박미정 Park Meejeong , 허현 Heo Hyun , 김태곤 Kim Tae-gon , 서교 Suh Kyo , 이정재 Lee Jeong-jae

DOI: JKWST Vol.48(No.4) 3-12, 2006

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Watershed is the land area that contributes runoff to an outlet point. To delineate an watershed, watershed delineation using GIS that contains grid data structure is the most general method. Some researchers have studied to implement algorithms that revise the TIN topography since it is difficult to delineate watershed boundary more accurately. In this study kruskal's greedy algorithm and triangulated irregular network (TIN) were used to delineate a watershed. This method does not require a conversion from to DEM in grid and automatically obtain(generates) the oulet points. Delineation algorithm was tested in Geosan-gun, Chung-cheongbuk-do and get small watershed areas. Finally, kruskal's algorithm could operate more precisely with revision algorithm.

이상호 Lee Sang Ho , 김진호 Kim Sang Chul , 김상철 Kim Jin Ho

DOI: JKWST Vol.48(No.4) 15-22, 2006

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This study was conducted by the slump test and the consistency test of the cement mixed soil which is soil mixed with cement to investigate and estimate the difficulty degree of work and the proper water content. So I would like to present the fundamental data that establish the work standard of the cement mixed soil. In conclusion, in this study the slump value of the cement mixed soil increases over-all according to the increase of the water content although it has a little difference of the increase range and it is smaller than one of the soil. It is estimated that the aggregating and throwing work of the cement mixed soil which is mixed with 6% and 9% cement would be fine when it has the 25%~27% water content and the wall plastering work is the 30%~32% and the floor plastering work is the 30%~35% and the flowing and pouring work is the 40%~42% water content as well as the mold compacting work is the 20%.

조일호 Cho Il Ho , 성찬용 Sung Chan Yong

DOI: JKWST Vol.48(No.4) 23-30, 2006

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This study is performed to evaluate flowability of high flowable concrete using ordinary portland cement, crushed coarse aggregate, crushed sand, sea sand, fly ash, lime powder and superplasticizer. The slump flow and air content are increased with increasing the content of lime powder. But, the O-type funneling time and Box-type passing are decreased with increasing the content of lime powder. The slump flow, air content, O-type funneling time, Box-type passing and L-type filling of target compressive strength 21-27 MPa and 35-42 MPa at curing age 28 days are 47-50 cm and 56-60 cm, 4.2-5.5% and 4.0-5.7%, 8-12s and 5-10s, 4.3-5.0 cm and 3.4-5.0 cm, and excellent, respectively. These concrete can be used for high flowable concrete.

김용성 Kim Yong-seong

DOI: JKWST Vol.48(No.4) 33-40, 2006

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In present study, the principal stress condition needed to conduct cubical large-scale triaxial test which can reflect three dimensional stress condition (or plain strain condition) in a dam was investigated by performing model test and numerical analysis and the principal stress ratio varying with the height of CFRD was examined. Also, the principal stress ratio in CFRD body was investigated from the monitoring results of horizontal and vertical earth pressure gages, installed in the center zone and lower part of transition zone of the dam body, respectively, in order to consider the principal stress condition in the large-scale triaxial test to model the behavior of CFRD. The result of the study indicated that the principal stress ratio decreased gradually from the lower to the upper part in the dam body for its center axis and was about 0.5 and 0.2 in the lower and upper part, respectively.

박재성 Park Jae Seong , 장병욱 Chang Pyoung Wuck , 손영환 Son Young Hwan , 김성필 Kim Seong Pil

DOI: JKWST Vol.48(No.4) 41-49, 2006

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Since particle size distribution curves are useful to estimate permeability of soil, many formulae for permeability coefficient (k) have been published using the parameter from the curves and factors, such as grain size, particle shape and void ratio of soils. However, the parameters such as C_c, C_u and D_n, derived from only some discrete points on the curve are insufficient to represent the whole gradation. In this paper fractal dimension which is quite new concept and known to be able to represent the entire curve of particle size distribution is employed for the parameters. An empirical formula of permeability coefficient has been developed with fractal dimension and percent of finer than 0.075 mm. The formula developed from this study has confirmed its effectiveness by a series of laboratory tests and comparison to other published formulae. It is found that permeability coefficient is proportional to fractal dimension and inversely proportional to percent of fines.

이달원 Lee Dal Won

DOI: JKWST Vol.48(No.4) 51-57, 2006

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This study was carried out to investigate the soil water characteristic curve and prediction of void ratio with net stress and matric suction using the linear elastic and volumetric deformation analysis method on unsaturated silty. The unsaturated soil tests were conducted using a modified oedometer cell and specimens were prepared at water content 2 times of liquid limit and required void ratio. The axis translation technique was used to create the desired matric suctions in the samples. It is shown that soil water characteristic curve and volumetric water content were affected significantly by preconsolidation pressure. As a matric suction increases, the reduction ratio of void ratio was shown to considerably small. Also, the predicted and measured void ratio for unsaturated soils using the linear elastic and volumetric deformation analysis showed good agreement as net stress and matric suction increases.

김용성 Kim Yong-seong

DOI: JKWST Vol.48(No.4) 59-66, 2006

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In this study, construction modulus, void ratio and settlement characteristics of 38 CFRD in domestic and foreign countries were investigated from monitoring data. The effect of field dry density and void ratio to dam body was analyzed. The standard void ratio of CFRD that can be easily used by dam designers and field engineers was proposed from the monitoring data. It was confirmed that we can get the degree of compaction needed for reasonable compaction of dam body by calculating the field dry density from inverse operation of the standard void ratio. It was thought that the void ratio of CFRD depends on shape coefficient and in case of a high shape coefficient, the void ratio was high with its void ratio 0.17 -0.38.

이달원 Lee Dal Won

DOI: JKWST Vol.48(No.4) 67-74, 2006

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This study was carried out to investigate the liquefaction behaviour of saturated silty sand under monotonic loading conditions. The undrained soil tests were conducted using a modified triaxial cell and specimens were prepared using the moisture tamping method. Undrained triaxial compression tests were performed at different confining pressures, void ratios and overconsolidation ratios and the samples were sheared to axial strains of about 20% to obtain monotonic loading conditions. It is shown that increasing confining pressures, void ratios and overconsoildation ratios increases the deviator stress, but it has no effect on increasing the dilatant tendencies. It is shown that complete static liquefaction was observed regardless of increases in the confining pressure, void ratio and overconsolidation ratio. Therefore, the confining pressure, void ratio and overconsoildation ratio does not provide significant effects on the liquefaction resistance of the silty sand. The presence of fines in the soil was shown to greatly increase the potential for static liquefaction and creates a particle structure with high compressibility for all cases.

손재권 Son Jae Gwon , 최진규 Choi Jin Kyu , 구자웅 Koo Ja Woong , 송재도 Song Jae Do , 조재영 Cho Jae Young , 김영주 Kim Young Ju

DOI: JKWST Vol.48(No.4) 77-86, 2006

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This study was performed to investigate the stream water quality characteristics in the Dowoncheon basin of Dongjin River during the 12 months from January to December in 2005. Also, pollutant loads were calculated on the basis of the water quality and runoff results. The measured pH and EC of the stream water were ranged 6.48-7.32, 18.06~38.60μS/㎝, respectively. The concentration of DO, BOD, COD, SS, T-N and T-P were observed as 4.90-11.50 mg/L, 0.5-6.0 mg/L, 1.22-18.46 mg/L, 1.0-2,124.0 mg/L, 1.35-5.67 mg/L, 0.02-0.43 mg/L respectively. T-N showed low correlativity with other water quality parameters. However, T-P had very high correlativity with COD and SS. In the meantime, the runoff pollutant loads of T-N, T-P were estimated as 72,114 kg/yr, 5,027 kg/yr. In the case of the correlativity between runoff pollutant loads and concentrations, T-N did not show significant relationships, while T-P had significant relationships.