• 공업화학
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• 제8권4호
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• pp.551-559
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• 1997

유화형 액막을 이용하여 $D_2EHPA-Kerosene-Span$ $80-H_2SO_4$계에서 Zn 성분의 추출시 액막의 안정성에 영향을 미치는 에멀젼의 파괴, swelling 현상 및 에멀젼의 morphology를 조사하였다. Zn 성분의 추출시 액막의 안정성에 대한 최적 조건은 계면활성제 Span 80의 농도 2~3 vol.%, 추출담제 $D_2EHPA$의 농도 5~7 vol.%, 막강화제 paraffin oil의 농도 10 vol.% 였으며, 외부수용액에 대한 에멀젼의 비 0.1, 유기상에 대한 내부수용액의 비는 1.0이 적절하였다.

• 대한정형도수물리치료학회지
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• 제15권1호
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• pp.41-48
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• 2009

Purpose: to program introduction the effects of stability sling exercise and common exercise of high school in man volleyball player. Methods: This study divided the subjects into a sling-exercise group and a common exercise group to compare after practicing exercises twice per week for 8 weeks (total 16 times). To compare the means of the experimental group and the control group on each variable, the ANOVA for repeated measure was used and if there was any significant difference across the measurement times, post-hoc comparisons were conducted for the difference. Results: The T-tests for group difference according to exercise type on each of the variables showed the results as follows. The pain in cervical region is experimental and control groups pain correlation were not significant(p>0.05). But lumbar region experimental and control groups were significant(p<0.05). Muscle volume was increased during 8weeks in experimental and control groups. But experimental and control groups muscle volume correlation were not significant(p>0.05). Conclusion: Fat Mass composition was decreased during 8 weeks in experimental and control groups. But experimental and control groups mass composition correlation were not significant(p>0.05).

• 한국농공학회지
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• 제45권3호
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• pp.65-72
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• 2003

The objective of this study is to evaluate the stability of the design criteria recommended by Betram and Terzaghi as compared with the experimental result. A series of NEF tests was conducted to determine the loss of volume in base soils. The three kinds of base soils classified as CL, SC and SM are used for the NEF tests with various hydraulic pressures and filters following upper and lower bond of the criteria. Volume loss characteristics of the base soils was examined closely by the results of the test successfully. Firstly, it was found that the loss of base soils was mostly eroded at the first stage of seepage. Secondly, the amount of loss volume was ranked CL > SM > SC in order of their amounts for upper criteria, and SM > CL > SC orderly for lower criteria. Thirdly, the volume loss of all soils was increased with increasing the hydraulic pressures. And lastly, the needs of the new design criteria was proved for the control of seepage and piping.

• 한국자기학회지
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• 제10권5호
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• pp.232-236
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• 2000

Cr을 하지층으로 사용한 CoSm 박막은 고기록밀도 수평 자기기록 매체로 가능성이 커 이에 대한 관심이 집중되고 있다. 본 연구에서는 dc 마그네트론 스퍼터링법으로 제작한 CoSm 박막의 자기적 성질의 Ar 가스 스퍼터링 압력 의존성을 조사하였다. 특히 고기록밀도 자기기록 매체에서 magnetic switching volume V＊은 자기기록 매체에 기록된 정보의 열적 안정성, 자화반전 및 잡음을 이해하는데 중요한 자료가 된다. 따라서 본 연구에서는 동일 조건에서 제작한 하지층 Cr위에 스퍼터링 압력을 달리하여 자성층 CoSm을 성장시켜 switching volume의 스퍼터링 압력 의존성을 규명하도록 하였다. 연구 결과 switching volume은 스퍼터링 압력이 증가할수록 감소하며, 그 크기는 9.0-5.2$\times$$10^{-18}$ $cm^3$ 범위 내에 있었다. Switching volume V＊를 이용하여 계산한 switching 단위의 크기는 22 nm 보다 작으며, 이 크기는 고기록 밀도수평 자기기록매체의 열적 안정성에 대한 Sharrock 조건을 만족한다.

• Smart Structures and Systems
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• 제23권3호
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• pp.215-225
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• 2019

In the present paper, the nonlocal strain gradient refined model is used to study the thermal stability of sandwich nanoplates integrated with piezoelectric layers for the first time. The influence of Kerr elastic foundation is also studied. The present model incorporates two small-scale coefficients to examine the size-dependent thermal stability response. Elastic properties of nanoplate made of functionally graded materials (FGMs) are supposed to vary through the thickness direction and are estimated employing a modified power-law rule in which the porosity with even type of distribution is approximated. The governing differential equations of embedded sandwich piezoelectric porous nanoplates under hygrothermal loading are derived through Hamilton's principle where the Galerkin method is applied to solve the stability problem of the nanoplates with simply-supported edges. It is indicated that the thermal stability characteristics of the porous nanoplates are obviously influenced by the porosity volume fraction and material variation, nonlocal parameter, strain gradient parameter, geometry of the nanoplate, external voltage, temperature and humidity variations, and elastic foundation parameters.

• 분석과학
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• 제7권2호
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• pp.233-236
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• 1994

유중수적형 유화계의 유화안정지수를 산출하는 방법을 확립하기 위하여 간편하면서도 예민한 "부피 직접 측정법"을 개발하였는 바, 먼저 강력한 혼합기인 일종의 Ultra-turrax T25를 이용하여 유지방, 유화제 및 물로 구성되면서 유지방이 물보다 많이 함유되는 유중수적형의 유화계를 형성시킨 후 상온에서 시간이 경과함에 따라 분리되어지는 수분층의 부피를 측정하였으며, 유화안정지수는 $(1-V_s/V_a){\times}100$(단, $V_a$는 유화계내에 함유되어 있는 총 수분의 부피이며, $V_s$는 시간이 경과함에 따라 유화계로부터 분리되어지는 수분층의 부피를 의미한다)의 계산식에 대입하여 산출하였다. 한편, sorbitan trioleate, span 60 및 tween 20을 첨가하여 유중수적형 유화계를 형성시킨 후 90분이 경과한 다음 "부피 직접 측정법"에 의하여 유화안정지수를 산출하였는바, 각각 $95.4{\pm}1.8$, $56.1{\pm}2.8$ 및 $41.6{\pm}2.2$였으며, 이러한 값은 유화안정지수의 산출방법으로서 일반적으로 사용하고 있는 "Titus의 방법"과 비교해 볼 때 5.0 이내의 차이-유화안정지수가 평형에 도달하였을 때의 차이 값-를 나타냄을 알 수 있었다.

• 반도체디스플레이기술학회지
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• 제21권1호
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• pp.33-38
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• 2022

This study investigates the outlet temperature of coolant heater based on heat and flow volume conditions. Through computer simulation, the coolant temperature at the outlet was analyzed to investigate the heat and flow volume conditions of the coolant heater, and the optimal conditions were derived. Results show that heat and flow volume conditions, it was confirmed that heat condition is 0.424 W/mm³, and flow volume condition is 500 l/h, demonstrates optimal conditions. The results of this study can be utilized to efficiently control the coolant temperature through various heat and flow volume conditions.

• Journal of Information Processing Systems
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• 제15권4호
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• pp.820-832
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• 2019

Estimation of accurate blood volume flow in ultrasound Doppler blood flow spectrograms is extremely important for clinical diagnostic purposes. Blood volume flow measurements require the assessment of both the velocity distribution and the cross-sectional area of the vessel. Unfortunately, the existing volume flow estimation algorithms by ultrasound lack the velocity space distribution information in cross-sections of a vessel and have the problems of low accuracy and poor stability. In this paper, a new robust ultrasound volume flow estimation method based on multigate (RMG) is proposed and the multigate technology provides detail information on the local velocity distribution. In this method, an accurate double iterative flow velocity estimation algorithm (DIV) is used to estimate the mean velocity and it has been tested on in vivo data from carotid. The results from experiments indicate a mean standard deviation of less than 6% in flow velocities when estimated for a range of SNR levels. The RMG method is validated in a custom-designed experimental setup, Doppler phantom and imitation blood flow control system. In vitro experimental results show that the mean error of the RMG algorithm is 4.81%. Low errors in blood volume flow estimation make the prospect of using the RMG algorithm for real-time blood volume flow estimation possible.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2000년도 학술발표회 발표논문집
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• pp.477-483
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• 2000

Fly ash is the unburned residue resulting from the combustion of coal in utility and industrial boilers such as thermal power plants. Annually about 5 million tons of fly ash is being produced in korea. Less than 25 percent of total volume of fly ash is currently being used effectively for some ways. In the future, the volume of fly ash discharge from thermal power stations will be increasing more and more, and the development of the utilization of high volume fly ash is required. Fly ash has a lower compacted density and specific gravity than coarse grained natural aggregates but equivalent strength properties indicating that the fly ash could be used as a structural fill materials. So, clay-fly ash mixtures can be used as a fill material in the construction of embankments. Laboratory tests have been carried out to determine the physical, chemical, and geotechnical characteristics of the clay and fly ash. The fly ash is mixed with the clay in different proportions and the geotechnical characteristics of the mixtures have been studied also. In this study describes the results of the experimental study. The implications of the use of clay and clay-fly ash mixtures on the stability of embankments are discussed.

• 대한토목학회논문집
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• 제26권3A호
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• pp.533-538
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• 2006

이 논문은 단순지지된 변단면 기둥의 정적, 동적 안정해석에 관한 연구이다. 이 연구에서 기둥의 체적과 지간길이는 일정하다. 기둥의 단면은 정다각형 단면이고 단면깊이의 변화는 포물선형으로 채택하였다. 압축하중을 받는 이러한 기둥의 자유 진동을 지배하는 미분방정식과 경계조건을 무차원으로 유도하였다. 이 미분방정식을 수치해석하여 고유진동수와 진동형 및 좌굴하중을 산정하였다. 단면비와 고유진동수 및 좌굴하중의 관계를 분석하여 동적 최적단면비, 최적 고유진동수 및 최강기둥의 단면비 및 좌굴하중을 얻었다.