• 대한예방의학회:학술대회논문집
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• 1994.02b
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• pp.169-179
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• 1994

B-mode ultrasound is being used to assess carotid atherosclerosis in epidemiological studies and clinical trials. Recently the interpretation of measurements made from ultrasound images has been questioned. This study examines the anatomical correlates of B-mode ultrasound of carotid arteries in vitro and in situ in cadavers. Twenty-seven segments of human carotid artery were collected at autopsy. pressure perfusion fixed in buffered 2.5% gluteraldehyde and 4% paraformaldehyde and imaged using an ATL UM-8 (10 MHz single crystal mechanical probe). Each artery was then frozen, sectioned and stained with van Gieson or elastin van Gieson. The thickness of the intima. media and adventitia were measured 'to an accuracy of 0.01 mm from histological sections using a calibrated eye graticule on a light microscope. Shrinkage artifact induced by histological preparation was determined to be 7.8%. Digitised ultra sound images of the artery wall were analysed off-line. The distance from the leading edge of the first interface ($LE_{1}$) to the leading edge of the second interface ($LE_2$) was measured using a dedicated programme. $LE_{1}$-$LE_{2}$ measurements were correlated against histological measurements corrected for shrinkage. Mean values for the far wall were: ultra sound $LE_{1}$-$LE_{2}$ (0.97 mm, S.D. 0.26), total wall thickness (1.05 mm, S.D. 0.37), adventitia (0.35 mm, S.D. 0.16), media (0.61 mm, S.D. 0.18). intima (0.09 mm, S.D. 0.13). Ultrasound measurements corresponded best with total wall thickness, rather than elastin or the intima-media complex. Excision of part of the intima plus media or removal of the adventitia resulted in a corresponding decrease in the $LE_{1}$-$LE_{2}$ distance of the B-mode image. Furthermore. increased wall thickness due to intimal atherosclerotic thickening correlated well with $LE_{1}$-$LE_{2}$ distance of the B-mode images. B-mode images obtained from the carotid arteries in situ in four cadavers also corresponded best with total wall thickness measured from histological sections and not with the thickness of the intima plus media. In conclusion, the $LE_{1}$-$LE_{2}$ distance measured on B-mode images of the carotid artery best represents total wall thickness of intima plus media plus adventitia and not intima plus media alone.

• Korean Parent-Child Health Journal
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• v.13 no.2
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• pp.95-101
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• 2010

Purpose: This study is intended to identify difference postpartum depression according to delivery mode in the postpartum women. Methods: The subjects were 239 postpartum women in D and A city. Data collected from June 9, 2006 to August 6, 2007 using structured questionnaire surveys and convenience sampling. Measuring instrument was BDI (Beck Depression Inventory) translated By Lee and Song (1991). Collected data was analyzed by $x^2$-test, ANCOVA, Stepwise Multiple Regression with SPSS/PC 14.0. Results: There were significant differences in postpartum period ($x^2$=12.40, p = .002) and sleeping hours ($x^2$=9.09, p = .011) as analysed distribution of the subjects according to delivery mode. As result of analyzing the difference of postpartum depression according to delivery mode using ANCOVA, C-sec women's postpartum depression was higher than vaginal delivery women statistically (F=6.32, p = .013). As a result of Multiple Regression, income was a influencing factor of postpartum depression in vaginal delivery women and support of spouse and sleeping hours were influencing factors in C-sec women. Conclusion: There were differences in postpartum depression and their influencing factors according to delivery mode. Therefore it is necessary to develop and study a concrete nursing intervention and strategies for reducing the postpartum depression according to delivery mode.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.1
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• pp.45-53
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• 2019

In this paper, three types of array antennas for 5G mobile devices operating at 28 GHz were designed, and their performances were compared. The isolation between antenna elements was compared based on $S_{21}$. The $S_{21}$ of dipole, slot, and patch type are -13.76 dB, -16.88 dB, and -11.47 dB, respectively, with the slot-type antenna having the highest isolation. In order to compare the beam coverage performance, several characteristics such as beam width and maximum beam steering angle were analyzed. The analysis shows that the slot type has the widest steering angle of $63^{\circ}$ while the patch type has narrowest with $36^{\circ}$. In addition, to verify the performance of the antennas in the actual usage environment of the device, antenna characteristics in talk mode and data mode were analyzed through simulation. The results confirmed that the slot-type array antenna is the most suitable array antenna element for 28 GHz 5G mobile devices.

• Korean Journal of Optics and Photonics
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• v.8 no.4
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• pp.327-332
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• 1997

We fabricated the high speed 1.55${\mu}{\textrm}{m}$ distributed feedback laser diodes (DFB-LD) using both two-step mesa etching process and semi-insulating InP current blocking layers. The devices characteristics were threshold current of ~15mA, slope efficiency of ~0.13mW/mA, and dynamic resistance of ~6.0Ω, with as-cleaved facets. The fabricated DFB-LD showed the single longitudinal mode with more than 40dB up to 6 $I_{th}$(CW condition), emitting at the wavelength of 0.546${\mu}{\textrm}{m}$. The -3dB bandwidth was >10㎓ at the driving current of 27mA, and the maximum -3dB bandwidth was ~18㎓ at 90 mA current, showing the superior frequency response of SI-PBH DFB-LD. In the 10Gb/s transmission experiment for 1.55${\mu}{\textrm}{m}$ DFB-LD module, maximum 10 km of single mode fiber(SMF) or 80 km of dispersion shifted fiber (DSF) could be transmitted with error free.

• Journal of electromagnetic engineering and science
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• v.14 no.2
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• pp.61-67
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• 2014

This paper presents a zero-IF CMOS RF receiver, which supports three channel bandwidths of 5/10/40MHz for LTE-Advanced systems. The receiver operates at IMT-band of 2,500 to 2,690MHz. The simulated noise figure of the overall receiver is 1.6 dB at 7MHz (7.5 dB at 7.5 kHz). The receiver is composed of two parts: an RF front-end and a baseband circuit. In the RF front-end, a RF input signal is amplified by a low noise amplifier and $G_m$ with configurable gain steps (41/35/29/23 dB) with optimized noise and linearity performances for a wide dynamic range. The proposed baseband circuit provides a -1 dB cutoff frequency of up to 40MHz using a proposed wideband OP-amp, which has a phase margin of $77^{\circ}$ and an unit-gain bandwidth of 2.04 GHz. The proposed zero-IF CMOS RF receiver has been implemented in $0.13-{\mu}m$ CMOS technology and consumes 116 (for high gain mode)/106 (for low gain mode) mA from a 1.2 V supply voltage. The measurement of a fabricated chip for a 10-MHz 3G LTE input signal with 16-QAM shows more than 8.3 dB of minimum signal-to-noise ratio, while receiving the input channel power from -88 to -12 dBm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.8-13
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• 2016

A pattern-switchable origami antenna is designed with paper using inkjet-printing technology. The proposed antenna can be switched between loop and dipole antenna modes by folding and unfolding the paper, respectively. The proposed antenna is designed for the resonant frequencies of both modes to be 1.85 GHz. Eutectic gallium-indium liquid metal is introduced in order to avoid cracks in the conductive ink when the paper is folded. The performance of the proposed antenna is demonstrated through simulation and measurement results and antenna gain of dipole-mode and loop-mode are -4 dBi and -5 dBi, respectively. Also, the nulls of both dipole and loop modes compensate nulls from each mode.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.7
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• pp.532-538
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• 2003

This paper studies on the noise reduction for a small automobile DC Motor (a window motor) using the 6 sigma process. The application of 6 sigma process suggested reliable and valuable statistical data for the quality of the DC motor at the production line. In the measurement step in 6 sigma process. the FMEA(failure mode effect analysis) were used for the detection of noise sources. The application of 6 sigma Process gave not only the improving method for the quality of the DC motor but also the confidence of improvement Itself since it was done on the basis of the test results for a number of DC motors at the production line. Consequently the 6 sigma process was proved very effective for the noise reduction at the production line.

• Journal of Power Electronics
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• v.13 no.3
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• pp.381-389
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• 2013

A method to control the speed or the torque of a permanent-magnet direct current motor is presented. The rotor speed and the external torque estimation are simultaneously provided by appropriate observers. The sensorless control scheme is based on current measurement and switching states of power devices. The observers performances are dependent on the accurate machine parameters knowledge. Sliding mode control approach was adopted for drive control, providing the suitable switching states to the chopper power devices. Despite the predictable chattering, a convenient first order switching function was considered enough to define the sliding surface and to correspond with the desired control specifications and drive performance. The experimental implementation was supported on a single dsPIC and the controller includes a logic overcurrent protection.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.10 s.352
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• pp.111-117
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• 2006

Reconfigurable CMOS low-noise amplifier (LAN) has been developed for multi-mode/multi-band wireless receiver. By employing common-gate input stage, the performance can be optimized for multiple operation bands by simply controlling the output load impedance. Although the conventional common-gate LAN has larger than 3dB noise figure (NF), the newly developed negative feedback scheme enables the common-gate input LNA to have less than 2dB NF. To have optimum linearity performance of wireless receiver, the gain of the LNA can be controlled. The LNA implemented in a 0.13mm CMOS technology shows $19{\sim}20dB$ voltage gain, $1.7{\sim}2.0dB$ NF, -2dBm iIP3 at $1.8{\sim}2.5GHz$ frequency range. The LNA dissipates 7mW from a 1.2V supply voltage.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.3
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• pp.302-309
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• 2024

This study estimates the target strength of anchovy Engraulis japonicus required for studying their distribution and density using acoustics and evaluates the acoustic scattering characteristics of anchovies by frequency using the Kirchoff ray mode (KRM) model. The experiment was conducted on 30 anchovies with 4.7-21.5 cm total length. The maximum TS_cm (Simming angle, 9.1°; standard deviation, ± 13.1°) according to total length was -66.9, -65.2, -64.4, and -63.4 dB at 38, 70, 120, and 200 kHz, respectively. The average TS_cm (Simming angle: 9.1°, standard deviation: ± 13.1°) according to total length was -68.9, -68.8, -69.6, and -70.0 dB at 38, 70, 120, and 200 kHz, respectively. The results of this study provide an important basis for future studies that use acoustics to estimate the target strength of anchovies.