• 대한토목학회논문집
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• 제3권3호
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• pp.9-18
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• 1983

본(本) 연구(硏究)는 Sackin, M.J. 와 Merriam, D.F. (1969) 등(等)이 암석(岩石) 및 광물(鑛物)의 구성상태변화(構成狀態變化)를 파악(把握)하기 위해 사용(使用)한 Transition Matrices의 해석방법(解析方法)을 이용(利用)하여 해운대사빈(海雲臺砂濱)의 천이특성(遷移特性)을 파악(把握)할 목적(目的)으로 현장실측자료(現場實測資料)를 토대로 확정(確定)된 천이(遷移)모델의 천이특성(遷移特性)인 특정사빈(特定砂濱)의 출현빈도(出現頻度) 및 그 기여율(寄與率)을 구(求)하였다. 또 실제(實際)의 사빈변화(砂濱變化)가 계절적(季節的)인 순환특성(循環特性)을 보이면서 파랑(波浪)에 응답(應答)하는 시문(時問)과 공간(空間)의 복합적(複合的)인 요소(要素)들을 분리(分離)하여 선형함수(線型函數)의 조합(組合)으로 분석(分析)하고자 Winant, Inmann 그리고 Nordstorm(1975) 등(等)에 의해 제시(提示)된 Empirical Eigenfunction을 해운대사빈(海雲臺砂濱)의 변형해석(變形解析)에 적용(適用)하여 변형원인(變形原因)에 관한 인자(因子)의 규명(糾明)을 시도(試圖)하였으며 분석결과(分析結果) 요지(要旨)는 다음과 같다. (1) 해운대사빈(海雲臺砂濱)의 천이특성파악(遷移特性把握)이 Transition Matrices 전개해석방법(展開解析方法)으로 가능(可能)하였다. (2) 적용(適用)된 경험적(經驗的) 고유함수(固有函數)의 전개결과(展開結果)에 의하여 해운대사빈(海雲臺砂濱) 전체(全體)의 시간(時間) 및 공간적(空間的) 변형(變形)에 대한 설명(說明)이 가능(可能)하였다.

• Journal of electromagnetic engineering and science
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• 제12권1호
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• pp.45-54
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• 2012

When the cylindrical wave is incident on a plane dielectric interface from a denser medium to a rarer one, the asymptotic solution for the transmitted wave in the near region is different from the one in the far region. In this paper, we have derived a novel uniform asymptotic solution represented by using the parabolic cylinder function for the transmitted and scattered waves observed in the rarer medium when the cylindrical wave is incident on the plane dielectric interface from the denser medium. The validity of the uniform asymptotic solution has been confirmed by comparing with the reference solution calculated numerically. It has been clarified that the transition wave plays an important role to connect smoothly the asymptotic solution in the near region to the one in the far region through the transition region. We have shown the very interesting phenomenon that the lateral wave type transmitted wave is observed in the far and shallow region.

• 한국멀티미디어학회논문지
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• 제16권11호
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• pp.1315-1324
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• 2013

This paper mainly focuses on the system quality factors of a website targeted at shopping mall websites in China and Korea. We categorized six system quality factors and formulated hypotheses regarding how those six factors are different. We also conducted an empirical study to verify hypotheses. Statistical data for an empirical study targeted at undergraduate students in Korea and China, having filled in a questionnaire. Reliability of the collected data was measured, and a T-test of the established hypotheses was carried out. The following describes the results that were found. While the shopping mall websites of two countries showed a difference in terms of quick transition of the web pages or images, ease of use, reliability, and accessibility, they did not show the difference in term of accuracy and the short cut function. We analyzed the causes of the verified results and suggested a strategy to implement the effective shopping mall web sites.

• 응용통계연구
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• 제33권1호
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• pp.47-59
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• 2020

본 논문에서는 마코프 이항 회귀 모형의 시차가 알려져 있거나 그렇지 않은 경우일 때, t-링크 함수를 갖는 종단적 마코프 이항 회귀 모형을 제시한다. 일반적으로, 이항 회귀 모형에서는 로직 모형이나 프로빗 모형이 주로 사용된다. t-링크 함수는 t 분포가 자유도가 커질수록 정규분포로 근사하기 때문에 프로빗 모형을 대신 더 많은 유연성을 위해 사용될 수 있다. 게다가 마코프 회귀모형은 종단 자료에 대해 사용될 수 있다. 우리는 마코프 회귀 모형의 시차를 결정하기 위해 베이지안 방법을 제시하고자 한다. 특히, 각 모델의 차수에 대해 알고 있는 경우에는 DIC를 기준으로 모델 비교를 실시하였다. 모델의 차수에 대해 모르는 경우에는 가능한 모델들의 사후 확률을 이용하였다. 복잡한 베이지안 계산을 해결하기 위하여 Albert와 Chib (1993), Kuo와 Mallick (1998)과 Erkanli 등 (2001)의 방법을 이용하여 모델을 재설정하였다. 제안하는 방법은 시뮬레이션 데이터와 Somer 등 (1984)에 의해 조사된 인도네시아 어린이 종단 데이터에 적용했다. 마코프 이항 회귀모형의 순서에 대해서 아는 경우와 모르는 경우를 각각 가정하여 최적의 모델을 알아보기 위해 MCMC 방법을 사용하였다. 또한, 매트로폴리스 해스팅 알고리즘의 수렴성을 점검하기 위해 Gelman과 Rubin의 진단을 이용했다.

• Fibers and Polymers
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• 제2권2호
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• pp.98-107
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• 2001

The phase transition behavior isothermal micro-phase separation kinetics of polyester-based thermoplastic elastomer were studied using the synchrotron X-ray scattering(SAXS) method. The structural changes occurring during heating period were investigated by determining the changes of the one-dimensional correlation function, interfacial thickness and Porod constant. Based on the abrupt increases of the domain spacing and interfacial thickness, a major structural change occurring well below the melting transition temperature is suggested. Those changes are explained in terms of melting of the thermodynamically unstable hard domains or/and the interdiffusion of the hard and soft segments in the interfacial regions. SAXS profile changes during the micro-phase separation process were also clearly observed at various temperatures and the separation rate was found to be sensitively affected by the temperature. The peak position of maximum scattering intensity stayed constant during the entire course of the phase separation process. The scattering data during the isothermal phase separation process was interpreted with the Cahn-Hilliard diffusion equation. The experimental data obtained during the early stage of the phase separation seems to satisfy the Cahn-Hilliard spinodal mechanism. The transition temperature obtained from the extrapolation of the diffusion coefficient to zero value turned out to be about 147$\pm$$2^{\circ}$, which is close to the order-disorder transition temperature obtained from the Porod analysis. The transition temperature was also estimated from the inveriant growth rate. By extrapolating the inveriant growth rate to zero, a transition temperature of about 145$\pm$$\pm$$2^{\circ}$ was obtained.

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3595-3600
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• 2014

Monitoring of pH, especially under highly alkaline conditions, is necessary in various processes in the industrial, biotechnological, agricultural, and environmental fields. However, few pH indicators that can function at highly alkaline levels are available, and most of which are organic-based pH indicators. Several years ago, it was reported that gold nanoparticles prepared using trisodium citrate dihydrate were rapidly aggregated at pH values higher than ~12.7. A shift of surface plasmon resonance for such aggregated gold nanoparticles can be applied to pH indicators, allowing for the substitution of traditional organic-based pH indicators. The most important characteristic of pH indicators is the transition pH range. Herein, gold and silver nanoparticles are prepared using different reducing agents, and their transition pH ranges are examined. The results showed that all nanoparticles prepared in this study exhibit similar transition pH ranges spanning 11.9-13.0, regardless of the nanoparticle material, reducing agents, and concentration.

• 세라미스트
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• 제23권1호
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• pp.101-109
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• 2020

In this study, the phase transition behaviors of lead-free (Na_1/2Bi_1/2TiO₃)_(1-x)-(BaTiO₃)_x (NBT-BT) are investigated by using Brillouin spectroscopy. The elastic properties, sound velocity and absorption coefficient of NBT-BT are characterized as a function of temperature along different crystallographic axes. The temperature dependences of the elastic constants of NBT-BT near the morphotropic phase boundary are determined for the first time. The unpoled NBT-BT single crystals exhibits the typical relaxor behaviors, presenting broad acoustic and dielectric anomalies. The application of electric field induced discontinuous changes in the elastic properties at ~110℃, which indicates field-induced phase transition occurred. The electric field also changes the dielectric constant from more relaxor-like to ferroelectric-like dielectric behavior.

• Bulletin of the Korean Chemical Society
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• 제18권10호
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• pp.1105-1108
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• 1997

The new amorphous intermetallic compounds, M3(AsTe3)2: M=Cr, Co, Fe, were synthesized by the precipitation reaction of the Zintl anion AsTe33- with the divalent transition metal halides in aqueous solution and analyzed by EDS equipped with SEM and PIXE. The empirical formula of the specimens was found to be Fe3.0As1.8Te5.9, Co3.0As2.1Te6.5, and Cr3.0As2.0Te6.9 by the quantitative elemental analysis. The dc specific resistivity of the materials was measured as a function of temperature in the range from 20 to 300 K, in which their resistivity of Cr3(AsTe3)2 was largely dependent on temperature, while those of Co3(AsTe3)2 and Fe3(AsTe3)2 were only slightly dependent on temperature. To characterize the spin glass state of the specimens, the ac and dc magnetic susceptibility were measured and it was found that Co3(AsTe3)2 and Fe3(AsTe3)2 undergo a transition to a spin glass state at 6 K and 38 K, respectively. Magnetization data are reported as both thermal remanent magnetization (TRM) and isothermal remanent magnetization (IRM) as a function of magnetizing field and temperature.

• Macromolecular Research
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• 제16권6호
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• pp.539-543
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• 2008

Many natural proteins self-assemble in complex ways, either to fulfill their biological function or introduce particular properties, such as high strength and toughness. We report the morphological transition in water from a spherical to rod-like shape of Bombyx mori silk fibroin by reducing the pH. Transmission electron microscopy, scanning electron microscopy, and dynamic light scattering were used to characterize the dilute solutions of silk fibroin in an aqueous environment, and provide direct visualization of the transformation of spherical micelles at pH 6.8 to nanofibrils at pH 4.8. This change in morphology occurred as a result of the stretching entropy due to the formation of $\beta$-sheets, which was analyzed using circular dichroism spectroscopy. This study demonstrates the self-assembly of silk fibroin as a function of pH.

• Macromolecular Research
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• 제10권6호
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• pp.311-317
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• 2002

The quantitative analysis of polymer micelles consisting of amphiphilic block copolymers was carried out by small-angle neutron scattering (SANS). The block copolymers, made of poly(2-ethoxyethyl vinyl ether-b-2-hydroxyethyl vinyl ether)(poly(EOVE-b-HOVE)), exhibited a sharp morphological transition from a homogeneous solution to a micelle structure with increasing temperature. This transition is accompanied by a formation of spherical domains of poly(EOVE) with a radius around 200 $\AA$. The variations of the size and its distribution of the domains were investigated as a function of polymer concentration and temperature. The validity of SANS analysis, including the wavelength- and incident-beam-smearing effects of the SANS instrument, was examined with a pre-calibrated polystyrene latex.