• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.2 s.233
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• pp.303-310
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• 2005

The systems with probe and SIL(Solid Immersion Lens) mechanisms have been researched as the technology to perform NFR(Near Field Recording). Most of them use the flying head mechanism to accomplish high recording density and fast data transfer rate. In this paper, ABS shape of flying head was optimized with the object of securing the maximum compliance ability of OFH. We suggest low different optimization processes to predict the static flying characteristics for the OFH. Two different approximation methods, regression analysis and back propagation neural network were used. And we compared the result of directly connected(between CAE and optimizer) method and two approximated optimization results. Design Optimization Tool(DOT) and ${\mu}GA$ were used as the optimizers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.160-163
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• 2002

Silica waveguide for an integrated diffractive optical head system was designed and fabricated. The waveguide was designed to optimize the optical efficiency of red and/or blue laser source, and a lab-made RF magnetron sputter was adopted to deposit silica cladding and core layers on SiO$_2$/Si substrates. The cladding and core layers were formed using commercial targets, and the former was done with ＃7740 and the latter with BK7 and BAK4, respectively The surface roughness of the waveguide layers was measured to be 30.3${\AA}$ for BK7 and 17.8${\AA}$ for BAK4, and the difference of refractive indices between core and cladding layers was 0.9% and 2.5%, respectively. The waveguide fabricated with the core layer of BK7 showed better optical properties when the final diffractive optical probe heads were measured with red laser(650nm) source.

• Korean Journal of Head & Neck Oncology
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• v.16 no.1
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• pp.3-8
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• 2000

Background and Objectives: Adenoid cystic carcinoma of salivary glands is characterized by insidious growth over many years, local recurrences, and distant metastasis and classified to three distinct histologic subtypes: tubular, cribriform, and solid. The solid type is known to have the worst prognosis. However, histopathologic heterogeneity is observed in tumors from the same patient. We have attempted to elucidate the genotypic differences, characterized by polysomies of chromosome 17, in adenoid cystic carcinoma according to the phenotypic histopathologic heterogeneity. Materials and Methods: Fluorescence in situ hybridization was performed on formalin-fixed paraffin blocks from seven patients with head and neck adenoid cystic carcinoma, using the centromeric $\alpha$-satellite probe of chromosome 17 to detect nuclei exhibiting polysomy. The difference in polysomeric chromosome expression in cribriform, tubular, solid type and type I, II, III according to the Szanto classification was analyzed. Results: Polysomy of chromosome 17 was found in 15.28% of the cribriform type, in 15.68% of the tubular type, and in 18.87% of the solid type. The proportion of polysomy was statistically higher in the solid type than in the cribriform type(p<0.05), and the proportion of polysomy increased progressively from type 1 to type 3, but this trend was statistically insignificant(p>0.05). Conclusion: We suggest that there may be genetic variations in tumor from the same patient depending on the histopathologic heterogenetiy in adenoid cystic carcinomas.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.47-52
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• 2005

A lot of information storage devices have been introduced and developed for recently years. The trends of those devices are high capacity, compact size, low power consumption, reliability, and removability for data interchange with other device. As a satisfaction of these trends, near-field technique is in the spotlight as the next generation device. In order for a near-field recording to be successfully implemented in the storage device, a slider and suspension is introduced as actuating mechanism. The optical slider is designed considering near-filed optics. Suspension is not only supports slider performance, and tracking servo capacity but also meets the optical characteristics such as tilt aberration, and guarantee to satisfy shock performances for the mobility fir the actuator. In this study, the optical slider and the suspension for near-field probe array are designed and analyzed considering dynamic performance of head-gimbal assembly and shock simulation..

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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• pp.1-8
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• 2000

A new method of knock detection in SI engines, using a change of ion concentration in the combustion chamber, was developed. In order to measure in-cylinder ionization current, ionization probes were installed at spark plug and cylinder head of production engine. It was found that the electric current generated by ionized gas in core burned gas region of knocking cycle is between 2 and 10 times larger than that of normal cycle, because the burned gas temperature which is the dominant parameter of a change of ion concentration increases. However, a change of ionization current in boundary region of burned gas is relatively weak. Hence a change of ion concentration in core burned gas region can be used for knock detection.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.4
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• pp.600-610
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• 1995

When combustion gas is cooled down below the dew point of sulfuric acid vapor in the heat recovery systems, condensation occurs. Since the condensed sulfuric acid solution causes low-temperature corrosion in materials, it is important to measure the SOx dew point by electric measurement. In this study, two kinds of probes having electric gaps of 1mm or 2mm were used. and experiments were carried out by the parameters of sulfuric acid vapor and water vapor concentration. The changes of electric current caused by sulfuric acid condensed on the surface of probe according to the cooling rate and the probe head surface temperature were sudied. The opimum cooling rate was decreased with the increasing of water vaper concentration regardless of sulfuric acid concentration. The sensitivity of electric current is improved for the narrower gap(1mm) of ring electrodes, but it rarely affects the SOx dew point measuring of different probes according to the change of cooling rate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.422-430
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• 1996

The automated scanning laser Doppler vibrometer (LDV) has been designed, and built to measure in-plane displacements associated with waves propagating on vibrating structures. Use of optical fibers allows the compact design of a laser probe head which can be scanned over the vibrating structures. An algorithm for automated self-alignment of the laser probe is developed. The system is completely automated for scanning over the structures, focusing two laser beams at each data point until the detected vibration signal is stable, and for recording and transferring the data to a system computer. The automated system allows one to get extensive data of the vibration field over the structures. The system is tested by scanning a piezoelectric cylindrical shell and a plate excited by a continuous signal and by a pulse signal, respectively. Results show that the automated scanning LDV system can be a useful tool to measure the in-plane vibration field and to detect the elastic waves propagating on the vibrating structures.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.153-161
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• 1998

The knock in a spark ignition engine has been investigated to avoid the damage to the engine and unpleasant feeling caused by the pressure waves propagating across the combustion chamber. Knock intensity and knock onset angle were used as physical parameters to quantify the knock characteristics. The knock intensity is defined as a peak to peak value of the bank pass filtered combustion pressure signal and the knock onset angle is determined as the crank angle at which this signal exceeded the threshold level on each cycle. The cyclic variation of knock in four valve single cylinder engine was investigated with these two parameters. The location of autoignition was also examined by ion probes in the cylinder head gasket and squish region in the combustion chamber. For this measurement, a single cylinder engine was modified to accept the pressure transducer, 18 ion probes in the squish region and 8 ion probes in the specially designed PCB (Printed \ulcornerCircuit Board) cylinder head gasket.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.310-313
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• 2003

Complex permittivities of human head simulating liquids were measured by a sample holder of terminated slotted coaxial line with a movable probe at mobile communication frequencies. The validity of the liquid measurement system was checked by experiments with the reference liquids. Liquids of ingredients for human brain suggested in IEEE draft and those made by the authors were measured by this slotted line system.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.16 no.1
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• pp.15-18
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• 2005

Background and Objectives : To determine the changes of reflux symptoms and laryngoscopic findings of patients with laryngopharyngeal reflux (LPR) on the duration of proton pump inhibitor medication. Materials and Methods : From Feb 2003 to Nov 2004, 58 patients who were diagnosed with LPR by 24-hour double-probe pH monitoring were enrolled. All patients were treated with proton pump inhibitor and followed up for 8 weeks at least. The response of symptoms and laryngoscopic findings of patients were assessed with reflux symptom index (RSI) and reflux finding score (RFS) before treatment and 2, 4, 8, 12, 16, 20 weeks after treatment. Results : The symptoms of patients with LPR were improved significantly at 2, 4, 8 weeks of treatment. The laryngoscopic findings of patients with LPR were improved significantly at 4 and 12 weeks of treatment. There was no correlation between improvement of reflux symptoms and laryngoscopic findings. Conclusions : The laryngoscopic findings of LPR patients were improved more slowly than reflux symptoms. Based on our results, anti-reflux therapy might be continued at least for 3 months until the improvement of laryngoscopic findings.