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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of The Korean Society of Civil Engineers
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Korean Society of Civil Engeneers
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Volume & Issues
Volume 29, Issue 6D - Nov 2009
Volume 29, Issue 6C - Nov 2009
Volume 29, Issue 6B - Nov 2009
Volume 29, Issue 6A - Nov 2009
Volume 29, Issue 5D - Sep 2009
Volume 29, Issue 5C - Sep 2009
Volume 29, Issue 5B - Sep 2009
Volume 29, Issue 5A - Sep 2009
Volume 29, Issue 4D - Jul 2009
Volume 29, Issue 4B - Jul 2009
Volume 29, Issue 4A - Jul 2009
Volume 29, Issue 4C - May 2009
Volume 29, Issue 3D - May 2009
Volume 29, Issue 3C - May 2009
Volume 29, Issue 3B - May 2009
Volume 29, Issue 3A - May 2009
Volume 29, Issue 2D - Mar 2009
Volume 29, Issue 2C - Mar 2009
Volume 29, Issue 2B - Mar 2009
Volume 29, Issue 2A - Mar 2009
Volume 29, Issue 1D - Jan 2009
Volume 29, Issue 1C - Jan 2009
Volume 29, Issue 1B - Jan 2009
Volume 29, Issue 1A - Jan 2009
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Analysis on Looped Stage-Discharge Relation and Its Simulation using the Numerical Model
Kim, Ji Sung ; Kim, Won ; Kim, Dong Gu ; Kim, Chi Young ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1B, 2009, Pages 1~9
This study is focused on the analysis of loop characteristics of stage-discharge relation which is widely used for the production of discharge data and the simulation of loop stage-discharge relation using the numerical model. Analysis of consecutive stage and discharge data at 3 points revealed that loop of stage-discharge relationship is very strong. This means that the existing single stage-discharge relation may include large amount of error. Various flood events are simulated in mainstream of Han river with one-dimensional numerical model. The calculated stage data are compared with measured data. Especially continuous field-flow measurements concurrently collected with an Acoustic Doppler Velocity Meter (ADVM) on Hangang bridge in the case of 2007 flood event are used to verify the model applicability of estimating flows in open channels. This comparison shows that numerical model is an accurate and reliable alternative for making the real stage-discharge relation. Simulation of stage-discharge relation by a numerical model at Paldang and Hangang bridge showed good agreements with measured one, so it may be possible to generate real loop stage-discharge relation with properly calibrated and verified numerical model. It can be concluded that results of this study can contribute to error analysis of conventional single stage-discharge relation and development of loop stage-discharge relation with numerical model.
Impact Assessment of Agricultural Reservoir on Streamflow Simulation Using Semi-distributed Hydrologic Model
Kim, Bo Kyung ; Kim, Byung Sik ; Kwon, Hyun Han ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1B, 2009, Pages 11~22
Long-term rainfall-runoff modeling is a key element in the Earth's hydrological cycle, and associated with many different aspects such as dam design, drought management, river management flow, reservoir management for water supply, water right permission or coordinate, water quality prediction. In this regard, hydrologists have used the hydrologic models for design criteria, water resources assessment, planning and management as a main tool. Most of rainfall-runoff studies, however, were not carefully performed in terms of considering reservoir effects. In particular, the downstream where is severely affected by reservoir was poorly dealt in modeling rainfall-runoff process. Moreover, the effects can considerably affect overall the rainfallrunoff process. An objective of this study, thus, is to evaluate the impact of reservoir operation on rainfall-runoff process. The proposed approach is applied to Anseong watershed, where is in a mixed rural/urban setting of the area and in Korea, and has been experienced by flood damage due to heavy rainfall. It has been greatly paid attention to the agricultural reservoirs in terms of flood protection in Korea. To further investigate the reservoir effects, a comprehensive assessment for the results are discussed. Results of simulations that included reservoir in the model showed the effect of storage appeared in spring and autumn when rainfall was not concentrated. In periods of heavy rainfall, however, downstream runoff increased in simulations that do not consider reservoir factor. Flow duration curve showed that changes in streamflow depending upon the presence or absence of reservoir factor were particularly noticeable in ninety-five day flow and low flow.
Analysis of Impact Climate Change on Extreme Rainfall Using B2 Climate Change Scenario and Extreme Indices
Kim, Bo Kyung ; Kim, Byung Sik ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1B, 2009, Pages 23~33
Climate change, abnormal weather, and unprecedented extreme weather events have appeared globally. Interest in their size, frequency, and changes in spatial distribution has been heightened. However, the events do not display regional or regular patterns or cycles. Therefore, it is difficult to carry out quantified evaluation of their frequency and tendency. For more objective evaluation of extreme weather events, this study proposed a rainfall extreme weather index (STARDEX, 2005). To compare the present and future spatio-temporal distribution of extreme weather events, each index was calculated from the past data collected from 66 observation points nationwide operated by Korea Meteorological Administration (KMA). Tendencies up to now have been analyzed. Then, using SRES B2 scenario and 2045s (2031-2050) data from YONU CGCM simulation were used to compute differences among each of future extreme weather event indices and their tendencies were spatially expressed.The results shows increased rainfall tendency in the East-West inland direction during the summer. In autumn, rainfall tendency increased in some parts of Gangwon-do and the south coast. In the meanwhile, the analysis of the duration of prolonged dry period, which can be contrasted with the occurrence of rainfall or its concentration, showed that the dryness tendency was more pronounced in autumn rather than summer. Geographically, the tendency was more remarkable in Jeju-do and areas near coastal areas.
Effects of Velocity Structures on Tracer Mixing in a Meandering Channel
Seo, Il Won ; Park, Sung Won ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1B, 2009, Pages 35~45
In this study, a laboratory experiment has been performed on a S-curved channel with two curved sections. In the experiments, effects of 3-D velocity structures on mixing characteristics of tracer material were investigated. As a result, it was clearly noticed that the primary flow travels taking the shortest course of the meandering channel and has a very ununiform distribution at the bends. The secondary cell which was developing at the first bend disappears at the crossover, and then, at the next bend, secondary cell is re-developing in the opposite direction. The experimental results show that mixing of tracer is significantly affected by the combined action of ununiform primary flow and secondary cell. The ununiform primary flow separates the tracer cloud in the longitudinal direction, and the secondary cell further separates the retarding tracer cloud mainly in the transverse direction. As a result, these complex flow structures cause separation and spreading of tracer cloud both in the longitudinal and in the transverse directions. The measured dimensionless transverse dispersion coefficients calculated using 2-D routing procedure ranges 0.012-0.875, and is generally proportional to width to depth ratio (W/h). The predicted values calculated by the theoretical equation overestimate slightly the measured transverse dispersion coefficients.
Evaluation of Equations for Estimating Pan Evaporation Considering Regional Characteristics
Rim, Chang-Soo ; Yoon, Sei Eui ; Song, Ju Il ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1B, 2009, Pages 47~62
The climate change caused by global warming may affect on the hydro-meteorologic factor such as evaporation (IPCC, 2001). Furthermore, it is also necessary that the effect of climate change according to geographical condition on evaporation should be studied. In this study, considering geographical and topographical conditions, the 6 evaporation equations that have been applied to simulate annual and monthly pan evaporation were compared. 56 climatologic stations were selected and classified, basing on the geographical and topographical characteristics (urbanization, topographical slope, proximity to coast, and area of water body). The evaporation equations currently being used are applied. These evaporation equations are Penman, Kohler-Nordenson-Fox (KNF), DeBruin-Keijman, Priestley-Taylor, Hargreaves, and Rohwer. Furthermore, Penman equation was modified by calibrating the parameters of wind function and was verified using relative error. The study results indicate that the KNF equation compared best with the pan: relative error was 8.72%. Penman equation provided the next-best values for evaporation relative to the pan: relative error was 8.75%. The mass-transfer method (Rohwer) provided the worst comparison showing relative error of 33.47%. In case that there is a close correlation between wind function and wind speed, modified Penman equation provided a better estimate of pan evaporation.
An Experimental Study to develope the Subsidence Equation for Riprap Protection around the Pier
Ji, Un ; Yeo, Woon Kwang ; Lee, Won Min ; Kang, Joon Gu ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1B, 2009, Pages 63~71
Riprap filter should be installed around the pier to prevent riprap subsidence due to sediment winnowing or leaching between the riprap and bed layers. However, riprap protection without filters is commonly applied in the field because of ambiguous specifications and technical and economical difficulties to install the filter layer. Therefore, the hydraulic experiments were conducted in this study to measure and analyze the riprap subsidence quantitatively with different conditions for thickness of riprap layer, approached velocity, sizes of riprap and bed material. As the velocity was increased and size of bed material and thickness of riprap layer were decreased, the subsidence was increased. Consequently, the dimensionless riprap subsidence equation was derived using the synthesized experimental results. The results of this study could be employed as a standard criterion or predictor to evaluate the subsidence stability.
Impact of Secondary Currents on Solute Transport in Open-Channel Flows over Smooth-Rough Bed Strips
Kang, Hyeongsik ; Choi, Sung-Uk ; Kim, Kyu-Ho ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1B, 2009, Pages 73~81
This paper presents a numerical investigation of the impact of the secondary currents on solute transport in open-channel flows. The RANS model with Reynolds stress model is used for flow modeling, and the GGDH(generalized gradient diffusion hypothesis) model is used to close the scalar transport equation. Using the developed model, the impact of secondary currents on solute transport in open channel flows over smooth-rough strip is investigated. Through numerical experiments, the secondary currents are found to affect the solute spreading, leading a movement of the position of the peak concentration and a skewed distribution of solute concentration. Due to the lateral flow of secondary currents near the free surface, the concentration at the rough strip is found to be larger than that at the smooth strip bed. The solute at the rough strip is more rapidly transported than smooth bed. A magnitude analysis of the solute transport rate in scalar transport equation is also carried out to investigate the effect of secondary currents and scalar flux on the concentration distribution.
The Experimental Study of Distribution Characteristics of Lift-force Acting under Pier Deck
Park, Sang Kil ; Park, Hyun Soo ; Ahn, Ik Seong ; Kim, Woo Saeng ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1B, 2009, Pages 83~90
This study describes the characteristics of distribution of lift-force acting under pier deck through physical experiment. The shape of peak wave pressure was sharp when compressed air existed but was not sharp without that. Values of lift-force was different between edge point and center point in the same block. Distribution of lift-force was expressed differently owing to dimensionless of deck length (l/L), wave steepness (H/L), clearance height per wave height (D/H). The dimensionless factor of D/H affected on the lift-force the clearance between still water surface and decks. This decided the maximum of lift-force. In the case of the same values of D/H, the lift-force are changed by the wave steepness (H/L). Because (D/H) become smaller as the wave steepness (H/L) is increased the height of decks must be decided with the condition which don't have the clearance with
for the stable design of deck of pier. Effect of reducing lift force was greater in the on-shore than the off-shore according to compressed air existence. This researches points out that design of deck should retain compressed air in order to reduce wave lift force.
Adsorption of Arsenate on the Synthesized Layered Double Hydroxide Materials
Choi, Young-Mu ; Choi, Won-Ho ; Kim, Jung-Hwan ; Park, Joo-Yang ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1B, 2009, Pages 91~96
Layered double hydroxide is synthesized and used in the arsenate adsorption experiments. The shapes of two materials analyzed by TEM showed that unheated material is amorphous in shape, micro-sized while heat treated material showed more crystallized in shape and nano-sized. X-ray diffraction showed this result more obvious.
adsorption-desorption results showed that the materials are mesoporous and the specific surface area of the heated material is more than two times larger than the unheated material. Adsorption of As(V) is expected to be more in the heated material than the unheated material. Kinetic test of arsenate adsorption showed very fast reaction. The reactivity of Fe with As(V) might be the main factor for this result. The reaction kinetic of the heated and the unheated materials were similar and even the adsorption isotherms showed similar results for both materials. Both materials are found to be useful in remediation of soil and groundwater polluted by waste mine tailings consist of high concentration of As(V).
Removal of NAPL TCE using Cement/Slag contained Fe(II)
Lee, Seung-Hyoung ; Park, Jung-Hyun ; Choi, Won-Ho ; Park, Joo-Yang ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1B, 2009, Pages 97~103
The decompostion characteristics of NAPL TCE in cement/slag/Fe(II) system were studied with various TCE concentration and amounts of binders (cement/slag) For analyses of the TCE degradation by cement/slag/Fe(II), TCE solution injected using gas-tight syringe after TCE solution dissolved a methanol. Initial concentrations of TCE are 0.42 mM, NAPL condition 11.7 mM and saturated condition 16.8 mM respectively. The result showed that the cases of 8.4 mM and 4.2 mM are decreased 88% of total TCE concentration within 18 days. NAPL condition 11.7 mM was decreased 84% within 50 days and saturated condition 16.8 mM was decreased 60% of total TCE concentration within 60 days respectively. This showed that degradations of TCE in various concentrations were in one kind reaction as pseudo-first-order. TCE was dissolved as aqueous solution before degraded. The reaction rate was increased
when the mass of media 0.1, 0.2, 0.3 S/L rate was increased. TCE reaction speed is affected by cement/slag surface ares in this system. When HDTMA, experimental facter, was added, TCE decomposition rate was high despite the high concentration of NAPL. and The decompostion characteristics of NAPL TCE in cement/slag/Fe(II) system were studied by using modeling.
Impacts of Nitrate in Base Flow Discharge on Surface Water Quality
Kim, Geonha ; Lee, Hosik ;
Journal of The Korean Society of Civil Engineers, volume 29, issue 1B, 2009, Pages 105~109
It is a well known fact that baseflow discharge of rainfall runoff impacts on water quality of surface water significantly. In this paper, impacts of nitrate discharged as base flow on stream water quality were studied by using a software, PULSE from USGS to calculate monthly ground water discharge from hydrograph. We used water quality and flow rate data for Ghapcehon2 site in Daejeon city for year 2005 as well as ground water quality data in the watershed acquired from government agencies. Agricultural and forestry land use are dominant for upstream of Ghapcheon2 in the watershed. Base flow contributes about 85~95% of stream flows during spring and fall while 25~38% of stream flow was induced by base flow during summer and winter. Monthly nitrate loading discharged as base flow for Ghapcheon2 was estimated by using averaged nitrate concentration of groundwater in the watershed. Nitrate loading induced by base flow at Ghapcheon2 was estimated as 5.4 ton of
, which is about 60% of nitrate loading of surface water, 9.2 ton of
. Seasonal variation of nitrate concentration of base flow was estimated by dividing monthly nitrate loading by monthly base flow discharge. Nitrate concentration of groundwater was increasing from rainy season. From this study, it can be understood that ground water quality monitoring is important for the proper manage of surface water quality.