• Progress in Superconductivity
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• v.10 no.2
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• pp.139-143
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• 2009

We have fabricated a low-noise 61-channel axial-type first-order gradiometer system for measuring fetal magnetocardiography(MCG) signals. Superconducting quantum interference device(SQUID) sensor was based on double relaxation oscillation SQUID(DROS) for detecting biomagnetic signal, such as MCG, magnetoencphalogram(MEG) and fetal-MCG. The SQUID sensor detected axial component of fetal MCG signal. The pickup coil of SQUID sensor was wound with 120 ${\mu}m$ NbTi wire on bobbin(20 mm diameter) and was a first-order gradiometer to reject the environment noise. The sensors have low white noise of 3 $fT/Hz^{1/2}$ at 100 Hz on average. The fetal MCG was measured from $24{\sim}36$ weeks fetus in a magnetically shielded room(MSR) with shielding factor of 35 dB at 0.1 Hz and 80 dB at 100 Hz(comparatively mild shielding). The MCG signal contained maternal and fetal MCG. Fetal MCG could be distinguished relatively easily from maternal MCG by using independent component analysis(ICA) filter. In addition, we could observe T peak as well as QRS wave, respectively. It will be useful in detecting fetal cardiac diseases.

• Polymer(Korea)
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• v.33 no.5
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• pp.420-428
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• 2009

In this study, the composites containing carbon black (CB) or carbon fibers were prepared, and the microwave absorbing properties and the absorption mechanism of them were investigated and discussed in the frequency range of 2-18 GHz, respectively. The optimum mass fraction of CB has been found as 6%, and the carbon fibers were discovered to absorb radar wave either under parallel or vertical polarization, the suitable gap distance between each bundle of which was 5 mm. According to the results of the single constitute absorber samples, the structured composites with the two kinds of absorbers combination were fabricated and studied at 2-18 GHz. The top layer absorbers affect the absorption performance a lot; the maximum reflection loss of composites with CB as top layer absorbers was -31.8 dB with the frequency range of 2.4 GHz below -10 dB, and the other type with CFs as the top layer absorbers obtained the reflection loss peak value of -31.4 dB with 2 GHz below-10 dB.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.561-569
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• 2002

Laser has been called a "Quantum Machine" because of its mechanism of generation since the development on July 7,1960.by T.H.Maiman. We can now use this machine as a tool for manufacturing in industries. At present, 45kW CO2 laser, 10kW Nd:YAG laser, 6kW LD pumped YAG laser and 4kW direct diode laser facilities are available for welding a heavy steel plate of 40mm in thickness and for cutting metals at high speed of 140m/min. Laser Materials Processing is no longer a scientific curiosity but a modern tool in industries. Lasers in manufacturing sector are currently used in welding, cutting, drilling, cladding, marking, cleaning, micro-machining and forming. Recently, high power laser diode, 10kW LD pumped YAG laser, 700W fiber laser and excimer laser have been developed in the industrialized countries. As a result of large numbers of research and developments, the modem laser materials processing has been realized and used in all kinds of industries now. In the present paper, metallurgical studies on laser materials processing such as porosity formation, hot cracking and the joint performances of steels and aluminum alloys and dissimilar joint are discussed after the introduction of laser facilities and laser applications in industries such as automotive industry, electronics industry, and steel making industry. The wave towards the use of laser materials processing and its penetration into many industries has started in many countries now. Especially, development of high power/quality diode laser will be accelerate the introduction of this magnificent tool, because of the high efficiency of about 50%, long life time and compact.

• Journal of Veterinary Clinics
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• v.31 no.4
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• pp.325-328
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• 2014

A 8-month-old female Maltese dog was presented with a history of heart murmur. In physical examination, grade 4/6 systolic murmur heard at the left heart base. Electrocardiography showed sinus arrhythmia, right axis deviation, deep S wave and splintered QRS complex. Thoracic radiography revealed enlarged right side heart and bulging of the main pulmonary artery. Echocardiography showed mild hypertrophy of right ventricle, a supravalvular stenosis, marked post-stenotic dilation of the main pulmonary artery and a moderately increased pulmonary arterial velocity through the stenotic area (4.4 m/s, pressure gradient of 78.7 mmHg). The dog was diagnosed with supravalvular pulmonic stenosis based on the diagnostic imaging findings. Medical management using ${\beta}1$-blocker and ACE inhibitor was started in this dog and this is first case report described diagnostic characteristic features of supravalvular pulmonic stenosis in korea.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.104-113
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• 2013

A high-throughput Quasi-Cyclic Low-Density Parity-Check (QC-LDPC) decoder architecture is proposed for 60GHz multi-gigabit wireless personal area network (WPAN) applications. Two novel techniques which can apply to our selected QC-LDPC code are proposed, including a four block-parallel layered decoding technique and fixed wire network. Two-stage pipelining and four block-parallel layered decoding techniques are used to improve the clock speed and decoding throughput. Also, the fixed wire network is proposed to simplify the switch network. A 672-bit, rate-1/2 QC-LDPC decoder architecture has been designed and implemented using 90-nm CMOS standard cell technology. Synthesis results show that the proposed QC-LDPC decoder requires a 794K gate and can operate at 290 MHz to achieve a data throughput of 3.9 Gbps with a maximum of 12 iterations, which meet the requirement of 60 GHz WPAN applications.

• Journal of Periodontal and Implant Science
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• v.33 no.2
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• pp.139-147
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• 2003

The roots of teeth exposed by gingival recession, may be successfully covered by various type of gingival grafting procedures. Vascularization of the recipient site is an essential determinant of the grafts' survival during the first healing stages. It has been suggested that a procedure by which they stimulate the periosteum presurgically will induce the proliferation of neo-endothelium in the site to be operated. The purpose of this study is to evaluate the variations in the gingival blood flow during 4weeks after periosteal stimulation in patient scheduled to receive gingival grafts and to compare variations in the gingival blood flow between smoker and non-smoker. Laser Doppler Flowmetry(floLAB(R), Moor Instruments Ltd, England ; wave length = 780mm. Max. power =l.6mW) was used to measure the gingival blood flow. 112 sites of 68 male patients (32 smokers and 36 non-smoker), aged between 23 and 48 years (smoker : 24-44 years. mean=32.6, non-smoker : 23-48 years, mean=28.5) were monitored for the blood flow. Gingival blood flow measured at before periosteal stimulation, 1-, 2-, 3-, and 4-weeks after periosteal stimulation from 10 a.m. to 2 p.m. The difference of blood flow in each measuring time, each measuring site and between smokers and non-smokers were statistically analyzed by MANOVA. The results were as follows : (1) Blood flow stayed increased for 2 weeks, and then, it was a tendency to decrease(p<0.05). (2) There was no statistically significant difference of blood flow change between smokers and non-smokers. (3)The blood flow at middle site had lower than mesial and distal site during the measuring periods(p<0.05). The present study suggested that blood flow change following periosteal stimulation was significant difference, thus periosteal stimulation before gingival graft might induce favorable results in gingival recession patient.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.8
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• pp.717-724
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• 2016

This paper presents design of a 40 GHz CMOS PLL frequency synthesizer for a 60 GHz sliding-IF RF transceiver. For stable locking over a wide bandwith for a injection-locked frequency divider, an inductive-peaking technique is employed so that it ensures the PLL can safely lock across the very wide tuning range of the VCO. Also, Injection-locked type LC-buffer with low-phase noise and low-power consumption is added in between the VCO and ILFD so that it can block any undesirable interaction and performance degradation between VCO and ILFD. The PLL is designed in 65 nm CMOS precess. It covers from 37.9 to 45.3 GHz of the output frequency. and its power consumption is 74 mA from 1.2 V power supply.

• Korean Journal of Veterinary Research
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• v.50 no.2
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• pp.155-160
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• 2010

The objective of this study was to compare wound healing in stomach with $CO_{2}$ laser and scalpel incision by measuring the extent of bleeding, the ease of gastric incision, incision time, degree of adhesion and wound healing degree in dogs. Sixteen healthy dogs were used. Two symmetrical incisions were made in ventral aspect of the stomach between the greater and lesser curvatures were made with scalpel and 0.2 mm spot diameter $CO_{2}$ laser (8W, continuous wave) in sixteen dogs. And then each wound was closed with absorbable suture in a two-layer inverting seromuscular pattern. At 3, 7, 14 and 21 days after initial wounding, each wound was taken for histological observation. On surgery, the extent of bleeding, the ease of incision and incision time showed significant differences between the groups. The $CO_{2}$ laser provided better hemostasis (p < 0.05) and smaller postoperative adhesion compared with the scalpel. However, the scalpel produced faster speed of incision and was easier to handle than the $CO_{2}$ laser (p < 0.05). Although there was no considerable difference between the two groups in histological observation, necrosis and calcium deposit tended to be larger in the $CO_{2}$ laser than in the scalpel.

• Journal of Korean Neurosurgical Society
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• v.29 no.12
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• pp.1634-1641
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• 2000

Objective : The cerebrospinal fluid(CSF) pulsates within the craniospinal axis in response to rhythmic cerebral blood volume variation during the cardiac cycle. The aim of this study is to characterize the normal and abnormal CSF flow and its waveforms in the cervical spinal subarachnoid space. Methods : The magnetic resonance(MR) images were obtained with 1.5 T(GE Signa, GE Medical Systems, Milwaukee, USA) unit using the 2 dimensional cine PC(phase contrast) sequence with cardiac gating and gradient recalled echo imaging. This pulse sequence yielded 16 quantitative flow-encoded images per cardiac cycle. Sagittal and axial images of the cervical spinal CSF space were obtained, and target sites were analyzed for characteristic CSF flow (TR=50ms, TE=12.5-15ms). The region of interest(ROI) was 1mm 3 in volume. Twenty six persons were included in this study : 10 healthy volunteers and 16 patients with cervical myelopathy. The post-operative cine MR study were also done in five patients. Results : The normal CSF pulsation dynamics in the cervical spine showed discrete systolic and diastolic components. The CSF flow revealed a sine wave pattern, in which the systolic phase was shorter than the diastolic phase(ratio=2 : 3). The patient group revealed decreased amplitudes of the CSF flow and irregularly distored flow waves. The systolic phase was elongated in the ROI above the stenotic level, whereas the diastolic phase was lengthened below the level. In the postoperative images, the abnormal pattern and amplitude were found to be corrected. Conclusion : From these results, the authors believe that the CSF flow study provides valuable informations regarding the extent of cervical stenosis and may be useful for the surgical planning and post-operative evaluation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.5
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• pp.508-514
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• 2004

A fluxgate magnetic sensor consists of a solenoid excitation coil, pick-up coil, and magnetic core. We presents the effect of magnetic core shape in a micromachined fluxgate sensor. To observe the performance of fluxgate sensor with magnetic core side width and gap, side width of 125 ${\mu}{\textrm}{m}$, 250 ${\mu}{\textrm}{m}$, and 500 ${\mu}{\textrm}{m}$ were designed in a rectangular-ring shaped core and the gaps of 0 ${\mu}{\textrm}{m}$, 50 ${\mu}{\textrm}{m}$, and 100 ${\mu}{\textrm}{m}$ were also fabricated in a racetrack shaped core. The solenoid coils and magnetic core were separated by benzocyclobutane(BCB) which had high insulation and good planarization characters. Copper coil patterns of 10 ${\mu}{\textrm}{m}$ width and 6${\mu}{\textrm}{m}$ thickness were electroplated on Ti(300 $\AA$) / Cu(1500 $\AA$) seed layers. 3 ${\mu}{\textrm}{m}$ thick N $i_{0.8}$F $e_{0.2.}$(permalloy) film for the magnetic core was also electroplated under 2000 gauss to induce the magnetic anisotropy. The magnetic core had the high DC effective permeability of ∼1,300 and coercive field of ∼0.1 Oe. Because the magnetic cores of 500 ${\mu}{\textrm}{m}$ side width and 0 gap had a low magnetic flux leakage, high sensitivity of ∼350 V/T were measured at excitation condition of 3 $V_{P-P}$ and 2 MHz square wave. The power consumption of ∼14 ㎽ was measured. The fabricated fluxgate sensor had the very small actual size of 3.0${\times}$1.7 $\textrm{mm}^2$. When two fluxgates were perpendicularly aligned in terrestrial field, their two-axis output signals were very useful to commercialize an electronic azimuth compass for the portable navigation system.m.m.m.