• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.1177-1181
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• 2010

Unsaturated soil can describe soil particles, air-water and contact face between air and water. The providing a simple method to predict water content in Geotechnical mechanics is very important. In this experiment, DIP (Digital Image Processing) and electrical resistivity techniques were used simultaneously to predict the saturation degree, and the results of two techniques will be compared each other to get conclusion. The experiment was carried out for Jumunjin standard sand. The picture of experimental column of soil and water was taken at different times, then using DIP technique to measure Color number-the height of capillary in soil column. At the same time, measure electrical resistivity of the soil.

• 전기학회논문지
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• 제59권8호
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• pp.1464-1470
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• 2010

In this paper, we consider the $H_{\infty}$ control of time-delayed linear systems with saturating actuators. The considered time-delay is a time-varying one having bounds on magnitude and time-derivative, and the control permits the predetermined degree of saturation. Based on two modified Lyapunov-Krasovskii(L-K) functionals, we derive a $H_{\infty}$ control in the form of linear matrix inequalities(LMI) having three non-convex design parameters. The result is dependent on the characteristics of time-delay, predetermined degree of saturation level, and bound of disturbance. Finally, we give a comparative example to show the effectiveness and usefulness of our result.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.649-655
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• 2010

Unsaturated compressive tests are performed to evaluate the effect of matric suction on the strength and the deformation characteristics for statically compacted natural kaolin in Korea. Under different conditions of the initial degree of saturation in kaolin, the relationship between suction and the degree of saturation at failure can be expressed by unique soil-water characteristic curve. These results demonstrate that the newly established constant water content type unsaturated shear strength test equipment can be used for estimating the relationship between suction and the compressive strength.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.329-336
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• 2002

The earth structures and in-ground LNG tank, and buildings can be constructed with using artificial freezing method on the reclaimed land. In this study, upon freezing a saturated soil in a closed-system from the top, a considerable pressure was developed. The pressure is the result of the surface energy of a curved ice-water interface. The most significant of these parameters will have the greatest effect on the classification. In order to establish frost-susceptibility criteria based on frost heaving expansion pressure, more soils have to be tested. This study was initiated to investigate the soils frost heaving expansion pressure and moisture characteristics resulting from freezing and freezing-thawing cycle process. Weathered granite soils, sandy soil, sandy soil were used in the laboratory freezing test subjected to thermal gradients under closed- systems.

• 한국철도학회논문집
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• 제8권1호
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• pp.57-62
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• 2005

The frost heaving pressure can be a problem for weakening of the railway roadbed material. This study was initiated to investigate the soils frost heaving pressure and physical characteristics(Liquid limit, permeability, SEM analysis) resulting from freezing and freezing-thawing cycle process. Therefore, upon freezing a saturated soil in a closed-system from the top, a considerable pressure was developed. Weathered granite soils, sandy soil were used in the laboratory freezing test which sometimes subjected to thermal gradients under closed-systems. The frost heaving pressure arising within the soil samples and the temperature of the samples inside were monitored with elapsed time. The degree of saturation versus heaving pressure curve is also presented for weathered granite soil and the maximum pressure is closely related to this curve. Based on the laboratory test results, fine-grained soils with strong attractive forces between soil grains md water molecules, and additional water is attracted into the pores leading to further volume changes and ice segregation.

• Journal of Korean Biological Nursing Science
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• 제3권2호
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• pp.35-50
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• 2001

This study was conducted for the evaluation of the effects of singing program combined with physical exercise on the physiologic changes, perception function and degree of depression. The subjects were the members of elderly women's glee club in D care center for the elderly, who have been singing for more than 6 months. 30 members were allocated to study group and 30 to control group. The singing program designed for both physical therapy and music therapy was consisted of initial physical exercise, singing art songs and classical song and the finishing physical exercise. This program was performed twice a week and about forth minutes was consumed for one session. We checked the heart rate, peripheral arterial oxygen saturation, perception function and degree of depression before and after the program. We used a pulse oxymeter to check the heart rate to oxygen saturation and a questionnaire for the evaluation of perception function and degree of depression. We need SPSS program for data analysis. The results of the investigated personnel complying with general characteristics were analyzed by frequency, two groups by t-test, data before and after the program by paired t-test, respectively. The results were as follows. 1) Heart rate after the program was significantly lower than that before program in test group(p<0.05). 2) Peripheral oxygen saturation after the program was significantly higher than that before the program(p<0.05). 3) Ability to match the right sign with a certain predetermined number was improved after the program. The frequency of wrong matching the sign with number before program was 30. But the frequency was decreased to 8 after the program. 4) Ability to calculate was improved after the program. The frequency of wrong calculation before the program was $1.10{\pm}1.94$. But the frequency after the program was decreased to $0.97{\pm}1.84$. 5) The degree of depression after the program($2.07{\pm}0.49$) was significantly lower than that before program(p<0.001). These results show that singing program combined with physical exercise improves the oxygen delivery to peripheral circulation, stability of heart function, the perception function(calculating and matching ability) and decreases the degree of depression. In conclusion, singing program combined with physical exercise can be used for the effective measure to improve the health of elderly and prevent dementia.

• Restorative Dentistry and Endodontics
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• 제21권2호
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• pp.470-488
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• 1996

The end products of the metabolism of the oral microorganism, organic acids, are an element that produces dental caries. Four organic acids in plaque fluid, lactic acid, acetic acid, succinic acid, propionic acid which take the important role in producing dental caries, were chosen to evaluate the effect of acid type and concentration. The subject, $100{\mu}m$ in thickness, were immersed in acid-buffer solution which has the different acid concentration of 10mM, 25mM, 50mM, 100mM and pH 4.3 and degree of saturation was $0.153{\pm}0.003$ kept in constant and were operated to produce artificial caries under different demineralization time (1, 2, 3 day) at x25. The results were obtained by observing under polarizing microscope at x25. 1. The subsurface lesion, specific finding of incipient enamel caries, showed positive birefringence. but surface zone and sound enamel showed negative birefringence. 2. The demineralization rate of enamel was increased as the acid concentration increased. 3. The subsurface lesion showed increasing depth in the order of lactic, acetic, propionic acid, succinic acid. 4. The concentration of organic acid in artificial caries system had an independent effect on demineralization rate in enamel under the constant pH and degree of saturation. The result of this study showed that not only pH and the acid strength but the concentration of organic acid had an independent effect on demineralization rate in early enamel caries. And through the further research on the factors influencing enamel demineralization, it will be necessary to develop an effective caries preventive therapy.

• 대한토목학회논문집
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• 제35권2호
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• pp.515-524
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• 2015

최근 궤도 접속부에서의 부등침하 및 궤도틀림으로 잦은 유지보수 및 열차운영에 지장을 초래하는 경우가 많아지고 있다. 이는 주로 궤도 접속부 시공에 사용되는 다양한 성토재료의 강우나 동결융해 같은 환경적 인자에 의한 역학적 물성들의 변화에 기인한 것으로, 본 연구에서는 궤도 접속부 성토재료에 대한 함수특성곡선을 산정하고 강우 시 포화도 변화 추이를 알아보고자 침투해석을 수행 하였다. 필터페이퍼를 이용하여 다짐 성토의 함수특성곡선을 성공적으로 산정할 수 있었고, 함수특성곡선 데이터를 이용한 강우 시 침투해석을 수행한 결과 궤도 접속부 성토재료의 포화도 분포는 강우강도, 뒤채움재 경사, 성토 및 절토 여부, 그리고 함수특성곡선에 큰 영향을 받는 것을 확인 하였다.

• 한국철도학회논문집
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• 제18권2호
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• pp.127-138
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• 2015

본 연구에서는 국내 철도 궤도하부 다져진 흙노반의 강성 평가를 위하여 Stokoe 방식의 고정단-자유단 중형 공진주 시험기(D=10cm, L=20cm)를 이용, 구속압 및 전단변형률 증가시 포화도(S)변화에 따른 전단탄성계수의 분포변화를 조사, 분석하였다. 분석결과 포화도가 증가할수록 최대전단탄성계수는 감소하고 정규화 전단탄성계수는 증가하는 경향을 보였다. 분석결과를 바탕으로 포화도(S)~전단탄성계수(S)~전단변형률(${\gamma}$) 사이의 고유한 감소 관계특성을 관찰할 수 있었다. 이러한 특성수립 가능성을 기반으로 향후 광범위한 추가시험을 통하여 예측모델을 수립하고 소정의 모델계수 값들을 획득할 수 있을 것이다.

• Restorative Dentistry and Endodontics
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• 제34권1호
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• pp.20-29
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• 2009

법랑질의 재광화에 영향을 주는 요인으로는 pH, 불소 농도, 포화도 등이 있다. 본 연구에서는 유산 완충 탈회용액을 이용하여 법랑질 시편을 인공 탈회시킨 후, pH 4.3에서 포화도를 0.22, 0.30, 0.35로 달리한 세가지 재광화 용액에 10일간 처리하여 나타나는 변화를 편광현미경으로 관찰하여 전체 탈회 깊이와 건전 표층 폭의 변화를 조사하였다. 또한 Image program (Scion Image analyzer)을 이용하여 병소 부위의 평균 mineral density를 측정하여 탈회와 재광화 후 무기질 변화량을 통해 인공 탈회된 법랑질의 동력학적 변화를 관찰하였다. 1. 재광화 후 모든 군에서 건전 표층의 폭이 증가하였는데, 포화도가 증가할수록 건전 표층 폭이 증가하였다 (P<.05). 2. 재광화 후 mineral density 변화를 관찰한 결과, 포화도가 낮은 군에서는 이온의 침착이 병소 전반적으로 일어났으나, 포화도가 높은 군에서는 건전 표층 부위와 표층하 병소의 하층부에서 이온의 침착으로 mineral density 가 증가하였고 표층하 병소의 상층부에서는 탈회가 진행되어 mineral density 가 감소하였다. 3. 재광화 후 모든 군에서 무기질량이 증가하였고 전체 탈회 깊이도 증가하였으나 각 군간에 통계적 유의차는 없었다. 본 실험에서 인공 탈회된 시편을 pH 4.3인 재광화 용액에 처리시 포화도가 높을수록 건전 표층에서 더 많은 재광화 현상이 일어났고 표층하 병소에서는 재광화 현상이 적게 일어났으며, 재광화 후 모든 군에서 전체 탈회 깊이는 증가하였다.