• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.2
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• pp.25-34
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• 2010

This paper proposed a high-speed voltage-controlled ring-oscillator(VCRO) using a frequency doubling technique. The design of the proposed oscillator has been based on TSMC 0.18um 1.8V CMOS technology. The frequency doubling technique is achieved by AND-OR operations with 4 signals which have $90^{\circ}$ phase difference one another in one cycle. The proposed technique has been implemented using a 4-stage differential oscillator compose of differential latched inverters and NAND gates for AND and OR operations. The differential ring-oscillator can generate 4 output signals, which are $90^{\circ}$ out-of-phase one another, with low phase noise. The ANP-OR operations needed in the proposed technique are implemented using NAND gates, which is more area-efficient and provides faster switching speed than using NOR gates. Simulation results show that the proposed, VCRO operates in the frequency range of 3.72 GHz to 8 GHz with power consumption of 4.7mW at 4GHz and phase noise of ~-86.79dBc/Hz at 1MHz offset. Therefore, the proposed oscillator demonstrates superior performance compared with previous high-speed voltage-controlled ring-oscillators and can be used to build high-performance frequency synthesizers and phase-locked loops for radio-frequency applications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.880-886
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• 2007

We have proposed a new "hybrid" envelope elimination and restoration(EER) transmitter architecture using an efficiency optimized power amplifier(PA) and modified bias modulator. The efficiency of the PA at the average drain voltage is very important for the overall transmitter efficiency because the PA operates mostly at the average power region of the modulation signal. Accordingly, the efficiency of the PA has been optimized at the region. Besides, the bias modulator has been accompanied with the emitter follower for the minimization of memory effect. A saturation amplifier, class $F^{-1}$ is built using a 5-W PEP LDMOSFET for forward-link single-carrier wideband code-division multiple-access(WCDMA) at 1-GHz. For the interlock experiment, the bias modulator has been built with the efficiency of 64.16% and peak output voltage of 31.8 V. The transmitter with the proposed PA and bias modulator has been achieved an efficiency of 44.19%, an improvement of 8.11%. Besides, the output power is enhanced to 32.33 dBm due to the class F operation and the PAE is 38.28% with ACLRs of -35.9 dBc at 5-MHz offset. These results show that the proposed architecture is a very good candidate for the linear and efficient high power transmitter.

• Journal of Korean Academy of Nursing
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• v.29 no.4
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• pp.903-916
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• 1999

The purpose of this study was to compare the ear-based rectal temperature measured with a tympanic thermometer with the rectal temperature measured with a glass mercury thermometer in order to test the accuracy of tympanic thermometer and to determine relationship among rectal, axilla, and abdominal temperature in neonates. The samples consisted of thirty four neonates admitted to the neonatal intensive care unit and nursery at an university affiliated hospital. The mean age of the subjects was 4.9 days. The ear-based rectal temperatures were taken with a tympanic thermometer in rectal mode (First Temp Genius 3000). Rectal and axilla temperatures were taken with a glass mercury thermometer, Abdominal temperature was continuously monitored with the probe connected to the servo controller of incubator. The results of the study can be summarized as follows : 1. Intrarater comparison : Agreement between the first and the second ear-based rectal temperature was 97% within 0.1$^{\circ}C$. 2. Comparison of ear-based rectal temperature and the rectal temperature from a glass mercury thermometer : ear-based rectal temperature ranged from 36.95$^{\circ}C$d to 37.95$^{\circ}C$, with a mean of 37.58$^{\circ}C$(SD＝0.22$^{\circ}C$). Rectal temperature from a glass mercury thermometer ranged from 36.2$0^{\circ}C$ to 37.2$0^{\circ}C$, with a mean 36.75$^{\circ}C$(SD＝0.29). The mean difference between both temperatures was 0.84$^{\circ}C$. The correlation coefficient between both temperatures was r＝0.77(p＝0.00). 3. Comparison of rectal and axilla temperature : Axilla temperature ranged from 35.8$0^{\circ}C$ to 37.1$0^{\circ}C$, with a mean of 36.55$^{\circ}C$. The mean absolute difference between the rectal and axilla temperature was 0.23$^{\circ}C$. The correlation coefficient between rectal and axilla was r＝0.67. 4. Comparison of axilla and abdominal temperature : Abdominal temperature ranged from 36.2$0^{\circ}C$ to 37.0$0^{\circ}C$, with a mean of 36.58$^{\circ}C$. The mean absolute difference between axilla and abdominal temperature was only -0.03$^{\circ}C$. Findings of this study suggest that ear-based rectal temperature overestimates the actual rectal temperatures in neonates. Therefore, the interchangeble use of both temperatures in clinics seems problematic. The site offset(adjustment value) programmed in rectal mode of the tympanic thermometer needs to be readjusted. Choosing one optimal site for temperature measurement for each patient, and using the specific site consistently would result in more consistent measurements of changes in body temperature, and thus can be more effective in diagnosing fever or hypothermia.

• Journal of the Korean Wood Science and Technology
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• v.29 no.4
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• pp.1-8
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• 2001

This study was carried out to investigate the strength and stiffness of drift pinned and bolted joints with steel-plates by the tension-type lateral strength tests. Specimens were solid wood of Pinus densiflora. Bolt and drift pin were jointed with inserted steel plates. Tests were conducted with combinations of two loading directions (parallel to the grain : 0 degree, perpendicular to the grain : 90 degree) and three diameters of fasteners (d = 6 mm, 10 mm, 12 mm). The results obtained were as follow: 1. In the test of the parallel to the grain, maximum loads were increased with increasing of the diameter of bolt and drift pin in the same end distance. In the test of perpendicular to the grain with diameter 10 mm and 12 mm, specimens mostly were failed with horizontal splits in woods reaching the yield load of drift pinned and bolted joints. 2. The ratio of maximum load to the yield load determined by the so-called "5% offset method", was great in bolted joints in the parallel to the grain This trend become more remarkable as the slenderness ratio was increased. 3. The calculated yield strength was agreed well with the experimental results of drift pinned joint(0 degree).

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.259-271
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• 2013

The purpose of this study was to make the stress distribution produced by simulated different load under two types of internal connection implant system (stepped and tapered type) by means of 3D finite element analysis, The finite element model was designed with the parallel placement of the one fixtures ($4.0mm{\times}11.5mm$) with reverse buttress thread on the mandibular 1st molar. Two models were loaded with 200 N magnitude in the vertical direction on the central position of the crown, the 1.5 mm and 3 mm buccal offset point from the central position of the fixture. The oblique load was applied at the angle of $30^{\circ}$ on the crown surface. Von Mises stress value was recorded and compared in the fixture-bone interface in the bucco-lingual dimension. The results were as follows; 1. The loading conditions of two internal connection implant systems (stepped and tapered type) were the main factor affecting the equivalent bone strain, followed by the type of internal connections. 2. The stepped model had more mechanical stability with the reduced max. stress compared to $11^{\circ}$ tapered models under the distributed oblique loading. 3. The more the contact of implant-abutment interface to the inner wall of implant fixture, the less stress concentration was reduced.

• Geophysics and Geophysical Exploration
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• v.9 no.2
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• pp.139-147
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• 2006

We had conducted a numerical modeling to investigate seismic properties of gas hydrate with field parameters acquired over the East sea in 1998. We used a 2-D staggered grid finite difference method to generate synthetic elastic seismograms for multi-channel seismic survey, OBC (Ocean Bottom Cable) survey and VCS (Vertical Cable Seismic) survey. The results of this study showed that the method using staggered grid yielded stable results and could be used to seismic imaging. We could find out the high amplitude anomaly and the phase reversal phenomenon of reflection wave at interface between the gas hydrate layer and free gas layer such a BSR (Bottom Simulating Reflector) which is the evidence for existence of gas hydrate in seismic reflection data. And we computed the reflection coefficients at the incident angles corresponding to offset distance with the synthetic seismograms. The reflection coefficients acquired from the numerical modeling were nearly consistent with the reflection coefficient computed by Shuey's equation.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.4
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• pp.257-268
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• 2003

The purpose of this study was to assess the loading distributing characteristics of implant prosthesis according to position and direction of load, under vertical and inclined loading using FEA analysis. The finite element model was designed according to standard fixture (4.1mm restorative component x 11.5mm length). The crown for mandibular first molar was made using UCLA abutment. Each three-dimensional finite element model was created with the physical properties of the implant and surrounding bone. This study simulated loads of 200N at the central fossa in a vertical direction (loading condition A), 200N at the outside point of the central fossa with resin filling into screw hole in a vertical direction (loading condition B), 200N at the centric usp in a $15^{\circ}$ inward oblique direction (loading condition C), 200N at the in a $30^{\circ}$ inward oblique direction (loading condition D) or 200N at the centric cusp in a $30^{\circ}$ outward oblique direction (loading condition E) individually. Von Mises stresses were recorded and compared in the supporting bone, fixture, and abutment screw. The following results have been made based on this study: 1. Stresses were concentrated mainly at the ridge crest around implant in both vertical and oblique loading but stresses in the cancellous bone were low in both vertical and oblique loading. 2. Bending moments resulting from non-axial loading of dental implants caused stress concentrations on cortical bone. The magnitude of the stress was greater with the oblique loading than with the vertical loading. 3. An offset of the vertical occlusal force in the buccolingual direction relative to the implant axis gave rise to increased bending of the implant. 4. The relative positions of the resultant line of force from occlusal contact and the center of rotation seems to be more important. 5. The magnitude of the stress in the supporting bone, fixture and abutment screw was greater with the outward oblique loading than with the inward oblique loading and was the greatest under loading at the centric cusp in a $30^{\circ}$ outward oblique direction. Conclusively, this study provides evidence that bending moments resulting from non-axial loading of dental implants caused stress concentrations on cortical bone. But it seems to be more important that how long is the distance from center of rotation of the implant itself to the resultant line of force from occlusal contact(leverage). The goal of improving implants should be to avoid bending of the implant.

• Journal of Dental Rehabilitation and Applied Science
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• v.21 no.1
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• pp.1-14
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• 2005

The purpose of this study was to assess the loading distributing characteristics of implant prosthesis of internal connection system(ITI system) according to position and direction of load, under vertical and inclined loading using finite element analysis (FEA). The finite element model of a synOcta implant and a solid abutment with $8^{\circ}$ internal conical joint used by the ITI implant was constructed. The gold crown for mandibular first molar was made on solid abutment. Each three-dimensional finite element model was created with the physical properties of the implant and surrounding bone. This study simulated loads of 200N at the central fossa in a vertical direction (loading condition A), 200N at the outside point of the central fossa with resin filling into screw hole in a vertical direction (loading condition B), 200N at the centric cusp in a $15^{\circ}$ inward oblique direction (loading condition C), 200N at the in a $30^{\circ}$ inward oblique direction (loading condition D) or 200N at the centric cusp in a $30^{\circ}$ outward oblique direction (loading condition E) individually. Von Mises stresses were recorded and compared in the supporting bone, fixture, and abutment. The following results have been made based on this study: 1. Stresses were concentrated mainly at the ridge crest around implant under both vertical and oblique loading but stresses in the cancellous bone were low under both vertical and oblique loading. 2. Bending moments resulting from non-axial loading of dental implants caused stress concentrations on cortical bone. The magnitude of the stress was greater with the oblique loading than with the vertical loading. 3. An offset of the vertical occlusal force in the buccolingual direction relative to the implant axis gave rise to increased bending of the implant. So, the relative positions of the resultant line of force from occlusal contact and the center of rotation seems to be more important. 4. In this internal conical joint, vertical and oblique loads were resisted mainly by the implant-abutment joint at the screw level and by the implant collar. Conclusively, It seems to be more important that how long the distance is from center of rotation of the implant itself to the resultant line of force from occlusal contact (leverage). In a morse taper implant, vertical and oblique loads are resisted mainly by the implant-abutment joint at the screw level and by the implant collar. This type of implant-abutment connection can also distribute forces deeper within the implant and shield the retention screw from excessive loading. Lateral forces are transmitted directly to the walls of the implant and the implant abutment mating bevels, providing greater resistance to interface opening.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.2
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• pp.21-31
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• 2010

This paper presents a design of PLL and SSCG for reducing the EMI effect at the electronic machinery and tools for DisplayPort application. This system is composed of the essential element of PLL and Charge-Pump2 and Reference Clock Divider to implement the SSCG operation. In this paper, 270MHz/162MHz dual-mode PLL that can provide 10-phase and 1.35GHz/810MHz PLL that can reduce the jitter are designed for 2.7Gbps/162Gbps DisplayPort application. The jitter can be reduced drastically by combining 270MHz/162MHz PLL with 2-stage 5 to 1 serializer and 1.35GHz PLL with 2 to 1 serializer. This paper propose the frequency divider topology which can share the divider between modes and guarantee the 50% duty ratio. And, the output current mismatch can be reduced by using the proposed charge-pump topology. It is implemented using 0.13 um CMOS process and die areas of 270MHz/162MHz PLL and 1.35GHz/810MHz PLL are $650um\;{\times}\;500um$ and $600um\;{\times}\;500um$, respectively. The VCO tuning range of 270 MHz/162 MHz PLL is 330 MHz and the phase noise is -114 dBc/Hz at 1 MHz offset. The measured SSCG down spread amplitude is 0.5% and modulation frequency is 31kHz. The total power consumption is 48mW.