• Water for future
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• v.7 no.2
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• pp.107-111
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• 1974

Annual runoff in the Nakdong river basin has been analyzed to find the probability functions of best fit to distribution of historical annual runoff. The results obtained are as follows; (1) Log-normal 3-parameter disrtibution is believed as the probability function of best fit to historical distribution (2) Log-normal 3-parameter disrtibution is believed as the best fit probability function among Log-normal dist-ributions. (3) In the test of goodness of fit, $x^2-test$ shows that probability of $x^2-valus$ in Log-normal 3-parameter distribution is nearly more than 90%. But in the Simirnov-Kolmogorov test, hypotheses for the probability distributions cannot be rejected at significance level 5% & 1%. (4) Among 7 gauging stations, Dongchon & Koryung-Bridge's records show lower fitness to the theoretical probability functions than other 5 gauging station's

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1387-1391
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• 2007

In this study, water quality prediction that is necessary to water quality forecasting system is performed using 2-D river analysis models RMA-2 and RAM4. RAM4 is suitable to water quality forecasting system cause it is possible to put in the pollutants as a mass type boundary condition. Instant injections of pollutants at Yongdamdaegyo Bridge in Namhangang River are simulated and the behavior of pollutant cloud is observed. The effects of water quality accident to Paldang 2 water intake plants in Paldangho Lake is analyzed with time variation. And extra flow simulation is performed for mitigation of pollution. Several cases of water quality forecasting system at home and abroad are investigated and the direction of water quality forecasting system is presented.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.5
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• pp.109-118
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• 2018

Noryang Temporary Palace was a place where king Jeongjo (1752-1800) would have lunch after crossing the Temporary Palace River on his way to Hwaseong Temporary Palace to worship at Hyeonryungwon, the tomb of his father, Sadoseja. The government offices in charge of ship bridge construction 'Jugyosa' and 'Byeoljangso' were located in the Temporary Palace. The central buildings of the Haenggung Palace, which ranged up to Yongyangbongjeojeong, were arranged to observe both 'Jugyosa' and 'Byeoljangso' from the Temporary Palace by lifting the ground from Sammun Gate to Yongyangbongjeojeong. Yongyangbongjeojeong, the center of Noryang Temporary Palace, features the style of royal palace architecture and functions of housing architecture. The 'Jugyosa' and 'Byeoljangso' buildings had eight quarters. According to the records, in addition, 15 wood sheds, 5 rice hubs, 3 barns, 1 side gate quarter, 1 front gate, 70 separate sheds, 2 suragan temporary buildings, oesammun gate and hongsalmun gate were found. Such architectural layout is matched with the Temporary Palace Jugyohwaneodo Painting.

• Structural Engineering and Mechanics
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• v.29 no.2
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• pp.155-169
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• 2008

A MOM-based algorithm (MOMA) has been developed for moving force identification from dynamic responses of bridge in the companion paper. This paper further evaluates and investigates the properties of the developed MOMA by experiment in laboratory. A simply supported bridge model and a few vehicle models were designed and constructed in laboratory. A series of experiments have then been conducted for moving force identification. The bending moment and acceleration responses at several measurement stations of the bridge model are simultaneously measured when the model vehicle moves across the bridge deck at different speeds. In order to compare with the existing time domain method (TDM), the best method for moving force identification to date, a carefully comparative study scheme was planned and conducted, which includes considering the effect of a few main parameters, such as basis function terms, mode number involved in the identification calculation, measurement stations, executive CPU time, Nyquist fraction of digital filter, and two different solutions to the ill-posed system equation of moving force identification. It was observed that the MOMA has many good properties same as the TDM, but its CPU execution time is just less than one tenth of the TDM, which indicates an achievement in which the MOMA can be used directly for real-time analysis of moving force identification in field.

• Smart Structures and Systems
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• v.19 no.1
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• pp.39-46
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• 2017

Finite element model updating is very effective procedure to determine the uncertainty parameters in structural model and minimize the differences between experimentally and numerically identified dynamic characteristics. This procedure can be practiced with manual and automatic model updating procedures. The manual model updating involves manual changes of geometry and analyses parameters by trial and error, guided by engineering judgement. Besides, the automated updating is performed by constructing a series of loops based on optimization procedures. This paper addresses the ambient vibration based finite element model updating of long span reinforced concrete highway bridges using manual model updating procedure. Birecik Highway Bridge located on the $81^{st}km$ of Şanliurfa-Gaziantep state highway over Firat River in Turkey is selected as a case study. The structural carrier system of the bridge consists of two main parts: Arch and Beam Compartments. In this part of the paper, the arch compartment is investigated. Three dimensional finite element model of the arch compartment of the bridge is constructed using SAP2000 software to determine the dynamic characteristics, numerically. Operational Modal Analysis method is used to extract dynamic characteristics using Enhanced Frequency Domain Decomposition method. Numerically and experimentally identified dynamic characteristics are compared with each other and finite element model of the arch compartment of the bridge is updated manually by changing some uncertain parameters such as section properties, damages, boundary conditions and material properties to reduce the difference between the results. It is demonstrated that the ambient vibration measurements are enough to identify the most significant modes of long span highway bridges. Maximum differences between the natural frequencies are reduced averagely from %49.1 to %0.6 by model updating. Also, a good harmony is found between mode shapes after finite element model updating.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.1 s.16
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• pp.63-68
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• 2005

LSIV (Large Scale Image Velocimetry), a technique of image analysis on velocity measurement, was applied to a hydraulic model experiment of river confluence. The surface velocities measured by using LSIV showed similar results with the mean velocities by using a traditional velocimeter, While a general velocimeter can measure only local point velocity, LSIV can measure whole velocity field with one shot. When it is applied to river confluence or around a bridge pier where local flow is dominant, LSIV may be a powerful tool to measure velocity field.

• Journal of Korea Water Resources Association
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• v.30 no.4
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• pp.401-409
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• 1997

This study aims to predict the bed elevation change of river and reservoir by compound water model, two-dimensional jet model and one-dimensional density current model, assuming that the river has a single channel and the reservoir has multiple channels. In numerical model, discharge and water level changes is obtained by flow continuity equation and flow momentum equation through double-sweep method, and then applied to sediment continuity equation to predict the scour and deposit of channel bed. The span ranged from the Bosung Dam to Mundueok Bridge at the upstream of Juam Dam, which is approximately 31km long (13km of river and 18km of reservoir), is taken as survey area.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.139-139
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• 2021

Flooding events often result from extreme precipitations driven by various climate mechanisms, which are often disregarded in flood risk assessments. To bridge this gap, we propose a climate-mechanism-based flood frequency analysis that accommodates the direct linkage between the dominant climate processes and risk management decisions. Several statistical methods have been utilized in this approach including the Markov Chain analysis, K-nearest neighbor (KNN) resampling approach, and Z-score-based jittering method. After that, the impacts of climate change are associated with the modification of the transition matrix (TM) and the application of the quantile mapping approach. For this study, we have selected the Nam River Basin, South Korea, to consider the heterogeneous impacts of the two climate mechanisms, including the Tropical Cyclone (TC) and non-TCs. Based on our results, while both climate mechanisms have significant impacts on future flood extremes, TCs have been observed to bring more significant and immediate impacts on the flood extremes. The results in this study have proven that the proposed approach can lead to a new insights into future flooding management.

• The Journal of the Korea Contents Association
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• v.17 no.2
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• pp.535-542
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• 2017

There is a big difference of discharge rate between drought and flood period in Korea since the importance of water resources management has come to the fore. To know a river characteristics, it needs to estimate river discharge accurately. River discharge is calculated using the measured velocity of cross section and the estimated area of watercourse as input parameters into continuity equation. Generally, flow rate over a river is estimated from the relation equation between level and discharge, in this case, there are weakness for only the equal depths and the equal discharge estimated. In the present study, therefore, water surface slope was estimated using measured water level of Seongseo water level observation station and measured water level using ADVM at Gangchang Bridge. And then, we developed the discharge calculation equation using water surface slope. A method to easily calculated flow rate from the measured depth of the two points that are suggested by reflecting water surface slope because natural stream is unsteady flow, not uniform flow or not steady flow.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.4
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• pp.542-554
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• 2015

Grain size, the content of ignition loss (IL), and the concentrations of chemical oxygen demand (COD), acid volatile sulfide (AVS), and trace metals (Fe, Mn, Cu, Pb, Zn, Cd, Cr, As, and Hg) in surface sediments from the Taehwa River estuary, Ulsan, were measured to evaluate pollution levels and potential ecological risks of organic matter and trace metals in estuarine sediment. The mean grain size (Mz) of sediments in the study region ranged from $-0.8-7.7{\varphi}$ (mean $2.8{\pm}2.4{\varphi}$). Surface sediments in the upstream region of the Taehwa River were mainly composed of coarse sediments compared to the downstream region. The concentrations of IL, COD, AVS and trace metals in the sediment were much higher at downstream sites of Myeongchon Bridge in the vicinity of industrial complexes than at upstream sites of those in the vicinity of the residential areas due to the anthropogenic input of organic matter and trace metals by industrial activities. On the basis of several geochemical assessment techniques [sediment quality guidelines (SQGs), enrichment factor (EF), geoaccumulation index ($I_{geo}$), pollution load index (PLI) and ecological risk index (ERI)], the surfaces sediments in the study region are not highly polluted for trace metals, except for As. However, the higher concentrations in downstream study regions of the Taehwa River could impact benthic organisms including shellfish (i.e. Manila clam) in sediments.