• The Korean Journal of Rheology
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• v.3 no.2
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• pp.148-155
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• 1991

본 연구에서는 빗모양이 고분자분자가 희석용액상태에 있을때의 점탄성 거동을 이 론적으로 해석하였다. 수치해석 방법으로는 Osaki 등이 제안한 방법을 따랐다. 고분자분자 의 이완시간은 Eigenvalue equation을 풀어서 구하였으며 고분자분자와 용매간의 역학은 Zimm-Kilb model을 적용하였다. 본 연구에서는 분지쇄의 길이가 다른 경우 이들이 분자쇄 거동에 미치는 영향을 고찰하였으며 높은 진동수에서의 현상을 해석하였다.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.08a
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• pp.201-208
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• 1998

구음마비환자의 특징적 문제로는 조음 명료성의 저하오 kdns율의 장애등이 논의되어왔다. 지금까지 조음 명료성을 진단하고 치료하기 위한 연구는 활발히 진행되어 왔으나 운율 장애를 측정, 치료하기 위한 연구는 극히 소수이며 특히, 우리나라의 경우는 전무한 상태이다. 이에 본 연구자는 정상군과 이완성 구음마비환자군의 운율적 차이를 음폭, 음도차, 지속시간, 강도의 측면에서 기술하여 진단과 치료를 위한 기초 자료를 제시하고자 한다. 실험 대상은 이완성 구음마비환자군 6명과 정상군 6명이다. 정상군은 환자군과 성별, 나이, 학력, 방언을 맞추어 선정한다. 본 연구는 억양 대비가 분명히 나타나는 의문형 어미와 서술형 어미를 선택한다. 예문은 억양 곡선을 잘 나타내기 위해 유성 자음과 모음으로 구성된 것으로 한다. 종결형 어미가 분석 목표이나 예문의 길이가 너무 짧은 경우 경도환자의 특징이 잘 나타나지 않을 수 있으므로, 주어+목적어+서술어로 구성된 3어절로 구성된 예문을 사용한다.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.26-27
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• 2000

층 성장 방향으로 정전기장을 걸어준 GaAs/AlGaAs 초격자 반도체에서, 두 개의 100 fs 광학 펄스에 의해 생성된 four-wave-mixing(FWM) 신호의 dephasing 현상을 반도체 블록 방정식을 사용해서 분석하고자 한다. 이 FWM 신호의 이완은 전하-전하와 전하-포논 충돌과 같은 phase-breaking 충돌 과정들에 의해서 야기되는 비선형적인 광분극의 dephasing에 의해서 결정되어 진다.$^{(1)}$ 이 비선형적인 광분극은 펄스들에 의해서 동시에 여기되어 나타나는 자유전하 분극과 엑시톤 분극으로 구성되는데, 이 두 분극의 이완시간 특성은 서로 다른 거동을 보인다.$^{(2,3)}$ GaAs/AlGaAs 초격자 반도체에서 이 자유 전하 분극의 dephasing이 엑시톤 분극의 dephasing 보다 훨씬 빠르게 일어나고, 엑시톤이 자유 전하의 특성을 갖게 될수록, 즉 온도가 높을수록 또 엑시톤이 3차원의 특성을 가질수록 이 dephasing은 빠르게 일어난다.$^{(4)}$ (중략)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.2930-2936
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• 2014

The purposes of this study were to investigate the characteristics of speech rate and pause in patients with flaccid dysarthria. For this purpose, 15 patients with flaccid dysarthria and 15 normal speakers matched in gender and age participated as subjects. The overall speech rate, the articulation rate, the inter-sentence and the intra-sentence pause duration and pause frequency were measured during reading the standardized passage "Autumn"(Kim, 1996). As a result, the overall speech rate and articulation rate of patients with flaccid dysarthria were significantly slower than normal speakers and intra-sentence pause duration and frequency of patients with flaccid dysarthria were significantly higher than normal speakers, but those of inter-sentence weren't. The results from this study provides the speech rate index of flaccid dysarthria and indicates that to control the speech rate of flaccid dysarthria have regard to not only the overall speech rate and the articulation rate but also the intra-sentence pause duration and the frequency.

• Investigative Magnetic Resonance Imaging
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• v.10 no.1
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• pp.20-25
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• 2006

Purpose : To evaluate the NMR relaxation properties of newly developed high performance paramagnetic complexes. Materials and methods : 4-aminomethylcyclohexane carboxylic acid (0.63g, 4 mmol) was mixed with the suspension solution of DMF (15mL) and DTPA-bis-anhydride (0.71g, 2 mmol) to synthesize the ligand. The ligand was then mixed with Gd2O3 (0.18g, 0.5 mmol) to synthesize Gd-chelate. For the measurement of magnetic relaxivity of paramagnetic compounds, the compounds were diluted to 1mM and then the relaxation times were measured at 1.5T(64 MHz). Inversion-recovery pulse sequence was employed for T1 relaxation measurement and CPMG(Carr-Purcell-Meiboon-Gill) pulse sequence was employed for T2 relaxation measurement. Using MATLAB(Version 7.1) program, T1 magnetic relaxation map, R1 map, T2 magnetic relaxation map and R2 map were developed to represent magnetic relaxation time and magnetic relaxivity as image. Results : Compared to $R1=4.9mM^{-1}sec^{-1}$ and $R2=4.8mM^{-1}sec^{-1}$ of Omniscan (Gadodiamide), which is commercially available paramagnetic MR agent, R1 of SUK090(Gd-C32H74N5O24) was $12.46mM^{-1}sec^{-1}$ and R1 of SUK091(Gd-C34H78N5O24) was $12.77mM^{-1}sec^{-1}$. However, R1 of SUK092(Gd-C30H56N5O17) was decreased to $2.09mM^{-1}sec^{-1}$. In case of R2, SUK090(Gd-C32H74N5O24) was $8.76mM^{-1}sec^{-1}$ and SUK091(Gd-C34H78N5O24) was $7.60mM^{-}1sec^{-1}$ whereas SUK092(Gd-C30H56N5O17) was decreased to $1.82mM^{-1}sec^{-1}$. Conclusion : Among three new paramagnetic complexes, SUK090(Gd-C32H74N5O24) and SUK091(Gd-C34H78N5O24) showed higher T1, T2 magnetic relaxation rates than that of commercially available paramagnetic MR agent and thus expected to have more contrast enhancement effect.

• Journal of the Korean Chemical Society
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• v.39 no.8
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• pp.604-610
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• 1995

The interaction between 3,3'-dipropyl oxacarbocyanine and poly(styrenesulfonate) has been studied by means of absorption and fluorescence spectroscopic methods. The results was interpreted by stacking model. The kinetic studies of the interaction between 3,3'-dipropyl oxacarbocyanine and poly(styrenesulfonate) were carried out by the absorption and fluorescence spectroscopic stopped-flow methods. The observed relaxation effect in DPC-PSS system was described quantitatively by assuming two relaxation processes. The dependence of rate of reaction on the salt concentration of the solution was also studied. The results are consistent with the two-step mechanism.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.33-43
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• 2016

In order to analyze ground relaxation and cavity formation mechanism due to deteriorated sewer pipe, field test was carried out and a numerical assessments were compared with the field test results. An artificial underground cavity was intended using the ice block overlaying the buried pipe and confirmed that the cavity and relaxation of the surrounding ground were gradually formed as the ice block starts to melt down. Such mechanism was highly suspected to be involved with soil particle interlocking as a soil compaction was a typical process for the buried pipes. In exploring such mechanism numerically, commercially available DEM (Discrete Element Method) code PFC2D was used and the interlocking induced cavern behaviors were successfully simulated and compared with field test results by utilizing the clump logic imbedded in PFC code.

• Journal of radiological science and technology
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• v.38 no.3
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• pp.253-259
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• 2015

The information of contrast media concentration on target organ is very important to get reduce the side effect and high contrast imaging. We investigated alternation of signal intensity as a function of the modality of Gd-based contrast media on spin echo and ultra short time echo (UTE) of T1 effective pulse sequence at 3T MRI unit. Gadoxetic acid, which is a MRI T1 contrast medium, was used to manufacture an agarose phantom diluted in various molarities, and sterile water and agarose 2% were used as the buffer solution for the dilution. The gold standard T1 calculation was based on coronal single section imaging of the phantom mid-point with 2D Inversion recovery spine-echo pulse sequence MR imaging for testing of phantom accuracy. The 1-2mmol/L and 7mmol/L was shown the maximum signal intensity on spin echo and UTE respectively. We confirm the difference of contrast media concentration which was shown the maximum signal intensity depending on the T1 effective pulse sequence.

• Proceedings of the KSMRM Conference
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• 1999.11a
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• pp.52-52
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• 1999

• Journal of the Korean Chemical Society
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• v.39 no.5
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• pp.421-426
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• 1995

The hydrogels of hydrophilic three-dimensional methacrylate polymer networks were prepared from 2-hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethacrylate (EDGMA) in aqueous solution. The interaction of water with the hydrophilic methacrylate polymers in the hydrogels was studied by pulse NMR spectroscopy. The spin-lattice relaxation times (T1) of low water content hydrogels showed the different double environments, resulting in two spin-lattice relaxation times (T1a and T1b). The values of T1a and T1b were 16.4${\times}$10-3 sec and 58.2${\times}$10-3 sec for a p(HEMA)-(10% H2O) system, and 13.2${\times}$10-3 sec and 23.1${\times}$10-3 sec for a crosslinked EGDMA-p(HEMA)-(10% H2O) system, respectively. The spin-spin relaxation times (T2) of the hydrogels were also measured as a function of water content in the p(HEMA)-(H2O)n and crosslinked EGDMA-p(HEMA)-(H2O)n system. The values of T2 were approximately 10 times less than those of T1 in agreement with the principles of spin relaxations.