• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.11
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• pp.66-70
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• 2016

This paper presents an 24 GHz I/Q LO generator for a heartbeat measurement radar system. In order to improve the mismatch performance between I and Q LO signals against process variation, a 24 GHz I/Q LO generator employing a low-pass phase shifter and a high-pass phase shifter composed of inductors and capacitors is proposed. The proposed 24 GHz I/Q LO generator consists of an LO buffer, a low-pass phase shifter and a high-pass phase shifter. It was designed using a 65 nm CMOS technology and draws 8 mA from a 1 V supply voltage. The proposed 24 GHz I/Q LO generator shows a gain of 7.5 dB, a noise figure of 2.3 dB, 0.1 dB gain mismatch and $4.3^{\circ}$ phase mismatch between I and Q-path against process and temperature variations for the operating frequencies from 24.05 GHz to 24.25 GHz.

• Journal of Korean Society of Forest Science
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• v.85 no.3
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• pp.443-452
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• 1996

A study has been made to estimate biomass and NPP based on equation form of $Wt=aD^bH^c$ for Quercus variabilis and Quercus mongolica natural stands(Mean age; 67, 62yrs old) in Chungju. Equation form of $Wt=aD^bH^c$ was more adequate than $Wt=a(D^2H)^b$ and $Wt=aD^b$ for the estimation of the biomass and NPP. Individual biomass was compared using a paired t-test by tree component which showed no significant differences. Total aboveground biomass of Quercus mongolica was 130.6 t/ha and that of Quercus variabilis was 137.4 t/ha. Biomass of Q. mongolica was composed of foliage 5.1 t/ha(3.9%), dead branch 3.5 t/ha(2.7%), live branch 29.7 t/ha(23.0%), bolebark 16.2 t/ha(12.5%), and bolewood 74.9 t/ha(58.0%), and that of Q. variabilis was composed of foliage 3.8 t/ha(2.9%), dead branch 2.9 t/ha(2.2%), live branch 24.3 t/ha(18.4%), bolebark 20.4 t/ha(15.5%), and bolewood 80.4 t/ha(61.0%). Net primary production was 10.0 t/ha/yr in the Q. mongolica stand and 8.6 t/ha/yr in the Q. variabilis stand, respectively. Net primary production of Quercus forest in Chungju was very close to the mean NPP of the broadleaved forest of temperate zone.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.202-207
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• 2010

In this paper, a novel voltage-controlled oscillator(VCO) using the open loop multiple split ring resonator(OLMSRR) is presented for improving the phase noise, implemented in 130 nm CMOS technology. Compared with the conventional CMOS LC resonator, the proposed CMOS OLMSRR has the larger coupling coefficient value, which makes a higher Q-factor, and has improved the phase noise of the VCO. The proposed CMOS VCO based OLMSRR has the phase noise of -99.67 dBc/Hz @ 1 MHz in the oscillation frequency. Compared with the VCO using the conventional CMOS LC resonator and the proposed VCO using the CMOS OLMSRR structure has been improved in 7 dB. The prototype 24 GHz CMOS VCO is implemented in 130 nm CMOS and occupies a compact die area of $0.7\;mm{\times}0.9\;mm$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.1
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• pp.143-151
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• 2000

In order to clarify the effect of tube orientation on pool boiling heat transfer, the experiments were carried out for the saturated pool boiling of water at atmospheric pressure. Through the tests a series of data sets for heat flux versus wall superheat has been obtained using various combinations of tube diameters (D=9.7 $\~$25.4mm)， surface roughness ($\varepsilon$=15.1$\~$60.9nm)， and tube orientations (horizontal and vertical). ηei experimental results show that the slope of heat flux versus wall superheat becomes smaller than that of the horizontal tube as the surface roughness decreases from $\varepsilon$=60.9 to $\varepsilon$=15.1nm. Such that， two curves for the horizontal and vertical tubes cross each other in accordance with surface roughness and the crossing point can be suggested as q" = ‘-4.768+1.334$\varepsilon$+0.055${\varepsilon}^2$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1167-1172
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• 2013

This paper presents a X-band doppler radar with high conversion gain using a self-oscillating-mixer(SOM) that oscillation and frequency mixing is realized at the same time. To improve phase noise of the SOM oscillator, a ${\lambda}/2$ slotted square patch resonator(SSPR) was proposed, which shows high Q-factor of 175.4 and the 50 % reduced circuit area compared to the conventional resonator. To implement the low power system, low biasing voltage of 1.7 V was supplied. To enhance the conversion gain of the SOM, bias circuit is configured near the pinch-off region of transistor, and the conversion gain was optimized. The output power of the proposed SOM was -3.16 dBm at 10.65 GHz. A high conversion gain of 9.48 dB was obtained whereas DC Power consumption is relatively low about 7.65 mW. The phase noise is -90.91 dBc/Hz at 100 kHz offset. The figure-of-merit(FOM) of the proposed SOM was measured as -181.8 dBc/Hz, which is supplier to other SOMs by more than about 7 dB.

• BMB Reports
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• v.37 no.5
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• pp.522-526
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• 2004

Prader-Willi (PWS) and Angelman (AS) are syndromes of developmental impairment that result from the loss of expression of imprinted genes in the paternal (PWS) or maternal (AS) 15q11-q13 chromosome. Diagnosis on a clinical basis is difficult in newborns and young infants; thus, a suitable molecular test capable of revealing chromosomal abnormalities is required. We used a variety of cytogenetic and molecular approaches, such as, chromosome G banding, fluorescent in situ hybridization, a DNA methylation test, and a set of chromosome 15 DNA polymorphisms to characterize a cohort of 27 PWS patients and 24 suspected AS patients. Molecular analysis enabled the reliable diagnosis of 14 PWS and 7 AS patients, and their classification into four groups: (A) 6 of these 14 PWS subjects (44%) had deletions of paternal 15q11-q13; (B) 4 of the 7 AS patients had deletions of maternal 15q11-q13; (C) one PWS patient (8%) had a maternal uniparental disomy (UPD) of chromosome 15; (D) the remaining reliably diagnoses of 7 PWS and 3 AS cases showed abnormal methylation patterns of 15q11-q13 chromosome, but none of the alterations shown by the above groups, although they may have harbored deletions undetected by the markers used. This study highlights the importance of using a combination of cytogenetic and molecular tests for a reliable diagnosis of PWS or AS, and for the identification of genetic alterations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.10A
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• pp.1563-1570
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• 1999

This paper relates to the soft decision method with erasure technique in digital terrestrial television broadcasting system. The proposed decoder use the CSI derived from using the pilots in receiver. The active real(I) and imaginary(Q) data are transferred to the branch metric calculation block that decides the Euclidean distance for the soft decision decoding and also the estimated CSI values are transferred to the same block. After calculating the Euclidean distance for the soft decision decoding, the Euclidean distance of branch metric is multiplied by CSI. To do so, new branch metric values that consider each carrier state information are obtained. We simulated this method in better performance of about 0.15dB to 0.17dB and 2.2dB to 2.9dB in Rayleigh channel than that of the conventional soft decision Viterbi decoding with or without bit interleaver where the constellation is QPSK, 16-QAM and 64-QAM.

• Journal of Korean Society of Forest Science
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• v.87 no.3
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• pp.445-458
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• 1998

The present study focused on the vegetation structure and dynamics of Betula davurica forest were to provide the information for management, distribution and utilization of B. davurica forest in Mt. Chiri national park, southern Korea. The layer structure of B. davurica forest were consist of tree layer(18 species), middle layer(29 species), shrub layer(43 species) and herb layer(68 species). According to the importance value of stratification of layers, In tree layer, B. davurica dominant the highest value of 123.97%, Alnus hirsuta 49.04., Castanea crenata 25.58%, Quercus serrata 25.02%, Stewartia koreana 14.49%, in middle layer were B. davurica 70.81%, Q. serrata 37.74%, Fraxinus rhynchophylla 25.35% Lindera erythrocarpa 24.52%, S. koreana 18.86%, shrub layer were Sasa borealis 28.28%, L. erythrocarpa 24.94%, Rhus trichocarpa, 20.42%, Stephanandra incisa 19.90% and herb layer Schizandra chinensis 18.51%, Aster scaber 12.26%. Disporum smilacinum 10.63% etc, respectively. Results of chi-square test statistics based on presence-absence parameters, the positively associated species pair were Quercus variablis - Q. acutissima, Stewartia koreana - Symplocos paniculata, Acer pseudo-sieboldianum - Quercus mongolica. And covariation was calculated based on quantitative measure of density. The results showed that the association and covariation values among species not agreed with each other. The frequency distribution of DBH Betula davurica species showed reverse J-shaped, therefore it's seems to retrain as a dominant species. When predicting succession in Betula davurica forest, it is seedling and saplings were not richness, succession was governed by competition of hardwood species of subtree and tree layer.

• The Transactions of the Korea Information Processing Society
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• v.4 no.9
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• pp.2378-2390
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• 1997

We, in this paper, have implemented E1 HDSL(high-bit-rate digital subscriber line) function over an ATM switching system. The maximum loop lengths for subscriber service and cell loss rates to meet the bit error rate of $10^{-7}$ at transmission of 2B1Q HDSL data of E1 rate over existing telephone copper wires in the presense of the significant impairments such as crosstalk, impulse noise, power line noise and longitudinal over the CSAs environment consisting of 26 gauge and 24 gauge unloaded copper telephone lines has assessed. We have confirmed the typical media services function such as video on demand(VOD) service for MPEG-1, image conference service and high-speed Internet access service over ATM switching system.

• Korean Journal of Plant Resources
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• v.10 no.1
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• pp.64-85
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• 1997

This study was to establish the floristic composition and vegetation of resources vascular plants of Mt. Mandukbong(1,035.3 m; $128^{\circ}$54'24'E, $37^{\circ}$36'53'N). This work were investigated during the period of 1996. Resources vascular plants were composed of 97 families, 298 genera, 406 species, 70 varieties and 8 formae, Totaling 484 taxa. Among the investigated resources plants. 15 taxa(2.6%) were Korean endemic species. The forest were comparatively well conservated by Pteridophyta calculation(Pte-Q), 1.1 Useful of resources plants were Edible source(46.7%), Pasture source(37.2%), Medicinal source(35.5%), Ornamental source(12.1%)and Timber source(5.9%) respectively. The forest vegetion was classified into 1 order, 1 alliances, 1 suballiances and 4 communities; Rhododendro - Quercetalia mongolicae Kim 1990 Lindero - Quercion mongolicae Kim 1990 A. Typical community B. Quercus variablilis - Quercus mongolica Community Callicarpo - Quercenion serratae Kim 1990 C. Carex humilis v. nana - Pinus densiflora Community D. Juglans mandshurica - Urtica angustifloia community