• Journal of the Korean Magnetics Society
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• v.11 no.6
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• pp.239-244
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• 2001

Recently, RF inductor having researched by many workers, we fabricated and investigated properties of RF inductors. In order to improve the Q-factor (Quality), we try to apply the patterned Fe$_{78.81}$Ta$_{8.47}$N$_{12.71}$ soft magnetic thin film of 5000 which shows magnetic anisotropy of 30 Oe. Thus, patterned magnetic film was artificially increased magnetic anisotropy lead to increasing of ferro-magnetic resonance frequency up to GHz band. Coil as part of inductor was fabricated by lift off process. The dimension of RF inductor was designed 47un, rectangular shape, and measured properties. In the case of Ti/Ag air core type inductor shows Q of 9, inductance of 8.4 nH at 2 GHz. Magnetic film employed inductor shows inductance of 9 nH and FMR resonance frequency was 700 MHz.

• Bulletin of the Korean Chemical Society
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• v.26 no.5
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• pp.740-746
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• 2005

In this article, we report the tandem mass spectrometry investigations for the electron capture efficiencies of the protons belonging to the different locations (generations) in a poly(propylene imine) dendrimer with three layers of a repeat unit (named as the third generation dendrimer). The employed tandem mass spectrometry methods include SORI-CAD (sustained off-resonance irradiation collisional activation dissociation) and ECD(electron capture dissociation) mass spectrometry. We obtained SORI-CAD spectra for the dendrimer ions in the different charge states, ranging from 2+ to 4+. The analysis of fragmentation sites provides the information as to where the protons are distributed among various generations of the dendrimer. Based upon this, a new strategy to study the electron capture efficiencies of the protons is utilized to examine a new type of triplycharged ions by SORI-CAD, i.e., the 3+ ions generated from the charge reduction of the native 4+ ions by ECD: (M+4H)$^{4+}\;+\;e^-\;{\rightarrow}$ (M+4H)$^{3+\bullet}$ ${\rightarrow}\;({H^{\bullet}}_{ejected}$) + (M+3H)$^{3+}\;\rightarrow$ CAD. Interestingly, comparison of these four SORICAD spectra indicates that the proton distribution in the charge-reduced 3+ ions is very close to that in the native 4+ ions. It further suggests that in this synthetic polymer ($\sim$1.7 kDa) with an artificial architecture, the electron capture efficiencies of the protons are actually insensitive to where they are located in the molecule. This is somewhat contradictory to common expectations that the protons in the inner generations may not be well exposed to the incoming electron irradiation as much as the outer ones are, thus may be less efficient for electron capture. This finding may carry some implications for the case of medium sized peptide ions with similar masses, which are known to show no obvious site-specific fragmentations in ECD MS.

• Journal of Korean Neurosurgical Society
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• v.58 no.4
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• pp.316-320
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• 2015

Objective : The main concern during transfemoral carotid artery stenting (CAS) is preventing cerebral embolus dislodgement. We compared clinical outcomes and intraprocedural embolization rates of CAS using a distal filter protection device or proximal balloon occlusion device. Methods : From January 2011 to March 2015, a series of 58 patients with symptomatic or asymptomatic internal carotid artery stenosis ${\geq}70%$ were treated with CAS with embolic protection device in single center. All patients underwent post-CAS diffusion-weighted magnetic resonance imaging (DW-MRI) to detect new ischemic lesions. We compared clinical outcomes and postprocedural embolization rates. Results : CAS was performed in all 61 patients. Distal filter protection success rate was 96.6% (28/29), whose mean age was 70.9 years, and mean stenosis was 81%. Their preprocedural infarction rate was 39% (11/28). Subsequent DW-MRI revealed 96 new ischemic lesions in 71% (20/28) patients. In contrast, the proximal balloon occlusion device success rate was 93.8% (30/32), whose mean age was 68.8 years and mean stenosis was 86%. Preprocedure infarction rate was 47% (14/30). DW-MRI revealed 45 new ischemic lesions in 57% (17/30) patients. Compared with distal filter protection device, proximal balloon occlusion device resulted in fewer ischemic lesions per patient (p=0.028). In each group, type of stent during CAS had no significant effect on number of periprocedural embolisms. Only 2 neurologic events occurred in the successfully treated patients (one from each group). Conclusion : Transfemoral CAS with proximal balloon occlusion device achieves good results. Compared with distal filter protection, proximal balloon occlusion might be more effective in reducing cerebral embolism during CAS.

• Journal of the Korean Magnetic Resonance Society
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• v.19 no.2
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• pp.74-82
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• 2015

Ryanodine receptor (RyR) is one of the two major $Ca^{2+}$ channels in membranes of intracellular $Ca^{2+}$ stores and is found in sarcoplasmic reticulum (SR), endoplasmic reticulum (ER). RyR1 is also the major calmodulin-binding protein of sarcoplasmic reticulum membranes. Residues 4064-4210 in the RyR1 polypeptide chain has similar primary sequence with calmodulin (CaM) and was designated as CaM-like domain (CaMLD). When expressed as a recombinant peptide, CaMLD showed several CaM-like properties in previous studies. Still, previous studies of CaMLD were focused on protein-protein interactions rather than its own properties. Here, we studied the expression of CaMLD and its sub-domains corresponding to each lobe of CaM in Escherichia coli. CaMLD could be obtained only as inclusion body, and it was refolded using urea solubilization followed by dialysis. Using spectroscopic approaches, such as NMR, circular dichroism, and gel filtration experiment, we found that the refolded CaMLD exists as nonspecific aggregate, even though it has alpha helical secondary structure. In comparison, the first half of CaMLD (R4061-4141) could be obtained as natively soluble protein with thioredoxin fusion. After the removal of the fusion tag, it exhibited folded and helical properties as shown by NMR and circular dichroism experiments. Its oligomeric status was different from CaMLD, existing as dimeric form in solution. However, the second half of the protein could not be obtained as soluble protein regardless of fusion tag. Based on these results, we believe that CaMLD, although similar to CaM in sequence, has quite different physicochemical properties and that the second half of the protein renders it the aggregative properties.

• Journal of radiological science and technology
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• v.15 no.2
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• pp.37-47
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• 1992

Magnetic Resonance Imaging(MRI) is one of the most expensive and sophisticated diagnostic tool and has been hailed as the most exciting event in medical imaging "since the introduction of X-rays", but a major disadvantage, high cost, is coming into focus especially in our country. To determine the status of distribution of MR imagers in Korea and to serve as a basic material for an efficient utilization of this Imaging machine, a retrospective survey of nationwide and regional(3 hospitals in Pusan) installations was performed. The results were as follows : 1. As of April 30, 1991, a total of 33 MRI units(24 for superconducting, 6 for permanent and 3 for resistive units) were set up and operated. 91% of the units were distributed in big cities with no one installation in 7 provinces among 12 provinces in our country. 85% of the units were imported. 2. Although 42.4% of the units were operated in Seoul, Taejeon had the best condition for the distribution of this imaging machine per population, hospital, and bed in Korea. 3. In Pusan : a) 5 units were operated with all superconducting magnet and medium magnetic field in type of machine. b) 80.1 % of the examinations were central nervous system(CNS). c) MRI examination occupied 1.4% of all radiographic examinations and the patients referred from other hospitals were composed of 23.4%% of all patients. 4. The average days under operating of MRI unit a week in Puasn were higher(5.5) than that of Seoul(4.5), but the average number of examinations and hours a week and a day, respectively(33, 8.4), was less than that of Seoul(57, 12.9). 5. The patients with positive MRI findings in a hospital(B) in Pusan was 74.5% on an average.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.3
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• pp.578-585
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• 2009

In this paper, we present the design of an electromagnetic scanning mirror with torsional springs. The scanning mirror consisting of torsional springs and electromagnetic coils was designed for the applications of laser animation systems. We analyzed and optimized three types of torsional springs, namely, straight beam springs (SBS), classic serpentine springs (CSS), and rotated serpentine springs (RSS). The torsional springs were analyzed in terms of electrical resistance, fabrication error tolerance, and resonance mode separation of each type using analytical formula or numerical analysis. The RSS has advantages over the others as follows: 1) A low resistance of conductors, 2) wide resonance mode separation, 3) strong fabrication error tolerance, 4) a small footprint. The double-layer coils were chosen instead of single-layer coils with respect to electromagnetic forces. It resulted in lower power consumption. The geometry of the scanning mirror was optimized by calculations; RSS turn was 12 and the width of double-layer coil was $100{\mu}m$, respectively. When the static rotational angle is 5 degrees, the power consumption of the mirror plate was calculated to be 9.35 mW since the resistance of the coil part and a current is $122{\Omega}$ and 8.75 mA, respectively. The power consumption of full device including the mirror plate and torsional springs was calculated to be 9.63 mW.

• Journal of Korean Neurosurgical Society
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• v.52 no.1
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• pp.42-47
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• 2012

Objective : The aim of this prospective study was to demonstrate the influence of some factors on the prognosis of microvascular decompression in 37 patients with trigeminal neuralgia. Methods : The results of microvascular decompression (MVD) in 37 patients with trigeminal neuralgia were evaluated at 6 months after surgery and were compared with clinical and operative findings. Results : The sex of the patient, the patient's age at surgery, the side of the pain, and the duration of symptoms before surgery did not play any significant roles in prognosis. Also, the visual analogue scale (VAS) of the patient, the duration of each pain attack, and the frequency of pain over 24 hours did not play any significant roles in prognosis. In addition, intraoperative detection of the type of conflicting vessel, the degree of severity of conflict, and the location of the conflict around the circumference of the root did not play any roles in prognosis. The only factors affecting the prognosis in MVD surgery were intraoperative detection of the site of the conflict along the root and neuroradiological compression signs on preoperative magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA). Conclusion : These findings demonstrated that if neurovascular compression is seen on preoperative MRI/MRA and/or compression is found intraoperative at the root entry zone, then the patient will most likely benefit from MVD surgery.

• Journal of the Korean Magnetic Resonance Society
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• v.16 no.1
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• pp.34-45
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• 2012

Melanocortin-4 receptor (MC4R) subtype is associated with obese humans. Especially, in a patient with severe early-onset obesity, novel heterozygous mutation in the MC4R gene was detected, resulting in an exchange of aspartic acid to asparagine in $90^{th}$ amino acid residue located in the predicted second trans-membrane domain (TM2). Mutations in the melanocortin-4 receptor (MC4R) gene are the most frequent monogenic causes of severe obesity which have been described as heterozygous with loss of function. In order to compare structure difference between MC4R wild type (MC4R-TM2-wt) and mutant (MC4R-TM2-D90N), we designed both MC4R-TM2-wt and MC4R-TM2-D90N construct in pET 21b vector. In this study, we optimized high-yield purification procedure for recombinant TM2-D90N. Eluted recombinant protein was resolubilized under urea condition for thrombin cleavage reaction and we conducted the high-performance liquid chromatography (HPLC) with reverse phase column under 1% acetonitrile, 0.01% TFA buffer solution. The molecular size of purified target peptide was confirmed by Tricine-SDS page analysis. To characterize MC4R-TM2-D90N, we have performed $^{15}N$-isotope labeling of peptide using M9 media and purified labeled target peptide for hetero-nuclear NMR spectroscopy.

• Journal of Astronomy and Space Sciences
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• v.20 no.3
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• pp.205-216
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• 2003

The attitude motion of a spin-stabilized, upper-stage spacecraft is investigated based on a two-body model, consisting of a symmetric body, representing the spacecraft, and a spherical pendulum, representing the liquid slag pool entrapped in the aft section of the rocket motor. Exact time-varying nonlinear equations are derived and used to eliminate the drawbacks of conventional linear models. To study the stability of the spacecraft's attitude motion, both the spacecraft and pendulum are assumed to be in states of steady spin about the symmetry axis of the spacecraft and the coupled time-varying nonlinear equation of the pendulum is simplified. A quasi-stationary solution to that equation and approximate resonance conditions are determined in terms of the system parameters. The analysis shows that the pendulum is subject to a combination of parametric and external-type excitation by the main body and that energy from the excited pendulum is fed into the main body to develop the coning instability. In this paper, numerical examples are presented to explain the mechanism of the coning angle growth and how angular momenta and disturbance moments are generated.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.4
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• pp.245-253
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• 2020

In this study, natural frequencies are compared using several pile-soil interaction (PSI) models to evaluate the effects of each model on resonance safety checks for a monopile type of wind turbine structure. Base spring, distributed spring, and three-dimensional brick-shell models represented the PSIs in the finite element model. To analyze the effects of the PSI models on a natural frequency, after a stiffness matrix calculation and Winkler-based beam model for base spring and distributed spring models were presented, respectively; natural frequencies from these models were investigated for monopiles with different geometries and soil properties. These results were compared with those from the brick-shell model. The results show that differences in the first natural frequency of the monopiles from each model are small when the small diameter of monopile penetrates hard soil and rock, while the distributed spring model can over-estimate the natural frequency for large monopiles installed in weak soil. Thus, an appropriate PSI model for natural frequency analyses should be adopted by considering soil conditions and structure scale.