• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.6
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• pp.633-641
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• 2020

Residential complexes offer a sense of community and convenience, but making closed and privated space have been criticized.Closed urban spaces have issues encouraging residential segregation.large apartment complexes over 1,000 households,the most poular housing type in Korea, seems to make urban space more closed and privated than ever before. Our study puts forward and tests the hypothesis that large apartment complexes with over 1,000 households are linked to residential segregation. First of all, we examined the degree of residential segregation of metropolitan cities in Korea over a nine-year period (2011-2019). The dissimilarity index and the delta index were used for determining the extent of residential segregation. Next, we tested our hypothesis by Spearman's rank correlation analysis. Spearman's rank correlation analysis was performed on the residential segregation index per administrative division ("dong") and the number of large apartment complexes per administrative division ("dong").

• The Journal of Korean Institute of Communications and Information Sciences
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• v.8 no.3
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• pp.113-119
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• 1983

In this paper, a method of the step size adaption is studied on the delta modulation coding of speech signals. Exponential adaption processes are reserched by a new circuit model. It is presented a shorten error recovery in decoder step size. Practical considerations favor one algorithm, and its digital implementation has been adapted for the illustration of above method, using the rate multipliers and the validity is verified by laboratory experiment.

• Sleep Medicine and Psychophysiology
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• v.9 no.1
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• pp.24-33
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• 2002

Objectives: Nasal continuous positive airway pressure (CPAP) corrected elevated blood pressure (BP) in some studies of obstructive sleep apnea syndrome (OSAS) but not in others. Such inconsistent results in previous studies might be due to differences in factors influencing the effects of CPAP on BP. The factors referred to include BP monitoring techniques, the characteristics of subjects, and method of CPAP application. Therefore, we evaluated the effects of one night CPAP application on BP and heart rate (HR) reactivity using non-invasive beat-to-beat BP measurement in normotensive and hypertensive subjects with OSAS. Methods: Finger arterial BP and oxygen saturation monitoring with nocturnal polysomnography were performed on 10 OSAS patients (mean age $52.2{\pm}12.4\;years$; 9 males, 1 female; respiratory disturbance index (RDI)>5) for one baseline night and another CPAP night. Beat-to-beat measurement of BP and HR was done with finger arterial BP monitor ($Finapres^{(R)}$) and mean arterial oxygen saturation ($SaO_2$) was also measured at 2-second intervals for both nights. We compared the mean values of cardiovascular and respiratory variables between baseline and CPAP nights using Wilcoxon signed ranks test. Delta ($\Delta$) BP, defined as the subtracted value of CPAP night BP from baseline night BP, was correlated with age, body mass index (BMI), baseline night values of BP, BP variability, HR, HR variability, mean $SaO_2$ and respiratory disturbance index (RDI), and CPAP night values of TWT% (total wake time%) and CPAP pressure, using Spearman's correlation. Results: 1) Although increase of mean $SaO_2$ (p<.01) and decrease of RDI (p<.01) were observed on the CPAP night, there were no significant differences in other variables between two nights. 2) However, delta BP tended to increase or decease depending on BP values of the baseline night and age. Delta systolic BP and baseline systolic BP showed a significant positive correlation (p<.01), but delta diastolic BP and baseline diastolic BP did not show a significant correlation except for a positive correlation in wake stage (p<.01). Delta diastolic BP and age showed a significant negative correlation (p<.05) during all stages except for REM stage, but delta systolic BP and age did not. 3) Delta systolic and diastolic BPs did not significantly correlate with other factors, such as BMI, baseline night values of BP variability, HR, HR variability, mean SaO2 and RDI, and CPAP night values of TWT% and CPAP pressure, except for a positive correlation of delta diastolic pressure and TWT% of CPAP night (p<.01). Conclusions: We observed that systolic BP and diastolic BP tended to decrease, increase or remain still in accordance with the systolic BP level of baseline night and aging. We suggest that BP reactivity by CPAP be dealt with as a complex phenomenon rather than a simple undifferentiated BP decrease.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.756-763
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• 2005

본 논문에서는 KOSPI200 지수선물의 분 단위 가격 데이터를 이용하여 거래비용을 고려한 옵션 복제 전략들의 성과를 비교하였다. 비교를 위해 사용한 옵션 복제 전략들은 (1)Black-Scholes 델타(delta) 전략, (2)Black-Scholes 델타 한도 전략, (3)Leland 전략, (4)Whalley-Wilmott 전략이다. 각 전략들은 옵션 복제를 위한 기초자산 거래와 관련된 두 가지 질문에 대한 답을 준다. 첫 번째 질문은 거래 시점에 관한 것으로, '언제 거래할 것인가'이고, 두 번째 질문은 거래량에 관한 것으로, '얼마만큼 거래할 것인가'이다. 본 논문에서는 현실적인 KOSPI200 지수선물 거래수수료(거래금액 대비 0.01%) 환경에서 잔존만기 1년인 유럽형 등가격 콜 옵션을 복제하는 경우를 실험하였다. 실험 결과 Leland 전략을 제외한 나머지 세 전략들의 복제 성과가 상대적으로 뛰어난 것으로 나타났다. 그러나 이들 세 전략들 간에는 복제 성과에 대해 뚜렷한 차이를 발견하기 어려웠다. 한편, 복제 종료 시점에서의 복제 손익에 큰 영향을 미치는 요인은 복제 오차(복제 포트폴리오의 만기 가치와 복제 대상 옵션의 만기 현금흐름의 차이)인 것으로 나타난 반면, 복제를 위한 기초자산 거래비용이 복제 종료 시점에서의 복제 손익에 미치는 영향은 적은 것으로 나타났다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.9 no.3
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• pp.120-126
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• 1984

In this paper, there is presented the novel encoder circuit design method in the realization of exponential adaption process on the delta modulation coding of speech signals. The digital implementation has been adapted for the illustration of above, especially using a rate multiplier end a double integration circuit. The use of a double integration of the local decoder included in the ADM encoder in prove the undesirable characteristics which the low switching speed of the ratemultiplier couses the SQNR to decreuse, and the SQNR of the decoding signal by above realization is relatively uniformed in wide range of signal levels. The validity of the above design is verified by laboratory experiments.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.699-710
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• 2014

Government enacted "The special Law on the waterfront-space" to conduct four-river refurbishment project and to construct systematically regions around national rivers from 2009. This law allows public apartments and recreational facilities etc. to be located around four-river, then the law may give rise to serious space change and landscape damage. So we draw some problems of the established development project about the riverside area, and expected a space and landscape change of waterfront-space with a 3D simulation. The result, it is important to adjust the development density of site and apply various contents with take the regional characteristics into consideration for sustainable development.

• Sleep Medicine and Psychophysiology
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• v.5 no.1
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• pp.103-110
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• 1998

Objectives : High co-morbidity of periodic limb movements during sleep(PLMS) and obstructive sleep apnea syndrome(OSAS) is well known and their incidences tend to increase in the elderly. Previous studies have inconsistently rep0l1ed increase or no change of periodic limb movement index(PLMI) by nasal continuous positive airway pressure(CPAP) in OSAS without analyzing possible variables affecting PLMI. We attempted to examine PLMI change evoked during CPAP titration and also factors affecting it in OSAS. Methods : Twenty-nine OSAS patients(M:F=26:3, mean age: $51.6{\pm}10.6\;yrs$) without other sleep disorders except for PLMS were selected, based on the nocturnal (baseline) polysomnograhy. Another night of noctumal polysomnography was performed for CPAP pressure titration. We compared between those two nights PLMI, mean and lowest $SaO_2$, and sleep variables. We also calculated PLMI differences between baseline and CPAP nights, named as delta PLMI (value of CPAP night PLMI minus value of baseline night PLMI). Correlations were calculated between delta PLMI and factors such as age, body mass index, applied CPAP pressure, baseline night values of respiratory disturbance index, mean and lowest $SaO_2$, and sleep parameter differences between baseline and CPAP nights. Results : Decrease of RDI(p<.01) and increase in mean and lowest $SaO_2$ (p<.05, p<.01) were observed during CPAP night. No sleep parameters showed significant change except for the decrease of total stage 1 sleep%(p<.01) during CPAP night. Ten out of 29 patients showed PLMI increase, while the other 19 patients showed either no change(n=14) or even PLMI decrease(n=5) during CPAP night. The 10 patients showing PLMI increase during CPAP night showed a significant positive correlation between delta PLMI and baseline night RDI(p<.05), which meant that PLMI increase was found to be more prominent in higher RDI patients than in lower RDI ones. There were no significant correlations between delta PLMI and other factors in the other 19 patients. Conclusions : We suggest that during the baseline night PLMS would have been underscored and/or masked due to the overlapping of PLMS and apneas/hypopneas or the arousals induced by apneas/hypopneas. Despite its still unknown mechanism, the CPAP application may unmask PLMS and increase PLMI in a subgroup of OSAS patients. It needs to be evaluated further whether the chronic CPAP use sustains the above finding.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.24-32
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• 2017

In this paper, a low power 4th order delta-sigma modulator was designed with a high resolution of 12 bits or more for the biological signal processing. Using time-interleaving technique, 4th order delta-sigma modulator was designed with one operational amplifier. So power consumption can be reduced to 1/4 than a conventional structure. To operate stably in the big difference between the two capacitor for kT/C noise and chip size, the variable-stage amplifier was designed. In the first phase and second phase, the operational amplifier is operating in a 2-stage. In the third and fourth phase, the operational amplifier is operating in a 1-stage. This was significantly improved the stability of the modulator because the phase margin exists within 60~90deg. The proposed delta-sigma modulator is designed in a standard $0.18{\mu}m$ CMOS n-well 1 poly 6 Metal technology and dissipates the power of $354{\mu}W$ with supply voltage of 1.8V. The ENOB of 11.8bit and SNDR of 72.8dB at 250Hz input frequency and 256kHz sampling frequency. From measurement results FOM1 is calculated to 49.6pJ/step and FOM2 is calculated to 154.5dB.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.462-470
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• 2015

This study examined for which socio-economic difference effects on brain function and Problem behavior syndrome in children. About a children with no disorders, diseases or cognitive dysfunction-30 were from LIC children and another 30, from MC ones, the study was conducted by measuring and analyzing the data using brain function analysis and K-CBCL from January to April, 2013. The results of the study are as follows. First, it was found that the ratio of LIC's theta(${\Theta}$) and SMR waves and that of delta(${\delta}$), high beta(${\beta}h$), alpha(${\alpha}$) and low beta(${\beta}l$) waves showed significantly higher values than MC children. Second, concerning the symptoms of child behavioral problems, LIC showed significantly higher values than MC children in symptoms of the body, depression and anxiety, social immaturity, thinking problems, attention problems, aggression, internalization, externalization, overall behavioral problems, and emotional instability. MC children showed significantly higher values than LIC chidren in symptoms of social, academic-performance, total social skills. In conclusion, the significant difference of the brain functions and the symptoms of child behavioral problems between LIC and MC children showed that the socio-ecnomic difference has an influence on the same functions and symptoms above.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.4 s.70
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• pp.427-434
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• 2005

In this study, to develop composite bridge deck of many advantages such as light weight, high strength, corrosion resistance and high durability, profile design, laminate design and finite element analysis were carried out. In the analysis, 5-girder single span bridge with composite deck was considered. Deflection serviceability, failure criteria and web buckling were evaluated. Composite deck of designed profile was fabricated with pultrusion process. The coupon tests were conducted for the fabricated deck and the results were described.