• Journal of the Korean Geotechnical Society
• /
• v.20 no.5
• /
• pp.145-159
• /
• 2004

The conventional method for assessment of liquefaction potential proposed by Seed and Idriss has been widely used in most countries because of simplicity of tests. Even though various data such as stress, strain, stress path, and excess pore water pressure can be obtained from the dynamic test, especially, two simple experimental data such as the maximum deviatoric stress and the number of cycles at liquefaction have been used in the conventional assessment. In this study, a new detailed assessment for liquefaction potential to reflect both characteristics of real earthquake motion and dynamic soil resistance is proposed and verified. In the assessment, the safety factor of the liquefaction potential at a given depth of a site can be obtained by the ratio of a resistible cumulative plastic shear strain determined through the performance of the conventional cyclic test and a driving cumulative plastic shear strain calculated from the shear strain time history through the ground response analysis. The last point to cumulate the driving plastic shear strain to initiate soil liquefaction is important for this assessment. From the result of cyclic triaxial test using real earthquake motions, it was concluded that liquefaction under the impact-type earthquake loads would initiate as soon as a peak loading signal was reached. The driving cumulative plastic shear strain, therefore, can be determined by adding all plastic shear strains obtained from the ground response analysis up to the peak point. Through the verification of the proposed assessment, it can be concluded that the proposed assessment for liquefaction potential can be a progressive method to reflect both characteristics of the unique soil resistance and earthquake parameters such as peak earthquake signal, significant duration time, earthquake loading type, and magnitude.

• Proceedings of the Korean Society of Developmental Biology Conference
• /
• 2003.10a
• /
• pp.79-79
• /
• 2003

세포에 대한 산화스트레스는 세포의 대사와 기능저하의 원인이 되고 있으며 이를 줄이기 위한 항산화 물질의 첨가가 연구되고 있다. 본 연구는 비특이면역증가제이며 다목적 고기능성 알칼리용액 조성물인 Barodon의 항산화 효과를 돼지정자를 이용하여 조사하여, 돼지 액상정액의 보존성 향상을 위한 Barodon의 이용성을 알기 위하여 시도하였다. 실험구로서 무첨가구와 활성산소 인위발생구(xanthine+xanthine oxidase, X-XO), X-XO구에 superoxide dismutase, cataiase, Barodon(2종류)의 단독처리구 및 X-XO구에 이들 항산산제의 복합처리구로 나누어 항산화제 처리효과에 따른 정자운동특성을 CASA로 분석하였다. 또한 돼지 액상정액에서 Barodon의 항산화 효과를 무첨가구, catalase구 및 Barodon구로 나누어 정액의 보존기간별 정액성상 변화(정자활력, 생존성, 첨체이상)를 조사하였다.

• Journal of Animal Environmental Science
• /
• v.14 no.2
• /
• pp.97-104
• /
• 2008

Appropriate air quality in the pig building is essential to prevent farmers' health as well as to increase pig performance. This on-site experiment was conducted to assess dust reduction efficiencies of several liquid additives with spaying method in the enclosed pig building. The mean reduction rate of total dust only after spray was approximately 30% for all the treatments compared to initial level before spraying additives, which was found to reduce the initial level of total dust significantly (p<0.05). The mean reduction rate of all the treatments at 1hr after spray was about 24% which was 6% lower than only after spray. Since 3hr after spray, however, total dust level were fluctuated variably for all the treatments besides application of the soybean oil. Based on this result, effect of soybean oil on dust reduction in the enclosed pig building was most prominent among liquid additives evaluated in terms of efficiency and duration.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.1
• /
• pp.66-73
• /
• 2022

The purpose of this study was to develop self-heating concrete by utilizing the conduction resistance of concrete in order to reduce the risk of occurrence of black ice in the concrete pavement in winter and to prevent damage caused by freez-thawing effect. For this purpose, it was attempted to evaluate the strength and temperature exothermic characteristics using powder and liquid waste CNTs and a waste cathode agent as a conduction promotion. It was analyzed that liquid waste CNT had an effective dispersion degree in the mortar and a small decrease in strength occurred. In addition, DC 24 V was supplied by applying steel mesh, copper foil and copper wire to the mortar as electrodes, and the temperature change characteristics according to the mixing ratio of spent CNTs, anodes and carbon fibers were evaluated. In addition, by evaluating the temperature characteristics according to the electrode spacing from the selected optimal mixture, it was confirmed that it had sufficient heating characteristics up to an electrode spacing of 100 mm up to AC 50 V.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.8
• /
• pp.147-158
• /
• 2004

Laboratory dynamic tests are carried out to assess the liquefaction potential of saturated sands in most countries. However, simple results such as the maximum cyclic shear stress and the number of cycles at initial liquefaction are used in the experimental assessment of liquefaction potential, even though various results can be obtained from the dynamic test. In addition, it seemed to be inefficient because more than three dynamic tests with different stress ratio have to be carried out to draw a liquefaction resistance experimental curve. To improve the present assessment method fur liquefaction potential, a new critical resistible characteristic far soil liquefaction is proposed and verified through conventional cyclic triaxial tests with Jumunjin sand. In the proposed method, various experimental data such as effective stress path, stress-strain relationship, and the change of excess pore water pressure can be used in the determination of cumulative plastic shear strains at every 1/4 cycle. Especially, the critical cumulative plastic shear strain to initiate liquefaction can be defined in a specific point called a phase change point in the effective stress path and it can be calculated from a hysteric curve of stress-strain relationship up to this point. Through this research, it is found that the proposed cumulative plastic shear strain can express the dissipated energy to resist dynamic loads and consider the realistic soil dynamic behavior of saturated sands reasonably. It is also found that the critical plastic shear strain can be used as a registible index of soils to represent the critical soil dynamic state, because it seems to include no effect of large deformation.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.2C
• /
• pp.83-94
• /
• 2008

In this study an effective stress analysis was performed to evaluate liquefaction potential and ground settlement for reclaimed sites. The effective stress model can simulate the stiffness degradation due to excess pore pressure and resulting ground deformation. It is applicable to a wide range of strain. An equivalent linear analysis suitable for low strain levels was also carried out to compare the effective stress analysis. Shear stress ratio calculated from an equivalent linear analysis was used to determine SPT blow count to prevent liquefaction. Depending on the magnitude of potential earthquake and fine contents, the SPT blow count was converted into an equivalent cone tip resistance. It was compared with the measured cone tip resistance. The measured elastic shear wave velocity and cone tip resistance from two reclaimed sites in Incheon were used to perform liquefaction analyses. Two liquefaction evaluation methods showed similar liquefaction potential which was evaluated continuously. The predicted excess pore pressure ratio of upper 20 m was between 40% and 70%. The calculated post-shaking settlement caused by excess pore pressure dissipation was less than 10 cm.

• Cement
• /
• s.172
• /
• pp.52-60
• /
• 2006

• Journal of the Korean Institute of Gas
• /
• v.14 no.2
• /
• pp.22-26
• /
• 2010

In this study, experimental vapor pressures and densities of vapor and liquid phases versus temperature were estimated using PC-SAFT equation. The estimated results were compared with those using PR equation of state. For the vapor phase densities, both equations well predicted the literature data. However, PC-SAFT equation showed better prediction capability for liquid phase densities. In the comparison of vapor-liquid equilibrium prediction capability for the binary systems of methane and ethane, PC-SAFT equation was better than the PR equation.

• Proceedings of the Korea Association of Crystal Growth Conference
• /
• 1997.10a
• /
• pp.27-31
• /
• 1997

액상법에 의한 단분산 ZnS입자의 합성을 60~9$0^{\circ}C$에서 행하여, 반응조건이 ZnS입자의 형태에 미치는 효과를 검토했다. ZnS입자의 형태는 반응 시간의 경과와 더불어 단분산으로부터 다분산 혹은 응집체로 변화하였다. 반응 온도 60~9$0^{\circ}C$에서 초기 농도적이 중간값이고, 반응시간이 짧을 경우 입경 0.2~0.8$\mu\textrm{m}$의 구상 단분산 입자를 얻었다. 또한 Ag$_2$NO$_3$, EtOH용액, $0^{\circ}C$에서, Ag$_2$S에 의한 ZnS의 균일 피복이 가능하였다.

• Proceedings of the Korean Society of Embryo Transfer Conference
• /
• 2003.10a
• /
• pp.79-79
• /
• 2003