• Fibers and Polymers
• /
• 제5권3호
• /
• pp.245-251
• /
• 2004

Poly(trimethylene terephthalate-co-trimethylene 2,6-naphthalate)s (P(TT-co-TN)s) with various copolymer composition were synthesized, and their chain structure, thermal property and crystalline structure were investigated by using $^1$H-NMR spectroscopy, differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD), respectively. It was found from sequence analysis that all the P(TT-co-TN) copolymers synthesized have a statistical random distribution of TT and TN units. It was also observed from DSC thermograms that the glass transition temperature increases linearly with increasing the TN comonomer content, whereas the melting temperature of copolymer decreases with increasing the corresponding comonomer content in respective PTT- and PTN-based copolymer, showing pseudo-eutectic melting behavior. All the samples melt-crystallized isothermally except for P(TT-co-66 mol % TN) exhibit multiple melting endotherms and clear X-ray diffraction patterns. The multiple melting behavior originates from the dual lamellar population and/or the melting-recrystallization-remelting. The X-ray diffraction patterns are largely divided into two classes depending on the copolymer composition, i.e., PTT and PTN $\beta$-form diffraction patterns, without exhibiting cocrystallization.

• Korean Journal of Acupuncture
• /
• 제19권2호
• /
• pp.35-39
• /
• 2002

Objective : The purpose of this study was to investigate the Effect of Acupuncture Stimulation of Sohae(H3) and Sobu(H8) Acupoint on Skin Temperature of Sochung Acupint(H9, the end acupoint of Heart Meridian). Sohae and Sobu acupoint has a property of water and fire in the Five agents on Heart Meridian. Methods : Subjects were four healthy oriental medical students volunteers(male, mean age-28). One group(two subjects) received acupuncture on Sohae acupoint(H3) and the other group(two subjects) on Sobu acupoint(H8) while resting. Skin temperature was measured on Sochung acupoint(H9) before, during, and after acupunture stimulation. Each test took 15minutes. The initial 5minutes were definded as BAS(Before Acupuncture Stimulation) period, the following 5minutes as DAS(During Acupuncture Stimulation) period, the last 5minutes as AAS(After Acupuncture Stimulation) period. This test was performed twice in order to increase the statistical authenticity. Results : Our result indicates that acupuncrue stimulation of Sohae acupoint(H3) decreased and Sobu acupoint(H8) increased skin temperature on Sochung acupoint(H9) in the DAS period. The changes remained throughout the AAS period. Our conculusion are that stimulaton of the Water and Fire property-acupoint(H3, H8) on Heart changes the skin temperature on Sochung acupoint on the same Heart Meridian. However this study has no authenticity because it had no regard for many factors effecting on the result and the result of the study was the very reverse of our expectation.

• 디지털융복합연구
• /
• 제18권1호
• /
• pp.11-21
• /
• 2020

본 연구는 경기도를 주요 분석대상으로 하여 공유재산 보유현황, 관리체제와 운영성과, 운영의 한계점 등을 분석하였다. 또한 경기도와 서울특별시, 인천광역시 등의 타 광역단체들의 공유재산 관리체제를 비교·분석하여 시사점을 얻고자 하였다. 동시에 경기도 전체 공유재산 실무담당자를 대상으로 공유재산 운영과 관련된 설문조사를 실시하였다. 분석결과, 경기도는 재정자립도가 완전하지 않기 때문에 재원확충이 중요인데도 불구하고 공유재산의 세외수입 실적이 보유규모에 비해 미미한 수준이다. 그 원인으로는 무엇보다도 공유재산 관리전담부서가 별도로 신설되어 있지 않고 기존의 업무를 담당하는 주무부서도 행정력이 부족하다는 점이 주요 원인이라 판단된다. 따라서 본 연구에서는 공유재산의 운영 성과와 기타 재산 가치를 증대시키기 위해서는 공유재산 전담부서를 신설할 것을 제안하고자 한다. 설문조사에서도 공유재산 운영 성과를 개선시키려면 현재의 관리체제를 개편해야 하며 그 개편방향은 전담부서의 신설이어야 한다는 인식이 형성되어 있음을 확인할 수 있었다.

• 한국항행학회논문지
• /
• 제10권4호
• /
• pp.371-376
• /
• 2006

스피어 디코더의 초기 반지름 결정 문제는 비트 오율 (bit error rate)과 복잡도에 있어서 많은 영향을 미친다. 이런 초기 반지름은 채널의 통계적 특성을 고려함으로 설정되거나, MMSE 결정 값을 이용하여 설정할 수 있다. 채널의 통계적 특성을 이용한 방법은 초기 반지름이 송신 신호에 해당하는 격자점을 매우 높은 확률로 포함한다. MMSE 결정 값을 이용하는 방법은 먼저 수신 신호에서 MMSE 연 판정 부호(soft output information)을 얻은 후, 경 판정(hard decision)을 내린 다음, 수신 신호 공간에서 경 판정 부호에 해당하는 격자점을 찾는다. 그리고 수신 신호와 경 판정 부호에 해당하는 격자점 사이의 유클리디안 거리(Euclidean distance)를 초기 반지름으로 설정한다. 본 논문에서는 채널의 통계적 특성을 이용한 방법에 있어서 기존의 복잡한 수식에 비해 간단한 새로운 식을 유도하고, MMSE 결정값을 이용한 방법과 비교 연구 하였다. 비교를 위해 'Tightness'라는 새로운 측도를 이용하였다. 전산 실험 결과, 낮은 SNR 영역과 중간 정도의 SNR 영역에서는 MMSE를 이용한 방법의 더 많이 디코딩 복잡도 감소를 보였고, 높은 SNR 영역에서는 채널의 통계적 특성을 이용한 방법이 더 낮은 디코딩 복잡도를 보였다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2003년도 봄 학술발표회 논문집
• /
• pp.123-130
• /
• 2003

The estimation of key soil properties and subsequent quantitative assessment of the associated uncertainties has always been an important issue in geotechnical engineering. It is well recognized that soil properties vary spatially as a result of depositional and post-depositional processes. The stochastic nature of spatially varying soil properties can be treated as a random field. A practical statistical approach that can be used to systematically model various sources of uncertainty is presented in the context of reliability analysis of slope stability Newly developed expressions for probabilistic characterization of soil properties incorporate sampling and measurement errors, as well as spatial variability and its reduced variance due to spatial averaging. Reliability analyses of the probability of slope failure using the different statistical representations of soil properties show that the incorporation of spatial correlation and conditional simulation leads to significantly lower probability of failure than obtained using simple random variable approach.

• Communications for Statistical Applications and Methods
• /
• 제10권2호
• /
• pp.535-543
• /
• 2003

A ranked set sample version of the sign test is proposed for testing hypotheses concerning the quantiles of a population characteristic by Kaur, et. al(2002). In this paper, we proposed the ranked set sample Wilcoxon signed rank test for quantiles under equal allocation. We obtain the asymptotic property and the asymptotic relative efficiencies of the proposed test statistic with respect to Wilcoxon signed rank test of simple random sample for quantiles under equal allocation. We calculate the ARE of test statistics, the proposed test statistic is more efficient than simple random sampling for all quantiles. The relative advantage of ranked set sampling is greatest at the median and tapers off in the tails.

• Communications for Statistical Applications and Methods
• /
• 제10권2호
• /
• pp.507-517
• /
• 2003

Self-organizing map (SOM) has been developed mainly by T. Kohonen and his colleagues as a unsupervised learning neural network. Because of its topological ordering property, SOM is known to be very useful in pattern recognition and text information retrieval areas. Recently, data miners use Kohonen´s mapping method frequently in exploratory analyses of large data sets. One problem facing SOM builder is that there exists no sensible criterion for evaluating goodness-of-fit of the map at hand. In this short communication, we propose valid evaluation procedures for the Kohonen SOM of any size. The methods can be used in selecting the best map among several candidates.

• 한국통계학회:학술대회논문집
• /
• 한국통계학회 2000년도 추계학술발표회 논문집
• /
• pp.23-26
• /
• 2000

It is noted that many econometric time series have long-memory properties. A long-memory process, or strongly dependent process, is characterized by hyperbolic decaying autocorrelations and unbounded spectral density at the origin. Since the long-memory property can be observed by data obtained from rather a long period, there is some possibility of parameter change in the process. In this paper, we consider the estimation of change-point when there is a change in the variance of a long-memory process. The estimator is based on some reasonable statistic and the consistency is shown using Taqqu's strong reduction theorem

• Communications for Statistical Applications and Methods
• /
• 제24권3호
• /
• pp.317-324
• /
• 2017

An influence measure known as Cook's distance has been used for judging the influence of each observation on the least squares estimate of the parameter vector. The distance does not reflect the distributional property of the change in the least squares estimator of the regression coefficients due to case deletions: the distribution has a covariance matrix of rank one and thus it has a support set determined by a line in the multidimensional Euclidean space. As a result, the use of Cook's distance may fail to correctly provide information about influential observations, and we study some reasons for the failure. Three illustrative examples will be provided, in which the use of Cook's distance fails to give the right information about influential observations or it provides the right information about the most influential observation. We will seek some reasons for the wrong or right provision of information.

• International Journal of Concrete Structures and Materials
• /
• 제6권4호
• /
• pp.231-237
• /
• 2012

Recently, it has been difficult to get natural sand for concrete due to an insufficient supply in Korea. Crushed sand was thought as a substitute and previous research has been focused on low fluidity and normal compressive strength (24-30 MPa). Study on high performance concrete using crushed sand is hardly found in Korea. In this study it was investigated that the effect of the crushed sand on fluidity and compressive strength properties of high performance concrete. Blending crushed sand (FM: 3.98) produced in Namyangju, Kyunggido and sea sand (FM: 2.80) produced in Asan bay in Chungnam. The final FMs of fine aggregate were 3.50, 3.23, and 3.08. W/B was set as 0.25 to get high performance. With the test results an analysis of relationship was performed using a statistical program. It was shown that strength property of concrete using crushed aggregate at the very early age or after specific time was mainly affected by strength development properties of binders instead of the crushed sand.