $NH_4{^+}$ and $H_2O$. The rise in $T_{1{\rho}}$ with temperature was related to variations in the symmetry of the surrounding $H_2O$ and $NH_4{^+}$.

• Nuclear Engineering and Technology
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• 제49권5호
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• pp.1006-1009
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• 2017

We discuss the problems of scattering in this framework, and show that the applied method is very useful in the investigation of the effect of the resonance in the observed scattering cross sections. In this study, not only the scattering cross sections but also the decomposition of the scattering cross sections was computed for the ${\alpha}-{\alpha}$ system. To obtain the decomposition of scattering cross sections into resonance and residual continuum terms, the complex scaled orthogonality condition model and the extended completeness relation are used. Applying the present method to the ${\alpha}-{\alpha}$ and ${\alpha}-n$ systems, we obtained good reproduction of the observed phase shifts and cross sections. The decomposition into resonance and continuum terms makes clear that resonance contributions are dominant but continuum terms and their interference are not negligible. To understand the behavior of observed phase shifts and the shape of the cross sections, both resonance and continuum terms are calculated.

• 한국항해항만학회지
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• 제35권9호
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• pp.755-763
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• 2011

Recently, extreme tsunami waves generated by submarine earthquake have caused tremendous damages to the coastal cities and ports. Strong seiche oscillations and runups are observed in specific sea areas around the world. Although no frequent impacts to the coast of Korean peninsula, there exist some important events in the east of Korea in the past. This study focuses on two historical events and recalculate with different fault and rupture mechanism for prediction considering the recent trend of submarine earthquake. The present study of the 1983 Akita tsunamis demonstrates the multi-scale resonance along continental coasts. Together with the Nankai tsunami for inland sea, we have confirmed the inland sea resonance surrounded by islands in defining the impact along the coast. Coherence and wavelet analyses for deducing a predominant period and time frequency are useful in reasoning the inundation. The resonance modes, which are largely independent of the tsunami source, allow identification of at-risk communities and infrastructure for mitigation of tsunami hazards. Furthermore, understanding of the resonance and the predicted runups for the site of power plant and industrial complex in the east coast of Korea would allow better preparation for the future disasters.

• Journal of electromagnetic engineering and science
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• 제4권3호
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• pp.113-118
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• 2004

As an application of ring filters, a new and simple method to determine an inherent-ring-resonance frequency is introduced. The ring filter consists of a ring and two short stubs. They are connected at 90$^{\circ}$ and 270$^{\circ}$ points of the ring and the ring filter may be seen in such way that two filters are connected in parallel. Therefore, if the two powers of the two filters are out-of-phase at the output, the power excited at the input can not be delivered. That can be done by making difference in length of the two short stubs, and when a certain condition is satisfied, a frequency exists where all the excited power is reflected. That is the very inherent-ring-resonance frequency. In the lossless case, the return loss with the condition reaches 0 dB at the inherent-ring-resonance frequency but does not with conductor, dielectric losses and so on. Therefore, the effective loss tangent at a frequency of interest may be obtained correctly. To verify the method, two ring filters have been fabricated in microstrip lines and the measured results show good agreement with the predicted ones.

• 한국소음진동공학회논문집
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• 제22권4호
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• pp.352-357
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• 2012

The ground resonance instability of a helicopter with bearingless main rotor hub were investigated. The ground resonance instability is caused by an interaction between the blade lag motion and hub inplane motion. This instability occurs when the helicopter is on the ground and is important for soft-inplane rotors where the rotating lag mode frequency is less than the rotor rotational speed. For the analysis, the bearingless rotor was composed of blades, flexbeam, torque tube, damper, shear restrainer, and pitch links. The fuselage was modeled as a mass-damper-spring system having natural frequencies in roll and pitch motions. The rotor-fuselage coupling equations are derived in non-rotating frame to consider the rotor and fuselage equations in the same frame. The ground resonance instabilities for three cases where are without lead-lag damper and fuselage damping, with lead-lag damper and without fuselage damping, and finally with lead-lag damper and fuselage damping. There is no ground resonance instability in the only rotor-fuselage configuration with lead-lag damper and fuselage damping.