• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.843-847
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• 2007

The unbalanced mass of a high precision rotor deteriorates mechanical performance of the rotor. The geometrical center of a rotor generally corresponds to the rotational axis of the rotor. However, this alignment carried out with a stationary rotor does not guarantee the dynamic rotor balance. There have been a number of schemes for the correction of the imbalance published for decades especially in the hard drive industry where the issues are directly affecting manufacturing costs and product performances. Realizing the significance of the problem, the present work tries to refine one of the methods that works by applying external impact during a rotor spins. A systematic way to apply the external impact to a rotating rotor has been introduced to minimize imbalance correction process time.

• International Journal of Industrial Entomology and Biomaterials
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• v.25 no.2
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• pp.205-208
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• 2012

Antheraea pernyi silkworm is a well known wild silkworm to produce a valuable silk fiber. A. pernyi silkworm was reared in Korean oak field and examined the cocoon characteristics, such as cocoon weight, cocoon shell weight, and percentage of cocoon shell weight. Degumming loss was also measured after alkali degumming process. A. pernyi silkworm spins tawny color cocoon in oval shape. Cocoon shell weight of A. pernyi silkworm, 0.78 g, was heavier than that of B. mori silkworm, 0.51 to 0.63 g. Cocoon shell percentage of A. pernyi silkworm, 32.8%, was higher than that of B. mori silkworm, 23.4 to 25.2%. Degumming loss percentage of A. pernyi silkworm, 17.1%, was lower than that of B. mori silkworm, 25.0%. SEM showed that the surface of the cocoon filament was coarse and oriented with longitudinal direction.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.05
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• pp.92-97
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• 1992

The pulsatile nature of blood flow makes artefacts in 2D Fourier transform image. Spatial presaturation is known to be effective in eliminating flow artefacts when the spin echo acquisition is employed. However. this method requires additional RF pulse and spoiling gradient for presaturation. In this paper a new flow saturation technique which does not require additional saturation-RF and gradient is proposed. The proposed technique is equivalent to the existing saturation technique but the elimination of the flow component is achieved by a pair of tailored $90^{\circ}-180^{\circ}$ RF pulses in tile spin echo sequence. By use of two tailored RF pulses with opposite phase polarity, a linear phase gradient is generated for those moving materials and consequently all the spins of moving materials become dephased thereby no signal is observable. Computer simulations and experimental results obtained using both a phantom and a human volunteer with a 2.0 T whole body system are also presented.

• Advances in nano research
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• v.2 no.1
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• pp.15-22
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• 2014

In recent years, spins of confined carriers in quantum dots are promising candidates for the logical units in quantum computers. In many concepts developed so far, the individual spin q-bits are being manipulated by magnetic fields, which is difficult to achieve. In the current research the recent developments of spin based quantum computing has been reviewed. Then, Single-hole spin in a molecular quantum dots with less energy and more speed has been electrically manipulated and the results have been compared with the magnetic manipulating of the spin.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.46.4-47
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• 2016

About 50% of stars reside in binary or multiple systems. However, the formation mechanism of the multiplicity is poorly understood. Theoretical studies suggest two main mechanisms for the multiplicity: turbulent fragmentation and disk fragmentation. We can testify which mechanism is more plausible by measuring the separation between companions or the alignment of stellar spins. Here we present our ALMA Cycle 2 observational results of a proto-binary system, IRAS 04191+1523, which consists of two Class I sources. We detected disks around both Class I sources, which are located in a common dense filamentary structure traced by $C^{18}O$ J=2-1. Two protostellar disks are separated by ~900 AU and their rotational axes are almost perpendicular, which strongly support that this binary system formed by the turbulent fragmentation.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.169-169
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• 2001

Purpose： To assess the clinical usefulness of Transfer Insensitive Labeling Technique (TILT) in t evaluation of ischemic cerebrovascular disease. Method： Arterial spin labeling (ASL) is a method of perfusion weighted imaging usin endogenous water as a tracer. To avoid MT-related artifacts, which is common in usual A technique, a transfer insensitive labeling technique (TILT) was used, which globall manipulate macromolecular spins in the same way by both labeling and reference preparatio while free water is labeled in one case and left unchanged in the other. Philips Interal 1.5 T system was used. 40cm FOV and 32 repeated measurements were done because of the wea perfusion signal. 5 slices of supratentorial brain were obtained in 5 patients ｛MCA infar (n=3), moyamoya disease (n=2)｝. We simultaneously obtained contrast enhanced T2＊-weighted perfusion MRI and correlate to TILT images.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.155-161
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• 2001

Anisotropic DWI - Mapping of the Proton Diffusion "tensor". In neural ordered tissue, it is thought that water diffusion is mainly influenced by the presence of myelin sheaths and intracellular structures. Perpendicular to the fiber tracts, the cholesterol-laden myelin lipid bilayers might restrict or hinder the spins from diffusing through the normally highly permeable cytomembrane. Diffusion along the fiber is more or less determined by subcellular structures, such as the endoplasmatic reticulum, mitochondria, neuro-filaments and macromolecules. In addition to that, the entire complex of axons and stabilizing tissue (i.e., glia cells, astrocytes) is also assumed to influence diffusion due to the tortuosity of proton translation, but the uniform distribution of such cells throughout the brain might render this notion less important as initially anticipated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.8
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• pp.720-725
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• 2007

The unbalanced mass of a high precision rotor deteriorates mechanical performance of the rotor. The geometrical center of a rotor generally corresponds to the rotational axis of the rotor. However, this alignment carried out with a stationary rotor does not guarantee the dynamic rotor balance. There have been a number of schemes for the correction of the unbalance published for decades especially in the hard drive industry where the issues are directly affecting manufacturing costs and product performances. Realizing the significance of the problem, the present work tries to refine one of the methods that works by applying external impact during a rotor spins. A systematic way to apply the external impact to a rotating rotor has been introduced to minimize unbalance correction process time.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.06a
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• pp.266-267
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• 2003

The most distinguishing character of diluted magnetic semiconductors (DMSs) is a strong interaction between sp-carriers and localized d-spins (sp-d exchange interaction). Recently many "room-temperature (RT) ferromagnetic DMS" have been reported. However, it should be noted that their sp-d exchange interactions have not been confirmed yet. The lack of a clear evidence of the sp-d exchange interaction causes the controversy on the origin of the observed ferromagnetism. For the detection of the sp-d exchange interaction, magneto-optical spectroscopy such as a magnetic circular dichroism (MCD) measurement is the most powerful tool. By using the MCD spectroscopy, we have shown the sp-d exchange interactions in Zn$_{l-x}$Cr$_{x}$Te. Recently, we have obtained the RT ferromagnetism in a Zn$_{l-x}$Cr$_{x}$Te (x = 0.20) film.0) film.

• Journal of Magnetics
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• v.20 no.4
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• pp.342-346
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• 2015

The nuclear magnetic resonance of the $^{23}Na$ nucleus in a $NaBrO_3$ single crystal was investigated at the temperature range of 200 K~410 K. The tendencies of temperature dependence of the nuclear quadrupole coupling for the two magnetically inequivalent Na(I) and Na(II) centers are found to be opposite to each other. The nuclear spin-lattice relaxation mechanism of $^{23}Na$ in the $NaBrO_3$ crystal is investigated, and the result revealed that the Raman process is dominant in the temperature range investigated. The relaxation process of the $^{23}Na$ nuclear spins was well described by a single exponential function in time. The $T_1$ values of the $^{23}Na$ nuclei in the $NaBrO_3$ single crystal decreased with increasing temperature. The calculated activation energy for the $^{23}Na$ is $0.032{\pm}0.002eV$.