김성준 Kim Seong Joon , 권형중 Kwon Hyung Joong , 신사철 Shin Sha Chul

DOI: JKWST Vol.47(No.1) 3-9, 2005

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The purpose of this study was to analyze the climatic water balance of the Korean peninsula using meteorological data and the evapotranspiration (ET) derived from NOAA/AVHRR, Quantifying water balance components is important to understand the basic hydrology. In this study, a simple method to estimate actual ET was proposed based on a regression approach between NDVI and Morton's actual ET using NOAA/AVHRR data, The Mortons actual ET for land surface conditions was evaluated using a daily meteorological data from 77 weather stations, and the monthly averaged Morton's ETs for each land cover was compared with the monthly NDVIs during the year 2001. According to the climatic water balance analysis, water deficit and surplus distributed maps were created from spatial rainfall, soil moisture, and actual and potential ETs map. The results clearly showed that the temporal and spatial characteristics of dryness and wetness may be detected and mapped based on the wetness index.

서교 Kyo Suh , 이정재 Jeong-jae Lee , 서병륜 Byong-yoon Suh

DOI: JKWST Vol.47(No.1) 13-22, 2005

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Despite the variety in sizes and shapes of agricultural products, the unified standardization of packing has been a long time necessity. In this study the stacking efficiency of packing standards for each box using packing Monte Carlo simulation based on the standard pallet is evaluated. As a result of simulation the unified packing standard for agricultural products is suggested by 550/366 mm. With this study it is expected that the unification of the standards can help to increase the utilization of reusable packages and to improve efficiency of agricultural logistics.

성찬용 Sung Chan Yong

DOI: JKWST Vol.47(No.1) 25-32, 2005

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This study was performed to evaluate strengths and non-destruction properties of super flow concrete using recycled coarse aggregate. At the curing age of 28 days, the compressive strength was 22.7~37.5 MPa, the splitting tensile strength was 2.65~3.73MPa, the flexural strength was 5.78~6.86MPa, the ultrasonic pulse velocity was 3,103~3,480m/s, the dynamic modulus of elasticity was 3.401×10⁴~4.521×10⁴MPa, respectively. The strengths, ultrasonic pulse velocity and dynamic modulus of elasticity of super flow concrete were decreased with increasing the content of recycled coarse aggregate. The super flow concretes using recycled coarse aggregate were improved by substitution in the range of less than the fly ash content 30% and recycled coarse aggregate content 75%.

장병욱 Chang Pyoung Wuck , 우철웅 Woo Chull Woong , 김성필 Kim Seong Pil

DOI: JKWST Vol.47(No.1) 35-42, 2005

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The research has been done to obtain a empirical equation for the depth of replacement by the analysis of data collected from 8 sea-dike construction sites of south coast of Korean peninsula. The correlation analysis results show that the depth of replacement was mainly dependent upon the height of embankment and the undrained shear strength of soft soil. The suggested regression equation was quite well predicted the depth of replacement and recommended to use under certain restrictions where the embankment height was less than 10m and under 0.2 kgf/㎠ of the undrained shear strength of soil.

권무남 Kwon Moo Nam , 김현기 Kim Hyun Ki

DOI: JKWST Vol.47(No.1) 43-50, 2005

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This test was performed to evaluate the change of the unconfined compressive strength, strength parame-ters which resulted from direct shear test and oil residue percents analyzed by GC-MS as time lapse, oil addition. Unconfined compression strength of 10% kerosene added by weight of dry soil recovered as time passed. In the case of 5% kerosene added, the strength recovered as much as clean clayey soil after about 50 days passing. For the case of diesel added, the recovery of unconfined compressive strength was not shown even though about 60 days passed. The strength parameters (c, ψ) of kerosene added not changed but for diesel added, the cohesion was very decreased as diesel addition increased. Residual percent of kerosene in the soil was less than that of diesel as time passed.

윤상묵 Yun Sang Muk , 장병욱 Chang Pyoung Wuck , 원정윤 Won Jung Yun , 김성필 Kim Sung Pil

DOI: JKWST Vol.47(No.1) 51-59, 2005

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The settling rate of the dredged soil may vary with mineral composition, grain size distribution, initial con contration and salt concentration of suspension of the site. A series of settling column test was performed to investigate the settling rate characteristics of solid suspension material from dredging and reclamation. The settling rate of soil mixed with various size of particles depended on clay fraction which showed a inherent flux. A model was developed to predict the particle flux of mixed soil from the clay flux and its applicability was verified.

이달원 Lee Dal Won , 정성규 Jeong Seong Gyu

DOI: JKWST Vol.47(No.1) 61-68, 2005

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In this study, it was proposed that an equation for predicting consolidation settlement on soft clay ground, which separate total settlement into primary and secondary consolidation settlement equation. The consolidation settlements by the proposed equation and by the measured settlements from laboratory model test were compared and verified for its application. It was appeared that the proposed equation from the laboratory model test approach to be more realistic comparing to the result of Terzaghi's equation. From the above application, it was concluded that the final settlement prediction by. the Hyperbolic, Asaoka methods is needed to the initial settlement but the proposed equation could be much applicable in the lacking condition of measured data of the initial period.

홍성구 Hong Seonggu

DOI: JKWST Vol.47(No.1) 71-77, 2005

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Recycling of reclaimed concrete (RC) is very important in the management of construction and demolition wastes. Most of RC is utilized for land-filling after crushing in this country. In this study, a series of elution experiments were conducted to investigate the type and amount of pollutants released from the crushed RC. Most water quality parameters including heavy metals and some organic compounds were below standards for drinking water. Some of heavy metals such as As, Cd, Pb, Hg were detected in 0.5 N H₂SO₄ solution after 24-hour immersing RC, which was conducted for evaluating a long term release effect. The con-centration of the heavy metals were higher than the drinking water standards. The results also showed significant adsorption of heavy metals by crushed RC. Potential risks, based on the result of this study were not high in using crushed RC for land-filling. Appropriate management of RC would reduce the risk, for example the separation of hazardous materials from construction wastes. Long term evaluations for the sites of land filled with RC would be required to assess the environmental impacts.

함종화 Jong-hwa Ham , 윤춘경 Chun G. Yoon , 구원석 Won-seok Koo , 김형철 Hyung-chul Kim , 신현범 Hyum-bhum Shin

DOI: JKWST Vol.47(No.1) 79-91, 2005

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Wetland systems are widely accepted natural water purification systems around the world in nonpoint sources pollution control. Constructed wetlands have become a popular technology for treating contaminated surface and wastewater. In this study, the field experiment to reduce nonpoint source pollution loadings from polluted stream waters using wetland system was performed from June 2002 to March 2004, including winter performance using four newly constructed wetlands. The Dangjin stream water flowing into Seokmun estuarine lake was pumped into wetlands, and inflow and hydraulic residence time of the system was 500㎥~1500㎥/day and 2~5 days respectively. After 3 years operation plant-coverage was about 80~90% from zero at initial stage even with no plantation. Average water quality of the influent in growing season was BOD₅ 3.96 mg/L, TSS 22.98 mg/L, T-N 3.29 mg/L, T-P 0.30 mg/L. The average removal rate of four wetlands for BOD₅₅ 4.92 mg/L, TSS 12.47 mg/L, T-N 5.54 mg/L, and T-P 0.32 mg/L, respectively. The average removal rate of four wetlands for them was -21%, 23%, 33%, and 53%, respectively. The reason of higher BOD₅ effluent concentration in winter season might be that low temperature restrained microorganism activity and a organic body from the withered plant and algae was flown out. Except the result of BOD₅, the effectiveness of water quality improvement in winter season was satisfactory for treating polluted stream waters, and BOD₅ variation was within the range of background concentration. Performance of the experimental system was compared with existing data base (NADB), and it was within the range of general system performance. Overall, the wetland system was found to be satisfactory for NPS control such as improvement of polluted stream water.

권순국 Soon-kuk Kwun , 이경도 Kyung-do Lee , 조영현 Young-hyun Cho , 김성배 Song-bae Kim , 전기설 Gi-seol Cheon

DOI: JKWST Vol.47(No.1) 93-102, 2005

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A prototype surface flow constructed wetland was built in the upstream area of Sihwa reclaimed tidal lands to improve the water quality of Lake Sihwa by treating severely polluted stream water. In this study, we monitored hydrology, macrophyte (Phragmites communis Trin.) growth, and water quality in the Banwol and Donghwa wetlands to evaluate their performance during the initial period after the completion of wetland construction. The average removal efficiency(%) in each wetland was relatively low compared with the performance data from the North America Wetland Treatment System Database (NADB), which mainly includes urban sewage-treatment wetlands. However, the average removal rates per unit area (g/㎡/day) were 0.72, 0.72 and 0.51 (BOD), 2,04, 2.46 and 0.70 (SS), 0.89, 0.43 and 1.09 (TN) and 0.02, 0.02 and 0.02 (TP) in the Banwol and Donghwa wetlands and NADB, respectively. The overall performance of the Banwol and Donghwa wetlands was within the expected range of the wetland system processes contributing the reduction of the pollutant load to Lake Sihwa during the initial period of wetland operation. Considering the low influent concentration, high hydraulic loading rate, and insufficient macrophyte growth since the wetland was constructed, better performance is expected if an improved operational scheme is adopted.