• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1469-1473
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• 2010

Influences of alrylamino (R) substituents on the herbicidal activity ($pI_{50}$) of 1-(4-chloro-2-fluoro-5-propargyloxypheny)-3-(R)-thiourea analogues (1 ~ 35) against the barnyard grass (Echinochloa crusgalli) in the pre-emergence step were discussed quantitatively using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) as the three dimensional quantitative structure-activity relationship (3D-QSAR) method. The statistically most satisfactory CoMFA models for the herbicidal activity against the barnyard grass had the better predictability ($r^2{_{cv.}}$) and correlativity ($r^2{_{ncv.}}$) than those of CoMSIA models. The optimized CoMFA model 1($r^2{_{cv.}}$ = 0.531 & $r^2{_{ncv.}}$ = 0.931) with the sensitivity to the perturbation (${d_q}^{2'}{dr^2}_{yy'}$ = 1.081) and the prediction ($q^2$ = 0.475) produced by a progressive scrambling analyses were not dependent on chance correlation. And statistical qualities with the atom based fit alignment (AF) were slightly higher than those of the field fit alignment (FF). According to the optimized CoMFA model 1, the contribution ratio (%) of the steric field (76.9%) on the herbicidal activity of the Thioureas was three-fold higher than that of the electrostatic field (20.1%) and the hydrophobic field (3.0%) had the least influence. A steric favor group is on the vicinity of the nitrogen atom in alrylamino (R) substituent, and a steric disfavor group is on the outer side of alrylamino (R) substituent. Thus, as the size of alrylamino (R) substituent increases, so does the herbicidal activity of the substituent.

• Journal of the Korean Mathematical Society
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• v.56 no.6
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• pp.1515-1528
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• 2019

We show that large subsets of vector spaces over finite fields determine certain point configurations with prescribed distance structure. More specifically, we consider the complete graph with vertices as the points of $A{\subseteq}F^d_q$ and edges assigned the algebraic distance between pairs of vertices. We prove nontrivial results on locating specified subgraphs of maximum vertex degree at most t in dimensions $d{\geq}2t$.

• Journal of Integrative Natural Science
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• v.4 no.3
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• pp.210-215
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• 2011

Holographic quantitative structure-activity relationships (HQSAR) is a useful tool to correlates structures with their biological activities. HQSAR is a two dimensional (2D) QSAR methodology, which generates QSAR equations through 2D fingerprint and correlates it with biological activity. Here, we report a 2D-QSAR model for a series of fifty-one 3,4-dihydroxychalcones derivatives utilizing HQSAR methodology. We developed HQSAR model with 6 optimum numbers of components (ONC), which resulted in cross-validated correlation coefficient ($q^2$) of 0.855 with 0.283 standard error of estimate (SEE). The non-cross-validated correlation coefficient (r2) with 0.966 indicates the model is predictive enough for analysis. Developed HQSAR model was binned in to a hologram length of 257. Atomic contribution map revealed the importance of dihydroxy substitution on phenyl ring.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.11 s.353
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• pp.83-89
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• 2006

This paper describes the design of I/Q channel 12bit Digital-to-Analog Converter(DAC) which shows the conversion rate of 120MHz and the power supply of 3.3V with 0.35um CMOS n-well 1-poly 4-metal process for advanced wireless transceiver. The proposed DAC utilizes 4-bit thermometer decoder with 3 stages for minimum glitch energy and linearity error. Also, using a optimized 4bit thermometer decoder for the decrement of the chip area. Integral nonlinearity(INL) of ${\pm}1.6LSB$ and differential nonlinearity(DNL) of ${\pm}1.3LSB$ have been measured. In single tone test, the ENOB of the proposed 12bit DAC is 10.5bit and SFDR of 73dB(@ Fs=120MHz, Fin=1MHz) is measured, respectively. Dual-tone test SFDR is 61 dB (@ Fs=100MHz, Fin=1.5MHz, 2MHz). Glitch energy of 31 pV.s is measured. The converter consumes a total of 105mW from 3.3-V power supply.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.5
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• pp.675-681
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• 2016

A 41dB gain control range $6^{th}$-order band-pass receiver front-end (RFE) using CMOS switched frequency translated impedance (FTI) is presented in a 40 nm CMOS technology. The RFE consists of a frequency tunable RF band-pass filter (BPF), IQ gm cells, and IQ TIAs. The RF BPF has wide gain control range preserving constant filter Q and pass band flatness due to proposed pre-distortion scheme. Also, the RF filter using CMOS switches in FTI blocks shows low clock leakage to signal nodes, and results in low common mode noise and stable operation. The baseband IQ signals are generated by combining baseband Gm cells which receives 8-phase signal outputs down-converted at last stage of FTIs in the RF BPF. The measured results of the RFE show 36.4 dB gain and 6.3 dB NF at maximum gain mode. The pass-band IIP3 and out-band IIP3@20 MHz offset are -10 dBm and +12.6 dBm at maximum gain mode, and +14 dBm and +20.5 dBm at minimum gain mode, respectively. With a 1.2 V power supply, the current consumption of the overall RFE is 40 mA at 500 MHz carrier frequency.

• Magazine of the Korean Society of Agricultural Engineers
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• v.20 no.1
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• pp.4575-4591
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• 1978

In order to investigate the effects of grain size distribution, cement content, and molding pressure on the strength and durability of soil-cement mixtures, a laboratory test of soil cement mixtures was performed at four levels of cement content, five levels of molding pressure, and four levels of normal curing periods. The results are summarized as follows: 1. Optimum moisture contents in loam soil and maximum dry density in sand soil increased with the increase of cement content, but in others, both optimum moisture contents and maximum dry density were changed ununiformly. 2. When the specimens were molded with molding pressure, 50kg/$\textrm{cm}^2$, strength of soil cement mixture with cement content, 2 and 4 per cent, was lower than the strength of soil cement mixture without cement content by more than 40 to 50 per cent. 3. The strength of soil-cement molded with molding pressure, 100kg/$\textrm{cm}^2$, was higher than the strength of soil-cement molded with M.D.D. obtained from standard compaction test more than 40 per cent in sand loam cement and 50 per cent in loamy cement. 4. There was highly significant positive correlation among molding pressure, cement content and unconfined compressive strentgh and so the following multiple regression equations were obtained. Loam: fc=1.9693C+0.197P-0.84 Sandy loam: fc=2.9065C+0.235P-0.77 5. When the specimens were molded with molding pressure, 20 to 100kg/$\textrm{cm}^2$, the regression equation between the 28-day and 7-day strenght was obtained as follows. Loam : q28=1.1050q7+7.59(r=0.9147) Sandy loam : q28=1.3905q7+3.17 (r=0.9801) 6. At the cement contents of above 50 per cent, the weight losses by freeeze-thaw test were negligible. At the cement content of below 8 per cent the weight losses were singnificantly high under low molding pressure and remarkably decreased with the increase of molding pressure up to 80kg/$\textrm{cm}^2$. 7. Resistance to damage from water and to absorption of water were not improved by molding pressure alone, but when the soil was mixtured with cement above 6 per cent, damage seldoms occurred and absorbed less than 5 per cent of water. 8. There was highly significant inverse-corelationship between the compressive strength of soil cement mixtures and their freeze-thaw loss as well as water absorption. By the regression equation methods, the relationships between them were expessed as followed fc=-7.3206Wa+115.6(r=0.9871) log fc=-0.0174L+1.59(r=0.7709) where fc=unconfined compressive stregth after 28-days curing. kg/$\textrm{cm}^2$ Wa=water absorption, % L : freeze-thaw loss rate, %

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.1009-1014
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• 2012

This paper has proposed a 2,500 MHz ~ 2,570 MHz 0.13-${\mu}m$ CMOS RF front-end transmitter for LTE-Advanced systems. The proposed RF front-end transmitter is composed of a quadrature up-conversion mixer and a driver amplifier. The measurement results show the maximum output power level is +6 dBm and the suppression ratio for the image sideband and LO leakage are better than -40 dBc respectively. The fabricated chip consumes 36 mA from a 1.2 V supply voltage.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.3
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• pp.45-57
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• 2016

This study was focused on the northernmost limit of the distribution changing of Daphniphyllum macropodum and studied characteristic of plant communities of natural monument No. 91 in Najangsan national park, Korea. The results of this study were as follows : 1. The highest importance percentage(I.P.) value at tree layer in Quercus. mongolica community was Q. mongolica, 37.8%. But the highest value of mean importance percentage(M.I.P.) was D. macropodum, 32.8%. 2. The highest I.P. value at tree layer in Carpinus laxiflora community was C. laxiflora, 47.4%. The highest M.I.P. value was C. laxiflora, 28.8% and M.I.P. value of D. macropodum was 24.0%. 3. The highest I.P. value at tree layer in D. macropodum community was D. macropodum, 55.6%. C. laxiflora and Q. mogolica I.P. value was 14.8% and 6.8%, respectively. The highest M.I.P. value was D. macropodum, 47.9%. Sapium japonicum and C. laxiflora M.I.P. value was 11.4% and 10.7%, respectively. 4. The highest I.P. value at tree layer in Quercus variabilis community was C. laxiflora, 20.8%. Q. variabilis and Acer pseudosieboldianum I.P. value was 15.3% and 12.5%, respectively. The highest M.I.P. value was D. macropodum, 21.5%. It needs to the continuous monitoring of vegetation and importance percentage change in tree layer and subtree layer of D. macropodum. The researching results of D. macropodum distribution, the distribution range of D. macropodum showed expanded more than range of Lim and Oh' result(1999). In other words, it was distributed low density level between Najangsa temple and Byeokryeonam, and distributed in upper Keumsun waterfall and Wonjeok upper valley. D. macropodum was appeared on hiking trails around from Wonjeokam to Bulchulbong. Especially, it was found in this study that D. macropodum was distributed on Seoraebong's north which placed outside area of Naejangsa region. In this study, it was considered that distribution range of D. macropodum was expanded. Also, it is expected to be used as a result of the field study of changing distribution study of broad leaved evergreen forest due to global warming.

• Molecular & Cellular Toxicology
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• v.1 no.1
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• pp.46-51
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• 2005

Mutagen X (MX) exists in our drinking water as the bi-products of chlorine disinfection. Being one of the most potent mutagen, it attracted much attention from many researchers. MX and its analogs are tested and modeled by quantitative structure activity relationship (QSAR) methods. As a result, factors affecting this class of compounds have been found to be steric and electrostatic effects. We tried to collect all the data available from the literature. The quantitative structure-activity relationship of a set of 29 MX was analyzed using Molecular Field Analysis (MFA) and Receptor Surface Analysis (RSA). The best models gave $q^{2}=0.918,\;r^{2}=0.949$ for MFA and $q^{2}=0.893,\;r^{2}=0.954$ for RSA. The models indicate that an electronegative group at C6 position of the furanone ring increases mutagenicity.

• Journal of Korean Academy of Nursing
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• v.21 no.3
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• pp.323-338
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• 1991

This study investigated the effect of supportive nursing care including modified guided imagery on the discomfort, self- esteem, erythrocyte semdimentation rate(ESR) and quality of life(Q. L.) in persons with rheumatoid arthritis (R. A.). The purpose was to contribute to the development of theoretical nursing care to enhance the Q. L. of persons with chronic illness. From Nov. 22, 1990 to May 2, 1991, 49 patients registered at a rheumatic clinic at one general hospital in Seoul, were accepted according to the research criteria as subjects for this study. Among these, 26 were selected for an experimental group to he treated with an interpersonal interview and modified guided imagery, the other 23 became the control group not treated for the purpose of measuring and comparing the effect of the treatment. Statistical analysis was done by a SAS program for X$^2$-test, unpaired t -test, Pearson correlation coefficients and factor analysis. The results were as follows : 1. The pre-experimental discomfort level of the total subject group averaged 25.42(S. D. ＝8.77), and the difference between the pre /post experimental discomfort levels of the two groups was not statistically significant. 2. The pre - experimental self- esteem scores of the total subject group averaged 27.48(S. D. ＝3.95), and the difference between the pre /post experimental self -esteem scores of the two groups was not statistically significant. 3. The pre - experimental Q. L. scores of the total subject group averaged 28.70(S. D. ＝5.99), and the difference between the pre /post experimental Q. L. score of the two groups was statistically significant (t＝2.1748, df＝47, p＝ .0347), 4. The pre - experimental mean of the ESR of the total subject group was 34.48(S. D. ＝19.50) mm, and the difference between the pre /post expeimental ESR scores of the two groups was not statistically significant. 5. The Family support scores of the total subject group averaged 41.28(S. D. ＝10.27). 6. The total subject group 0.L. score was correlated with self-exteem score (r＝ .3984, p＝ .0046). In this study, supportive nursing care including modified guided imagery increased the quality of life scores for this group of persons with R. A. significantly. So the concept of supportive nursing care of this study may be effective in enhancing the quality of life persons with chronic illness. Further investigations related to the methodology and with other groups of clients was recommended.