• Journal of the Korean Geotechnical Society
• /
• v.36 no.1
• /
• pp.17-28
• /
• 2020

This study presents the experimental results of ground improvement efficiency induced by enzyme-induced carbonate precipitation (EICP) in soils. First, the optimal mixture ratio of EICP solution was determined by comparing the amount of induced carbonate depending on the different ratio among urea, CaCl₂, and urease. Next, we evaluated the shear stiffness and strength of EICP-treated sandy soil by performing shear wave velocity measurement and triaxial shear test. Furthermore, induced carbonate in treated soil was visually investigated by X-ray CT and SEM analysis. The results showed that the maximum shear stiffness evolved 19~30 times after 6 hours of reaction time compared with non-treated sands. Also, the cohesion and the friction angle tended to increase and decrease, respectively, as the amount of induced carbonate increased.

• International Journal of Highway Engineering
• /
• v.10 no.4
• /
• pp.79-89
• /
• 2008

The pavement performance model is the most important factor to determine the pavement life in the mechanistic-empirical pavement design guide (MEPDG). As part of Korean Pavement Research Program (KPRP), the Korean Pavement Design Guide (KPDG) is currently being developed based on mechanistic-empirical principle. In this paper, the rutting prediction model of asphalt mixtures, one of the pavement performance model, has been developed using triaxial repeated loading testing data. This test was conducted on various types of asphalt mixtures for investigating the rutting characteristics by varying with the temperature and air void. The calibration process was made for the coefficients of rutting prediction model using the accelerated pavement testing data. The accuracy of prediction model can be increased when by considering the effect of individual rutting properties of materials rather than shear stresses with depths.

• Journal of Korea Water Resources Association
• /
• v.46 no.8
• /
• pp.795-805
• /
• 2013

Drought is one of the severe natural disasters and it can profoundly affect our society and ecosystem. Also, it is a very important variable for water resources planning and management. Therefore, the drought is analyzed in this study to understand the drought distribution and trend. The Standard Precipitation Index (SPI) is estimated using precipitation data obtained from 55 rain gauge stations in South Korea and the SPI based drought variables such as drought duration and drought severity were defined. Drought occurrence and joint probabilistic analysis for SPI based drought variables were performed with run theory and copula functions. And then the return period and spatial distribution of droughts on the South Korea was estimated. As the results, we have shown that Gongju and Chungju in Chungcheong-do and Wonju, Inje, Jeongseon, Taebeak in Gangwon-do have vulnerability to droughts.

• Korean Journal of Social Welfare
• /
• v.61 no.2
• /
• pp.61-84
• /
• 2009

There has been a continuous debate on decentralization of welfare. The proponents of decentralization argue that it will enhance the autonomy of local governments and the efficiency in the provision of service. However, the opponents argue that it will lead to the welfare reduction and the increased inequality among localities. This study attempts to deal with the question, focusing on the evaluation of decentralization reform of Roh Government. The main results are as follows: After the decentralization, local governments has undergone hardships in financing the welfare service, while there is no clear evidence that the local autonomy has enhanced. In respect of fiscal role-sharing, local duties has significantly increased because of the insufficient grants-in-aid for decentralization and inappropriate formula in assessing the grants. In respect of functional role-sharing, the decreased role of central government made it difficult for local governments to provide enough residential institution for the elderly and the disabled. To improve the decentralization reform, deliberate reclassification is needed to decide which item should be transferred to localities. Regarding the characteristic of the projects, social services could be transferred in the long run, while central government should take more responsibilities for the income guarantee and protection for the disadvantaged.

• 한국방재학회:학술대회논문집
• /
• 2008.02a
• /
• pp.195-198
• /
• 2008

In this study we analyzed flood runoff and flood characteristics of an small urban river basin which is in an apartment complex in Yewol-Dong, Buchun-Si, Gyunggi-Do. A little discharge normally flows in the river, however this small river has a relatively high potential of flood damage risk in the flood season due to the high flood level and velocity. Therefore we used the GIS data, cross section data in the river, HEC-RAS model, etc. for investigating safety of a river against flood runoff and also we investigated the stability of hydraulic structures and ability of flood prevention in the river. As the result of investigation, we found that the river had the risk of flood damage occurrence due to the hydraulic structures constructed for various purposes in the river. So we should analyze backwater effect by the structures and consider the risk factors can be occurred by the flood runoff and velocity for more safe design of a small river basin in the residential area such as an apartment complex in the urban area.

• Journal of Korean Society of Transportation
• /
• v.20 no.7
• /
• pp.59-67
• /
• 2002

2001년 경찰청 $\ulcorner$2001년판 교통사고통계$\lrcorner$ 자료에 의하면 사고피해의 정도를 나타내는 치사율에 있어서 중앙선침범사고가 과속사고와 함께 가장 높은 수치를 보이고 있으며, 대형 교통사고의 39.5%가 중앙선 침범에 의해 발생한 것으로 나타났다. 실제로 2000년 한 해 동안 총 사고건수 290,481건 중 중앙선 침범에 의해 18,931건 (6.52%)의 교통사고가 발생하여 사망자 1,472명, 부상자 35,046명으로 전체 교통사고 사망자의 14.38%, 부상자의 8.21%를 점하고 있는 것으로 나타났다. 이와 같이 전체 교통사고에서 중앙선침범사고가 차지하는 비중 이 높아지고 있어 중앙선침범사고를 줄이기 위한 대책의 일환으로 중앙분리대, 표지병, 시선 유도봉 등과 같은 중앙선침범 예방시설물을 설치하고 있으나, 해당 시설물에 대한 설치기준이 없는 실정이다. 이렇듯 중앙분리대 설치기준의 부재로 인해 중앙선침범사고 발생과 이에 따르는 경제적인 교통사고 비용손실, 그리고 중앙분리대의 과다설치로 인한 국가 재원의 낭비는 간과할 수 없는 문제점을 내포하고 있다. 이러한 점에 착안하여 기존에 지방부 2차로 도로의 직선부에 대한 중앙선침범사고 예측모델이 개발되었고 본 연구에서는 그 연장선상에서 지방부 2차로 도로의 곡선부에 대한 중앙선침범사고 예측모델에 대한 중앙선침범사고 예측모델의 개발을 통해 중앙선침범사고에 대한 사회적 비용을 산정하고, 현재 설치하여 운영중인 중앙선침범 예방시설물의 설치비용간의 비용-편익분석을 통해 얻어진 기준으로 중앙선침범 예방시설물 설치의 가부에 대한 보다 현실적이고 비용-효율적인 중앙선침범 예방시설물 설치기준을 제시함으로써 교통사고 비용손실을 최소화하고, 중앙분리대의 효율적 설치방안의 도입을 통한 경제적 이익창출을 도모하고자 한다.

• Journal of Korean Society of Transportation
• /
• v.20 no.7
• /
• pp.87-94
• /
• 2002

2001년 경찰청 $\ulcorner$2001년판 교통사고통계$\lrcorner$ 자료에 의하면 사고피해의 정도를 나타내는 치사율에 있어서 중앙선침범사고가 과속사고와 함께 가장 높은 수치를 보이고 있으며, 대형 교통사고의 39.5%가 중앙선 침범에 의해 발생한 것으로 나타났다. 실제로 2000년 한 해 동안 총 사고건수 290,481건 중 중앙선 침범에 의해 18,931건 (6.52%)의 교통사고가 발생하여 사망자 1,472명, 부상자 35,046명으로 전체 교통사고 사망자의 14.38%, 부상자의 8.21%를 점하고 있는 것으로 나타났다. 이와 같이 전체 교통사고에서 중앙선침범사고가 차지하는 비중 이 높아지고 있어 중앙선침범사고를 줄이기 위한 대책의 일환으로 중앙분리대, 표지병, 시선 유도봉 등과 같은 중앙선침범 예방시설물을 설치하고 있으나, 해당 시설물에 대한 설치기준이 없는 실정이다. 이렇듯 중앙분리대 설치기준의 부재로 인해 중앙선침범사고 발생과 이에 따르는 경제적인 교통사고 비용손실, 그리고 중앙분리대의 과다설치로 인한 국가 재원의 낭비는 간과할 수 없는 문제점을 내포하고 있다. 이러한 점에 착안하여 기존에 지방부 2차로 도로의 직선부에 대한 중앙선침범사고 예측모델이 개발되었고 본 연구에서는 그 연장선상에서 지방부 2차로 도로의 곡선부에 대한 중앙선침범사고 예측모델에 대한 중앙선침범사고 예측모델의 개발을 통해 중앙선침범사고에 대한 사회적 비용을 산정하고, 현재 설치하여 운영중인 중앙선침범 예방시설물의 설치비용간의 비용-편익분석을 통해 얻어진 기준으로 중앙선침범 예방시설물 설치의 가부에 대한 보다 현실적이고 비용-효율적인 중앙선침범 예방시설물 설치기준을 제시함으로써 교통사고 비용손실을 최소화하고, 중앙분리대의 효율적 설치방안의 도입을 통한 경제적 이익창출을 도모하고자 한다.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.20 no.6
• /
• pp.501-510
• /
• 2000

Recently, advanced signal analysis which is called "time-frequency analysis" has been used widely in nondestructive evaluation applications. Wavelet transform(WT) and Wigner Distribution are the most advanced techniques for processing signals with time-varying spectra. Wavelet analysis method is an attractive technique for evaluation of material characterization nondestructively. Wavelet transform is applied to the time-frequency analysis of ultrasonic echo waveform obtained by an ultrasonic pulse-echo technique. In this study, the feasibility of noise suppression of ultrasonic flaw signal and frequency-dependent ultrasonic group velocity and attenuation coefficient using wavelet analysis of ultrasonic echo waveform have been verified experimentally. The Gabor function is adopted the analyzing wavelet. The wavelet analysis shows that the variations of ultrasonic group velocity and attenuation coefficient due to the change of material characterization can be evaluated at each frequency. Furthermore, to assure the enhancement of detectability and naw sizing performance, both computer simulated results and experimental measurements using wavelet signal processing are used to demonstrate the effectiveness of the noise suppression of ultrasonic flaw signal obtained from austenitic stainless steel weld including EDM notch.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2018.05a
• /
• pp.311-311
• /
• 2018

Generally, the water resources in South Korea were supplied from river flow and dam. Among them, the dam is the most important supplier for the residential and industrial water. However, the climate change has caused a setback in water supply chain. The objective of the study is therefore to suggest a drought index consideing dam water shortage for efficiently dam and water resources management. The standardzied balanced index(SBI), which has same concept with the standardzied precipitation index, were suggested. Also, the management index for the dam were established with SSVI and the storage percentage that compared to previous years.

• Journal of Korea Water Resources Association
• /
• v.54 no.7
• /
• pp.545-552
• /
• 2021

The burden of flood control on the dam under frequently flood due to climate change and especially heavy flood in 2020 year are come to the forward and increased. The objective of the study is therefore to establish the method to estimate capacity and target water level for flood control in actual dam management. Frequency matching method was applied to establish a pair of cumulative distribution function (CDF) based on daily dam inflow and discharge records. The relationship between dam storage and discharge volume represented as a percentage of inflow volume was derived and its characteristics was analyzed. As the result, the Soyanggang (45%) and Chungju Dam (39%) contributing to flood control with temporarily storing flood runoff. The method and diagram to estimate flood control capacity and target water level for flood control in the dam were established. The result of the study could be used as a supplementary data for flood control of the dam according to the rainfall prediction on the Korea Meteorological Administration.