• ETRI Journal
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• 제36권1호
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• pp.155-158
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• 2014

This letter presents an antenna design method for an orthogonally-polarized dual antenna for use in mobile stations (MSs) and includes a verification method for improving the link-level throughput performance of an MS that uses a proposed multiple-input multiple-output antenna. The link-level throughput performance of an MS is strongly related to the correlation between antenna branches, which is determined by the cross polarization discrimination of the second branch antenna, both numerically and experimentally.

• Journal of information and communication convergence engineering
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• 제1권1호
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• pp.1-5
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• 2003

This paper discusses the spectral efficiency and performance of asynchronous direct sequency spread spectrum multiple access systems strict bandwidth limitation by Nyquist filtering. The signal to noise plus interference ratio(SNIR) at the output from the correlation receiver is derived analytically taking the cross correlation characteristics of spreading sequences into account, and also an approximated SNIR of a simple form is presented for the systems employing Gold sequences. Based on the analyzed result of SNIR, bit error rate performance and spectral efficiency are also estimated. and at last, we analyzed improvement rate using RS, convolution as a method for improving functions.

• 한국전산유체공학회지
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• 제4권1호
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• pp.27-33
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• 1999

Spiral tube heat exchangers can find numerous applications in many engineering fields. Flow in spiral tubes is interest to engineers due to occurrence of secondary flow which enhances the cross-sectional mixing and the heat transfer rate. In the present study, an incompressible viscous 3-D flow in spiral tubes with rectangular cross-section of various torsion rate and Reynolds number is studied by using a finite volume method. It is shown that the axial velocity profile is affected by the secondary flow motion. Because there is some difference from correlation proposed by Hur et al., a lot of analysis and arrangement of experimental results are needed. This study showed the results of variation of hydrodynamic entry length for torsion and Re numbers.

• 환경영향평가
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• 제28권2호
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• pp.83-100
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• 2019

본 연구는 팔당호 내 4개 지점을 대상으로 각 지점에서의 장기 수질 변화 및 지점 간 시차성을 확인하기 위하여 비모수적 추세분석 방법인 Seasonal Kendall test, LOWESS와 Cross Correlation을 수행하였다. 본 분석을 위하여 2004년 1월부터 2016년 12월까지, 각 지점별 9개 수질 항목(수온, EC, DO, BOD, COD, T-N, T-P, TOC, Chl-a)의 주별 분석 자료를 사용하였다. Seasonal Kendall test 결과 수온은 증가, EC와 T-N, T-P는 전 지점 모두 감소 경향을 나타내었다. LOWESS 결과 BOD 농도는 전 지점에서 2013년부터 2016년까지 "감소" 경향을 나타내었고 COD는 2012년부터 "증가" 경향을 나타내었다. 따라서 2012~2013년은 팔당호 전 지점에서 BOD의 개선과 함께 COD의 증가가 나타나는 전환기였음을 확인할 수 있었다. Cross Correlation 결과, 모두 시차성 없음으로 나타났다. 본 연구를 통하여 팔당호에 대한 보다 적합한 수질관리를 위하여 위의 전환기에 대한 발생원인 분석과 함께 수질 측정주기의 증가를 통한 보다 정밀한 모니터링이 필요할 것으로 판단된다.

• 대한원격탐사학회지
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• 제34권6_1호
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• pp.1143-1153
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• 2018

TOPS InSAR 처리를 위해서는 고정밀도의 영상정합이 요구된다. Sentinel-1 TOPS 모드영상에 교차상관 영상정합, 기하정합, Spectral Diversity 정합에 기반 한 Enhanced Spectral Diversity 정합 알고리즘 성능 비교분석을 통해 TOPS모드에 적합한 영상정합 방법을 제시하고자 한다. 25개의 Sentinel-1 TOPS 영상으로부터 생성된 23개의 간섭쌍을 이용하여, 교차상관정합(CC), 기하보정(GC1), 기하보정 후 교차상관정합(GC2, GC3, GC4) 그리고 ESD를 이용한 정합(ESD_GC, ESD_1, ESD_2) 총 8가지 방법을 적용하였다. 교차상관정합과 기하정합에 따른 azimuth 방향 정합오차를 평균한 결과는 각각 0.0041 화소, 0.0016 화소이다. 비록 ESD 방법은 azimuth 정합오차가 0.0005 화소 이하로 가장 정확한 결과를 보이지만, 기하정합 결과는 추가적인 교차상관정합을 통한 반복 과정을 통해 0.001 화소 정도로 오차가 감소하였다. ESD 방법은 burst 중첩지역의 긴밀도가 낮은 경우 적용이 불가능하다. 따라서 반복 적용을 통한 기하정합 방법은 다수의 SAR 자료를 이용한 시계열 분석 또는 긴 시간간격을 갖는 간섭도 생성을 위해서 적합한 대안이 된다.

• 한국전자통신학회논문지
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• 제7권2호
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• pp.263-269
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• 2012

CDMA는 여러 사용자가 시간과 주파수를 공유하면서 각 사용자에게 확산코드라고 하는 서로 다른 의사잡음수열(pseudonoise sequence)을 할당한다. 각 사용자는 할당된 확산코드를 이용하여 송신할 신호를 변조한다. 신호를 변조하는데 사용하는 코드를 선택하는 것은 CDMA 시스템의 수행능력을 결정하는 데 있어 매우 중요하다. 왜냐하면 품질이 좋은 수열은 사용자들 사이의 신호들의 간섭을 줄이고 신호를 잘 복호할 수 있도록 하기 때문이다. 수신자는 데이터를 복호하기 위해 수신된 부호를 동기화한다. 서로 독립인 코드를 사용하는 것은 동시 다중접속을 가능하게 한다. 본 논문에서는 확산 스펙트럼 통신에서 다중접속 충돌을 최소화하고, 시스템의 보안을 증가시키고 사용자의 수를 늘이는데 도움을 주는 비선형 수열을 생성하고 상호상관관계를 분석한다.

• The Korean Journal of Pain
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• 제34권4호
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• pp.501-508
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• 2021

Background: Yellow flags are psychosocial factors shown to be indicative of long-term chronicity and disability. The purpose of the study was to evaluate the psychometric properties of the Turkish Yellow Flag Questionnaire (YFQ) in patients with chronic musculoskeletal pain (CMP). Methods: The cross-cultural adaptation was conducted with translation and back-translation of the original version. Reliability (internal consistency and test-retest) was examined for 231 patients with CMP. Construct validity was assessed by correlating the YFQ with the Hospital Anxiety and Depression Scale (HADS), Orebro Musculoskeletal Pain Questionnaire (OMPQ), and Tampa Kinesiophobia Scale (TKS). Factorial validity was examined with both exploratory and confirmatory factorial analysis. Results: The YFQ showed excellent test/retest reliability with an Intraclass correlation coefficient of 0.82. The internal consistency was moderate (Cronbach's alpha of 0.797). As a result of the exploratory factor analysis, there were 7 domains compatible with the original version. As a result of confirmatory factor analysis, the seven-factor structure of YFQ was confirmed. There was a statistically significant correlation between YFQ-total score and OMPQ (r = 0.57, P < 0.001), HADS-anxiety (r = 0.32, P < 0.001), HADS-depression (r = 0.44, P < 0.001), and TKS (r = 0.37, P < 0.001). Conclusions: This study's results provide considerable evidence that the Turkish version of the YFQ has appropriate psychometric properties, including test-retest reliability, internal consistency, construct validity and factorial validity. It can be used for evaluating psychosocial impact in patients with CMP.

• Journal of Korean Neurosurgical Society
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• 제59권3호
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• pp.276-281
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• 2016

Objective : Although trunk muscles in the lumbar spine preserve spinal stability and motility, little is known about the relationship between trunk muscles and spinal fusion rate. The aim of the present study is to evaluate the correlation between trunk muscles cross sectional area (MCSA) and fusion rate after posterior lumbar interbody fusion (PLIF) using stand-alone cages. Methods : A total of 89 adult patients with degenerative lumbar disease who were performed PLIF using stand-alone cages at L4-5 were included in this study. The cross-sectional area of the psoas major (PS), erector spinae (ES), and multifidus (MF) muscles were quantitatively evaluated by preoperative lumbar magnetic resonance imaging at the L3-4, L4-5, and L5-S1 segments, and bone union was evaluated by dynamic lumbar X-rays. Results : Of the 89 patients, 68 had bone union and 21 did not. The MCSAs at all segments in both groups were significantly different (p<0.05) for the PS muscle, those at L3-4 and L4-5 segments between groups were significantly different (p=0.048, 0.021) for the ES and MF muscles. In the multivariate analysis, differences in the PS MCSA at the L4-5 and L5-S1 segments remained significant (p=0.048, 0.043 and odds ratio=1.098, 1.169). In comparison analysis between male and female patients, most MCSAs of male patients were larger than female's. Fusion rates of male patients (80.7%) were higher than female's (68.8%), too. Conclusion : For PLIF surgery, PS muscle function appears to be an important factor for bone union and preventing back muscle injury is essential for better fusion rate.

• 지역사회간호학회지
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• 제23권1호
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• pp.1-12
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• 2012

Purpose: This study carried out a preliminary analysis of available literature and used the ecological approach to define a research hypothesis with focus on individual, family, and school variables related to early adolescents' urge to run away. This study also aimed to examine the influence of each of these variables in order to build a forecast model showing which variables have more influential on early adolescents' urge to run away. Methods: Materials were collected from 433 male and female fifth- and sixth-grade students at two schools in Gyeonggi Province. Analysis was carried out using SPSS/WIN 18.0. Frequency analysis, ${\chi}^2$-test, t-test, correlation analysis and logistic regression analysis were conducted. Results: The results indicate that personal factors related to runaway impulse are gender and previous runaway attempts, family-related factor family functionality, and school-related factor the area of stress from study. Conclusion: Based on the study results as above, individual, family, and school interventions need to be developed.

• 한국도로학회논문집
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• 제12권2호
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• pp.123-127
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• 2010

본 논문에서는 최소단면 보수가 완료된 아스팔트 콘크리트 포장의 평탄성 평가를 위하여 경량 프로파일러를 이용하여 측정하였으며 평탄성 분석을 실시하였다. 측정 프로파일러의 정확도를 검토하기 위하여 2회 측정한 프로파일을 이용하여 반복성(repeatability) 검증을 수행하였다. Cross-Corelation 함수를 이용하여 측정치간의 일치를 검증하였다. 최소단면 보수가 이루어진 아스팔트 콘크리트 포장 부분과 기존 포장의 평탄성을 국제평탄성지수와 PrI 지수를 비교 분석하였으며, 최소단면 보수가 이루어진 차선의 평탄성이 대체적으로 좋지 않았다. 향후 최소단면 보수 지역의 평탄성 평가에 대한 기초자료로 사용할 수 있다고 판단된다.