• 대한화학회지
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• 제56권4호
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• pp.424-430
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• 2012

Densities, viscosities, refractive indices and speed of sounds of the binary mixtures of Acetophenone with Ethylchloroacetate were measured over the entire mole fractions at (303.15, 313.15 and 323.15) K. From these experimental results, excess molar volume $V^E$, viscosity deviation ${\Delta}{\eta}$, refractive index deviation ${\Delta}n_D$, deviations in speed of sound ${\Delta}u$, deviations in isentropic compressibility ${\Delta}k_s$ and excess intermolecular free length ${\Delta}L_f$ were calculated. The viscosity data have been correlated with the equations of Grunberg and Nissan, Hind et al., Tamura and Kurata, Katti and Chaudri, Sedgwick, Krishnan-Laddha and McAllister. The thermo physical properties under study were fit to the Jouyban-Acree model. The excess values were correlated using Redlich-Kister polynomial equation to obtain their coefficients and standard deviations. It was found that in all cases, the data obtained fitted with the values correlated by the corresponding models very well. The results are interpreted in terms of molecular interactions occurring in the solution.

• 한국군사과학기술학회지
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• 제20권3호
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• pp.405-412
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• 2017

In the present study, two phase flows around a projectile vertically launched from an underwater platform have been numerically investigated by using a three dimensional multi-phase RANS flow solver based on pseudo-compressibility and a homogeneous mixture model on unstructured meshes. The relative motion between the platform and projectile was described by six degrees of freedom(6DOF) equations of motion with Euler angles and a chimera technique. The propulsive power of the projectile was modeled as the fluid force acting on the lower surface of the body by the compressed air emitted from the platform. Qualitative analysis was conducted for the time history of vapor volume fraction distributions. Uncorking pressure around the projectile and platform was analyzed to predict impact force acting on the surfaces. The results of 6DOF analysis presented similar tendency with the surficial pressure distributions.

• 대한화학회지
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• 제33권6호
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• pp.582-587
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• 1989

$[Cr(NH_3)_5(DMF)]^{3+}$ 이온의 수화반응 속도를 분광광도법을 이용하여 온도와 압력을 변화시켜 가면서 측정하였다. 활성화부피(${{\Delta}V_0}^{\neq}$)는 -2.76∼-3.65$cm^3mol^{-1}$의 범위로 작은 음의 값을 나타내었다. 활성화 엔트로피(${\Delta}S^{\neq}$) 및 활성화 압축률계수(${\Delta}{\beta}^\neq$)도 모두 작은 음의 값을 가졌다. 이러한 열역학적인 활성화 파라미터로부터 이 착이온의 수화반응은 교환회합($I_a$) 메카니즘으로 진행됨을 알 수 있었다.

• 한국가시화정보학회지
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• 제10권1호
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• pp.40-46
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• 2012

Recently micro shock tube is extensively being used in many diverse fields of engineering applications but the detailed flow physics involved in it is hardly known due to high Knudsen number and strong compressibility effects. Unlike the macro shock tube, the surface area to volume ratio for a micro shock tube is very large. This unique effect brings many complexities into the flow physics that makes the micro shock tube different compared with the macro shock tube. In micro shock tube, the inter- molecular forces of working gas can play an important role in specifying the flow characteristics of the unsteady shock wave flow which is essentially generated in all kinds of shock tubes. In the present study, a CFD method was used to predict and visualize the unsteady shock wave flows using the unsteady compressible Navier-Stokes equations, furnished with the no-slip and slip wall boundary conditions. Maxwell's slip equations were used to mathematically model the shock movement at high Knudsen number. The present CFD results show that the propagation speed of the shock wave is directly proportional to the initial pressure and diameter of micro shock tube.

• 대한화학회지
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• 제36권4호
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• pp.517-522
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• 1992

10$^{\circ}C$와 20$^{\circ}C$에서 ${\beta}$-피콜린과 치환된 벤조일클로라이드류의 반응을 압력변화에 따라 아세토니트릴용매내에서 전기전도도법으로 연구하였다. 유사 1차속도상수와 2차속도상수로부터 여러 가지 활성화파라미터들(${\Delta}V{\neq}$, ${\Delta}{\beta}{\neq}$, ${\Delta}H{\neq}$, ${\Delta}S{\neq}$ and ${\Delta}G{\neq}$)을 구하고, Hammett ${\rho}$값의 압력의존성을 설명하였다. ${\Delta}V{\neq}$, ${\Delta}{\beta}{\neq}$ 및 ${\Delta}S{\neq}$ 는 모두 음의 값을 나타내었고, 압력증가에 따라 속도상수와 Hammett ${\rho}$값은 증가하며, 결합형성이 더욱 촉진된 반응메카니즘으로 진행됨을 알 수 있었다.

• 대한화학회지
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• 제36권2호
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• pp.180-184
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• 1992

Acetonitrile 용매내에서 pyridine과 치환된 benzoyl chloride류의 반응을 압력변화(1-1000 bar)에 따라 속도론적으로 연구하였다. 속도상수로부터 활성화파라미터들(Δ$V^{\neq}$, ${\Delta}{\beta}^{\neq}$, ${\Delta}H^{\neq}$, ${\Delta}S^{\neq}$ and ${\Delta}G^{\neq}$)을 구하였다. 압력이 증가함에 따라 속도상수는 증가하고 ${\Delta}V^{\neq}$, ${\Delta}{\beta}^{\neq}$, 및 ${\Delta}S^{\neq}$는 모두 음의 값을 나타내었으며, 치환기효과와 종합하여 반응메카니즘을 고찰한 결과 전체적인 반응은 $S_N2$ 반응메카니즘으로 진행되나, 치환체와 압력변화에 따라 전이상태 구조에 약간의 변화가 있으리라 생각된다.

• 한국농공학회지
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• 제18권4호
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• pp.4242-4250
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• 1976

The determination of the pre-consolidation load known to have a great effect on the consolidation characteristics of the soil have been researched and discussed in detail by many other researchers. A study was undertaken to investigate and compare the effect of pre-consolidation loads on the coefficient of permeability and the consolidation characterisics of soil through the consolidation test on the three types of soil samples. The results of this study are follows; 1. Large compression index is dependent on initial void ratio of the sample being used and the pressure-void ratio curve shows a curved linear relationship in over-consolidated area but a linear relationship in normally consolidated area.2. Settlement-time curve is S-shaped where the pressure is larger than pre-consolidation load and regardless of over-burden pressure, it is a similar straight line respectively in the secondary consolidation area. 3. Primary consolidation ratio of the sample increases almost linearly with the increase of over-burden pressure but the coefficient of volume compressibility decreases linearly with the increase of it. 4. Time factor of a certain degree of consolidation increases with over-burden pressure but the coefficient of consolidation decreases with it in over-consolidated area. There is a linear relationship between them in normally consolidated area. 5. The void ratio of completion point of primary consolidation decreases linearly with over-burden pressure. 6. The coefficient of permeability of sample decreases linearly with over-burden pressure in normally consolidated area, also it increases linearly with increment of the void ratio of the sample.

• 한국지반공학회지:지반
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• 제4권4호
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• pp.5-18
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• 1988

본 연구는 인공연약점토를 시료로 하여 미려밀점토의 비배수 전단강도가 압밀과정에서 어떻게 변 이되는가를 고색하고 그 결과를 점토련자가 상당한 속도를 가지고 지적적으로 퇴적하고 있는 해천 모면에 적용하여 사면의 안정성을 검토하였다. 비배수 삼동려축 전단강도는 여밀도가 증가함에 따라 포물선을 그리며 증가하였고 유효응력과는 불 가분의 관계가 있음이 고찰되었다. 사면안정 검토에는 실험결과치들이 유한요소 프로그램에 입력되 감으며 흙의 여축성과 투수계수도 여밀도에 따라 변화시켰다. 퇴적률, 여밀도간의 관계와 사면붕괴시점과 이동토최예측도가 제시되었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.449-456
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• 2009

As soft grounds have complex engineering properties that the load bearing capacity is low and high compressibility, it needs to solve this problems prior to structures are constructed by the method of improvement of soft ground. Generally, the sand mat is used to as a horizontal drain material and loading base for soft ground improvement work. However, as the natural environment can be damaged by sand pickings of large quantity and the volume which is enormous and an amount of demanded sand is increased, it is state of short in supply. This paper presents the result of field experimental test to use Precious Slag Ball to solve these issues instead of sand mat as the replacing material. This study evaluated the performance of Precious Slag Ball as a sand mat in terms of discharge capacity, settlement, and settlement through the K-Embank program.

• Korean Chemical Engineering Research
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• 제56권5호
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• pp.663-678
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• 2018

Refractive index and speeds of sound for the binary mixture of isomer of butanol (1) + cyclohexane, benzene and toluene (2) were measured at 308.15 K. The measured data were used to calculate deviation in refractive index ${\Delta}n$, ultrasonic speed ${\Delta}u$, isentropic compressibility $K_s^E$, available volume $V_a$, excess intermolecular free length $L_f$ and molecular association $M_A$. All the derived properties were correlated with polynomial equation. Ultrasonic speed data were predicted using various empirical correlations like Nomoto, van Dael, impedance dependence and theoretically with Schaaff's collision factor theory (CFT). Jacobson free length theory (FLT) was used to calculate $L_f$. The measured refractive index was also correlated with various mixing rules. The deviation in refractive index Δn and ultrasonic speed ${\Delta}u$ was used to determine the intermolecular interactions.